Method of and system for cleaning a charge inducing member

A system for cleaning a charge inducing member comprising a cleaning element for establishing relative lineal as well as rotary movement between the cleaning element and charge inducing member. Embodiments include various mechanisms for imparting axial reciprocal motion to the cleaning element and for disabling reciprocation of the cleaning element or separating the cleaning element and charging member from each other during sensitive portions of a photoduplication cycle.

TECHNICAL FIELD 
The present invention relates to contact charge inducing members for 
charging photoconductive elements, such as drums or belts. The invention 
has particular applicability to electrophotographic apparatus, such as 
copiers, printers, facsimile machines and the like. 
BACKGROUND ART 
Conventional electrophotographic apparatus, such as copiers, printers, 
facsimile machines, etc., comprise an imaging surface, such as a 
photoconductive element, normally in the form of a drum or belt. Arranged 
in timed sequence around the imaging surface are a plurality of processing 
stations for performing various functions. These processing stations may 
comprise stations for charging the imaging surface, electrostatically 
forming a latent image on the imaging surface, developing the latent 
electrostatic image with a developer commonly referred to as toner, 
transferring the developed image from the imaging surface to a substrate 
such as paper, feeding paper to the transferring station, cleaning the 
imaging surface, i.e., removing residual toner on the imaging surface, and 
fixing the transferred developed image on the paper. 
A typical reproduction operation comprises charging the imaging surface, 
such as a photoconductive drum, and exposing the charged surface to a 
light pattern of an original image to be reproduced thereby selectively 
discharging the imaging surface in accordance with the original image. The 
resulting pattern of charged and discharged areas on the surface of the 
photoconductive drum forms an electrostatic charge pattern or 
electrostatic latent image conforming to the original image. 
The latent electrostatic image is developed by contacting it with finely 
divided toner which is held by electrostatic force on the imaging surface. 
The toner image is transferred to a substrate, such as paper, in a 
transferring device into which paper is fed by a registration roller 
toward the drum in synchronization with drum rotation. As the leading edge 
of the paper abuts the drum, electrostatic forces adhere the two together, 
and the transferring device transfers a toner image from the 
photoconductive drum to the paper. After transfer, the toner image is 
fixed to form a permanent record. 
Subsequent to development, and after transfer of the developed image to the 
paper, some toner inevitably remains on the photoconductive drum, held 
thereto by electrostatic and/or Van der Wals force. Additionally, other 
contaminants, such as paper fibers, toner additives, Kaolins and various 
other forms of debris, have a tendency to be attracted to the charge 
retentive surface. 
Contemporary commercial automatic copiers/reproduction machines comprise an 
electrostatographic imaging surface, which may be in the form of a drum or 
belt. The imaging surface moves at high rates in timed unison relative to 
a plurality of processing stations. This rapid movement of the 
electrostatographic imaging surface requires vast amounts of toner to be 
employed during development. Associated with the increased amounts of 
toner is the difficulty in removing residual toner remaining on the 
imaging surface subsequent to transfer. 
One type of device conventionally employed for charging the imaging surface 
of a photoconductive member is a corona charger normally positioned 
slightly spaced apart from the surface of the imaging surface for applying 
a surface charge thereto. Typically, a corona charging device comprises a 
wire electrode and a shield electrode to which is normally applied a 
relatively high voltage, on the order of 4 to 8 kilovolts, to induce 500 
to 800 volts of surface potential on the imaging surface. Corona chargers 
are of relatively low charging efficiency, because most of the discharging 
current from the wire electrode flows to the shield electrode, leaving a 
small percentage of the total discharging current flowing to the imaging 
member to be charged. Another disadvantage attendant upon employing a 
corona charger is the generation of ozone which constitutes a health 
hazard and is, therefore, environmentally undesirable. Accordingly, when 
employing a corona charger it is necessary to install filtering and air 
distribution systems in any environment in which the electrostatographic 
apparatus is situated. In addition, image blurring occurs as a result of 
the oxidation of the image transfer components and deterioration of the 
photoconductive surface. Still another disadvantage attendant upon 
employing a corona charger is contamination of the wire electrode by fine 
dust attracted by the electrostatic field created by the electrode, 
thereby necessitating periodic cleaning and/or replacement of the wire 
electrode. 
The disadvantages associated with corona chargers have led to the 
implementation of alternatives to the corona chargers, such as a contact 
type charge inducing member as disclosed in Japanese laid open 3-130,787. 
The disclosed system comprises a contact charge inducing member which is 
maintained in contact with the surface of a charge receiving member, e.g., 
a photoconductive drum, thereby charging the photoconductive drum at an 
advantageously relatively low voltage. Since a discharge is not 
established, ozone is not generated and the accumulation of dust on the 
wire electrode avoided. 
As shown in FIG. 1, the prior art apparatus comprises photoconductive drum 
60, a contact charge inducing member in the form of charging roller 62 
connected to a relatively low voltage power supply 64 via conductive 
spring 61. The apparatus also comprises cleaning element 63 which is urged 
into contact with the surface of charging roller 62 upon energizing 
solenoid 65. Cleaning element 63 is made of felt, or a suitable foam such 
as a polyurethane, or a suitable elastomer such as an 
ethylene-propylene-diene-monomer (EPDM) elastomer. Solenoid 65 enables 
periodic movement of cleaning element 63 into and out of contact with 
charging roller 62. 
In operation, solenoid 65 is normally off so that the armature extends out 
of solenoid 65 and cleaning element 63 is spaced apart from, i.e., out of 
contact with, charging roller 62. During operation, toner and other 
contaminants inevitably accumulate on charging roller 62, as from the 
surface of drum 60, decreasing its charge inducing efficiency. In 
addition, such toner and other contaminants tend to redeposit on 
photoconductive drum 60, resulting in poor quality reproductions. When 
solenoid 65 is switched on, the armature is drawn into the solenoid, 
extending cleaning element 63 into contact with charging roller 62 to 
remove toner and other contaminants therefrom while charging roller 62 
rotates due to frictional engagement with photoconductive drum 60. 
Another prior art cleaning element is disclosed in Japanese laid open 
3-101,768. The cleaning element is also made of felt or other suitable 
materials, such as polyurethane foam or rubbers. 
A conventional charging roller 62, as shown in FIG. 2A, normally comprises 
a conductive metal core 65 surrounded by a layer of elastomeric material 
62a, such as rubber or an elastomeric resin, and a surface layer 62b 
having a thickness in the range of about 4 to about 14 microns and a 
hardness greater than that of underlying layer 62a. 
Because the underlying layer 62a of elastomeric material is inherently 
formed with surface irregularities, as shown in FIG. 4, the outer surface 
layer 62b conforming to the shape of the underlying layer, is also 
irregular. This inherent irregular outer surface layer 62b is 
characterized by a convex and concave surface topography comprising 
crevices, recesses, etc., renders it particularly receptive to the 
accumulation of embedded or lodged finely divided material such as toner 
and other contaminants. Toner is a particularly troublesome contaminant, 
since its particle size is such that it easily penetrates crevices on the 
surface of a charge inducing member so that the toner tends to accumulate 
in the concave portions. 
With reference to FIG. 2B, despite the use of the prior art cleaning 
elements, which were basically stationary while the charging roller 
rotates, toner and other contaminants (Tn) inevitably accumulate and lodge 
in crevices and recesses on the irregular surface of charging roller 62 
(FIG. 2C). Such Tn tend to become embedded or lodged between charging 
roller 62 and cleaning element 63 as shown in FIG. 3, resulting in the 
accumulation of Tn on the surface of charging roller 62. In addition, the 
accumulation of Tn between cleaning element 63 and charging roller 62 
creates friction on the surface of charging roller 62 thereby 
disadvantageously imparting vibrations to the photoconductive element 
resulting in poor quality reproduction. After a period of time, the 
accumulated Tn causes nonuniform charging resulting noticeably poor 
quality reproductions. 
With reference now to FIGS. 5A and 5B, an area 70 of the surface of 
charging roller 62, having the irregular surface as shown in FIG. 4, has 
been cleaned by a prior art rotational element 63. The surface is 
characterized by an overlapping area 71 which has not been effectively 
cleaned by the prior art rotational cleaning element 63 due to poor 
contact therebetween because of the irregular surfaces of both the 
cleaning element and rotational element. This is because area 71 is in the 
"shadow" of area 70 and will not be "seen" by element 62 as it sweeps over 
the rotational element 63. Thus, as illustrated in FIG. 6A, accumulated Tn 
will remain embedded in surface crevices and recesses 62C, even after 
cleaning. 
Several prior art techniques have been developed to remove toner and other 
contaminants from a photoconductive drum after transfer of the developed 
image to a substrate. See, for example, Japanese laid open 60-134275. 
DISCLOSURE OF THE INVENTION 
An object of the present invention is an electrostatographic apparatus 
which reproduces images having improved quality. 
Another object is improved cleaning of a direct contact type charge 
inducing member. 
Another object of the invention is improved cleaning of a direct contact 
type charge inducing member for charging a photoconductive element of an 
electrographic image forming apparatus. 
A further object is more effective removal of accumulated toner and other 
contaminants from the surface of a direct contact type charge inducing 
member of a photocopier or other electrostatic image forming apparatus. 
A still further object of the invention is in prolonging the life of a 
direct contact type charge inducing member. 
Additional objects, advantages and other features of the invention will be 
set forth in part in the description which follows and in part will become 
apparent to those having ordinary skill in the art upon examination of the 
following or may be learned from practice of the invention. The objects 
and advantages of the invention may be realized and attained as 
particularly pointed out in the appended claims. 
According to the present invention, the foregoing and other objects are 
achieved in part by an apparatus comprising a charge receiving member upon 
which an electrostatic charge is to be formed, an electric charge inducing 
member positioned for inducing an electric charge on the charge receiving 
member, a cleaning element for cleaning the charge inducing member, and 
means for maintaining the cleaning element and the charge inducing member 
in contact with each other while imparting relative lineal motion 
therebetween. 
Another aspect of the invention is an electrostatic image forming apparatus 
having a photoconductive element, such as a rotating photoconductive drum, 
upon which an electrostatic latent image is to be formed, a toner 
dispenser for transferring toner to the photoconductive drum, an electric 
charge inducing member, and positioning means for positioning the electric 
charge inducing member in direct surface engagement with the 
photoconductive drum. A source of electric potential is provided to 
establish an electric field between the charge inducing member and the 
photoconductive drum. The apparatus further includes means for advancing a 
substrate, such as paper, to the photoconductive drum and means for 
transferring a toner developed image corresponding to the latent image 
from the photoconductive drum to the paper. In accordance with the 
invention, there is included a cleaning element for cleaning the charge 
inducing member, and means for maintaining the cleaning element and charge 
inducing member in direct surface engagement with each other while 
imparting relative lineal motion therebetween. 
A further aspect of the invention is an apparatus comprising a 
photoconductive drum spaced apart from a cleaning element by a distance 
greater than the diameter of an electric charge inducing roller positioned 
therebetween. Means are provided for moving the electric charge inducing 
roller into direct contact with either the photoconductive drum or the 
cleaning element, but not into direct contact with both the charge 
inducing roller and the photoconductive drum at the same time. An electric 
field is established between the electric charge inducing roller and the 
photoconductive drum only when the charge inducing roller and the 
photoconductive drum are in direct contact with each other, and the motion 
imparting means imparts relative lineal motion between the charge inducing 
roller and cleaning element only when the charge inducing roller and 
cleaning element are in direct contact with each other. 
Still another aspect of the invention is an apparatus comprising a 
photoconductive drum, charge inducing roller, cleaning element, and motion 
imparting means for imparting relative substantially axial motion between 
the cleaning element and charge inducing roller during only a fraction of 
the time the photoconductive drum rotates. 
A further aspect of the invention is a method of cleaning an electric 
charge inducing roller by positioning a cleaning element in direct contact 
with the charge inducing member, and rotating the charge inducing member 
while establishing relative substantially axial movement between the 
cleaning element and the charge inducing member.

DESCRIPTION OF THE INVENTION 
The present invention concerns an apparatus comprising a charge receiving 
member, a charge inducing member for charging the charge receiving member, 
a cleaning element for removing toner and other contaminants from the 
charge inducing member, and motion imparting means for maintaining the 
cleaning element and charge inducing member in contact with each other 
while imparting relative lineal motion between them. An apparatus in which 
the cleaning system of the invention is applicable is an image forming 
apparatus, such as a typical electrostatic image apparatus comprising a 
photoconductive drum as the charge receiving member and a charging roller 
as the charge inducing member as shown in FIG. 7. Photoconductive drum 1 
comprises an electrically conductive base and photoconductive layer 1a, 
such as a photoconductive semiconductor layer of an organic 
photoconductor, amorphous silicon, selenium or the like. Photoconductive 
drum 1 rotates, driven by a motor, timing belt and pulley arrangement (not 
shown), at a predetermined speed in the direction indicated by arrow A 
sequentially in relation to a plurality of processing stations disposed 
about its rotational path of movement. As used herein, "downstream" refers 
to a location along photoconductive drum 1 in the process direction, while 
"upstream" refers to a location along the circumference of photoconductive 
drum 1 in a direction opposite the process direction. 
With continued reference to FIG. 7, charging roller 2 initially contacts 
the surface of photoconductive drum 1 under a predetermined pressure and 
rotates in the direction indicated by arrow B following the rotation of 
photoconductive drum 1. Charging roller 2, supplied with a voltage V from 
an external source, charges photoconductive drum 1 to a substantially 
uniform potential, either positive or negative. Downstream at station 9, 
light rays reflected from an original document are reflected through a 
lens and projected onto a charged portion of the surface of 
photoconductive drum 1 to selectively dissipate the charge thereon. Such 
selective charge dissipation records an electrostatic latent image on the 
circumference of photoconductive drum 1 corresponding to the informational 
area contained within an original document. Alternatively, a laser may be 
provided to imagewise discharge the photoconductive drum 1 in accordance 
with stored electronic information. 
Thereafter, photoconductive drum 1 rotates downstream to development 
station 6 where a rotating magnetic member 6a advances a developer mix 
(e.g., carrier particles and toner) into contact with the latent 
electrostatic image. The toner particles are attracted away from the 
carrier beads by the latent electrostatic image, thereby forming toner 
powder images on the surface of photoconductive drum 1. The development 
station may apply one or more colors of developer material. 
Photoconductive drum 1 then rotates downstream advancing the developed 
latent image to transfer station 7 having an endless belt (not shown). At 
transfer station 7, a sheet of support material or substrate, such as a 
paper copy sheet P, is advanced into contact with the developed latent 
images by cooperating register roller 13 and pressure roller 14. The toner 
powder image is transferred from photoconductive drum 1 to paper P. After 
transfer, the toner image is fused on paper P by a fusing device (not 
shown) and paper P stripped from the endless belt and fed to a discharge 
tray (not shown). Residual toner on photoconductive drum 1 is removed at 
downstream cleaning station 8 by cleaning blade 8a. Any remaining electric 
charge on photoconductive drum 1 is removed by a downstream discharging 
unit (not shown) and the photoconductive drum 1 is then ready to be 
charged again by charging roller 2. 
The apparatus illustrated in FIG. 7 utilizes a charging roller 2 rather 
than a corona charging device and, therefore, avoids its known 
disadvantages. However, as previously noted, a disadvantage of a charging 
roller is the accumulation of toner and other contaminants on the surface 
of the charging roller. The present invention, shown schematically as 
element M in FIG. 7, confronts and solves the prior art problem of 
ineffective cleaning of accumulated toner and other contaminants on the 
irregular surface of a charge inducing member by establishing relative 
lineal movement, preferably relative substantially axial movement, between 
a cleaning element and charge inducing member, to effectively remove 
accumulated toner and other contaminants embedded in topographical 
recesses and crevices on the surface of a charge inducing member. This 
enables the charge inducing member to be maintained free from toner and 
other contaminants for extended periods of time and enabling higher 
quality reproductions. 
Relative lineal movement between the charge inducing member and cleaning 
element can be established by employing means for establishing lineal 
movement of the charging roller and/or means for establishing lineal 
movement of the charge inducing member. It is preferred, however, to 
maintain the charge inducing member stationary in its axial direction and 
employ means for reciprocally moving the cleaning element in a 
substantially axial direction. 
An embodiment of the present invention is shown in FIGS. 8A and 8B, wherein 
photoconductive drum 1 is charged by charging roller 2 when charging 
roller 2 is urged against photoconductive drum 1 by springs 12. Charging 
roller 2 can be a conventional charging roller comprising metal core rod 
15 and surrounding elastomeric layer 16, such as an EPDM elastomer. Metal 
core rod 15 is rotatably supported by bearings 17 at both ends. In this 
embodiment, charging roller 2 is not driven independently, but rotates by 
virtue of frictional contact with photoconductive drum 1. One end of 
photoconductive drum 1 is provided with cam 11 containing circumferential 
groove 18 having a predetermined pattern. An L-shaped holder 21 is affixed 
to cleaning element 19 at the lower surface of leg 21a, while leg 21b, 
functioning as a cam follower, is slidably engaged in circumferential 
groove 18 of cam 11. A guide (not shown) may be provided to maintain the 
position of leg 21b in circumferential grove 18. By appropriate design of 
the pattern of circumferential groove 18, upon rotation of photoconductive 
drum 1 in the direction indicated by arrow A, cam 11 makes one complete 
rotation with the cam follower 21b, thereby reciprocating cleaning element 
19 in a substantially axial direction indicated by arrow C, establishing 
relative substantially axial movement between charging roller 1 and 
cleaning element 19 in addition to relative rotational movement 
therebetween. By effecting relative substantially axially movement between 
charging roller 2 and cleaning element 19, toner and other contaminants 
can be effectively removed from topographical crevices and recesses in the 
irregular surface of charging roller 2, thereby preventing their 
accumulation maintaining charging roller 2 free from toner and other 
containments for long periods of time and improving the quality of 
reproductions. 
Cleaning element 19 can be made of any suitable material capable of 
dislodging toner and other contaminants from the irregular surface of 
charging roller 2. Suitable materials include felt, a sponge-like material 
or foam, such as polyurethane, and an elastomeric material of suitable 
hardness such as a polyurethane rubber. 
In the embodiment depicted in FIGS. 8A and 8B, the movement of cleaning 
element 19 is determined by the design of circumferential groove 18. The 
advantages of this embodiment reside in its relatively simple mechanism 
employing cam 11, circumferential groove 18 and holder 21 to effect 
relative lineal movement between charging roller 2 and cleaning element 
19. Such relative lineal movement prevents toner and other contaminants 
from entering and/or accumulating between cleaning element 19 and charging 
roller 2, whereas conventional cleaning elements, such as that shown in 
FIG. 1 which are incapable of establishing relative lineal movement with 
respect to the charging roller, cannot prevent such entry and/or 
accumulation of toner and other containments. 
Normally, the length of the cleaning element of the present invention is no 
less than the length of the portion of the charge inducing member that 
contacts or charges the charge receiving member, i.e., the imaging length 
of the charge inducing member. Thus, the cleaning element is of sufficient 
length so that, when positioned during cleaning, it extends to at least 
the ends of the charge inducing member. It is preferred that the length of 
the cleaning element is greater than the imaging length of the charge 
inducing member, so that the portion of the cleaning element that contacts 
the imaging length of the charge receiving member is always maintained 
free of toner and other contaminants. It is most preferred that the 
cleaning element has a length such that, when positioned during cleaning, 
the cleaning element always extends beyond each end of the charge inducing 
member. One such preferred embodiment is shown in FIG. 9 wherein cleaning 
element 19 extends beyond each end of charge inducing member 2. 
With reference to the embodiment shown in FIGS. 8A and 8B, the cycles of 
repetitive substantially axial movement of cleaning element 19 differ 
from, i.e., are nonintegral or nonsynchronized with the rotational cycles 
of charging roller 2. Preferably, the repetition rate of substantially 
axial movement of cleaning element 19 is greater than the cycles of 
rotation of charging roller 2. In a more preferred aspect of the 
invention, about one revolution of charging roller 2 corresponds to from 
about 1.5 to about 3.5 cycles of substantially axial reciprocal movement 
of cleaning element 19, most preferably 2.5 cycles of axial reciprocal 
movement of cleaning element 19. 
It is also a preferred aspect of the invention that the speed of movement 
of the cleaning element in one substantially axial direction is greater 
than that in the opposite direction, preferably from 1.5 to 2 times. In 
this way, more effective cleaning can be obtained, depending on the 
particular circumstances. 
We have observed that as the cleaning element rotates while in contact with 
rotating charging roller, vibrations can be induced in the photoconductive 
drum which may adversely affect the reproductions, as by causing blurred 
images. The embodiment of the present invention shown in FIG. 10, which is 
a variation of the embodiment shown in FIGS. 8A and 8B, avoids the 
generation of vibration in photoconductive drum 1 by virtue of clutch 
mechanism 24. Elements in FIG. 10 similar in function to those in FIG. 8A 
bear similar reference numerals. In accordance with the FIG. 10 embodiment 
of the invention, clutch 24, preferably an electromagnetic clutch, is 
positioned between photoconductive drum 1 and cam 11. Electromagnetic 
clutch 24 disengages cam 11 from photoconductive drum 1 so that cleaning 
element 19 does not reciprocate linealy during sensitive phases of the 
reproduction process, such as exposure of the photoconductive drum 1, 
development of the latent electrostatic image and transfer of the 
developed image. As in the FIG. 8A embodiment, the movement of cleaning 
element 19 is determined by the design of circumferential groove 18 in cam 
11. 
Also shown in FIG. 10 is a basic microprocessor 30 comprising CPU 31, ROM 
21 having a suitable program enabling cleaning element 11 to reciprocate 
linearly only during non-sensitive phases of development, RAM 33 which 
stores the input data from CPU 31, timer 34, and I/O 35. ROM 32 is 
preferably programmed so that the cleaning element 19 reciprocates only 
during the time that photoconductive drum 1 is not being exposed. Also 
shown is start button 36, positioned on an operations panel (not shown), 
for transmitting an initiation signal to controller 30. The operations 
panel may also contain means for displaying and selecting paper size, 
brightness or toner density, enlargement, reduction, color, number of 
sides reproduced, number of copies, and means for displaying instructions 
and troubleshooting information. 
In operation, when button 36 is depressed, a signal is sent to controller 
30, together with data from selections on the operations panel, such as 
paper size and toner density. Controller 30 then outputs a signal to drive 
the motor (not shown) of photoconductive drum 1 and signals to drive the 
other elements of the apparatus, including signals to light the apparatus 
panel (not shown). Controller 30 also generates an output signal to engage 
cam 11 to photoconductive drum 1. In the embodiment depicted in FIG. 10, a 
voltage source (not shown) generates a potential, for example of -500 
volts, which passes through conductive spring 12, and conductive bearing 
17 to conductive core 15 of charging roller 2. 
FIGS. 11A and 11B show signal timing charts illustrating operation of the 
embodiment of FIG. 10. Cam 11 is selectively decoupled from 
photoconductive drum 1 during exposure (FIG. 11A) and transfer (FIG. 11B) 
to avoid blurred reproductions due to vibrations caused by lineal 
reciprocation of cleaning element 19. As shown in FIGS. 11A and 11B, 
electromagnetic clutch 20 is disengaged, thereby decoupling cam 11 from 
photoconductive drum 1 at t2 prior to the initiation of exposure or 
transfer at t1. Exposure and transfer are completed after time T. 
Electromagnetic clutch 20 is subsequently engaged, thereby coupling cam 11 
to photoconductive drum 1 and resuming reciprocation of cleaning element 
19, subsequently at time t3. Thus, electromagnetic clutch periodically 
disengages and engages, as shown in second and third cycles, to decouple 
cam 11 and, hence, prevent lineal reciprocation of cleaning element 19 
during sensitive phases of operation, thereby avoiding blurred 
reproductions due to induced vibrations. 
FIG. 12 shows another embodiment of the present invention designed to avoid 
blurred reproductions due to vibrations induced in the photoconductive 
drum by lineal reciprocation of the cleaning element in contact with the 
charging roller during sensitive phases of rotation of the photosensitive 
drum. As seen in FIG. 12, the patterned circumferential groove 18 in cam 
11 is designed with a relatively straight segment S. With reference to 
FIGS. 10 and 12, it should be apparent that while leg 21b is slidably 
engaged in straight segment S of circumferential groove 18, holder 21 and, 
consequently, cleaning element 19, do not reciprocate linearly. This 
elegantly simple technique eliminates the need for an electromagnetic 
clutch 24 and, advantageously, ceases lineal reciprocation of cleaning 
element 19 during sensitive phases of the reproduction process, such as 
exposure, development, and transfer. 
In a preferred embodiment of the present invention, the means for 
establishing relative lineal movement between the cleaning element and 
charge inducing member comprises two separate elements such as motors, one 
motor coupled to the charge inducing member and the other connected to the 
cleaning element. For example, one motor is coupled to a charging roller 
for inducing rotational movement, and a separate motor connected to a 
cleaning element for inducing reciprocal lineal movement. The provision of 
two separate motors affords the advantage of controlling nonintegral or 
nonsynchronized movement of the charging roller and cleaning element. 
Thus, the rate at which the cleaning element reciprocates linealy can be 
controlled in relation to the rate at which the charging roller rotates. 
Nonsynchronized or nonintegral lineal reciprocation and rotation enables 
more efficient cleaning of the charging roller by the cleaning element, as 
by removing deeply embedded toner or other contaminants. Preferably, for 
each revolution of the charging roller, the cleaning element is 
reciprocated linearly about 1 1/2 to about 2 1/2 strokes, but preferably 
about 2 1/2 strokes or thrusts of the cleaning element per revolution of 
the charging roller. In addition, it is preferred to move the cleaning 
element at different velocities in opposite directions. This additional 
flexibility enables cleaning in only one lineal direction when desirable 
under the particular circumstances. 
One preferred embodiment wherein means are provided for nonsynchronized 
lineal reciprocation of the cleaning element and rotation of the charging 
roller is shown in FIG. 13 wherein motor 34 effects reciprocal movement of 
cleaning element 19 in a substantially axial direction, and motor 37 
effects rotational movement of charging roller 2. Preferably, the length 
of cleaning element 19 is greater than the length L of the image forming 
portion of charging roller 2, i.e., the portion of charging roller 2 that 
directly contacts and charges the image forming portion of the 
photoconductive drum (not shown). 
Charging roller 2 is similar in structure to that shown in FIG. 2A in that 
it comprises a conductive metal core rod 15, and an intermediate layer 
(not shown in FIG. 13) of an elastomeric material having higher resiliency 
than the elastomeric material of the outer surface layer. The outer 
surface layer 16 preferably has a thickness ranging from about 7 .mu.m to 
about 13.4 .mu.m. In a preferred aspect of this embodiment, the 
intermediate layer is an epichlorohydron rubber and the surface layer 16 
is a material comprising an epichlorohydron rubber and a fluorine 
compound, such as copolymer of fluoro-olefin and hydrocarbon vinylether. 
With continued reference to FIG. 13, bracket 31 is affixed to the outer 
surface of cleaning element 19. Leg 32 of bracket 31 slidably engages 
circumferential groove 33a in cam 33 connected to motor 34. Charging 
roller 2 is mounted on conductive bearings 17 via core 15 which is 
connected to gear 35 that, in turn, engages driving gear 36 driven by 
motor 37. Thus, charging roller 2 is driven rotationally by motor 37. 
Motor 34, which operates independent of motor 37, can be programmed to 
advantageously operate during appropriate nonsensitive phases of the 
reproduction process to reciprocate cleaning element 19 linealy and to be 
nonoperational during sensitive phases of the reproduction process, such 
as exposure, development and transfer. 
The embodiment of the present invention, shown in FIG. 14, is similar to 
the embodiment shown in FIG. 13, and, therefore, similar elements are 
represented by similar reference numerals. The FIG. 14 embodiment differs 
from the FIG. 13 embodiment in that cam 33 containing circumferential 
groove 33a is replaced with cam 43 having a surface pattern 43a which is 
traced by leg 42 of bracket 31. Leg 42 is urged against surface pattern 
43a by spring 41. 
In the FIG. 13 and FIG. 14 embodiments, S represents the distance travelled 
by leg 32 or leg 42, respectively, to effect one thrust or one half of a 
lineal reciprocation of cleaning element 19. With reference to FIGS. 13 
and 14, the velocity of cleaning element 19 is determined by the design of 
circumferential groove 33a (FIG. 13) or the shape of cam surface 43a (FIG. 
14). Therefore, circumferential groove 33a (FIG. 13) and cam surface 43a 
(FIG. 14) can be designed so that cleaning element 19 moves slower in one 
reciprocating direction than in the opposite reciprocating direction for 
highly effective cleaning. 
Thus, separate motors are advantageously employed to effect rotation of the 
charging roller and lineal reciprocation of the cleaning element. During 
cleaning, relative rotational and lineal movement occurs between the 
charging roller and cleaning element, thereby effectively dislodging toner 
and other contaminants from the irregular surface of the charging roller. 
However, in operation, when electric poser is supplied to the charging 
roller to charge the photoconductive drum, static electricity is generated 
with attracts toner and other contaminants from the cleaning element to 
the charging roller because the cleaning element is in contact with the 
charging roller. Accordingly, a preferred variation of the embodiments 
shown in FIGS. 13 and 14 is shown in FIG. 15A which further includes means 
to move the charging roller 2 from a position in contact with the 
photoconductive drum 1 to effect charging thereof, and to a second 
position out of contact with photoconductive drum 1 but in contact with 
the cleaning element 19 at which time relative lineal and rotational 
movement is established therebetween to effect cleaning. This preferred 
embodiment advantageously avoids inducing vibrations in photoconductive 
drum 1 and, thereby, avoids blurred reproductions. 
Such preferred embodiment shown in FIG. 15A can be employed with the FIGS. 
13 and 14 embodiments. With reference to FIGS. 13, 14 and 15A, charging 
roller 2 is mounted via rod 15 to conductive bearing 17, which is 
connected to power supply 20 via conductive spring 12 fixed at 40. Arm 23, 
pivoted at 24, is linked at one end to spring 25 and at its other end to 
conductive bearing 17 via rod 15. Mechanism 10 pivots charging roller 2 
selectively into contact with the photoconductive drum 1 for charging 
(shown in FIG. 15C), or out of contact with photoconductive drum 1 and 
into contact with cleaning element 19 (shown in FIG. 15B) and into 
engagement with gear 35 driven via gear 36 by motor 37 to effect 
rotational movement of charging roller 2. At the same time, motor 34 
reciprocates cleaning element 19 in a substantially axial direction so 
that both relative rotational and relative lineal movement is established 
between charging roller 2 and cleaning element 19 to effectively remove 
toner and other contaminants from the irregular surface of charging roller 
2. Moreover, such cleaning is effected without inducing vibrations in 
photoconductive drum 1, thereby avoiding blurred images. 
In operation, when solenoid 26 is switched on, rod 26a withdraws and 
charging roller 2 is brought into contact with photoconductive drum 1 as 
shown in FIG. 15C and by phantom lines in FIG. 15A. When solenoid 26 is 
switched off, movable rod 26a extends thereby moving charging roller 2 out 
of contact with photoconductive drum 1 and into contact with cleaning 
element 22 (FIG. 15B) which linealy reciprocates in guides 28 and 29 
driven by motor 34. Advantageously, when power is supplied to charging 
roller 2, it is not in contact with cleaning element 19, thereby avoiding 
the transfer of toner and other contaminants back to charging roller 2 
from cleaning element 19 due to static electricity. Another advantage of 
this embodiment is that the motor 34 is not always on thereby extending 
the life of the components as well as down time on the machine. 
Advantageously, the rotational movement of charging roller 2 is 
nonsynchronized with respect to the reciprocating lineal movement of 
cleaning element 19. Thus, one rotation of charging roller 2 does not 
correspond to one complete lineal reciprocation of cleaning element 19. 
Preferably, for every complete revolution of charging roller 2, cleaning 
element 19 reciprocates 1 to 4 times, preferably twice. 
As in other embodiments, it is preferred that cleaning element 19 has a 
length greater than the length of charging roller 2. Preferably, at least 
one end of the cleaning element 19 extends beyond one end of charging 
roller 2. In the embodiments shown, each end of cleaning element 19 
extends beyond each end of charging roller 2. In this way, the entire 
charging portion of charging roller 2 is freed from toner and other 
contaminants. Thus, as a result of the nonsynchronized movement of the 
charging roller 2 with respect to cleaning element 19, and the relative 
rotational and reciprocal motion established therebetween, the same 
portion of charging roller 2 is not always cleaned by cleaning element 19 
and the entire charging portion of charging roller 2 is effectively 
cleaned. Alternatively, however, the length of the cleaning element may be 
the same, or even less, than that of charging roller 2, provided the 
thrust of the cleaning element is sufficient to cover at least the region 
P of the surface of the roller, as shown in FIG. 14A, corresponding to the 
image forming region of the photoconductive drum 1. 
It is also possible to replace both motor 34 and 37 with a single motor and 
a transmission between the motor and charging roller 2 of cleaning element 
22 to effect similar results. One having ordinary skill in the art would 
recognize that the present invention employing nonsynchronized or 
independent rotational and lineal reciprocating movements, and means to 
move a charge inducing member into and out of contact with a charge 
receiving member, is not confined to the embodiments shown in FIGS. 13, 
14, 15A, 15B and 15C. Rather, the present invention encompasses all 
variations of that basic concept. 
FIG. 16 is a block diagram showing operation of the FIG. 15A embodiment of 
the present invention. Shown in FIG. 16 are microcomputer 50 which 
controls solenoid 10, motor 37 and motor 34. FIG. 7 is a flow chart 
showing the control flow of the microcomputer 50. Upon engaging the start 
button (not shown), microcomputer 50 causes photoconductive drum 1 to 
rotate, solenoid mechanism 10 to move charging roller 2 into and out of 
contact with photoconductive drum 1, and motors 34 and 37 to operate 
according to the prescribed program described in FIG. 17. 
With reference now to FIG. 17 and the timing charge shown in FIG. 18, after 
time t1, solenoid 26 is switched on (Block 2) and charging roller 2 is 
moved into contact with photoconductive drum 1. Next, photoconductive drum 
1 rotates (Block 3). Charging roller 1 then charges the surface of the 
photoconductive drum (Block 4). After time A, photoconductive drum is 
turned off (Block 5), wherein time (A)=t3-t2. The charging roller is then 
turned off (Block 6), followed by solenoid mechanism 26 being switched off 
(Block 7). Next, motor 37 (Block 8) and motor 34 (Block 9) are switched 
on, thereby initiating cleaning. After time t3, (Block 10), 
photoconductive drum 1, motor 37 and motor 34 are turned off (Blocks 11, 
12, 13, respectively). With reference to FIG. 18, since t1 is greater than 
t2, the life of the charging roller is extended, thereby providing an 
additional advantage. 
Another embodiment of the present invention is shown in FIGS. 19A-D, 
wherein charging roller 2 is shown in contact with cleaning element 19, 
the arrow thereon indicating the directions of reciprocating movement 
effected by an assemblage of gears to which cleaning element 19 is 
connected. The assemblage of gears comprises swing lever 41 and swing arm 
31 having a fixed pivot point at 81, gear 61 coupled to eccentric swing 
cam 51, and driving gear 71 driven by a motor (not shown) about shaft 91. 
As best seen in FIGS. 19C and D, swing cam 51 rotates about a fixed pivot 
point and, since it is entrapped within swing arm 41, causes swing arm 41 
to oscillate. Thus, linkage 3 functions as an oscillatory to linear 
translator. 
There accordingly has been described unique mechanisms and methodology for 
cleaning a charging roller of various debris and contamination that tends 
to adhere to it, by contacting a cleaning element to the roller and 
imparting lineal as well as rotary motion to one, the other or both the 
roller and element. As a result, there is considerable improvement in the 
ability of the cleaning element to remove debris from the surface of the 
roller, particularly in the surface crevices, and the like, as shown in 
FIG. 6B. In the environment of an electrophotographic apparatus wherein 
the roller is a contact charging element for a photoconductive drum, 
cleaning of the charging roller is inhibited during sensitive portions of 
a photocopy cycle. 
The foregoing embodiments are merely exemplary and not to be construed as 
limiting the basic concept of effecting relative lineal movement between 
charge inducing and cleaning element in a variety of electrostatic type 
apparatuses including, but not limited to, copiers, printers, facsimile 
machines, etc. Moreover, while charging rollers and photoconductive drums 
have been exemplified, the invention is not so limited, and can easily be 
applied to other shapes, e.g., photoconductive belts.