GB2362606A

GB2362606A - Electrophotographic component cleaning apparatus

Info

Publication number: GB2362606A
Application number: GB0120308A
Authority: GB
Inventors: Darius Boockholdt; Howard G Hooper; Quintin T Phillips
Original assignee: Hewlett Packard Co
Current assignee: HP Inc
Priority date: 1998-08-28
Filing date: 1998-08-28
Publication date: 2001-11-28
Anticipated expiration: 2018-08-28
Also published as: GB2362606B; GB0120308D0

Abstract

An electrophotographic component cleaning apparatus includes a cleaning roller (202) which is installed into the printer in place of the transfer roller (14). A reservoir (203) pivotally attached to the shaft (201) of the cleaning roller (202) contains cleaning fluid which is absorbed into the cleaning roller. Movement of the cleaning roller (202) over the surface of the photoconductor drum (3) results in the removal of contaminants. In a third embodiment of the electrophotographic component cleaning apparatus for use with an electrophotographic print cartridge (9), the electrophotographic print cartridge (9) is mounted into a stand (400) with the drum (3) in contact with the cleaning roller (202). Movement of the cleaning roller (202) over the surface of the photoconductor drum (3) results in the removal of contaminants.

Description

t.

2362606 1 ELECTROPHOTOGRAPHIC COMPONENT CLEANING APPARATUS FIELD OF THE INVENTION

The present invention relates generally to electrophotographic image formation and, more particularly, to the cleaning of electrophotographic components used in electrophotographic image formation.

BACKGROUND OF THE INVENTION

Photoconductors are used in electrophotographic imaging devices for the formation and subsequent development of the latent electrostatic image.

Photoconductors include photoconductor drums and photoconductor belts. As a result of the electrophotographic imaging process, contaminants, including such things as paper fibers, toner constituents, paper filler materials (magnesium silicate, calcium carbonate, titanium dioxide, etc.), and plastic materials from transparencies or coated print media can accumulate on the surface of the photoconductor. In addition, the surfaces of other components in the electrostatic image forming process, such as transfer belts and transfer drums, can also become contaminated from the electrophotographic image forming process. Because the print media characteristics vary widely between different media types, there is great uncertainty in the type and level of contaminants to which the photoconductor will be exposed.

These contaminants can cause print quality defects and can result in the degradation of print quality. Typically, those components used in the electrostatic image forming process which are in direct contact with print media are the most susceptible to contamination. However, it is possible that contaminants transferred to components that are not directly in contact with print media can result in print quality defects. When contaminant levels on the surface of the photoconductor are sufficiently high, the contaminants interfere with the formation of electrostatic images resulting in print defects. For example, a contaminant film on the surface of the photoconductor may prevent proper charging of the photoconductor or discharging of the photoconductor for the formation of the latent electrostatic image. As another example, paper p 2 fibers may accumulate over time between the photoconductor and a cleaning blade so that residual toner on the surface of the photoconductor is not effectively removed. Contaminants can also result in damage to electrophotographic components. For example, contact with contaminants over time can result in increased wear of the photoconductor, which in turn results in the degradation of print quality.

Prior art attempts to clean electrophotographic components have generally been implemented within the image forming device, such as an electrophotographic printer or an electrophotographic copier. In addition, in the prior art, cleaning devices have been implemented within electrophotographic cartridges used in printers. However, the mechanical structure required to implement the cleaning in the image forming device or the cartridge adds considerably to the cost of the solution. Furthermore, with "in-process" cleaning devices, the cleaning process is occurring as the electrophotographic process is performed. Because the cleaning process occurs continuously as the electrophotographic process is performed, more wear than necessary occurs on the electrophotographic components. A need exists for an electrophotographic component cleaning device that is less expensive to implement and results in less wear of the electro photographic components than the current solutions.

SUMMARY OF THE INVENTION

To fill this need, a low cost, reduced wear apparatus for cleaning an electrophotographic component has been developed.

Thus, in accordance with a first aspect of the present invention there is provided an apparatus as defined in claim 1 In use of the apparatus, relative motion between the electrophotographic component and the cleaning roller results in removal of contaminants from the electrophotographic component.

In accordance with a second aspect of the present invention there is provided an apparatus as defined in claim 5.

1 3 When component cleaning is desired the member is mounted onto the electrophotographic imaging device, and the pad is in contact with the. electrophotographic component. Relative motion between the electrophotographic component and the pad results in removal of contaminants from the 5 electrophotographic component.

DESCRIPTION OF THE DRAWINGS

A more thorough understanding of the invention may be had from the consideration of the following detailed description taken in conjunction with the accompanying drawings, in which:

Figure 1 shows a schematic cross section of a typical electrophotographic printer.

Figure 2a is a schematic cross section showing an electrophotographic print cartridge and a first embodiment of the electrophotographic component cleaning apparatus.

Figure 2b shows a perspective view of the first embodiment of the electrophotographic component cleaning apparatus.

Figure 3a is a schematic cross section of a second embodiment of the electrophotographic component cleaning apparatus.

Figure 3b is a schematic cross section of an alternative implementation of the second embodiment of the electrophotographic component cleaning apparatus.

Figure 4 shows a schematic cross section of a third embodiment of the electrophotographic component cleaning apparatus.

1 4 DETAILED -DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is not limited to the specific exemplary embodiments illustrated herein. Although the embodiments of the electrophotographic component cleaning apparatus will be discussed in the context of a monochrome electrophotographic printer using a replaceable electrophotographic cartridge, one of ordinary skill in the art will recognize by understanding this specification that the electrophotographic component cleaning apparatus has applicability for both color and monochrome electro photographic image forming systems including copiers and printers. Furthermore, although the embodiments of the electrophotographic component cleaning apparatus will be discussed in the context of a monochrome electrophotographic printer using a photoconductor drum, one of ordinary skill in the art will recognize by understanding this specification that the embodiments of electrophotographic component cleaning apparatus could be used with other types of el ectro photo graphic components, such as a photoconductor belt, transfer belt, or a transfer drum.

Referring to Figure 1, shown is a simplified schematic representation of the cross section of an electrophotographic printer 1. Charge roller 2 is used to charge the surface of photoconductor drum 3 to a predetermined voltage. A 1 1 laser diode in a laser scanner 23 emits a laser beam 4 which is pulsed on and off as it is swept across the surface of photoconductor drum 3 by the laser scanner to selectively discharge the surface of the photoconductor drum 3. Photoconductor drum 3 rotates in the clockwise direction as shown by the arrow 5. Developer 6 is used to develop the latent electrostatic image residing on the surface of photoconductor drum 3 after the surface voltage of the photoconductor drum 3 has been selectively discharged. Toner 7 which is stored in the toner hopper 8 of electrophotographic print cartridge 9 moves from locations within the toner hopper 8 to the developer 6. A magnet (not shown) located within the developer 6 magnetically attracts the toner to the surface of the developer 6. As the developer 6 rotates in the counterclockwise direction, the toner on the surface of the developer 6, located opposite the areas on the surface of photoconductor drum 3 which are discharged, is moved by the application of a potential to the developer 6 across the gap between the surface of the photoconductor drum 3 and the surface of the developer 6 to develop the latent electrostatic image.

Print media 10 is loaded from paper tray 11 by pickup roller 12 into the paper path of the electrophotographic printer 1. Print media 10 moves through the drive rollers 13 so that the arrival of the leading edge of print media 10 below photoconductor drum 3 is synchronized with the rotation of the region on the surface of photoconductor drum 3 having a latent electrostatic image corresponding to the leading edge of print media 10. As the photoconductor drum 3 continues to rotate in the clockwise direction, the surface of the photoconductor drum 3, having toner adhered to it in the discharged areas, contacts the print media 10 which has been charged by transfer roller 14 so that it attracts the toner particles away from the surface of the photoconductor drum 3 and onto the surface of the print media 10. The transfer of toner particles from the surface of photoconductor drum 3 to the surface of the print media 10 does not occur with one hundred percent efficiency and therefore some toner particles remain on the surface of photoconductor drum 3. As photoconductor drum 3 continues to rotate, toner particles which remain adhered to its surface 6 are removed by cleaning blade 15 and deposited in toner waste hopper 16.

As the print media 10 moves in the paper path past photoconductor drum 3, conveyer belt 17 delivers the print media 10 to the f user assembly 18. In the f user assembly 18, heat is applied so that the toner particles are fused to the print media 10. Output rollers 19 push the print media 10 into the output tray 20 after it exits the f user assembly 18. Further details on electrophotographic processes can be found in the text "The Physics and Technology of Xerographic Processes", by Edgar M. Williams, 1984, a Wiley Interscience Publication of John Wiley & Sons, the disclosure of which is incorporated by reference herein.

A high voltage power supply 21 supplies the bias voltages and bias currents to the charge roller 2, transfer roller 14, and developer 6 necessary for operation of the electrophotographic processes. The charge roller 2 is driven with a sinusoidal voltage waveform having a negative D.C. offset. The amplitude and frequency of the sinusoid are selected so that the surface of photoconductor drum 3 on which charge will be deposited is uniformly charged at approximately the value of the D.C. offset. The transfer roller 14 is driven with positive DC voltage during the transfer operation. The developer 6 is driven with a sinusoid voltage waveform having a variable negative D.C. offset.

Engine controller 22 generates the timing and control signals necessary to control the components in electrophotographic printer 1 to perform the electrophotographic printing process. These timing and control signals include signals which control the amplitude and timing of the voltages supplied by high voltage power supply 21 and the movement of the various rollers in the paper path. In addition, engine controller 22 provides the serial stream of binary print data to the laser scanner 23 for controlling the pulsing of laser beam 4.

As the result of printing on a number of units of print media 10 using electro photographic printer 1, contaminants accu mulate on the surface of photoconductor drum 3. As previously mentioned, these contaminants can include fibers from the print media 10, fillers used in print media 10, and constituents of the toner 7. Accumulation of these contaminants prevents the 7 proper operation of the electrophotographic process.

Shown in Figures 2a and 2b is a first embodiment of an electrophotographic component cleaning apparatus. Although this embodiment of the electrophotographic component cleaning apparatus is used within electrophotographic printer 1, for the purposes of illustrative clarity, only the first embodiment of the electrophotographic component cleaning apparatus and the electrophotographic print cartridge 9 are shown in Figure la. In the first embodiment of the electrophotographic component cleaning apparatus, a cleaning roller 200 replaces transfer roller 14 in electrophotographic printer 1. The cleaning roller 200 is designed so that it can be inserted into electrophotographic printer 1 after removal of transfer roller 14. As shown in Figure 3b, the cleaning roller 200 includes a shaft 201 made of a rigid material, such as metal or plastic, surrounded by a cylinder 202 formed of a fluid absorbing material, such as an open cell foam, suitable for cleaning the surface of a photoconductor. A fluid reservoir 203 is pivotally mounted to the shaft 201 so that the fluid reservoir stays in position beneath cleaning roller 200 as it rotates during the cleaning operation. Fluid reservoir 203 is filled with a cleaning fluid to enhance the cleaning operation. Alternatively, cleaning roller 200 may be saturated with cleaning fluid prior to installation in electrophotographic printer 1. For this option the fluid reservoir 203 would not be included in the electrophotographic component cleaning apparatus.

As the cleaning roller 200 rotates, cleaning fluid absorbed into the 8 cylinder 202 of porous material of cleaning roller 200 contacts the surface of photoconductor drum 3 and assists in the removal of contaminants. The cleaning roller 200 is of a larger diameter than transfer roller 14 so that it is compressed against the surface of photoconductor drum 3 to provide a scrubbing action that further assists in the removal of contaminants. The compressive force used to load the cleaning roller 200 is supplied by the springs 24 used to force transfer roller 14 against the surface of photoconductor drum 3 and by the top cover of electro photographic printer 1 applying force to the electrophotographic print cartridge 9 housing photoconductor drum 3. When the cleaning operation is performed upon photoconductor drum 3, engine controller 22 sets the output voltages of high voltage power supply 21 to zero and turns the printer gear train drive motor on to rotate photoconductor drum 3.

In electrophotographic printer 1, the transfer roller 14 is gear driven by photoconductor drum 3. A first gear 204 attached on shaft 201 of cleaning roller 200 allows photoconductor drum 3 to drive cleaning roller 200. This first gear 204 meshes with a second gear 205 on photoconductor drum 3. Photoconductor drum gear 206 meshes with a gear in the gear train of electrophotographic printer 1. The second gear 205 on photoconductor drum 3 is driven by the photoconductor drum drive gear in the gear train of electrophotographic printer 1. In electrophotographic printer 1, the ratio of the gearing between transfer roller 14 and photoconductor drum 3 is selected so that the rotational velocities at the surface of transfer roller 14 and at the surface of photoconductor drum 3 are substantially equal. With the cleaning roller 200 of larger diameter than the transfer roller 14, and by designing first gear 204 to have the same gear ratio with second gear 205 as exists with transfer roller 14 in electrophotographic printer 1, the velocity at the surface of cleaning roller 200 is greater than at the surface of photoconductor drum 3. As a result, cleaning roller 200 is in sliding contact with photoconductor drum 3. This sliding contact enhances the cleaning action relative to the case in which the cleaning roller 200 rolls over the surface of photoconductor drum 3.

Shown in Figure 3a and Figure 3b is a second embodiment of an 9 electrophotographic component cleaning apparatus. In the second embodiment of the electrophotographic component cleaning apparatus, a cleaning pad 300 is inserted through the slot in the electrophotographic print cartridge 9 through which the laser beam passes. The material used for the cleaning pad 300 is selected using considerations similar to those used to select the material for the second embodiment of the electrophotographic cleaning apparatus. There are several alternatives available to load the cleaning pad 300 against the surface of photoconductor drum 3 for cleaning. The first alternative, shown in Figure 3a, uses hooked flanges 301 on cleaning pad holder 302 which lock the cleaning pad 300 in place so that the cleaning pad is compressed against the surface of photoconductor drum 3. The cleaning pad is released from contact with the surface of photoconductor drum 3 by flexing the sides of cleaning pad holder 302 inward. The second alternative, shown in Figure 3b, uses a sloped surface 303 on the cleaning pad holder 302 which is forced against the top cover of electrophotographic printer 1. The interference between the top cover and the cleaning pad holder 302 compresses the cleaning pad 300 against the surface of photoconductor drum 3. Cleaning pad 300 may be soaked in cleaning fluid prior to installation into electrophotographic print c artridge 9.

Shown in Figure 4 is a third embodiment of an electrophotographic component cleaning apparatus. In the third embodiment, a stand 400 is used to mount the electrophotographic print cartridge for cleaning. The stand 400 serves to hold the electro photographic print cartridge substantially stationary as cleaning roller 200 slides over the surface of photoconductor drum 3. The term "substantially stationary" in this context means that although the cartridge may undergo some movement during cleaning, there is no significant displacement of the cartridge. The stand 400 is hinged at 403 to allow insertion of electrophotographic print cartridge 9 into the stand 400 for cleaning. Included in stand 400 is a motor and a gear train (not shown) used to drive the photoconductor drum 3 and the cleaning roller 200. Alternatively, the gear train may be driven manually using a hand crank. The stand 400 serves as a substitute for the chassis of electrophotographic printer 1 to hold electrophotographic print cartridge substantially stationary while rotating photoconductor drum 3 and cleaning roller 200. Although some displacement of the cartridge is allowed as the gear train drives photoconductor drum 3, the displacement must be sufficiently small so that cleaning roller 200 maintains contact with the surface of photoconductor drum 3. A fluid reservoir 401 is used to hold a cleaning fluid. As was the case for the previous embodiments of the electrophotographic component cleaning apparatus, cleaning roller 200 maybe constructed from a fluid absorbing material such as felt or sponge. The cleaning fluid absorbed into thecleaning roller 200 cleans the surface of photoconductor drum 3 as it rotates. A cleaning brush 402 removes contaminants accumulated on the surface of cleaning roller 200 to improve the cleaning efficiency. With the cleaning brush 402, each rotation of cleaning roller 200 presents a clean surface to photoconductor drum 3.

Similar to the first embodiment of the electrophotographic component cleaning apparatus, the cleaning roller 200 could be geared so that it is driven at a higher rotational rate than the photoconductor drum 3 to establish sliding contact with the surface of photoconductor drum 3. Alternatively, the stand 400 may be geared so that cleaning roller 200 rotates in the opposite direction of photoconductor drum 3. This arrangement would provide additional cleaning action.

Although several embodiments of the invention have been illustrated, and their forms described, it is readily apparent to those of ordinary skill in the art that various modifications may be made therein without departing from the scope of the appended claims.

Claims

CLAIMS:

An apparatus for cleaning an electrophotographic component of an electrophotographic imaging device, comprising: a cleaning roller formed from a fluid-absorbi"ng, resilient material and having a longitudinal axis, said cleaning roller being arranged for compressing against said electrophotographic component, such that said material is in contact therewith.

2.An apparatus as claimed in claim 1, further comprising:

rigid shaft coincident with said longitudinal axis; first gear mounted on said rigid shaft with said electrophotographic component including a photoconductor drum having a second gear for meshing with said first gear to rotate said cleaning roller; and a reservoir pivotally mounted on said rigid shaft, said reservoir having an interior region partially enclosing said cleaning roller.

An apparatus as claimed in claim 2, wherein: said electrophotographic imaging device includes a removable transfer roller; and said cleaning roller is installed in said electrophotographic imaging device in substitution for said transfer roller.

An apparatus as claimed in claim 2, further comprising:

a stand having said reservoir mounted thereon, said stand being arranged for holding an electrophotographic print cartridge, including said photoconductor drum, substantially stationary during rotation of said cleaning roller; and a brush mounted in said interior region of said reservoir and contacting said cleaning roller, with said cleaning roller rotating in a direction opposite to that of said photoconductor drum.

1 12 5.

An apparatus for cleaning an electrophotographic component of an electrophotographic imaging device, comprising: a member having a channel and being arranged for removably mounting on said electrophotographic imaging device; and a pad formed of a fluid-absorbing, resilient material disposed in said channel and of sufficient size for said material to contact said electrophotographic component with said member mounted on said electrophotographic device.

6. An apparatus as claimed in claim 5, wherein:

said electrophotographic component includes a photoconductor drum incorporated within an electrophotographic print cartridge having an access slot for a laser beam, said pad being adapted for insertion into said access slot; and said member includes a pair of hooked flanges protruding from said member adjacent to the sides of said channel for insertion into said access slot to removably mount said member to said electrophotographic print cartridge so that said pad compresses against said photoconductor drum.

7. An apparatus as claimed in claim 6, wherein:

the materials forming said pad include felt; and said member includes a sloped surface located opposite said channel.

8. An apparatus for cleaning an electrophotographic component of an electrophotographic imaging device substantially as hereinbefore described with reference any one of Figures 2a, 2b, 3a, 3b or 4 of the accompanying drawings.