U.S. patent number 3,780,391 [Application Number 05/261,478] was granted by the patent office on 1973-12-25 for apparatus for cleaning a residual image from a photosensitive member.
This patent grant is currently assigned to Eastman Kodak Company. Invention is credited to Donald D. Leenhouts.
United States Patent |
3,780,391 |
Leenhouts |
December 25, 1973 |
APPARATUS FOR CLEANING A RESIDUAL IMAGE FROM A PHOTOSENSITIVE
MEMBER
Abstract
A residual toner image remaining after transfer of a developed
image from a photoconductive surface is cleaned therefrom in one
embodiment by a conductive cleaning brush mounted in a vacuum
chamber and having a flicker bar which is used to apply a potential
to the brush opposite that of the residual toner particles to be
removed from the photoconductive surface. In another embodiment,
the brush is divided into a number of electrically insulated
segments so that the polarity of the potential applied to a portion
of the brush coming in contact with the photosensitive surface is
opposite to the charge on the residual toner particles and a
potential applied to a segment spaced from the photoconductive
surface is the same as the charge on the toner particles on the
brush segment so that they are repelled therefrom to clean the
toner particles from the brush.
Inventors: |
Leenhouts; Donald D.
(Rochester, NY) |
Assignee: |
Eastman Kodak Company
(Rochester, NY)
|
Family
ID: |
22993478 |
Appl.
No.: |
05/261,478 |
Filed: |
June 9, 1972 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
88628 |
Nov 12, 1970 |
|
|
|
|
Current U.S.
Class: |
15/1.51; 15/308;
399/353 |
Current CPC
Class: |
G03G
21/0035 (20130101); G03G 2221/0005 (20130101) |
Current International
Class: |
G03G
21/00 (20060101); G03g 015/00 () |
Field of
Search: |
;15/1.5 ;355/15 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Machlin; Leon G.
Parent Case Text
This application is a continuation of application Ser. No. 88,628,
filed Nov. 12, 1970, now abandoned.
Claims
I claim:
1. A cleaning device for cleaning residual toner particles, at
least some of said residual toner particles having a charge of a
first polarity thereon, from a photoconductive surface, said
cleaning device comprising:
a. an electrically conductive, movable, fibrous cleaning element,
said element being divided into at least first and second
electrically insulated segments;
b. means for mounting said element so that a portion of the element
fibers contacts said photoconductive surface;
c. means for moving said element relative to said photoconductive
surface along an endless path;
d. first flicking means mounted in interference relation to the
fibers of said element, said first flicking means being positioned
to contact said segments of said element before said segments
contact said photoconductive surface;
e. second flicking means mounted in interference relation to the
fibers of said element, said second flicking means being positioned
to contact said segments of said element after said segments
contact said photoconductive surface to dislodge toner particles
from said segments; and
f. potential applying means for applying an electrical potential to
said first flicking means of a second and opposite polarity of that
of the residual toner particles so that said toner particles are
attracted to said segments of said element.
2. Apparatus for removing residual toner particles from a
photoconductive surface, said apparatus comprising:
a. a movable element, said element including at least first and
second electrically conductive segments, said segments being
electrically insulated from each other;
b. means for mounting said element so that said segments are
sequentially movable between a charging position whereat said
segments are charged to a first potential, a contacting position
whereat at least one of said segments contacts the photoconductive
surface, and a removing position whereat said segments are charged
to a second potential;
c. means for sequentially moving said segments between said
charging, contacting and removing positions;
d. first potential applying means cooperatively associated with
said segments at said charging position for applying a first
potential to said segments prior to said segments contacting the
photoconductive surface, said first potential being of a polarity
and magnitude sufficient to attract the residual toner particles
from the photoconductive surface to said segments charged to said
first potential; and
e. second potential applying means cooperatively associated with
said segments at said removing position for applying a second
potential to said segments after completion of said segments
contact with the photoconductive surface, said second potential
being of a polarity and magnitude sufficient to repel the residual
toner particles from said segments.
3. A cleaning device as claimed in claim 1, further including:
means for moving air relative to said element to withdraw from the
vicinity of said element toner particles dislodged from said
segments.
4. A cleaning device as claimed in claim 1 wherein some of said
residual toner particles are charged to said first polarity and
other of said residual particles are charged to said second
opposite polarity, said cleaning device further comprising:
potential applying means for applying an alternating potential to
said second flicking means to repel toner particles from said
segments of said element.
5. A cleaning device for cleaning electrically charged residual
toner particles from a photoconductive surface, said device
comprising:
a. an electrically conductive, rotatable cleaning brush mounted
within a shroud, said brush being divided into at least first and
second electrically insulated segments;
b. means for mounting said brush so that a portion of the brush
fibers contacts the photoconductive surface;
c. means for rotating said brush;
d. means to cause relative motion between the axis of said brush
and the photoconductive surface;
e. charging means for applying a uniform electrical charge of a
first polarity to the photoconductive surface and the residual
toner particles prior to the surface's contacting said brush;
f. a first electrically conductive contactor mounted in
interference relation to the brush fibers, said first contactor
being positioned so that it contacts said brush segment before said
brush segments contact the photoconductive surface;
g. potential applying means connected to said first contactor for
applying to the brush fibers an electrical potential of a second
polarity opposite said first polarity to attract the residual toner
particles from the photoconductive surface to said brush
segments;
h. a second electrically conductive contactor mounted in
intereference relation to the brush fibers, said second contactor
being positioned so that it contacts said brush segments after said
brush segments contact the photoconductive surface to dislodge
toner particles from said brush segments; and
i. vacuum means connected to said shroud for withdrawing from the
vicinity of said brush an airstream containing therein suspended
toner particles dislodged from said brush.
6. A cleaning device as claimed in claim 5 further including:
second potential applying means for applying to said second
contactor an electrical potential of said first polarity to repel
toner particles from said brush segments.
7. A cleaning device as claimed in claim 5, further including:
means for illuminating said photoconductive surface to actinic
radiation prior to said surface's contacting said brush.
8. A cleaning device as claimed in claim 7 wherein said
illuminating means is activated subsequently to said charging
means.
9. A cleaning device for cleaning residual toner particles from a
photoconductive surface, some of the residual toner particles being
charged to a first polarity and other of said residual toner
particles being charged to a second polarity, said cleaning device
comprising:
a. an electrically conductive, rotatable cleaning brush mounted
within a shroud, said brush being divided into at least first and
second electrically insulated segments;
b. means for mounting said brush so that a portion of the brush
fibers contact said photoconductive surface;
c. means for rapidly rotating said brush;
d. means to cause relative motion between the axis of said brush
and said photoconductive surface;
e. a first electrically conductive contactor mounted in
interference relation to the brush fibers, said first contactor
being positioned to contact said segments of said brush before said
segments contact said photoconductive surface;
f. a second electrically conductive contactor mounted in
interference relation to the brush fibers, said second contactor
being positioned to contact said segments of said brush after said
segments contact said photoconductive surface to dislodge toner
particles from said brush;
g. a corona discharge electrode positioned and disposed to apply a
uniform electrostatic charge of said first polarity to said
photoconductive surface ahead of said brush in the direction of
movement of said photoconductive surface;
h. a source of illumination positioned and disposed to illuminate
said photoconductive surface to actinic radiation downstream of
said corona discharge electrode and ahead of said brush in the
direction of movement of said photoconductive surface;
i. a source of direct current potential connected to said first
contactor for applying to said brush segments an electrical
potential of said second polarity so that said residual toner
particles are attracted to said brush segments;
j. a source of alternating current potential connected to said
second contactor for applying to said brush segments electrical
potentials of said first and second polarities to repel said toner
particles from said brush segments; and
k. vacuum means connected to said shroud for withdrawing from the
vicinity of said brush an airstream containing therein suspended
toner particles dislodged from said segments of said brush.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to apparatus for removing electrostatically
adhering particles from a photoconductive member, and more
particularly to improved apparatus for cleaning residual toner
particles from an electrophotoconductive surface.
2. Description of the Prior Art
In a conventional electrophotographic process, an electrostatic
image is formed on a photoconductive surface as by placing a
uniform electrostatic charge on the photoconductive surface which
surface is subsequently exposed to a radiation pattern to dissipate
the charge in the exposed areas. This image is then toned by a
suitable developing material, such as dry toner powder. The
developed image is then transferred to a receiver. However, a small
amount of residual toner usually remains on the photoconductive
surface which must be removed therefrom prior to the forming and
transfer of subsequent images to prevent ghost images from being
formed during subsequent transfers.
Various attempts have been made to clean photoconductive surfaces.
One method of cleaning a photoconductive surface utilizes a
rotating brush. One example of a rotating cleaning brush is
disclosed in U.S. Pat. No. 2,751,616 to Turner et al wherein the
brush is treated with an impregnating material to control its
conductivity. The brush is mounted within a dust hood and provided
with a grounded flicker bar that contacts the brush fibers just
before the brush contacts the photoconductor. The electrical
conductivity of the brush and flicker bar assist in the
neutralization of the residual charge on the toner particles. U.S.
Pat. No. 2,752,271 to Walkup et al discloses the placing of a
negative electrostatic charge on the photoconductive surface
carrying the residual image and then rapidly brushing the
photoconductive surface in the presence of a vacuum. To counteract
the electrostatic attraction between the brush and particles to
facilitate the release of such particles to the vacuum, an
electrostatic charge is applied to the brush following brushing of
the photoconductive surface. U.S. Pat. No. 3,313,623 to Bixby
discloses a rotatable cleaning brush to which a potential is
applied to assist in removal of toner from a photoconductive
surface. In some environments, such cleaning devices have not been
found entirely satisfactory. Residual toner particles remaining on
the photoconductive surface and/or cleaning element have resulted
in scumming and scratching of the photoconductive surface.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an improved
apparatus for cleaning toner particles from a photoconductive
surface.
Another object of the invention is to provide an improved apparatus
for cleaning residual toner particles remaining after transfer of a
developed image from a photoconductive surface.
Yet another object of the invention is to provide improved
apparatus for continuously removing toner particles from a cleaning
brush.
Still another object of the invention is to remove residual toner
particles from a photoconductive surface with reduced scumming and
scratching of the surface.
These and other objects are accomplished in accordance with one
disclosed embodiment of the invention, by providing an electrically
conductive cleaning brush mounted in an air flow or vacuum chamber,
to which brush an electrical potential is applied by means of a
flicker bar that contacts the fibrous brush material as the brush
rotates. Maintaining the brush at a potential relative to ground
attracts the residual toner particles to the brush by overcoming
the electrostatic forces which hold the particles to the
photoconductive surface. The flicker bar loosens the toner
particles from the brush so that they are carried away from the
brush by the air flow. In some cases, some of the residual toner
particles will have a potential of positive polarity and others a
potential of negative polarity. In these cases the speed and
efficiency of the cleaning operation can be improved by applying to
the residual toned image a charge of a polarity opposite to that
applied to the cleaning brush before contacting the brush with the
photoconductive surface. A flooding light is then used to reduce
any potential remaining on the untoned areas of the photoconductive
surfaces.
In another disclosed embodiment of the invention a cleaning brush
is provided with a number of segments each electrically insulated
from each other. A first flicker bar is utilized to apply a
potential to a segment of the brush to attract the toner particles
to this segment as this segment wipes or rubs against the
photoconductive surface and a second flicker bar is utilized to
apply an opposite potential to a brush segment when the segment is
no longer in contact with the photoconductive surface to repel the
toner particles from that segment of the brush for removal by the
air flow.
Other objects and advantages of the invention will become apparent
from the detailed description of the preferred embodiments which
follows.
BRIEF DESCRIPTION OF THE DRAWINGS
In the detailed description of the preferred embodiments of the
invention presented below, reference is made to the accompanying
drawings wherein corresponding parts are identified by like
numerals and in which:
FIG. 1 is a diagrammatic side elevation, partly in section, showing
one embodiment of the present invention for cleaning a
photoconductive belt of a conventional electrophotographic
mechanism.
FIG. 2 is a fragmentary side elevation, partly in section, similar
to FIG. 1, showing additional apparatus for charging and
illuminating the photoconductive belt.
FIG. 3 is a fragmentary side elevation, partly in section, similar
to FIG. 2, but showing another embodiment of the invention
utilizing a segmented brush.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the drawings and in particular to FIG. 1, there is
shown an electrophotographic mechanism M, which includes an endless
photoconductive belt 2 extending around spaced rollers 4 and 6 and
is illustrated as being driven by motor 8 through a drive belt 10.
The belt 2 is driven past a charging station 12 which places a
uniform electrical charge (either positive or negative) over its
photoconductive surface; an exposure station 14 whereat the belt is
exposed to a radiation pattern, such as a light image from an
original, to discharge the photoconductive surface in accordance
with the radiation pattern to form an electrostatic latent image; a
developing station 16 whereat the latent image is developed by
depositing toner thereon; a transfer station 18 whereat the
developed image is transferred to a receiver; and finally a novel
cleaning apparatus C whereat the photoconductive surface of the
belt 2 is cleaned of residual toner particles. The charging,
exposure, developing and transfer stations can be of any form known
in the prior art, and may be selected as required by one skilled in
the art.
Cleaning apparatus C includes a rotatable brush 22 which may be
made of a soft fibrous material such as natural or artificial fur
or flannel that has been rendered electrically conductive, as for
example, by impregnating the brush fibers with nickel. The brush 22
is rotatably mounted as shown so that a portion of the brush fibers
contacts the area of the photoconductive belt 2 to be cleaned. A
platen 24 on the side of the photoconductive belt 2 opposite that
of the brush 22 is provided to support the belt in frictional
contact with the brush. Alternatively, platen 24 can be replaced by
a roller. Advantageously, the brush 22 is rotated by means (not
shown) so that it moves in a direction opposite to the movement of
the photoconductive belt 2 at the point of contact therewith. An
electrical potential opposite in polarity to the charge on the
residual toner particles is applied to the brush 22, which is
electrically isolated from its mountings, from a source 28 by means
of a metal contactor 26 which touches the brush fibers as the brush
rotates. Conveniently, the contactor 26 is also used as a flicker
bar to loosen the toner particles attracted to the brush 22.
A shroud or housing 30 extends around a substantial portion of the
brush 22 as shown, and is illustrated as being provided with an air
inlet 32 and an air outlet 34 to which a vacuum can be applied to
provide air moving means to withdraw the toner particles removed
from the belt 2 from the vicinity of the brush. The toner particles
are carried by the air flow to a disposable filter bag (not shown)
or other equivalent device which can be easily replaced when the
electrophotographic mechanism is normally shut down.
It has been found that in certain instances that some of the
residual toner particles have a potential of positive polarity
while other particles have a potential of negative polarity. In
such instances, the conductive brush 22 with fibers charged to one
polarity are not as effective in removing toner particles of the
same polarity as the fibers. In such cases the speed and efficiency
of the cleaning apparatus C can be improved as shown in FIG. 2 by
providing means, such as a corona discharge device 36 upstream of
brush 22. The corona 36 applies a uniform charge to the
photoconductive surface of the belt 2 and the residual toner image
of a polarity opposite to the potential applied to the brush 22 by
the source 28. The charging by the corona 36 increases the charge
on the residual image and increases the attraction between the
image and the brush fibers. To reduce the charge in the untoned
areas of the photoconductive belt 2 and thereby decrease the
attraction between the photoconductive belt and the residual toner
image, the corona charging is either accompanied by or followed by
a flooding light 38 which is directed onto the photoconductive
surface of the belt. Flooding light 38 also prevents charge buildup
on the photoconductive surface as a result of charging with corona
36.
In the embodiment of the invention shown in FIG. 3,
electrophotographic mechanism M' includes cleaning apparatus C'
having a conductive cleaning brush 39, which is illustrated as
having an insulative core 40 with spaced radial fins 41 to divide
the brush into a plurality of segments, such as segments 42, 44, 46
and 48 respectively, each electrically insulated from the others.
The brush segments are made of fur or other soft fibrous material
that have been treated with an electrically conductive impregnating
material. An electrical potential which will attract the residual
toner particles during the wiping of the photoconductive surface of
the belt 2 is applied to the brush fibers of each brush segment
from a source 50 through a metal contactor 52 as the brush segments
42, 44, 46 and 48 pass the contactor 52. In FIG. 3, contactor 52 is
shown applying an electrical potential to the brush fibers of brush
segment 48. After the brush fibers have wiped the photoconductive
surface of the belt 2 and are no longer in engagement therewith, an
opposite potential which will repel the toner particles from the
brush fibers is applied to each brush segment from a source 54
through a metal contactor 56 as the brush segments pass the
contactor 56. In FIG. 3, contactor 56 is shown applying such
potential to the brush fibers of brush segment 44. The metal
contactors 52 and 56, in similarity to contactor 26, also function
as flicker bars. Contactor 52 compresses the brush fibers of the
brush 39 as they pass thereby. After being compressed by the
contactor 52, the brush fibers spring outward assisted by
centrifugal force and contact the photoconductive surface of the
belt 2 with more than normal wiping force. Contactor 56 functions
to assist in loosening the toner particles from the brush fibers so
that they may be removed by vacuum means which includes shroud
58.
Optionally, the corona discharge device 36 and source of
illumination 38 may be included, as previously described with
respect to FIG. 2, to assist in removing bi-polar toner particles.
Removal of bi-polar toner particles from the brush may be further
assisted by utilizing alternating current for the source of
potential 54 so that toner of both polarities will be repelled from
the brush.
From the foregoing, the advantages of the present invention are
readily apparent. Novel cleaning apparatus and methods have been
disclosed which continuously remove toner particles from the brush.
This is accomplished by use of a conductive member which serves the
dual function of a flicker bar and a device for applying a
potential to a cleaning brush. Accumulation of toner particles on
the brush is, therefore, held to minimum levels to reduce scumming
and the possibility of damage to the photoconductive surface.
The invention has been described in detail with reference to
preferred embodiments thereof, but it will be understood that
variations and modifications can be effected within the spirit and
scope of the invention .
* * * * *