U.S. patent number 3,661,452 [Application Number 04/731,934] was granted by the patent office on 1972-05-09 for xerographic reproduction machine.
This patent grant is currently assigned to Xerox Corporation. Invention is credited to Ellsworth D. Hewes, Norbett H. Kaupp.
United States Patent |
3,661,452 |
Hewes , et al. |
May 9, 1972 |
XEROGRAPHIC REPRODUCTION MACHINE
Abstract
A reproduction machine having a photoreceptor imaging medium in
belt configuration which is exposed by a flash illumination system
in timed relation to the feeding of sheets of copy paper prior to
image transfer. The belt is arranged to be maintained flat during
exposure and development with image transfer being effected along a
curved presentation of the belt between the two flat sections of
the belt.
Inventors: |
Hewes; Ellsworth D. (Rochester,
NY), Kaupp; Norbett H. (Newark, NY) |
Assignee: |
Xerox Corporation (Rochester,
NY)
|
Family
ID: |
24941504 |
Appl.
No.: |
04/731,934 |
Filed: |
May 24, 1968 |
Current U.S.
Class: |
399/195; 399/217;
355/67 |
Current CPC
Class: |
G03G
15/263 (20130101) |
Current International
Class: |
G03G
15/26 (20060101); G03G 15/00 (20060101); G03b
027/10 () |
Field of
Search: |
;355/3,5,11,16,67 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Horan; John M.
Claims
What is claimed is:
1. In an electrostatic machine for reproducing copies of originals
onto sheets of copy paper having a photoconductive plate in the
form of a flexible belt, means for producing a uniform charge
thereon, means for supporting and moving the belt at a
predetermined rate and in a path having at least one section
wherein the belt travels in a flat condition to define the exposure
station therefor, an illumination device for illuminating an
original in full frame when the device is in its operative
condition and projecting the illuminated full frame area onto the
belt at the exposure station to produce an electrostatic latent
image of an original thereon, energizing means for activating the
illumination device to its operative condition for a short period
of time to effect flash exposure of the original in full frame
while the belt moves, the time of each flash exposure being
sufficiently short so as not to cause a blurred latent image, means
for developing the latent image with toner particles, a paper
supply, paper feed means for feeding individually sheets of paper
from the paper supply and into contact with the belt at the
transfer station therefor preparatory to the transfer of developed
images thereon, the improvement including control means operatively
connected to the energizing means and the paper feed means for
actuating the latter in a predetermined timed relationship to
activation of said illumination device by the energizing means for
effecting the feed of sheets of paper in timed relation to the
production of corresponding latent images on the belt.
2. The machine of claim 1 including a registration mechanism
interposed between the paper supply and the transfer station and
including a member movable into the paper feed path to momentarily
arrest and register the leading edge of a sheet of paper prior to
the movement thereof to the transfer station, said control means
being associated with the registration mechanism for actuating the
member to release a sheet for movement in timed relation to
activation of said illumination device.
3. In an electrostatic machine for reproducing copies of originals
onto copy paper having a photoconductive plate in the form of an
endless flexible belt, means for producing a charge thereon, means
for supporting and moving the belt at a predetermined rate and in a
continuous path having at least one section wherein the belt
travels in a flat condition and which defines the exposure station
for the machine, an illumination device for illuminating an
original in full frame when the device is in its operative
condition and projecting the illuminated full frame area onto the
belt at the exposure station to produce an electrostatic latent
image of an original thereon, means for developing the latent image
with toner particles, an image transfer station, and paper feed
means for moving individual sheets of paper into contact with the
belt at the transfer station therefor in order to accomplish the
transfer of developed images to sheets of paper, the improvement
including
energizing means for activating the illumination device to its
operative condition for a short period of time to effect flash
exposure of the original in full frame while the belt is in
continuous movement, the time of the flash exposure being
sufficiently short so as not to cause a blurred latent image,
control means operatively connected to said energizing means and
said paper feed means for effecting equally timed successive
activations of the illumination device for producing multiple
exposures of an original and for activating the paper feed means in
the same timed relationship to each activation of the illumination
device.
4. In an electrostatic machine for reproducing copies of originals
onto copy paper having a photoconductive plate in the form of an
endless flexible belt, means for producing a charge thereon, means
for supporting and moving the belt at a predetermined rate and in a
continuous path, an exposure station for the machine, an
illumination device for illuminating an original in full frame when
the device is in its operative condition and projecting the
illuminated full frame area onto the belt at the exposure station
to produce an electrostatic latent image of each original thereon,
means for developing the latent image with toner particles, an
image transfer station, a paper supply, and paper transport means
for moving individual sheets of paper from the paper supply into
contact with the belt at the transfer station therefor in order to
accomplish the transfer of developed images thereon, and toner
fixing means arranged for receiving the sheets after the transfer
of developed images, the improvement wherein
the transport means, the transfer station and the toner fixing
means are arranged in a position so that paper movement occurs in
substantially the same plane thereby effecting the movement of each
sheet in substantially a straight path from the paper supply to the
fixing means.
5. In an electrostatic machine for reproducing copies of originals
onto copy paper having a photoconductive plate in the form of an
endless flexible belt, means for producing a charge thereon, means
for supporting and moving the belt at a predetermined rate and in a
continuous path having at least one section wherein the belt
travels in a flat condition and which defines the exposure station
for the machine, an illumination device for illuminating an
original in full frame when the device is in its operative
condition and projecting the illuminated full frame area onto the
belt at the exposure station to produce an electrostatic latent
image of an original thereon, means for developing the latent image
with toner particles, an image transfer station, and paper feed
means for moving individual sheets of paper into contact with the
belt at the transfer station therefor in order to accomplish the
transfer of developed images to sheets of paper, the improvement
including
energizing means for activating the illumination device to its
operative condition for a short period of time to effect flash
exposure of the original in full frame while the belt is in
continuous movement, the time of the flash exposure being
sufficiently short so as not to cause a blurred latent image,
control means operatively connected to said energizing means for
effecting successive activations of the illumination device for
producing multiple exposures of an original, said control means
being operatively connected to the paper feed means for activating
the paper feed means in timed relationship to activation of the
illumination device while said activation of the illumination
device is being effected.
Description
This invention relates to improvements in reproduction systems such
as copiers or duplicators and, particularly, to improvements in
automatic xerographic systems that is particularly adapted to high
speed operation and is capable of having its sequence timing varied
thereby permitting variable speeds of output.
Since the process of xerography was pioneered by Chester Carlson
and originally disclosed in the Carlson U.S. Pat. No. 2,297,691,
many improvements have been made in xerographic devices and
techniques and new applications therefor. As the result, automatic
machines of various arrangements and speeds for carrying out
xerographic reproduction processes are in wide commercial use. The
present invention constitutes a further improvement in automatic
xerographic processing systems whereby the system may be more
readily employed for relatively high speed production as well as
being adapted to various speeds of production and may be fabricated
into a relatively compact size.
As is well known in recent years, the steadily increasing size of
various industries has required an enormous increase in the amount
of paper work that must be accomplished, maintained, and made
available for wide interplant circulation. In the present day
commercial xerographic machine, which is adapted to produce copies
of between 5 and 60 81/2 .times. 11 inch sheets of copy per minute,
the photoreceptor device is in the form of a drum which rotates in
timed unison relative to a plurality of processing stations. These
devices employ a charging device, a stationary copy projection
device, a developing mechanism, a sheet feeding mechanism, a
transfer charging device, a sheet pick-off device, a paper
transport mechanism and a fuser mechanism. In addition, there is
provided a drum cleaning mechanism in order to remove excess or
residual toner particles from the drum surface prior to the
recharging of the drum preparatory to document exposure.
The limiting feature in these present day machines is the use of
the xerographic drum which seriously limits the positioning and
action of each of the processing devices and, in particular, the
requirement of presenting a flowing image upon the xerographic drum
as a document is being scanned. In commercial machines it has been
proven that the preferred handling of documents during scanning
thereof is provided by a fixed glass platen upon which a document
to be scanned is placed in fixed relation. As the conventional
xerographic drum is rotated, a scanning mechanism scans across the
document and presents light images of the document in the form of a
narrow band of light upon the drum surface as it rotates, thereby
producing a flowing presentation of the light rays upon the drum
surface.
The mechanism which accomplishes the scan of the fixed document
generally involves a slidable carriage for supporting illumination
lamps in addition to drive mechanisms, levers, pulleys, switches,
etc. for accomplishing scanning of the document. As the demands for
faster copying or duplicating has come about, these conventional
machines gnerally have been modified in their respective drive
systems and electrical circuits in order to accomplish a faster
scan for the scanning mechanisms already in the machine. The result
of these modifications is to propel the structures that go to make
up the scanning mechanisms at very great speeds and, as will be
apparent, will place great undue burdens upon the structural
supports of the machine and the scanning mechanism.
Another inherent disadvantage of the drum type printing means for
reproduction machines is the inability to effect a plurality of
images or image areas on the periphery of the drum without
requiring extremely large size drums with their attendant extra
large drive systems and other size requirements for the other
processing components for the machine. With the capability for
utilizing a xerographic surface of relatively large area or length,
it is possible to conduct processing operations simultaneously as
the xerographic surface moves rather than permitting such action to
occur in sequence as is generally the case. Such xerographic
surface may have as many as five document exposures thereon in
various stages of processing thereby permitting simultaneous
processing steps wherein each step may be optimized to a greater
extent than is usually found in practice on machines employing
xerographic drums.
It is therefore the principal object of this invention to improve
xerographic reproduction machines that are capable for general
copying applications and for making high speed copies automatically
and in variable time sequences.
Another object of this invention is to improve xerographic
reproduction machines so that reproductions of a fixed document can
be made quickly and automatically.
Another object of this invention is to improve xerographic machines
of the photoreceptor belt type whereby the operations of the
machine are effected independently of the positioning of the belt
to permit more efficient use of the belt surface.
Another object of this invention is to improve xerographic machines
in a manner such that the various operating cycles are effected in
time relation to the movement of the photoreceptor.
The invention has among its objects a provision of a xerographic
copier-duplicator machine in a compact self-contained form of a
modular design defined by a minimum size and adapted to be
dismantled for replacement of module components, repairs and
cleaning in a minimum of time with minimum effort.
These and other objects of this invention are obtained by means of
the provision of a selenium belt assembly which is adapted to move
a selenium belt through various processing stations two of which
present the belt in flat condition, a stationary-copy projection
apparatus adapted to flash expose a document for exposing a
selenium belt at one of its flat portions, a developer apparatus
adapted to cascade developer material over a portion of the
selenium belt when it is in another flat condition, a sheet feeding
mechanism arranged to quickly present a sheet of paper at a
transfer station which occupies a minimal of area of the belt, a
transfer charging device arranged in conjunction with a paper
transport mechanism for conveying a sheet of paper to a transfer
station and to effect image transfer to the sheet, a sheet pick-off
apparatus and a fuser mechanism arranged to receive individual
sheets of paper for effecting fixing of toner images thereon. The
sheet feeding mechanism, the paper transport, the transfer station
and the fuser mechanism are arranged to provide a paper movement
which generally assumes a straight and shortened path. These
components are modular in design and are operatively positioned
relative to the movable endless selenium belt, the movement of
which is controlled to permit coordinated operation of the
apparatus to reproduce a copy from the stationary document
selectively and automatically.
For a better understanding of the invention as well as other
objects and further features thereof, reference is had to the
following detailed description of the invention to be read in
conjunction with the accompanying drawings, wherein:
FIG. 1 is an exploded right-hand perspective view of the
xerographic reproduction machine with the modular processing
components separated to better illustrate the invention;
FIG. 2 is a schematic sectional view of the xerographic machine
showing the various xerographic processing stations;
FIG. 3 is an isometric view of the illumination and optical system
for the xerographic machine;
FIG. 4 is a sectional view of one side of the lamp assembly
utilized for the illumination device;
FIG. 5 is a sectional view of one end of the lamp assembly;
FIG. 6 is a partial top view of a portion of the lamp assembly and
document platen;
FIG. 7 is a perspective view of the photoconductive belt assembly
utilized in the machine;
FIG. 8 is an elevational view of the belt assembly as seen from the
rear of the machine;
FIG. 9 is an elevational view of the other side of the belt
assembly as seen from the front of the machine;
FIG. 10 is an elevational view of the belt assembly with the belt
mounted thereon partly in section to show various portions of the
interior of the belt assembly;
FIG. 11 is a sectional view taken along line 11--11 in FIG. 10;
FIG. 12 is a partial view of the lower section as seen from the
front of the developer assembly showing the selenium belt in a
relaxed condition;
FIG. 13 is a perspective view of the developer apparatus as seen
from the front of the machine away from association with the
selenium belt utilized in the machine;
FIG. 14 is a front view of the developer mechanism as applied to a
selenium belt;
FIG. 15 illustrates the other side of the developer housing of that
side which faces the rear of the machine;
FIG. 16 is a rear elevational view partly broken away of the
developer housing of that side that is remote from the selenium
belt;
FIG. 17 is a cross-sectional view taken along line 17--17 in FIG.
16 and showing the vertical transport belt;
FIG. 18 is a cross section view of the developer housing taken
along 18--18 in FIG. 16;
FIG. 19 is a cross-sectional view of the upper horizontal
developing material transport device taken along line 19--19 in
FIG. 14;
FIG. 20 is a cross-sectional view of the lower horizontal developer
material transport taken along line 20--20 in FIG. 14;
FIG. 21 is a perspective view of the internal bucket conveyor belt
for the toner materials;
FIG. 22 is a cross section taken along line 22--22 in FIG. 21;
FIG. 23 is an end view of the conveyor belt of FIG. 21;
FIG. 24 is a front view partly in section of the conveyor belt;
FIG. 25 is a plan view partly in section of the toner dispensing
mechanism utilized with the developer assembly of FIG. 13;
FIG. 26 is an enlarged sectional view, partly broken away, of the
toner dispenser, taken along the line 26--26 in FIG. 25;
FIG. 27 is an elevational view, with parts broken away, of the
automatic toner sensor control device used in the developer
housing;
FIG. 28 is a side view of the toner sensor with parts broken
away;
FIG. 29 is a cross-sectional view taken along the line 29--29 in
FIG. 27;
FIG. 30 is a fragmentary view of a detail in the toner sensor;
FIG. 31 is a schematic of the control circuit for the toner sensor
of FIG. 27;
FIG. 32 is an elevational view of the timer mechanism for the toner
sensor;
FIG. 33 is an end view of the timer mechanism shown in FIG. 32;
FIG. 34 is a timing chart indicating the operative sequence of the
timer mechanism;
FIG. 35 is an isometric view of the paper handling and feeding
component;
FIG. 36 is a side elevational view of the paper handling device as
viewed from the rear of the machine;
FIG. 37 is a side elevational view of the paper handling device as
viewed from the front of the machine;
FIG. 38 is a plane view of the paper handling device with parts
broken away;
FIG. 39 is a sectional view taken along line 39--39 in FIG. 38;
FIG. 40 is a sectional view taken along the line 40--40 in FIG.
37;
FIG. 41 is a sectional view of the paper feeding mechanism taken
along line 41--41 in FIG. 37;
FIG. 42 is a sectional view with parts broken away of the paper
registration rollers utilized along with the paper feeding
mechanism;
FIG. 43 is an end view of the double rotary solenoid utilized to
effect sheet registration and feed out;
FIG. 44 is a fragmentary enlarged view of a rotary drive device
taken along the line 44--44 in FIG. 43;
FIG. 45 illustrates another position of operation of the rotary
device of FIG. 44;
FIG. 46 is a sectional view of a detail used with the registration
rollers taken along line 46--46 in FIG. 42;
FIG. 47 is a sectional view of another detail taken along line
47--47 in FIG. 42;
FIG. 48 is a sectional view showing the registration fingers and
taken along line 48--48 in FIG. 42;
FIG. 49 is a sectional view of the roller bearing support taken
along line 49--49 in FIG. 42;
FIG. 50 is a sectional view of a double sheet sensing device used
in conjunction with a paper handling mechanism;
FIG. 51 is a plane view of the device of FIG. 50;
FIG. 52 is an isometric of the horizontal sheet transport system
utilized at a transfer station;
FIG. 53 is a sectional view of the sheet transport system shown in
relation to other components of a reproduction machine;
FIG. 54 is a plane view of the sheet transport system;
FIG. 55 is a perspective view of the fuser assembly utilized in the
machine;
FIG. 56 is an elevational view of the fuser assembly as seen from
the front of the machine;
FIG. 57 is an end view of the fuser assembly as seen from the
output side of the assembly;
FIG. 58 is a sectional view taken along line 57--57 in FIG. 56;
FIG. 59 is a sectional view taken along line 58--58 in FIG. 55;
FIG. 60 is a sectional view taken along line 59--59 in FIG. 55;
FIGS. 61 and 62 are the front view and end view, respectively, of
the drive system for some of the processing components of the
xerographic machine;
FIG. 63 is an elevational view, partly broken away in section of
the brush cleaning assembly used in the xerographic machine;
FIG. 64 is a sectional view of the brush cleaner taken along the
line 64--64 in FIG. 63;
FIG. 65 is a fragmentary view of a detail utilized in the brush
cleaner;
FIG. 66 is a schematic electrical diagram of the fade out lamp
control system view in the xerographic machine;
FIGS. 67 and 68 are schematic electrical diagrams of the
xerographic apparatus and, when combined in end-to-end
relationship, illustrate the complete wiring system; and
FIGS. 69 and 70 are timing charts which when joined illustrate the
timing sequence of operation of some of the processing
components.
Throughout this description, the front of the xerographic
reproduction machine as viewed in FIGS. 1 and 2 is regarded as that
portion which the operator faces while placing a document to be
reproduced in the machine. The right and left end of the machine
are regarded as being to the right and left of the operator as he
faces the machine as he would in viewing FIG. 2.
For a general understanding of the xerographic processing
arrangement in which the invention is incorporated, reference is
had to FIGS. 1 and 2 in which the various system components are
schematically illustrated. As in all xerographic systems based on
the concept disclosed in the above-cited Carlson patent, a light
image of a document to be reproduced is projected onto the
sensitized surface of a xerographic plate to form an electrostatic
latent image thereon. Thereafter, the latent image is developed
with an oppositely charged developing material to form a
xerographic powder image, corresponding to the latent image on the
plate surface. The powder image is then electrostatically
transferred to a support surface to which it may be fused by a
fusing device whereby the powder image is caused permanently to
adhere to the support surface.
In the machine disclosed herein, an original to be copied is placed
upon a transparent support platen P fixedly arranged in an
illumination assembly generally indicated by the reference numeral
10, arranged at the left end of the machine. While upon the platen,
an illumination system, to be described herein, flashes light rays
upon the original thereby producing image rays corresponding to the
informational areas on the original. The image rays are projected
by means of an optical system in the illumination device and for
exposing the photosensitive surface of a xerographic plate in the
form preferably of a flexible photoconductive belt arranged on a
belt assembly generally indicated by the reference numeral 11. Any
flexible photoconductive device may be utilized such as a selenium
belt or the like for purposes of producing an electrostatic latent
image.
The photoconductive belt assembly 11 is slidably mounted upon a
support bracket secured to the frame of the machine and is adapted
to drive a selenium belt 12 in the direction of the arrow as shown
in FIG. 2 at a constant rate. During this movement of the belt, the
reflected light image of an original on the platen is flashed upon
the xerographic surface of the belt at such a speed, measured in
microseconds, that the relative motion of the light rays comprising
the light image and the belt surface is minimal. The belt surface
that intercepts the light rays comprises a layer of photoconductive
material such as selenium on a conductive backing that is
sensitized prior to exposure by means of a charging corona
generator device indicated at 13.
The flash exposure of the belt surface to the light image
discharges the photoconductive layer in the areas struck by light,
whereby there remains on the belt a latent electrostatic image in
image configuration corresponding to the light image projected from
the original on the supporting platen. As the belt surface
continues its movement, the electrostatic image passes through a
developing station B in which there is positioned a developer
assembly generally indicated by the reference numeral 14 and where
the belt is maintained in a flat condition. The developer assembly
14, as will be described in detail hereafter, comprises a vertical
conveying mechanism which carries developing material to the upper
part of the belt assembly 11 whereat the material is dispensed and
directed to cascade down over the upperwardly moving inclined
selenium belt 12 in order to provide development of the
electrostatic image.
As the developing material is cascaded over the xerographic plate,
toner particles in the development material are deposited on the
belt surface to form powder images. As toner powder images are
formed, additional toner particles are supplied to the developing
material in proportion to the amount of toner deposited on the belt
during xerographic processing. For this purpose, a toner dispenser
generally indicated by reference numeral 15 is used to accurately
meter toner to the developer material in the developer assembly
14.
The developed electrostatic image is transported by the belt to a
transfer station C whereat a sheet of copy paper is moved at a
speed approximately in synchronism with the moving belt in order to
accomplish transfer of the developed image. There is provided at
this station a sheet transport mechanism generally indicated at 16
adapted to transport sheets of paper from a paper handling
mechanism generally indicated by the reference numeral 18 to the
developed image on the belt at the station C. The paper handling
mechanism includes a paper support tray for holding a stack of
paper or the like, separating rollers adapted to feed the top sheet
of the stack to feed rollers which direct the sheet material into
contact with transporting devices in the sheet transport mechanism
16.
The transfer of the developed powder image from the selenium belt
surface to sheet material is effected by means of a corona transfer
device 19 that is located within the sheet transport mechanism to
the point of contact between the sheet and selenium belt. The
corotron 19 may include one or more corona discharge electrodes
that are energized from a suitable high potential source and extend
transversely across the selenium belt and are substantially
enclosed within a shielding member.
In operation, the electrostatic field created by the corona
discharge device 19 is effective to attract the toner particles
comprising the xerographic powder image from the belt surface and
cause them to adhere electrostatically to the surface of the sheet
material. As the powder image is being transferred to the sheet
material in a flowing manner, the sheet continues to adhere to the
selenium belt however, as the portion of the sheet passes the
transfer station C, the sheet is stripped from the conveyor belts
by means of a stripping device generally indicated by the reference
numeral 20. This device includes an AC corona discharge device
adapted to produce a charge which neutralizes that which causes the
sheet material to adhere to the selenium belt, and a manifold
supplied with a plurality of small outlets which when induced with
air pressure is effective to pull mechanically the paper off the
belt in cooperation with the corona discharge device.
As a sheet of paper leaves the sheet transport, it is conveyed into
a fuser assembly generally indicated by the reference numeral 21
wherein the developed and transferred xerographic powder image on
the sheet material is permanently affixed thereto. After fusing,
the finished copy is discharged from the apparatus at a suitable
point for collection externally of the apparatus. To accomplish
this there is provided a short horizontal conveyor 22 which conveys
a sheet of material out of the fuser assembly 21 and into a catch
tray 23 supported upon the machine frame.
The next and final station in the device is a belt cleaning station
having positioned therein a corona precleaning device 24 similar to
a corona charging device to impose an electrostatic charge on the
selenium belt and residual powder adherent thereto to aid in
effecting the removal of the powder, a belt cleaning assembly 25
including a rotating brush device adapted to remove any powder
remaining on the xerographic belt after transfer and a source of
light, in the form of lamp LMP-1, whereby the selenium belt 12 is
flooded with light to cause dissipation of any residual electrical
charge remaining on the xerographic drum.
Suitable drive means described hereinafter are arranged to drive
the selenium belt 12 in conjunction with timed flash exposure of an
original to be copied, to effect conveying and cascade of toner
material, to separate and feed sheets of paper and to transport the
same across the transfer station C and to convey the sheet of paper
through the fuser assembly in timed sequence to produce copies of
the original.
ILLUMINATION APPARATUS
The illumination assembly 10 is illustrated in detail in FIGS. 3-6
and is designed for irradiating the diffusely reflecting original D
such that the image of the original produced by a lens has
irradiance uniformity to a maximum of one per cent. This uniform
image irradiance is obtained by the orthogonal placement of four
linear light sources L.sub.1, L.sub.2, L.sub.3, L.sub.4, and is
enhanced by the use of the associated reflectors R.sub.1, R.sub.2,
R.sub.3 and R.sub.4. The arrangement is such as to compensate for
the relative illumination functions of the lens, for example, the
illumination falloff due to vignetting of the optical aperture for
the system and to the cosine to the fourth power law.
Each of the four linear light sources, which may be in the form of
a fluorescent lamp or other gaseous discharge tube, is provided
with two spaced apart reflectors one of which is elliptical and/or
other cylindrical. The radiometric equations for the elliptical and
the cylindrical reflectors are utilized to project reflected light
from a platen supporting an original onto an image plane where the
irradiated image has near perfect irradiance.
As shown in FIGS. 4 and 5, the lamps L.sub.1, L.sub.2, L.sub.3 and
L.sub.4 are arranged along the sides of a rectangle somewhat larger
than the rectangle defined by the original D. The inner edges of
the reflectors R.sub.1, R.sub.2, R.sub.3 and R.sub.4 being parallel
to the respective lamps are also arranged as the sides of a
rectangle having its inner edges spaced slightly outwardly from the
edges which define the original. With this arrangement, the light
rays which emanate from each of the lamps, are directed toward the
original, to impinge thereon at various angles other than directly
or at 90.degree.. This arrangement, then, eliminates direct
perpendicular impingement of the light rays upon the document
thereby preventing excessively high intensity illumination of the
edges of the document if such were extended over the light
sources.
With light sources being located beyond the corresponding edges of
the original D and, without the use of additional devices for
directing light rays from the sources, the light impinging upon the
document from the light source lamps would result in the
homogeneous illumination of the photoconductive surface, but with a
somewhat diminished intensity since much of the light emanating
from the lamps are directed away from the original. The orthogonal
relationship of the lamps located outside the outer edges of
originals will effect this homogeneous irradiance that is not
possible with an arrangement wherein only two sides of an original
are provided with a lamp.
In order to enhance the homogeneous illumination wherein there will
be a minimum amount of variation in the image irradiance from an
original and, to increase the amount of light that can be directed
toward the original D, the illumination system 10 is provided with
specifically shaped bireflective surfaces for each of the linear
lamps. These reflective surfaces are designed to direct light to
specific portions of the original being illuminated and are so
arranged that the impinging rays of one lamp and its corresponding
bireflective pair of surfaces overlap with the impinging rays of
the opposing lamp and its corresponding bireflective pair of
surfaces. These reflected rays coupled with the rays from each of
the lamps upon the original and result in a more uniform,
homogeneous illumination of the photoconductive surface.
Each of the reflectors, and for simplicity the reflector R.sub.1
will be the only one described in detail, comprises two reflecting
surfaces. The reflector R.sub.1 includes a first reflector surface
R.sub.a having a flat spacer portion 26 between two segments of
this surface and, is in the form of a right circular cylinder or,
an ellipse of unit eccentricity having the axis of the surface of
revolution or line foci coincident with the axis of the linear lamp
L.sub.1. The reflector surfaces R.sub.a, one for each of the
reflectors in the illumination system 10, define the inner limits
of the four assembled reflectors. When assembled, the surfaces
define an opening through which the light rays emanating from an
illuminated original are directed therethrough to a projection lens
for the document illumination system.
Joined along the outer edge of the reflector surface R.sub.a is a
second reflector surface R.sub.b in the form of an arc of an
ellipse with one of its foci, illustrated at point F, along the
line A.sub.1 A.sub.2 which represents a light ray trace to the
adjacent edge of the original D. One of the line foci for the
surface R.sub.a commences at the point F and extends for the full
length of the surface. This line foci is parallel to the edge of
the original D that has point A.sub.2 thereat. The other focus
point for the ellipsoid surface R.sub.b and therefore, its other
line foci, coincides with the point on L.sub.1, the lamp center
line. The light ray A.sub.1 A.sub.2 is produced by the reflection
of a light ray from the lamp L.sub.1 directed to the point A.sub.1.
Another light ray from the lamp L.sub.1 is shown being reflected by
the reflector surface R.sub.b at a point B.sub.1 and is reflected
to the opposite edge of the original D to a point B.sub.2. The
light rays A.sub.1 A.sub.2 and B.sub.1 B.sub.2 intersect at the
focus F, in fact, it is this positioning of the focus that results
in the positioning of the intersecting lines. Similar light rays
from the lamp L.sub.1 falling between the points A.sub.1 and
B.sub.1 on the surface R.sub.b will be reflected toward the
original at points between the points A.sub.2 and B.sub.2.
Similarly, each of the reflecting surfaces R.sub.b on the
reflectors R.sub.2, R.sub.3 and R.sub.4, the corresponding light
ray lines A.sub.1 A.sub.2 and B.sub.1 B.sub.2 will be limiting
light rays, that is, those light rays between which light rays will
be reflected onto a document.
With the axis of the linear light source L.sub.1 being the center
of revolution for the cylindrical reflecting surface R.sub.a, light
rays emanating from the light source and impinging upon this
reflecting surface will be directed to the original along different
lines. Light impinging at the point C.sub.1 on the surface R.sub.a
for instance will be directed to the point A.sub.2 on the original.
Another light ray from the lamp L.sub.1 impinging upon a point
E.sub.1 will be directed upon the point B.sub.2, the other side of
the document. Any other light ray impinging upon the reflecting
surface R.sub.a between the points C.sub.1 and E.sub.1 will be
reflected upon the original between the points A.sub.2 and
B.sub.2.
The segment of the surface R.sub.a closest to the inner edge of the
illumination assembly reflects light rays impinging thereon upon
the ellipsoid surface R.sub.b rather than reflecting directly
toward the document. For example, a light ray impinging upon the
point G.sub.1 will be directed to the point B.sub.1 and redirected
to the point B.sub.2 upon the document. Similarly, light impinging
upon point H.sub.1 will be directed to the point A.sub.1 whereupon
this light ray will be reflected to the point A.sub.2.
From the foregoing it will be apparent that the reflecting surfaces
R.sub.a and R.sub.b serve to reflect the light rays emanating from
the lamp L.sub.1 upon the original D between both extreme edges
thereof in overlapping fashion. This means the light reflected from
the surface R.sub.a will be directed upon the document starting
from the line coincident with the adjacent edge of the original,
that is, the line extending along the edge of the original starting
at point A.sub.2, and sweeping across the document to the other
edge thereof terminating in a line having its beginning at point
B.sub.2. Light reflected from the ellipsoid reflector R.sub.b is
directed upon the document between these identical lines, that is,
between lines beginning at A.sub.2 and B.sub.2, respectively. The
light rays reflected from the surface of the segment of the surface
R.sub.a nearest the adjacent edge of the original is reflected back
upon the ellipsoid reflector R.sub.b and reinforces the light
already directed upon this surface from the lamp L.sub.1 directly,
and from the outer segment of the surface R.sub.a.
Similarly, as viewed in FIG. 5, the reflector R.sub.3 serves to
reflect light from the lamp L.sub.3 upon the original D. The light
rays so reflected overlap those reflected from the reflecting
surfaces of the reflector R.sub.1. In similar fashion, light is
directed from the reflectors R.sub.2 and R.sub.4 by reflection from
the lamps L.sub.2 and L.sub.4, respectively, upon the original in
overlapping ray-trace arrangement.
The effect then, of the use of four orthogonally arranged lamps
arranged beyond the edges of an original being illuminated, and
especially with the provision of the specifically designed
reflecting surfaces for each of the reflectors and the relative
positions thereof, an original is illuminated in such a manner that
the object irradiance is cos.sup..sup.-4 or otherwise circularly
symmetrical for the center point of the surface of the original. It
will be apparent from this arrangement of reflecting surfaces that
the illumination apparatus 10 makes effective use of a large part
of the light flux emitted from the light sources except for those
areas wherein reflection losses are behind the lamps
themselves.
It will be appreciated that the arrangement of the lamps provides
cos.sup..sup.-4 illumination. By incorporating the illustrated
elliptical reflector R.sub.b with each of the lamps, the resultant
illumination profile for an object being illuminated is changed to
be symmetrical. The use of the right circular cylindrical surfaces
R.sub.a adds efficiency to the system.
Each of the lamps L.sub.1, L.sub.2, L.sub.3 and L.sub.4 is
connected to an electrical circuit for energizing these lamps. For
the particular reproduction machine illustrated in FIG. 2, the
particular electrical circuit for energizing the lamps is in the
form of a flashing circuit which will energize the lamps for short
periods of time, such as, for example, 100 microseconds. In this
particular use, this short period of time will be suitable for
flash exposing the original D upon a photoreceptor surface such,
for example, as the selenium belt 12, to be described
hereinafter.
The image forming light rays emanating from the original D during
illumination thereof are directed to a projection lens system
generally indicated by the reference numeral 30. For simplicity,
light rays from each of the four corners of the original will be
described and illustrated as an indication of the ray traces for
the illuminated original. The light rays from the four corners of
the original, illustrated at A.sub.2, B.sub.2, K.sub.2 and M.sub.2
in FIG. 3, are directed through the projection lens 30 onto a first
plane mirror 36 supported by brackets 37 within a mirror housing 38
secured to a suitable frame 39. The mirror is inclined at
approximately 45.degree. from the horizon for the vertically
oriented optical axis 0 of the projection lens. Light rays
reflected from the mirror 36 are directed upon a second plane
mirror 40 supported by clamps 41 to inside portions of the housing
38 and is arranged with its plane at 45.degree. to the optical axis
of the projection lens 30. The mirror 40 is also rotated 45.degree.
relative to the plane of the mirror 36 in order to direct image
rays therefrom along an optical axis normal to the optical axis 0
for the lens 30. The light rays reflected from the mirror 40 are
directed upon the photoconductor surface of the selenium belt 12
arranged so that the exposure section thereof is flat and,
positioned vertically and normal to the impinging leg of the
optical axis 0 for the image rays emanating from the mirror 40.
Each of the brackets 37, 41 are adapted to adjustably support their
respective mirrors 36, 40 in order to insure that the image rays
emanating from the document D will be directed centrally upon the
selenium belt 12 at the exposure station A. With the use of a
projection lens and two plane mirrors, the image formed upon the
surface of the belt 12 will be upright and wrong reading and will
expose the previously charged belt 12 for producing an
electrostatic latent image thereon.
The illumination assembly 10, by virtue of the illumination housing
31 and the mirror housing 38 both of which are light tight and
preferably coated with black paint or the like internally, will
prevent image light rays from being distorted and affected by any
external lighting. The assembly 10 is adapted to present light
image representation of an original upon the selenium belt 12
sequentially in timed relation to the movement of the belt which in
the particular xerographic reproduction apparatus to be described
hereinafter, continuously moves during the xerographic processing
stations. The light image of the original being reproduced, in
being reflected by the mirror 40 is directed out of the mirror
housing 38 through a suitable rectangular opening on the side of
the housing adjacent the selenium belt 12. The housing 38 then
serves as a light shield for the selenium belt in order to prevent
extraneous light from impinging upon a belt during use of the
apparatus.
PHOTOCONDUCTIVE BELT ASSEMBLY
(FIGS. 7-13)
The selenium belt comprises the photoconductive layer selenium
which is the light receiving surface and imaging medium for the
apparatus, on a conductive backing. The belt is journaled for
continuous movement upon three rollers 45, 46 and 47 located with
parallel axes at approximately the apex of a triangle. During
exposure of the belt 12, the portion thereof being exposed is that
part of the belt run between the upper roller 45 and the lower
roller 46. As shown in FIG. 7, the photoconductive belt assembly 11
is illustrated with the selenium belt removed in order to
illustrate the assembly mechanisms located adjacent the belt.
The upper and lower pulleys 45 and 47 are journaled in two side
plates 48 and 49, each having the general configuration of a
triangle. The upper apex of the side plate 48 is formed with an
opening for containing and supporting a bearing 50 which rotatably
supports one end of the shaft 51 for the roller 45. At the other
end, the shaft 51 is journaled in a bearing 52 supported at the
upper apex for the side plate 49 in the same manner; however, the
shaft extends beyond the side plate and through an opening 53
formed concentrically with the shaft in a main support plate 54 for
the reproduction apparatus. A shaft extension 55 is formed on this
end of the shaft and extends through the opening 53.
The purpose for the extension 55 of the shaft 51 is to support a
drive mechanism for rotating the roller 45 when the belt assembly
11 is in operating position, that is, when the side plate 49 is
positioned against the main frame plate 54, and still permit the
easy removal of the belt assembly 11 from the machine frame. To
this end, the main frame plate 54 is provided with a quick
disconnect mechanism for releasably receiving the extension 55 and
to become drivingly engaged with the extension when the assembly 11
is in operating position. As shown in FIG. 10, the opening 53 in
the frame plate 54 is covered on one side, the side removed from
the roller 45, by a support ring 56 suitably secured by bolts to
the remote side of the plate 54. The ring 56 is formed with an
opening 57 concentric with the opening 53 and the shaft 51 when in
operating position. Within the opening 57 is retained a bearing 58
having an inner race 60 secured by a lock ring 61 to a drive member
62 rotatably retained by the bearing 58 upon the plate 54. The
drive member 62 is formed with a concentrically positioned recess
63 into which is inserted the extreme end of the extension 55. This
end of the extension has a snug fit within the opening 63 and
serves to precisely locate the axis of the shaft 51 relative to the
support frame plate 54 thereby insuring accurate driving of the
selenium belt 12.
The driving connection between the shaft 51 and the drive member 62
is in the form of a one way clutch 64 drivingly connected between
the extension 55 and the member 62. The clutch 64 is adapted to
become engaged when the assembly 11 is in operating position in
order to permit rotation of the roller 45 by rotation of the drive
member 62. When the belt assembly 11 is slightly removed or pulled
away from the frame plate 54, the clutch 64 and the extension 55
are pulled out of the recess 63 in the drive member 62 in order to
disengage the connection therebetween.
The outer extremity of the drive member 62 is adapted to support a
drive gear 65 which meshes with a smaller gear 66 secured to a
pulley 67 drivingly connected by way of a timing belt 68 to a drive
system to be described hereinafter.
The side plates 48 and 49 are maintained in parallel planes and
rigidly supported in spaced relation for supporting the rollers 45,
46 and 47 and all of the other structures that comprise the belt
assembly 11 by an internal T-member to be described below. The side
plates 48, 49 also support a flat front plate 69 and a rear flat
plate 70 by suitable means such as screws 71. Each of the plates 69
and 70 are formed with a plurality of apertures 72 which extend
through the respective plates. As will be described in detail
hereinafter, the plates 69 and 70 serve as vacuum hold down plates
for supporting the selenium belt 12 flat against the plates during
movement thereof on the assembly 11. The apertures 72 are in
communication with a plenum chamber which, in turn, is connected by
suitable ducts to a vacuum chamber for drawing air inwardly through
the apertures 72 and thereby hold by vacuum the adjacent runs of
the belt 12.
The lower roller 47 is similarly mounted upon the side plates 48,
49 as is the left-hand end of the shaft 51 for the roller 45. The
shaft 73 for the roller 47 may be suitably supported in ball
bearings similar to bearing 50 supported in the side plates 48,
49.
As previously stated, the selenium belt assembly 11 is slidably
supported on the machine frame plate 54. To this end, the frame
plate 54 has extending horizontally and perpendicular thereto a
support arm 75 having a cross section shaped as the letter T.
Secured to the upper cross bar of the support arm 75 is the lower
race 76 of a slide suspension arm which also includes an upper race
77 secured to the upper leg of a T shaped channel member 78 secured
between and supporting the side plates 48, 49 of the belt assembly
11. The channel member 78 is approximately positioned within the
center space of the belt assembly and also has secured on one side
thereof a race 80 of another slide suspension arm which has its
other race 81 secured to the adjacent lower section of the support
arm 75. Upon viewing FIG. 11 it will be apparent that a belt
assembly 11 is adapted to be moved toward and away from the frame
plate 54 and to be supported thereon for sliding movement by the
support arm 75, the sliding characteristic being supplied by the
slide suspension arms comprising the races 76, 77 and 80, 81. When
mounted on the arm 75 in cantilever fashion, all of the mounting
means for the belt assembly are positioned within the confines of
the assembly as defined by the axes of the rollers 45, 46, 47. This
arrangement allows access to and clearance for the belt for
permitting removal or installation of the same without endangering
its structure.
The T-members 75 and 78 together with the slide suspension arms
connected therebetween and the shaft extension 55 and the drive
member 62, allows the belt assembly 11 to be removed and positioned
for support upon the fixed support plate 54 without disrupting or
requiring a drive connection and, to insure safe positioning of the
belt and the assembly. Guide slots 79 formed in the plate 54
receive locating pins secured to the plate 49 for precisely
locating the assembly 11 once it has been moved into operating
position.
Each of the side plates 48, 49 is formed with axially aligned
openings 82 in order to accommodate the support arm 75 during
mounting or removal of the assembly 11. These openings, only one of
which is shown, also serve to permit the extension therethrough of
a locking mechanism for releasably holding the assembly 11 upon the
plate 54 when the assembly has been moved thereto.
This locking mechanism includes a pair of blocks 83, 84 secured
within the chamber defined by the plates 48, 49 and one to each of
these plates. A shaft 85 is slidably received in the blocks 83, 84
and extends through the opening 82 formed in the plate 48 a short
distance to accommodate a handle 86 at that end thereof. The other
end of the shaft 85 extends through the other opening 82 formed in
the side plate 49 and extends beyond an opening formed in the frame
plate 54 in line with the opening 82. This end of the shaft 85
terminates in a bent portion 87 (see FIG. 8) which is adapted to be
moved to assume different radial directions upon rotation of the
shaft 85 by the handle 86. The bent portion 87 is adapted to be
received in a depression 88 formed in a circular lock member 89
secured upon the outer surface of the frame plate 54.
Normally, the shaft 85 is urged outwardly or to the right as viewed
in FIG. 10 by a spring 90 held in compression between the handle 86
and one side of the block 83. When the assembly 11 is removed from
the frame plate 54, the spring 90 will cause the bent portion 87 to
abut against the block 84. In order to lock the assembly 11 against
the plate 54 and assuming that the assembly 11 is properly oriented
upon the plate, the handle is pushed toward the adjacent side plate
48 in order to drive the bent portion 87 through the opening 82 in
the plate 49 and the adjacent opening in the frame plate 54.
Rotation of the handle while so depressed will rotate the bent
portion 87 in position to be in alignment with the depression 88
formed in the lock member 89. Upon release of the handle 86, the
spring 90 will force the shaft 85 outwardly thereby causing the
bent portion 87 to assume a locked position within the sides of the
depression 88. In this manner, the assembly 11 remains rigidly
locked in proper position and alignment upon the frame plate
54.
As previously stated, the apertures 72 formed in the vacuum plates
69 and 70 are in communication with plenum chambers which, in turn,
are connected to a vacuum manifold which is suitably connected to
an evacuation system, such as a blower and the like, in order to
produce a slight vacuum within the plenum chambers. As shown in
FIG. 11 the front or exposure side of the belt assembly 11 is
connected by means of end strips 92 to a rear base plate 93 mounted
parallel to but spaced slightly from the front vacuum plate 69. The
flat chamber formed between the plates 69 and 93 and the end strips
92 define a vacuum plenum having an outlet slot 94 (see FIG. 8)
which is arranged, when the assembly 11 is in locked position upon
the plates 54, to be in communication with an opening formed in the
plate 54. The edges of the slot 94 are gasketed so that when in
abutment with the adjacent surface of the frame plate 54 and in
alignment with a slot opening formed therein of a size and shape as
the opening 94, there will be a minimal amount of leakage of air
through these abutting surfaces.
The opening 94 may be suitably connected to a hose or manifold to a
suitable blower which would in operation evacuate air from the
plenum chamber and cause the flow of air inwardly through the
openings 72. This vacuum condition will cause the selenium belt 12
to be drawn against the plate 69 during movement of the belt during
processing by the machine. Since the plate 69 lies in alignment
with the exposure station for the selenium belt, it is imperative
that the selenium belt, as it moves across the station, be as flat
as possible so that light ray impinging upon the selenium belt at
this area will be in focus at all points.
Similarly, the rear vacuum plate 70 combines with a parallel spaced
base plate 96 and end strips 97 to form a second plenum chamber
which is also connected to a suitable opening in the base plate 54
and connected to a blower or vacuum producing apparatus. The rear
vacuum plate 70 and its related plenum structure is adapted to hold
the selenium belt in a flat plane on this side of the belt
assembly, which side is adjacent, as will be described hereinafter,
to a development apparatus which requires that the selenium belt be
or remain in a flat condition.
As previously stated, the selenium belt rollers 45 and 47 are
mounted for rotation upon the side plates 48, 49, being held
against any other movement relative to the side plates by suitable
mounting bearings. In order to permit the mounting and dismounting
of a selenium belt 12 upon the belt assembly 11, the assembly is
provided with an arrangement for moving the third roller 46
inwardly in order to form a slack in the belt 12 for permitting its
removal by sliding axially of the rollers. As part of this
arrangement, the roller 46 is rigidly secured upon a shaft 100, the
ends of which are each mounted within a self-aligning bearing
element 101 adapted to be secured to each support arm 102, 103.
Each of the support arms 102, 103 is arranged for longitudinal
movement for one operative function therefor and, for limited
rocking or slight pivotal movement for another operative function.
To this end, each of the support arms comprises a first slide
member 104 to which the bearing element 101 is secured for
supporting the roller 46 upon the belt assembly and a second slide
member 105 slidably mounted relative to the first member. In order
to accomplish sliding movement of one slide member relative to the
other, the member 104 is formed with an elongated depression 106
running along the longitudinal axis thereof and, within the
depression, the slide member 105 conforms and is held against
removal therefrom by suitable lock strips 107 mounted in parallel
to the adjacent edges of the member 104 in overlapping relationship
relative to adjacent edges of the member 105. When mounted
together, the members resemble a slide rule device which may be
elongated by extending the members.
The support arms 102, 103 are supported by pivot pins 108, each
securing one of the arms to the lower portion of the side plates
48, 49. Each pin 108 is rotatably fastened to the slide member 105
and is slidably related to the first member 104. This arrangement
has the affect of preventing axial movement of the second slide
member 105 while allowing sliding movement of the first member 104
relative to the second member.
Manually operated control means are provided for producing
simultaneous sliding movement of each first member relative to the
respective second member in order to move the roller 46 inwardly
relative to the belt assembly to permit the removal or installation
of the selenium belt 12. The end of the first member 104 remote
from the end thereof which supports the roller shaft 100 is
provided with a cam follower 109. As shown in FIG. 12, the follower
extends in a direction normal to the longitudinal axis of the
support arm 102 and has a lateral extending cam surface 110 adapted
to cooperate with a cam 111 formed as a semi-circular disc and
being mounted eccentrically relative to the semi-circular cam
surface 112 thereon. Each of the cams 111 is secured for rotation
upon a shaft 113 which in turn, is mounted for rotation on the side
plates 48, 49 of the belt assembly. In being secured to the shaft
113, the cam surface 112 for each of the cam plates 111 will be
moved in unison when the shaft is rotated and, upon rotation, will
simultaneously engage the camming surface 110 of each of the cam
followers 109.
Rotation is imparted to the shaft 113 by way of a manually actuable
handle 114 secured to one end of the shaft extending through the
side plate 48. As shown in full lines in FIG. 9, the handle 114 is
positioned such that the cam plates 110, as shown in FIG. 11, is
against the shortest camming position for the cam surfaces 110, in
fact, there is a slight spacing between the surface 110 and the
follower 109, thereby allowing the slide member 104 to be extended
outwardly to its maximum, belt supporting and tensioning limit.
When the handle 114 is moved to the dotted position in FIG. 9,
which corresponds to its full line position in FIG. 12, the cam
plates 111, being moved thereby, will contact the surface 110 and
drive the support member 104 along its longitudinal axis at its
high points to the position of the cam follower 109 as shown in
full lines in FIG. 12. With each slide member 104 being thereby
moved, the roller 46 is moved inwardly to the position shown in
FIG. 12. In this position of the roller, an operator may remove the
selenium belt 12, which will be in a loose condition, from the
selenium belt assembly 11.
Normally the support slide member 104 is held in its outermost
maximum belt tensioning limit by means of a pair of relatively
stiff springs 115 each having one end secured to a post 116 secured
to the member 104 and their other ends secured to a post 117
secured to the support member 105. The post 117 extends through a
slot 118 formed in the support member 104 being arranged to permit
extension of the post 117 therethrough and movement of support
member 104 relative to the post 117. Normally the springs 115 are
held extended between the post 116, 117 thereby normally
maintaining the slide members 104, 105 toward their extended
position.
This arrangement places a spring bias upon the supporting shaft 100
for the roller 46 toward its fully extended position during
operation of the belt assembly. The springs 115 therefore also
serve to place appreciable tension upon the selenium belt 12 during
movement thereof on the belt assembly. In the event that the
photoconductive belt is to be removed and replaced by another belt,
the operator manipulates the handle 114 from the position shown in
dotted lines to the position shown in full lines in FIG. 12 thereby
actuating the support member 104 inwardly against the bias provided
by the springs 115. This movement is accomplished rather smoothly
with the shaft 100 being moved from its outermost operative
position to its most inwardmost position that is parallel to the
operative position.
Each of the support arms 102, 103 is adapted to be rotated about
its respective pivit pin 108 and in opposite directions in order to
rock the shaft 100 in a plane normal to the plane defined by axes
of the support arms. This rocking movement is provided in order to
permit tracking of the selenium belt during its continuous movement
around its three support rollers. This tracking capability is
provided in order to maintain the belt in a precise predetermined
position for all xerographic stations surrounding the belt assembly
11 when in operation. The tracking is accomplished by mechanisms
which are adapted to slightly pivot each of the arms 102, 103 in
opposite directions about their respective pivot pins 108, as
previously stated.
As shown in FIG. 12, the end of each slide member 105 remote from
the end adjacent the shaft 100 is formed as a yoke element 120 that
is in alignment with the longitudinal axis of the slide member.
This end of each support arm is also formed with a slot 121 having
its longitudinal axis normal to thelongitudinal axis of the member
105. Each slot is adapted to accommodate a screw 122 having its
threaded portion secured into the inner surface of the plates 48,
49 of the belt assembly 11. Portions of the screws 122 that are
cooperable with the sides of the slots 121 are free of threads and
serve to maintain the arms 102, 103 against the side plates for the
selenium belt assembly. The inner edges of the yoke element 120 are
formed with camming surfaces 123 and 124 held in abutment against a
cam shaft 128 which extends through the belt assembly 11 and is
mounted in suitable bearings 130 secured to the side plates 48,
49.
As shown in FIGS. 10 and 11, the shaft 128 has its on-axis end
portions 131 mounted in the bearings 130 and portions 132 eccentric
relative to the main portion of the shaft. Each eccentric portion
132 is adapted to engage one or the other of the camming surfaces
123, 124. Upon rotation of the shaft 128 in either direction, each
eccentric portion is adapted to drive the corresponding yoke member
120 laterally in opposite directions in order to pivot the
corresponding support arm 102, 103 about their respective pivots in
opposite rotational directions thereby effecting opposite movements
to each end of the shaft 100.
In order to provide movement of both ends of the shaft 100 in
opposite directions thereby effecting a greater available movement
to the roller 46 the eccentricity of the cam portions 132 are in
opposite directions. Upon rotation of the shaft 128, the axis of
the main portion thereof will remain fixed and will move the cams
132 in the same direction to effect corresponding pressures upon
one of the camming surfaces 123, 124 in opposite directions, that
is, the camming surface 123 for one of the support arms 102, 103
will be moved in one direction, and the camming surface 124 of the
other arm will be moved in the opposite direction. The effect of
this opposite directional movement of the support arms 102, 103
will produce rocking movement of the shaft 100 and consequently the
roller 46. The spherical bearings upon which the shaft 100 is
mounted will permit this slight relative rocking movement of each
end of the shaft relative to its fixed mounting arrangement in the
form of the members 104.
As shown in FIG. 11 the axes of the shaft 100, the pins 108 and the
shaft 128 for the support arm 102 are in alignment and, for both
arms 102, 103 these axes lie in a common plane. This plane is in
coincidence with the bisector of the angle formed between the
planes of the belt runs on either side of the roller or, in other
words between the plane defined by the axes of the shafts 100 and
73 and the plane defined by the axes of the shaft 100 and the shaft
51. With the support arms 102, 103 being equally pivotable in
opposite direction the roller 46, during tracking operation, will
rock about an axis lying on the bisector plane and positioned
intermediate the ends of the roller. For tracking then, such skew
action of the roller will effect an angular relationship of the
roller relative to the direction movement of the belt thereby
causing the same to steer or follow the roller surface and be
displaced laterally in order to return the belt back to a centered
position rather than exerting pressure on the belt adjacent one
edge portion thereof. In this manner pressure is applied equally to
all portions of the belt affected during tracking action thereby
minimizing the tendency of the tracking arrangement to adversely
affect belt structure by exerting undue pressures of the belt
structure adjacent one edge of the portion between the midline of
the belt and one edge. With the axis of pivoting of the roller 46
lying on the bisecting plane for the planes of the selenium belt
runs, the deflection of the ends of the roller occurs in opposite
direction to provide maximum belt correction with minimum roller
skewing. Preferably the roller 46 is covered with a rubber coating
which will prevent slippage of the belt as it steers during
tracking. During rocking of the shaft 100, both edges of the belt
are affected equally and, as skewing increases during tracking
action, any tendency of the belt to lessen in circumference will
cause movement of the roller 46 inwardly against the tension of the
springs 115 which serve as shock absorbers for tracking action.
In the event that the selenium belt 12 is removed and a new one
applied to the belt assembly which has a slightly larger or smaller
circumference, the springs 115 will always maintain the same
pressure of the roller 46 upon the belt thereby insuring the same
tension upon a belt regardless of its circumferential size. The
arrangement also eliminates any two-directional forces being
applied to the belt which could have a destructive effect upon the
relatively thin film of the photoconductive material on the belt.
In addition, with the axis of the roller 46, lying on the bisecting
plane of the angle between the adjacent belt runs during rocking
movement of the roller 46, there is a minimum of deflection, caused
by skewing of the belt, along the exposure belt run between the
rollers 45, 46 thereby minimizing the effect of belt skewing upon
the imaging abilities on this run during an exposure of an
original.
Drive means are provided in the belt assembly 11 in order to impart
controlled instantaneous rotation of the shaft 128 in either
direction depending upon the slipping of the belt axially relative
to the shafts of the rollers 45, 46, 47 in either direction. The
shaft 128 has its end portion 131 extending through the side plate
49 and terminating in a gear 133 secured thereto. The gear 133 is
in mesh with a second gear 134 secured to a shaft 135 for a
reversible motor M-11 and gear reduction arrangement 136.
Energization of the motor M-11 will impart rotation to the gears
133,134 for rotating the shaft 128 in either direction depending
which direction the belt 12 slips relative to supporting
rollers.
Energization of the motor is accomplished by means of a sensing
device comprising a potentiometer POT (not shown) having a sensing
finger positioned adjacent an edge of the belt 12. In the event the
belt strays the potentiometer and its associated circuitry will
produce a signal to cause energization of the motor M-11 and
rotation thereof in a direction to cause the roller 46 to rock into
a position to force the belt back toward the direction opposite the
slipping direction.
DEVELOPER ASSEMBLY
In order to effect development of the electrostatic latent image on
the selenium belt 12, the development system for the xerographic
reproduction machine, shown in FIG. 2, includes a developer
assembly 14 (see FIGS. 13-27) which coacts with the selenium belt
12 at the development zone B along the rear vacuum plate 72 of the
belt assembly 11. At this development zone, the charged exposed
surface of the belt 12 is developed to form a powdered toner image
of the original that was previously illuminated.
For this purpose, the developer assembly 14 is mounted adjacent to
the belt assembly 11 to establish the development zone B. Mounted
within the developer assembly 14 is a screw conveyor arrangement
utilized in conjunction with an internal bucket conveyor belt for
continuously circulating developer material previously supplied to
the upper end of the developer assembly and from where the
developer material is cascaded over the now inclined upperly moving
selenium belt 12 in order to accomplish development of the latent
image thereon. As the developer material cascades over the flat run
of the belt 12, toner particles of the developing material adhere
electrostatically to the previously formed electrostatic latent
image areas on the belt, the remaining developer material falling
off the lower portion of the belt assembly adjacent the roller 47
or the peripheral surface thereof to be deflected by suitable
baffle plates into the bottom sump of the developer assembly 14.
Toner particles consumed during the developing operation to form
the visible powder toned image is replenished by the toner
dispenser 15 mounted external to the developer assembly.
Specifically, the developing assembly 14 includes an elongated,
vertically inclined, boxlike developer housing 200 having a top
wall 201, a bottom wall 202 in the form of a toner pick-off baffle,
side walls 203 and 204, a front wall 205, and a rear wall 206. As
shown in FIGS. 13 and 18, the side walls 203 and 204 are shaped
with a vertically inclined straight edge portion and a lower curved
portion in conformity with the shape the selenium belt 12 assumes
during the development function of the machine, as defined by the
vacuum plate 70 and the adjacent portions of the belt roller 47 to
permit the developer housing to be positioned closely adjacent to
the belt. Secured to the inside faces of the side walls 203 and 204
are side baffle plates 207 which support upon and hold against the
respective side plates a packing material in the form of strips 208
which extend slightly toward and against the selenium belt when the
developer housing 200 is in operating position in order to prevent
excessive dust and air currents from circulating within the
developer zone adjacent the belt during a developing function. In
effect, the packing strips 208 conform to the shape of the belt 12
and may be depressed slightly as the case of a sealing element in
order to form a powder tight seal between the developer housing 200
and the photoconductor belt 12.
In order to be disposed for high quality reproduction, the
developing assembly is capable of accomplishing line copy
development and solid area development. This is made available by
use of a development electrode 210 mounted upon the housing 200 as
the front wall 205. The development electrode 210 is positioned so
as to assume a spaced relationship relative to the adjacent run of
the selenium belt or that run when the belt is held against the
rear vacuum plate 70. The development electrode is shaped as a thin
wall rectangular plate and includes a thinner walled narrow
extension plate 211 which serves as an entrance chute for developer
material and which is mounted on but electrically insulated from
the top edge of the main electrode plate 210.
Means are provided for mounting the development electrode such that
the electrode may be individually adjusted at each of the corners
thereof in order to insure exact spacing of the electrode relative
to the selenium belt at all points thereon. Since all four of these
devices are exactly the same, only one of them will be described in
detail. In FIG. 18, the electrode 210 is shown as being formed with
a recess 212 for rigidly supporting a bearing block 213 into which
is positioned a spherical knob 214 having a screw shank 215 secured
thereto and being threadedly received in a supporting block 216.
The support blocks 216 used in supporting the electrode 210 may be
suitably secured to the side plates 203, 204 of the developer
housing and are suitably insulated relative thereto. A lock plate
217 is secured to the inner surface of the electrode 210 in a
position to overlie the recess 214 and, is formed with an opening
through which the threaded shank 215 projects.
This arrangement secures the knob 214 and shank 215 to the
development electrode but allows a limited rotary or universal
pivoting movement of the shank 215. The shank portion 215 is
adapted to receive a nut 218 which bears against the surface of the
support block 216 thereby serving as a means for axially moving the
shank 215 for positioning this particular corner of the development
electrode 210 relative to the fixed support block 216. The
electrode adjustment device is provided on each four corners of the
development electrode 210 thereby providing individual adjustment
means for the electrode.
During the developing function, development material comprising
very small diameter carrier beads having smaller toner particles
electrostatically adhering thereto, is introduced in the space
between the development electrode 210 and the adjacent run of the
selenium belt 12. As will be described more fully hereinafter, the
development material is introduced along a thin slot formed between
the belt 12 and the adjacent longitudinal edge of a plate 220
secured in the upper region of the developer housing 200. The
development material then is cascaded downwardly and enters the
space between the tapered portion 221 at the upper edge of the
electrode entrance chute 211 which, as observed in FIG. 18, is
spaced at a slightly greater distance from the belt 12 than is the
lower main portion of the electrode. The development material then
falls freely between the electrode portions and the selenium belt
during which time and distance the toner particles are pulled away
from the carrier beads by action of the electrostatic charged image
on the belt 12.
In order to enhance high quality development of the electrostatic
latent image, it is desirable that the electric lines of force be
drawn from the image itself with equal effect. Since development of
latent image depends upon field strength and time within the
developing zone, and field strength is a function of area charge or
charge density, the areas of the latent image possess varying
charge densities depending upon and related to the light pattern
produced during the illumination stage of the reproduction cycle.
In order to develop areas in proportion to their charge densities,
it is necessary to create an external field strength pattern
corresponding to the charge pattern on the plate surface. This
field pair is created by the use of the development electrode 210
being properly spaced uniformly relative to the adjacent run of the
selenium belt and the amount of electrical potential applied to the
electrode. This spacing results in equal representation of field
strength over areas of the electrostatic latent image having equal
charges and proportionately different representations over
proportionately different charged areas of the image. Since
development time is the same over all areas on the selenium belt
and inasmuch as field strength extended outwardly from this surface
is proportional to the charge pattern, then the developed image is
a true representation of the existing charge pattern.
Preferably, the development electrode 210 is spaced as close as
possible taking in consideration that the spacing between electrode
and the selenium belt 12 influences the electrostatic field
strength and must be such that the cascading development material
has sufficient spacing to be free to fall in cascading motion
therebetween. This spacing is also arranged as a factor of the
strength of the charge pattern in the latent image itself. For
relatively high charges, a greater spacing may be possible.
The free-flowing cascading movement of the development material is
relatively fast since the fall is at a relatively small angle
relative to the vertical. This developer material movement results
in a reduction in pressure in the development zone that encompasses
the entire area of the development electrode. This reduction in
pressure has a tendency to draw the selenium belt closer to the
development electrode. However, in view of the provision of the
vacuum producing device and the vacuum plate 70 immediately behind
the selenium belt, the latter is held against the vacuum plate in
order to maintain uniform spacing at all times for the belt as it
travels in continuous motion around the belt assembly. As will be
described hereinafter, the selenium belt is charged with a
potential of approximately 800 volts and when areas are discharged
thereon after the exposure function, the background areas which
become discharged may possess a residual charge of anywhere from 0
to 50 volts. Generally the full charge remains on the image areas,
that is, 800 volts or slightly less.
The development electrode 210 causes the lines of force from the
charged areas to be directed in general parallel relationship
toward the electrode and in perpendicular relationship to the image
surface. This results in uniform inherence of the developer toner
powder over the image area and produces a uniformly dark or
concentrated image with lines that are not diffused as
distinguished from powder developing devices in which there is no
development electrode and in which the lines of force from the
edges or outer portions of the high charged image areas are
consequently directed in curved paths to the adjacent discharged or
background areas resulting in the lines of force being dissipated
from the image area and producing black or dark effects around the
edges and light or white effects at the central portions of the
normally solid areas.
A potential is applied to the development electrode 210 and another
potential to the entrance chute 211 by a circuit to be described
hereinafter in order to maintain a bias on the electrode elements
of approximately 80 to 100 volts with the polarity the same as that
of the charged image areas and which is at a greater voltage but of
the same polarity as the charge on the background areas. In this
manner, the residual charge on the background areas are neutralized
and the electrode 210 prevents toner particles from adhering to the
background areas. In effect, the resultant transferred image upon
support material such as a sheet of paper will be relatively free
of background toner particles thereby enhancing the contrast and
improving the quality of the resultant reproduced copies.
Denuded carrier particles and other toner particles which were not
employed in developing the latent image and which have passed into
the lower spacing between the plate 210 and the belt 12 are
deflected upon the pick-off baffle 202 which is electrically biased
and carries the particles back into a conveyor system for the
development material. These particles are conveyed to a chute 223
extending across the entire width of the housing 200 and being
suitably mounted on the side plates 203, 204 thereof. The toner
particles and denuded carrier particles are directed by the chute
223 into a developer material return system comprising a first
conveyor screw arrangement for conveying development material that
has been cascaded over the surface of the belt 12, an internal
bucket vertical conveying belt for conveying this material
vertically to a position above the entrance chute 211 for the
development electrode 210 and, a second conveyor screw for
conveying the development material horizontally from the internal
bucket conveyor belt to position developer in a sump which is in
communication with the upper reaches of the spacing between the
development electrode and the belt 12 preparatory to continuous
recascading of the material across the selenium belt 12. The chute
223 directs developer material through an elongated slot 224 formed
in a lower conveyor tube 225 secured to the side plates 203, 204
and extending out of the housing 200. The tube 225 houses a screw
conveyor 226 which is continuously rotated during operation of the
developer assembly and which functions to convey developer material
horizontally out of the developer housing 200 and into a vertical
return system.
Developer material is conveyed out of the developer housing 200 and
into a developer return housing 227 mounted in spaced relation and
parallel to the side plate 203 for the housing 200. The developer
return housing has an elongated configuration, the axis of which is
in alignment approximately with the planar format of the developer
housing, that is, slightly inclined relative to the vertical. The
screw conveyor 226 is mounted on a shaft 228 that has one end
mounted for rotation in bearing 230 secured to an end wall 204 of
the developer housing and the other end rotatably mounted in a
bearing 231 secured in a hub 232 which, in turn, is secured to the
inner surface of the conveyor tube 225 at that end thereof
positioned within the return housing 227. As will be described
hereinafter, a drive mechanism for the screw conveyor 226 is
provided for this function and other driving functions relative to
the developer return system.
Developer material being conveyed by the screw 226 is carried
within the housing 227 and to an opening 234 formed in the lower
portion of the tube 225 within the housing 227. The opening 234
permits the egress of the developer material from the tube and
directs the material into any one of a plurality of internal
buckets 235 formed as part of an internal bucket conveyor belt 236
which encircles the tube 225 at this point.
The conveyor belt 236 is constructed so that its internally
directed buckets 235 are slightly longer in length than the egress
opening 234 to insure a minimum of loss of developer material. The
construction of the belt 236 is shown in greater detail in FIGS.
21-24 and, as illustrated, it will be appreciated that the belt is
constructed as a unitary element that may be fabricated as an
integral unit by a suitable molding process. The belt 236 is
relatively wide and is constructed as an endless conveyor utilizing
a plurality of internal buckets 235 each of which has a length
approximately two-thirds the width of the belt. Formed internally
along each of the outer edges of the belt for the entire
circumference thereof are evenly spaced teeth 237 which are
arranged for use as timing belts 238 for driving the conveyor belt
236 during conveying of the developer material.
Each of the internal buckets is defined by a circular wall 240, one
on each side of the belt between the buckets and the adjacent
timing belt. During construction of the belt 236, it is preferable
that the timing belts 238, the circular walls 240, and the buckets
235 are fabricated as a unitary structure. The portion of the
circular walls 240 located at the end of each bucket is formed with
a fanfold construction comprising small triangular shaped panel
walls 241, 242 for each end of a bucket 235. The panel sections are
adapted to be flexed relative to each other along flexure lines 243
formed in the circular wall and, each of the panels 241 is adapted
to flex inwardly along a line 244 formed at each end of a bucket.
This flexure occurs for both of the circular walls 240 when the
conveyor belt 236 is driven around the tube 225 for the screw
conveyor 226. As shown in FIG. 17, as the buckets 235 are driven
around the tube, the entrance slots for the buckets become more
narrow since they are assuming a smaller circumference than the
outer portions of the buckets adjacent the outer-most portions of
the belt. In order to prevent compaction of the material contained
in each of the buckets as the entrance slots therefor become
smaller, the amount of developer material allowed to enter a bucket
is held to approximately two-thirds of its total volume. During
movement of the belt around the tube 225, the panels 241 and 242
will deflect slightly inwardly without causing compaction of the
material therein in order to prevent the lateral lengthening of the
buckets with the consequent bending of the material comprising the
walls 240 against supporting pulleys therefor.
As the developing material is directed into the buckets 235, the
belt 236 continuously moves in the direction shown by the arrow in
FIG. 17 to bring the development material to a higher point above
that in which cascade upon the selenium belt 12 will occur. Upon
reaching its uppermost point, each of the buckets are drawn around
a conveyor tube 245 extending through the return housing 227
through a slot 246 formed in the upper portion of the tube. As the
buckets 235 are moved upwardly and around the tube 245 and when the
opening slots of the buckets are in register with the opening 246,
the development material is adapted to be poured from each of the
buckets and into the interior of the tube 245.
The tube 245 is similar to the tube 225 and serves to contain a
conveyor screw 247 which serves to convey developing material
horizontally from the developer return housing 227 and into the
developer housing 200 preparatory to movement of the developer
material into cascading position. The screw 247 is mounted for
rotation upon a shaft 248 supported in a bearing 249 mounted in the
end plate 204 and a bearing 251 secured in a hub 252 mounted on the
internal surface of the end of the tube 245. The shafts 228 and 248
for the screw conveyors 226 and 247, respectively, are parallel to
each other and preferably, have their axes in a plane parallel to
the plane of the selenium belt 12. During operation of the
developer assembly, the lower conveyor screw 226 and the upper
conveyor screw 247 are driven in unison in opposite directions and,
are adapted to convey each in its own direction as indicated by the
arrow, approximately the same quantity of development material in
order to prevent the advancement of movement of development
material of one of the screw conveyors over the other.
In order to effect vertical continuous movement of the developer
material from the sump of the developing housing and into a higher
position by means of the conveyor belt 236, there is provided a
pair of pulleys 253, 254 arranged around conveyor screw 226 for the
lower end of belt 236 and, a second pair of pulleys 255, 256
arranged around the conveyor screw 247 for the upper end of the
conveyor belt. The lower pulleys 253, 254 are arranged co-axially
in spaced relation by a cylindrical cage element 257. The spacing
of the lower pulleys 253, 254 are slightly greater than the length
of the buckets 235 and are formed as of timing pulleys engageable
with the timing belts 238 formed on each edge of the conveyor belt
236. Similarly, the timing pulleys 255 and 256 are held apart in
spaced relation upon a cage element 258 and engage the timing belt
238. Each of the cage elements 257 and 258 are formed as rods 259
(see FIG. 17) radially extending from the axis of a shaft 228 and
evenly spaced therefrom to provide fairly large openings
therebetween. The rods 259 are preferably made integral with the
spaced pulleys which they separate in parallel relationship.
Similarly, the upper cage element 258 is formed as a
semi-cylindrical thin walled element which may be made integral
with the adjacent sides of the pulleys 255, 256.
In order to impart movement to the belt 236 for producing conveying
action, the lower outside pulley 254 is formed with an annular hub
260 which extends through a suitable opening in the side plate of
the housing 227. A driven pulley 261 is fastened by screws to the
hub 260 and is connected by a timing belt 262 to a smaller pulley
263 secured to a shaft 264 mounted by brackets 265 on the developer
housing 200. The shaft 264, in turn, is connected to a drive system
to be described in detail hereinafter.
The driven pulley 261 and the lower pulleys 253, 254 are supported
for rotation upon the tube 225 by a pair of bearings 266 one of
which is positioned between the pulley 253 and the tube and, the
other, positioned between the driven pulley 261 and the outer end
of the tube 225. In order to prevent the leakage of developer
material out of the housing 227, the opening through which the hub
260 projects outwardly is surrounded by a sealing device 267 held
onto the outside wall of the housing 227 by a cover plate 268. At
the other side of the housing 227 an O-ring 269 is suitably locked
in position encircling the tube 225 and against metallic lock rings
which hold the tube 225 in position relative to that side of the
housing 227.
The upper conveyor belt pulleys 255 and 256 are mounted for
rotation upon the tube 245 by a pair of bearings 270 mounted
between the external surfaces of the tube 245 and the pulleys. This
arrangement permits unobstructed free rotation of the pulleys 255
and 256 relative to the tube 245 and the conveyor screw 247. A
threaded thimble 271 serves to lock to the outer bearing to the
tube 245 and to compress a suitable sealing device 272 between the
tube 245 and the side of the housing 227 in order to prevent
leakage of developer material through the opening in the side wall
occasioned by the protrusion of the tube.
It will be apparent that rotation of the driven pulley 261 will
produce rotation of the lower conveyor pulleys 253, 254 to cause
movement of the conveyor belt 236. In operation of the development
return system, both of the pulley arrangements 253, 254 and 255,
256 are driven in unison in order to convey development material
out of the tube 225 after the material has been cascaded across the
selenium belt 12 and to convey the material vertically to a higher
point to the interior of the upper tube 245. The material is poured
from each of the buckets 235 in the belt 236 and through the
opening 246 into the interior of the tube 245 whereupon the
development material is conveyed horizontally to be spread across
the entire length of a longitudinal slot 273 formed in a lower
region of the tube 245 that extends into the developer housing
200.
Rotation of the conveyor screws 226 and 246 is imparted by means of
a lower sprocket 274 connected to the outer end of the lower shaft
220 and an upper sprocket 275 of equal diameter, connected to the
outer end of the screw shaft 248. A chain 276 is arranged around
the sprockets 274, 275 for causing the same rotative movement of
the screws. A drive pulley 277 is also secured to the lower
conveyor shaft 228 and is connected by a timing belt 278 to a drive
system to be described hereinafter.
From the foregoing description of the developer material return
system, it will be appreciated that the system is adapted to
retrieve previously cascaded development material and to convey the
same horizontally, that is, perpendicular in direction to the free
fall cascading motion of the development material, thence to convey
the material vertically in a line perpendicular to the previous
stage of horizontal and conveyance, to bring the development
material to a higher level preparatory to the cascading action.
After the development material is brought to a higher plane, it is
once again conveyed horizontally and positioned to assume a
continuous relatively long, flat sheet or shower of fallen
developer material which disposed for cascading action over the
selenium belt 12.
As the development material is poured out of the slot 273 (see FIG.
18) the material is directed into an elongated hopper 280 mounted
upon the upper plate 220 in the upper region of the developer
housing 200. The hopper 280 extends across the entire width of the
housing 200 and is defined by an inclined top wall 281, a curved
bottom wall 282 and a deflection plate 283 for directing the flow
of most of the developer material from slot 273 and into the long
narrow passageway 284 defined by the walls 281, 282. Some of the
developer material as it leaves the deflection plate 283, is
carried upon the other side of the curved plate 282 remote from the
passageway 284 in order to permit some of the development material
to fall by gravity through an opening 285 formed in the support
plate 220 for purposes to be described hereinafter.
The development material leaving the passageway 284 continues its
downward movement and flows between one edge of the plate 220 and a
control plate 286 which is relatively narrow and extends across the
entire width of the housing 200. The plate 286 is in the same plane
as the out surface of the development electrode 205 and is formed
with a lower tapered edge 287 that cooperates with the tapered edge
portion 221 of the electrode entrance chute 211. Developer material
in passing between the edge of the plate 220 and the opposite side
of the plate 286 slides down the tapered portion 287 and into the
region between it and the tapered edge 221 and then between the
chute 211 and the selenium belt in position to begin the cascade
development function. The developer material falls in the form of a
thin, wide sheet of falling particulate material to be influenced
by the electrical charge on the belt 12 and the field charge
between the belt and the electrode 210. The plate 286 may be raised
or lowered in order to vary the spacing between the tapered edge
287 and the cooperating adjacent tapered edge 221 to control the
amount of developer material that is permitted to fall between
itself and the chute.
Positioning of the control plate 286 is provided by a movable plate
290 positioned across the width of the development housing 200 and
approximately in the same plane as the control plate 286 which is
connected along one edge thereof. The upper edge and ends of the
plate 290 are provided with tongues 291 carrying pins 292
insertable in slots 293 formed in plates 294 secured to and
positioned inwardly of the plates 202, 203. At the lower tapered
edge 287 of the control gate 286, there is formed at each end
thereof a strap 295 having its free end formed with a suitable
opening through which screw 296 extends and is fastened and
received in a slot 297 for permitting the smooth control movement
of the gate 286 along its plane. The screw 296 is arranged to
position the tapered edge 287 closer or further away from the
adjacent tapered edge of the chute 211 in order to control the
amount of development material flowing therebetween. The cam screw
296 also carries a locking nut in order to lock the gate 286 in a
desirable adjusted position.
The flow of developer material through the passageway 284 is under
control of a gate member 298 mounted for movement toward and away
from the plate 220 for controlling the amount of developer material
that may reach the space between the opposing tapered edges 221 and
287. Planar movement of the gate 298 is accomplished by means of
cam screw 299 made cooperable with the edges of a slot and which
not only supports the gate 298 but also serves to place the lower
edge thereof in abutment against the top surface of the plate 220
or to provide sufficient spacing therebetween in order to permit
full egress of developer material from the hopper 280.
TONER DISPENSER
As the developing mixture is cascaded over the xerographic belt 12,
toner particles are pulled away from the carrier beads and
deposited on the belt to form powder images, while the partially
denuded carrier beads and excess toner pass off the belt and into
the developer housing 200 by way of the pick-off baffle 202 as
previously described. As toner powder images are formed especially
for solid area development additional toner particles must be
supplied to the developing mixture in proportion to the amount of
toner deposited on the selenium belt. To supply additional toner
particles to the developing mixture, the toner dispensing system 15
is utilized to accurately meter toner to the developing mixture
within the lower portion of the developer housing 200.
Referring now to FIGS. 16, 18, 25 and 26, toner dispenser 15
comprises a hopper or toner container 300 into which is contained a
relatively large supply of toner particles that may be poured into
the container from an external source through a suitable cover
301.
The container 300 is formed as a truncated bin having a lower
discharge nozzle section 302 through which toner is fed into the
lower conveyor tube 225. Control of the flow of toner in accordance
with the density characteristic of developed images is in the form
of a toner plate 303 and a metering gate 304, the latter being
mounted for reciprocatory movement across the lower opening of the
nozzle 302.
The metering gate 304 is mounted in a carriage 305 which is mounted
for reciprocatory movement in order to move the metering gate 304
relative to the toner plate 303 and thereby produce controlled flow
of toner from the container 300 into the lower conveyor tube
225.
The container 300 rests upon a frame structure 306 which has a
slightly enlarged, generally rectangular shape similar to that of
the nozzle section 302. Actually the nozzle section 302 fits into
the interior of the frame structure which comprises longitudinally
extending side frame elements 307, 308 and end elements 309. The
lower edges of the side elements 309 are formed with circular edges
310 adapted to rest upon adjacent circular end edges of the opening
224 as formed in lower conveyor tube 225 and may be arranged to
prevent the leakage of toner material between the edge 310 and the
tube during flowing of the toner particles.
The end elements 309 are also formed with deep recesses which
terminate in a flat plane surface 311 having a width slightly
larger than the width of the toner plate 303 and which accommodate
the ends of this plate. Each end of the plate 303 is provided with
adjusting set screws 312 which are suitably rotated to position the
corresponding end of the plate 303 relative to the surface 311. A
lock screw 313 is slidably received through a suitable opening in
each end of the plate 303 and adapted to be threadedly received in
a tapered opening formed in the lower section of each of the end
elements 309. The set screw 313 is formed with a shoulder
engageable with the top surface of the plate 303 and when turned
down serves to lock the plate upon the surface 311, being spaced
therefrom by the set screws 312. The set screws 312 serve as
adjusting devices for the plates 303 in relation to the relatively
fixed metering plate 304 in order to maintain the spacing between
these plates at a predetermined distance which may be set in
accordance with the toner material and the diameter of the
individual particles thereof.
As previously stated, the carriage 305 is mounted for reciprocatory
motion relative to the nozzle section 302 for imparting
corresponding motion to the metering gate 304. In order to
accomplish this reciprocatory motion the frame structure 306 is
provided with a pair of guide rods 314 mounted with their axes in
parallel, in spaced relation on either side of the nozzle section
302 and slightly above the position of the gate. The rods 314 are
suitably retained within apertures formed on both of the end
elements 309. As shown in FIG. 25, the carriage 305 includes end
slide elements 315 which are connected at the ends of a
longitudinally extending frame 316 to which the metering gate 304
is attached. The frame 316 is also provided with a rear upstanding
slide element 317 through which the rear guide rod 314 extends. The
rods 314 support the carriage 305 by means of the two end elements
315 and the rear element 317 in a sliding relationship in order to
permit reciprocatory motion by the carriage.
In order to impart motion to the carriage 305, a front frame
section of the frame 316 is provided with a vertically extending
slot 318 formed in a central portion between the end elements 315.
The slot 318 is adapted to slidably receive a drive pin 320 secured
off center relative to a rotatable drive element 321 which in turn
is secured to the drive shaft 322 extending from a gear reduction
box 323 which derives its power from a motor M-10. Upon
energization of the motor M-10, the gear box 323 imparts motive
force to the drive element 321 for producing circular orbital
movement of the drive pin 320. Since the drive pin 320 is confined
within the vertical slot 318, as the pin orbits, the carriage 305
will reciprocate in a horizontal plane a total distance equal to
the diameter of the orbital movement of the pin 320. Energization
of the motor M-10 for this purpose is under control of a toner
sensor control to be described hereinafter.
The toner container 300 is also provided with a periodically
energized solenoid on each side thereof. As shown in FIGS. 16 and
18 a pair of solenoids SOL-5 are mounted on each side of the
container 300 and are contained in suitable housings 326. Each
solenoid is provided with a weight 327 attached to the armature for
the solenoid and a spring 328 held in compression between the
weight and the solenoid coil for normally biasing the weight
outwardly to the outer extent of movement for the armature. Upon
energization of the solenoids, the respective armature is drawn
inwardly to force its associated weight toward the solenoid coil
against the bias of the spring 328. Upon release of energization of
the solenoid the weight will be driven under action of the spring
to its extreme outer position. As will be described hereinafter, a
control circuit is provided for energizing the solenoids SOL-5
periodically in order to impart quick motion to the weights 327 to
produce a slight hammering upon the toner container 300 thereby
preventing impaction of the toner particles and constantly
maintaining the downward movement of toner for eventual egress
through the nozzle section 302. Normally in the operation of the
toner dispenser, with a supply of toner particles placed within the
container 300, the metering plate 304 and the toner plate 303 form
a control gate for holding back the toner particles from entering
the conveyor tube 225 through the conforming opening 224a. Upon
reciprocation of the gate 304 by the rotation of the drive element
321, a metered quantity of toner particles will be permitted to
pass through the double row of large openings 330 formed in the
gate 304 and to fall upon the stationary plate 303. With toner
particles being built up upon the plate 303, a metered quantity of
toner will steadily cascade over the two longitudinal edges of the
plate from where the toner will fall into the tube 225. Since the
width of the toner plate 303 is greater than the internal width of
the nozzle section 302, the latter prevents the toner particles
from falling directly through the openings 330 and into the tube
225 without first falling upon the plate 303 to be metered thereby.
The toner then actually follows a tortuous path as shown in FIG. 18
by the reference numeral T indicating a typical path of toner
fall.
Since the toner dispenser 15 dispenses a uniform quantity of toner
for a given stroke length of the metering gate 304, it is apparent
that the quantity of toner delivered by the toner dispenser may be
varied by the number of strokes of such movement per unit of time.
Accurate control of the dispensing rate for the toner dispenser can
be accomplished by controlling the time in which the motor M-10 is
energized and the rate of reciprocation of the gate 304, the latter
activity being determined by the gear reduction ratio for the gear
box 323. Assuming that the gear box is adapted to rotate the drive
shaft 322 at approximately 50 r.p.m., it will be seen that the
metering gate 304 will experience relatively few reciprocatory
cycles for any particular time during which the motor M-10 is
energized. It will be apparent with the foregoing arrangement then
that more accurate control is available with the use of a
relatively slow reciprocatory movement of the metering plate 304
since only the motor energization period which can be relatively
broad in view of this slow movement, need be varied to control
toner dispensing.
TONER CONCENTRATION CONTROL
In order to control the dispensing of toner from the toner
dispenser 15, there is shown in FIG. 27-34 the details of an
automatic toner control system which ultimately controls the time
of energization for the dispenser motor M-10 at start up and during
continuous operation of the machine.
Basically, the automatic toner dispensing system comprises a toner
sensor 340 mounted within the developer housing 200 by any suitable
means which electrically grounds the sensor, a flat funnel bin 341
which conveys some of the developer material passing through the
slot 285 in the plate 220 into the sensor 340. As shown in FIG. 27
developer material entering the bin 341, slides downwardly to the
left along the inclined plane 342 of the bin on its way to a bypass
conduit 343. The plane 342 supports an upstanding deflector plate
344 in the path of the downwardly moving material. The conduit 343
is arranged to conduct the flow of the developer material that does
not enter the sensor 340 back into the lower conveyor tube 225 for
continued circulation of the material.
The toner sensor 340 is generally square in shape having a
relatively narrow depth, and resembling a flat box-shaped housing.
It is arranged such that diagonal corners are aligned with the
vertical in order to permit the flow of toner into the upper corner
and to permit egress from the sensor from the diagonally placed
lower corner. Within the sensor housing, there is positioned at the
upper corner of the housing, a triangular shaped baffle element 345
which has the apex of a corner thereof facing upwardly into the
path of the free-falling developer material which flows through a
conduit 346 connected between the upper corner of the housing and
an opening 347 formed in the bin 341. The angled element 345 serves
to split the downwardly flowing developer material into two
separate paths of approximately equal flowing widths. The developer
material flowing along the left path, as viewed in FIG. 27 slides
along one leg 348 of the angled element 345 and along an extension
in the form of an adjustable control gate 349 of the leg until the
development material has its flow obstructed by a guide baffle
plate 350 positioned 90.degree. relative to the path of movement of
the development material and the plane of the gate 349. The lower
end of the control gate 349 is spaced from the guide plate 350 a
narrow distance to permit a controlled amount of the developer
material to change its direction of flow 90.degree., or toward the
lower right corner as viewed in FIG. 32. Excess developer material,
or that material which does not pass between the edge of the gate
349 and the plate 350 flows around the outer end thereof and to an
outlet tube to be described. The developer material now slides in
this direction along the guide plate 350 and onto a conductive
glass plate 351 secured thereon and across which the developer
material flows. A sensing photocell P-1 is secured to the sensor
housing immediately below the plate 351 for a purpose to be
described hereinafter.
Similarly, the element 345 has a second leg which is adapted to
convey development material along another path of movement upon
entering the sensor 340. This leg 352 is also provided with a
projecting extension in the form of a control gate 353 which
directs development material downwardly and to the right and
against a second guide plate 354 positioned 90.degree. to the flow
of the development material in this trunk and relative to the gate
353. As was the case with the guide plate 350, a second conductive
glass plate 355 is insulatingly attached to the plate 354 across
which development material is directed as the material is permitted
to flow through the lower edge of the gate 355 and the adjacent
surface of the plate 354 in a controlled quantity manner. A lamp
LMP-1 is mounted immediately below the plate 355 and arranged so
that when energized, some of the lights rays therefrom will be
transmitted through both NESA plates and impinge upon the photocell
P-1.
The development material which has passed across the plates 351 and
355 and which pass as an overflow across the ends of the guide
plates 350 and 354 are brought together again at the lower corner
of the sensor housing 340 and into an outlet tube 356 which is in
communication with this lower corner. The lower end of the pipe 356
is in communication with opening 224 formed in the lower conveyor
tube 225.
Each of the sensing plates 351 and 355 has a thin transparent layer
of a conductive oxide, preferably formed of "NESA" glass, a
trademark of the Pittsburgh Glass Company, which is generally a tin
oxide coated glass that is transparent to white light. Since both
plates are mirror images of each other, details of only one of the
plates will be described. A pattern 357 is formed on the plate 351
as shown in FIG. 30 and is of L-shape, being produced by scribing
through the oxide layer in order to electrically separate the
pattern 357 from the remaining portion 358. Each of the conductive
portions 357, 358 are connected to a circuit to be described
hereinafter.
In order to accumulate toner in an amount fairly indicative of the
total amount of toner in the developing system, the pattern 357 on
both plates 351 and 355 have applied thereto an electrical
potential of a polarity and amount to attract and retain toner
particles for some predetermined unit of time. During this time,
the light transmission through the accumulated toner on both
patterns 357 will be determined in terms of toner concentration for
the developer material. When the predetermined unit of time has
terminated and after the toner accumulation is sensed, the polarity
on the patterns of the sensing plates is reversed in order to
permit the patterns to repel toner particles thereby effecting the
cleaning of the patterns by means of the developer material allowed
to continue flowing across the patterns brushing toner
therefrom.
As shown in FIG. 31, the conductive portions of each of the plates
351, 355 are connected in parallel and to a timer mechanism
generally indicated by the reference numeral 360, shown in detail
in FIGS. 34 and 35. The timer mechanism 360 is in the form of a
continuously rotating bank of cams which periodically make and
break switches connected to the toner sensor circuit. The timer
comprises a motor M-6 connected to a gear reduction drive mechanism
362 which has its output shaft connected to a shaft 363 rotatably
mounted on a frame 364 for the timer mechanism. The shaft 363 has
mounted thereon for rotation therewith a first cam 365 for
controlling the electrical supply to the timer drive motor M-6
during shutdown of the xerographic machine, a second cam 366 which
controls the time during which the accumulated toner on each of the
plates 351 and 355 is sampled and, a third cam 367 which controls
the polarity upon the plates 351, 355. The cam 365 assures that a
positive polarity is applied to the patterns 357 whenever the
sensor is "cycled out" for a purpose to be described
hereinafter.
The first cam 365 is formed with a control lobe 368 which is
arranged to actuate an actuator 370 for a switch 371 which is
connected to a suitable source of electrical power supply to the
timer motor M-6. This motor is energized whenever a main switch in
the electrical circuit for the machine is closed and the drive for
the horizontal conveyor screws 226 and 247 is activated. During the
shutdown of the machine when it is still processing a last copy and
when the drive to the conveyor screws 226, 247 has terminated, the
switch 371 will maintain the motor M-6 energized for a complete
sensing cycle which, as will be further described, lasts about 6
seconds. The developer material used in this last cycle is
furnished from the conduit 346 which serves as a sump for this
purpose. Closing of the switch 371 assures shutdown of the motor
M-6 only when the regions 357 have a positive polarity or that
polarity opposite that of the toner particles utilized.
Before proceeding further in the description of the timer circuit a
brief description of the sensing and nonsensing mode of operation
for the toner sensor 340 will be described in relation to the timer
360 and the electrical power thereto.
The circuit for the toner sensor and the components thereto are
arranged and programmed so that sensing of toner concentration
occurs periodically and asymmetrically, that is, for a short,
predetermined time interval, or, after a relatively long
predetermined time period. For purposes of illustration of these
time periods and controls, the sensor control circuit is adapted to
"sample" or sense the toner concentration accumulated upon the
patterns 357 for a period of one-tenth of a second, which period
occurs after the patterns are in the "attract" mode for about
four-tenths of a second prior to sampling. During the "attract"
mode which encompasses the "sampling" period, the patterns 357 are
of positive polarity or that polarity opposite the polarity on the
toner particles. After approximately one-tenth of a second for the
"sampling" period, the electrical power for this sensing function
will be terminated until the next cycle. The cycle of placing the
sensor in the "attract" condition, sampling, and cleaning the
sensor occurs every 6 seconds when the xerographic machine is in
the continuous print mode of operation. In the illustrated example
with the "attract" mode lasting approximately five-tenths of a
second and the "clean" cycle 51/2 seconds, the toner density
sensing is asymmetrical in its cycling.
As shown in FIG. 34 there is illustrated a series of time graphs
for a 6 second cycle of toner concentration sampling and control.
During this 6 seconds, the output shaft 363 for rotating each of
the cams 365, 366 and 367 makes one complete revolution. As
previously stated, the switch 371 is actuated by the cam lobe 368
on the cam 365 and comes into service only for the last 6 second
sensing cycle during processing of the last copy of a particular
production run. The circular length of the lobe 368 is such as to
maintain closing of the circuit to the timer motor M-6 for nearly
the entire 6 second period and as shown in FIG. 34 the switch 371
is actuated to a closed position until approximately 5.85 seconds
has transpired or when the cam reaches the line 372 on the curve A.
During use of the machine before the last copy is being processed,
the switch 371 is bypassed. It is, in effect, an auxiliary AC path
to assure shutdown in the "attract" mode. At the end of the 6
second period the switch 371 is again actuated to a closed
condition commencing the next cycle of the sensor control.
As shown by the time curve B, just prior to reaching the line 372,
the cam 367 which actuates a normally closed switch 373 to an open
position and a normally open switch 374 to a closed position causes
these switches to be actuated such that the normally open switch
373 closes to cause the patterns 357 to be supplied with positive
potential from the power supply 375, thereby holding the patterns
in the "attract" mode. This "attract" mode will remain until the
termination of the 6 second cycling period. This is illustrated in
the timing curve B by the line 376. Simultaneous with this
actuation of the switch 373 is the actuation of the normally closed
switch 374 which when open prevents the flow of negative potential
to the areas 358 of each of the sensor plates 351, 355. This
occurrence is illustrated in time curve C by the line 377.
After the plates 351, 355 have been placed in the "attract" mode
for approximately four-tenths of a second, the cam 366 actuates a
switch 378 which controls activation of a control circuit in a
threshold detector 369 for conditioning the photocell P-1 to vary
its resistance in accordance with the intensity of the light rays
from the continually energized lamp LMP-1. This "sample" period
remains for approximately one-tenth of a second, starting from the
sampling "ON" time when the photocell P-1 is energized, illustrated
by the line 380 in time curve D. As shown in FIG. 33, the control
end of the lobe 368 for the cam 365 is spaced angularly from the
control end of the lobe 381 for the cam 366 and also spaced from
the control end of the lobe 382 for the cam 367. The angular
relationship between the lobes 382 and 381 is such as to permit the
elapsed time between the beginning of the "attract" mode and the
instant that the photocell P-1 is energized. The angular distance
between the lobes 382 and 368 is such that the patterns 357 are
energized to a positive potential before the motor M-6 is
de-energized in the processing of a last copy.
For illustrative purposes, the polarity indicated in FIG. 30 and 31
in relation to the sensing plates 351, 355 are those polarities of
the supply voltage when the plates are in the "attract" mode. For
this convention then, it was assumed that the charge upon toner
particles is negative and, therefore, would be attracted to the
control patterns 357 for each of the sensing plates. It is also
assumed that the other conductive areas 358 are being supplied with
negative DC potential. This electrical configuration is merely
illustrative and has been chosen for descriptive purposes because
of the particular charge chosen for the toner particles which, as
previously stated, is negative. The positioning then of the
actuator arms for the switches 373 and 374 is such that toner
particles will be attracted to the patterns 357 and repelled from
the patterns 358.
As previously stated, in order to exhibit high sensitivity and
rapid response time, the electrical circuit shown in FIG. 31 is
adapted for periodic sensing action, for every 6 second period
during which the reproduction machine is in continuous operation.
During the "attract" mode, the toner will accumulate upon the
patterns 357 and, in an amount indicative of the amount of toner in
the developer material. When the timer 360 has effected switching
of the switches 373, 374 the polarity of the patterns 357 and the
portions 358 are reversed where upon the patterns 357 assumed a
negative polarity and the portions 358 a positive potential. In
this manner, the control patterns 357 will repel the toner
cascading down the inclined plates 351 and 355 during this portion
of the control cycle. When the polarity is thus reversed, the
patterns 357 are cleaned by the cascading developer material and
thereby is preconditioned during this "clean" cycle for another
"attract" cycle.
In order to determine the extend of toner concentration that has
accumulated on both control patterns 357, the toner sensor 340 is
provided with the photocell lamp combination P-1 and LMP-1. As
previously stated, the photocell is positioned adjacent the lower
surface of the plate 351 so that toner particles cascading through
the toner sensor and accumulating upon both regions 357 will
intercept light rays from the lamp LMP-1 positioned behind the
lower surface of the other plate 355. The photocell P-1 in effect
will "see" light rays which traverses the cascading developer
stream flowing upon both plates 351, 355 and, the accumulated toner
particles on each of the patterns 357.
Electrically the photocell P-1 is connected to the threshold
detector 379 in form of a Schmitt trigger which is adapted to
produce a pulse when the resistance in the photocell attains a
predetermined value indicative of the intensity of the light rays
that reach the photocell from the lamp LMP-1 during the "sample"
cycle. The detector 379 derives its power from a power supply 386
which also supplies the lamp LMP-1 with its electrical energy.
The pulse generated from the Schmitt trigger 379 is fed to a
machine logic circuit 387 which, when combined with other necessary
signals from the reproduction machine, is fed to a timer relay 388
by way of an amplifier 390 and then to the toner dispenser motor
M-10 connected in series with the relay contact for the relay 388.
The timer relay 388 is arranged to remain "ON" for any adjustable
predetermined timed period for each pulse thereto from the
threshold detector 379. For each pulse fed to the timer relay, the
motor M-10 will remain energized until the timer period, which may
be in the range from 1-10 seconds, has terminated whereupon the
motor M.varies.10 will become de-energized for that pulse. As
previously stated during energization of the motor M-10 the
metering gate 304 is cyclically moved by means of the carriage
305.
During normal operation of the automatic toner dispensing
apparatus, the light source LMP-1 is continuously energized for
presenting light for both plates 351 and 355 arranged optically in
series. The light rays which traverse both of these plates impinges
upon the photocell P-1 which is compared with predetermined values
in the Schmitt Trigger 379. In the event that the predetermined
value is not exceeded during the sampling step wherein the
photocell is energized, the excess is utilized to produce a pulse
which is fed to the logic 387 as an indication that the toner
concentration in the development material is below a desired
level.
As the density of the toner that cascades over the sensing plates
351, 355 increases, the signal on the photocell P-1 will be in
balance with the predetermined value in the Schmitt trigger 379
thereby terminating periodic energization of the motor M-10.
It will be appreciated that with the presence of both sensing
plates 351 and 355, the sensitivity of the sensing circuit is
relatively high since there is a much wider range of variation that
light rays may experience in reaching the photocell P-1. This also
results in the control of a relatively wide density range that the
xerographic reproductions may attain, or in other words, the
density that the toner concentration maintains can be closely
regulated. With this narrow range of variations and with the
continuous short sampling time per unit of time, the xerographic
machine is capable of experiencing a relatively narrow, high
quality contrast control since the slightest unbalance will demand
toner and produce replenishment thereof.
The toner dispenser 15 functions to sift toner material into the
development material in the conveyor tube 225 in order to insure
maximum mixture of the fresh toner with the material already in the
development process. The metering gate 304 and the toner plate 303,
upon which toner particles fall, are of sufficient length as to
span a relatively long length of the conveyor 226. The continual
motion of the screw conveyor 226 brings the newly mixed development
material into position to be carried upwardly by the vertical
conveyor belt 236.
SHEET FEED MECHANISM
The sheet feeding mechanism 18 illustrated in FIGS. 35-41 is
positioned for the seriatim feeding of cut sheet transfer material
into contact with the xerographic belt 12 so that developed powder
images on the surface of the belt may be transferred to the
transfer material. The mechanism includes a tray for holding a
supply of cut sheet transfer material, separator rollers and
devices for separating a single sheet of transfer material from the
top of the stack of transfer material on the tray, feed rollers for
feeding a single sheet into the transport system 16 in order to
bring the sheet into impression contact with the belt 12 and means
for coordinating the operation of the separator rollers and feed
rollers to thereby feed a single sheet of transfer material into
contact with the belt 12 at proper registration of the powder image
on the belt onto the transfer material. A paper tray level control
device is also provided for raising the tray as sheets of paper are
fed from the top of the paper supply.
Referring now specifically to the drawings, the apparatus for
feeding sheets of transfer material to the transport system 16 in
timed relation to the appearance of a developed image on the belt
12 includes a paper tray 400 slidably positionable from the side of
the machine between frame plates 401, 402 and arranged to hold a
stack S of various widths of sheet material such as paper.
The paper tray 400 includes a paper stack supporting base
comprising two sections: a stationary base section 403, and a
movable base plate 404, both plates being coplanar and including
flat relatively wide fingers 405 (see FIG. 38) which intermesh when
both plates are joined to support a stack of paper. The fingers 405
support the stack when the rearwardly extending movable base plate
404 is pulled rearwardly to the position shown in dotted lines in
FIG. 39 and indicated by the numeral 406. The base plate may be
placed in this position when loading the paper tray with long
(legal size) paper which requires the machine to run in a long
pitch mode.
The stationary plate 403 is held against movement within its plane
by means of box-like structure 407 having one edge 408 welded to an
intermediate plate 409 which in turn is spot welded to the bottom
surface of the stationary plate 403. The sides of the intermediate
plate 409, which extends in a plane parallel to and below the
combined plane for the plate 403, 404 are formed into downwardly
projecting tapered side panels 411 which are held against forward
or rearward movement by a slide mechanism to be described
hereinafter. The intermediate plate 409 is formed with a slot 412
arranged centrally between the side panels 411 and extending for
nearly the entire length of the plate 409. Through this slot
extends a pair of screws 413 secured to the bottom surface of the
central finger 405 of the movable base plate 404. These screws
serve to support a ribbon 414 positioned parallel to and below the
plate 404 and is formed with a depending portion 415 which is
adapted to engage an actuator 416 of a switch SW when the movable
plate 404 is pulled rearwardly. The switch SW may be connected as
an interlock circuit to effect change in machine pitch resulting
from the use of longer sheets of transfer material. In loading the
paper tray with longer sheets, the plate 404 is extended not only
to accommodate longer sheets but also to condition the machine for
the long pitch mode.
Each of the side panels 411 is adapted to be driven vertically in
order to cause raising and lowering of the paper tray during paper
feed operation. To this end, the base plate 401 has secured thereto
a channel member 420 having its open side extending inwardly and
arranged in a vertical position. Similarly the base plate 402 is
provided with a channel member 421 secured thereon to face the
channel 420. The channel member 420 is adapted to receive a pair of
guide rollers 422 mounted in space relation upon a vertically
extending plate 423 secured in a vertical arrangement upon one of
the side panels 411. In like manner, the channel 421 serves to
guide vertically a pair of vertically spaced rollers 424 mounted
upon a plate 425 secured to the other side panel 411. With this
arrangement, the paper tray is free to move vertically and is held
against horizontal movement by the confinement of the side panels
411 to the fixed channels 420, 421.
In order to produce control and automatic movement of the paper
tray vertically, the forward edges of each of the plates 423, 425
is provided with a gear rack 426, 427 respectively. A train of
three vertically aligned gears are adapted to drive each of the
gear racks in order to impart vertical motion of the paper tray. As
shown in FIG. 39, the gear rack 427 is in direct mesh with an upper
gear wheel 428 mounted for rotation upon a stud shaft 430 secured
to the frame plate 402. Mounted below the gear 428 upon a stud
shaft 431 is an intermediate gear 432. Below the intermediate gear
432 is a third lower gear 433 secured to a drive shaft 434 having
one end secured to the frame plate 402 and its other end mounted
for rotation on the frame plate 401.
This completes the three gear train for the side of the paper
feeder frame which supports the gear rack 427. On the other side of
the paper frame is a second gear train comprising gears 435, 436
and 437 arranged on stud shafts 438, 439 respectively for the gears
435 and 436 and the drive shaft 434 to which the lower-most gear
437 is secured. It will be apparent that the shaft 430 and 438 are
in actual alignment as are the shafts 431 and 439. It will also be
apparent that upon rotation of the lower-most gears, 433 and 437,
motion will be imparted to each of the respective upper gears which
in turn produce corresponding movement of the respective gear racks
426, 427.
In order to produce rotation of the lower-most gears, the outer
extremity of the drive shaft 434 on that side of the sheet feed
mechanism having the base plate 401, has secured thereto a drive
gear 440 which is in mesh with a worm gear 441 formed on a shaft
442 mounted for rotation between flanges of a bracket 443 which
also supports a paper elevation motor M-2 having its shaft
connected to the shaft 442 for imparting rotation thereto.
Preferably the motor M-2 is adapted to produce low r.p.m. rotation
which when coupled with the worm gear 441 and drive gear 440 impart
relatively slow motion to the paper tray.
Centering of the stack S of paper relative to the optical
centerline of the copier/duplicator machine in order to insure
proper registration and feeding of individual sheets of paper from
the top of the stack is accomplished by a pair of vertically
extending guide members 445, 446 arranged at the forward corners of
the stack when in position for separation operation. The guide
member 445 is supported in an upright position by means of a
horizontally extending guidepin 447 suitably secured to the frame
plate 401 and extending through a boss 448 formed in the guide
member 445. Similarly the member 446 is supported in a vertical
position by a guide pin 450 secured to the frame plate 402 and
slidably received in a boss 451 formed in the upright. The guide
members 445 and 446 are also formed at the lower ends with bosses
452 and 453 respectively which extend inwardly toward one another
and in axial alignment. As shown in FIG. 40, the drive shaft 434 is
positioned within the bosses 452, 453 for supporting the guide
members 445, 446 and to permit movement of these guide members
toward and away from each other.
As shown in FIGS. 39 and 41 the guide member 445 is formed with a
guide edge 454 that extends vertically along the length of the
guide member and adapted to engage the leading edge of the stack of
paper at one corner thereof. Engaging the side edges of the stack S
along the same corner is a guiding surface 455 also formed along
the length of the member 454. The guide member 446 is similarly
formed with a front guide edge 456 and a side guide edge 457 for
guiding the leading and side edges of the stack of paper at that
corner. The side edges 455 and 457 are adapted to be moved toward
and away from each other and relative to the center line of the
paper tray 400 in order to center the stack S relative to the
optical axis of the xerographic machine as the axis will manifest
itself during the image transfer step.
In order to drive the side edges 455, 457 toward and away from each
other, the paper feeder 18 is provided with a manually operable
centering drive system comprising a pair of links 460, 461 each
having an end connected to one of the bosses 452, 453 and the other
end connected to a block 462 mounted for rotation upon a shaft 463.
The points of connection of the links 460, 461 with the block 462
are offset relative to the axis of rotation for the block in order
to cause movement of the bosses 452, 453 upon rotation of the block
462 in either direction. Rotation of the shaft 463 is accomplished
by a knob 464 secured at the outer end of the shaft 463 at the rear
of the paper handling mechanism 18. A lock knob 465 secured to the
extremity of the shaft 463 serves to move the knob 464 axially
relative to the shaft and against a non-rotatable block 466 mounted
on a spacer block 469 and held axially thereto by a suitable
shoulder 467 formed on the shaft. Rotation of the knob 465 will
lock the knob 464 against rotation in order to prevent inadvertent
driving movement being imparted to the guide members 445, 446. It
will be apparent that upon rotation of the knob 464, the block 462
will be rotated for driving the links 460, 461 in either direction
in order to impart corresponding movement of the bosses 452, 453
respectively. During a paper loading operation, the knob 464 is
rotated to space the members 445, 446 apart to accommodate various
widths of transfer material on the tray 400 and to permit the easy
loading of additional sheets upon the tray. After the tray has been
supplied with sheets the knob 464 is rotated to drive the guide
members toward each other in unison thereby aligning the stack
relative to the optical center line of the xerographic machine in
proper position for paper feeding.
The driving action produced by the knob 464 and the shaft 463 in
order to separate the members 445, 446 is against the bias of a
spring 468 held in tension by being connected at its ends to each
of the guide members and normally biasing them toward one another.
Preferably, the spring is of such a strength that with the knob 464
left unsecured the guide members will be normally forced inwardly
against the adjacent side edges of the stack of papers thereby
enhancing good side-to-edge alignment.
The coacting side guide edges 455, 457 coacting with guide follower
elements 470 secured on the outwardly extending ends of a pair of
rods 471, 472 held in axial alignment and being slidably mounted
within blocks 473, 474 respectively, secured below and in spaced
relation to the stationary plate 403 of the paper tray support the
corners of the stack of transfer material. A rod 475 is slidably
retained in the opposing ends of the rods 471, 472 and has a spring
476 encircling it in order to maintain the rods 471, 472 outwardly
to force the follower elements 470 against the guide members 445,
446. The guide elements 470 fill the corner gaps and support paper
of all widths.
Generally, the upper ends of the guide edges 454, 456 are held at a
point slightly below the top sheet of the stack S. As individual
sheets of paper are fed from the stack, each is adapted to slide or
to be driven over the top ends of the members. Means are provided
for separating only the top sheet from the stack during a paper
feed operation. In order to insure separation of the topmost sheet
only from the stack, there is provided at opposite corners of the
stack, separating devices which apply a light restraining force on
the forward corners of the topmost sheet and the leading edge of
the paper stack. Each of the separating devices comprise a
vertically movable plunger 476, 477 freely movable in a vertical
passageway 478 formed in each of the forward portions of the guide
members 445, 446. Each of the plungers has a snubber 480, 481
secured thereto at a plane slightly above the upper ends of the
plungers and to be movable therewith.
The weight of each of the plungers 476, 477 is imposed on the upper
forward corners of the paper stack. Normally the weight on each
corner is such that the plungers will follow the level of the stack
downwardly as the stack level is lowered by continuous feeding of
paper. Their weights also provide a restraining force which will
assist in the feeding of a single sheet of paper when the stack is
acted upon by separator rollers to be described hereinafter. It is
preferred that the limits of downward movement for the plungers
474, 476 are short in order to limit the downward movement of the
corresponding snubbers. This is to limit the lowering of the
snubbers when the level of the stack is lowered prior to a tray
loading procedure and to guarantee that the snubbers are atop the
corners of a freshly loaded stock without manual manipulation
thereof. As it is raised assuming proper centering by the guide
members 445, 446 the adjacent corners of the stack will engage the
snubbers and carry them upwardly until the top of the stack is at
its proper predetermined position for feeding of the top sheet.
To feed sheets of paper one at a time from the stack S and into the
narrow slot formed between two closely spaced guide chutes 482, 483
arranged just forward of the top few sheets of the stack S, there
is provided a paper separating means comprising a first pair of
intermittently driven rollers 485 mounted for rotation adjacent the
side edges of the stack and a second pair of driven rollers 486
mounted inwardly of the rollers 485. All of the rollers are
engageable with the top of the paper stack. Each of the outboard
rollers 485 is mounted for rotation on and by a driven shaft 487
associated with each of the rollers by means of a one way clutch
488 which permits each roller 485 to rotate freely in that
direction that the topmost sheet moves when it is pulled out from
the stack at a greater rate than the roller is capable of moving
the sheet.
The inboard rollers 486 are mounted for rotation upon a drive
sleeve 490 which is drivingly connected to each roller by means of
a one way roller clutch 491 similar to the clutch 488. The shafts
487 are mounted each within an end of the drive sleeve 490 which
also contains within its interior a coil spring 492 which serves to
force the two shafts 487 outwardly for positioning the outboard
rollers 485 to a predetermined position relative to the edge of the
stack. This outward movement is limited by suitable buttons 493
which engage the edge guides 455, 457. As the guide members 445 and
446 are moved outwardly the shafts 487 will follow the same in
order to insure that the rollers 485 maintain their set relation to
the edges of the stack regardless of stack width.
Rotation is imparted to each of the shafts 487 by a pin 494
connected between each shaft and the end of the drive sleeve 490.
The sleeve shaft 490 at each end is formed with a slot into which
each pin is adapted to be inserted for connecting the shaft and for
permitting limited axial movement of each outer roller 485.
Driving rotation is imparted to the drive sleeve 490 by way of a
timing pulley 495 secured axially of and at the center of the
sleeve and held between the flanges of a channel support arm 496
which supports the sleeve 490 and the rollers 485, 486. The channel
arm 496 is formed in two parts: a forward part 497 the end of which
supports the sleeve 490 as previously stated and a supporting
section 498 which conforms with the shape and direction of the
portion 497. These sections are connected in end-to-end relation by
means of an opposing slot 500 formed in the portion 498 and
co-acting tongue 501 on the section 497 loosely insertable in the
slot 500 to permit disconnection of the parts 497, 498. The loose
connection between the slot 500 and tongue 501 also permit limited
rotation of the portion 497 about its longitudinal axis in order to
allow all four rollers to contact the material surface regardless
of stack deformation due to humidity.
The portions 497, 498 are detachably held one to another by means
of an adjusting screw 502 positioned within the channel shape of
the arm 496 and which is threadedly received at one end in a tapped
portion 503 formed in the section 498 and at its other end that it
received in a boss 504 formed in the portion 497. A suitable
retaining ring is employed relative to the boss 504 for permitting
rotary action of the screw 502 but preventing axial motion relative
to the boss. The screw 502 serves as adjsutment means between the
portions 497 and 498 to control tension on the timing belt utilized
to rotate the rollers 485, 486.
The support arm 496 is secured between the frame plates 401, 402 by
means of a sleeve 505 which is mounted at one end through a knurled
thimble 506 which is rotatably adjustable and supported upon a
support sleeve 507 secured by suitable screws to the frame plate
401. Normally the arm 496 is under the influence of gravity in a
direction to maintain the two pairs of rollers 485, 486 into
engagement with the topmost sheets of the paper stack. However,
additional force must be added in order to increase the force of
the rollers upon the stack. This is accomplished by means of a
torsion spring 508 having one end secured to the thimble 506 and
its other end connected to a retaining plate 509 through which the
sleeve 505 extends and is secured. The spring 508 may be adjusted
in tension between its two supporting structures in such a manner
as to impart rotation to the support sleeve 505 in addition to that
rotation produced by gravity for more reliable feeding of heavier
weight transfer material. When the stack is removed, the retaining
plate 509 also serves to limit the downward movement or rotation of
the arm 496 and prevent the undue stress on the structural parts.
The retaining plate 509 also serves to actuate the "up" elevator
switch SW-3 and the "down" elevator switch SW-4 in a manner to be
described hereinafter.
Held within the support sleeve 505 and extending across almost the
distance between the plates 401, 402 is a drive sleeve 510 mounted
for rotation at one end by a bearing 511 having its outer race
secured to the inner recess of the support sleeve 507 and, a clutch
mechanism 512 supported by suitable screws upon the frame plate
402. Axially rotatable within the drive sleeve 510 is a drive shaft
513 supported at one end in a bearing 514 mounted within the
support sleeve 507 and, at the other end extending beyond the frame
plate 402 and terminating in a drive pulley 515 associated with a
drive system to be described hereinafter. The clutch is adapted,
when energized, to operatively connect the drive shaft 513 with the
driven sleeve 510 in order to produce rotation of a timing pulley
516 positioned between the flanges of the arm 496 and which is
associated with a timing belt 517 also wrapped around the timing
pulley 495 in order to impart rotation thereto. During operation
when the clutch 512 is energized rotative motion is imparted to the
pulley 516 which correspondingly imparts rotation to the timing
pulley 495 for rotating the inboard paper feed rollers 486 and
consequently the outboard rollers 485.
In operation, as the topmost sheet is frictionally advanced by the
rollers 485, 486, the leading edge corners of the sheet engage the
snubbers 480, 481 which are formed so as to present a continuation
of the vertical front guide edges 454, 456 and hence a vertical
barrier to the passage of sheets, but one limited to the outer
extremes of the leading edge of the forward moving topmost sheet.
As the rollers 485, 486 apply a forward force to the topmost sheet,
the two forward corners of the sheet thus restricted by the
snubbers, create a lag in the forward movement of the corners as
the sheet is continually advanced. This lag will produce slight
inward sliding movement of the corners of the sheet of paper with
consequent buckling of the sheet. This buckling action of the
topmost sheet insures its separation from the underlying sheets in
the stack.
During feeding of the topmost sheet into the space between the
guide baffles 482, 483, both pairs of feed rollers 485, 486 are
positively driven to affect this movement. As the sheet advances,
its leading edge moves into the gate of the slightly separated
registration rollers 520, 521 which eventually engage the sheet and
pulls the same their remaining distance in order to clear the stack
S. This second movement of the sheet is slightly faster than the
initial driving action produced by the feed rollers 485, 486 and
thereby results in the feed rollers rotated individually and freely
in view of the individual one-way clutches associated with each of
the rollers. Actually at this point, when the registration rollers
502, 521 take over control of the feeding of the sheet,
energization of the clutch 512 is terminated thereby stopping the
positive drive action by the drive sleeve 490. In the event the
topmost sheet becomes slightly askew as it is advanced across the
remaining portion of the paper stack, perpetuation of this unwanted
skew condition is prevented in view of the fact that the feed
rollers 485 and 486 will stop individually and sequentially as the
topmost sheet trailing edge is pulled from under them. Without
individual one-way clutches, the next sheet in the stack will skew
as each successive roller drops off the trailing edge of the
previous sheet being skewed. Since these rollers would be secured
to a common shaft, none can stop turning until all have cleared the
trailing edge. Rollers still on a skewed top sheet will continue to
drive those rollers that have cleared the trailing edge, thereby
urging that portion of the next sheet forward, perpetuating the
skew.
The paper tray 400 is limited in its downward movement by means of
a limit switch SW-7 mounted upon the frame plate 401 and
electrically connected to the paper elevation motor M-2 through a
logic circuit for de-energizing M-2 upon activation of the switch
when the tray reaches a predetermined low position. This is
accomplished by means of a projection 522 secured to the plate 425
and which actuates the switch SW-7 at the predetermined low point.
Another switch SW-8 mounted on the frame plate 401 controls the
upper limit of travel of the paper tray 400 by means of a
projection 523 mounted on the plate 425. In the event the tray 400
attains a predetermined high point, the switch SW-8 is actuated
through the logic circuit in order to terminate energization of the
paper elevation motor M-2. The relationship between the switches
SW-3, SW-4, SW-7 and SW-8 in conjunction with manually operable
switches for the motor M-2 will be described in description of the
electrical circuit.
SHEET REGISTRATION MECHANISM
In the sheet registration mechanism illustrated in FIGS. 39, 42-29
the registration rollers 520, 521 are adapted to cooperate with a
pair of registering fingers interposed in the path of movement of a
sheet being fed by the separator rollers 485, 486 in order to align
the leading edge of each sheet to a precise position before the
sheet is permitted to continue on to the paper transport mechanism
16 whereat the developed electrostatic image on the belt 12 will be
transferred. As shown in in FIG. 43, the upper registration roll
520 comprises a central metallic core 525 having a plurality of
soft rubber layers 526 therearound adapted to engage frictionally a
sheet of paper. The roller 520 is mounted at one end on a stub
shaft 527 (see FIG. 47) supported in a bearing housing 528 held by
a clamp 530 to the shaft and, at its other end on a stub shaft 531
supported in a bearing housing 532 held thereto by a clamp 533.
At the left end of the registration roller 520 as viewed in FIG. 42
a sprocket 534 is secured to the stub shaft 531. The bearing
housings 528 and 532 are eccentric in nature so as to provide
adjustment to the pinch between the upper register roller 520 and
the lower roller 521. The ends of the registration roller 520 is
also supported by levers 535, 536 (see FIG. 36) pivotally mounted
at their ends by fixed stub shafts 537 secured on the frame plates
401, 402, respectively, in axial alignment. The stub shaft 537 that
is fixed to the plate 402 also has secured thereto a sprocket 538
which is arranged in driving connection with the sprocket 534 by a
drive chain 540 for driving the registration rollers to be
described hereinafter. A suitable idler sprocket 541 is also
mounted on the lever 536 and operatively associated with the chain
540 to permit tightening of the chain 540 or removal thereof from
the operating sprockets.
The top edge of the frame plate 401 is formed with a generally
vertically extending slot 542 into which the stub shaft 527 for the
upper roller 520 is adapted to be placed when this roller is in
operating position. Similarly, the shaft 531 at the other end of
the roller is adapted to be positioned within the open ended slot
543 formed in the upper edge of the frame plate 402. The provision
of the slots permits the pivoting movement of the driven roller 520
out away from the lower idler roller 521 and of the path of
movement of the paper and, in fact, away from the cooperating
structure therefor to permit maintenance and paper jam
clearing.
Located immediately below the top registration roller 520 and
parallel therewith, the lower roller 521 comprises a plurality of
free-wheeling, short rollers 544 all of which are rotatably mounted
with ball bearings upon a common sleeve 545 which is rotatably
mounted on a shaft 546 by means of a roller bearing 547 provided at
each end thereof. The shaft 546 is mounted at one end to the frame
plate 401 by suitable bearings and at the other end by a bearing
548 secured in a solenoid mount 549. At this end, the shaft 546
terminates in a straight slot 550 into which projects a tongue 551
formed on the end of a movable actuator 553 for a double-acting
rotary solenoid 554 the details of which will be described
hereinafter. The solenoid 554 comprises an "up" solenoid SOL-1 and
a "down" solenoid SOL-2 and is adapted to impart non-axial rotary
motion to the drive shaft 546 in either direction for approximately
45.degree. upon energization of each of the solenoid coils
associated with the solenoids SOL-1 and SOL-2.
Mounted upon the sleeve 545 between any two of the free wheeling
rollers 544 are registration fingers 555 which are secured by
suitable set screws upon the sleeve 545 to be moved therewith or
held stationary when the sleeve is held against rotation.
As shown in FIG. 48, the periphery of the roller 520 is slightly
spaced from the periphery of the rollers 544. This spacing is
greater than the thickness of a sheet of paper and permits the
sheet to enter within the nip between the rollers and, against the
fingers 555 and to maintain this position until a feed cycle is
activated. At this time in the cycle, paper is still being driven
by the feed rollers 485, 486. This action is opposed by the fingers
555 in the paper path causing the paper to buckle momentarily,
squaring the front edge. With the forward edge of a sheet of paper
against the fingers 555, the upper roller 520 is continuously
driven but being spaced slightly from the top surface of the sheet
of paper it is incapable of driving the sheet beyond the fingers
555. In order to permit the proper alignment of the forward edge of
the sheet of paper against the registration fingers 555 and then to
accomplish forward feeding movement to the sheet by means of the
rollers 521, 520, the registration system is provided with a
control mechanism which controls the movement of the upper roller
520 downwardly into engagement with the sheet of paper located
therebelow in order to drive the same at the same time as the
retracting movement of the fingers 555 in order to eliminate the
impeding action by these fingers against the forward edge of the
sheet.
This control mechanism includes a first link member 556 arranged to
encircle both shafts 531, 546 for the rollers 520, 521 respectively
adjacent the frame plate 402, and, a second link member 557
arranged to encircle both shafts for the upper and lower
registration rollers adjacent the frame plate 401. These link
members more or less hold the two rollers in superimposed close
relationship. Movement of the upper registration roller 520 toward
the lower roller a slight increment is accomplished during
energization of the solenoid SOL-2. Upon this energization, the
actuator 553 is rotated an angular distance of 45.degree. which
action imparts similar rotation to the drive shaft 546. As shown in
FIG. 50, a crank 558 secured to the shaft 546 of the lower roller
521 and having a cam pin 559 arranged for movement in a cooperating
arcuate internal cam 560 formed in the lower end of the link 556 is
adapted to force the shaft 531 toward the shaft 546. As previously
stated, the levers 535 and 536 permit limited movement of the upper
roller 520 toward and away from the lower roller 521. As the crank
558 is rotated clockwise as viewed in FIG. 49 the cam pin 559, as
it moves from the right hand end of the cam 560 to approximately
the center point thereof, will drive the link member 556 slightly
downwardly carrying therewith the roller 520 toward the roller
521.
In order to maintain the fixed position of the shaft 546 for the
lower roller, the link 556 is formed with a vertical extending slot
561 through which the shaft 546 extends. This provides a lost
motion connection between the link 556 and the shaft 546 during the
slight upper and lower movement of this link. Continuing movement
of the cam pin 559 from the approximate center point of the cam 560
to the left hand end of the cam, a total angular distance equal to
45.degree. produced by the continued rotation of the solenoid SOL-2
armature 553, the distance between the axes of the shafts 531 and
546 remains the same. This movement of the cam pin 559 can be
considered dwell time for the operation of the motion producing
mechanism to effect engagement of the rollers 520, 521 in order to
permit the remaining rotation of the shaft 546 to perform another
function, that of rotating the registration fingers 555 out of
engagement with the leading edge of a sheet of paper positioned in
the paper guides 482, 483.
The mechanism to control movement of the fingers 555 is illustrated
in two sequences of operation in FIGS. 46 and 47 and is effected by
actuation of the link member 557. The link member 557 is identical
with the link member 556 and is formed with a vertical straight
slot 562 through which the shaft 546 extends for lost motion when
the link member 557 is moved and , an internal cam 563 through
which a control cam pin 564 projects. The curvature and angular
relationship and distance of the cam 563 relative to the axis of
the shaft 546 is the same as the cam 560. Consequently during
rotation of the shaft 546 in a clockwise direction, as viewed in
FIG. 49, the positioning and movement of the pin 564 is the same as
the pin 559.
Secured to the shaft 546 adjacent the link member 557 is a sector
gear 565 to which the cam pin 564 is attached. Meshing with the
gear 565 is a second sector gear 566 mounted for rotation on a
pivot pin 567 secured to the frame plate 401. The pivot pin 567
also supports for rotation thereon a cam member 568 secured to the
sector gear 466 and made adjustable therewith by means of a set
screw 569 threadedly received in the member 568 and engageable with
the sector 566 to permit angular adjustment of one with the other.
It will be apparent upon rotation of the shaft 546, the sector 565
will be rotated and the cam pin 564 will be moved in the cam 563
thereby driving the link member 557 downwardly. This motion of the
link member 557 is simultaneous and equal to the motion of the
downward link 556 in order to impart the smooth uniform motion of
the roller 520 downwardly.
As shown in FIG. 47 the cam member 568 is formed with an angled
internal cam which is formed so as to have a first cam portion 570
with a center of curvature approximately coincident with the axis
of the pivot pin 567 and a second cam portion 571 which merges with
one end of the angled cam but extends radially toward the pivot pin
axis. The angled cam is adapted to control movement of a rotatable
actuating element 572 rotatably mounted on the shaft 546 adjacent
the sector gear 565 and secured to one end of the sleeve 545. This
is accomplished by means of a control pin 573 secured to one end of
the actuating element 572 and retained within the cam portions 570,
571 to be movable therein. Upon rotation of the member 568 from the
position shown in FIG. 47 wherein the pin 573 is in the arcuate cam
portion 570 of the angled cam, no rotation is imparted to the
actuating member 572 that is, the register fingers 555 will not be
rotated. This result occurs because the control pin 573 merely
slides in an arcuate cam as the cam member 568 pivots about its
axis. This initial rotation of the member 568 is produced by the
initial energization of the solenoid armature SOL-2 which action
also produces the short movement of a control pin 559 for the first
portion of its movement in the cam 560 as previously described. The
resultant action merely keeps the upper roller 520 against the
lower roller 521 and the register fingers in dwell.
When the pin 573 reaches the end of the cam 570 at the apex of the
cam angle, continued rotation of the link member will actuate the
pin 573 in the same direction therewith to produce clockwise
rotation of the actuating element 572 as viewed in FIG. 47 in order
to produce slight rotation of the sleeve 545 along its axis. Since
the fingers 555 are secured to the sleeve 545 this last motion of
the rotation of the link members 557 causes movement of the fingers
away from the leading edge of the sheet of paper between the
rollers 520, 521. This rotation of the fingers will be clockwise as
viewed in FIG. 48. The set screw 569 is utilized to orientate the
member 568 relative to the sector gear 566 in order to insure
proper rotation of the actuating member 572 at a time when the
rollers 520, 521 are in engagement. When this occurs the upper
roller 520 engages the short rollers 544 of the lower roller to
impart rotation thereto for driving this sheet therebetween at the
same time that the fingers 555 are moving in the same direction as
the leading edge of the sheet but in additional downwardly motion
in order to become clear of this edge.
From the foregoing the paper sheet feeding mechanism 18 is adapted
to feed continuously individual sheets of paper to the sheet
registration device in the form of the rollers 520, 521 and the
fingers 555 located in the path of movement of the paper. The sheet
registration device arrests and aligns each individual sheet of
material and then in timed relation to the movement of the
xerographic belt 12 advances the sheet material into contact with
the belt in registration with a previously formed xerographic
powder image on the belt.
As previously stated the double-acting rotary solenoid 554
comprises a pair of pan-cake solenoids SOL-1 and SOL-2 and, is
arranged to produce rotation of the shaft 546 in either direction
without the usual incidental movement in the axial direction. In
accomplishing this function, the "up" solenoid SOL-1 has its
armature 574 in the form of a flat disc and arranged to be rotated
in one direction when the solenoid is energized and, the "down"
solenoid SOL-2 has its armature 575 also in the form of a flat disc
arranged to be rotated in the opposite direction when this solenoid
is energized.
The disc armatures are arranged in parallel planes and have their
axes in alignment. Each is formed with an axial opening through
which a rotary element 576 extends and is secured to the armatures
to be movable therewith as a unit. The element 576 slidably
receives the actuator 553 and is provided with internal teeth that
mesh with the splined exterior surface of the actuator to which is
connected the tongue 551 and groove 550 as a driving connection to
the shaft 546 for the lower registration roller 521. As each of the
armatures 574 and 575 is moved by its respective energized solenoid
coil, it moves the element axially along the actuator and moves the
other armature away therewith.
Upon energization of either of the coils for the solenoids, the
respective armature will be driven in rotational movement. This
rotary motion is produced by the cooperative action of a plurality
of balls 577 rotatably held within a pair of coacting inclined
depressions 578 formed one on the outer surfaces of each armature
and the other cover plates 579 which may surround the solenoids as
a casing therefor. The depressions 578 are disposed so that their
longitudinal axes and therefore, the inclined surfaces are circular
having a radius of curvature on the axes for the armatures. Each of
the cover plates 579 and armature associated therewith are held one
parallel to the other and close enough so that the balls are
retained within the inclined depressions in the armatures and their
co-acting inclined depression 578 in the cover plates.
In operation, when the solenoid SOL-2 is energized and the other
SOL-1 de-energized, the armature 575 is attracted to the coil for
SOL-2. This causes the element 576 to slide to the right, as viewed
in FIG. 42 without producing axial movement of the actuator 553.
Movement of the element 576 causes the other armature 574 to be
driven toward the adjacent cover plate 579, this is, from the
position shown in FIG. 44 to that shown in FIG. 45. The normal
magnetic action of the coil for the solenoid SOL-2 would want to
force the armature to the right as viewed in FIG. 10. Since the
balls 577 prevent axial motion directly, the magnetic force will
cause the balls to move along the inclined planes of the
depressions 578 on the plate 579. Because of the locking action
between the balls and the leading edges of the inclined planes of
the depressions formed in the armature 574, the same will be caused
to rotate. The armature 574 will rotate in an amount determined by
the length of the depressions 578 and the distance the armature is
allowed to move axially. For purposes of actuating the upper
registration roller 520 into a paper feeding position and to
reposition the fingers 555, the amount of angular rotation
desirable is approximately 45.degree..
In the event the "up" solenoid SOL-1 is energized, the armature 575
will be rotated in the opposite manner as the armature 574.
Regardless of which of the solenoids are energized, both armatures
with the elements 576, secured therebetween will move as a unit and
will slide relative to the actuator 553. However, the actuator will
be rotated, the direction being determined by which of the
solenoids being energized. With the "up" solenoid SOL-1 energized,
the roller 520 will be held in its uppermost position and the
fingers 555 in a sheet engaging condition.
DOUBLE SHEET SENSING MECHANISM
To sense the delivery of multiple sheets of paper to the transport
16 wherein the developed xerographic image is transferred to a
sheet of paper, there is provided a double sheet sensing mechanism
illustrated in FIGS. 50 and 51 which is adapted to signal the
presence of two or more sheets and, if desirable, to interpose a
reject finger into the path of movement of the sheets in order to
deflect the sheet into a suitable paper tray and prevent the
possibility of two or more sheets entering the transfer station for
the xerographic machine. The multiple sheet sensing mechanism is
generally indicated by the reference numeral 580 and illustrated in
detail in FIGS. 51 and 52.
The sensing mechanism 580 includes a depending bifurcated base 581
secured to a support bar 582 mounted at its ends upon the base
plates 401, 402 of the paper feeder mechanism 18. Pivotally mounted
at the lower end of the bifurcated frame 581 by means of a pivot
pin 583 extending through both legs of the frame is a movable frame
member comprising two identically shaped and parallel arranged
plate elements 584, 585. The plates 584, 585 are in the form of a
bell crank with the pivot pin 583 extending through the apex
thereof and one of its legs being adapted to support a pivot pin
586 for pivotally supporting a sensor shoe 587 thereon.
The other leg for each of the plates 584, 585 are joined together
by means of a block 588 having a bearing surface arranged in
cooperative relationship with an adjusting cam 589 mounted for
camming rotation upon the support bar 582. A spring plunger 590 is
threadedly received in the bar 582 and is made engageable with the
rear surface of the block 588 in order to provide positive pressure
against the cam 589 when the latter has been turned to affect
proper setting of the sensor shoe 587. Proper setting of the cam
589 can be made by a suitable knob 591 secured to one end of the
cam 589 and held rigid by a locking screw 592 engageable with a
portion of the cam screw.
The sensor shoe is preferably formed with an outer layer arranged
so as to be in the path of movement of one or more sheets of paper
being fed by the paper handling device 18 and forced into the paper
chutes 482, 483. The shoe is adjusted to be one and one-half paper
thickness in proximity of a roller 593 mounted for rotation on a
suitable pivot by means of a cross bar 594 also secured at its end
to the base plates 401, 402 of the paper handling mechanism 18. The
roller 593 is in frictional engagement with an idler roller 595
which in turn is in frictional engagement with the lower
registration roller 521 from where motion is imparted thereto. As
shown in FIG. 50 the lower registration roller 521 rotates in a
counterclockwise direction which by means of the idler roller 595
will impart counterclockwise rotation to the roller 593, which
direction is the same as the movement of a sheet of paper passing
between the cooperating surfaces of the roller 593 and the shoe
587. Normally the shoe 587 is biased in a counterclockwise
direction about its pivot 586 by a torsion spring 596 held in
tension between an anchor pin 597 secured to the plate 585 and the
shoe 587 against which the other end of the spring is engaged.
In order to control the progress of sheet movement between the shoe
587 and the roller 593 for each of sheet paper being fed into the
xerographic transfer station, the shoe has secured thereto and
movable therewith an actuator arm 598 which is arranged to engage a
leaf spring actuator 599 during rotating movement of the sensor
shoe 587 in order to actuate a normally closed switch SW-6 to an
open position. In FIG. 50 the solid lines for the elements 598 and
599 illustrate the positions of these parts when a sheet is not
being fed to the transfer station.
During normal operation, a single sheet of paper being forwarded to
the transfer station by the registration rollers 520, 521 will be
directed by the paper chutes 582, 583 between the sensing shoe 587
and the roller 593. With the sensing shoe and the roller being
spaced slightly greater than the thickness of the sheet of paper,
as the sheet is conveyed, the frictional pad on the sensing shoe
will ride over the top surface of the sheet. This is achieved by
the position of the cam 589 which may be adjusted so that the shoe
587 is spaced from the roller 593 one and one-half times the
thickness of the sheets being used. In the event that two or more
superposed sheets are driven between the chute 587 and the roller
593, the additional thickness of the sheets will cause rotation of
the shoe 587 to produce actuation of the switch SW-6. This
actuation may be utilized in a reject mechanism which may include a
solenoid for causing reject fingers to be interposed in the path of
movement of the sheet for deflecting the same into a suitable tray
and out of the transporting system for the sheets of paper.
After a single sheet of paper has been transported through the
double sheet sensing device by the rollers 520, 521 the sheet is
directed by these rollers into the horizontal transport mechanism
16 for presenting the sheet to the transfer station C whereat the
developed electrostatic image on the selenium belt 12 will be
transferred to the under surface of the sheet as the same is moved
in unison while in the transport in order to transfer the image to
the sheet.
TRANSPORT MECHANISM
The transport 16, as shown in FIGS. 52, 53 and 54 comprises a
relative flat fine structure formed by two transversely extending
fine elements 600, 601 to which are attached side elements 602, 603
arranged in spaced apart relationship. The input side of the
transport 16, or that side into which the sheet of paper is
introduced is provided with an upper roller 604 mounted on shaft
605 rotatably retained by suitable bearings upon openings formed in
the adjacent ends of the side plates 602, 603. Actually the shaft
604 comprises a plurality of resilient rollers 606 mounted on the
shaft 605 for rotation therewith and which are adapted to project
downwardly slightly from an upper flat grid-like guide member 607
which guides a sheet of paper thereunder. The guide member 607
cooperates with a lower grid-like member 608 mounted on a
transversely extending support member 610 so that the planes of the
guide members are parallel and closely spaced to permit a sheet of
paper to be moved therebetween and therealong. A lower roller 611
also mounted on the support member 610 projects through the
grid-like structure 608 and cooperates to assist in the movement of
a sheet of paper through the transport 16 at this point.
At the output end of the transport 1y, the ends of the side
elements 602, 603 are formed with suitable apertures for supporting
bearings through which a drive shaft 612 is rotatably mounted. The
drive shaft has secured thereto at one end outboard of the side
element 602 a sprocket 613. Similarly, the shaft 605 terminates in
a sprocket 614 positioned on the outboard side of the element 603.
A chain 615 encircles both sprockets 613, 614 and an idler sprocket
616 rotatably mounted on a stub shaft 617 adjustably mounted in a
slot 618 formed in the side element 602 to permit the adjustment of
the sprocket 616 and the tension on the chain 615.
Also mounted in the transport 16 on the side elements 602, 603 is
the transfer corotron 19 which is arranged as part of an integral
channel member 620 which contains a detack corotron 621 located
slightly downstream from the transfer corotron 19. The corotrons
19, 621 are connected by conductors 622 to a suitable source of
electrical power for energizing the corotrons in order to
accomplish their respective functions.
The frame structure for the transport comprising the frame elements
600, 601 and side elements 602, 603 is pivotally mounted by
suitable bearings upon the shaft 612 in order to permit rotative
movement of the transport out of the paper path and the clearing of
paper jams in the event such occurs or, to perform any other
maintenance at this station. The shaft 612 terminates at one end in
a socket 623 secured by an aligned adjusting rod 624 to the machine
frame plate 54a. The other end of the shaft is formed with a groove
adapted to receive a tongue formed on an adjusting rod 625
adjustably mounted in retaining thimble 626 mounted upon the main
frame plate 54. The socket 623 and the rod 625 are such as to hold
the transport frame by cantilever action in the position shown in
FIG. 40 in full lines but to permit pivotal movement to the
position shown in dotted lines. This arrangement permits rotation
of the frame 600, 601, 602, 603 about the axis of the shaft 612.
The frame may be retained in its uppermost pivoted position by a
spring latch 627 secured to a support brace 628 also mounted
between the frame plates 54, 54a. As shown in FIG. 53 by the dotted
line, the transport 16 may be pivoted and held away from the
selenium belt 12 and the other structure included in the movement
of the sheet of paper such as the roll 611 and the guide element
608.
As shown in FIG. 53 a sheet of paper W is shown in position that it
would occupy during the transfer of an electrostatic image while
being moved by the transport 16. While moving past the transfer
station C, the latent image on the selenium belt 12 comes in
contact with the under surface of the sheet W and, in cooperation
with the transfer corotron 19, the image is transferred to the
under surface. Immediately after the transfer of portions of a
developed latent image, the sheet of paper has applied thereto an
AC bias by the detack corotron 621 in order to overcome the
electrostatic forces which normally hold the sheet W upon the belt
12. This detack charging neutralizes the charge on the leading edge
and the other portions of the sheet of the belt 12 and, cooperates
with an air puffer having nozzles 630 to continue stripout of the
paper mechanically as it is moved from the surface of the belt 12.
The charge upon the upper surface of the sheet W by virtue of the
AC detack corotron 621 has a residual charge which permits the
sheet to adhere to a guide plate 631. The guide plate 631 comprises
a plurality of flat strips of metal against which the sheet W
slightly adheres as it moves into the fuser assembly 21. The strips
631 are suitably mounted upon a channel 632 secured to a top frame
plate 633 for the xerographic machine. A slow moving electric fan
634 mounted across the plates 54, 54a and arranged to convey air
upwardly provides a slight negative pressure upon the upper surface
of the sheet of paper W which tends to lift the sheet against the
upper guide member 607 during travel of a sheet through the
transport system.
It will be noted that the sheet W, after transfer of the developed
electrostatic image thereon, is conveyed upsidedown or in such a
manner that the transferred powdered image is on the under surface
of the sheet. Any movement of the sheet of paper from this point on
such as the sliding movement relative to the guide plate 631 will
be upon structure that is positioned above the sheet and in contact
with its upper surface in order to prevent smudging or smearing or
any contact whatsoever with the yet unfused powder image. As is
known in the art, the developing material used to form the powder
images are specifically designed to permit the images to be fixed
to sheets of paper by heat fusing, that is, the individual toner
particles or resin softened and coalesce when heated so that they
become sticky and readily adhere to the paper. With the shafts 605
and 612 being operationally connected by the chain 615, these
shafts move in unison in the same direction for rotating the
rollers 606 and 611 and transmitting sheets of paper. Adjacent the
sprocket 613, a pulley 635 is secured to the end of the shaft 612
and is connected by the timing belt 68 to a drive system, to be
described later, for the transport system.
FUSER APPARATUS
As shown in FIGS. 55-61 the fuser apparatus 21 is of the oven type
and includes a main housing 650 formed with an upper section
housing 651 in communication with the interior of a lower section
housing 652 and, an electric motor M-5 for maintaining circulation
of the heated air within the fuser housing 650. The walls of the
sections 651 and 652 are preferably made from thick heat insulating
material for minimizing heat losses through the walls.
Direct fusing of a particulate toner image on the lower surface of
a sheet of paper W is achieved by forwarding the sheet bearing the
power image to be fused through a slot 653 formed in the wall of
the upper housing 651 by means of the guide plates 631 on the
transport 16. As shown in FIG. 53, the plates 631 extend to the
slot 653 and the sheet W is adapted to bridge across the fuser end
of the strips 631 until the leading edge of the sheet is picked up
by the conveyor system for the fuser 21. The fusing occurs while
the sheet W is transported through the upper fusing housing 651 by
virtue of the convection and radiation and, to a limited extent,
some conduction of heat during the paper travel.
The conveying system for the fuser apparatus comprises a relatively
wide, single, endless belt 655 having a width greater than the
width of a sheet of paper being conveyed thereby. The belt is
formed with many small apertures and is arranged to be driven
around two rollers 656, 657 mounted transverse to the paper travel.
The roller 656 is arranged at the input section of the fuser or
adjacent the entrance slot 653 in order to present to the belt 655
the leading edge of a sheet of paper entering the fuser
housing.
The roller 656 is supported on a shaft 658 supported by bearings
mounted on each end of a U-shaped support device 659 secured to the
outer walls of the housing 651. The other support roller 657 for
the conveyor belt 655 is supported for rotation upon a shaft 660
mounted at one end in a bearing secured to one end of a U-shaped
support device 661 and, at the other end to a drive system to be
described hereinafter.
As the sheet of paper bearing a transferred powder image enters the
housing 651 it comes in contact with the moving belt 655 in an
inverted condition. This is accomplished by means of a vacuum
plenum 662 arranged between the two runs of the belt and adapted to
provide a reduced pressure upon the lower run of the belt for
lightly maintaining the sheet against the lower run to be carried
thereby. The apertures formed in the belt 655 insure that there is
a gradual flow of air from the space below the lower run of the
belt toward the space between the runs of the belt.
As the sheet of paper enters the housing 651 and becomes positioned
to be conveyed by the belt 655, successively moving portions of the
inverted toner image are immediately influenced by a steady flow of
hot air which is of sufficient temperature as to cause the toner
particles to become tacky in this preheat condition. This preheat
condition continues for most of the belt travel and is provided by
a heating and conveying apparatus to be described below.
In the lower heating chamber 652 there is formed an inner chamber
663 into which is positioned a rotatable impeller 664 supported and
driven by a drive shaft 665 arranged axially thereof and connected
to a motor M-5 adapted to imparting rotation to the impeller 664.
Within the impeller 664 and arranged generally along the axis
thereof and the shaft 665 is a heater coil 666 comprising
relatively large diameter heat conducting material connected to a
terminal 667 which in turn is connected to a suitable source of
electrical power to be energized thereby.
The impeller 664 is provided with vanes arranged in a pattern such
that upon rotation of the impeller, air will flow axially in toward
the center space of the impeller vanes from the space below the
impeller and then radially outwardly from the general direction of
the axis of the impeller toward and through the impeller vanes.
During energization of the motor M-5, air then is conveyed from
within the internal space of the impeller where the air is
continually heated by the coil 666 and then driven outwardly into
the lower heating chamber 663. This air is conveyed out of the
chamber 663 through an opening 668 formed in a separation wall 670
separating the chamber 663 within the housing 651 from a layer
chamber 671 within the housing 651.
As the hot air under pressure leaves the chamber 663 and enters the
chamber 671, it becomes slightly reduced since the chamber 671 is
larger. This is effective to aid in directing heated air to the
toner image on the sheet W that is under low pressure but of high
volume and of sufficient temperature to preheat the toner particles
in the image to the tacky condition referred to above. This flow of
air also maintains the sheet of paper against the lower run of the
belt 655. In this stage of heating of the toner image, the same is
affected by convection type heating.
The second heating stage that the powder image on the sheet
experiences is in the form of radiated heat produced by a pair of
parallel arranged linear infrared heat lamps 672 arranged
transverse to the paper travel, slightly below the lower run of the
belt 655 and in a position just before the belt moves out of
conveying relationship with a sheet in traveling around the roller
657. The lamps 672 are arranged in side by side relationship and
each is arranged at the focal point of concave reflectors 673. The
adjoining edges of the reflectors are secured together and are
supported by a strip of metal 674 secured at its lower edge upon
the separation wall 670. The heat lamps 672 are preferably of the
quartz infrared type which are capable of producing relatively high
heat quickly. The reflectors 673 are formed with a plurality of
small openings 675 which provide communication between the interior
chambers for the reflectors and the space surrounding the outer
confines of the reflectors, this later space being connected by a
narrow transversely extending passageway 677 formed in the lower
wall 678 of the housing 651. Some of the air produced by rotation
of the impeller 664 is conveyed by the passageway 677 and the
openings 675 into the interior of the reflector 673 under a slight
pressure in order to enhance the heating effect produced by the
lamps 672. In addition, the heat produced by the lamps 672 is added
to the heat produced by the coil 666 before being applied to the
tackified image on the sheet W.
Throughout the time during which the sheet W is within the chamber
671 of the upper heating house 651 and during the operation of the
heating means produced by the heating coil 666 and the impeller 664
and the heat produced by radiation from the lamp 672, the sheet is
continually heated to some extent by conduction on the upper
surface thereof. This heating by conduction is produced by a quartz
infrared lamp 680 mounted at the apex of focus line for a reflector
681 having a configuration similar to that of the reflectors 673
arranged to concentrate heat rays upon the belt 665 as the same
commences its return run preparatory to the picking up of another
sheet of paper. The lamp 680 and the reflector 681 are suitably
mounted by a bracket 682 to the sides of the housing 651 in a
position to heat the belt 655 while the same is being run on the
roller 657. This heating of the belt has two functions, one to
present a heated conveying means which will be in intimate contact
with a sheet of paper entering the fuser at a relatively cool
temperature or, at least relative to the heat within the fuser
interior. This eliminates the prospect of the belt 655 becoming a
heat sink for the heat being absorbed by the sheet as it enters and
becomes attached to the belt. The other function of the heating
means produced by the lamp 680 is to provide heat by way of
conduction to the powder image on the sheet of paper.
With the toner image now completely fused by the combined action of
the convection air produced by the coil 666 and the impeller 664
and the irradiated heat produced by the lamps 672 and with the aid
of the heat produced by conduction on the belt 655 by the lamp 680,
the sheet is now conveyed through a rear opening slot 683 formed in
the rear wall of the housing 651. In leaving the fuser assembly 21,
the sheet of paper is conducted by a short running conveyor system
22 to a suitable output tray 23.
During continuous operation of the fuser apparatus 21, the motor
M-5 remains continuously energized in order to continuously impart
rotation to the impeller 664. Continuous movement of the belt 655
is maintained by a drive system connected to the shaft 660. The
drive system includes a timing pulley 684 connected by a belt 685
to a timing pulley 686 connected to the shaft 612 on the horizontal
transport 16. Air is continuously circulated throughout the entire
outer housing 650 by virtue of the rotation of the impeller 664.
The air that is directed through the opening 668 is expanded as it
enters the chamber 667 and impinges upon the powder image on the
sheet of paper W. The air is then directed upwardly through and
around the conveyor belt 665 and rollers 656, 657 and conveyed back
to the space below the impeller 664 and into the interior space
thereof by means of a duct 687 (see FIG. 59) which is in
communication with the upper regions of the interior of the housing
655 and with a chamber 688 formed in the lower section of the lower
housing 652 below the lower end of the impeller as indicated by the
flow arrows. This movement of air creates the previously described
vacuum conditions in the plenum chamber 662 and the vacuum, in
conjunction with the upward flow of air from the chamber 663,
maintains each sheet of paper entering the fuser assembly against
the conveyor belt 655 to permit movement thereby.
Also, by maintaining a closed loop air flow pattern, that is, a
re-heat recirculating system, high heating efficiency is achieved
since there is relatively little heat loss and this may be made up
by a substantially reduced heat input. In order to minimize the
time in bringing the temperature within the fuser assembly to a
predetermined optimum valve, the entry slit 653 for the housing 650
through which sheets of paper are conveyed by the transport 16 and
the exit slit 683 are provided with gates 695, 696 respectively
which are adapted to close their respective slots during the
warm-up period for the reproduction machine. A solenoid SOL-3 is
connected to each gate for actuating the same upon the reception of
control signals as will be described hereinafter.
MAIN DRIVE SYSTEM
The combined operation of the sheets feed mechanism 18, the sheet
transport mechanism 16, the fuser assembly 21 the selenium belt
assembly 11 and the developer assembly 14 consisting of the
vertical transport arrangement and the horizontal conveying
arrangement is provided by a drive system illustrated in FIGS. 61
and 62 and under control of an electric circuit to be described
hereinafter to insure proper component coordination in time
sequence during machine operation. In FIG. 61 and 62, the motor M-4
is provided with a gear reduction device 700 having an output shaft
701 and two pulleys mounted thereon for rotation during
energization of the motor M-4.
The first pulley on the shaft 701 and designated by the numeral 702
is connected by a timing belt 703 to the pulley 515 on the shaft
513 for the sheet separating apparatus in the paper handling
apparatus 18. The belt 703 is also directed around the pulley 539
for imparting a driving rotation to the upper registration roller
520. As shown in FIG. 61, the belt 703 is directed around an idler
pulley 704 and 705 in order to provide a means for adjusting the
tension on this belt and also for producing proper direction of
movement for the pulleys 515 and 539. The other pulley 706 in the
pair of pulleys on the shaft 701 is connected by the timing belt 68
for imparting drive to the pulley 67 for eventually effecting drive
to the selenium belt assembly 11 and to the pulley 635 mounted on
the shaft 612 for the transport 16.
Another motor, M-7 in the main drive system, has a drive pulley 707
connected by a timing belt 708 to a pulley 710 secured to one end
of the shaft 264 which serves to drive the developer return
mechanism comprising the internal bucket conveyor belt 236 within
the return housing 227. Another pulley 711 is also driven by the
motor M-7 and is connected by the timing belt 278 to the pulley 277
secured on the shaft 228 which drives the two screw conveyors 226
and 247.
From the foregoing description of the main drive system for the
sheet feed mechanism 18, the transport 16, the fuser assembly 21,
the selenium assembly 11 and the developer system 14, it will be
appreciated that upon energization of the motors M-3, M-4, and M-7
these components will commence and remain in operation in timed
sequence.
BELT CLEANING MECHANISM
The belt cleaning assembly 25 shown in FIGS. 63-65 comprises the
rotatable brush 720 of such construction as to apply extremely
light pressure to the photoconductive surface of the selenium belt
12 and to dislodge any powder particles that may adhere thereto.
The brush is preferably formed of synthetic fur secured to a rigid
cylinder 721 and is supported at its left end by a truncated cone
shaped plug 722 formed with serrations thereon to grip the internal
surface of the cylinder for rotation therewith. The plug 722 is
fixed by a pin 723 to a shaft 724 of a motor M-9 mounted in a frame
725, bearings 726 being positioned within the frame and surrounding
the shaft 724 for rotatably supporting the shaft. At its opposite
end the cylinder 721 is supported by a second truncated cone shaped
plug 727 provided with serrations thereon similar to the plug 722
that is rotatably and movably mounted by a bearing 728 to a stub
shaft 730 fastened at a casing cover 731 secured by nuts to a
housing 732 which serves to contain the brush 720. A coil spring
733 encircles the shaft 730 between the internal surface of the
cover 731 and the adjacent end of the bearings 728 in order to
permit limited axial movement of the plug 727 for permitting easy
removal of the brush 720 and maintain constant pressure on the
drive arbor for the brush despite variations in brush length.
For containing toner powder particles removed from the belt 12 by
the belt cleaning device, the housing 732 encompasses approximately
the entire brush area and as shown in FIG. 64 when applied to the
belt 12 the opened end of the housing is nearly rendered closed by
the adjacent surface of the belt. In order to insure as close as
possible an air tight relationship between the selenium belt 12 and
the interior of the brush housing 732 the upper edge portion of the
housing is provided with an adjustable seal plate 734 which may be
moved circumferentially relative to the housing wall in order to
permit close positioning of the leading edge of the seal plate to
the selenium belt during movement thereof. Similarly the lower wall
section of the housing 732 is provided with an adjustable seal
plate 735 which has a leading that may be moved toward and away
relative to the belt 12 in order to minimize the spacing
therebetween.
At the other end remote from the side thereof which faces the
selenium belt, the housing 732 is formed with an exhaust opening
736 in the form of an elongated slot having its axis parallel to
the axis of the brush cylinder 721. An adapter 737 is fastened to
the housing 732 by suitable screws 738 and is formed with an
opening conforming to the opening 736. The adapter serves to
connect an exhaust duct 740 to the housing. The exhaust duct 740
may be connected to a suitable high volume, low pressure vacuum
system in order to continuously exhaust toner particles
accumu1ating within the housing 732 during brush cleaning
operation.
In order to aid in the removal of toner particles from the bristles
of the brush 720 during rotation thereof, the belt cleaning
assembly is provided with a flicker device including a flicker rod
or bar 741 mounted between the exhaust slot 736 and the brush and
extends throughout the length of the housing 732 parallel to the
axis of the cylinder 721. Actually the flicker device comprises the
rod 741 and a flicker plate 742 in the form of a curved sheet metal
plate extending the entire length of the housing 732 in the path or
in alignment between the axis of the cylinder 721 and the exhaust
opening 736. The flicker bar 741 is spaced slightly from the
interior edge of the plate 742 and serves as the leading edge
thereof interposed in the path of movement of the bristles for the
brush 720 in order to cause flickering thereof.
The rod 721 is held between a thin ribbon 743 formed from the
material of the plate 742 at each end thereof as shown in FIG. 65
and a flat spring element 744 secured by rivets 745 to the ribbon
material 743 at each end thereof. The spring 744 is formed with an
angled or curved portion 746 spaced from the ribbon 743 and between
which the end of the rod 741 may be placed under spring bias
provided by the element 744. The structure 743, 744 and 746 are
provided at each end of the flicker plate 742 in order to
releasably hold the flicker rod 741. These structures also permit
rotation of the rod 741 which occurs by the continuous engagement
of the moving bristles on the brush 720 during rotation
thereof.
During cleaning operation using synthetic fur brushes 720 to clean
a photoconductive surface such as a xerographic plate 12 there has
been found severe filming of toner particles of the surface after
short use thereof. The cause of this filming has been traced to
some degree to the impaction of toner particles onto the brush
bristle tips which occurs where the bristles strike the
conventional stationary flicker bar. It has been found that the
filming occurs since the toner build up on the fixed flicking bar
leading edge where it contacts the bristles and becomes "tar-like"
after several cycles with the tar-like toner being transferred to
the bristle tips and in turn to the photoconductive surface being
cleaned. The rotation of the flicker rod 741 minimizes toner
buildup because of the continuously changing surface area exposed
to the bristles at any one instant of time and the cooler
temperature provided by a moving area such as afforded by a
rotating rod.
For optimum cleaning situations, the bar 741 is coated with
material having triboelectric properties matched with the brush
bristles and the polarity of the preclean corotron 24. Like charges
on the flicker bar with those produced by the preclean corotron and
with the opposite charge on the brush bristles, as induced by the
bar, will give optimum cleaning of residual toner particles having
charges opposite to that of the bristles.
During operation of the belt assembly 25 the rotating bristles of
the brush 720 continuously wipe off the residual toner particles
resting upon the belt 12 as it moves from the transfer station of
the machine to the charging station thereof. The residual toner
particles are pulled off the surface of the belt and brought into
contact with the flicker rod 741 thereby becoming disengaged from
the brush bristles and allowed to be sucked through the exhaust
adapter 737 and into the exhaust duct 740. A filter mechanism may
be attached to the remote end of the duct 741 in order to receive
the air entrained toner particles for separating the same and
permit reclaiming of the toner particles. The vacuum system
utilized with the duct 740 produces a flow of air through the brush
cleaning housing 732 drawing air through the narrow slits between
the seal plates 734 and 735 and the adjacent surface of the belt
12.
SELECTIVE DEVELOPMENT CONTROL
The xerographic machine previously described is adapted to copy
originals and produce multiple copies thereof at a relatively high
rate of speed. With provision for solid area coverage and a
developing system which is adapted to supply toner particles to an
electrostatic latent image in relatively high quantity, it is
desirable that means be provided for controlling development either
directly or indirectly in order to effect development only during
those times in which a latent image is actually being processed. To
this end there is provided with a selective development control
arrangement, see FIGS. 2 and 66, which will selectively dissipate
the charges upon the selenium belt during those period in which an
original, has not been exposed which result in the formation of
narrow strips between electrostatic images moving upon the belt,
the initial movement of the belt before the machine is conditioned
to trigger the first exposure and during the production of the last
copy immediately after the trailing edge thereof is being moved
into the development zone of the machine.
Since the electrical inertia and hysteresis effects limit the
"Off-On" response time for corotron energization, the charging
corotron 13 for the xerographic machine remains "On" during the
complete printing cycle operation for the machine. With the
charging corotron continuously placing a solid charge upon the
selenium belt, the development control circuit is arranged to
dissipate the charge in those areas of the moving belt where
exposure has not been provided in order to prevent development of
these areas and consequently minimize the loss of toner particles
occasion by developing a solidly charged area of the belt.
The control circuit includes a discharge fluorescent lamp LMP-5
which is mounted in a suitable housing 750 secured to the base of
the machine and arranged so that the lamp extends transversely
across the path of movement of the selenium belt 12 after the same
traverses the exposure station A.
The end coils for the lamp LMP-5 are connected respectively, to a
secondary coil TS-2, TS-3 of a transformer TR. The primary TP for
the transformer TR is connected to a suitable source of 120 volt 60
cycle electrical power. The transformer TR also includes a third
secondary coil TS-1 which is adapted to step up the voltage and is
connected to a full wave rectifier having positive and negative
output terminals 751, 752, respectively. Preferably the output of
the rectifier is approximately 300 volts DC and each of the
secondaries TS-2, TS-3 capable of producing 6.3 volts.
With the two secondary windings being connected to the lamp coils
as previously stated, the energization of the transformer primary
TP will cause energization of the coils within the lamp tending to
cause illumination thereof. However, with the center tap of the
transformer secondary TS-2 being connected to the positive terminal
751 for the rectifier, the amount of energization provided for the
lamp is sufficient to maintain the temperature of the gas therein
at a sufficient temperature just below the threshold necessary to
cause illumination thereof. As will be described hereinafter during
description of the operation and electrical circuit for the
xerographic machine this condition of the lamp LMP-5 is maintained
during standby condition of the machine and in those periods when
the lamp is not in illumination condition. The lamp circuit however
is arranged such that with a proper input signal thereto additional
energizing current is supplied to the two lamp coils in order to
trigger the lamp to full illumination condition.
By maintaining the standby energization thereof just slightly below
that voltage necessary to produce full illumination and allowing an
extremely short duration pulse to trigger the lamp circuit to cause
full illumination thereof, the pulse may be extremely short
duration and the response time for the lamp to arrive at its full
lumen output will become likewise extremely short. These time
periods, that is, the duration of the input triggering signal and
the response time in which the lamp achieves full illumination from
a darkened or non-illumination condition and then reverts back
again to a non-illumination condition can be measured in micro
seconds.
In order to accomplish this short duration illumination response
time, the transformer secondary TS1-3 has its center tap connected
to the collector of a first transistor TR-1 which is normally
maintained in a quiescent state. The emitter for this transistor is
connected to the start shield 753 for the lamp LMP-5 and has its
other end connected to the negative terminal 752 of the rectifier.
Conduction of the transistor TR-1 will provide a small DC voltage
to the start shield 753 in order to accomplish an additional
triggering voltage to the lamp LMP-5 to effect the additional
voltage bringing this lamp to full illumination condition.
In order to control conduction of the transistor TR-1 the base
thereof is connected to the emitter of a second transistor TR-2
having its collector connected to a source of DC current on the
order 24 volts. The bases for the transistors are connected
respectively by diodes D-1, D-2 to the connection between the
emitter for the transistor TR-1 and the shield 753 in order to
provide leakage compensation for the circuit. The transistor TR-2
is normally held in a non-conducting state, however it is triggered
into conduction by means of a pulse signal from the logic circuits
indicated by the reference letter L for the xerographic machine to
which the development control circuit is applied. The signal is
connected to the base of the transistor TR-2 by way of a Zener
diode Z and a variable resistor VR connected in series between the
base of the transistor and the logic circuit. The pulse signal from
the logic circuit is adapted to drive the transistor TR-2 thereby
rendering the transistor TR-1 conductive for the DC power supply
which supply is instantaneously connected to the shield 753 to
provide the additional voltage for the lamp LMP-5 to produce full
illumination thereof.
The machine logic L is arranged so that a pulse signal is generated
for illuminating the lamp LMP-5 a short predetermined period of
time after de-energization of the exposure lamps in the
illumination system 10 for the xerographic machine. These occasions
occur between each exposure on the selenium belt 12 which, in the
event multiple copies of a single document are being made, is in
the short interval that normally results in the spacing between the
sheets being copied. The logic circuit L is also adapted to provide
a continuous signal for the lamp LMP-5 during a time that the
machine is turned "on" when belt charging and development operation
occur and just prior to the first illumination cycle of the system
10. Another time in which a continuous control signal is generated
is after the short predetermined period of time after the last
flash of illumination produced in the system 10 when belt charging
and developer operation continues just prior to the time the
machine goes into its shutdown mode. This short predetermined
period of time referred to is determined by the time required for
the belt 12 to travel in order that an electrostatic image thereon
is clear of the influence of the lamp LMP-5.
During those times that the discharge lamp LMP-5 is illuminated,
the uniform charge placed upon the selenium belt 12 by the charge
corotron 13 is erased since the light exposure by the lamp LMP-5
will cause conduction of the photoconductor on the selenium belt.
Upon each of these occurrences, the area of the belt affected by
the lamp LMP-5 will not carry a charge and therefore will not be
developed as these portions of the belt traverse the development
station B. With this arrangement it will be apparent only those
portions of the selenium belt which actually carry electrostatic
latent images of information to be copied or reproduced will be
treated at the development station B. At all other times especially
during the start up of the machine and the terminating processing
station will not result in the full development of uniform charged
areas which do not carry information to be reproduced. In this
manner there is little loss of toner or developer material during a
development process that is not necessary for machine use. With the
provision of the control circuit the charging corotron 13 may be
maintained in continuous energizing condition and the discharge
lamp control will, in effect, provide that necessary "On-Off"
requirement for determining whether the selenium belt will have or
not have charged images thereon.
MACHINE OPERATION AND ELECTRICAL CIRCUIT
A clearer understanding of the operation of the xerographic machine
and of the electrical circuit controlling the various components
can best be obtained by reference to the schematic wiring diagrams
of FIGS. 67 and 68 and the timing sequence chart of FIGS. 69 and
70.
Assuming that the power lines W-1, W-2 are connected to a suitable
source of electrical power and with the neutral line N connected as
shown in FIG. 67 and DC power supply PS-1 will be connected to a
source of electrical power to provide multiple outputs of different
voltages of direct current. The first operation on starting the
machine is for the operator to press the "Start" button or "on"
switch SW-1. The "On" switch SW-1, when closed, is connected in
series with a relay contact 2CR-1 and a main relay 1CR which has an
electrical connection with the neutral line N. In order to affect
machine operation, the normally open contact 2CR-1 must be actuated
to a closed condition in order to provide energization of the main
relay 1CR. The contact 2CR-1 is actuated to a closed condition when
the relay 2CR is energized and this is accomplished when the
machine is initially connected to the source of electrical
power.
The machine logic L also connected to the source of electrical
power is in warm up condition or that condition which permits full
operation of the logic system. Upon this occurrence a signal will
be generated by the logic L for energizing the relay 2CR, the
signal from the logic L functioning in the sam way as a circuit
interlock switching arrangement.
With the contact 2CR-1 closed to affect machine operation, the
operator pushes the "On" button for causing energization of the
main control relay 1CR. This latches in the main relay which closes
its own holding contact 1CR-2 by way of the closed "Off" switch
SW-2. Energization of the main relay 1CR causes closing of the main
relay contacts, 1CR-1, and 1CR-2 for providing electrical power to
the electrical machine components of the machine.
Closing of the main contact 1CR-2 in the main line W-2 closes the
circuit to the main vacuum motor M-1 which may be connected to a
vacuum exhaust system for providing vacuum for the plenum chambers
provided in the belt assembly 10 for holding the selenium belt 12
against the face plates 66, 67 and, a duct system for connection to
the brush cleaning duct 740. In addition to the motor M-1, upon
closing of the contact 1CR-2, the motor M-8 is also energized for
providing a negative pressure immediately above the paper transport
frame comprising the frame elements 600, 601, 602 and 603 for times
when a sheet of paper is transported from the registration rollers
to the fuser assembly.
In the timing charts of FIGS. 69, 70 it will be seen that during
the warm up phase of the machine operation, that is, the time
between closing of the "On" switch SW-1 and just prior to the
machine going on into "Standby" mode, the main vacuum motor M-1 is
energized and remains so for the entire machine operation. In
addition to this closing of the "On" switch the switch 1CR-1 in the
line W-1 also closes the circuit to the fuser heaters 672, 680
which provides electrical power thereto of approximately
2,500-3,000 watts for the quick warming up of these heaters, the
fuser main drive motor M-3 for the sheet conveyor device within the
fuser assembly 21 and, the motor M-5 for producing a vacuum in the
fuser vacuum platen 662 and for conveying warm air toward the toner
image upon a sheet of paper thereby preheating the same.
Closing of the contact 1CR-1 also provides electrical power to the
paper elevation motor M-2 which is under control of the "up" switch
SW-3 and the "down" switch SW-4. In the event that the paper tray
400 is in a position wherein the last few sheets of paper remain
the switch SW-8 will be actuated to a closed position by the
uppermost position of the tray thereby energizing the motor M-2 for
initiating the shutdown of the machine by a relay circuit under
control of relay 3CR and placing the machine in Standby condition
and driving the tray to a lowermost position permitting the
operator to add more sheets of paper thereto. In addition to the
motors M-2 and M-3, energization of the main relay 1CR causes
closing of the normally open switch 1CR-3 for providing electrical
power to the solenoids SOL-3 which, when energized, actuate the
normally open fuser flaps 695, 696 to their closed positions
thereby permitting a quicker warm up of the fuser. Lastly, the
initial closing of the "On" switch SW-1 provides for the
energization of the solenoids SOL-5 through a timer circuit and the
fuser control circuit FC which controls energization of the fuser
heater lamps 672 and 680. The circuit FC also provides power for
the control circuit to the thermostats THS-1 which controls the
temperature of the fuser conveyor belt 655 and the thermostat THS-2
which controls the air temperature within the fuser housing
chamber. The timer circuit for the solenoids SOL-5 is arranged to
provide energization periodically for the solenoids thereby
maintaining steady movement of toner through the hopper 300. During
initial start-up of the machine, when the contact 1CR-1 is closed
this energization is provided to insure adequate supply of toner
and movement thereof in the event the previous non-use of the
machine caused some settling of toner.
As shown in FIG. 69 in the timing chart for the operating cycles of
the xerographic machine, closing the "On" switch SW-1 initially
provides electrical power for the fuser main drive motor M-3, the
fuser vacuum motor M-5, the fuser flap solenoids SOL-3, the fuser
heaters 672, 680 and the main vacuum producing motor M-1. Except
for the fuser drive motor M-3, these components remain energized
during the Standby mode of the machine and remain so until the
Print operation is initiated. As the machine assumes "Standby," the
electrical power to the fuser heaters 672 and 680 is reduced to
approximately 500 watts where they remain until the machine is
placed in operation and, the fuser drive motor M-3 becomes
inoperative. When the temperature within the fuser housing attains
a predetermined temperature sensed by the thermostat THS-2, the
power to the fuser heaters is reduced to 500 watts. The machine is
now in condition to be operated for copying or duplicating
purposes.
In order to commence further operation, the operator, after placing
an original to be copied upon the platen P, will depress the
"Print" button to close switch SW-5 which in affect electrically
causes the grounding of the logic circuits L. Closing of the
"Print" switch effectively causes the energization of the shutdown
relay 3CR which closes a first contact 3CR-1 in the power line W-1
and the switch 3CR-2 in the power line W-2. Closing of these two
switches supplies electrical power to the remaining components of
the electrical circuit for the xerographic machine in the order to
produce copies of the document. In FIG. 69, the timing chart is
arranged so that the "Print" button actuation initiates the timing
cycle for machine operation and all component energization at this
point until shutdown of the machine occurs.
The timing cycle of operation is arranged in accordance with timing
increments of 1 second for each increment and wherein each second
is further sub-divided into four equal increments. As for those
components which are energized at the depression of the "Print"
switch, they will be described and discussed hereinafter in
accordance with the order of listing shown in FIGS. 69 and 70.
With the closing of the switches 3CR-1 and 3CR-2 by actuation of
the "Print" button, electrical power is supplied to the main drive
motor M-4 which supplies power to the paper feeder 18, the
transport system 16 and the selenium belt assembly 11. This
electrical supply remains continuous during the complete operation
of the machine thereby assuring continuous operation of the
components that are actuated. In addition, the development
electrode 210 and the entrance chute extension 211 are energized as
is the development control lamp circuit. Also energized when the
"Print" button is actuated are the DC and AC corotrons PS-2, PS-3,
respectively. With the AC power being supplied to PS-3, the detack
corotron 621, the preclean corotron 24 and the pre-transfer
corotron 755 are supplied with electrical power for energizing the
same for the entire operation of the machine. With the DC power
supply PS-2 energized, electrical power is supplied to the charge
corotron 13 and the transfer corotron 19.
The DC power supply PS-2 also supplied DC power having various
voltages to the development electrode 210, the entrance chute 211
and the pick-off baffle 202. This then completes the circuit to
those components enumerated above and illustrated in the timing
charts in FIGS. 69 and 70 at the instant that the "Print" switch is
closed. It will be noted that at "standby" condition, the fuser
heater lamps 672, 680 are supplied with approximately 500 watts of
electrical power which places the heater lamps into prefusing
condition which of itself is not sufficient to provide enough heat
for complete fusing or fixing of a toner image upon a sheet of
paper. This supply of power to the fuser lamps will maintain the
lamps in readiness for instant energization by a larger supply of
electrical power when needed, which time occurs after a
predetermined time period after the "Print" switch has been closed.
When in fusing condition, the electrical power to the fuser heaters
672, 680 is approximately 2,000 watts.
While not illustrated, the logic circuits L are provided with
suitable timing circuits which when conditioned for operation, are
adapted to provide signal pulses to the various control devices for
each xerographic processing component. As shown in the diagrams of
FIGS. 67 and 68 the dashed line from the logic circuits L indicate
the path of control pulses which serve to energize or de-energize
or otherwise influence the components connected thereto.
After a period of 1 second has transpired after the actuation of
the "Print" switch, the flash power supply for the illumination
lamps L-1, L-2, L-3, L-4 becomes energized in order to condition
the lamps for an instant supply of full power. With the flash power
supply PS-4 energized, the lamps are supplied with a voltage which
will cause illumination thereof when an appropriate trigger signal
is applied.
After an additional second has transpired, or 2 seconds after the
"Print" button has been actuated, the developer drive motor M-7 is
pulsed by the logic circuit L for energizing the same. This causes
the vertical conveying of developer material from the lower
conveyor screw 226 onto the vertical conveyor belt 236 and the
rotation of the upper conveyor screw 247 for initiating the
circulation of developer material within the developer assembly 14
just prior to the developing stage of machine operation. At about 3
seconds after "Print" switch actuation, the fuser heaters 672, 680
are energized with additional electrical power to bring them up to
2,000 watts.
This condition of each of the above described operations occurring
after the closing of the "Print" switch and those which were
energized during the "Standby" mode of machine condition remain
energized until the passage of slightly over 3 seconds from the
time the "Print" button was actuated which time period is
sufficient to bring all of the affected components to their full
operating condition. The next phase of operation occurs after the
referred-to 3 second period when the machine logic circuits L,
after it has since sensed the condition of all the affected
components, will produce a signal for the lamp trigger circuit PS-5
which will instantly supply that extra electrical power necessary
for each of the illumination lamps for bringing the same to full
illumination ability for a timed period measurable in microseconds.
The pulse signal then from the logic circuit L to the flash power
supply will also be directed to the lamp trigger circuit PS-5 which
will provide full illumination for the illumination lamps and cause
exposure of the selenium belt 12 thereby.
In exposing the selenium belt, an electrostatic latent image of the
original is produced in a manner well known in a xerographic art
and, with the selenium drive in operation, the area of the selenium
belt exposed will move downwardly toward the lower roller 46 and
toward the development control lamp LMP-5. As shown in the timing
chart of FIG. 69, this control lamp is de-energized approximately a
quarter of a second after exposure thus allowing time for the
selenium belt to move the latent image out of the influence of the
discharge lamp or, at the time the trailing edge of the
electrostatic latent image area is opposite the influence of the
lamp.
Approximately three-fourths of a second later or, after 4 seconds
after the "Print" switch has been actuated, the toner control
system will come into play and, as previously described, the 6
second toner control operation will commence. This has the affect
of energizing the toner timer motor M-6 for conditioning the toner
control system to sense the toner density in the developing system
every 6 seconds in order to control operation if necessary of the
toner dispenser motor M-10.
As the electrostatic latent image makes the turn at the lower
conveyor roller 47, it approaches the development zone determined
by the development electrode 210, 211. During movement through the
development zone, the cascading developer material flowing
downwardly between the development electrode and the selenium belt
moving upwardly, the electrostatic latent image becomes developed.
In this process step, toner particles are pulled away from the
developer material carrier beads and applied to the latent image
thereby producing a developed image of the original.
Approximately 2 seconds after exposure, the paper feed clutch coil
512 is energized upon reception thereof by a signal from the logic
circuit L. This action operatively connects the rotating drive
shaft 513 with the drive belt 516 in order to produce rotation of
the separating rollers 485, 486. After a sheet of paper has been
fed to the registration rollers 520, 521 and leading thereof is in
register with the register fingers 555, the paper feed clutch 512
is de-energized for the copying cycle affecting the particular
sheet of paper thus fed out from the paper feed mechanism.
Immediately after the paper feed clutch 512 is de-energized, the
"up" register solenoid SOL-1 is energized in order to insure that
the register fingers are in the up position to engage the leading
edge of the sheet of paper arriving thereat and that the upper
registration roller 520 is out of contact with the lower
registration roller 521. Immediately after this actuation, the
"down" register solenoid SOL-2 is energized in order to move the
register fingers out of impeding engagement with the leading edge
of the sheet of paper now between the registration rollers and to
affect downward movement of the upper registration roller 520 for
imparting feeding movement to the sheet of paper. At a time between
the energization of the solenoid SOL-1 and the solenoid SOL-2, the
signal from the logic circuit L will cause the de-energization of
the developer drive motor M-7 since at this time there is no need
to maintain the movement of the developing material into the
development zone of the machine.
With the sheet of paper being driven by the upper and lower
registration rollers, it is now within the influence of the
transport system 16 as the paper moves to the image transfer
station C. As shown in the timing chart 73, this action, which
comprises the time in which the sheet of paper is being transported
by the system 16 occurs for a period of approximately 1 second in
duration.
As the sheet of paper is being so transported, the developed
electrostatic image on the selenium belt 12 is transferred to the
under-surface of the horizontally moving sheet of paper when the
sheet is tangent to the belt while moving around the upper roller
45. Immediately after transfer of successive segments of the
developed image occur, the sheet of paper is stripped away from the
selenium belt as it is moved in curvature around the roller 45.
Immediately after the segments are transferred, the puffer solenoid
SOL-4 is energized by virtue of a signal from the logic circuit L
for causing a low pressure high volume, flow of air from the nozzle
630 for starting the separation of the leading edge of the sheet of
paper from the belt thereby permitting further separation of the
detack corotron 621. This corotron places an electrostatic charge
upon the upper surface of the sheet of paper for affecting the
attraction of the sheet to the upper plates 631 and away from the
selenium belt.
For the next second or more, the development electrode 210, 211
remains energized, in the event only one copy is being made, in
order to insure complete development of the electrostatic image the
last phases of which may be developed as the earlier stages or
leading edge thereof is transferred. Just prior to the
de-energization of the development electrode at approximately a
second and a half after the transfer of the electrostatic images
commences, the DC power supply PS-2 will be de-energized in order
to terminate energization of the charge corotron 13, the transfer
corotron 19 and the pre-transfer corotron 755.
As the latent image continues to be transferred to the trailing
portions of the sheet of paper, the leading edge of the sheet will
be directed into the fuser assembly 21 in order to insure fixation
of the developed transferred image thereon. As shown in the timing
chart FIGS. 69 and 70 just prior to the exposure of the original,
the fuser heater lamps 672, 680 are energized with additional
electrical power in order to bring the lamps to approximately 2,000
watts thereby effecting a temperature which is optimum for the
complete fusing of powder images at the speed in which the sheet is
transported through the fuser assembly. This high heat of the fuser
lamps continues until some time after transfer of the developed
image upon a sheet of paper whereupon a further signal from the
logic circuit L will return the fuser lamps to its "Standby"
heating condition of producing approximately 500 watts.
The timing charts in FIGS. 69 and 70 illustrate the energization
and timing of energization for some of the components of the
xerographic machine for the production of one copy of an original.
The entire process beginning from the actuation of the "Print"
switch takes approximately 10 seconds after which the logic circuit
L will control the machine components and revert the same into
"Standby" condition. This is accomplished by a circuit in the logic
system coupled to the shutdown relay 3CR for de-energizing the same
when the last copy being made has accomplished into its processing
steps. As previously described, at "Standby," the only machine
mechanisms that remain energized are the main vacuum motor M-1, the
fuser vacuum motor M-5, the fuser heater control FC and the fuser
flap solenoids SOL-3 to maintain closing of these fuser flaps. At
this point the xerographic machine is in condition for the
initiation of the print cycle to produce another copy of the same
original or a new copy of another original.
In the event that multiple copies of an original are to be
produced, some of the electrical components previously described
will cycle automatically periodically in accordance with the timing
arrangement provided in the logic circuit L. In the multiple copy
mode, the shutdown relay will remain energized permitting all
necessary components to function. Assuming that the xerographic
machine as described is capable of producing one copy per second it
will be apparent that exposure will occur every second and that
paper feed registration transfer puffer operation and development
lamp control will cycle, as previously described, once every
second. To illustrate this in the timing chart of FIG. 70
additional exposure events are illustrated by the reference letter
X once every second after the initial exposure. After the second
exposure approximately 2 seconds later or 1 second after the
energization of the feed clutch 512, the same will be actuated to
affect separation of a second sheet of paper from the paper stack
S. Similarly the "up" solenoid SOL-1 will be energized again 1
second after its first energization in order to insure proper
registration of the leading edge of the second sheet of paper prior
to its entering the transfer station.
It will be apparent that operation of the "down" solenoid SOL-2,
the commencement of the paper separation and transfer movement, the
commencement of the developed image transfer operation, and the
operation of the puffer solenoid SOL-4 will occur repeatedly with 1
second intervals. In this manner then, multiple copies of an
original will be produced until the machine is shutdown by the
energization of the shutdown relay 3CR either automatically after
the preset number of copies have been made or the machine is
shutdown by the operator say by closing the "Off" switch SW-2.
During multiple copy operation, the development control discharge
lamp LMP-5 will be energized to discharge the portion of the drum
moving past the lamp during those times that a latent image is not
traveling past this lamp. These times occur for the spaces between
copies and at the time that the trailing edge of the last copy has
moved past the lamp and before the belt drive is terminated which
occurs at shutdown condition of the machine. As shown in the timing
chart of FIG. 70, the discharge lamp is energized during a single
copy operation at a time when no latent image is present upon the
selenium belt and, for illustration is designated by the reference
letter Y.
As shown by the hatch marks, the discharge lamp will remain
energized during single copy operation until the machine assumes a
shutdown mode in order to completely discharge the charged areas of
the belt. During multiple copy operation however, the discharge
lamp will be energized only for short periods of time, those times
between the trailing edge of one latent image and the leading edge
of a succeeding latent image. These short periods of time would
occur once a second in the event that the machine is producing one
copy a second. In FIG. 70 the short periods of times are indicated
by the reference letter N. After the last copy of a multiple series
of copies have been made, the lamp will remain on until the
selenium belt drive terminates and the DC corotron supply is
de-energized.
During automatic operation when multiple copies are being produced,
the paper tray 400 in the paper handling mechanism 18 continues to
rise as paper sheets are fed off the stack. Upward movement on the
top of the paper stack during this normal continuous paper feed
operation is accomplished by the action of the switches SW-3, SW-4
which control the paper level to within a few sheet thicknesses. At
its upper limit, the control arm 496 will be rocked about the axis
of the shaft 513 by the upward movement of the separation rollers
485, 486 and this will cause opening of the normally closed switch
SW-4 for de-energizing the motor M-2. As the paper level drops
below a predetermined level, the arm 496 is rocked in the other
direction to cause closing of the normally open switch SW-3 to
energize the motor M-2 and effect raising of the paper tray and,
consequently the paper level. In effect, the switches SW-3, SW-4
provide the differential, measured in a few thicknesses of paper
sheets that determine the lower and upper limits, respectively, of
the paper stack level.
When the supply paper has been depleted, a "low" paper level
condition as far as the circuit for the switches SW-3, SW-4 is
concerned, the tendency would be to maintain energization of the
elevator motor. This prospect would cause damage to the structure
of the paper handling mechanism. In order to avoid this prospect,
the switch SW-8 is arranged to override the "low" level condition,
to cause reverse energization of the motor M-2 regardless of the
apparent closed circuit arrangement that would produce tray up
movement effected by the closed "up" switch SW-4 when the paper
level is low and, to produce de-energization of the shutdown relay
3CR for placing the machine in "Standby" condition. This reverse
energization of the motor M-2 will cause the paper tray to revert
to its lowermost position and in condition to accept more
paper.
As shown in FIG. 67 the circuit for the switches SW-3, SW-4 also
includes a manually operable switch SW-9 which may be mounted on
the console for the machine. This switch is arranged to cause
energization of the motor M-2 to produce up movement of the paper
tray in the event the operator desires to accomplish this movement
at the console or the switches SW-3, SW-4 have been disassociated
from the paper control arm 496. This control of the motor can also
be overridden by the switch SW-8 in the event the operator fails to
release the manual switch with no paper in the paper tray. Again,
upon activation of the switch SW-8, the tray is immediately lowered
and the machine reverts to shutdown condition. If there is paper in
the paper tray, the switch SW-4 will produce de-energization of the
motor M-2 and the tray will be in paper feed position.
Similarly, there is provided another manually operated switch SW-10
for controlling the elevator motor for causing the same to drive
the paper tray to its lowermost point. Actuating this switch
energizes the elevator motor to lower the tray until the same
reaches its lowermost position whereupon the lower limit switch
SW-7 will be actuated to open the circuit to the motor. Actuation
of the switch SW-7 occurs the, to override either the manual switch
SW-10 or the normal mode of automatic operation which occurs when
the upper limit switch SW-8 is activated, as previously
described.
Throughout operation of the machine whether in the single copy mode
or the multiple copy mode, the tracking of the selenium belt is
under the control of the reversible motor M-11. A suitable belt
edge sensing finger for a potentiometer POT and its associated
circuitry BT may be arranged to control the energization of the
motor and its direction of rotation.
While there is in this application specifically described one form
which the invention may assume in practice, it will be understood
that this form of the same is shown for purposes of illustration,
and that the invention may be modified and embodied in various
other forms without departing from the scope of the appended
claims.
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