JP5114851B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as a copying machine or a printer that employs an electrophotographic system.

  Conventionally, as a charging device for an image forming apparatus such as a copying machine or a printer adopting an electrophotographic method, a device using a corona discharge phenomenon such as a scorotron charger has been widely used, but a charging device using a corona discharge phenomenon is used. In this case, the generation of ozone and nitrogen oxides that have a negative effect on the human body and the global environment is a problem. On the other hand, the contact charging method in which the conductive charging roll is directly contacted with the image carrier to charge the image carrier has significantly less generation of ozone and nitrogen oxide, and the power supply efficiency is good. Recently it has become mainstream.

  Such a charging device of the contact charging method has a disadvantage that various deposits on the image bearing member are adsorbed and easily contaminated during charging. On the other hand, in Patent Document 1, as a cleaning member for the charging roll, a cleaning brush composed of a plurality of brushes extending radially from the shaft is provided and brought into contact with the charging roll.

  The shaft is provided with a region where the cleaning brush is not provided within a predetermined angle, and a non-contact portion and a contact portion are provided between the shaft and the charging roll. During cleaning of the charging roll, the contact portion of the cleaning brush comes into contact with the charging roll, so that the charging roll can be prevented from being broken and surface filming can be suppressed, and foreign matters on the surface of the charging roll can be removed over a long period of time.

  However, in some cases, a small-diameter metal shaft is used as the cleaning member from the viewpoint of size restrictions and cost of the image forming apparatus. In this case, a phenomenon that becomes particularly noticeable is the phenomenon that the amount of deflection of the shaft increases.

  When the shaft is supported at both ends and presses the charging roll, the shaft of the cleaning member bends due to the reaction force that the cleaning brush receives from the charging roll, and the amount of biting at the center of the charging roll decreases. When the amount of biting in the central part of the charging roll is reduced, there arises a problem that the cleaning performance in the central part is lowered.

On the other hand, in order to ensure the cleanability of the central portion of the charging roll, in a state where the biting of the brush is sufficiently secured, the biting at both ends of the charging roll is enormous, resulting in an increase in resistance at both ends of the charging roll, Troubles such as the occurrence of streaks on the print sample occur, and the life of the charging roll is shortened.
JP 2002-196568 A

  In view of the above facts, an object of the present invention is to provide an image forming apparatus capable of obtaining a good cleaning performance of a charging roll by a cleaning member.

In order to achieve the above object, the invention according to claim 1 is an image forming apparatus comprising: an image carrier that carries an image; a charging roll that charges the image carrier; a cleaning means for cleaning the charging roller, wherein the cleaning means, the charging roller and the cleaning roller abutting, they are arranged along the longitudinal direction of the cleaning roller, the case member for supporting both ends of the cleaning roller And a moving means for bringing the case member into and out of contact with the charging roll, separating the cleaning roll from the charging roll during image formation, and bringing the cleaning roll into contact with the charging roll during cleaning. but is connected to the case member, before the case member supply during image formation in a state of oN A solenoid that is separated from the charging roll and whose power is turned off at the time of cleaning and a central portion of the case member are urged toward the charging roll, and the solenoid is compressed against the urging force when the solenoid is on. And an urging means for urging the case member toward the charging roll in a state where the solenoid is OFF .

According to the first aspect of the present invention, the case member is disposed along the longitudinal direction of the cleaning roll that comes into contact with the charging roll, and both ends of the cleaning roll are supported by the case member . The case member can be brought into and out of contact with the charging roll by the moving means, the cleaning roll is separated from the charging roll during image formation, and the cleaning roll is brought into contact with the charging roll during cleaning .

For example, by disposing the respective supporting member spring for supporting both ends of the cleaning roller, if you choose to bias the cleaning roller to the charging roll side, by the load variation of the spring, the left and right axial cleaning roller The pressing force on the charging roll may be different. In this case, change the pressing force and the pressing state in the axial direction of the cleaning roller to the charging roll, a problem that can not be uniformly cleaned in the axial direction of the cleaning roller is concerned.

However, the load variation in the axial direction of the cleaning roll can be reduced by supporting both ends of the cleaning roll on the case member and moving the case member itself by the moving means. Thereby, the variation in the amount of biting into the charging roll can be reduced in the axial direction of the cleaning roll , and a stable cleaning performance can be obtained.

Further, during image formation away cleaning roll from the charging roller, in order to contact the cleaning roller only when cleaning the charging roller, as compared with the case where the cleaning roller is in contact with the constant charging roll, a cleaning roll life Can be achieved.

On the other hand, the urging means abuts against the central portion of the case member and urges the case member toward the charging roll. Further, a solenoid is connected to the case member, and the case member is moved in a direction against the urging means when the power is turned on during image formation.

And at the time of cleaning, the power supply of a solenoid will be in the OFF state. For this reason, the case member is in a free state, and only the urging force of the urging means acts on the case member. That is, the case member is urged toward the charging roll by the urging means, and the cleaning roll comes into contact with the charging roll.

According to a second aspect of the invention, in the image forming apparatus according to claim 1, characterized in that it is larger than both end portions of the cleaning roller outer diameter of the central portion of the front Symbol cleaning roll.

Supporting the cleaning roll in the shaft, when pressing the charging roller with the cleaning roll, the shaft is bent by the reaction force of the cleaning roller receives from the charging roller, but the amount of bite of the central portion of the charging roller is reduced, according to claim 2 In the above-described invention, by making the outer diameter dimension of the central portion of the cleaning roll larger than the both end portions of the cleaning roll in advance, the contact force of the central portion of the cleaning roll with the charging roll becomes larger than both end portions. Thereby, the variation in the amount of biting into the charging roll in the axial direction of the cleaning roll can be further reduced, and the cleaning performance can be improved.

The invention of claim 3 is the image forming apparatus according to claim 1, with respect to the axis of the front Symbol charging roll, characterized in that cross the axis of the cleaning roller.

According to the third aspect of the present invention, the axis of the cleaning roll intersects the axis of the charging roll so that the axis alignment is deviated and the cleaning roll is wound around the charging roll by the amount of deflection at the center of the cleaning roll. Therefore, the nip width can be made uniform in the axial direction of the cleaning roll. Thereby, the cleaning performance by the cleaning roll can be improved.

  Since the present invention has the above-described configuration, it is possible to obtain good cleaning performance of the charging roll by the cleaning roll.

  An image forming apparatus according to an embodiment of the present invention will be described below with reference to the drawings.

  An image forming apparatus 10 according to this embodiment shown in FIG. 1 is a four-cycle full-color laser printer. As shown in the drawing, in the apparatus, a photosensitive drum 12 (image carrier) is located slightly above the center. ) Is rotatably arranged. As this photosensitive drum 12, for example, a drum made of a conductive cylinder having a diameter of about 47 mm and coated on a surface with a photosensitive layer made of OPC or the like is used. It is rotationally driven at a process speed of 150 mm / sec.

  The surface of the photosensitive drum 12 is charged to a predetermined potential by a charging roll 14 disposed almost directly below the photosensitive drum 12, and then exposed to a laser beam LB by an exposure device 16 disposed below the charging roll 14. Image exposure is performed, and an electrostatic latent image according to image information is formed.

  The electrostatic latent image formed on the photosensitive drum 12 has yellow (Y), magenta (M), cyan (C), and black (K) developing devices 18Y, 18M, 18C, and 18K in the circumferential direction. The toner is developed by a rotary developing device 18 disposed along the toner image to form a toner image of a predetermined color.

  At this time, charging, exposure, and development processes are repeated a predetermined number of times on the surface of the photosensitive drum 12 in accordance with the color of the image to be formed. In the developing process, the rotary developing device 18 rotates, and the corresponding color developing devices 18Y, 18M, 18C, and 18K move to a developing position facing the photosensitive drum 12.

  For example, when a full-color image is formed, the charging, exposing, and developing processes are performed on the surface of the photosensitive drum 12 in yellow (Y), magenta (M), cyan (C), and black (K) colors. The toner image corresponding to each color of yellow (Y), magenta (M), cyan (C), and black (K) is sequentially formed on the surface of the photosensitive drum 12. When the toner image is formed, the number of rotations of the photosensitive drum 12 varies depending on the size of the image. For example, in the case of A4 size, one image is obtained by rotating the photosensitive drum 12 three times. It is formed. That is, a toner image corresponding to each color of yellow (Y), magenta (M), cyan (C), and black (K) is formed on the surface of the photosensitive drum 12 every time the photosensitive drum 12 rotates three times. Is done.

  An intermediate transfer belt 20 is wound around the outer periphery of the photosensitive drum 12 for yellow (Y), magenta (M), cyan (C), and black (K) toner images sequentially formed on the photosensitive drum 12. At the primary transfer position, the images are transferred onto the intermediate transfer belt 20 by the primary transfer roll 22 while being superimposed on each other.

  The yellow (Y), magenta (M), cyan (C), and black (K) toner images transferred in multiple onto the intermediate transfer belt 20 are recorded on a recording sheet 24 fed at a predetermined timing. The images are collectively transferred by the secondary transfer roll 26.

  On the other hand, the recording paper 24 is fed out from a paper feed cassette 28 disposed at the lower part of the image forming apparatus 10 by a pickup roll 30 and is fed in a state of being fed one by one by a feed roll 32 and a retard roll 34. The toner image is transferred to the secondary transfer position of the intermediate transfer belt 20 in synchronization with the toner image transferred onto the intermediate transfer belt 20 by the registration roll 36.

  The intermediate transfer belt 20 includes a wrap-in roll 38 that specifies the wrap position of the intermediate transfer belt 20 on the upstream side in the rotational direction of the photosensitive drum 12 and a toner image formed on the photosensitive drum 12 as an intermediate transfer belt. A primary transfer roll 22 that is transferred onto the intermediate transfer belt 20, a wrap-out roll 40 that specifies the wrap position of the intermediate transfer belt 20 on the downstream side of the wrap position, and a backup that contacts the secondary transfer roll 26 via the intermediate transfer belt 20. The roll 42, the first cleaning backup roll 46 facing the cleaning device 44 of the intermediate transfer belt 20, and the second cleaning backup roll 48 are stretched with a predetermined tension, and have a predetermined process speed (about 150 mm / sec), for example, as the photosensitive drum 12 rotates. It is driven Te.

  Here, in order to reduce the size of the image forming apparatus 10, the intermediate transfer belt 20 is configured such that a cross-sectional shape on which the intermediate transfer belt 20 is stretched is a flat and elongated substantially trapezoidal shape.

  The intermediate transfer belt 20 includes a photosensitive drum 12, a charging roll 14, an intermediate transfer belt 20, a plurality of rolls 22, 38, 40, 42, 46, and 48 that stretch the intermediate transfer belt 20, and an intermediate transfer belt. The cleaning device 44 for 20 and the cleaning device 78 for the photosensitive drum 12 described later integrally form an image forming unit 52. Therefore, the entire image forming unit 52 can be removed from the image forming apparatus 10 by opening the upper cover 54 of the image forming apparatus 10 and lifting the handle (not shown) provided on the upper part of the image forming unit 52 by hand. It has become.

  On the other hand, the cleaning device 44 for the intermediate transfer belt 20 includes a scraper 58 disposed so as to come into contact with the surface of the intermediate transfer belt 20 stretched by the first cleaning backup roll 46, and a second cleaning backup roll 48. And a cleaning brush 60 disposed so as to be in pressure contact with the surface of the stretched intermediate transfer belt 20. Residual toner and paper dust removed by the scraper 58 and the cleaning brush 60 are contained in the cleaning device 44. It has come to be collected.

  The cleaning device 44 is disposed so as to be able to swing counterclockwise in the drawing with the swing shaft 62 as the center. Until the secondary transfer of the final color toner image is completed, the intermediate transfer belt is provided. It is configured to retreat to a position separated from the surface of the surface 20 and to contact the surface of the intermediate transfer belt 20 when the secondary transfer of the final color toner image is completed.

  Further, the recording paper 24 onto which the toner image has been transferred from the intermediate transfer belt 20 is conveyed to a fixing device 64 and is heated and pressurized by the fixing device 64 to fix the toner image on the recording paper 24. Thereafter, in the case of single-sided printing, the recording paper 24 on which the toner image has been fixed is discharged as it is onto a discharge tray 68 provided at the top of the image forming apparatus 10 by a discharge roll 66.

  On the other hand, in the case of double-sided printing, the recording paper 24 on which the toner image is fixed on the first surface (front surface) by the fixing device 64 is not directly discharged onto the discharge tray 68 by the discharge roll 66 but is discharged by the discharge roll 66. With the rear end portion of the recording paper 24 being held, the discharge roller 66 is reversed, the conveyance path of the recording paper 24 is switched to the double-sided paper conveyance path 70, and the double-sided paper conveyance path 70 is disposed. In the state where the front and back of the recording paper 24 are reversed by the transport roller 72 thus transferred, the recording paper 24 is again transported to the secondary transfer position of the intermediate transfer belt 20 and the toner image is transferred to the second surface (back surface) of the recording paper 24. . Then, the toner image on the second surface (back surface) of the recording paper 24 is fixed by the fixing device 64, and the recording paper 24 is discharged onto the discharge tray 68.

  Furthermore, a manual feed tray 74 can be attached to the side surface of the image forming apparatus 10 so as to be freely opened and closed. An arbitrary size and type of recording paper 24 placed on the manual feed tray 74 is fed by a paper feed roll 76, and a secondary transfer position of the intermediate transfer belt 20 via a transport roll 73 and a registration roll 36. The image can be formed on the recording paper 24 of any size and type.

  The surface of the photosensitive drum 12 after the toner image transfer process is completed is cleaned by the cleaning blade 80 of the cleaning device 78 disposed obliquely below the photosensitive drum 12 every time the photosensitive drum 12 rotates once. Residual toner, paper dust, and the like are removed to prepare for the next image forming process.

  As shown in FIG. 2, a charging roll 14 is disposed below the photosensitive drum 12 so as to be in contact with the photosensitive drum 12. The charging roll 14 has a conductive layer 14B formed around a conductive shaft 14A, and the shaft 14A is rotatably supported.

  A roll-shaped cleaning roll 100 that is in contact with the surface of the charging roll 14 is provided at a lower portion of the charging roll 14 opposite to the photosensitive drum 12. The cleaning roll 100 has a sponge layer 100B formed around a shaft 100A, and the shaft 100A is rotatably supported (described later).

  The cleaning roll 100 is pressed against the charging roll 14 with a predetermined load, and the sponge layer 100 </ b> B is elastically deformed along the peripheral surface of the charging roll 14 to form the nip portion 101. The photosensitive drum 12 is driven to rotate clockwise (in the direction of arrow 2) in FIG. 2 by a motor (not shown), and the charging roll 14 is driven to rotate in the direction of arrow 4 as the photosensitive drum 12 rotates. Further, the roll-shaped cleaning roll 100 is driven to rotate in the direction of the arrow 6 as the charging roll 14 rotates.

  Further, a charging power source is connected to the charging roll 14, and only a bias in which an alternating current is superimposed on a direct current or a direct current bias is applied. The cleaning roll 100 has the same potential as the charging roll 14.

  As the cleaning roll 100 is driven to rotate, dirt (foreign matter) such as toner and external additives attached to the surface of the charging roll 14 is cleaned by the cleaning roll 100. Then, when the foreign matter is taken into the cell of the sponge layer 100B and the foreign matter collected in the cell is aggregated to an appropriate size, it is returned from the cleaning roll 100 to the photosensitive drum 12 via the charging roll 14, It is considered that the cleaning performance is continuously maintained by being collected by the cleaning device 78 that cleans the photosensitive drum 12.

  In such a cleaning roll 100, free-cutting steel, stainless steel, or the like is used as the material of the shaft 100A, and the material and the surface treatment method are appropriately selected according to applications such as slidability. In addition, a non-conductive material may be processed by a general process such as a plating process and subjected to a conductive process, or may be used as it is. Further, since the cleaning roll 100 comes into contact with the charging roll 14 through the sponge layer 100B with an appropriate nip pressure, the shaft diameter having sufficient rigidity with respect to a material having a low bending strength or a shaft length. Is selected.

  The sponge layer 100B is formed of a foam having a cylindrical shape and a porous three-dimensional structure. The sponge layer 100B is selected from those made of a foamable resin or rubber such as polyurethane, polyethylene, polyamide, or polypropylene. The sponge layer 100B efficiently cleans foreign substances such as external additives by driven sliding rubbing with the charging roll 14, and at the same time does not damage the surface of the charging roll 14 due to rubbing of the sponge layer 100B. In order to prevent tearing and breakage, it is particularly preferable to use polyurethane that is strong in tearing and tensile strength. Note that the cleaning member of the cleaning roll 100 may be configured by a blade, a brush, a waste, or the like other than the sponge.

  The charging roll 14 is formed by sequentially forming a conductive elastic layer and a surface layer as a charging layer 14B on a conductive shaft 14A.

  As the material of the shaft 14A, free-cutting steel, stainless steel or the like is used, and the material and the surface treatment method are appropriately selected according to the use such as slidability, and the material having no conductivity is generally plated. It may be processed by an appropriate process and a conductive process may be performed.

  The conductive elastic layer constituting the charging layer 14B of the charging roll 14 may be, for example, an elastic material such as rubber having elasticity, a conductive material such as carbon black or ionic conductive material for adjusting the resistance of the conductive elastic layer, or the like. Accordingly, materials that can be usually added to rubber, such as softeners, plasticizers, curing agents, vulcanizing agents, vulcanization accelerators, anti-aging agents, and fillers such as silica and calcium carbonate, may be added. It is formed by coating the peripheral surface of the conductive shaft 14 </ b> A with a mixture in which materials usually added to rubber are added. As a conductive agent for the purpose of adjusting the resistance value, a material in which a material that conducts electricity using electrons and / or ions as a charge carrier, such as carbon black or an ionic conductive agent blended in a matrix material, is used. it can. The elastic material may be a foam.

  The surface layer constituting the charging layer 14B is formed for the purpose of preventing contamination by foreign matters such as toner, and the surface layer material may be any of resin, rubber, etc. It is not limited. Polyester, polyimide, copolymer nylon, silicone resin, acrylic resin, polyvinyl butyral, ethylene tetrafluoroethylene copolymer, melamine resin, fluoro rubber, epoxy resin, polycarbonate, polyvinyl alcohol, cellulose, polyvinylidene chloride, polyvinyl chloride, polyethylene And ethylene vinyl acetate copolymer.

  The surface layer can contain a conductive material to adjust the resistance value. The conductive material preferably has a particle size of 3 μm or less.

  In addition, as a conductive agent for the purpose of adjusting the resistance value, it electrically conducts electrons and / or ions as charge carriers, such as carbon black, conductive metal oxide particles, or ionic conductive agent blended in the matrix material. What disperse | distributed material etc. can be used.

  The conductive metal oxide particles, which are conductive particles for adjusting the resistance value, are conductive particles such as tin oxide, tin oxide doped with antimony, zinc oxide, anatase titanium oxide, and ITO. Any conductive agent using electrons as charge carriers can be used without any particular limitation. These may be used alone or in combination of two or more. Any particle size may be used as long as the present invention is not inhibited. From the viewpoint of resistance value adjustment and strength, tin oxide, antimony-doped tin oxide, and anatase-type titanium oxide are preferable. Tin oxide and antimony-doped tin oxide are preferred.

  By performing resistance control with such a conductive material, the resistance value of the surface layer does not change depending on environmental conditions, and stable characteristics can be obtained.

  Further, a fluorine-based or silicone-based resin is used for the surface layer. In particular, it is preferably composed of a fluorine-modified acrylate polymer. Further, fine particles may be added to the surface layer. As a result, the surface layer becomes hydrophobic and acts to prevent the adhesion of foreign matter to the charging roll 14. In addition, insulating particles such as alumina and silica are added to give unevenness to the surface of the charging roll 14, thereby reducing the burden at the time of rubbing against the photosensitive drum 12, and the charging roll 14 and the photosensitive drum. It is also possible to improve the mutual wear resistance.

  Next, the mounting structure of the charging roll 14 and the cleaning roll 100 will be described in detail.

  As shown in FIGS. 3A and 3B, in this embodiment, the photosensitive drum 12 and the charging roll 14 can be assembled to the frame 120. Bearing holes 120A and 120B are formed in the frame 120 at predetermined intervals, and support portions 12a provided at both ends of the shaft 12A of the photosensitive drum 12 are rotatably supported in the bearing holes 120A. In the bearing hole 120B, support portions 14a provided on both ends of the shaft 14A of the charging roll 14 are rotatably supported.

  The frame 120 accommodates a case 140 formed by bending both ends of the plate material upward, and can be disposed along the longitudinal direction of the charging roll 14. A shaft plate 144 is erected on the inner side of both side walls 140A of the case 140 in parallel with the side wall 140A. A bearing hole 144A is formed in the shaft plate 144, and is formed at the end of the shaft 100A of the cleaning roll 100. The provided support portion 100a is rotatably supported.

  Here, the case 140 is formed of a synthetic resin material such as polyacetal or polycarbonate having high rigidity, high slidability, and excellent wear resistance. In order to further improve the wear resistance, the synthetic resin material may contain glass fibers, carbon fibers, or the like.

  Further, a compression coil spring 146 (moving means) is disposed at the center of the back surface of the case 140, and urges the case 140 toward the charging roll 14 side. Further, connecting portions 148 are respectively provided on the outer surfaces of both side walls 140A of the case 140, and a solenoid 142 (moving means) fixed to the upper surface of a pedestal 120C formed by bending the lower end portion of the frame 120. The pin 150 is connected. The pin 150 is drawn into the main body 152 when the solenoid 142 is ON (see FIG. 3B), and in the OFF state, the pulling force is released (FIG. 3A). reference).

  At the time of image formation, as shown in FIG. 3B, the solenoid 142 is turned on, the pin 150 is drawn into the main body 152, and the case 140 moves downward via the pin 150 and the connecting portion 148. The compression coil spring 146 is compressed.

  Further, at the time of cleaning, as shown in FIG. 3A, the solenoid 142 is turned off, the pin 150 is free, and only the urging force by the compression coil spring 146 acts on the case 140. It becomes. Therefore, the case 140 is urged toward the charging roll 14 by the urging force of the compression coil spring 146, and the sponge layer 100 </ b> B comes into contact with the charging roll 14. As described above, the sponge layer 100B is elastically deformed along the peripheral surface of the charging roll 14 to form the nip portion 101 (see FIG. 2).

  Thus, when the photosensitive drum 12 rotates, the charging roll 14 is driven to rotate with the rotation of the photosensitive drum 12 to charge the photosensitive drum 12, and further, the cleaning roll 100 is driven to rotate with the rotation of the charging roll 14. Then, the charging roll 14 is cleaned.

  Next, the operation of this embodiment will be described.

  As shown in FIGS. 3A and 3B, a support portion 100 a provided at the end of the shaft 100 </ b> A of the cleaning roll 100 is pivotally supported on the shaft plate 144 of the case 140, and the solenoid 142 and the compression coil spring 146 are used. The case 140 is brought into and out of contact with the charging roll 14.

  For example, although not shown, when the springs are respectively disposed at both ends of the shaft 100A of the cleaning roll 100 and the sponge layer 100B is urged toward the charging roll 14, the sponge layer is caused by variations in the spring load. The pressing force to the charging roll 14 is different between the left and right in the axial direction of 100B. In this case, there is a concern that the pressing force or pressing state against the charging roll 14 changes in the axial direction of the sponge layer 100B, and the cleaning cannot be performed uniformly in the axial direction of the sponge layer 100B.

  However, both ends of the shaft 100 </ b> A of the cleaning roll 100 are pivotally supported by the case 140, and the case 140 itself is interposed via the connecting portion 148 and the pin 150 in a state where the compression coil spring 146 is disposed at the center of the back surface of the case 140. By making it move, case 140 will move horizontally.

  That is, it moves parallel to the charging roll 14, and there is almost no load variation in the axial direction of the sponge layer 100B. Thereby, in the axial direction of the sponge layer 100B, variation in the amount of biting into the charging roll 14 can be reduced, and stable cleaning performance can be obtained.

  Further, the sponge layer 100B is separated from the charging roll 14 during image formation, and the sponge layer 100B is brought into contact with the charging roll 14 only during cleaning. The life of the sponge layer 100B can be extended.

  Here, the sponge layer 100B is cylindrical, but is not limited thereto. When the charging roll 14 is pressed while the shaft 100A is supported at both ends, as shown in FIG. 5A, the shaft 100A bends due to the reaction force that the sponge layer 100B receives from the charging roll 14, and the center of the charging roll 14 As shown in FIG. 5B, the charging roll at the center portion of the sponge layer 102 is made larger in advance than the both end portions, as shown in FIG. The contact force to 14 is made larger than both ends. Thereby, the variation in the amount of biting into the charging roll 14 in the axial direction of the sponge layer 102 can be further reduced, and the cleaning performance can be improved.

  6A to 6E, the axis P of the shaft 100A of the cleaning roll 100 may be disposed so as to intersect the axis Q of the shaft 14A of the charging roll 14. 6 shows the arrangement of the cleaning roll and the charging roll, (A) is a bottom view, (B) is a front view, and (C) to (E) are sectional views of (B).

  As a result, the axial alignment shifts and the sponge layer 100B is wound around the surface of the charging roll 14 by the amount of deflection at the central portion of the shaft 100A, so that the nip width is made uniform in the axial direction of the sponge layer 100B. be able to. Thereby, the cleaning performance by the sponge layer 100B can be improved.

In this embodiment, the cleaning roll 100 is used as the cleaning member and the sponge layer 100B is formed around the shaft 100A. However, the reference example of the present invention is not limited to the roll-like sponge. As shown in FIG. 7, a plate-like sponge member 154 may be used. However, in this case, the sponge member 154 is fixed to a holder 156 provided to face the charging roll 14, and the holder 156 is fixed to the shaft plate 144 of the case 140.

  As mentioned above, although it demonstrated in detail by embodiment of this invention, this invention is not limited to them, Various other forms can be implemented within the scope of the present invention.

  For example, in the present embodiment, the charging roll 14 is brought into contact with the lower part of the photosensitive drum 12 and the cleaning roll 100 is brought into contact with the lower part of the charging roll 14, but the photosensitive drum 12, the charging roll 14, and The positional relationship of the cleaning roll 100 is not limited to this. For example, the present invention can be applied to a configuration in which a charging roll is brought into contact with an upper portion of the photosensitive drum and a cleaning roll is brought into contact with the upper portion of the charging roll. Further, the present invention can be applied even when the charging roll 14 is not in contact with the photosensitive drum 12.

  The image forming apparatus to which the present invention is applied has a four-cycle configuration in which the toner image is formed on the photosensitive drum 12 four times using the rotary developer 18 as in the above-described embodiment. It is not limited to. For example, even if the yellow, magenta, cyan, and black image forming units are arranged in parallel along the moving direction of the intermediate transfer belt, the present invention is applied to the photosensitive drum, the charging roll, and the cleaning roll of each image forming unit. Can be applied.

1 is a configuration diagram illustrating a schematic configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is an enlarged view showing a configuration of a photosensitive drum, a charging roll, and a cleaning roll mounted on the image forming apparatus of FIG. 1. 2A and 2B are partial cross-sectional front views illustrating a configuration of a mounting structure of a photosensitive drum, a charging roll, and a cleaning roll of an image forming apparatus according to an embodiment of the present invention, in which FIG. Is shown. FIG. 5A is a perspective view and FIG. 5B is a side view showing a state in which a charging roll and a cleaning roll constituting an image forming apparatus according to an embodiment of the present invention are supported by a bearing member. (B) is a modification showing the shape of the cleaning roll constituting the image forming apparatus according to the embodiment of the present invention, and (A) is a comparative example for explaining (B). FIG. 6 is a modified example showing the arrangement of the cleaning roll and the charging roll constituting the image forming apparatus according to the embodiment of the present invention, where (A) is a bottom view, (B) is a front view, and (C) to (E) are respectively. It is sectional drawing of (B). FIG. 10 is a partial cross-sectional front view showing a modification of the cleaning means constituting the image forming apparatus according to the reference example of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 12 Photosensitive drum (Image carrier)
14 charging roll 100 cleaning roll 100B sponge layer (cleaning roller)
102 Sponge layer ( cleaning roll )
140 Case (Case member)
142 Solenoid (moving means)
146 Compression coil spring (biasing means, moving means )

Claims (3)

An image carrier that carries an image, a charging roll that charges the image carrier, and a cleaning unit that contacts the charging roll and cleans the charging roll.
The cleaning means
A cleaning roll in contact with the charging roll;
Are arranged along the longitudinal direction of the cleaning roller, and the case member for supporting both ends of the cleaning roller,
Moving means for bringing the case member into and out of contact with the charging roll, separating the cleaning roll from the charging roll during image formation, and bringing the cleaning roll into contact with the charging roll during cleaning ;
With
The moving means is connected to the case member, and a power source is turned on at the time of image formation to separate the case member from the charging roll, and a power source is turned off at the time of cleaning, and a solenoid of the case member Urging means for urging the central portion toward the charging roll, compressing the urging force against the urging force when the solenoid is on, and urging the case member toward the charging roll when the solenoid is off; an image forming apparatus characterized by being configured to include. The image forming apparatus according to claim 1, characterized in that it is larger than both end portions of the cleaning roller outer diameter of the central portion of the front Symbol cleaning roll. Relative to the axis of the front Symbol charging roll, the image forming apparatus according to claim 1, characterized in that cross the axis of the cleaning roller.

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