JP2010066652A - Cleaning unit and image forming apparatus provided with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cleaning unit which can effectively suppress image deletion by improving the polishing function for a surface of a photoreceptor by supplying sufficient toner to a rotary member for polishing with a simple composition and to provide an image forming apparatus with the cleaning unit. <P>SOLUTION: The cleaning unit 17 includes: a housing 17a for forming an exterior with an opening section facing a photoreceptor drum 14; a first rubbing roller 25 and a second rubbing roller 27 for eliminating the residual toner on the surface of the photoreceptor drum 14 and polishing the surface of the photoreceptor drum 14 using the residual toner by coming into a rubbing; and a cleaning blade 29 which is arranged on the downstream side of the second rubbing roller 27 in the rotating direction of the photoreceptor drum 14 for eliminating the residual toner on the surface of the photoreceptor drum 14. The first rubbing roller 25 which is made to trail and rotate and the second rubbing roller 27 which is made to counter rotate respectively to the photoreceptor drum 14 are arranged to come into contact with each other. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a cleaning device having a mechanism for polishing the surface of an image carrier using a rubbing roller, and in particular, a photoconductor when an amorphous silicon (hereinafter referred to as a-Si) type photoconductor is used as an image carrier. The present invention relates to a cleaning device capable of suppressing image flow on a surface and an image forming apparatus including the same.

  In recent years, an a-Si photosensitive drum has been widely used as an image carrier of an image forming apparatus using an electrophotographic process. The a-Si photoconductor drum has high hardness and excellent durability, and its characteristics as a photoconductor are hardly deteriorated even after long-term use. In addition, the image carrier is excellent in environmental safety.

  In an image forming apparatus using such an a-Si photosensitive drum, it is known that image flow tends to occur due to its characteristics. That is, when charging is performed using a charging device, ozone is generated by discharging of the charging device. The components in the air are decomposed by the ozone, and ion products such as NOx and SOx are generated. Since this ion product is water-soluble, it adheres to the photosensitive drum and enters into a roughness structure of about 0.1 μm on the surface of the photosensitive drum, so that it can be removed by a cleaning system used in a general-purpose machine. In addition, the resistance of the surface of the photosensitive drum is lowered by taking in moisture in the atmosphere. As a result, the lateral flow of the potential occurs at the edge portion of the electrostatic latent image formed on the surface of the photosensitive drum, and as a result, the image flow may occur.

  Conventionally, by putting a heater in the photoconductor drum, energy is given to release the moisture taken in by the ion products, and the resistance decrease on the surface of the photoconductor drum in a high-humidity environment is suppressed. ing. However, in such an apparatus, the number of parts for constituting the heater is increased, leading to an increase in cost and not preferable from the viewpoint of safety.

  In view of this, a method for removing ozone products by a system for polishing a photosensitive member by the interaction of polishing toner mixed with an abrasive and a polishing means (sliding roller and cleaning blade) without using a heater has been proposed. . According to this technique, even if the ion product as described above adheres to the surface of the photosensitive drum, it can be sufficiently removed.

Further, in Patent Document 1, a plurality of rotating members (rubbing rollers) for photoconductor polishing are disposed, the rotating directions of adjacent rotating members are reversed, and the rotating direction of the photoconductor is forward. An image forming apparatus with improved polishing performance on the surface of the photoconductor is obtained by rotating the rotating member at a speed higher than that of the photoconductor, and rotating the rotary member rotating in the direction opposite to the rotation direction of the photoconductor at a speed slower than that of the photoconductor. It is disclosed.
JP 2004-361775 A

  According to the method of Patent Document 1, although the polishing performance on the surface of the photoreceptor is improved by using a plurality of rotating members, the toner containing the abrasive cannot be sufficiently adhered to each rotating member. In the configuration of Patent Document 1, a scraper for attaching toner to the rotating member is used. However, this configuration has a demerit that the number of parts increases, and there is still room for further improvement.

  In view of the above problems, the present invention provides a cleaning device capable of effectively suppressing image flow by improving the polishing performance of the surface of a photoreceptor by supplying sufficient toner to a polishing rotating member with a simple configuration. An object of the present invention is to provide an image forming apparatus including the same.

  In order to achieve the above object, the present invention comprises two rubbing surfaces that are pressed against the surface of the image carrier at a predetermined pressure, and the residual toner on the image carrier is adhered to the surface to polish the surface of the image carrier. A first rubbing roller positioned upstream of the image carrier in the moving direction rotates forward with respect to the moving direction of the image carrier; The second rubbing roller located on the downstream side in the moving direction of the image carrier is a cleaning device that rotates in the reverse direction with respect to the moving direction of the image carrier.

  According to the present invention, in the cleaning device configured as described above, the rotation speeds of the first and second rubbing rollers are equal.

  According to the present invention, in the cleaning device configured as described above, a rotational speed of the first rubbing roller is different from a moving speed of the image carrier.

  According to the present invention, in the cleaning device configured as described above, an outer diameter of the first rubbing roller is larger than that of the second rubbing roller.

  According to the present invention, in the cleaning device configured as described above, a pressing force of the second rubbing roller against the image carrier is smaller than that of the first rubbing roller.

  According to the present invention, in the cleaning device having the above-described configuration, a cleaning blade that is pressed against the surface of the image carrier with a predetermined pressure is provided downstream of the second rubbing roller in the moving direction of the image carrier. It is characterized by.

  The present invention also provides an image forming apparatus equipped with the cleaning device having the above-described configuration.

  According to the present invention, in the image forming apparatus having the above-described configuration, a charging member that charges the surface of the image carrier in a contact state or a non-contact state is provided downstream of the cleaning device in the moving direction of the image carrier. It is characterized by.

  According to the first configuration of the present invention, the residual toner weakly attached to the first rubbing roller on the upstream side with respect to the moving direction of the image carrier is first in the contact portion with the second rubbing roller on the downstream side. Pressed against the rubbing roller and the second rubbing roller. Therefore, the toner can be reliably attached to the first rubbing roller and the second rubbing roller without using another member such as a scraper.

  Further, according to the second configuration of the present invention, in the cleaning device of the first configuration, the first and second rubbing rollers are worn by equalizing the rotation speeds of the first and second rubbing rollers. It is possible to extend the life by suppressing the above.

  According to the third configuration of the present invention, in the cleaning device having the first or second configuration, the first rubbing roller has a rotational speed different from the moving speed of the image carrier, so The polishing performance can be improved by generating a polishing effect on the roller.

  Further, according to the fourth configuration of the present invention, in the cleaning device having any one of the first to third configurations, by making the outer diameter of the first rubbing roller larger than that of the second rubbing roller, The first rubbing roller is wider than the second rubbing roller in the width of the portion in contact with the image carrier. For this reason, the residual toner on the image carrier is likely to adhere to the first rubbing roller, and more toner can be adhered to the second rubbing roller. Further, every time the first rubbing roller makes one rotation, the second rubbing roller always comes into contact with the second rubbing roller at a different portion, so that the toner can be uniformly attached to the second rubbing roller.

  According to the fifth configuration of the invention, in the cleaning device having any one of the first to fourth configurations, the pressing force of the second rubbing roller against the image carrier is smaller than that of the first rubbing roller. By doing so, the shake of the image carrier by the second rubbing roller that rotates in the reverse direction with respect to the image carrier can be suppressed, and the occurrence of jitter can be suppressed.

  According to the sixth configuration of the present invention, in the cleaning device having any one of the first to fifth configurations, the cleaning blade that is pressed against the surface of the image carrier with a predetermined pressure is provided with the second rubbing roller. By providing it on the downstream side in the moving direction of the image carrier, the residual toner on the image carrier is almost peeled off by the second rubbing roller that rotates in reverse with respect to the image carrier, and the amount of toner that slips to the cleaning blade side is reduced. Decrease. This reduces the load on the cleaning blade and improves the cleaning performance. Further, it is possible to prevent dielectric breakdown of the image carrier due to frictional charging of the toner staying at the edge portion of the cleaning blade to cause discharge.

  Further, according to the seventh configuration of the present invention, by mounting the cleaning device having any one of the first to sixth configurations, the adhesion of the discharge product to the image carrier is suppressed, and the surface friction coefficient. The image forming apparatus can effectively suppress the rise and image flow.

  According to the eighth configuration of the invention, in the image forming apparatus having the seventh configuration, the surface of the image carrier is in contact with or not in contact with the downstream side in the moving direction of the image carrier relative to the cleaning device. By providing a charging member to be charged, adhesion of toner external additives to the charging member, which is a problem with the charging method using a contact type or a non-contact type charging member with a narrow gap with the image carrier, is effectively suppressed. An image forming apparatus that can be used.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing the overall configuration of an image forming apparatus equipped with a cleaning device of the present invention. As shown in FIG. 1, an image forming apparatus (in this case, a monochrome printer) 100 includes a sheet feeding cassette 2 that accommodates stacked sheets at the bottom of the main body. Above this paper feed cassette 2 is formed a paper transport path 4 extending substantially horizontally from the front of the main body (right side in FIG. 1) to the rear of the main body and further upward to reach the paper discharge unit 3 formed on the upper surface of the main body. A pickup roller 5, a feed roller 6, an intermediate conveyance roller 7, a registration roller pair 8, an image forming unit 9, a fixing unit 10, and a discharge roller pair 11 are arranged in this order along the paper conveyance path 4 from the upstream side. Has been.

  The paper feed cassette 2 is provided with a paper stacking plate 12 that is rotatably supported with respect to the paper feed cassette 2 by a rotation fulcrum 12a provided at the rear end in the paper transport direction. The sheet thus formed is pressed against the pickup roller 5. A retard roller 13 is disposed in front of the paper feed cassette 2 so as to be in pressure contact with the feed roller 6, and when a plurality of sheets are simultaneously fed by the pickup roller 5, the feed roller 6 and the retard roller 13 are used to roll the paper, and only the topmost sheet is conveyed.

  Then, the sheet fed by the feed roller 6 and the retard roller 13 is conveyed to the registration roller pair 8 by changing the conveyance direction to the rear of the apparatus by the intermediate conveyance roller 7, and the timing is adjusted by the registration roller pair 8. And conveyed to the image forming unit 9.

  The image forming unit 9 forms a predetermined toner image on a sheet by an electrophotographic process. The image forming unit 9 is a photosensitive drum 14 that is an image carrier rotatably supported in the clockwise direction in FIG. Above the charging drum 15, the developing device 16, the cleaning device 17, the transfer roller 18 disposed so as to face the photosensitive drum 14 across the sheet conveyance path 4, and the photosensitive drum 14. A toner container 20 for supplying toner to the developing device 16 as necessary is disposed above the developing device 16.

  For example, the photosensitive drum 14 is formed by laminating a photosensitive layer on an aluminum drum. As the photosensitive material for forming the photosensitive layer, an amorphous silicon photoreceptor or an organic photoreceptor (OPC photoreceptor) is used. As the charging device 15, a scorotron charging device using a corona discharge charger is used, and a metal shield case having a U-shaped cross section disposed so that the opening faces the photosensitive drum 14 is disposed inside. Corona wires and grids, which are discharge members made of tungsten, stainless steel, etc., are provided, and a predetermined charging bias is applied to the corona wires and grids to generate corona discharge and control the amount of electrons. As a result, the surface of the photosensitive drum 14 is uniformly charged with a predetermined polarity and potential.

  Next, the photosensitive drum 14 is exposed to light by a laser beam from a laser scanning unit (LSU) 19 to attenuate charging, and an electrostatic latent image based on image data input to the surface of the photosensitive drum 14 is formed. . Then, the developing device 16 attaches toner to the electrostatic latent image to form a toner image on the surface of the photosensitive drum 14. The toner image formed on the photosensitive drum 14 is transferred onto a sheet supplied to the nip portion (transfer position) between the photosensitive drum 14 and the transfer roller 18 by the transfer roller 18.

  The sheet on which the toner image is transferred is separated from the photosensitive drum 14 and conveyed toward the fixing unit 10. The fixing unit 10 is disposed on the downstream side of the image forming unit 9 in the sheet conveyance direction, and includes a heating roller 21 and a pressure roller 22 that is pressed against the heating roller 21. The sheet on which the toner image is transferred in the image forming unit 9 is heated and pressed by passing through the nip portion between the heating roller 21 and the pressure roller 22, and the toner image transferred to the sheet is fixed.

  The paper that has passed through the fixing unit 10 is discharged to the paper discharge unit 3 by the discharge roller pair 11. On the other hand, the toner remaining on the surface of the photosensitive drum 14 is removed by the cleaning device 17. The photosensitive drum 14 is neutralized by a neutralizing device (not shown) and then charged again by the charging device 15, and image formation is performed in the same manner. The configuration of the cleaning device 17 will be described later.

  FIG. 2 is an enlarged view of the image forming unit 9 in FIG. When the photosensitive drum 14 is an a-Si photosensitive member, for example, an a-Si photoconductive layer is formed on a conductive substrate, and an a-Si based SiC, SiN, SiO, SiON, SiCN, or the like is formed on the upper surface thereof. A surface protective layer made of an inorganic insulator or an inorganic semiconductor is laminated. The toner supplied from the developing device 16 is a toner containing an abrasive (hereinafter referred to as abrasive toner). The polishing toner not only adheres to the electrostatic latent image on the photosensitive drum 14 to form a toner image, but also polishes the surface of the photosensitive drum 14 using residual toner that has not been transferred by the transfer roller 18. Used to do.

  As a constitution of the abrasive toner, an abrasive such as silica, alumina, zirconia, titania or the like is attached to the surface using a binder resin as toner base particles. As a method for adhering the abrasive to the toner base particles, it may be electrostatically adsorbed, or the abrasive may be driven and held by applying a thermal / mechanical impact to the surface of the toner base particles. Good. The abrasive particles thus implanted may be configured not to be completely buried in the toner base particles but to protrude partially.

  The cleaning device 17 removes the residual toner on the surface of the photosensitive drum 14 and the housing 17a that forms an exterior having an opening toward the photosensitive drum 14, and slides the surface of the photosensitive drum 14 using the residual toner. The first rubbing roller 25 and the second rubbing roller 27 that are rubbed and polished are disposed on the downstream side of the second rubbing roller 27 with respect to the rotation direction of the photosensitive drum 14, and the residual toner on the surface of the photosensitive drum 14. And a cleaning blade 29 for removing water. Residual toner removed from the photosensitive drum 14 by the first rubbing roller 25, the second rubbing roller 27 and the cleaning blade 29 is collected by the conveying spiral 30.

  The first rubbing roller 25 and the second rubbing roller 27 are pressed against the photosensitive drum 14 with a predetermined pressure, and are rotatably supported on front and rear side plates (not shown) of the housing 17a. The first rubbing roller 25 is rotationally driven in the same direction (hereinafter referred to as trail rotation) on the contact surface with the photosensitive drum 14 by a driving means (not shown), and the second rubbing roller 27 is in contact with the photosensitive drum 14. The contact surface is rotationally driven in the opposite direction (hereinafter referred to as counter rotation). Examples of the first rubbing roller 25 and the second rubbing roller 27 include a structure in which a foam layer made of EPDM (ethylene-propylene-diene rubber) and having an Asuka C hardness of 55 ° is formed as a roller body around a metal shaft. It is done. The material of the roller body is not limited to EPDM, and other materials such as rubber or foamed rubber body may be used, and those having an Asuka C hardness of 10 to 90 ° are preferably used.

  On the downstream side of the second rubbing roller 27 with respect to the rotation direction of the photosensitive drum 14, a cleaning blade 29 is fixed to the housing 17 a while being in contact with the photosensitive drum 14. As the material of the cleaning blade 29, for example, polyurethane rubber having a JIS hardness of 60 to 80 ° is used, and the material, hardness and dimensions of the cleaning blade 22, the amount of biting into the photosensitive drum 14, the pressure contact force, etc. It is set as appropriate according to the 14 specifications.

  The present invention is characterized in that the first rubbing roller 25 that rotates with respect to the photosensitive drum 14 and the second rubbing roller 27 that rotates counterclockwise are arranged so as to contact each other. With this configuration, as shown in FIG. 3, the polishing toner T that has moved to the cleaning device 17 along with the rotation of the photosensitive drum 14 is first in the contact portion A between the photosensitive drum 14 and the first rubbing roller 25. It adheres weakly to the rubbing roller 25 and is pressed against the second rubbing roller 27 at the contact portion N between the first rubbing roller 25 and the second rubbing roller 27. Further, a part of the polishing toner T adheres weakly to the second rubbing roller 27 at the contact portion B between the photosensitive drum 14 and the second rubbing roller 27 and is pressed against the first rubbing roller 25 at the contact portion N. .

  Therefore, the polishing toner can be reliably attached to the first rubbing roller 25 and the second rubbing roller 27 without using another member such as a scraper, and the polishing performance can be improved. Further, since the increase in the surface friction coefficient of the photosensitive drum 14 is also suppressed, the cleaning blade 29 can be prevented from turning up.

  Further, since the second rubbing roller 27 on the downstream side is counter-rotating with respect to the photosensitive drum 14, toner remaining on the drum is almost peeled off by the second rubbing roller 27 and slips to the cleaning blade 29 side. The amount decreases. This reduces the load on the cleaning blade 29 and improves the cleaning performance. Further, it is possible to prevent a phenomenon in which the toner staying at the edge portion of the cleaning blade 29 is triboelectrically charged to cause discharge and cause dielectric breakdown of the photosensitive drum 14.

  The rotation speeds of the first rubbing roller 25 and the second rubbing roller 27 may be different or may be constant. When the rotation speeds are made equal, the wear of the first rubbing roller 25 and the second rubbing roller 27 can be suppressed to extend the life. Further, the rotation speed of the first rubbing roller 25 that rotates on the trail may be different from the rotation speed of the photosensitive drum 14. In this case, the polishing effect by the first rubbing roller 25 is also generated, and the polishing power can be increased. The rotational speeds of the first rubbing roller 25 and the second rubbing roller 27 may be set in consideration of the polishing force of the photosensitive drum 14 and the occurrence of jitter due to the rubbing load. The rotation speed of the first rubbing roller 25 is set to 0.5 to 1.5 times, preferably 1.1 to 1.3 times the rotation speed of the photosensitive drum 14. The rotation speed of the second rubbing roller 27 that rotates counter is set to 0.5 to 1.5 times, preferably 0.8 to 1.0 times the rotation speed of the photosensitive drum 14.

  The driving of the first rubbing roller 25 and the second rubbing roller 27 is not particularly limited. For example, each rubbing roller may be configured to have its own driving system, or the second rubbing that rotates counterclockwise. Only the rubbing roller 27 may have a unique drive system, and the first rubbing roller 25 that rotates on the trail may be driven by the photosensitive drum 14.

  Further, the pressure contact force of the first rubbing roller 25 and the second rubbing roller 27 to the photosensitive drum 14 may be the same or different. Here, if the pressure contact force of the second rubbing roller 27 on the downstream side with respect to the rotation direction of the photosensitive drum 14 is smaller than that of the first rubbing roller 25 on the upstream side, the second rubbing rotating counter is performed. The fluctuation of the rotation of the photosensitive drum 14 by the rubbing roller 27 can be suppressed, and the occurrence of image unevenness (jitter) can be suppressed.

  FIG. 4 is an enlarged view showing another configuration example of the image forming unit 9. In FIG. 4, a charging roller 15a for charging the photosensitive drum 14 by applying an AC voltage or an AC voltage component in contact with the photosensitive drum 14 and a charging cleaning roller 15b for cleaning the charging roller 15a. A device 15 is provided. In addition, as the first rubbing roller 25 of the cleaning device 17, a roller having an outer diameter larger than that of the second rubbing roller 27 is used. The structure of other parts is the same as that shown in FIG.

  When the charging device 15 including the charging roller 15a is used, if a large amount of toner passes through the cleaning blade 29, the toner external additive adheres to the surface of the charging roller 15a, and the resistance of the portion of the charging roller 15a to which the external additive has adhered is reduced. There is a possibility that the surface potential of the photosensitive drum 14 may decrease and increase. However, in the configuration of the present embodiment, the second rubbing roller 27 that counter-rotates with respect to the photosensitive drum 14 peels off the residual toner on the photosensitive drum 14, so that the contamination of the charging roller 15 a can be reduced. Further, since the cleaning burden on the charging cleaning roller 15b is reduced, the life of the charging cleaning roller 15b is also extended.

  Further, since the outer diameter of the first rubbing roller 25 on the upstream side with respect to the rotation direction of the photoconductor drum 14 is larger than that of the second rubbing roller 27, the nip portion with the photoconductor drum 14 (photoconductor in the circumferential direction). The first rubbing roller 25 is wider than the second rubbing roller 27 with respect to the width of the portion substantially in contact with the drum 14. Therefore, the residual toner on the photosensitive drum 14 is likely to adhere to the first rubbing roller 25, and more toner can adhere to the second rubbing roller 27, so that the polishing effect and the cleaning effect are enhanced. Can do.

  Further, since the outer diameters of the first rubbing roller 25 and the second rubbing roller 27 are different, the first rubbing roller 25 is always in contact with the second rubbing roller 27 at a different portion every time it rotates. become. Therefore, the toner can be uniformly attached to the second rubbing roller 27, and the polishing force of the second rubbing roller 27 can be sufficiently exerted.

  In addition, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the meaning of this invention. For example, the materials, shapes, relative arrangements, and the like of the component parts described in the above embodiments are not intended to limit the scope of the present invention, but merely illustrative examples, unless otherwise specified. . In FIG. 4, the charging roller 15 a is configured to contact the surface of the photosensitive drum 14 to charge the surface of the photosensitive drum 14, but the charging roller 15 a does not cover the surface of the photosensitive drum 14. There are other embodiments configured to charge in contact. Also in this embodiment, substantially the same effect can be obtained by substantially the same action as described above. The photosensitive drum 14 of the above embodiment has an a-Si-based inorganic photosensitive layer, but is composed of an inorganic photosensitive layer made of another inorganic material (for example, Se-based inorganic material) or an organic material. Even in a configuration having an organic photosensitive layer (OPC), the effect of the present invention can be obtained.

  In the above embodiment, the first rubbing roller 25 and the second rubbing roller 27 in which an elastic layer is formed around the core metal are used, and abrasive particles are provided between the photosensitive drum 14 and the rubbing rollers 25 and 27. However, the present invention is not limited to this, and a rubbing roller having another configuration may be used. For example, a rubbing roller containing abrasive particles on the surface of the elastic layer is pressed against the surface of the photosensitive drum 1 and rubbed, or a rubbing roller is used as a magnet roller, and a magnetic carrier and toner formed on the roller surface are used. A conventionally known rubbing roller, such as a structure in which the surface of the photosensitive drum 14 is rubbed by using a magnetic brush of the cleaning agent or a structure in which a fur brush-like rubbing roller is pressed against the surface of the photosensitive drum 14 and rubbed. Is mentioned.

  Further, the present invention is not limited to the monochrome laser printer shown in FIG. 1, but an analog monochrome copying machine, a rotary or tandem color copying machine, a color printer, a copying machine such as an analog monochrome copying machine, a facsimile, etc. Of course, the present invention can be applied to various image forming apparatuses.

  A tandem type color printer having the cleaning device 17 of the present invention shown in FIG. 2 mounted in each image forming unit was manufactured. The cleaning device 17 uses a first rubbing roller 25 and a second rubbing roller 27 made of EPDM having a diameter of 15.5 mm, and the peripheral speed ratio of the first rubbing roller 25 to the photosensitive drum is 1 (trailing). Rotation), the peripheral speed ratio of the second rubbing roller 27 was set to 0.8 (counter rotation). The pressure contact force against the photosensitive drum was 13N. A cleaning blade 29 made of urethane rubber is arranged downstream of the second rubbing roller 27 with respect to the rotation direction of the photosensitive drum 14.

  As another configuration of the color printer, an a-Si photosensitive drum having an outer diameter of 40 mm was used, and the drum peripheral speed was set to 340 mm / sec. As the charging device, a scorotron charger using a gold-plated tungsten wire having a diameter of 60 μm was used, and a toner mixed with 0.1% to 0.5% of titanium oxide as an abrasive was used.

  Instead of the scorotron charger, a tandem type color printer having a charging roller made of epichlorohydrin rubber rotating following the photosensitive drum was manufactured. Other configurations including the cleaning device 17 are the same as those in the first embodiment.

  A tandem color printer in which the peripheral speed ratio of the first rubbing roller 25 and the second rubbing roller 27 to the photosensitive drum was 1 was manufactured. Other configurations including the cleaning device 17 were the same as those in Example 2.

  A tandem color printer was manufactured in which the peripheral speed ratio of the first rubbing roller 25 and the second rubbing roller 27 to the photosensitive drum was 1.2. Other configurations including the cleaning device 17 were the same as those in Example 2.

  A tandem color printer in which the diameter of the second rubbing roller 27 was 12 mm was manufactured. Other configurations including the cleaning device 17 were the same as those in Example 2.

A tandem type color printer in which the pressure of the second rubbing roller 27 against the photosensitive drum was 10 N was manufactured. Other configurations including the cleaning device 17 were the same as those in Example 2.
(Test example)

  The polishing effect on the surface of the photosensitive drum in the image forming apparatus equipped with the cleaning device of the present invention was evaluated. The evaluation method is the same as in Example 1 except that the color printer of the present invention manufactured in Examples 1 to 6 and the first rubbing roller 25 and the second rubbing roller are arranged in a non-contact state. Using the color printer of Comparative Example 1 having the configuration, 1,000 test images (printing rate 1.5%) were continuously printed in a low temperature and high humidity environment (15 ° C., humidity 50%), and the friction coefficient of the drum surface. Was measured. The presence or absence of image flow and jitter was evaluated visually. Further, in Examples 2 to 6, adhesion of the toner external additive to the charging roller was also observed. The results are shown in Table 1.

  As apparent from Table 1, in the color printers of Examples 1 to 6, no image flow occurred. Also, the friction coefficient of the drum surface was as low as 0.30 to 0.40. In addition, in the color printers of Examples 2 to 6 including the charging roller, adhesion of the toner external additive to the charging roller was also suppressed. On the other hand, in Comparative Example 1 in which the first rubbing roller 25 and the second rubbing roller 27 were not brought into contact with each other, the toner did not adhere sufficiently to the second rubbing roller 27, so the polishing effect was low and the friction coefficient on the drum surface was high. Occurrence of image flow was also observed. Further, since the amount of toner interposed between the second rubbing roller 27 and the photosensitive drum is small, the frictional resistance of the second rubbing roller 27 is increased and jitter is generated. Note that the friction coefficient of Example 1 is lower than others when the scorotron charger is used, and the discharge product is less likely to adhere to the surface of the photosensitive drum than when the charging roller is used. This is because the friction coefficient is low before rubbing.

  In comparison between Example 2 and Examples 3 and 4, the friction coefficients were smaller in the order of Examples 4, 3 and 2. The reason for this is that in Example 3, the peripheral speed ratio of the second rubbing roller to the photosensitive drum is larger than in Example 2, and in Example 4, the first rubbing roller 25 and the second rubbing roller against the photoconductor drum. Since the peripheral speed ratio of 27 is larger than that of Example 2, it is considered that the polishing effect becomes higher in the order of Examples 2, 3, and 4.

  In the fifth embodiment in which the outer diameter of the second rubbing roller 27 is smaller than that of the first rubbing roller 25, the toner adheres more uniformly to the second rubbing roller 27 than in the second embodiment. Became smaller. Further, it was confirmed that the occurrence of jitter was further suppressed in Example 6 in which the pressing force of the second rubbing roller 27 was small.

  INDUSTRIAL APPLICABILITY The present invention can be used in a cleaning apparatus having a mechanism for polishing the surface of an image carrier using a rubbing roller, and the residual toner on the image carrier is attached to the surface to polish the surface of the image carrier 2. The first rubbing roller located on the upstream side in the moving direction of the image carrier is in order with respect to the moving direction of the image carrier. The second rubbing roller that rotates and is located on the downstream side in the moving direction of the image carrier rotates reversely with respect to the moving direction of the image carrier.

  As a result, the toner can be reliably attached to the first rubbing roller and the second rubbing roller without using a separate member such as a scraper, and has a simple structure and excellent polishing effect on the surface of the image carrier. Can be provided. Further, if the rotation speeds of the first and second rubbing rollers are made equal, the wear of the first and second rubbing rollers can be suppressed and the life can be extended, and the rotation speed of the first rubbing roller can be increased. When the speed is different from the moving speed of the image carrier, the polishing effect of the cleaning device can be improved by generating a polishing effect on the first rubbing roller.

  Further, if the outer diameter of the first rubbing roller is made larger than that of the second rubbing roller, the residual toner on the image carrier is likely to adhere to the first rubbing roller, and more toner is transferred to the second rubbing roller. Can be attached to a roller. Further, since the rotating first rubbing roller and the second rubbing roller are always in contact with each other at different portions, the toner can be uniformly attached to the second rubbing roller. Furthermore, if the pressing force of the second rubbing roller against the image carrier is made smaller than that of the first rubbing roller, the occurrence of jitter due to the shake of the image carrier can be suppressed.

  Further, when the cleaning blade is provided on the downstream side of the second rubbing roller with respect to the moving direction of the image carrier, the toner passing through the cleaning blade is reduced, the cleaning load of the cleaning blade is reduced, and the cleaning performance is improved. In addition, it is possible to prevent dielectric breakdown of the image carrier due to frictional charging of the toner staying at the cleaning blade or at the edge and causing discharge.

  And, by mounting the cleaning device of the present invention, it is possible to suppress the adhesion of discharge products to the image carrier, so that it is possible to effectively suppress the increase in the surface friction coefficient of the image carrier and the occurrence of image flow. Image forming apparatus.

FIG. 2 is a schematic cross-sectional view showing the configuration of an image forming apparatus equipped with the cleaning device of the present invention. FIG. 2 is an enlarged view of an image forming unit in FIG. 1. These are the elements on larger scale around the 1st rubbing roller and the 2nd rubbing roller in a cleaning device. FIG. 5 is an enlarged view showing another configuration example of the image forming unit.

Explanation of symbols

9 Image forming unit 14 Photosensitive drum (image carrier)
15 Charging device 15a Charging roller (charging member)
DESCRIPTION OF SYMBOLS 16 Developing apparatus 17 Cleaning apparatus 18 Transfer roller 19 Laser scanning unit 25 1st rubbing roller 27 2nd rubbing roller 29 Cleaning blade 30 Conveying spiral 100 Image forming apparatus

Claims (8)

Having two rubbing rollers that are pressed against the surface of the image carrier at a predetermined pressure, and that adheres residual toner on the image carrier to the surface to polish the surface of the image carrier;
The rubbing rollers are arranged in contact with each other, and the first rubbing roller located upstream in the moving direction of the image carrier rotates forward with respect to the moving direction of the image carrier, A cleaning device, wherein the second rubbing roller located downstream in the moving direction rotates in the reverse direction with respect to the moving direction of the image carrier.   The cleaning device according to claim 1, wherein the rotation speeds of the first and second rubbing rollers are equal.   The cleaning device according to claim 1, wherein a rotation speed of the first rubbing roller is different from a moving speed of the image carrier.   The cleaning device according to claim 1, wherein an outer diameter of the first rubbing roller is larger than that of the second rubbing roller.   5. The cleaning device according to claim 1, wherein a pressure contact force of the second rubbing roller with respect to the image carrier is smaller than that of the first rubbing roller.   6. The cleaning blade according to claim 1, further comprising a cleaning blade pressed against the surface of the image carrier at a predetermined pressure on a downstream side of the second rubbing roller in the moving direction of the image carrier. The cleaning apparatus in any one.   An image forming apparatus comprising the cleaning device according to claim 1.   8. The image forming apparatus according to claim 7, further comprising a charging member that charges the surface of the image carrier in a contact or non-contact state downstream of the cleaning device in the moving direction of the image carrier. .

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