JP2008158230A - Cleaning device and image forming apparatus incorporating it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cleaning device capable of maintaining appropriate cleaning performance by ensuring removal of discharge products from the surface of an image carrier while suppressing a significant cost increase. <P>SOLUTION: The cleaning device 80 includes: a cleaning roller 82 and cleaning blade 83 for cleaning off sticking matter on the surface of photoreceptor drum 21; and a toner receiving member 84 disposed with a gap left from the surface of the cleaning roller 82 and used for storing toner, removed from the photoreceptor drum 21, between the cleaning roller 82 and the member 84. The cross-section of the cleaning roller 82, with a right angle to its axial line, has an elliptical shape in which distances from the axial center to the periphery differ according to circumferential directions. The cleaning roller 82 repeats the cycle of contact with the toner receiving member 84 and separation therefrom as it rotates. This motion makes it possible to forcibly increase pressure for attaching toner to the surface of the cleaning roller automatically according to the rotation of the cleaning roller. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a cleaning device for transferring a toner image onto a sheet and then removing adhering matter such as toner remaining on the surface of an image carrier to perform cleaning. The present invention also relates to an electrophotographic image forming apparatus typified by a copying machine or a printer equipped with this cleaning device.

  In an electrophotographic image forming apparatus such as a copying machine or a printer, a photosensitive drum is widely used as an image carrier. A general image forming operation using the photosensitive drum is as follows. The surface of the photosensitive drum is uniformly charged with a predetermined potential by a charging device, and by irradiating the LED light or the like of the exposure device there, the potential is partially attenuated to form an electrostatic latent image of an original image. Is done. The electrostatic latent image is developed with a developing device, whereby a toner image is formed on the surface of the photosensitive drum. This toner image is transferred to the sheet when the sheet is inserted into a transfer region formed by bringing the photosensitive drum and the transfer member into contact with each other or close to each other.

  In such an image forming apparatus, after a toner image is transferred to a sheet, a small amount of toner may remain on the surface of the photosensitive drum without being transferred to the sheet. The residual toner adhering to the surface of the photosensitive drum becomes an obstacle to the next new image formation, so that it needs to be cleaned. As a cleaning method used for such a purpose, a method of moving and collecting residual toner on the rotating member by pressing a cleaning roller, a rotating brush, or the like that is a rotating member on the surface of the photosensitive drum, or a surface of the photosensitive drum A method of scraping residual toner by bringing a cleaning blade into contact therewith, or a cleaning method combining these methods is widely known.

  On the other hand, when an amorphous silicon photoconductor is used as the photoconductor, it is known that discharge products easily adhere to the surface of the photoconductor due to the discharge of the charging device. When this discharge product absorbs moisture, the electrical resistance on the surface of the photoreceptor is lowered, and a problem of image flow that disturbs the electrostatic latent image may occur. For this reason, a small amount of abrasive is mixed in the toner, and the cleaning roller and the cleaning blade are used in combination to remove the residual toner adhering to the surface of the photosensitive member, and a small amount of toner is carried on the surface of the cleaning roller. There is known a method of cleaning by discharging the discharge product adhering to the surface of the photoreceptor.

Examples of the cleaning method for removing the discharge products attached to the surface of the photosensitive drum using the cleaning roller and the cleaning blade as described above can be found in Patent Documents 1 to 4.
Japanese Patent Laid-Open No. 11-3012 (page 2-3, FIG. 1-2) JP 2003-156970 A (page 3, FIG. 1-2) Japanese Patent Laying-Open No. 2005-62492 (page 5-6, FIG. 1) Japanese Patent Laying-Open No. 2005-49540 (page 4, FIG. 1)

  The image forming apparatus described in Patent Document 1 is a flat surface of a housing that receives toner removed from the surface of the photosensitive drum, below a cleaning roller (polishing roller) that contacts the photosensitive drum and polishes the surface thereof. Is inclined so that the cleaning roller (polishing roller) side is lower than the toner collecting screw side to make it easier to store toner around the cleaning roller, and a toner regulating member is brought into contact with the cleaning roller from below. Yes. However, in such an image forming apparatus, since the toner regulating member is always in contact with the cleaning roller, the cleaning roller may be easily worn. As a result, the life of the cleaning roller is shortened, and the toner carrying force on the surface of the cleaning roller may be reduced. Further, between the cleaning roller and the toner regulating member, the toner concentrates only at a linear (strip-shaped) portion extending in the axial direction of the cleaning roller where they are in contact with each other, so that the effect of attaching the toner to the surface of the cleaning roller is low. .

  The image forming apparatuses described in Patent Document 2 and Patent Document 3 try to adhere toner (abrasive particles) to the surface of the cleaning roller by using electrostatic force. However, in such an image forming apparatus, the abrasive particles used for polishing the surface of the cleaning roller and contained in the toner are composed of a metal oxide such as titanium oxide or alumina. Hard to adhere to the roller surface.

  For the above reasons, it becomes difficult to carry an appropriate amount of toner on the surface of the cleaning roller. As a result, the surface of the photosensitive drum is not sufficiently polished by the cleaning roller, and there is a high possibility that the discharge product attached to the surface of the photosensitive member cannot be removed.

  On the other hand, in the image forming apparatus described in Patent Document 4, a heater is disposed inside the photosensitive drum, and the photosensitive drum is heated from the inside to prevent generation of moisture absorbed by the discharge product. However, in this image forming apparatus, the cost for installing the heater is greatly increased. This also leads to an increase in running cost of the image forming apparatus. In addition to these cost increases, it is necessary to consider the effect of temperature rise inside the image forming apparatus due to the use of heaters. Considering adverse effects on peripheral components and safety against heating. The problem of having to do also occurs.

  Here, as a consideration for environmental destruction such as prevention of global warming in recent years, in an image forming apparatus, in a charging device for charging an image carrier, a charging method is changed from a corona wire charging method that easily generates ozone to a roller charging method. Is changing. Although the roller charging method generates less ozone than the corona wire charging method, the discharge rate of the discharge product to the surface of the photoconductor is very fast because the discharge to the photoconductor is performed in a very small space. . Accordingly, it is necessary to maintain the cleaning performance of the image carrier surface by the cleaning roller at a high level. Therefore, if an appropriate amount of toner is not reliably carried on the surface of the cleaning roller, there is a higher possibility that the discharge product attached to the surface of the photoreceptor cannot be removed, and there is a problem that image flow is likely to occur.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and in a cleaning device that removes deposits such as toner remaining on the surface of an image carrier after cleaning the toner image onto a sheet, the cost is greatly increased. An appropriate amount of toner can be reliably supported on the surface of the cleaning roller that removes deposits adhering to the surface of the image carrier with a toner containing an abrasive, and is suitable for the surface of the image carrier. An object of the present invention is to provide a cleaning device capable of maintaining a good cleaning performance. Another object of the present invention is to provide a high-performance image forming apparatus equipped with such a cleaning device.

  In order to solve the above-mentioned problems, the present invention is provided with a cleaning roller that removes deposits on the surface of the image carrier while rotating in contact with the image carrier, and is provided downstream of the cleaning roller in the image carrier rotation direction. A cleaning device including a cleaning blade that contacts the carrier and scrapes off toner on the surface thereof, and includes a toner receiving member that stores toner removed from the image carrier between the cleaning roller, and the cleaning roller includes: The cross-sectional shape perpendicular to the axis is a shape in which the distance from the center of the axis to the outer peripheral surface differs depending on the position in the circumferential direction, and the contact and separation with the toner receiving member are periodically repeated with rotation. did.

  In the cleaning device having the above-described configuration, the cleaning roller has an elliptical cross-sectional shape perpendicular to its axis.

  In the cleaning device having the above-described configuration, the cleaning roller has a cross-sectional shape perpendicular to the axis of the cleaning roller such that an intermediate portion of each side of the polygon bulges outward.

  Further, in the cleaning device having the above-described configuration, the toner receiving member is a bowl-shaped member along a curved surface drawn by a track of the outer peripheral portion farthest from the axis center of the cleaning roller.

  In the cleaning device having the above-described configuration, the friction coefficient of the toner receiving member with the toner on the surface thereof is smaller than the friction coefficient with the toner on the surface of the cleaning roller.

  In the cleaning device having the above-described configuration, the cleaning blade is disposed on the lower side in the vertical direction with respect to the cleaning roller.

  In the present invention, the cleaning device is mounted on the image forming apparatus.

  In the image forming apparatus having the above configuration, the surface of the image carrier is charged by a charging roller.

  According to the configuration of the present invention, the cleaning roller that rotates in contact with the image carrier and removes deposits on the surface thereof is provided on the downstream side of the cleaning roller in the rotation direction of the image carrier, and contacts the image carrier. And a cleaning blade for scraping off the toner on the surface of the cleaning device, the cleaning device includes a toner receiving member for storing the toner removed from the image carrier between the cleaning roller and the cleaning roller at right angles to the axis thereof. The cross-sectional shape that forms the distance between the center of the axis and the outer peripheral surface varies depending on the position in the circumferential direction, and contact and separation with the toner receiving member are periodically repeated with rotation. Or the toner removed from the surface of the image carrier by the cleaning blade is stored in the toner receiving member. Thus, pressure can be applied from the periphery of the cleaning roller to adhere to the cleaning roller, and the pressure for adhering toner to the surface of the cleaning roller can be forcibly increased automatically as the cleaning roller rotates. . Thereby, it is possible to prevent the toner from being easily separated from the surface of the cleaning roller. Accordingly, it is possible to form a suitable toner layer on the surface of the cleaning roller while suppressing a significant cost increase, and to effectively polish the surface of the image carrier using the toner containing the abrasive by the cleaning roller. be able to. As a result, the discharge product adhering to the surface of the image carrier can be surely removed, and a cleaning device capable of maintaining a suitable cleaning performance for the surface of the image carrier can be obtained.

  Further, since the cleaning roller has an elliptical cross-sectional shape perpendicular to the axis thereof, the cleaning roller makes contact with the toner receiving member at the major axis of the ellipse every time the cleaning roller rotates halfway. It is possible to repeat the separation at the position of the short axis. Then, in the process where the elliptical long axis portion of the cleaning roller moves along the surface of the toner receiving member, the pressure for gradually attaching the toner to the surface of the cleaning roller can be increased. Accordingly, it is possible to obtain a configuration in which the toner can be easily carried on the surface of the cleaning roller without hindering the smooth flow of the toner in the vicinity of the surface of the cleaning roller. Therefore, it is possible to further improve the cleaning performance for the surface of the image carrier without aggregating the toner in the toner storage space of the toner receiving member.

  In addition, since the cleaning roller has a cross-sectional shape perpendicular to the axis thereof, the intermediate portion of each side of the polygon swells outward, so that each time the cleaning roller makes one rotation, the toner receiving member It is possible to repeat the contact and separation with a plurality of times. Thereby, the toner can be applied to many places on the surface of the cleaning roller by applying pressure from the surroundings. Therefore, it is possible to easily obtain a configuration in which toner is more easily carried on the surface of the cleaning roller.

  Further, since the toner receiving member is a bowl-shaped member along the curved surface drawn by the track of the outer peripheral portion farthest from the center of the axis of the cleaning roller, the space for storing the toner is further reduced, and the cleaning roller The toner removed from the surface of the image carrier can be applied to the surface of the cleaning roller by applying pressure from the periphery of the toner. Therefore, it is possible to improve the cleaning performance for the surface of the image carrier. Furthermore, the space occupied by the toner receiving member can be reduced, and the cleaning device can be made compact.

  Further, since the friction coefficient of the toner receiving member with the toner on the surface thereof is smaller than the friction coefficient with the toner on the surface of the cleaning roller, the toner is more likely to adhere to the cleaning roller surface than the toner receiving member surface. can do. Therefore, the toner can be efficiently carried on the surface of the cleaning roller, and a toner layer suitable for polishing the surface of the image carrier can be formed on the surface of the cleaning roller.

  Further, since the cleaning blade is disposed on the lower side in the vertical direction with respect to the cleaning roller, the toner removed from the surface of the image carrier falls immediately below without adhering to the cleaning roller. This can be prevented by providing a toner receiving member. Therefore, even when the cleaning roller is provided in the upper part of the housing of the cleaning device and the cleaning blade is provided below the cleaning roller, the surface of the image carrier is polished by the cleaning roller by the action of the toner receiving member. The discharge product adhering to the surface of the image carrier can be surely removed.

  In the present invention, since the cleaning device is mounted on the image forming apparatus, an appropriate amount of toner can be reliably supported on the surface of the cleaning roller while suppressing a significant increase in cost. On the other hand, a high-performance image forming apparatus capable of maintaining a suitable cleaning performance can be obtained.

  In addition, charging the surface of the image bearing member with a charging roller has less ozone generation than the corona wire charging method, so it is designed with consideration for environmental destruction such as prevention of global warming. I can say that. However, on the other hand, there is a problem that the discharge rate of the discharge product on the surface of the photoconductor is very fast due to the small discharge space with respect to the photoconductor, but when combined with the image forming apparatus of the present invention, Provided is an image forming apparatus capable of exhibiting a high level of cleaning performance on the surface of an image carrier by using a cleaning roller having an appropriate amount of toner carried on the surface, so that a higher quality image can be obtained without causing image flow. It is possible.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  First, the image output operation of the image forming apparatus equipped with the cleaning device according to the first embodiment of the present invention will be described while explaining the outline of the structure with reference to FIG. FIG. 1 is a schematic vertical sectional front view of an image forming apparatus. This image forming apparatus is of a color printing type in which a toner image is transferred onto a sheet using an intermediate transfer belt.

  As shown in FIG. 1, a paper feed cassette 3 is disposed below the inside of the main body 2 of the image forming apparatus 1. The paper feed cassette 3 stores and accommodates paper P such as cut paper before printing. The sheets P are separated and sent one by one toward the upper left of the sheet cassette 3 in FIG. The paper feed cassette 3 can be pulled out horizontally from the front side of the main body 2.

  A first paper transport unit 4 is provided inside the main body 2 and to the left of the paper feed cassette 3. The first paper transport unit 4 is formed substantially vertically along the left side surface of the main body 2. The first paper transport unit 4 receives the paper P sent out from the paper feed cassette 3 and transports the paper P vertically upward along the left side surface of the main body 2 to the secondary transfer unit 40.

  A manual paper feed unit 5 is provided above the paper feed cassette 3 at a location on the right side which is the side opposite to the left side of the main body 2 where the first paper transport unit 4 is formed. Yes. In the manual sheet feeder 5, paper P of a size that is not contained in the paper cassette 3, thick paper, and OHP sheets that are to be fed one by one are placed.

  A second paper transport unit 6 is provided on the left side of the manual paper feed unit 5. The second paper transport unit 6 is located immediately above the paper feed cassette 3, extends substantially horizontally from the manual paper feed unit 5 to the first paper transport unit 4, and joins the first paper transport unit 4. Then, the second paper transport unit 6 receives the paper P or the like sent from the manual paper feed unit 5 and transports it to the first paper transport unit 4 substantially horizontally.

  On the other hand, the image forming apparatus 1 receives document image data from an external computer (not shown). The information of the image data is sent to a laser irradiation unit 7 that is an exposure unit disposed above the second paper transport unit 6. The laser irradiation unit 7 irradiates the image forming unit 20 with laser light L controlled based on the image data.

  A total of four image forming units 20 are provided above the laser irradiation unit 7, and an intermediate transfer belt 8 using an intermediate transfer member in the form of an endless belt is provided above each image forming unit 20. The intermediate transfer belt 8 is supported by being wound around a plurality of rollers, and is rotated clockwise in FIG. 1 by a driving mechanism (not shown).

  As shown in FIG. 1, the four image forming units 20 are of a so-called tandem system that are arranged in a line from the upstream side to the downstream side in the rotational direction along the rotational direction of the intermediate transfer belt 8. The four image forming units 20 are, in order from the upstream side, a magenta image forming unit 20M, a cyan image forming unit 20C, a yellow image forming unit 20Y, and a black image forming unit 20B. These image forming units 20 are replenished with a developer (toner) by a developer supply container and a conveying unit (not shown) corresponding to each color. In the following description, the identification symbols “M”, “C”, “Y”, and “B” are omitted unless particularly limited.

  In each image forming unit 20, an electrostatic latent image of a document image is formed by the laser light L irradiated by the laser irradiation unit 7 serving as an exposure unit, and the toner image is developed from the electrostatic latent image. The toner image is primarily transferred onto the surface of the intermediate transfer belt 8 by a primary transfer unit 30 provided above each image forming unit 20. As the intermediate transfer belt 8 rotates, the toner image of each image forming unit 20 is transferred to the intermediate transfer belt 8 at a predetermined timing. A color toner image is formed by superimposing the color toner images.

  A secondary transfer unit 40 including a secondary transfer roller 41 is disposed at a position where the intermediate transfer belt 8 is suspended on the sheet conveyance path. The color toner image on the surface of the intermediate transfer belt 8 is a secondary formed by the intermediate transfer belt 8 and the secondary transfer roller 41 being pressed against the paper P sent in synchronization by the first paper transport unit 4. Transferred at the transfer nip.

  After the secondary transfer, deposits such as toner remaining on the surface of the intermediate transfer belt 8 are cleaned for the intermediate transfer belt 8 provided upstream of the intermediate transfer belt 8 in the rotation direction of the magenta image forming unit 20M. It is cleaned and collected by the device 9.

  A fixing unit 10 is provided above the secondary transfer unit 40. The paper P carrying the unfixed toner image in the secondary transfer unit 40 is sent to the fixing unit 10 where the toner image is heated and pressed by the heat roller and the pressure roller to be fixed.

  A branch portion 11 is provided above the fixing portion 10. The sheet P discharged from the fixing unit 10 is discharged from the branching unit 11 to the sheet discharging unit 12 provided on the upper part of the image forming apparatus 1 when double-sided printing is not performed.

  The discharge port portion from which the paper P is discharged from the branch portion 11 toward the paper discharge portion 12 functions as the switchback portion 13. When performing duplex printing, the switchback unit 13 switches the transport direction of the paper P discharged from the fixing unit 10. Then, the sheet P is sent downward through the branching unit 11, the left side of the fixing unit 10, and the left side of the secondary transfer unit 40, and again passes through the first sheet transport unit 4 to the secondary transfer unit 40. Sent.

  Next, a detailed configuration around the image forming unit 20 of the image forming apparatus 1 will be described with reference to FIGS. 2 is a vertical sectional view showing the periphery of the image forming portion, FIG. 3 is a vertical sectional view showing the periphery of the cleaning device, and FIG. 4 is a partially enlarged perspective view of a toner receiving member of the cleaning device. Since the four color image forming units 20 have the same structure, the identification symbols “M”, “C”, “Y”, and “B” are omitted as described above.

  As shown in FIG. 2, the image forming unit 20 includes a photosensitive drum 21 as an image carrier at the center thereof. In the vicinity of the photosensitive drum 21, a charging device 50, a developing device 60, a charge removal device 70, and a drum cleaning device 80 are arranged in this order along the rotation direction. The primary transfer unit 30 is provided between the developing device 60 and the charge removal device 70 along the rotation direction of the photosensitive drum 21.

  The photosensitive drum 21 extends in the paper width direction perpendicular to the paper conveyance direction in the image forming apparatus 1, that is, the depth direction of the paper surface in FIG. The photosensitive drum 21 is an inorganic photosensitive drum in which an amorphous silicon photosensitive layer, which is an inorganic photoconductive material, is provided on the outside of a conductive roller-shaped substrate made of aluminum or the like by vacuum deposition or the like, and has a diameter of 30 mm. It is. The photosensitive drum 21 is rotated by a driving mechanism (not shown) so that the peripheral speed thereof is substantially the same as the paper transport speed (147 mm / s).

  As shown in FIG. 2, the charging device 50 includes a charging roller 52 in contact with the photosensitive drum 21 inside the housing 51. The charging roller 52 is in pressure contact with the photosensitive drum 21 with a predetermined pressure, and rotates according to the rotation of the photosensitive drum 21. By this charging roller 52, the surface of the photosensitive drum 21 is uniformly charged with a predetermined polarity and potential. The charging potential at this time is usually about 200 to 1000V. In the housing 51, a cleaning brush 53 is provided at a position separating the charging roller 52 from the photosensitive drum 21, and the surface of the charging roller 52 is cleaned by the cleaning brush 53.

  As shown in FIG. 2, the developing device 60 includes a developing roller 62 and a supply screw 63 inside the housing 61. The developing roller 62 is in contact or non-contact with the developing system, and is provided in the vicinity of the photosensitive drum 21. A bias having the same polarity as the charging polarity of the photosensitive drum 21 is applied to the developing roller 62. The developing roller 62 charges the toner, which is a developer, and moves it to the electrostatic latent image on the surface of the photosensitive drum 21 to develop the electrostatic latent image.

  The developing device 60 uses a two-component toner obtained by mixing a magnetic carrier and a non-magnetic toner as a developer, but may be of a type using a magnetic or non-magnetic one-component toner. Absent. Further, in order to clean the surface of the photosensitive drum 21 by polishing, a small amount of powder of titanium oxide, alumina or the like is mixed in the toner as an abrasive. The toner is accommodated in a toner supply container (not shown), conveyed to a location of the developing device 60 by a conveying means (not shown), and replenished inside the housing 61 by a supply screw 63.

  As shown in FIG. 2, the primary transfer unit 30 is provided with a primary transfer roller 31 that comes into contact with the photosensitive drum 21 via the intermediate transfer belt 8. The primary transfer roller 31 rotates according to the rotation of the intermediate transfer belt 8 by contacting the intermediate transfer belt 8 without having a driving mechanism. The primary transfer roller 31 is applied with a primary transfer bias of minus 500 to minus 1000 V, which has a polarity different from the charging polarity of the photosensitive drum 21 or toner, as necessary.

  As shown in FIG. 1, the intermediate transfer belt 8 is wound around and supported by a plurality of rollers. The intermediate transfer belt 8 is constituted by an elastic belt in which a rubber layer is laminated on the surface of a base layer made of a synthetic resin. As materials, polyvinylidene fluoride (PVDF) and chloroprene rubber (CR) are used for the base layer, silicon and urethane, and polytetrafluoroethylene (PTFE) and urethane are used for the coating.

  As shown in FIG. 2, the static eliminating device 70 is disposed on the downstream side of the primary transfer unit 30 along the rotation direction of the photosensitive drum 21. The static eliminator 70 includes an LED (light emitting diode) 71 and a reflector 72. The LED 71 is attached to the upper surface of the housing 81 of the cleaning device 80. Instead of the LED 71, an EL (electroluminescence) light source, a fluorescent lamp, or the like can be used. The reflector 72 is provided above the LED 71 so as to cover the LED 71. The neutralization device 70 irradiates the photosensitive drum 21 with the neutralization light of the LED 71, thereby removing the charged charge on the surface and preparing for the charging process in the next image forming operation.

  The cleaning device 80 is disposed further downstream of the primary transfer unit 30 and the charge removal device 70 along the rotation direction of the photosensitive drum 21. As shown in FIGS. 2 and 3, the cleaning device 80 includes a cleaning roller 82, a cleaning blade 83, a toner receiving member 84, a transport paddle 85, and a toner discharge screw 86 inside the housing 81.

  As shown in FIGS. 2 and 3, the cleaning roller 82 is disposed in the upper portion of the housing 81, and the cross-sectional shape perpendicular to the axis is different in distance from the center of the axis to the outer peripheral surface depending on the position in the circumferential direction. It has an elliptical shape. The cleaning roller 82 is made of a foamed ethylene propylene rubber having a hardness of 50 ° (conforming to JIS standard A) around a mandrel having a diameter of 8 mm and having a thickness of 1 mm at the minor axis of the ellipse and 3 mm at the major axis. The foamed EPDM is provided, and has substantially the same axial length as the photosensitive drum 21. The cleaning roller 82 is provided to be pressed against the photosensitive drum 21 with a maximum force of 1,000 gf by biasing means (not shown) provided at both ends of the shaft portion. The cleaning roller 82 contacts the photosensitive drum 21 around the elliptical long axis and is separated from the photosensitive drum 21 at the short axis.

  The cleaning roller 82 is rotated by a driving mechanism (not shown) constituted by a motor or the like. In order to efficiently polish the surface of the photosensitive drum 21, it is necessary to rotate the cleaning roller 82 at a predetermined peripheral speed. As a result, the cleaning roller 82 is rotated in such a direction that the surface at the contact point with the photosensitive drum 21 moves in the same direction as the surface of the photosensitive drum 21, and the peripheral speed of the cleaning roller 82 at the long axis of the ellipse is increased. The circumferential speed of the photosensitive drum 21 is set to 1.6 times. The cleaning roller 82 collects deposits such as residual toner from the surface of the photosensitive drum 21 and also cleans the surface of the photosensitive drum 21 with the toner containing the abrasive adhered to the surface of the cleaning roller 82. Fulfill.

  As shown in FIGS. 2 and 3, the cleaning blade 83 is disposed downstream of the cleaning roller 82 in the rotation direction of the photosensitive drum 21 and on the lower side in the vertical direction with respect to the cleaning roller 82 in the housing 81. Yes. The cleaning blade 83 is provided by being pressed against the photosensitive drum 21 by an urging means (not shown) so that the linear pressure at the contact portion is 48 N / m. The cleaning blade 83 is a rectangular parallelepiped member such as a 2.2 mm-thick plate extending in the drum axial direction and made of urethane rubber having a hardness of 77 ° (conforming to JIS standard A). 21 has substantially the same axial length. The cleaning blade 83 plays a role of cleaning so as to scrape off deposits such as toner remaining on the surface of the photosensitive drum 21.

  As shown in FIGS. 2 and 3, the toner receiving member 84 is disposed immediately below the cleaning roller 82 and between the cleaning roller 82 and the toner discharge screw 86. The toner receiving member 84 is configured by curving a thin plate-like member made of stainless steel (SUS) as shown in FIG. Further, the surface of the toner receiving member 84 is coated with a fluororesin so that the friction coefficient between the surface and the toner is smaller than the friction coefficient between the surface of the cleaning roller 82 and the toner.

  The toner receiving member 84 extends in the circumferential direction of the cleaning roller 82 so as to be away from the contact point between the photosensitive drum 21 and the cleaning roller 82, that is, from the vicinity of the cleaning blade 83 toward the downstream side in the rotation direction of the cleaning roller 82. The cleaning roller 82 has a hook shape extending along a curved surface (a two-dot chain line in FIG. 3) drawn by the outermost track of the cleaning roller 82 from the center of the axis, and has almost the same length as the cleaning roller 82 in the axial direction. is doing.

  Further, as shown in FIG. 3, the toner receiving member 84 contacts the surface of the cleaning roller 82 around the elliptical long axis portion of the cleaning roller 82 and is separated around the short axis portion. The contact pressure at the contact portion between the cleaning roller 82 and the toner receiving member 84 is about 300 gf. This is not because they are in firm contact with each other, but the toner that moves from the surface of the photosensitive drum 21 along the peripheral surface of the cleaning roller 82 due to the pressure in the toner storage space of the toner receiving member 84 is in contact with this. The pressure is such that it does not interfere with passage through the location.

  The toner receiving member 84 divides the space in which the cleaning roller 82 and the cleaning blade 83 are disposed from the space in which the toner discharge screw 86 is provided in the housing 81, leaving the upper portion of the toner receiving member 84. Thus, a configuration is obtained in which the toner removed from the surface of the photosensitive drum 21 can be easily stored in a space near the peripheral surface of the cleaning roller 82. However, many small holes (not shown) are provided so that the pressure of the toner entering the gap between the toner receiving member 84 and the cleaning blade 83 becomes too high and the cleaning blade 83 is not excessively pressed against the photosensitive drum 21. It is provided. If the toner pressure becomes too high, the toner moves to the toner discharge screw 86 side through this hole.

  As illustrated in FIG. 2, the transport paddle 85 is disposed below the upper end portion of the toner receiving member 84 and in the vicinity of the inner wall of the housing 81. The transport paddle 85 has substantially the same axial length as the cleaning roller 82 and is rotated by a drive mechanism (not shown). The transport paddle 85 serves to prevent toner overflowing from the upper portion of the toner receiving member 84 from staying in the vicinity of the inner wall of the housing 81 and transport the toner toward the toner discharge screw 86.

  The toner discharge screw 86 is provided below the cleaning roller 82 in the housing 81. The toner discharge screw 86 is a rotating member that rotates about an axis substantially parallel to the axis of the photosensitive drum 21 or the cleaning roller 82, and collects waste toner provided from the inside of the housing 81 to the outside of the image forming unit 20. It extends to a container (not shown). The toner discharge screw 86 is removed from the surface of the photosensitive drum 21 and serves to discharge waste toner or the like in the housing 81 used for cleaning to the outside of the housing 81, that is, to a waste toner collection container.

  The cleaning device 80 as described above uses the cleaning roller 82 and the cleaning blade 83 after the toner image on the surface of the photosensitive drum 21 is transferred to the intermediate transfer belt 8, and the toner remaining on the surface of the photosensitive drum 21. Remove deposits and clean.

  Next, the cleaning operation of the surface of the photosensitive drum 21 by the cleaning device 80 according to the present invention will be described with reference to FIGS. 5 to 13 in addition to FIG.

  First, prior to describing the cleaning performance provided by the cleaning device 80 for removing deposits such as discharge products deposited on the surface of the photosensitive drum 21, the relationship between the surface state of the photosensitive drum 21 and the occurrence of image flow. Will be described with reference to FIGS.

  FIG. 5 is a graph showing the influence of the dynamic friction coefficient of the surface of the photosensitive drum on the electric resistance value of the surface. FIG. 6 is a graph showing the influence of the toner recovery amount of the cleaning device on the dynamic friction coefficient of the surface of the photosensitive drum. FIG. 6 is a graph showing the influence of the toner amount on the surface of the cleaning roller on the coefficient of dynamic friction on the surface of the photosensitive drum.

  It has been found that the image flow generated on the surface of the photosensitive drum 21 is likely to occur when the electric resistance value on the surface is less than about 1.2E + 11 [Ω]. In FIG. 5, the electric resistance value on the surface of the photosensitive drum 21 is indicated by a two-dot chain line. Therefore, in order to prevent the occurrence of image flow, the electric resistance value on the surface of the photosensitive drum 21 needs to be about 1.2E + 11 [Ω] or more. From FIG. It turns out that it is necessary to hold below 0.5.

In order to prevent the occurrence of image flow, in order to keep the dynamic friction coefficient on the surface of the photosensitive drum 21 at 0.5 or less, the toner recovery amount of the cleaning device 80 is about 25 mg per printing paper as shown in FIG. It must be done so. Further, regarding the toner amount on the surface of the cleaning roller 82, it is necessary to carry a toner amount of 7 mg / cm ² from FIG.

  Subsequently, the actual cleaning operation of the surface of the photosensitive drum 21 with respect to the toner amount to be carried on the surface of the cleaning roller 82 necessary for preventing the occurrence of the image flow on the surface of the photosensitive drum 21 as described above. In addition to FIG. 3, it demonstrates using FIGS. 8-13.

  FIG. 8 is a vertical sectional view showing the periphery of the cleaning device similar to FIG. 3, and shows a state in which the cleaning roller starts to contact the toner receiving member. FIG. 9 is a vertical cross section showing the periphery of the cleaning device similar to FIG. FIG. 10 shows a state in which the rotation of the cleaning roller is further advanced than in FIG. 8, and FIG. 10 is a vertical sectional view showing the periphery of the cleaning device similar to FIG. 9, and the rotation of the cleaning roller has further advanced from FIG. FIG. 11 is a vertical sectional view showing the periphery of the cleaning device similar to FIG. 10 and shows the state where the rotation of the cleaning roller has further advanced from FIG. 10, and FIG. 12 shows the sectional shape of the cleaning roller is photosensitive. FIG. 13 is a graph showing the influence on the dynamic friction coefficient of the surface of the photosensitive drum. FIG. 13 shows the effect of the surface state of the toner receiving member on the dynamic friction coefficient of the surface of the photosensitive drum. Influence is a graph showing.

  In FIG. 8, the toner removed from the surface of the photosensitive drum 21 by the cleaning roller 82 and the cleaning blade 83 tends to move below the cleaning roller 82 and the cleaning blade 83 due to the action of gravity. However, this toner movement is blocked by the toner receiving member 84, and the toner is stored in a space formed between the toner receiving member 84 and the cleaning roller 82.

  As described above, the cleaning roller 82 and the toner receiving member 84 are in contact with each other at the position of the elliptical long axis of the cleaning roller 82 (see FIG. 8). As a result, the toner is pressed against the cleaning roller 82 and adheres to the surface of the cleaning roller 82 from below. Toner is stored between the cleaning roller 82 and the toner receiving member 84 at a location downstream of the cleaning roller 82 in the rotation direction, and the toner pressure is also increased at this location.

  When the rotation of the cleaning roller 82 proceeds as shown in FIG. 9, the cleaning roller 82 rotates so as to rub the inner surface of the toner receiving member 84, and the toner at the contact point and the downstream side in the rotation direction. The pressure in the storage space is increased. In the upper part of the toner receiving member 84, the toner overflows and spills out so as to be pushed out by the cleaning roller 82.

  When the cleaning roller 82 further rotates as shown in FIG. 10, the contact portion of the cleaning roller 82 with the toner receiving member 84 reaches the upper end portion of the toner receiving member 84, and the surface of the cleaning roller 82 of toner Compulsory adhesion to is completed. On the other hand, the cleaning roller 82 comes into contact with the surface of the photosensitive drum 21 at the position of the long axis opposite to the cleaning roller 82. Here, the cleaning roller 82 polishes the surface of the photosensitive drum 21 with toner containing an abrasive attached to the surface. The toner removed from the surface of the photosensitive drum 21 by the cleaning roller 82 and the cleaning blade 83 is stored on the toner receiving member 84 below the cleaning roller 82.

  As the cleaning roller 82 further rotates, the major axis portion of the cleaning roller 82 away from the upper end of the toner receiving member 84 is positioned upward in a state where toner is carried as shown in FIG. Then, the portion of the long axis on the opposite side is rotated and pressed against the toner receiving member 84 to increase the pressure in the toner storage space, and the toner gradually adheres to the surface of the cleaning roller 82.

  In this way, the cleaning roller 82 repeats contact and separation with the toner receiving member 84 as it rotates, thereby enhancing the adhesion of the toner to the surface. While the cleaning roller 82 rotates, the toner overflowing at the upper portion of the toner receiving member 84 spills downward along the inner wall of the housing 81 and reaches the location of the toner discharge screw 86 via the transport paddle 85. The toner reaching the toner discharge screw 86 is conveyed to the outside of the housing 81 by the toner discharge screw 86.

  FIG. 12 shows the cleaning performance of the surface of the photosensitive drum 21 brought about by the operation of the cleaning device 80 as described above. According to FIG. 12, when the cross-sectional shape of the cleaning roller 82 is circular, the coefficient of dynamic friction on the surface of the photosensitive drum 21 is settled at about 0.7 over time. On the other hand, when the sectional shape of the cleaning roller 82 is elliptical as in the above configuration, the dynamic friction coefficient on the surface of the photosensitive drum 21 is settled at about 0.4. Accordingly, the cross-sectional shape of the cleaning roller 82 is not a circle but an ellipse, so that the coefficient of dynamic friction on the surface of the photosensitive drum 21 is a necessary condition for preventing the occurrence of image flow on the surface of the photosensitive drum 21. It is below 5.

  FIG. 13 shows the influence of the surface state of the toner receiving member 84 on the cleaning performance of the surface of the photosensitive drum 21. According to FIG. 13, when the surface of the toner receiving member 84 remains stainless steel that has not been subjected to any treatment, the dynamic friction coefficient of the surface of the photosensitive drum 21 gradually increases with time, and the printing time is 900 [s]. It becomes about 0.65. On the other hand, when the surface of the toner receiving member 84 is coated with a fluororesin, the dynamic friction coefficient of the surface of the photosensitive drum 21 settles to about 0.4 at an early stage. Therefore, it is a necessary condition for preventing the occurrence of image flow on the surface of the photosensitive drum 21 by making the friction coefficient with the toner on the surface of the toner receiving member 84 smaller than the friction coefficient with the toner on the surface of the cleaning roller 82. The coefficient of dynamic friction of the surface of the photosensitive drum 21 can be less than 0.5. The verification according to FIG. 13 was performed with the cleaning roller 82 having a circular cross-sectional shape. However, when the cross-sectional shape is an elliptical shape, the same or higher effect can be expected.

  Next, a detailed configuration of the cleaning device according to the second embodiment of the present invention will be described with reference to FIG. FIG. 14 is a vertical cross section showing the periphery of the cleaning roller of the cleaning device. Since the basic configuration of this embodiment is the same as that of the first embodiment described with reference to FIGS. 1 to 4, the configuration common to the first embodiment is described in the drawings, and The description will be omitted.

  In the cleaning device 80 according to the second embodiment, the cleaning roller 87 has a substantially triangular shape in which the cross-sectional shape perpendicular to the axis is a shape in which the distance from the axis center to the outer peripheral surface varies depending on the position in the circumferential direction. There is no. Regarding this cross-sectional shape, each side of the triangle has a shape in which an intermediate portion swells outward. As the cleaning roller 87 rotates, the cleaning roller 87 comes into contact with the surface of the photosensitive drum 21 only at the apex of the triangle and is separated at other locations. That is, the cleaning roller 87 contacts the surface of the photosensitive drum 21 three times for each rotation. The effect regarding the cleaning performance provided by the cleaning roller 87 will be described in detail later together with the first embodiment and other embodiments that follow.

  Next, a detailed configuration of the cleaning device according to the third embodiment of the present invention will be described with reference to FIG. FIG. 15 is a vertical section showing the periphery of the cleaning roller of the cleaning device. Since the basic configuration of this embodiment is the same as that of the first embodiment described with reference to FIGS. 1 to 4, the configuration common to the first embodiment is described in the drawings, and The description will be omitted.

  In the cleaning device 80 according to the third embodiment, the cleaning roller 88 has a substantially rectangular shape in which the cross-sectional shape perpendicular to the axis is a shape in which the distance from the axis center to the outer peripheral surface varies depending on the position in the circumferential direction. There is no. Regarding this cross-sectional shape, each side of the quadrilateral has a shape in which an intermediate portion swells outward. As the cleaning roller 88 rotates, the cleaning roller 88 comes into contact with the surface of the photosensitive drum 21 only at the apex of the quadrangle and is separated at other locations. That is, the cleaning roller 88 contacts the surface of the photosensitive drum 21 four times for each rotation. The effect of the cleaning roller 88 regarding the cleaning performance will be described in detail later together with the first and second embodiments and other embodiments that follow.

  Next, the detailed configuration of the cleaning device according to the fourth embodiment of the present invention will be described with reference to FIG. FIG. 16 is a vertical cross section showing the periphery of the cleaning roller of the cleaning device. Since the basic configuration of this embodiment is the same as that of the first embodiment described with reference to FIGS. 1 to 4, the configuration common to the first embodiment is described in the drawings, and The description will be omitted.

  In the cleaning device 80 according to the fourth embodiment, the cleaning roller 89 has a hexagonal shape in which the cross-sectional shape perpendicular to the axis is a shape in which the distance from the axis center to the outer peripheral surface varies depending on the position in the circumferential direction. ing. As the cleaning roller 89 rotates, the cleaning roller 89 contacts the surface of the photosensitive drum 21 only at the apex of the hexagon, and is separated at other locations. That is, the cleaning roller 89 comes into contact with the surface of the photosensitive drum 21 six times for each rotation. The effect of the cleaning roller 89 regarding the cleaning performance will be described in detail later together with the first to third embodiments and the next fifth embodiment.

  Next, a detailed configuration of the cleaning device according to the fifth embodiment of the present invention will be described with reference to FIG. FIG. 17 is a vertical cross section showing the periphery of the cleaning roller of the cleaning device. Since the basic configuration of this embodiment is the same as that of the first embodiment described with reference to FIGS. 1 to 4, the configuration common to the first embodiment is described in the drawings, and The description will be omitted.

  In the cleaning device 80 according to the fifth embodiment, the cleaning roller 90 has an octagonal shape in which the cross-sectional shape perpendicular to the axis is a shape in which the distance from the axis center to the outer peripheral surface varies depending on the position in the circumferential direction. ing. As the cleaning roller 90 rotates, the cleaning roller 90 comes into contact with the surface of the photosensitive drum 21 only at the apex of the octagon and is separated at other locations. That is, the cleaning roller 90 comes into contact with the surface of the photosensitive drum 21 eight times every rotation. The effect of the cleaning roller 90 on the cleaning performance will be described in detail together with the first to fourth embodiments.

  The cleaning performance of the surface of the photosensitive drum 21 provided by the cleaning roller according to the first to fifth embodiments will be described with reference to FIG. FIG. 18 is a table showing the influence of each cross-sectional shape of the cleaning roller on the dynamic friction coefficient of the surface of the photosensitive drum.

  In FIG. 18, circular data as a comparative example and data of polygonal examples other than the first to fifth embodiments are also shown. Further, in FIG. 18, “expansion” of each shape means that an intermediate portion of each side of the polygon is expanded outward.

  As shown in FIG. 18, the elliptical shape is the most effective for the sectional shape of the cleaning roller, and the dynamic friction coefficient on the surface of the photosensitive drum 21 is 0.4. In addition, triangular expansion, triangular expansion, and quadrilateral expansion are less than the dynamic friction coefficient 0.5 of the surface of the photosensitive drum 21, which is a necessary condition for preventing the occurrence of image flow on the surface of the photosensitive drum 21. The quadrilateral and the polygon with more sides are the result that the dynamic friction coefficient of the surface of the photosensitive drum 21 exceeds 0.5. Further, it can be seen that, as an effect when the middle portion of each side of the polygon is expanded outward, in the triangle or quadrilateral, the expansion is effective when the coefficient of dynamic friction on the surface of the photosensitive drum 21 is lowered.

  As described above, the cleaning roller that contacts and rotates on the photosensitive drum 21 and removes deposits on the surface thereof is provided on the downstream side of the rotational direction of the photosensitive drum 21 with respect to the cleaning drum. The cleaning device 80 includes a cleaning blade 83 that contacts and scrapes the toner on the surface thereof, and includes a toner receiving member 84 that stores the toner removed from the photosensitive drum 21 between the cleaning roller and the cleaning roller. The cross-sectional shape perpendicular to the axis is a shape in which the distance from the center of the axis to the outer peripheral surface differs depending on the position in the circumferential direction, and the contact and separation with the toner receiving member 84 are periodically repeated with rotation. , Removed from the surface of the photosensitive drum 21 by a cleaning roller or a cleaning blade 83. By storing the toner in the toner receiving member 84, pressure can be applied from the periphery of the cleaning roller to adhere to the cleaning roller, and toner is automatically attached to the surface of the cleaning roller as the cleaning roller rotates. Pressure can be increased forcibly. Thereby, it is possible to prevent the toner from being easily separated from the surface of the cleaning roller. Accordingly, a suitable toner layer can be formed on the surface of the cleaning roller while suppressing a significant cost increase, and the surface of the photosensitive drum 21 using the toner containing the abrasive by the cleaning roller is effectively polished. can do. As a result, it is possible to surely remove the discharge product adhering to the surface of the photosensitive drum 21 and obtain the cleaning device 80 capable of maintaining a suitable cleaning performance for the surface of the photosensitive drum 21. it can.

  Further, since the cleaning roller 82 has an elliptical cross-sectional shape perpendicular to the axis thereof, the cleaning roller 82 contacts the toner receiving member 84 at the position of the major axis of the ellipse every time the cleaning roller 82 rotates halfway. It is possible to repeat the separation at the position of the shaft. Then, in the process in which the elliptical long axis portion of the cleaning roller 82 moves along the surface of the toner receiving member 84, the pressure for gradually attaching the toner to the surface of the cleaning roller 82 can be increased. Thus, it is possible to obtain a configuration in which the toner can be easily carried on the surface of the cleaning roller 82 without hindering the smooth flow of toner near the surface of the cleaning roller 82. Therefore, it is possible to further improve the cleaning performance for the surface of the photosensitive drum 21 without aggregating the toner in the toner storage space of the toner receiving member 84.

  Further, since the cleaning rollers 87 and 88 have a cross-sectional shape perpendicular to the axis thereof, the intermediate portion of each side of the polygon swells outward, so that each time the cleaning rollers 87 and 88 make one rotation, The contact and separation with the receiving member 84 can be repeated a plurality of times. As a result, the toner can be applied to many places on the surfaces of the cleaning rollers 87 and 88 by applying pressure from the surroundings. Therefore, it is possible to easily obtain a configuration in which toner is more easily carried on the surfaces of the cleaning rollers 87 and 88.

  Further, since the toner receiving member 84 is a bowl-shaped member along the curved surface drawn by the track of the outer peripheral portion farthest from the center of the axis of the cleaning roller, the space for storing the toner is further reduced, and from the periphery of the cleaning roller By applying pressure, the toner removed from the surface of the photosensitive drum 21 can adhere to the surface of the cleaning roller. Therefore, the cleaning performance for the surface of the photosensitive drum 21 can be improved. Furthermore, the space occupied by the toner receiving member 84 can be reduced, and the cleaning device 80 can be made compact.

  Further, since the friction coefficient of the toner receiving member 84 with the toner on the surface thereof is smaller than the friction coefficient with the toner on the surface of the cleaning roller, the toner is more easily attached to the cleaning roller surface than the surface of the toner receiving member 84. Can do. Therefore, the toner can be efficiently carried on the surface of the cleaning roller, and a toner layer suitable for polishing the surface of the photosensitive drum 21 can be formed on the surface of the cleaning roller.

  Since the cleaning blade 83 is disposed on the lower side in the vertical direction with respect to the cleaning roller, the toner removed from the surface of the photosensitive drum 21 does not adhere to the cleaning roller and falls immediately below. This can be prevented by providing the toner receiving member 84. Therefore, even if the cleaning roller 80 is provided in the upper portion of the housing 81 of the cleaning device 80 and the cleaning blade 83 is provided below the cleaning roller, the photosensitive member by the cleaning roller is operated by the toner receiving member 84. Polishing of the surface of the drum 21 can be performed effectively, and the discharge product adhering to the surface of the photosensitive drum 21 can be surely removed.

  In the present invention, since the cleaning device 80 is mounted on the image forming apparatus 1, an appropriate amount of toner can be surely carried on the surface of the cleaning roller while suppressing a significant cost increase, and the surface of the photosensitive drum 21 can be surely supported. In contrast, a high-performance image forming apparatus 1 capable of maintaining a suitable cleaning performance can be obtained.

  In addition, charging the surface of the photosensitive drum 21 with the charging roller 52 is less in the amount of ozone generated than the corona wire charging method, so it is designed with consideration for environmental destruction such as prevention of global warming. It can be said that there is. However, on the other hand, there is a problem that the discharge rate of the discharge product on the surface of the photoconductor is very fast due to the small discharge space with respect to the photoconductor, but it is combined with the image forming apparatus 1 of the present invention. Since a high level of cleaning performance for the surface of the photosensitive drum 21 can be exhibited using a cleaning roller having an appropriate amount of toner supported on the surface, an image forming apparatus 1 that does not generate image flow and can obtain a higher quality image. Can be provided.

  Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the invention.

  For example, the embodiment of the present invention has a structure in which the cleaning blade 83 is disposed on the lower side in the vertical direction with respect to the cleaning roller, but may have a structure in which the cleaning blade 83 is disposed on the upper side in the vertical direction with respect to the cleaning roller. Absent. Even in such a structure, the toner receiving member 84 for storing the toner removed from the photosensitive drum 21 between the cleaning roller and the cleaning roller is provided, and the cleaning roller has a cross-sectional shape perpendicular to the axis thereof in the circumferential direction. According to the position, the distance from the center of the axis to the outer peripheral surface is different, and the contact and separation with the toner receiving member 84 are repeated with rotation, so that the same operation and effect as in this embodiment can be obtained. Can do.

  Further, in the first to fifth embodiments of the present invention, the cross-sectional shape of the cleaning roller is an elliptical shape, a triangle, a quadrangle, a hexagon, and an octagon with the middle portion of each side bulging outward. The cross-sectional shape is not limited to this, and other shapes as shown in FIG. 18 may be used as long as the distance from the center of the axis to the outer peripheral surface varies depending on the position in the circumferential direction. . The cross-sectional shape of the cleaning roller does not need to be a regular polygon, and whether or not the middle portion of each side is expanded outward is arbitrary.

  Further, the image forming apparatus 1 is of a color printing type in which the toner image is transferred onto the paper P using the intermediate transfer belt 8, but the type of the image forming apparatus is not limited to this, and the intermediate transfer belt is not limited thereto. It may be a model that does not use, or a model for monochrome printing.

  The present invention can be used in general cleaning apparatuses that transfer a toner image onto a sheet and then remove the adhering matter such as toner remaining on the surface of the image carrier to perform cleaning.

1 is a schematic vertical sectional front view of an image forming apparatus equipped with a cleaning device according to a first embodiment of the present invention. FIG. 2 is a vertical sectional view showing the periphery of an image forming unit of the image forming apparatus of FIG. 1. FIG. 3 is a vertical sectional view showing the periphery of a cleaning device of the image forming unit in FIG. 2. FIG. 4 is a partially enlarged perspective view of a toner receiving member of the cleaning device shown in FIG. 3. It is a graph which shows the influence which the dynamic friction coefficient of the surface of a photoreceptor drum has on the electrical resistance value of the surface. 6 is a graph showing the influence of the toner recovery amount of the cleaning device on the dynamic friction coefficient of the surface of the photosensitive drum. 6 is a graph showing the influence of the toner amount on the surface of the cleaning roller on the coefficient of dynamic friction on the surface of the photosensitive drum. FIG. 4 is a vertical sectional view showing the periphery of the cleaning device similar to FIG. 3, and shows a state in which the cleaning roller starts to contact the toner receiving member. FIG. 9 is a vertical sectional view showing the periphery of the cleaning device similar to FIG. 8 and shows a state in which the rotation of the cleaning roller has further advanced from FIG. 8. FIG. 10 is a vertical sectional view showing the periphery of the cleaning device similar to FIG. 9 and shows a state where the rotation of the cleaning roller has further advanced from FIG. 9. FIG. 11 is a vertical sectional view showing the periphery of the cleaning device similar to FIG. 10 and shows a state where the rotation of the cleaning roller has further advanced from FIG. 10. 6 is a graph showing the influence of the cross-sectional shape of the cleaning roller on the dynamic friction coefficient of the surface of the photosensitive drum. 6 is a graph showing the influence of the surface state of the toner receiving member on the dynamic friction coefficient of the surface of the photosensitive drum. It is a vertical sectional view showing the periphery of the cleaning roller of the cleaning device according to the second embodiment of the present invention. It is a vertical sectional view showing the periphery of the cleaning roller of the cleaning device according to the third embodiment of the present invention. It is a vertical sectional view showing the periphery of a cleaning roller of a cleaning device according to a fourth embodiment of the present invention. It is a vertical sectional view showing the periphery of a cleaning roller of a cleaning device according to a fifth embodiment of the present invention. 6 is a table showing the effect of each cross-sectional shape of the cleaning roller on the dynamic friction coefficient of the surface of the photosensitive drum.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 8 Intermediate transfer belt 20 Image forming part 21 Photosensitive drum (image carrier)
DESCRIPTION OF SYMBOLS 30 Primary transfer part 50 Charging apparatus 52 Charging roller 60 Developing apparatus 70 Static elimination apparatus 80 Cleaning apparatus 81 Housing 82, 87-90 Cleaning roller 83 Cleaning blade 84 Toner receiving member 85 Conveying paddle 86 Toner discharge screw

Claims (8)

A cleaning roller that rotates in contact with the image carrier and removes deposits on the surface thereof, and is provided downstream of the cleaning roller in the image carrier rotation direction, and contacts the image carrier and scrapes the toner on the surface. In a cleaning device comprising a cleaning blade to take
A toner receiving member that stores toner removed from the image carrier between the cleaning roller and the cleaning roller has a cross-sectional shape that is perpendicular to the axis of the cleaning roller. The cleaning apparatus is characterized in that the distance between the two is different and the contact and separation with the toner receiving member are periodically repeated with rotation.   The cleaning device according to claim 1, wherein the cleaning roller has an elliptical cross-sectional shape perpendicular to an axis thereof.   The cleaning device according to claim 1, wherein the cleaning roller has a cross-sectional shape perpendicular to an axis of the cleaning roller such that a middle portion of each side of the polygon bulges outward.   4. The toner receiving member according to any one of claims 1 to 3, wherein the toner receiving member is a bowl-shaped member along a curved surface drawn by a track of an outer peripheral portion furthest away from the axis center of the cleaning roller. The cleaning device described.   The cleaning device according to claim 1, wherein the toner receiving member has a friction coefficient with the toner on the surface thereof that is smaller than a friction coefficient with the toner on the surface of the cleaning roller. .   The cleaning device according to claim 1, wherein the cleaning blade is disposed on the lower side in the vertical direction with respect to the cleaning roller.   An image forming apparatus comprising the cleaning device according to claim 1.   The image forming apparatus according to claim 7, wherein the surface of the image carrier is charged by a charging roller.

Images