JP4953798B2 - Cleaning device and image forming apparatus equipped with the same - Google Patents

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 adhering 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. In a cleaning device comprising a cleaning blade that contacts the carrier and scrapes off the toner on the surface, the toner is disposed with a gap with respect to the surface of the cleaning roller, and the toner removed from the image carrier is removed from the cleaning roller. A toner receiving member that is stored in between, and a moving mechanism that moves at least one of the cleaning roller and the toner receiving member toward the other in a direction in which the gap is narrowed to contact the cleaning roller and the toner receiving member. It was decided.

  In the cleaning device having the above-described configuration, the toner receiving member is a bowl-shaped member along the peripheral surface of the cleaning roller.

  Further, in the cleaning device having the above-described configuration, the cleaning roller and the toner receiving member may be arranged on the tip of the toner receiving member that extends in the circumferential direction of the cleaning roller so as to be away from the contact portion between the image carrier and the cleaning roller. Contact was made at the end side.

  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 that scrapes off the toner on the surface of the cleaning roller. The toner is disposed with a gap with respect to the surface of the cleaning roller, and stores the toner removed from the image carrier between the cleaning roller and the cleaning roller. Since there is provided a receiving member and a moving mechanism for moving at least one of the cleaning roller and the toner receiving member toward the other in a direction in which the gap is narrowed, and bringing the cleaning roller and the toner receiving member into contact with each other. Toner removed from the image carrier surface by the cleaning roller or cleaning blade -By storing in the receiving member, pressure can be applied from the periphery of the cleaning roller to adhere to the cleaning roller, and if necessary, the pressure to adhere toner to the surface of the cleaning roller can be forcibly increased. Can do. 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.

  In addition, since the toner receiving member is a bowl-shaped member along the peripheral surface of the cleaning roller, the space for storing the toner is further reduced, and pressure is applied from the periphery of the cleaning roller to apply the surface of the image carrier. The toner removed from the toner can be adhered to the surface of the cleaning roller. 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.

  The cleaning roller and the toner receiving member are in contact with each other at a position on the end side of the toner receiving member that extends in the circumferential direction of the cleaning roller so as to be away from the contact position between the image carrier and the cleaning roller. Therefore, the toner removed from the surface of the image carrier at the contact portion between the image carrier and the cleaning roller moves along the peripheral surface of the cleaning roller toward the contact portion between the cleaning roller and the toner receiving member. In this process, the pressure in the toner storage space can be gradually 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.

  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 in which a high-level cleaning performance with respect to the surface of an image carrier can be exhibited using a cleaning roller having a proper 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, an image output operation of an image forming apparatus equipped with a cleaning device according to an embodiment of the present invention will be described 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 to the surface of the intermediate transfer belt 8 by the 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, so that the surface of the intermediate transfer belt 8 is magenta, cyan, yellow, or black. 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 outer side 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 partition member 85, a transport paddle 86, and a toner discharge screw 87 inside a housing 81. A moving mechanism 90 for the toner receiving member 84 is provided outside the housing 81.

  As shown in FIGS. 2 and 3, the cleaning roller 82 is provided at the upper part in the housing 81, and biasing means (not shown) provided at both ends of the shaft portion has one cleaning roller 82 per side with respect to the photosensitive drum 21. , 000 gf of force is provided. The cleaning roller 82 is configured by providing a foamed ethylene propylene rubber (foamed EPDM) having a thickness of 2 mm and a hardness of 50 ° (compliant with JIS standard A) around a core metal having a diameter of 10 mm. Have approximately the same axial length.

  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 is one of that of the photosensitive drum 21. .2x is set. 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 87. 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. It has a bowl shape extending along the peripheral surface of the cleaning roller 82 and has a length substantially the same as the axial length of the cleaning roller 82.

  Further, as shown in FIGS. 3 and 4, the toner receiving member 84 has a shaft portion extending in the axial direction of the cleaning roller 82 from a central portion extending in the circumferential direction of the cleaning roller 82 to a lower portion of the portion on the photosensitive drum 21 side. 84a. The toner receiving member 84 is rotatably supported by the housing 81 by a shaft portion 84a at both ends of the cleaning roller 82 in the axial direction.

  As shown in FIG. 3 and FIG. 4, a moving mechanism 90 is provided at locations on both ends of the toner receiving member 84 in the axial direction of the cleaning roller 82. The moving mechanism 90 of the toner receiving member 84 is provided outside the housing 81 as described above, and includes a support piece 91, a solenoid 92, and a tension spring 93.

  The support piece 91 is disposed at the end of the shaft portion 84 a of the toner receiving member 84 that protrudes outside the housing 81. The support piece 91 has a flat plate shape and is provided so as to protrude in the direction away from the photosensitive drum 21 from the axial center of the shaft portion 84a outward in the radial direction. As shown in FIG. 4, the engaging portion 91a is engaged with the solenoid 92 on the lower surface of the support piece 91, and the engaging portion 91b is engaged with the tension spring 93 on the upper surface. Is provided.

  As shown in FIG. 3, the solenoid 92 is disposed below the support piece 91 and includes an electromagnet 92a and a movable iron core 92b. In the solenoid 92, a movable iron core 92b is inserted into an electromagnet 92a configured in a cylindrical shape, and the axis of the movable iron core 92b is arranged along the vertical direction. In the solenoid 92, the electromagnet 92a is supported by the housing 81, and the tip of the movable iron core 92b is connected to the engaging portion 91a (see FIG. 4) on the lower surface of the support piece 91.

  As shown in FIG. 3, the tension spring 93 is disposed on the upper side of the support piece 91 so as to face the solenoid 92 disposed on the lower side. The tension spring 93 is disposed along the axis of the movable iron core 92b of the solenoid 92, one end is supported by the housing 81, and the other end is coupled to the engaging portion 91b (see FIG. 4) on the upper surface of the support piece 91. Yes.

  Such a moving mechanism 90 of the toner receiving member 84 is such that the movable iron core 92b of the solenoid 92 is attracted to the electromagnet 92a when the power is on and moves downward, and the upper side is activated by the action of the tension spring 93 when the power is off. To do. As a result, the support piece 91 rotates about the axis of the shaft portion 84a of the toner receiving member 84, so that the toner receiving member 84 itself also rotates about the axis of the shaft portion 84a.

  A partition member 85 is provided below the toner receiving member 84. The partition member 85 has a flat plate shape and is provided between the cleaning blade 83 and the toner discharge screw 87 so as to extend between the inner walls of the housing 81 at both ends in the axial direction of the cleaning roller 82. The partition member 85 extends from the inner bottom surface of the housing 81 to a position reaching the lower surface of the toner receiving member 84 in the vertical direction.

  The partition member 85 and the toner receiving member 84 are provided with a space in the housing 81 where the cleaning roller 82 and the cleaning blade 83 are disposed, and a toner discharge screw 87, leaving the upper portion of the toner receiving member 84. The configuration is such that the toner removed from the surface of the photosensitive drum 21 is easily stored in the 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 partition member 85 and the cleaning blade 83 becomes too high and the cleaning blade 83 is not excessively pressed against the photosensitive drum 21. It is. If the toner pressure becomes too high, the toner moves to the toner discharge screw 87 side through this hole.

  As shown in FIG. 2, the transport paddle 86 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 conveyance paddle 86 has substantially the same axial length as the cleaning roller 82, and is rotated by a driving mechanism (not shown). The transport paddle 86 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 87.

  The toner discharge screw 87 is provided below the cleaning roller 82 in the housing 81. The toner discharge screw 87 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 outside the image forming unit 20 from the inside of the housing 81. It extends to a container (not shown). The toner discharge screw 87 serves to discharge waste toner or the like in the housing 81 that is removed from the surface of the photosensitive drum 21 and 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 will be described with reference to FIGS. 5 to 11 in addition to FIG.

  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. Is a graph showing the effect of the toner amount on the surface of the cleaning roller on the coefficient of dynamic friction on the surface of the photosensitive drum, and FIG. 8 is a vertical sectional view showing the periphery of the cleaning device similar to FIG. 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 toner receiving member is in contact with the cleaning roller. FIG. 10 is a diagram showing the position of the toner receiving member on the surface of the photosensitive drum. FIG. 11 is a graph showing the influence of the surface condition of the toner receiving member on the dynamic friction coefficient of the surface of the photosensitive drum. It is.

  Prior to the description of the cleaning performance for removing deposits such as discharge products deposited on the surface of the photosensitive drum 21 provided by the above-described embodiment of the present invention, first, the surface state of the photosensitive drum 21 and the image flow are determined. The relationship with occurrence will be described with reference to FIGS.

  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. 8-11.

  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, the movement of the toner is blocked by the toner receiving member 84 and stored in a space near the peripheral surface of the cleaning roller 82 constituted by the toner receiving member 84. When the toner is stored in this space, pressure is applied to the cleaning roller 82 and adheres to the surface of the cleaning roller 82 from below.

  The toner receiving member 84 is held at the normal position shown in FIG. 8 by the moving mechanism 90 shown in FIG. At this time, the solenoid 92 of the moving mechanism 90 is in a power-on state, and the movable iron core 92b is attracted to the electromagnet 92a and moves downward against the elastic force of the tension spring 93.

  Then, the cleaning roller 82 polishes the surface of the photosensitive drum 21 with toner containing an abrasive attached to the surface.

  During this time, the toner overflowing from the space near the peripheral surface of the cleaning roller 82 at the upper portion of the toner receiving member 84 spills downward along the inner wall of the housing 81, and the toner discharge screw 87 is located via the transport paddle 86. To reach. The toner that has reached the location of the toner discharge screw 87 is conveyed to the outside of the housing 81 by the toner discharge screw 87.

  Here, the amount of toner stored in the toner receiving member 84 is constantly monitored by using a detection device and a control device (not shown) of the toner occupation ratio and the transfer efficiency (toner recovery amount of the cleaning device) on the surface of the printing paper. Is made by As a result, when it is determined that the amount of toner to be carried on the surface of the cleaning roller 82 is small enough to perform suitable cleaning of the surface of the photosensitive drum 21, the toner receiving member 84 is moved by the moving mechanism 90 to the cleaning roller 82. Move towards.

  At this time, the solenoid 92 of the moving mechanism 90 shown in FIG. 3 is turned off, and the movable iron core 92 b moves upward by the action of the tension spring 93. As shown in FIG. 9, the toner receiving member 84 has a cleaning roller 82 at a position on the other end side extending in the circumferential direction of the cleaning roller 82 so as to be away from a contact position between the photosensitive drum 21 and the cleaning roller 82. Contact the surface. Note that the contact pressure between the cleaning roller 82 and the toner receiving member 84 is about 300 gf, and they are not firmly in contact with each other. The pressure is such that the toner moving along the peripheral surface of the cleaning roller 82 from the surface of the photosensitive drum 21 does not prevent the toner from passing through the contact portion.

  FIG. 10 shows the cleaning performance of the surface of the photosensitive drum 21 brought about by the operation of the cleaning device 80 described above. According to FIG. 10, when the toner receiving member 84 is fixed at the normal position shown in FIG. 8, the dynamic friction coefficient on the surface of the photosensitive drum 21 is settled at about 0.7 with time. On the other hand, when the position of the toner receiving member 84 is made variable as shown in FIG. 9, the dynamic friction coefficient on the surface of the photosensitive drum 21 is settled at about 0.4. Therefore, by moving the position of the toner receiving member 84, the dynamic friction coefficient 0.5 on 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, can be reduced. ing.

  FIG. 11 shows the influence of the surface condition of the toner receiving member 84 on the cleaning performance of the surface of the photosensitive drum 21. According to FIG. 11, 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.

  As described above, the cleaning roller 82 that removes deposits on the surface of the photosensitive drum 21 while rotating in contact with the photosensitive drum 21 and the downstream side of the cleaning roller 82 in the rotational direction of the photosensitive drum 21 are provided. In the cleaning device 80 provided with a cleaning blade 83 that contacts the surface 21 and scrapes off the toner on the surface, the cleaning roller 80 is disposed with a gap with respect to the surface of the cleaning roller 82 and removes the toner removed from the photosensitive drum 21. 82, and a moving mechanism 90 that moves the toner receiving member 84 toward the cleaning roller 82 in a direction in which the gap is narrowed to bring the cleaning roller 82 and the toner receiving member 84 into contact with each other. Cleaning roller 82 or cleaning block The toner removed from the surface of the photosensitive drum 21 by the roller 83 is stored in the toner receiving member 84, so that pressure can be applied from the periphery of the cleaning roller 82 to adhere to the cleaning roller 82, and further, if necessary. In addition, the pressure for adhering the toner to the surface of the cleaning roller 82 can be forcibly increased. Thereby, it is possible to prevent the toner from being easily separated from the surface of the cleaning roller 82. Therefore, it is possible to form a suitable toner layer on the surface of the cleaning roller 82 while suppressing a significant increase in cost, and it is effective to polish the surface of the photosensitive drum 21 using the toner containing the abrasive by the cleaning roller 82. Can be accomplished. 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 toner receiving member 84 is a bowl-shaped member along the peripheral surface of the cleaning roller 82, the space for storing the toner is further reduced, and pressure is applied from the periphery of the cleaning roller 82 to apply the surface of the photosensitive drum 21. The toner removed from the toner can adhere to the surface of the cleaning roller 82. 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, the cleaning roller 82 and the toner receiving member 84 are the end portions of the toner receiving member 84 that extend in the circumferential direction of the cleaning roller 82 so as to be away from the contact portion between the photosensitive drum 21 and the cleaning roller 82. Therefore, the toner removed from the surface of the photosensitive drum 21 at the contact portion between the photosensitive drum 21 and the cleaning roller 82 moves toward the contact portion between the cleaning roller 82 and the toner receiving member 84. In the process of moving along the peripheral surface, the pressure in the toner storage space can be gradually increased. Thereby, 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 the toner in the vicinity of 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 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 82, the toner is more easily attached to the surface of the cleaning roller 82 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 82, and a toner layer suitable for polishing the surface of the photosensitive drum 21 can be formed on the surface of the cleaning roller 82.

  Since the cleaning blade 83 is disposed on the lower side in the vertical direction with respect to the cleaning roller 82, the toner removed from the surface of the photosensitive drum 21 falls immediately without adhering to the cleaning roller 82. This can be prevented by providing the toner receiving member 84. Therefore, even if the cleaning roller 82 is provided in the upper part of the housing 81 of the cleaning device 80 and the cleaning blade 83 is provided below the cleaning roller 82, the cleaning roller 82 is operated by the action of the toner receiving member 84. Thus, the surface of the photosensitive drum 21 can be effectively polished, and the discharge product adhering to the surface of the photosensitive drum 21 can be reliably 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 reliably carried on the surface of the cleaning roller 82 while suppressing a significant cost increase, and the surface of the photosensitive drum 21. In contrast, it is possible to obtain a high-performance image forming apparatus 1 capable of maintaining a suitable cleaning performance.

  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 cleaning performance for the surface of the photosensitive drum 21 can be exhibited by using the cleaning roller 82 having an appropriate amount of toner carried on the surface, an image forming apparatus capable of obtaining a higher quality image with no image flow. 1 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 82, but is disposed on the upper side in the vertical direction with respect to the cleaning roller 82. It doesn't matter. Even in such a structure, there is provided a toner receiving member 84 that is disposed with a gap with respect to the surface of the cleaning roller 82 and stores the toner removed from the photosensitive drum 21 between the cleaning roller 82 and By providing the moving mechanism 90 for moving the toner receiving member 84 toward the cleaning roller 82 and bringing it into contact, the same operation and effect as in the present embodiment can be obtained.

  In the embodiment of the present invention, the toner receiving member 84 is moved toward and brought into contact with the cleaning roller 82. Conversely, the cleaning roller 82 is moved toward and brought into contact with the toner receiving member 84. It does not matter.

  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 an 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. 5 is a vertical sectional view showing the periphery of the cleaning device similar to FIG. 3, showing a state where the toner receiving member is in a normal position. FIG. 9 is a vertical sectional view showing the periphery of the cleaning device similar to FIG. 8, showing a state where the toner receiving member is in contact with the cleaning roller. 6 is a graph showing the influence of the position of the toner receiving member 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.

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 Cleaning roller 83 Cleaning blade 84 Toner receiving member 84a Shaft part 85 Partition member 86 Conveying paddle 87 Toner discharge screw 90 Moving mechanism

Claims (7)

And a cleaning roller for removing deposits on the surface thereof while rotating in contact with the image bearing member, provided on the image bearing member rotation direction downstream side of the cleaning roller, the toner on the surface thereof in contact with said image bearing member A cleaning device comprising a cleaning blade for scraping
Wherein the cleaning roller surface facing receiving toner becomes a state in contact with the state with the surface of the cleaning roller that will be arranged with a gap member, the other side at least one of the cleaning roller and the toner receiving member cleaning apparatus characterized by comprising a moving mechanism which moves into contact or away from the said toner receiving member and the cleaning roller against.   The cleaning device according to claim 1, wherein the toner receiving member is a bowl-shaped member along a peripheral surface of the cleaning roller.   The cleaning roller and the toner receiving member are in contact with each other at a position on the end portion side of the toner receiving member that extends in the circumferential direction of the cleaning roller so as to be away from the contact position between the image carrier and the cleaning roller. The cleaning device according to claim 1 or 2, wherein   4. The cleaning device according to claim 1, wherein the toner receiving member has a friction coefficient with the toner on the surface thereof 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 6, wherein a surface of the image carrier is charged by a charging roller.

Images