U.S. patent number 3,717,409 [Application Number 05/133,022] was granted by the patent office on 1973-02-20 for cleaning of electrostatographic surfaces.
This patent grant is currently assigned to Xerox Corporation. Invention is credited to Wilbur G. Hespenheide.
United States Patent |
3,717,409 |
Hespenheide |
February 20, 1973 |
CLEANING OF ELECTROSTATOGRAPHIC SURFACES
Abstract
An inflated elastic tube is maintained in pressure contact with
a moving electrostatographic recording surface having residual
toner thereon whereby a ridge of toner is accumulated on the
recording surface. The contact between the inflated tube and the
recording surface is periodically interrupted; e.g., by deflating
the tube or moving the tube away from the surface, and the
accumulated toner is carried by the recording surface into the
development apparatus.
Inventors: |
Hespenheide; Wilbur G. (West
Lake Village, CA) |
Assignee: |
Xerox Corporation (Stamford,
CT)
|
Family
ID: |
22456661 |
Appl.
No.: |
05/133,022 |
Filed: |
April 12, 1971 |
Current U.S.
Class: |
399/359;
15/256.53; 15/1.51; 118/203 |
Current CPC
Class: |
G03G
21/0011 (20130101); G03G 21/0005 (20130101) |
Current International
Class: |
G03G
21/00 (20060101); C03g 015/22 () |
Field of
Search: |
;355/3,15
;118/104,203,261 ;15/256.51,256.53,1.5 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Matthews; Samuel S.
Assistant Examiner: Braun; Fred L.
Claims
What is claimed is:
1. An apparatus for cleaning an electrostatographic recording
surface, comprising:
an inflated elastic member; and support means for maintaining a
portion of the surface of the inflated member in contact with an
electrostatographic recording surface having particles on the
surface thereof to prevent particles on said recording surface from
moving past said member.
2. The apparatus as defined in claim 1 and further comprising:
means for periodically interrupting the contact between the surface
of the inflated member and the recording surface to permit
particles accumulated on the recording surface to move past the
elastic member.
3. The apparatus as defined in claim 2 wherein the means for
periodically interrupting the contact between said surface of the
inflated member and the recording surface comprises means connected
to the inflated elastic member to periodically inflate and deflate
said inflated elastic member to maintain and interrupt,
respectively, the contact.
4. The apparatus as defined in claim 2 wherein the means for
periodically interrupting contact between the inflated elastic
member and the recording surface comprises means connected to said
inflated elastic member to move said surface thereof into and out
of contact with said recording surface.
5. The apparatus as defined in claim 2 and further comprising means
to supply a dry solid lubricant to said recording surface.
6. The apparatus as defined in claim 2 wherein the support means
comprises:
a housing holding said inflated elastic member with said portion of
said surface of the elastic member extending beyond said
housing;
means pivotally supporting said housing; and
a resilient member positioned against said housing biassing said
housing toward the recording surface to maintain said portion of
said surface of the elastic member in contact with the recording
surface.
7. In an electrophotographic imaging apparatus including a movable
electrophotographic recording surface; a charging station to
provide an electrostatic charge on said recording surface; an
imaging station to provide an electrostatic latent image on said
recording surface; a development station for applying toner to said
recording surface to thereby render the electrostatic latent image
visible; a transfer station for transfering the toner image to a
support medium; a cleaning station for removing residual toner from
the recording surface; and means for moving the recording surface
past the charging station, imaging station, development station,
transfer station and cleaning station, the improvement
comprising:
said cleaning station including: an inflated elastic member;
and
support means maintaining a portion of the surface of the inflated
elastic member in contact with said recording surface to prevent
residual toner particles from moving past said inflated elastic
member.
8. The apparatus as defined in claim 7 and further comprising:
means for periodically interruption the contact between the surface
of the inflated member and the recording surface whereby particles
accumulated on the recording surface are moved by the recording
surface past the inflated elastic member to the development
station.
9. The apparatus as defined in claim 8 wherein the movable
electrophotographic recording surface is an annular surface on a
rotatable drum.
10. The apparatus as defined in claim 9 wherein the means for
periodically interrupting the contact between the surface of said
inflated member and the recording surface comprises means connected
to the inflated elastic member to periodically inflate and deflate
said inflated elastic member to maintain and interrupt,
respectively, the contact.
11. The apparatus as defined in claim 9 wherein the means for
periodically interrupting contact between the surface of the
inflated member and the recording surface comprises means connected
to said inflated elastic member to move said surface thereof into
and out of contact with said recording surface.
12. The apparatus as defined in claim 9 and further comprising
means to supply a dry solid lubricant to said recording
surface.
13. The apparatus as defined in claim 9 wherein said means for
interrupting contact between the surface of the inflated elastic
member and the recording surface comprises at least one groove
extending axially across said annular recording surface.
14. The apparatus as defined in claim 9 wherein the inflated
elastic member is in the form of a tube.
15. The apparatus as defined in claim 14 wherein the tube has a
diameter from about 0.5 inch to about 3 inches.
16. The apparatus as defined in claim 14 wherein the support means
for the elastic member comprises: a housing holding said inflated
elastic member with said portion of said surface of the elastic
member extending beyond said housing; means pivotally supporting
said housing; and a resilient member positioned against said
housing biassing said housing toward the recording surface to
maintain said portion of said surface of the elastic member in
contact with the recording surface.
17. In an imaging process wherein a movable electrostatographic
recording surface is moved past a charging station to provide an
electrostatic charge on said recording surface; an imaging station
to provide an electrostatic latent image on said recording surface,
a development station for applying toner to said recording surface
to thereby render the electrostatic latent image visible; a
transfer station for transferring the toner image from the
recording surface to a support medium, said recording surface
having residual toner thereon, the improvement comprising:
maintaining an inflated elastic member in contact with the movable
recording surface having the residual toner particles thereon to
prevent the particles from moving past the inflated elastic member
whereby the particles are accumulated on the recording surface;
and
periodically removing the accumulated toner particles from the
recording surface.
18. The process as defined in claim 17 wherein the accumulated
toner particles are periodically removed from the recording surface
by periodically interrupting contact between the inflated elastic
member and the recording surface and returning the accumulated
toner particles on the recording surface to the development
station.
19. The process as defined in claim 18 wherein said contacting is
periodically interrupted by inflating and deflating said elastic
member.
20. The process as defined in claim 18 wherein said contacting is
periodically interrupted by moving the inflated elastic member away
from the recording surface.
21. The process as defined in claim 18 and further comprising
applying a lubricant to the recoding surface to reduce the friction
between the inflated elastic member and the recording surface.
Description
BACKGROUND OF THE INVENTION
This invention relates to cleaning of particles from a surface and
more particularly to removing residual toner from an
electrostatographic recording surface.
The most common electrostatographic process is the
electrophotographic process, for example, as disclosed in U.S. Pat.
No. 2,297,691 to Carlson. As disclosed in the Carlson Patent, an
electrostatographic recording surface, comprising a photoconductive
insulating material on a conductive backing, is given a uniform
electric charge over its surface and is then exposed to the subject
matter to be reproduced, usually by conventional projection
techniques. This exposure discharges the charged areas in
accordance with the light intensity which reaches them and thereby
creates an electrostatic latent image on or in the photoconductive
material.
Development of the latent electrostatic image is usually effected
by an electrostatically attractable material, which is generally a
thermoplastic resin in the form of finely divided particles usually
in the size range from 1 to 30 microns, commonly referred to as
toner. In the development of the latent electrostatic image, the
toner is brought into surface contact with the latent electrostatic
image bearing surface and is held thereon electrostatically in a
pattern corresponding to the latent electrostatic image. The
developed image is then transferred to a suitable support material,
such as paper, and fused thereon to make a permanent image. In the
transfer step the resin material or toner is caused to adhere to
the support material to form the images thereon, but usually a
portion of the resin material or toner remains on the surface of
the photoconductive material.
The quantity of resin material or toner remaining on the
photoconductive surface will affect future operating steps of the
process, and if left remaining thereon has an accumulative effect
in that additional toner adheres more readily to the
photoconductive surface in both image and non-image areas
thereon.
The accumulated toner material is generally removed from the
photoconductive surface by the process disclosed in U.S. Pat. No.
2,751,616 to Turner. As disclosed in the Turner Patent, a rotating
brush mounted in a hood is rotated in surface contact with the
photoconductive surface to dislodge any residual toner adhering
thereto. The bristles of the brush are then contacted with a
flicking bar mounted in the hood to detach the particles of toner
adhering thereto. The hood in which the brush is mounted is in
fluid flow communication with a filter box having a filter mounted
therein through an exhaust duct, with the portion of the filter
box, downstream of the filter, being preferably connected to a
centrifugal blower to draw air from the hood which entrains the
toner particles removed from the brush by the flicking bar. The
toner particles are separated from the air as the air passes
through the filter.
The cleaning mechanism hereinabove described is complex and
occupies a significant portion of the overall space of the machine,
and in addition, requires an additional power source and drive
system. Furthermore, such a cleaning mechanism does not have any
provision for the recovery of the residual toner particles.
Moreover, the brush fibers must be replaced as a result of either
wear or an accumulation of toner particles on the brush fibers
which causes filming on the recording surface. In addition, the
rotating brush often throws toner particles into the environment
surrounding the brush housing resulting in unwanted toner deposits
in other areas of the machine. Accordingly, there is a continuing
need for new systems for cleaning reusable electrostatographic
recording surfaces.
SUMMARY OF THE INVENTION
Accordingly, an object of this invention is to provide for cleaning
of electrostatographic recording surfaces.
Another object of this invention is to provide for both the removal
and recovery of residual toner from electrostatographic recording
surfaces.
A further object of this invention is to provide for simple and
inexpensive cleaning of an electrostatographic recording
surface.
These and other objects of the invention should be more apparent
from reading the following description thereof with reference to
the accompanying drawings.
The objects of this invention are broadly accomplished by cleaning
an electrostatographic recoding surface by means of an inflated
elastic member which is held in contact with a moving
electrostatographic recoding surface containing residual particles,
whereby the particles are prevented from moving past the elastic
member and are accumulated on the recording surface. The
accumulated particles are periodically removed from the recording
surface, preferably by periodically interrupting the contact
between the inflated elastic member and the electrostatographic
recording surface whereby the accumulated particles are moved on
the recording surface past the cleaning station for subsequent
recovery.
The elastic member is formed of an abrasion resistant elastomeric
material such as polyurethane, natural rubber, neoprene, etc. which
does not adversely affect the recording surface; i.e., the material
does not affect the electrical characteristics of the recording
surface, and is preferably in the form of an inflatable elastic
tube which is of circular or other cross-section, with the tube
being inflated by the application of fluid pressure; either by
liquid pressure, such as water, or by gaseous pressure, such as
air. The diameter of the tubular member may vary over wide limits
from very small to very large diameters, but in general, the
tubular member has a diameter which ranges from about 0.5 inch to
about 3 inches, with the smaller diameter tubes generally requiring
a rigid backing member to maintain uniform pressure contact between
the inflated member and recording surface. The inflated elastic
member is maintained in contact with the recording surface by the
application of a uniform pressure thereto, with the applied
biassing pressure being sufficient to maintain such contact without
increasing the friction between the elastic member and recording
surface to a value at which the elastic member vibrates against the
recording surface, such vibration allowing particles to channel
under the elastic member. In general, the biassing pressure is less
than about 0.1 psig. The inflated elastic member functions as a
wiper which accumulates particles on the recording surface and is
extremely effective in that the inflated member can conform to the
irregularities on the surface without requiring high local
pressures.
The cleaning station of the present invention may also include
means for supplying a dry solid lubricant to the interface between
the inflated elastic member and the electrostatographic recording
surface to reduce the friction between the inflated member and the
recording surface and thereby enhance the ability of the elastic
member to maintain sealing contact with the recording surface. In
many cases, however, no lubricant is required for maintenance of
such sealing contact. The dry solid lubricant, if required, may be
supplied to the interface between the inflated member and the
imaging surface by various techniques. For example, the dry solid
lubricant may be in the form of a powder which is intimately mixed
with the toner and supplied to the surface of the imaging surface
during development of the latent electrostatic image.
Alternatively, the dry solid lubricant may be dispersed throughout
the photoconductive layer or suspended in a photoconductor
overcoating. As the surface of the overcoating or treated
photoconductor gradually wears away, additional dry lubricant which
was originally distributed through the photoconductive or
overcoating layer is exposed and made available at the interface of
the elastic member and imaging surface. In another alternative
embodiment, the dry solid lubricant may be sprinkled or smeared on
the imaging surface at any point during the imaging cycle prior to
the cleaning station. For example, a suitable dispenser such as a
plurality of dispensers described in U.S. Pat. No. 3,013,703 may be
positioned over an electrophotographic drum between the exposure
and development stations and adapted to continuously or
intermittently sprinkle dry solid lubricant particles on the
imaging surface. Any suitable dry solid lubricant may be employed.
Hydrophobic dry solid lubricants are preferred. Further, when the
lubricant may ultimately transfer to the receiving sheet, the
lubricant is preferably selected from the group of materials having
a color which matches the color of the receiving sheet, e.g., white
lubricant particles would be employed with white receiving sheets.
Obviously, contrasting colors may be employed for novel effects if
desired. Typical dry solid hydrophobic lubricants includes metal
salts of fatty acids such as zinc stearate, barium stearate, lead
stearate, iron stearate, nickel stearate, cobalt stearate, copper
stearate, strontium stearate, calcium stearate, cadmium stearate,
magnesium stearate, zinc oleate, manganese oleate, iron oleate,
cobalt oleate, copper oleate, lead oleate, magnesium oleate, zinc
palmitate, cobalt palmitate, copper palmitate, magnesium palmitate,
aluminum palmitate, calcium palmitate, lead caprylate, lead
caproate, zinc linoleate, cobalt linoleate, calcium linoleate, zinc
ricolinoleate and cadmium ricolinoleate; higher aliphatic acids
such as stearic acid and palmitic acid; and colloidal pyrogenic
silica particles such as Cab-O-Sil available from the Cabot
Corporation and mixture thereof.
Any suitable reuseable electrostatographic imaging surface may be
employed in the system of this invention. Well known
electrostatographic imaging surfaces include photoconductive
materials such as vitreous selenium, organic or inorganic
photoconductors embedded in a non-photoconductive matrix, organic
or inorganic photoconductors embedded in a photoconductive matrix
and the like. Representative patents in which photoconductive
materials are disclosed include U. S. Pat. No. 2,803,542 to
Ullrich, U. S. Pat. No. 2,970,906 to Bixby, U. S. Pat. No.
3,121,006 to Middleton, U. S. Pat. No. 3,121,007 to Middleton and
U. S. Pat. No. 3,151,982 to Corrsin. Generally, photoconductive
materials are supported by conductive substrates. Typical
conductive substrates include brass, aluminum, gold, platinum,
steel, glass coated with conductive oxides, metallized
non-conductive substrates, laminated sheets of metal and plastic
and the like. The conductive substrate may be in the form of a flat
plate, cylinder, flexible sheet or other suitable configuration.
Preferably, the photoconductive surface comprises vitreous
selenium, selenium alloys or mixtures of selenium and other
inorganic materials because superior copy quality is maintained for
a greater number of copying or duplicating cycles.
The cleaning system of this invention is particularly effective in
electrostatographic processes employing two-component type
developing materials comprising carrier and toner particles.
Representative patents in which these developer compositions are
disclosed include U. S. Pat. No. 2,618,551 to Walkup, U. S. Pat.
No. 2,618,552 to Wise, U. S. Pat. No. 2,633,415 to Walkup and Wise,
U. S. Pat. No. 2,659,670 to Copley, U. S. Pat. No. 2,788,288 to
Rheinfrank and Jones and U. S. Re. Pat. No. 25,136 to Carlson.
Generally, the toners have an average particle diameter between
about 1 and about 30 microns, and the relatively larger carrier
beads have an average particle diameter from about 30 to about
1,000 microns in diameter. Typical toner concentrations include a
range from about 0.5 to about 10 percent by weight based on the
total weight of the two-component developer composition.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic sectional view of an electrostatographic
reproducing apparatus incorporating an embodiment of the
invention.
FIG. 2 is a schematic sectional view of an electrostatographic
reproducing apparatus incorporating another embodiment of the
invention.
FIG. 3 is a schematic sectional view of an electrostatographic
reproducing apparatus incorporating a further embodiment of the
invention.
FIG. 4 is a schematic sectional view of an electrostatographic
reproducing apparatus incorporating yet another embodiment of the
invention.
DESCRIPTION OF EMBODIMENTS OF THE INVENTION
Referring to FIG. 1 of the drawings, there is illustrated an
electrostatographic machine employing an embodiment of this
invention. The machine includes an image forming member such as,
for example, an electrophotographic cylinder designated 10 and
generally including an insulating or photoconductive insulating
layer disposed on a conductive backing. The cylinder is rotatably
mounted on a suitable axle 11 or other bearing member and is
adapted to be rotated by drive means such as, for example, an
electric motor (not shown) or the like. Preferably the cylinder,
and in particular its conductive backing, is electrically grounded.
The image forming or image receiving surface of the
electrophotographic cylinder 10 is adapted to be rotated past
appropriate electrophotographic processing stations disposed and
positioned to form an electrostatic image on the cylinder surface.
For example, when used with a photoconductive insulating
electrophotographic image surface, the electrophotographic
processing stations may include means for charging or sensitizing,
exposure means, developing means and cleaning means. Illustrated in
the figure is a charging station generally designated 14 at which
is positioned a corona discharge electrode 15, desirably one or
more high voltage corona discharge wires 16 mounted within a
grounded shield 17 and adapted to be connected to a high voltage
source such as, for example, a positive polarity direct current
source of several thousand volts. In general the voltage applied to
the corona discharge electrode will be sufficient to cause air
ionization surrounding the corona wires and it is understood that
such a corona discharge potential is generally in the order of
several thousand volts and usually 5 to 10 thousand volts as
disclosed, for example, in Walkup U. S. Pat. No. 2,777,957.
Positioned next adjacent to the charging station is an exposure
station generally designated 18 and including suitable means for
projecting or otherwise directing a light or optical image onto the
surface of the electrophotographic drum. The exposure station may
include a slit projection mechanism for exposing onto the drum
surface a moving projected image of microfilm or the like, and may
include means for projecting onto the surface documentary or other
information or an image corresponding to the face of a cathode ray
tube of the like. As is disclosed in Carlson u. S. Pat. No.
2,297,691, the combination of electric field and exposure to
activating radiation forms on the drum surface an electrostatic
image capable of being developed or made visible by deposition of
finely divided charged particles.
A development station for developing the latent electrostatic
image, generally designated as 21, is positioned at a subsequent
location around the circumference of the drum. The development
station, as shown, includes a sump 22 containing a two component
developer material comprised of toner and carrier, for example of
the type disclosed in U. S. Pat. No. 2,618,551 to Walkup; a
conveyor 23, which is driven through suitable drive means by a
motor 24; and a chute 25 for transporting developer released from
the conveyor to the surface of the drum 10. In operation, the
conveyor 23 transports the developer from the sump 22 to the chute
25, and the developer released from the chute 25 cascades over the
surface of the drum 10, whereby the toner particles are attracted
to the image areas previously formed thereon to render the image
visible. The unused developer material which has cascaded over the
surface of the drum 10 falls into the sump 22, and the developer
material in the sump 22 is periodically provided with toner through
dispenser 26, e.g., of the type described in U. S. Pat. No.
3,013,703 to Hunt, to replenish the toner used to develop the
image.
Although the embodiment is described with reference to a cascade
development system, it is to be understood that the latent image
may be developed by any one of a wide variety of other development
techniques, such as, for example, fur brush development and the
like.
Positioned subsequently around the surface of the
electrophotographic drum is an image transfer station generally
designated 27 including for example a supply roll 28 of transfer
material such as, for example, a roll of paper and a take-up roll
29 together with guide means and the like to feed the image
transfer material into contiguous relationship with the
electrophotographic drum. As illustrated in the figure, suitable
guide rolls 30 may guide and optionally drive the transfer web into
contact with the electrophotographic drum, and transfer means such
as, for example, a corona discharge electrode 31 is positioned to
transfer the developer image to the image web at the transfer
station. Preferably, the transfer means in a corona discharge
electrode of substantially the same construction as is located at
the charging station 14 although other transfer means may be
employed such as the means disclosed in U. S. Pat. No. 2,807,233.
For the usual case of direct or positive-to-positive photographic
copy the charging electrode 15 and the transfer electrode 31 are of
the same polarity and for the opposite situation of photographic
reversal the electrodes are of opposite polarity. Optionally
positioned near the transfer station and along the line of travel
of the transfer web subsequent to the transfer station is a fusing
station generally designated 32 and including a plurality of
heating elements 33 suitably contained within a housing 34 and
adapted to fuse onto the web surface the image that has been
transferred thereto. It is understood that suitable vapor fixing
means may be employed as disclosed for example in Carlson U.S. Pat.
No. 2,776,907.
The recording surface of the drum 10 is then cleaned in cleaning
station 40 to complete the cycle which includes: charging,
exposure, development, transfer and cleaning.
The cleaning station 40 is comprised of an inflated elastic member
in the form of inflated elastic tubing 41 which is positioned
transverse to and coextensive with the recording surface of drum
10. The elastic tubing may be shaped other than as shown; for
example, the tubing may have a smaller diameter and include a rigid
backing member to permit the application of a uniform pressure. A
housing in the form of an arcuate shaped resilient holding or
clamping member 42 pivotally mounted, as hereinafter described, on
a support member 43, releasably holds the elastic tubing 41 with a
portion of the surface thereof extending beyond the clamping member
42 in pressure contact with the recording surface of drum 10. The
end 44 of tubing 41 is closed, and the opposite end 45 of tubing 41
is clamped by means of a suitable clamp 46 in fluid tight, fluid
flow communication with a conduit 47 which includes a three way
valve 48 such as a solenoid valve, which places the interior of the
tubing 41 in fluid flow communication with either a source of fluid
pressure (not shown), such as air pressure, through conduit 49 of
the atmosphere through a vent conduit 51. The holding member 42 is
provided with axially spaced screw clamps 52 for compressing and
releasing the free ends of the holding member 42 to grip and
support the inflated tubing 41 in a manner such that a portion of
the tubing 41 extends beyond the holding member 42 and in pressure
contact with the recording surface of the drum 10.
The holding member 42 is pivotally mounted on a rod 53 which is
telescopically received in aligned apertures 54 in downwardly
extending brackets 55 fixedly mounted to the ends of the holding
member 42. The rod 53 is removably supported in aligned apertures
56 in axially spaced upwardly extending brackets 57 fixedly mounted
to the supporting member 43 with axial movement of the rod 53 being
limited by caps 58 removably mounted on the ends of the rod 53.
A pressure loading mechanism, comprised of a resilient member 59,
is fixedly supported, at one end, to the support member 43 by a
fastening means, such as a screw 61, and is positioned in
deformation, at the upper end, in abutment with the holding member
42, thereby biasing the pivotally supported holding member 42
toward the recording surface of drum 10. A stop mechanism,
comprised of axially spaced screws 62, rotatably mounted in the
support member 43, are positioned with the shanks thereof in
abutment with the brackets 55 of holding member 42, thereby
preventing further movement of the holding member 42 toward the
recording surface of drum 10. Thus, a proper positioning of the
screws 62 determines the position of the holding member 42 with
respect to the recording surface of the drum 10, with the holding
member 42 being maintained in this position by the resilient member
59 urging the holding member 42 toward the recording surface of
drum 10.
The cleaning station further includes a removable trough like
container 63, positioned below the horizontal axis of the drum 10
to collect any toner particles which may gravitate away from the
recording surface of drum 10.
In operation, the elastic tube 41 is inflated to a predetermined
pressure and the screws 62 are set in a manner such that the
holding member 42 holds the inflated tube 41 in sealing contact
with the recording surface of drum 10, with the holding member 42
being positioned closely adjacent to but not contiguous with the
recording surface of drum 10. The holding member 42 is maintained
in this position by the resilient member 59. If required, a dry
solid hydrophobic lubricant is employed in finely divided form and
admixed with the toner particles in the development station for
introduction onto the recording surface. It is to be understood,
however, that in many cases there is no necessity for a
lubricant.
The elastic tubing 41 which is in sealing contact with the
recording surface of drum 10 prevents residual toner from moving
past the tubing and, therefore, there is a buildup of toner on the
recording surface of the drum 10. Periodically, the valve 48
connects the interior of the tubing 41 to vent for a short period
of time which causes the tubing 41 to deflate, thereby breaking the
sealing contact between the tubing 41 and the recording surface of
drum 10, whereby the accumulated particles are transported by the
rotating drum 10 into the developing apparatus where the toner is
removed by the cascading developer. The valve 48 is then switched
to connect the tubing 41 to the source of pressure, thereby
reinflating the tubing 41 and reestablishing the sealing contact
between the tubing 41 and the recording surface of drum 10. In this
manner, the recording surface rotated past the cleaning station 40
is maintained free of residual toner particles and such residual
toner particles instead of being wasted as in conventional cleaning
apparatus are accumulated and recycled for use in the development
portion of the process.
Another embodiment of the invention is illustrated in FIG. 3. The
embodiment of FIG. 3 is similar to the embodiment of FIG. 1, except
for the manner in which the contact between the inflated member and
the recording surface is periodically interrupted and, therefore,
like parts are designated by like prime numerals.
Referring to FIG. 3, there is shown an inflated elastic member 41'
releasably held in pressure contact with the recording surface of
drum 10' by a holding member 42' pivotally supported on a
supporting member 43'. In the embodiment of FIG. 3, the inflated
member 41' may be an elastic member which has been previously
inflated in that there is no necessity to inflate and deflate the
elastic member to establish and interrupt contact between the
elastic member and the recording surface. Accordingly, the
apparatus need not include special means for providing a source of
fluid pressure.
The inflated tube 41' normally rests in pressure contact with the
recording surface of drum 10' due to the pressure applied by the
resilient member 59'. The holding member 42' is provided at one end
with a cam follower 101 which extends radially inward beyond one of
the axial ends of the recording surface of drum 10' for engagement
with a cam 102 rigidly mounted on the end surface of drum 10' for
rotation therewith. The cam follower 101 upon engaging cam 102
follows the curved surface of cam 102 causing the holding member
42' to be lifted away from the recording surface of drum 10',
thereby interrupting the contact between the inflated tube 41' and
the recording surface of drum 10'. The interruption of the contact
between the inflated member 41' and the recording surface of drum
10', permits the accumulated toner particles to be carried by the
recording surface of drum 10' to the development station at which
point the toner is removed by contact with cascading developer.
Another embodiment of the invention is illustrated in FIG. 4. The
embodiment of FIG. 4 is similar to the embodiment of FIG. 1 except
for the manner in which the contact between the inflated member and
the recording surface is periodically interrupted and, therefore,
like parts are designated by like double prime numerals. Similar to
the embodiment of FIG. 3, the elastic member is preferably inflated
prior to being inserted into the apparatus.
Referring to FIG. 4, there is shown an inflated elastic member 41"
releasably held in pressure contact with the recording surface of
drum 10" by a holding member 42" pivotally supported on a
supporting member 43". The inflated tube 41" normally rests in
pressure contact with the recording surface of drum 10" due to the
pressure applied by the resilient member 59".
The recording surface of drum 10" is provided with adjacent
transverse grooves 201 and as drum 10" rotates, the residual toner
on the recording surface of drum 10" is dislodged and carried
thereon by the inflated tube 41" until contact is interrupted
between the inflated tube 41" and the recording surface by grooves
201. The toner particles are carried in the grooves 201 to the
development station at which point the toner is removed by
cascading developer. Although two grooves have been particularly
shown, it is to be understood that the recording surface may be
provided with less than or more than two grooves and that if two or
more grooves are employed it is not necessary that each groove
extend across the entire surface.
The stop screw 62" is adjusted in a manner such that the holding
member 42" holds the inflated tube 41" in contact with the
recording surface, but prevents the inflated tube 41" from removing
accumulated toner from the grooves 201. The grooves 201 in addition
to functioning as a reservoir for accumulated toner remove residual
toner adhering to the inflated tube 41" by the wiping action
between the faces 202 of grooves 201 and the inflated tube.
Numerous modifications and variations of the hereinabove described
embodiments are possible within the spirit and scope of the
invention. For example, the embodiments have been particularly
described with reference to an annular recording surface on a
rotating drum, and it is to be understood that the present
invention is equally applicable to other types of recording
surfaces; e.g., movable belts.
Similarly, the lubricant, if required, may be introduced into the
machine in a manner other than with the toner as particularly
described with respect to the illustrated embodiments. The
lubricant could be introduced through a suitable dispenser prior to
or after the development station or may be incorporated into the
reusable electrostatographic surface.
The cleaning system of the present invention may be supplemented
with other devices to aid in the cleaning process. Thus, for
example, there may be provided a pre-cleaning station which would
include a corona discharge device; e.g., similar to the device
employed for precharging the recording surface, to charge the
recording surface and residual toner, subsequent to the transfer
station, and prior to the cleaning step. The polarity of the charge
is dependent upon the particular results desired. Thus, for
example, the corona discharge device is employed to provide a
charge polarity which increases the electrostatic attraction
between the residual toner and the recording surface in a situation
in which elimination of the possibility of toner gravitating away
from the recording surface is desired. Alternatively, the charge
may be of a polarity which reduces the electrostatic attraction
between the residual toner and the recording surface which in turn
facilitates removal of residual toner from the recording
surface.
Similarly, the contact between the inflated member and the
recording surface may be interrupted in a manner other than those
particularly described. For example, the inflated member may be
moved away from contact with the recording surface by electrical or
magnetic means in addition to the various mechanical means
particularly described. Various mechanisms for interrupting contact
between the inflated member and the recording surface should be
readily apparent to those skilled in the art from the teachings
herein.
As another alternative, the accumulated toner could be removed from
the recording surface without interrupting contact between the
inflated member and recording surface; e.g., the accumulated toner
may be periodically removed from the recording surface by a brush
or other suitable means.
As a further alternative, a plurality of inflated members may be
employed to clean the recording surface. Each of the plurality of
inflated members may be each coextensive with the recording surface
whereby any residual material moving past the first member is
removed by the second member. Alternatively, the plurality of
members may be positioned in a manner such that each member extends
over a portion of the recording surface, with the members being
staggered and overlapped to insure coverage of the entire axial
length of the recording surface. Similarly, although the invention
has been described with reference to the use of a cascade
development technique, other development techniques may also be
employed; e.g., fur brush development, fluidized development and
the like. Representative patents in which various development
techniques are described include: U. S. Pat. No. 2,895,847 to Mayo;
U. S. Pat. No. 2,251,706 to Walkup; and U. S. Pat. No.
2,874,063.
It is to be further understood that the present invention is also
applicable to electrostatographic processes other than of the
electrophotographic type, such as for example, electrostatic
processes in which a latent electrostatic image is formed by a
pulsing electrode. Thus, as should be apparent, although the
present invention is particularly applicable to an
electrophotographic copying machine, the overall invention is not
limited to a particular technique for forming or developing a
latent electrostatic image.
Numerous modifications and variations of the present invention are
possible in light of the above teachings and, therefore, within the
scope of the appended claims the invention may be practiced other
than as particularly described.
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