U.S. patent number 3,689,146 [Application Number 05/033,219] was granted by the patent office on 1972-09-05 for electrophotographic copying machine.
This patent grant is currently assigned to Canon Kabushiki Kaisha, Tokyo, JP. Invention is credited to Hajime Katayama, Masaru Yamaguchi, Yoshio Ito.
United States Patent |
3,689,146 |
|
September 5, 1972 |
**Please see images for:
( Certificate of Correction ) ** |
ELECTROPHOTOGRAPHIC COPYING MACHINE
Abstract
An electrophotographic copier comprises a photosensitive drum
including a photoconductive layer and an outer insulative layer.
Apparatus for forming and developing an image of an original on the
drum surface is selectively supported peripherally thereof as is
apparatus for feeding copy material to the drum surface, for
transferring developed images to the copy paper and for cleaning
the drum surface. The developing, image transfer, fixing, cleaning,
and copy separating devices are supported on a single unitary
support member which is manually movable into and out of the
operative position adjacent to the drum surface. A carrier for
supporting the original is arranged for reciprocating movement with
respect to the drum. Preferred embodiments of such peripherally
supported apparatus are also disclosed.
Inventors: |
Yoshio Ito (Tokyo, JP),
Hajime Katayama (Kawasaki, JP), Masaru Yamaguchi (Tokyo,
JP) |
Assignee: |
Canon Kabushiki Kaisha, Tokyo,
JP (N/A)
|
Family
ID: |
26373552 |
Appl.
No.: |
05/033,219 |
Filed: |
April 30, 1970 |
Foreign Application Priority Data
|
|
|
|
|
May 2, 1969 [JP] |
|
|
44/34714 |
Aug 12, 1969 [JP] |
|
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44/63653 |
|
Current U.S.
Class: |
399/110; 399/119;
399/335 |
Current CPC
Class: |
G03G
21/1647 (20130101); G03G 2221/1654 (20130101); G03G
2221/16 (20130101); G03G 2221/163 (20130101); G03G
2221/1657 (20130101); G03G 2221/1618 (20130101) |
Current International
Class: |
G03G
21/16 (20060101); G03g 015/00 () |
Field of
Search: |
;355/3,8,13,14,50,65,66 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: John M. Horan
Assistant Examiner: Kenneth C. Hutchison
Attorney, Agent or Firm: Watson, Leavenworth &
Kelton
Claims
What is claimed is:
1. An electrophotographic copier comprising a housing, a shaft
supported in said housing, a carrier adapted to receive an original
to be reproduced, a photosensitive drum supported for rotation on
said shaft, means for projecting a light image of said original
onto the surface of said drum, means for developing electrostatic
images formed on said drum surface, means for feeding copy material
to said drum, means for transferring said developed electrostatic
images to said copy material, means for mixing said transferred
images on said copy material and means for cleaning said drum
surface, support apparatus for supporting each of said means
peripherally of said drum surface, said support apparatus including
a unitary support member supporting each of said developing means,
said transfer means, said fixing means and said cleaning means and
operator-controllable to position each said supported means in
operative position relative to said drum surface or in inoperative
position remote from said drum surface.
2. The copier claimed in claim 1 wherein said carrier comprises a
frame supported by said housing for said reciprocating movement, a
transparent member in said frame for supporting said original,
support arms pivotally supported by said frame and a pressure plate
member pivotally supported by said arms for movement into overlying
relation with said transparent member.
3. The copier claimed in claim 1 wherein said projecting means
comprises a lamp supported in said housing for illuminating said
original and thereby providing said original light image, a first
mirror for directing said light image away from said drum surface,
means for redirecting said light image onto said drum surface and
slit exposure means disposed intermediate said image redirecting
means and said drum surface, said image redirecting means including
a second mirror and a lens having two symmetrical sections.
4. The copier claimed in claim 1 wherein said feeding means
includes signal generator means rendered operative on each feeding
of copy material to said drum, said developing means being
operatively responsive to said signal generator means.
5. The copier claimed in claim 4 wherein said developing means
includes a container for developer toner and carrier, a condensed
toner supplier and means responsive to said signal generator means
for rendering said supplier operative to supply condensed toner to
said container.
6. The copier claimed in claim 1 wherein said photosensitive drum
comprises a cylindrical base, a photoconductive layer overlying
said base, an insulative layer overlying said photoconductive layer
and first and second retaining members respectively secured to
opposed ends of said base, said retaining members each having a
diameter substantially equal to that of said drum.
7. The copier claimed in claim 1 further including means for
separating copy material from said drum, said unitary support
member supporting each of said developing means, said transfer
means, said separating means, said fixing means and said cleaning
means and operator-controllable to position each said supported
means in operative position relative to said drum surface or in
inoperative position remote from said drum surface.
8. The copier claimed in claim 1 wherein said transfer means
includes a roller disposed in pressure contact with said drum
surface, a strip member intervening opposed marginal portions of
said roller and drum, said copy material feeding means
incorporating means for positioning a marginal part of each fed
copy material intermediate said strip member and said marginal
roller portion and for positioning the remaining part of each fed
copy material intermediate said roller and said drum.
9. The copier claimed in claim 1 wherein said fixing means
comprises a copy material inlet, a copy material outlet, a pair of
rollers supported intermediate said inlet and said outlet, a
conveyor encircling said rollers and supported for movement
thereby, electrode discharge means for applying charge to said
conveyor, and means disposed adjacent said conveyor for heating
copy material thereby conveyed.
10. The copier claimed in claim 9 wherein said fixing means
includes air ducting means having an exhaust port disposed adjacent
said inlet for ducting air heated by said heating means against
said conveyor.
11. The copier claimed in claim 9 wherein said support means
includes a unitary support element for detachably securing said
belt, said rollers and said heating means to said housing.
Description
The present invention relates to an improved electrophotographic
copying machine and more particularly to an electrophotographic
copying machine in which a photosensitive member having a
photoconductive layer interposed between a surface insulating layer
and a conductive or insulating member is employed so that in image
of a sheet-like original or an original having a relatively greater
thickness may be automatically, quickly and economically formed
upon an image recording medium such as ordinary paper.
Electrophotographic copying machines for reproducing copies of a
sheet-like original as well as an original having a relatively
greater thickness are divided into two types, one type employing
photosensitive papers and the other type employing no
photosensitive paper, that is, the so-called Xerographic type. In
the former type photosensitive papers are used so that cost is
considerably more than with ordinary paper. In the latter type,
inexpensive ordinary paper is used as an image recording medium,
but since a photosensitive drum having a photosensitive layer
formed by vacuum deposition of selenium is used, the surface of the
photosensitive layer tends to be directly mechanically damaged in
repetitive use of the drum. Thus, there is a problem regarding
durability of the drum with resultant increased cost. Mechanically,
the original is held in stationary position while the optical
system as well as the photosensitive drum inside the machine are
driven in synchronism with each other so that the copying machine
must have a highly precise mechanism which is inevitably large in
size.
Therefore, one of the objects of the present invention is to
provide an improved electrophotographic copying machine compact in
size, capable of high speed copying operation, especially capable
of reducing the copying or reproduction time required for
reproducing a single copy, simple in operation, and inexpensive to
manufacture. This object may be attained by employing the above
described photosensitive body coated with an insulating layer of a
polyester resin having considerable mechanical durability, for
example Mylar (Trade Name) and by using as an image recording
medium an ordinary paper or the like, so as to reproduce copies
from a sheet-like original or an original having a relatively
greater thickness which is moved during exposure.
Another object of the present invention is to provide an improved
electrophotographic copying machine having a mechanism for
separating, from a photosensitive drum, copy paper which is
electrostatically attracted thereto.
A feature of the present invention is to provide an improved
electrophotographic copying machine having fixing means for fusing
and fixing to a copy paper a powder image consisting of
thermoplastic resinous toner, said fixing means having a conveyor
belt for electrostatically attracting the copy paper thereto and
preheating the conveyor belt by air heated by heating elements,
which directly heat the conveyor belt, at a position at which the
copy paper is loaded upon the conveyor belt, thereby preventing the
copy paper from being curled.
According to one aspect of the present invention, an original
carrier is disposed at the top of the housing of the
electrophotographic copying machine. The original carrier is
provided with a pressure plate for holding in stationary position a
sheet-like original or an original having a relatively greater
thickness. A photosensitive body has a photoconductive layer
interposed between a surface insulating layer and a conductive or
insulating member. The photosensitive body is disposed around the
peripheral surface of a rotary drum, thereby providing a
photosensitive drum. The drum is rotated in one direction and first
charging means, contemporaneous exposure-corona-discharge means,
whole-surface-illuminating means, developing means, third charging
means, image transfer means, and cleaning means are disposed, in
the order named, peripherally of the photosensitive drum. (These
means will be referred to as "peripheral means" as a whole
hereinafter.) The drum is uniformly charged with positive or
negative charge by the first charging means, exposed to the light
image of an original to be reproduced contemporaneously with
application to the drum of a DC charge of polarity opposite to that
of the first charging or with AC charge (to be referred to as
"second charging"), and uniformly illuminated by the whole-surface
illuminating means. An electrostatic latent image so formed is
developed into a positive or negative image with toner. If
required, a third charging is made before the image is transferred
to a copy paper. In this case, the copy paper is electrostatically
attracted by the photosensitive drum so that it is separated by a
novel and useful separating means in accordance with the present
invention. The image transferred to the copy paper is fixed to the
copy paper.
The present invention will become more apparent from the following
description of the preferred embodiment thereof taken in
conjunction with the accompanying drawings in which:
FIG. 1 is a perspective view of one preferred embodiment of the
present invention;
FIG. 2 is a longitudinal sectional view thereof;
FIG. 3 is a sectional view, on enlarged scale, of a photosensitive
drum and an original carrier therefor,
FIG. 4 is a longitudinal sectional view of the original
carrier;
FIG. 5 is a front view illustrating the gear train for driving the
photosensitive drum;
FIG. 6 is a perspective view of the original carrier and its
reciprocating drive mechanism;
FIG. 7 is a detailed view of an exposure means;
FIG. 8 is a transverse sectional view of developing means;
FIGS. 9(1) and 9(2) and FIG. 10 are detailed views of a developing
agent supply device;
FIGS. 11(1) and 11(2) are detailed views of copy paper feeding
means;
FIGS. 12(1) and 12(2) are perspective views illustrating image
transfer means and copy paper separating means;
FIG. 13 is a longitudinal sectional view including an illustration
of fixing means in accordance with the present invention;
FIG. 14 is a side view of a mechanism for moving toward and away
from the photosensitive drum, an image transfer roller, the
cleaning means, the developing means and other means in unison with
each other; and
FIG. 15 is a perspective view thereof.
FIG. 1 is a perspective view of an electrophotographic apparatus in
accordance with the present invention. An original carrier 11 is
mounted upon the top of the housing and an original is placed upon
the original carrier 11 with its pattern to be reproduced facing
downwardly. The original carrier 11 is reciprocated. The copies
reproduced are discharged from an outlet to a tray 12. Copy paper
sheets P are fed one by one from a feeding station 55.
FIG. 2 is a longitudinal sectional view of the apparatus. A rotary
drum 2 has a photosensitive member 3 comprising a photoconductive
layer interposed between an outermost insulating (insulative) layer
and a conductive or insulating layer whereby a photosensitive drum
1 is constructed. The photosensitive drum 1 rotates in the
direction indicated by the arrow and a first charging means 4,
contemporaneous exposure-corona-discharge means 5, means 6 for
exposing the whole surface of the photosensitive drum 1, developing
means 7, third charging means 8, means 9 for transferring an image
from the photosensitive drum to a copy paper and cleaning means 10
are disposed around the periphery of the photosensitive drum 1 in
the order named.
The photosensitive member 3 upon the drum 1 is charged with
positive or negative charge by DC corona discharge by the first
charging means 4. By the contemporaneous exposure-corona-discharge
means 5, the photosensitive member 3 receives DC corona discharge
of polarity opposite to that of the first charge or AC corona
discharge (which will be referred to as second charging
contemporaneously with projection of a light or radiation image of
the pattern of an original to be reproduced upon the photosensitive
drum 1, thereby forming an electrostatic latent image.
Next, the electrostatic latent image thus formed upon the
photosensitive member 3 is uniformly irradiated by the
whole-surface illumination means 6, such as a fluorescent lamp, so
that the field of the electrostatic latent image external to the
drum is intensified, thereby forming upon the surface of the
photosensitive drum 1 an electrostatic latent image having high
contrast. The latent image thus obtained is developed into a
visible image by developing means 7 with toner charged oppositely
to the polarity of the electrostatic latent image or with the toner
having the same polarity as that of the latent image. Preferably,
the magnetic brush method or the fur brush method is used. The
third charging means 8 is not necessarily required, but it may be
advantageously used with a suitable polarity in order to improve
efficiency in transferring the powder image upon the photosensitive
member 3 to an image recording medium (which is generally a paper
sheet and will be referred to as "copy paper" hereinafter). The
powder image is transferred electrostatically to the copy paper P
by the image transfer means 9. The toner still remaining upon the
photosensitive drum 1 is removed by the cleaning means 10, such as
a roller.
The copy paper P bearing thereupon the powder image transferred
from the photosensitive drum is separated from the drum 1 and the
transferred image is fixed by the fixing means. The copy paper
bearing the fixed image is discharged through an outlet.
The apparatus in accordance with the present invention includes the
above described electrophotographic processing station, the
original carrier, drive means for driving the original carrier,
exposure means, copy paper feeding means, image transfer and copy
paper separation means, fixing means, an operational control
system, etc. the arrangement of which characterizes the present
invention. The above described means and system will be described
in more detail hereinafter.
ORIGINAL CARRIER AND DRIVE MECHANISM
As shown in FIG. 3, the original carrier 11 runs horizontally upon
an angle rail 13 and a round rail 14 laid between the frames of the
main body through a roller 17 and a hand-drum-shaped roller 18
which are rotatably fixed to the channels 16.sub.1 and 16.sub.2
(See FIG. 6) which in turn are securely fixed to the side edges of
the under-surface of the inner frame 15 of the original carrier 3.
The lateral vibrations of the original carrier 3 are received by
the roller 18 and the rail 14 while the vertical vibrations are
damped or absorbed by springs 20 through the roller 19 which is
vertically movably supported in the channel 16.sub.2 and is placed
in contact with the lower side of the rail 14.
As shown in FIG. 4, a transparent original supporting glass 21 is
placed upon the inner frame 15 of the original carrier 3 and an
original holder 22 is provided for closely pressing the original M
against the original supporting glass 21. The original holder 22
comprises an arm 51 pivotably fixed at 50 to the inner frame 15 for
rotation in a plane perpendicular to the original carrier, a
retaining member 54 U-shaped in cross section and pivotably fixed
by a pin 52 to the arm 51 and a rubber sheet 53 fixedly retained by
the retaining member 54. The original holder 22 may be raised
depending upon the thickness of the original M as shown by broken
lines in FIG. 4 so that even a thick original M may be pressed
against the glass 21 in a satisfactory manner without necessity to
substantially increase the length of the rubber sheet 52.
A rotary shaft 26 of the photosensitive drum 1 is journaled by
bearings 23 which are securely fixed to the side plates 1.sub.1 and
1.sub.2 of the drum 1 and by a drum supporting member 25 which in
turn is securely fixed to the bottom plate 24 of the housing. A
drum drive gear G4 is carried by the drum shaft 26 through the
bearing 23. The drum side plate 1.sub.2 is provided with an
outwardly extending projection 27 which is fitted into a recess 28
formed in the boss of the gear G4, so that the drum 1 may be
mounted upon and detached from the shaft 26 by sliding the former
relative to the latter. The drive gear G4 has a control cam 33 (see
FIG. 5) formed integrally therewith so as to control switches MS-4
to MS-8, which constitute a control unit. The end remote from the
drive gear G4 of the drum shaft 26 is journaled in an auxiliary
side plate 29 which is detachably fixed to the bottom plate 24 so
that the drum 1 may be readily mounted and detached.
The drum 1 is rotated in one direction by a main motor MT fixed to
the drum supporting member 25, through a gear G1, idlers G2 and G3
and the drive gear G4 carried by the drum shaft 26. In exposure,
the original carrier 11 is displaced in the direction indicated by
the arrow a in FIG. 2 and upon completion of the exposure, the
carrier 11 is reversed in the direction indicated by the arrow b
and returned to its initial or normal position. As shown in FIG. 6,
two belts or wires 30 and 31, each having an end secured to the
channel 16.sub.2 fixed to the undersurface of the original carrier
11, are wrapped in opposite directions around the guide pulleys
30.sub.1 and 31.sub.1 and around an original carrier drive pulley
30p carried by the drum shaft 26, and then the other ends of the
belts or wires 30 and 31 are securely fixed to the pulley 30p. The
drive pulley 30p is rotated in forward and reverse directions in
one cycle of the copying operation, through two clutches C-1 and
C-2 as shown in FIG. 5. In one undirectional or forward stroke of
the original carrier 11, the clutch C-2 is actuated so that the
driving force from the motor MT is transmitted to the drive pulley
30p integral with the gear G7 through the gears G1, G2, G3, G4 and
G5, the clutch C-1 and the gears G6 and G7, so that the drive
pulley 30p is rotated in the direction indicated by the arrow in
FIG. 6. Therefore, the wire 30 is wound around the drive pulley 30p
so that the original carrier 11 is driven in the direction
indicated by the arrow a at a predetermined velocity, whereby the
original M (See FIG. 4) is exposed through a slit. That is, the
light image of the original is projected upon the drum 1 through
the contemporaneous exposure-corona discharge means 5 so that an
electrostatic latent image is formed upon the photosensitive drum 1
which is previously charged by the first charging means 4.
It is to be noted that in the case of the reproduction of copy at a
magnification of unity, the peripheral velocity of the drum 1 is
equal to the velocity of the original carrier 11 in the forward
stroke. When the original carrier 11 reaches the end of the forward
stroke, a stroke cam 32 (See FIGS. 3 and 6) fixed to the channel
16.sub.2 of the original carrier 11 actuates a micro-switch MS-1
which is securely fixed to the left end of the frame of the main
body so that the clutch C-2 is activated while the clutch C-1 is
deactivated. Thus, the drum 1 continues to rotate in the same
direction while the drive pulley 30p is reversed in rotation so
that the original carrier 11 is returned to the initial position in
the direction b. It is seen that the original carrier 11 may be
quickly returned to the initial position by suitably determining
the ratio of the number of teeth of the gear G6 for the forward
stroke to that of the gear G8 for the return stroke, both of which
gears are selectively engaged with the gear G7. Thus, the copying
operation can be made at a high speed.
Upon returning of the original carrier 11 to the initial position
(at the right end), the stroke cam 32 actuates a microswitch MS-2
(See FIG. 6) fixed to the right end position of the main body so
that the main motor MT is temporarily retarded whereby the original
carrier is braked. After a suitable time delay, the microswitch
MS-3 is deactivated, so that the clutch C-2 for the return stroke
is de-energized, thereby precisely returning the original carrier
11 to the initial position and disconnecting the carrier from its
drive mechanism.
On the other hand, the drum 1 is temporarily braked and stopped but
the brake is released after a very short time (a few to tens of
microseconds), so that even when the original carrier 11 is
stopped, the drum 1 continues its rotation and is finally stopped
when the home position cam 33 carried by the drum drive gear G4
deactivates the microswitch MS-4. The above two-step operation is
for absorbing the inertia of the original carrier in the return
stroke. For this purpose, the stroke of the original carrier 11 is
made relatively shorter than the whole stroke of the drum.
EXPOSURE MEANS
The illumination system 34 includes a light source for illuminating
the original such as a fluorescent lamp 35 with a reflector, a
light shielding plate 36 and a cooling fan (not shown) for cooling
the lamp 35 so as to prevent reduction in the intensity of light
emanating therefrom.
The cooling air is directed in the longitudinal direction of a
chamber defined by the shielding plate 36, the original carrier 11
and an optical unit (black box) 37 so that the lamps 35 are
effectively cooled over the whole length thereof. The current in
excess of a rated current is maintained in lamp 35 during exposure,
thereby increasing the intensity of illuminating light, but during
non exposure rated current flows through the lamp so that it is
always illuminated. Thus, there is no "waiting time" in printing
operations and the service life of the lamp 35 may be
increased.
The light from the lamps 35 illuminates the original supported upon
the original carrier 11 and light reflected from the original is
transmitted through a transparent, dust proof glass 39 which is
held in position upon the black box 37 by retaining members 38. The
reflected light is directed away from the drum as shown by a first
mirror 40 which is inclined at about 45.degree. relative to the
horizontal, to an in-mirror type lens 41. The in-mirror type lens
41 is a conventional lens divided into two sections along the axis
of symmetry and a mirror is positioned at the center. The light
reflected by a second mirror 41.sub.1 passes through the lens 41
again and is projected upon the drum 1 through the contemporaneous
exposure-corona discharge means 5 which is fixed to the black box
37 in opposed relation with the drum 1 and has an exposure slit in
the longitudinal direction.
The first reflecting mirror 40 is supported upon three embossed
projections of a mirror stand 44 and maintained in position by a
mirror pressure spring 43 which in turn is securely fixed to the
mirror stand 44. The mirror stand 44 is fixed to a stand (not
shown) which is only movable in the horizontal direction. A pin 45
is fixed to the mirror stand 44 at the extension of the optical
axis so that the mirror stand 44 may rotate about the pin 45. A
stopper pin 46 is extended from the center of a stand which in turn
is fixed to the carrier (not shown). This pin 46 is externally
threaded at 48 so that the pin 46 may be movable. The mirror stand
44 is so biased by a spring 47 that the mirror stand 44 is normally
in contact with the pin 46 so that the angle of the mirror relative
to the horizontal axis may be adjusted by moving the pin 46. The
adjustment of the parallelism relative to the drum 1 and the
optical length is made by displacing the carrier in the horizontal
direction. A transparent dust proof member 49 is fixed to the
optical unit (black box) 37 so as to completely seal the optical
unit 37. When a conductive member such as NESA glass is used as the
dust proof member, the charging efficiency of the contemporaneous
exposure-corona-discharge means 5 may be improved.
ELECTROPHOTOGRAPHIC PROCESSING STATION
The photosensitive drum 1 is started in response to the depression
of a start switch. As described hereinabove, the light image of the
original is projected upon the drum 1 simultaneously with charging
of the drum 1 by the contemporaneous exposure-corona discharge
means 5. Next the drum 1 is uniformly illuminated by light
emanating from the lamp 6, whereby an electrostatic latent image
having a high contrast may be formed upon the drum 1.
The developing means is of a box-shaped construction as shown in
FIG. 8 having side walls 101 and a bottom plate 100, and includes
two magnetic brushes 102 and 103 rotatably journaled between the
opposing side walls 101, two blades 104 and 105, and guide rails
108 and 109 upon which rests a hopper 111. Each of the magnetic
brushes 102 and 103 is a magnetic roller having a plurality of
alternately arranged different poles carried by a non-magnetic
shaft. It is to be noted that different poles of the magnetic
brushes 102 and 103 are opposed to each other.
A developing agent 110 consists of colored, finely divided powder
(toner) and finely divided iron powder (carrier). The toner and the
carrier are mixed uniformly by a pair of mixing rollers 106 and 107
and then moved toward the first magnetic roller 102 to raising the
mixture by the blades. Then the developing agent is attracted by
the first roll 102 and is transferred to the second roller 103 so
that the so-called magnetic brush uniform attraction of developing
agent occurs. When the leading portion of the magnetic brush having
less magnetic flux contacts the surface of the drum 1 bearing an
electrostatic latent image, the leading portion of the magnetic
brush is attracted electrostatically by the drum 1 and is finally
cut off, so that fog and other undesired stains are formed upon the
image. Therefore, in order to eliminate this defect, the blades 104
and 105 are provided for the magnetic brushes so that the brush in
excess of a predetermined height may be cut off. The magnetic
brushes are rotated in the directions shown in FIG. 8 and the hard
or bristle magnetic brush in the space defined intermediate the
brushes and the drum 1 is placed in sliding contact with the
surface of the drum 1, thereby developing the latent image into a
visible image.
The mixing roll 107 serves to uniformly mix the condensed
developing agent 112 dropped from the hopper 111 immediately above
the mixing roll 107, with the developing agent in the developing
means and to supply the developing agent toward the mixing roll
106. The hopper 111 is moved into and away from the developing
means along the rails and guide rails 108, 109 and 120 disposed
between the side walls 101 of the developing means. The hopper 111
has a U-shaped main body 113 and guide blocks 114 (See FIG. 10) at
both ends of the main body 113. The bottom 116 has a plurality of
openings 115 extending laterally and spaced apart from each other
in the longitudinal direction by a suitable distance. A moving
plate 117 having a plurality of openings 118 having the same
dimensions and pitch as those of the openings 115 is interposed
between the guide blocks upon the bottom 116 for slidable movement
in the longitudinal direction. (See FIG. 10). Normally the moving
plate 117 is so biased by a spring that the openings 118 of the
moving plate 117 will not register with the openings 115 of the
bottom 116. Therefore, only when the developing agent feed button
119 is depressed do the openings 115 register with the openings 118
so that the developing agent 112 is dropped into the developing
means. Hopper guide rails 120 are fixed to the lower side walls of
the main body 113 in such a manner that each lower free end 121 of
the guide rail 120 is bent inwardly (See FIG. 8). A control plate
122 for controlling the quantity of developing agent to be dropped
has openings or slits having the same dimensions and pitch as those
of the openings 116 and 118 and is interposed between the guide
plates 120 and the bottom 116 for slidable movement in the
longitudinal direction in order to control the quantity of the
developing agent to be dropped through the openings 115 of the
bottom 116. That is, the maximum quantity of developing agent is
dropped when the openings of the bottom 116, the moving plate 117
and the control plate 122 coincide with each other. The quantity of
the developing agent to be dropped is controlled by the control
plate 122.
FIGS. 9(1) and 9(2) illustrate a mechanism for automatically
depressing the hopper button 119 of the condensed developing agent
feeding hopper. A cam gear G22 is driven by a gear G20 carried by a
shaft 123 of the second roller 107 through a clutch gear G21. The
cam gear G22 makes one rotation in response to each feeding of a
copy paper. The projection 125 of a cam 124 made integral with the
gear G22 engages a counter lever 126 so that a counter ratchet
wheel 127 rotated by one tooth. That is, the counter ratchet wheel
127 advances by one tooth when each copy paper is fed. A projection
128 extends from one side face of the counter ratchet wheel 127 and
engages the clutch releasing lever 129 to push the clutch releasing
lever 129 and disengage the lever from a stepped portion 132 of a
clutch sleeve 130. Therefore, a spring 130.sub.1 loaded in the
sleeve 130 winds itself around the bosses of the clutch gear G21
and that of the hopper cam 130.sub.2 so that the gear G21 drives
the cam 130.sub.2 whereby the hopper button 119 is depressed by the
cam surface 130.sub.2. Thus, the openings 118 of the moving plate
117 coincide with those of the bottom 116 thereby supplying the
developing agent. The clutch releasing lever 129 actuated by the
counter ratchet wheel 127 may be immediately returned to its
initial position so that when the clutch sleeve 130 makes one
rotation, the leading end 131 of the clutch releasing lever 129
engages with the stepped portion 132 of the sleeve 130, thereby
stopping the sleeve 130. Then, the spring clutch is released and
the hopper cam is stopped. Unless the counter ratchet wheel 127 is
advanced by one tooth as one copy paper is fed so that the
projection or pin 128 actuates the clutch releasing lever 129, no
developing agent is supplied. The developing means 7 is activated
by a signal generated when the copy paper P passes over the
microswitch MS-9 between the feed rollers 58 and 59 (See FIG. 2) as
will be described in more detail hereinafter so that unless copy
paper is feed, reproduction is not commenced even when the machine
is driven, and no excessive developing agent 112 is supplied.
COPY PAPER FEEDING STATION
As shown in FIG. 2, the feeding station comprises copy paper
feeding means 55 and copy paper transporting means 56. The copy
papers in the feeding means 55 are fed toward the transporting
means 56 one by one by a feed roller 57 which rotates in response
to a signal from the control means 33 (See FIG. 5). The
transporting means comprises a first, second and third pairs of
rollers 58, 69 and 60. The first roller 58 is intermittently driven
in response to the signal from the control means 33 in order to
adjust the time when the image upon the drum 1 is transferred to
the copy paper P in the transfer means 9 and to ensure the
registration of the leading edge of the copy paper P with that of
the original M. The second and third feed rollers 59 and 60 are
normally driven so as to transport the copy paper P to the transfer
means 9. Since the first roller 58 is not driven when a copy paper
P is fed from the feeding means 55 by the feed roller 57, the copy
paper P is bowed as indicated by the broken line so that the
leading edge of the copy paper P is disposed parallel to the axis
of the first roller 58. In response to the signal from the control
means 33, the first roller 58 is driven so that the copy paper P is
transported by the second and third rollers 59 and 60 into the
image transfer means 9 in such a manner that the leading edge of
the copy paper P is registered with that of the powder image upon
the photosensitive drum 1. Thereafter, the powder image upon the
drum 1 is transferred to the copy paper P when the latter is
pressed against the drum 1 by a pressure or transfer roller 9.
The switch MS-9 is interposed between the first and second rollers
58 and 59 in the path of the copy paper so as to detect the passage
thereof, thereby controlling the developing means 7. When no copy
paper is transported so that the switch MS-9 is not actuated, the
developing means 7 is not activated. Therefore, the electrostatic
latent image formed upon the drum 1 will not be developed so that
the transfer roller 9 which is normally made in rolling contact
with the drum 1 is not stained. No load is applied to the cleaning
roller 61 in the cleaning means 10. The copy paper feeding means 55
will be described in more detail with reference to FIGS. 11(1) and
11(2). A copy paper stand 199 is detachably mounted through guide
rails or the like upon the main body of the photocopying machine. A
pair of L-shaped guides 200 and 201 are placed upon the stand 199.
The right guide 200 is securely fixed to the stand 199 while the
left guide 201 may be displaced on a slide pin 202 extending from
the undersurface of the left guide 201 and being movable in a guide
slot 203 formed in the stand 199 depending upon the sizes of the
copy papers. The rear portions of both of the guide plates 200 and
201 are cut away so as to form notches into which are fitted copy
paper pressure members 205 biased inwardly by springs 204. Thus,
the copy papers P are held in position with their side edges being
held by the pair of right and left guides 200 and 201 to eliminate
undesired resistance, and the separation of the copy papers P is
much facilitated.
Separating levers 207 and 208 are vertically pivotably fixed to the
outer side edges of the guides 200 and 201 by pins 206. At the
leading or free end of each of the separating levers 207 and 208 is
formed a separating pawl consisting of a vertically downwardly bent
portion 209 for preventing the displacement of the copy papers P
and a horizontal portion 210 for holding the corner of the paper
from above. The copy paper P advanced by the feed roller 57 is
stopped by the vertical portion 209 of the separating pawl, but the
center portion of the copy paper P is still advanced so that the
leading edge stopped by the separating pawl is buckled, whereby
only the uppermost copy paper is disengaged from the pawl and
advanced.
A stopper 240 is fixed to the leading end of the stand 199 by a pin
241 in such a manner that the stopper 240 may be normally held in
raised position by a spring (not shown). Thus, the stopper 240 may
be used as a reference in placing the copy papers upon the stand
199 because the pawls are not used since the separating levers 207
and 208 then lifted. A pawl releasing lever 213 for raising the
separating lever 208 is fixed to the stand 199 outwardly of the
movable guide 201 in such a manner that the lower end is extended
through the opening formed through the stand 199 and pivotably
fixed to the stand 199 by a pin 211. A cam 215 is also carried by
the pin 211 in such a manner that when the lever 213 is raised as
shown in FIG. 11(1) the cam 215 pushes the rear lower surface of
the lever 208 so as to raise it, thereby permitting the placing of
copy papers upon the stand 199.
Another cam 216 is also carried by the pin 211 so that when the
lever 213 is raised, pressure acts upon the plate spring 212
bridging the movable guide pins 202. That is, the pressure placed
upon the stand 199 from the movable guide 201 is released so that
the latter may be displaced. A shaft 222 extends over the stand 199
between bearing plates 223 and 224 securely fixed to the main body
of the photocopying machine outwardly of the stand 199. A tubular
shaft 225 is fitted over one half (the lower half in FIG. 11(2)) of
the shaft 222 and bearings 226 and 226.sub.1 are interposed between
the shaft 222 and the tubular shaft 225. A shaft 244 is journaled
in the leading ends of an arm 242 loosely fixed to the shaft 222
and another arm 243 securely fixed to the tubular shaft 225. The
copy paper feed rollers 57 are carried by this shaft 222. The
shafts 222 and 244 are drivingly coupled to each other by a chain
245.
A drive clutch gear G31 carried at one end of the shaft 222 is
meshed with a normally rotating gear G30 through a clutch C-5 in
response to a copy paper feed signal so that the rollers 57 are
rotated through the shaft 222, the sprocket wheels 246 and 247, the
chain 245 and the shaft 244. The gear G31 is driven by the chain
220 wrapped around a sprocket wheel 221.
As shown in FIG. 11(2), a boss 227 is securely fixed to the bearing
plate 224 coaxially with the shaft 225. A knob 299 is fitted into
the boss 227 and a spring 230 is loaded between the knob 229 and
the tubular shaft 225. The knob 229 is pulled out of the boss 227
against the spring 230 and rotated through an angle and held in
position by the engagement of a suitable projection and recess,
thereby pressing the feed rollers 57 against the copy papers
through the tubular shaft 225, the arm 243 and the shaft 244 by the
spring 230. The pressure acting upon the copy papers may be
adjusted by the knob 229, thereby ensuring the smooth feeding of
copy papers irrespective of the difference in quality.
As the copy papers upon the stand 199 are used, the positions of
the feed rollers 57 are gradually lowered so that the tubular shaft
225 is caused to rotate in the counterclockwise direction. This
rotation is detected by a cam 248 carried by the tubular shaft 225
and a microswitch MS-30 securely fixed to the bearing plate 224.
That is, the number of copy papers upon the stand 199 may be
detected so that when the number of copy papers becomes less than a
predetermined number, an alarm device such as a lamp in the control
panel is turned on.
IMAGE TRANSFER AND PAPER SEPARATING MEANS
The copy paper fed from the feeding means 55 and transported toward
the image transfer means by the rollers 58, 59 and 60 is pressed
against the powder image upon the drum 1 by the transfer roller 9.
Preferably the transfer roller 9 is made of an electrically
conductive material. Separating means generally designated by 300
is disposed in the image transfer means so that the copy paper may
be separated from the drum 1 after the powder image has been
transferred. That is, as shown in FIGS. 2 and 12, a copy paper
separating band 301 is extended forwardly and rearwardly of the
powder image transfer position, that is, the line of contact
between the transfer roller 9 and the drum 1, around the transfer
roller 9. For example, the separating band 301 is a polyester resin
film 50 .mu. in thickness and contacts one side or marginal edge of
the copy paper P over at least 10 mm.
The copy paper P is admitted into the nip between the drum 1 and
the transfer roller 9 from a guide 250 and one side edge of the
copy paper is disposed between the transfer roller 9 and the
separating band 301. After passing through the transfer position,
the copy paper is guided by the undersurface of the separating band
301 along the transfer roller 9 so that the copy paper may be
readily separated from the drum 1 and then fed into the fixing
means. The peripheral portion 9.sub.1 of the transfer roller 9,
around which is wrapped the separating band 301 (See FIG. 12(1)) is
made of a metal having a smooth surface and has a diameter slightly
smaller than that of the transfer roller 9, which is made of an
elastic material such as conductive rubber, so that the separating
band 301 is not placed in contact with the drum 1, thereby
preventing wear of the band 301. When the transfer roller 9 has a
stepped metallic roller member 9.sub.1, the application of a
potential to a conductive transfer roller or grounding thereof may
be facilitated. The separating band 301 has its both ends securely
fixed by retainers 303 and 304, but when the separating belt 301 is
so positioned around the transfer roller 9 that the belt 301 is not
made in contact with the photosensitive drum 1 as described
hereinabove, an endless belt may be used. The band 301 is given a
suitable tension by a tension pin 306 having a spring 307.
FIXING MEANS
The fixing means (FIGS. 2 and 13) comprises infrared lamps or
heaters 400, a blower 401 and a conveyor belt 402 which is advanced
in the direction indicated by the arrows. The blower 401 blows
heated air upon the copy paper P to which is transferred the powder
image from the drum 1 so that the powder image is fixed to the copy
paper P. The heated air from the blower 401 also ensures positive
holding of the copy paper upon the conveyor belt 402 spaced from
the heaters 400. The copy paper bearing the fixed image is
discharged out of the fixing means outlet 16 through a pair of
discharge rollers 403 and 404.
Now referring more particularly to FIG. 13 which illustrates one
embodiment of the fixing means in accordance with the present
invention, the conveyor belt 402 is wrapped around the drive roller
482 and a guide roller 483 between the transfer roller 9 and the
pair of discharge rollers 403 and 404 and the radiation heating
means 471 is disposed above the conveyor belt 402.
Preferably, the conveyor belt unit may be detachably mounted upon
the photocopying machine so that the inspection, repairs, etc. may
be facilitated. For this purpose, an opening 473, into which may be
fitted a side wall 472, is formed through the side wall 600 of the
main body of the machine. The conveyor belt unit may be guided by
guide rails 474. The conveyor belt 402 may be made of an
electrically insulating material having a resistance to heat, such
as tetrafluoroethylene containing glass fibers. A charging
electrode 475 and a grounding electrode 476 are disposed in the
path of the conveyor belt 402 so that charge may be imparted
thereto. The charge imparted to the conveyor belt 402 is the same
polarity as that of the charge imparted from the third charging
means 8. An insulating block 477 for enclosing therein the
electrode 475 is so disposed as to move in and out by a guide
477.sub.1 the bottom plate between the side walls 472 having heat
resisting material coated or lined upon the inner surface
thereof.
The radiation heater means 471 is supported between the side walls
600 by insulating material. In the instant embodiment, a pair of
reflectors 478 have mirror surfaces directed toward the conveyor
belt 402 and the heating elements 400 are disposed in the
reflectors 478 respectively. A duct 479 is formed behind the
reflectors 478 and incorporates therein the blower 401 so that the
air in a space defined between the reflectors 478 is sucked through
an opening 480 and blown against the copy paper P through an
opening 481 at the position where the copy paper P is loaded upon
the conveyor belt 402. A heat insulating chamber 484 is provided in
order to prevent the transmission of heat from the heating means
471 to the main body of the photocopying machine.
Since the conveyor belt 402 is imparted with the charge of the
polarity opposite to that given by the third charging means 8, by
the electrodes 475 and 476, the copy paper P loaded upon the
conveyor belt 402 is electrostatically attracted thereby during the
transportation. That is, when the polarity of the charge of the
powder image is negative while the polarity of the charge imparted
from the third charging means 8 is also negative, positive charge
is imparted to the copy paper P from the conductive transfer roller
9 which is grounded. Thus, the negative or positive charge, for
example, from 3 to 6 KV is imparted to the conveyor belt 402 by the
electrodes 475 and 476, thereby attracting the copy paper to the
belt 402. Since the heat insulating belt 402 is elevated to a
temperature of about 200.degree.C because it is always heated by
the heating means 471, the toner is fused and fixed upon the copy
paper P.
The copy paper P upon the conveyor belt 402 is heated not only by
the heaters in the reflectors in the radiation heating means 471,
but also by the heated air about 150.degree. to 200.degree.C from
the blower 401. As described hereinabove, the heated air around the
heaters is sucked by the blower 401 through the opening 480. That
is, the heated air flows upon the copy paper upon the belt 402 and
heats the copy paper. Thereafter, the heated air passes through the
duct 479 and is then blown through the opening 481 upon the copy
paper upon the belt 402. Therefore, the copy paper as well as the
powder image thereupon are preheated, thereby preventing curling of
the copy paper due to the sudden heating. The heated air from the
blower 401 serves to hold the copy paper upon the conveyor belt 402
which is also attracted electrostatically thereby. Since the heated
air is circulated, temperature variation may be prevented so that
the belt 402, heating means 471 and other parts may be maintained
at a uniform temperature and the thermal efficiency may be
improved. According to the present invention, the toner may be
fixed to the copy paper in a very effective manner by the direct
heating of the copy paper as described hereinabove. The toner is
prevented from directly contact the heating elements so that
complex means for preventing the offset described above is not
required. Furthermore, even though the copy paper is transported
upon the belt, no curling is produced, whereby jamming of copy
paper may be prevented.
CLEANING MEANS
The toner remaining upon the drum 1 even after the powder image is
transferred to the copy paper may be removed by the cleaning means
comprising a cleaning roller 61. The cleaning roller 61 comprises a
rotary shaft 500, a roller 501 made of an elastic material and a
cloth 502 wrapped around the roller 501. The cleaning roller 61 is
rotated in contact with the drum 1 in a direction of rotation
opposite to that of the drum 1. The toner attached to the cleaning
roller 61 is removed by a brush roller 505 having hard brushes 503
extending from a rotary shaft 504. The removed tonner is dropped
into a toner receiving box 506. A partition wall 507 in the box 506
is for preventing the dispersion of the toner from the box 506 to
the drum 1. Because of the auxiliary cleaner 508 (See FIG. 2)
comprising an elastic body covered with a cloth, even a very small
quantity of the toner still remaining upon the drum 1 after it is
cleaned by the cleaning roller 61 may be completely removed from
the drum. The auxiliary cleaning means 508 is detachably mounted so
as to be replaced at a suitable time interval.
OTHER MEANS AND MECHANISMS
Since the drum 1 is cleaned by the cleaning means each time one
copy is reproduced in the manner described hereinabove, it is
necessary to prevent relative deviation and separation of the
photosensitive member 3 from the supporting drum 2 due to the
pressure applied to the drum 1 by the cleaning roller 61. That is,
the photosensitive member 3 must be securely held upon the
supporting drum 2. In order to clean all over the peripheral
surface of the photosensitive drum 1, the width of the cleaning
roller 61 (in the axial direction) must be longer than that of the
drum 1, so that the stronger pressure tends to act upon the side
edges of the drum, thereby causing the damage thereto. In order to
prevent this, photosensitive member retaining elements 13 (see FIG.
3) having an outer diameter equal to that of the drum 1 are
attached to the latter so as to protect the photosensitive member
3, to improve the durability of the drum 1 and to reduce the cost.
To remove or detach the drum 1, the auxiliary bearing plate 29 is
detached from the bottom plate 24 and then the drum 1 is displaced
toward the left in FIG. 3, thereby pulling it out of the shaft
26.
This is necessary for inspection and repair of the various means
disposed around the periphery of the drum 1 and for replacement
thereof. Thus, it is required that the transfer roller 9, the
cleaning roller 502, the developing means 7 and so on must be moved
away from the drum 1. Extensive time is required to separately move
away from the drum 1 each of the above means and the relative
positions of these means will be deviated when they are returned to
their normal operative positions. Thus, overall adjustment of the
photocopying machine would then be required with resultant time
loss, and a complex, tedious operation.
In order to eliminate this, the present invention contemplates
arranging these means around the periphery of the drum so as to be
moved toward and away from the drum 1 in unison by a link
mechanism. As shown in FIGS. 14 and 15, the transfer means 9, the
fixing means and the cleaning means are all carried by a common
supporting frame 600 while the developing means is carried by a
supporting member 602.
In order to move toward and away from the drum 1 these peripheral
means, a lever handle 603 is provided. When the lever handle 603 is
moved toward the position indicated by the broken lines in FIGS. 14
and 15, a shaft 604 and a guide plate 611 are rotated in the
counterclockwise direction. In the guide plate 611 is formed a
guide slot 612 in such a manner that the guide slot 612 may
approach the shaft 604 as the guide plate 611 is rotated, in the
clockwise direction. A pin 614 of an L-shaped lever 613 is fitted
into the slot 612 so that the lever 613 rotates about its pin 616
as the guide plate 611 is rotated. A pin 618 of a link 617 is
fitted into an elongated slot formed in the forward portion of the
lever 613 so that the link 617 lifts a lateral shaft 624 thereby
rotating levers 622 about a shaft 621 in the counterclockwise
direction. Therefore, a lateral bar 627 and the supporting frames
600 securely fixed thereto at both ends thereof are moved in the
direction indicated by the arrow d in FIGS. 14 and 15 since the
shaft 625 is connected to the lateral rod 627 through a ring 623, a
link 626 and a ring 601. Thus, the transfer roller 9, the fixing
means and the cleaning means carried by the supporting plates 600
are moved away in unison from the drum 1.
When the lever 622 and the lateral rod 625 are rotated in the
counterclockwise direction, the links 605 connected to the lateral
rod 625 are rotated about the shaft 604 in the counterclockwise
direction while being guided along the elongated slots 607 so that
the lever 629 carried by the shaft 628 is rotated in the clockwise
direction through the lateral rod 603, thereby moving the
developing means supporting member 602 in the direction indicated
by the arrow c.
It is therefore seen that all of the peripheral means around the
drum 1 are moved away therefrom, whereby the drum 1 may be readily
detached. Upon returning to the initial position of the lever
handle 603, the above described operations are reversed so that all
of the peripheral means may be precisely returned to their normal
positions relative to the drum 1.
From the foregoing, it is seen that the electrophotographic copying
machine in accordance with the present invention is compact in size
because the first charging means, the contemporaneous
exposure-second charging means, the whole surface illumination
means, the developing means, the third charging means if required,
the image transfer means and the cleaning means, all of which are
required for electrophotographic processing, are disposed around
the drum; the original carrier is disposed above the drum for
reciprocal movement; the optical exposure means and the cleaning
means are disposed laterally of the original carrier; and the copy
paper feeding means, the transfer means and the fixing means are
disposed downwardly of the drum.
The optical system is disposed upwardly of the developing means but
laterally of the drum and is sealed by an optical unit so that the
lens, mirrors, etc. of the optical system may be completely
prevented from being contaminated or stained by the toner, dust and
so on. The copy paper separating band is interposed between the
transfer roller and the drum so as to guide the copy paper awaY
from the drum along the separating band, thereby smoothly and
positively separating the copy paper from the drum.
The drum is rotatably carried by the main shaft and is drivingly
coupled to the drive means through the coupling means disposed at
one end of the drum. The cleaning means and the transfer means are
supported by the common supporting members so that these means may
be moved toward and away from the drum by operating the lever
handle, whereby the mounting and detachment of the drum is much
facilitated and peripheral means around the drum may be inspected,
repaired, and lubricated in a very simple yet positive manner.
* * * * *