JP2011227456A - Charging device and image formation device having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charging device that can uniformly remove dirt adhered to a charging roller to obtain a favorable image and simplify a driving mechanism of a cleaning member, and an image formation device having the same.SOLUTION: A charging device 40 includes: a charging roller 71 that electrifies a photoreceptor 38; a cleaning member 81 that contacts with a surface of the charging roller 71 to clean the same; and a driving mechanism 80 that rotatively drives the cleaning member 81 against the charging roller 71 with a linear velocity difference and reciprocatingly drives the same along the axial direction. The driving mechanism 80 includes: a motive power shaft member 85 having an input side gear 87 that engages with an output side gear 84 provided in the cleaning member 81 and a worm 88 that is provided coaxially with the input side gear 87; and a cam member 95 having a worm wheel 97 that engages with the worm 88 and an eccentric cam 98 that is pressed toward the axial direction side of the cleaning member 81 and displaces the cleaning member 81 in the axial direction by the rotation of the worm wheel 97.

Description

  The present invention relates to a charging device used for an image forming apparatus such as a copying machine, a printer, a facsimile, and a composite machine using an electrophotographic system, and an image forming apparatus including the charging device, and more particularly, has a mechanism for cleaning a charging roller. The present invention relates to a charging device and an image forming apparatus including the charging device.

  Conventionally, in an image forming apparatus using an electrophotographic system, a charging device is used to charge the surface of a photoconductor as an image carrier. As a charging device, a photoconductor and a corona wire are disposed in a non-contact manner, and a corona charging method in which the surface of the photoconductor is charged by corona discharge, and a contact charging in which the surface of the photoconductor is contacted using a charging member such as a charging roller. The method is known. However, in recent years, in order to reduce the amount of ozone that is harmful to the human body, a contact charging method with a smaller amount of ozone emission has been increasingly adopted.

  When the charging roller is brought into contact with the surface of the photosensitive member in such a contact charging method, foreign matters such as toner components and paper dust may adhere to the surface of the photosensitive member, and the foreign matter may move to the surface of the charging roller. . If a foreign matter adheres to the surface of the charging roller, a charging failure occurs on the surface of the photosensitive member, which greatly affects the image quality of printing. In order to prevent such foreign matter from adhering to the charging roller, conventionally, a cleaning member such as a sponge is pressed against the surface of the charging roller to wipe off dirt due to the foreign matter adhering to the charging roller.

  However, if the cleaning member is made of a member such as a sponge, a part of the charging roller is left unwiped, and charging defects due to streaky dirt on the charging roller cannot be prevented, affecting the print image quality. There was a problem.

  Therefore, in Patent Document 1, the cleaning member is driven to rotate with a linear velocity difference with respect to the charging roller, and dirt on the charging roller is removed by reciprocating in the axial direction of the charging roller. Specifically, this charging device is provided with a gear on one shaft portion of the cleaning member, and this gear meshes with the gear of the photosensitive drum via an idle gear, and cleaning is performed in synchronization with the rotation of the photosensitive drum. The member is driven to rotate. In addition, a disc-shaped cam inclined in the axial direction is provided on the other shaft portion of the cleaning member, and this disc-shaped cam fits into a recess provided in the apparatus main body, and cleaning is performed as the cleaning member rotates. The member is guided by a disc-shaped cam and reciprocally driven in the axial direction to clean the charging roller.

JP 2007-24212 (paragraphs [0031] to [0033], [0038] to [0042], FIGS. 8 and 10)

  However, in the above-described prior art, when the cleaning member rotates once, it reciprocates in the axial direction, and the axial reciprocation is frequently performed with respect to the rotational drive of the cleaning member. When the cleaning member rapidly reciprocates as described above, vibrations of the reciprocating movement of the cleaning member are transmitted to the photosensitive member connected via the gears of the cleaning member and the photosensitive drum, and the rotational driving torque of the photosensitive member fluctuates. There is a fear. Due to the torque fluctuation of the photosensitive drum, the linear velocity of the photosensitive member becomes unstable, and there is a problem that band-like density unevenness occurs in the image. In addition, a mechanism for rotationally driving the cleaning member and a mechanism for reciprocally driving the cleaning member are separately provided on both sides of the cleaning member, which complicates the driving mechanism of the cleaning member and increases the number of parts constituting the driving mechanism. there were.

  SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems. A charging device that uniformly removes dirt adhering to the charging roller and obtains a good image and simplifies the drive mechanism of the cleaning member. An object of the present invention is to provide an image forming apparatus including the same.

  In order to achieve the above object, the first invention provides a charging roller for charging an image carrier, a cleaning member for cleaning the charging roller in contact with the surface of the charging roller, and the cleaning member as the charging roller. A driving mechanism that is driven to rotate with a linear velocity difference and is driven to reciprocate along an axial direction. The driving mechanism is meshed with an output side gear provided in the cleaning member. A driving shaft member having a gear and a worm provided coaxially with the input side gear; a worm wheel meshing with the worm; and an axial direction of the cleaning member, and the cleaning member being rotated by the rotation of the worm wheel. A cam member having an eccentric cam that is displaced in a direction; and a biasing member that biases the cleaning member in the direction of the cam member. That.

  According to this configuration, when the driving shaft member is driven to rotate, the cleaning member rotates due to the rotation of the input side and output side gears, and the eccentric cam of the cam member rotates at a reduced speed due to the engagement of the worm and the worm wheel. In accordance with the displacement of the eccentric cam, the cleaning member reciprocates in the axial direction relatively slowly with respect to its rotation.

  According to a second aspect of the present invention, the eccentric cam is brought into pressure contact with the side surface of the input side gear by the biasing force of the biasing member.

  According to a third aspect of the invention, the drive mechanism is rotatably supported on one end side in a case member that supports the charging roller.

  According to a fourth aspect of the present invention, the input side gear meshes with a drum side gear provided on the image carrier. According to this configuration, the input side gear meshes with the output side gear provided on the cleaning member and also meshes with the drum side gear that is a drive source.

  In the fifth aspect of the invention, the case member is made of resin, the shaft portion of the cam member is rotatably fitted and one end is opened, and at least one of the long hole portions. A predetermined gap is formed between a protrusion formed so as to protrude from the side surface and a part of the outer peripheral surface of the shaft portion rotatably contacts with an inner surface on which at least the protrusion is formed in the width direction of the long hole portion. And a hole formed with a gap therebetween.

  In the sixth invention, the hole portion is elongated along the long hole portion, and the long hole portion is at least as the surface on the side close to the projection portion moves toward the open side of the long hole portion. It is characterized in that it is formed to be inclined so as to be close to.

  According to a seventh aspect of the invention, there is provided an image forming apparatus equipped with the charging device having the structure described above.

  According to the first invention, when the driving shaft member is driven to rotate, the cleaning member is rotated by the rotation of the input side and output side gears, and the eccentric cam of the cam member is decelerated and rotated by the engagement of the worm and the worm wheel. In response to the displacement of the eccentric cam, the cleaning member reciprocates in the axial direction relatively slowly with respect to its rotation. Therefore, since the cleaning member rotates and reciprocates slowly in the axial direction, there is no risk of uneven rotation of the drive mechanism, and the image carrier rotates stably, and image defects such as band-shaped density unevenness occur. Therefore, the dirt attached to the charging roller can be removed well. Furthermore, the drive mechanism unit that drives the cleaning member can be reduced in the number of constituent members, has a simple configuration, and does not increase in size.

  According to the second invention, the eccentric cam is pressed against the side surface of the input side gear by the biasing force of the biasing member, and when the eccentric cam rotates, the cleaning member reciprocates in the axial direction. There is no need to provide a member such as a cam follower that presses against the eccentric cam, and the cleaning member can be reliably reciprocated in the axial direction.

  According to the third aspect of the invention, the driving mechanism is rotatably supported at one end side in the case member that supports the charging roller, so that the charging device does not become bulky.

  According to the fourth aspect of the invention, the input side gear meshes with the output side gear provided on the cleaning member and also meshes with the drum side gear that is a drive source, so that the drive mechanism section does not increase in size.

  According to the fifth aspect of the present invention, when the shaft portion of the cam member is inserted into the elongated hole portion of the case member and then the shaft portion is pushed into the protrusion portion, the vicinity of the protrusion portion is elastically deformed. The shaft portion of the member gets over the protrusion and is rotatably supported by the fitting portion and the protrusion of the long hole portion. Therefore, the cam member can be easily attached to the case member, and the shaft portion of the cam member can be reliably supported by the case member.

  According to the sixth invention, the hole of the case member is formed to be inclined so as to approach the long hole as it goes toward the open side of the long hole, so that the open side near the hole is elastically deformed. When the shaft portion of the cam member is pushed into the projection portion of the case member, the shaft portion easily gets over the projection portion. For this reason, it can attach to a case member, without damaging the axial part of a cam member, and can support the axial part of a cam member to a case member reliably.

  According to the seventh aspect of the invention, it is possible to obtain an image forming apparatus including a charging device in which dirt attached to the charging roller is uniformly removed to obtain a good image and the driving mechanism of the cleaning member is simplified. it can.

1 is a diagram showing a schematic configuration of an image forming apparatus equipped with a charging device according to an embodiment of the present invention. The perspective view which shows the charging device which concerns on this embodiment A plan view of a part of the charging device according to this embodiment. The side view which shows the supporting member of the charging device which concerns on this embodiment The perspective view which shows the drive mechanism part of the charging device which concerns on this embodiment. The top view which shows the structure which supports the cam member of the drive mechanism part which concerns on this embodiment. The top view which shows the modification of the support structure of the cam member which concerns on this embodiment The top view which shows the drive mechanism part of the charging device which concerns on this embodiment.

  Embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited to these embodiments. Further, the use of the invention and the terms shown here are not limited thereto.

  FIG. 1 is a diagram illustrating an in-body discharge type image forming apparatus. An arrow indicated by a solid line indicates a conveyance direction and a conveyance path of the paper P or the original, and an arrow indicated by a one-dot chain line indicates a light beam irradiated on the photosensitive member.

  A cassette type paper feeder 14 is disposed at the lower part of the image forming apparatus 10. The paper feed unit 14 includes upper and lower two-stage paper feed cassettes 16a and 16b, and the paper P before printing is stacked and accommodated in the paper feed cassettes 16a and 16b. The paper P stored in the paper feed cassettes 16a and 16b is fed out one by one by the pickup roller 18a (18b) from the selected paper feed cassette 16a (16b), and the fed paper P is a pair of paper feed rollers 20a. , 20b to the sheet conveyance path L1.

  A manual feed tray 22 is disposed on the right side surface of the image forming apparatus 10. When the manual feed tray 22 is opened from the closed state shown in FIG. 1 and is in the horizontal position, the paper P having a size different from that of the paper feed cassettes 16 a and 16 b can be placed on the manual feed tray 22. The paper P placed on the manual feed tray 22 is fed out one by one by the pickup roller 24, and the fed paper P is sent out to the paper transport path L2 by the pair of paper feed rollers 26a and 26b.

  The paper transport path L1 includes a plurality of transport rollers 28 and is disposed on the left side of the paper feed cassettes 16a and 16b. The paper P sent out from the paper feed cassettes 16 a and 16 b is transported upward by the transport rollers 28 in the paper transport path L 1 and sent to the image transfer unit 36. The sheet conveyance path L <b> 2 includes a plurality of conveyance rollers 30 and is disposed on the left side of the manual feed tray 22. The paper P sent out from the manual feed tray 22 is transported substantially horizontally by the transport roller 30 in the paper transport path L <b> 2 and is sent to the image transfer unit 36.

  A registration roller 32 is disposed upstream of the image transfer unit 36 in the paper conveyance direction. The registration roller 32 sends out the paper P toward the image transfer unit 36 in synchronization with the timing of transferring the toner image onto the paper P.

  A document feeding reader 37 is disposed on the upper part of the image forming apparatus 10. When copying a document, the document is placed on the document feeding unit, and the placed documents are separated one by one and sent from the document feeding unit to the document reading unit. Is read.

  An image forming unit 34 is disposed substantially at the center of the image forming apparatus 10. The image forming unit 34 includes a photoconductor 38 that is an image carrier, and further, around the photoconductor 38 along the rotation direction in order, a charging device 40, an exposure device 42, a developing device 44, and a transfer roller. 48 and a cleaning device 46.

  When the surface of the photoreceptor 38 is uniformly charged with a predetermined polarity and potential by the charging device 40, the exposure device 42 is based on the image data of the document read by the document feed reader 37. An electrostatic latent image of the original image is formed on the top.

  The developing device 44 supplies charged toner to the surface of the photoreceptor 38 and develops the electrostatic latent image on the photoreceptor 38 to form a toner image. The toner image is transferred onto the paper P by the transfer roller 48 of the image transfer unit 36. The paper P on which the toner image has been transferred is conveyed to the fixing unit 50 through the paper conveyance path L3. After the toner image is transferred to the paper P, the residual toner remaining on the surface of the photoreceptor 38 is cleaned and collected by the cleaning device 46.

  The fixing device 50 includes a heat roller 52 incorporating a heat source and a pressure roller 54 that presses the heat roller 52. The paper P to which the toner image has been transferred is pressurized and heated by the heat roller 52 and the pressure roller 54, and the toner image on the paper P is melted and fixed. The sheet P on which the toner image is fixed is discharged to the in-body discharge unit 60 by a pair of discharge rollers 58a and 58b.

  The paper P on which the toner image is fixed is switched in the transport direction by the path switching guide 56 as necessary, and is discharged onto the stack tray 62 by the transport rollers 64a and 64b. When performing duplex printing, the discharge rollers 58a and 58b are rotated in reverse at the timing when the trailing edge of the paper P passes through the switching guide 56 during the discharge to the in-cylinder discharge unit 60, and the path switching guide. 56 and 66 are switched to the sheet conveyance path L4 side. As a result, the paper P passes between the transport rollers 68 of the paper transport path L4 and is transported from the paper transport path L1 to the registration rollers 32. Thereafter, when the toner image is transferred to the back surface of the paper P by the image transfer unit 36, the paper P is fixed again by the fixing unit 50 and discharged.

  Next, the charging device 40 used in the above-described image forming apparatus 10 will be described with reference to FIGS. FIG. 2 is a perspective view showing the charging device, FIG. 3 is a plan view showing a left side of the charging device, and FIG. 4 is a side view schematically showing the support member. FIG. 3 is a plan view showing the back side of the charging device 40 of FIG.

  As shown in FIG. 2, the charging device 40 includes a charging roller 71, a cleaning member 81, a drive mechanism unit 80, and a case member 91 that houses the charging roller 71, the cleaning member 81, and the drive mechanism unit 80. Is provided.

  The charging roller 71 is composed of a conductive rubber roller in which an elastic layer such as rubber is formed on the peripheral surface of a metal core. The charging roller 71 is in pressure contact with the photoconductor 38 with a predetermined nip pressure. Followed rotation.

  The cleaning member 81 removes toner adhering to the charging roller 71 and paper dust of the paper, and is made of a rubber or resin sponge-like roller, and extends in the axial direction like the charging roller 71. It is in contact with its surface above 71. Further, the cleaning member 81 is supported rotatably and supported so as to be movable in the axial direction of the charging roller 71. The cleaning member 81 may be formed in a brush shape with a resin such as conductive nylon.

  The case member 91 is formed of a non-conductive resin and has a box shape extending in the axial direction of the charging roller 71, and an opening 91 h is formed on one side surface of the case member 91. One end of a spring member, which will be described later, faces this opening 91h, and one end of the spring member is pressed against a power supply terminal connected to the power supply of the apparatus main body, so that a predetermined voltage can be applied to the charging roller 71. become.

  The drive mechanism unit 80 is disposed on one end side in the case member 91 and is connected to a drum side gear 39 provided on one end side of the photoreceptor 38. When the photosensitive member 38 rotates, the driving mechanism 80 causes the cleaning member 81 to rotate with respect to the charging roller 71 with a linear speed difference and to reciprocate along the axial direction by the rotational driving force of the drum-side gear 39. As a result, toner adhering to the charging roller 71 and paper dust of the paper are removed.

  As shown in FIG. 3, the charging device 40 includes a pair of support members 92 (the right support member 92 is invisible) in addition to the above-described charging roller 71, cleaning member 81, drive mechanism 80, and case member 91. A first spring member 75 and a pair of second spring members 76 (the second spring member 76 on the right side is invisible) are provided, and these members are accommodated in the case member 91.

  The pair of support members 92 are provided on both ends of the charging roller 71 in the axial direction, rotatably support the rotating shaft 74 provided on the charging roller 71, and rotate the shaft member 83 provided on the cleaning member 81. And is supported so as to be movable in the axial direction. A first spring member 75 is disposed outside one support member 92 (left support member 92 in FIG. 3), and outside the other support member 92 (right support member 92 in FIG. 3, invisible). A drive mechanism 80 is provided.

  The first spring member 75 is formed of a coil spring, abuts against the end of the shaft member 83 of the cleaning member 81, and presses the cleaning member 81 toward the drive mechanism 80.

  As shown in FIG. 4, the pair of second spring members 76 is formed of a coil spring, abuts on the upper part of the support member 92 and abuts on the upper wall in the case member 91, and charges the charging roller via the support member 92. 71 is urged toward the surface of the photoreceptor 38. The support member 92 is formed with a bearing hole 92b that rotatably supports the shaft member 83 of the cleaning member 81. Further, the support member 92 is formed with a semicircular bearing portion 92 a having a lower chip, and even if the support member 92 is urged by the second spring member 76, the bearing portion 92 a is a rotating shaft 74 of the charging roller 71. Will be bearing. Further, the support member 92 is formed with a contact surface 92d that contacts the inner wall of the case member 91, and the support member 92 is moved in the horizontal direction of FIG. It is supposed not to move to.

  Therefore, the charging roller 71 is uniformly pressed against the surface of the photoconductor 38 by the urging force of the second spring member 76, the charging roller 71 is driven to rotate as the photoconductor 38 rotates, and the cleaning member 81 is 71 is contacted.

  Further, the support member 92 is made of conductive resin, and one end of the second spring member 76 is extended to the opening 91h (see FIG. 2) of the case member 91, so It is in pressure contact with a power feeding terminal (not shown) connected to. As a result, a predetermined voltage can be applied to the charging roller 71 via the support member 92 and the rotating shaft 74. Note that power may be supplied to the charging roller 71 via the first spring member 75 (see FIG. 3) instead of the one second spring member 76.

  Next, the drive mechanism 80 will be described with reference to FIGS. FIG. 5 is a perspective view showing the drive mechanism. FIG. 6 is a plan view showing a configuration for supporting the cam member of the drive mechanism section, and FIG. 7 is a plan view showing a modification of the support configuration for the cam member. FIG. 8 is a side view showing the drive mechanism. FIG. 5 is a perspective view as seen from the photosensitive member side, and FIG. 8 shows the drive mechanism portion with the case member omitted.

  As shown in FIG. 5, the drive mechanism unit 80 includes a driving shaft member 85 arranged to extend in the same direction as the charging roller 71 and a cam member 95 arranged to intersect the driving shaft member 85.

  The driving shaft member 85 is adjacent to the shaft portion 86 rotatably supported by the case member 91, the input side gear 87 formed around the shaft portion 86, and the input side gear 87 with the same axis. And a worm 88 disposed thereon. The input side gear 87 meshes with an output side gear 84 provided on a shaft member 83 (see also FIG. 8) of the cleaning member 81. The input side gear 87 and the output side gear 84 are spur gears.

  The cam member 95 includes a shaft portion 96 that is rotatably supported by the case member 91, a worm wheel 97 that meshes with the worm 88 of the driving shaft member 85 and is formed around the shaft portion 96, and the same shaft as the worm wheel 97. And an eccentric cam 98 disposed adjacent to the core.

  As shown in FIG. 6, the shaft portion 96 of the cam member 95 is rotatably supported by a long hole portion 91 a and a projection portion 91 d formed in the case member 91.

  The long hole portion 91 a has a width slightly larger than the outer diameter of the shaft portion 96 of the cam member 95 and is formed by a long hole extending from the end surface of the case member 91. A fitting portion 91b is formed in the back of the long hole portion 91a, and a protruding portion 91d is formed on one inner side surface 91c of the long hole portion 91a.

  The fitting portion 91b has a semicircular shape slightly larger than the outer diameter of the shaft portion 96 of the cam member 95, and rotatably supports the shaft portion 96 of the cam member 95.

  The protruding portion 91d is formed so as to protrude in an arc shape from the inner side surface 91c of the elongated hole portion 91a, and abuts against a part of the shaft portion 96 when the shaft portion 96b of the cam member 95 is fitted to the fitting portion 91b. . Therefore, the shaft portion 96 of the cam member 95 is rotatably supported by the fitting portion 91b and the protruding portion 91d.

  In the vicinity of the protrusion 91d of the case member 91, a hole 91e is formed. The hole portion 91e is formed as a through-hole that extends in parallel with the long hole portion 91a including a position facing the protruding portion 91d. By forming the hole portion 91e at an opposing position in the vicinity of the protruding portion 91d, the width of the resin portion between the protruding portion 91d and the hole portion 91e is reduced so that it can be elastically deformed. The hole 91e may be a long hole or a round hole as long as the hole 91e is formed at an opposing position in the vicinity of the protrusion 91d.

  When assembling the cam member 95 to the case member 91, after the shaft portion 96 of the cam member 95 is inserted into the elongated hole portion 91a of the case member 91, the shaft portion 96 is pushed into the protrusion portion 91d. Since the portion is elastically deformed toward the hole 91e, the shaft portion 96 gets over the protrusion 91d and fits into the fitting portion 91b. In a state in which the shaft portion 96 is fitted in the fitting portion 91b, the projection portion 91d returns to the original position and comes into contact with a part of the shaft portion 96, so that the shaft portion 96 of the cam member 95 can rotate to the case member 91. Supported.

  FIG. 7 shows a modification of the hole 91 e of the case member 91. The hole 91e is an elongated through hole formed at a position facing the arc-shaped protrusion 91d in the vicinity of the protrusion 91d. Further, the hole portion 91e has an inclined surface 91f that is inclined so as to approach the long hole portion 91a toward the open side (the lower side in FIG. 7) of the long hole portion 91a. Therefore, the resin portion between the protrusion 91d and the hole 91e is wide on the fitting portion 91b side of the long hole portion 91a, while the width is narrow on the open side of the long hole portion 91a. With this configuration, the resin portion on the open side between the protruding portion 91d and the hole portion 91e is easily elastically deformed. When the shaft portion 96 is pushed into the protruding portion 91d, the shaft portion 96 can easily get over the protruding portion 91d. In addition, when the shaft portion 96 is fitted into the fitting portion 91b, the shaft portion 96 is reliably supported by the fitting portion 91b and the projection portion 91d. In the above modification, the hole 91e is formed such that the other surface of the inclined surface 91f is parallel to the long hole portion 91a. Instead, the other surface is formed as an inclined surface 91f. You may form in the surface which is parallel.

  In the configuration for supporting the cam member 95, the protrusion 91d and the hole 91e of the case member 91 are provided on the inner surface 91c side of the long hole 91a. You may make it the structure provided in both the side surfaces of the part 91a. In this case, the protrusion amount from the side surface of the protrusion 91d is preferably smaller than that in the above embodiment.

  As shown in FIG. 8, the eccentric cam 98 has different distances from the axial center to the outer peripheral edge on the circumference. That is, the distance to the outer peripheral edge per unit rotation angle of the eccentric cam 98 increases at a constant rate, becomes the longest at a rotation angle of 180 degrees, and conversely the distance to the outer peripheral edge when it exceeds 180 degrees. Is formed to be shorter at a constant rate. The displacement of the distance to the outer peripheral edge with respect to the rotation angle is set according to the one-side movement amount of the reciprocating movement of the cleaning member 81.

  Further, the outer peripheral edge of the eccentric cam 98 is disposed so as to face the side surface portion 84a of the output side gear 84, and the output side gear 84 is moved to the eccentric cam 98 side by the first spring member 75 (see FIG. 3). Since it is pressed, the outer peripheral edge of the eccentric cam 98 always comes into contact with the side surface portion 84 a of the output side gear 84. Therefore, when the eccentric cam 98 rotates, the output side gear 84 moves in the axial direction against the urging force of the first spring member 75 (see FIG. 3) according to the phase of the eccentric cam 98, and the shaft member The cleaning member 81 moves in the axial direction via 83. When the eccentric cam 98 is rotated halfway, the cleaning member 81 is moved from one end side in the axial direction to the other end side. When the eccentric cam 98 is further rotated halfway, the cleaning member 81 is reversed from the other end side in the axial direction. Therefore, when the eccentric cam 98 rotates once, the cleaning member 81 reciprocates once.

  Thus, the shaft member 83 provided between the output side gear 84 and the cleaning member 81 slides in the axial direction within the bearing hole 92b provided in the support member 92 as the output side gear 84 moves in the axial direction. To do. Further, when the output side gear 84 is rotated by the input side gear 87, the shaft member 83 of the output side gear 84 rotates in the bearing hole 92 b of the support member 92. The input side gear 87 meshes with the output side gear 84 and also meshes with the drum side gear 39 formed of a spur gear provided on the photosensitive member 38.

  As described above, the support member 92 supports the shaft member 83 of the cleaning member 81 in the bearing hole 92b to be rotatable and slidable, and the rotation shaft 74 of the charging roller 71 to be rotatable in the bearing portion 92a. I support it. Since the bearing portion 92a is formed in a semicircular shape (see also FIG. 4) with a chipped lower side, the toner scatters from the developing device 44 (see FIG. 1) disposed in the vicinity of the charging device 40. There is a possibility that the toner adheres to the rotating shaft 74 of the charging roller 71. If toner adheres to the rotation shaft 74 of the charging roller 71, smooth rotation of the charging roller 71 cannot be obtained. Therefore, a cover member 99 is disposed on the rotation shaft 74 to prevent this.

  The cover member 99 has a cover part 99a and a holding part 99b and is formed of resin. The cover portion 99a is formed in a semicircular shape so as to face the semicircular bearing portion 92a of the support member 92 and further extend to the left and right sides of the bearing portion 92a below the rotating shaft 74 so as to cover the rotating shaft 74. The The holding part 99b is connected to the charging roller 71 side of the cover part 99a and is fitted to the rotating shaft 74. The holding portion 99b is fitted to the rotation shaft 74, whereby the cover member 99 is held so that the cover portion 99a covers the lower side of the rotation shaft 74. The second spring member 76 is fitted into a spring receiver 92 c that protrudes from the upper portion of the support member 92 and is held by the support member 92.

  In the charging device 40 having such a drive mechanism 80, when the photosensitive member 38 (see FIG. 2) rotates, the charging roller 71 is uniformly applied to the surface of the photosensitive member 38 by the urging force of the pair of second spring members 76. Pressed and rotated. Further, when the drum side gear 39 rotates as the photosensitive member 38 rotates, the input side gear 87 that meshes with the drum side gear 39 rotates. The rotational drive of the input side gear 87 is transmitted to the output side gear 84, and the cleaning member 81 is supported by the bearing hole 92b of the support member 92 and rotated by this rotational drive.

  Further, the rotational drive of the input side gear 87 is transmitted to the worm 88, the worm wheel 97 meshing with the worm 88 is decelerated and rotated, and the eccentric cam 98 is also decelerated and rotated integrally. Here, if the reduction ratio between the worm 88 and the worm wheel 97 is 1 / N, the eccentric cam 98 together with the worm wheel 97 is 1 during the period in which the output side gear 84 rotates N due to the rotation of the input side gear 87. Will rotate. Here, the input side gear 87 and the output side gear 84 are rotated at a constant speed.

  When the eccentric cam 98 rotates in this way, the eccentric cam 98 is pressed against the side surface portion 84a of the output side gear 84, so that the output side gear 84 reciprocates in the axial direction, and the cleaning member 81 is a support member. It is supported by the bearing hole 92b of 92 and reciprocates in the axial direction. Accordingly, the cleaning member 81 rotates N times while being in contact with the charging roller 71 and at the same time reciprocates in the axial direction.

  According to the embodiment, the charging device 40 includes the charging roller 71 that charges the photoreceptor 38, the cleaning member 81 that contacts the surface of the charging roller 71 and cleans the charging roller 71, and the cleaning member 81 is charged to the charging roller 71. And a drive mechanism unit 80 that is rotationally driven with a linear velocity difference and reciprocally driven along the axial direction. The drive mechanism 80 meshes with the worm 88 and a driving shaft member 85 having an input side gear 87 meshed with an output side gear 84 provided on the cleaning member 81 and a worm 88 provided coaxially with the input side gear 87. And a cam member 95 having an eccentric cam 98 that is pressed toward the axial direction of the cleaning member 81 and that displaces the cleaning member 81 in the axial direction by the rotation of the warm wheel 97.

  According to this configuration, when the driving shaft member 85 is driven to rotate, the cleaning member 81 is rotated by the rotation of the input side and output side gears 87 and 84, and the eccentric cam of the cam member 95 is engaged by the engagement of the worm 88 and the worm wheel 97. 98 decelerates and rotates, and according to the displacement of the eccentric cam 98, the cleaning member 81 reciprocates in the axial direction relatively slowly with respect to the rotation. Accordingly, since the cleaning member 81 rotates and slowly reciprocates in the axial direction, there is no risk of uneven rotation of the drive mechanism 80, and the photoconductor 38 rotates stably, and image defects such as band-shaped density unevenness occur. It is possible to satisfactorily remove the dirt adhering to the charging roller 71 without the occurrence of. Further, the drive mechanism unit 80 for driving the cleaning member 81 includes a driving shaft member 85 and a cam member 95. The number of constituent members is small, the configuration is simple, and the apparatus does not increase in size.

  According to the above embodiment, when the eccentric cam 98 is pressed against the side surface portion 84a of the output side gear 84 by the first spring member 75 and the eccentric cam 98 rotates, the cleaning member 81 reciprocates in the axial direction. Therefore, it is not necessary to provide a member such as a cam follower that presses against the eccentric cam 98, and the cleaning member 81 can be reliably reciprocated in the axial direction.

  Further, according to the above-described embodiment, the charging mechanism 40 does not become bulky because the drive mechanism 80 is rotatably supported on one end side in the case member 91 that supports the charging roller 71.

  Further, according to the above-described embodiment, the input side gear 87 meshes with the output side gear 84 provided on the cleaning member 81 and also meshes with the drum side gear 39 that is a drive source, so that the drive mechanism unit 80 is enlarged. There is no.

  In addition, according to the above embodiment, the case member 91 is made of resin, and the shaft portion 96 of the cam member 95 is rotatably fitted, and at least one of the long hole portion 91a and the long hole portion 91a is open at one end. A protruding portion 91d that protrudes from one inner side surface 91c and that a part of the outer peripheral surface of the shaft portion 96 abuts rotatably, and an inner side surface 91c that at least the protruding portion 91d is formed in the width direction of the long hole portion 91a. And a hole portion 91e formed at a predetermined interval.

  According to this configuration, when the shaft portion 96 of the cam member 95 is inserted into the elongated hole portion 91a of the case member 91 and then the shaft portion 96 is pushed into the protrusion portion 91d, the vicinity of the protrusion portion 91d is elastically deformed. The shaft portion 96 of the cam member 95 passes over the projection 91d and is rotatably supported by the fitting portion 91b and the projection 91d of the long hole portion 91a. Therefore, the cam member 95 can be easily attached to the case member 91, and the shaft portion 96 of the cam member 95 can be reliably supported on the case member 91.

  Further, according to the embodiment, the hole 91e of the case member 91 has an elongated shape along the long hole 91a, and at least the surface 91f on the side close to the protrusion 91d is on the open side of the long hole 91a. It is formed to be inclined so as to approach the long hole portion 91a as it goes.

  According to this configuration, the hole 91e of the case member 91 is formed to be inclined so as to approach the long hole 91a toward the open side of the long hole 91a, so that the open side near the hole 91e is elastically deformed. When the shaft portion 96 of the cam member 95 is pushed into the protruding portion 91d of the case member 91, the shaft portion 96 of the cam member 95 easily gets over the protruding portion 91d. For this reason, it can attach to the case member 91, without damaging the axial part 96 of the cam member 95, and can support the axial part 96 of the cam member 95 to the case member 91 reliably.

  In the above-described embodiment, the configuration in which the eccentric cam 98 abuts against the side surface portion 84a of the output side gear 84 when pressed is shown, but the present invention is not limited to this, and the eccentric cam 98 is pressed when pressed. 98 may contact the shaft member 83 of the cleaning member 81. In this case as well, the same effects as in the above embodiment can be obtained.

  INDUSTRIAL APPLICABILITY The present invention can be used for a charging device used in an image forming apparatus such as a copying machine, a printer, a facsimile, and a composite machine using the electrophotographic method, and an image forming apparatus including the charging device. The present invention can be used for a charging device having a cleaning mechanism and an image forming apparatus including the charging device.

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 38 Photoconductor (Image carrier)
39 Drum side gear 40 Charging device 71 Charging roller 74 Rotating shaft 75 First spring member (biasing member)
76 2nd spring member 80 Drive mechanism part 81 Cleaning member 83 Shaft member 84 Output side gear 84a Side face part 85 Driving shaft member 86 Shaft part 87 Input side gear 88 Warm 91 Case member 91a Long hole part 91b Fitting part 91c Inner side face 91d Projection 91e Hole 91f Inclined surface 92 Support member 92a Bearing 92b Bearing hole 92d Contact surface 95 Cam member 96 Shaft 97 Warm wheel 98 Eccentric cam 99 Cover member

Claims (7)

A charging roller that charges the image carrier, a cleaning member that contacts the surface of the charging roller to clean the charging roller, and the cleaning member is rotationally driven with respect to the charging roller with a linear velocity difference and is axially driven. In a charging device comprising a drive mechanism unit that reciprocates along,
The drive mechanism includes a driving shaft member having an input side gear meshing with an output side gear provided on the cleaning member, and a worm wheel coaxially provided with the input side gear, and a worm wheel meshing with the worm. A cam member having an eccentric cam that is pressed in the axial direction of the cleaning member and displaces the cleaning member in the axial direction by rotation of the worm wheel, and a biasing member that biases the cleaning member in the direction of the cam member And a charging device comprising:   The charging device according to claim 1, wherein the eccentric cam is pressed against a side surface portion of the input side gear by an urging force of the urging member.   The charging device according to claim 1, wherein the drive mechanism is rotatably supported at one end side in a case member that supports the charging roller.   The charging device according to claim 1, wherein the input-side gear meshes with a drum-side gear provided on the image carrier.   The case member is made of resin, and is formed so as to protrude from at least one inner surface of the long hole portion, and a long hole portion whose one end is opened while the shaft portion of the cam member is rotatably fitted. A hole formed at a predetermined interval between a protrusion with which a part of the outer peripheral surface of the member is rotatably contacted and at least an inner surface on which the protrusion is formed in the width direction of the elongated hole The charging device according to claim 3, further comprising:   The hole portion is an elongated shape along the long hole portion, and is formed so as to be inclined so that at least a surface close to the projection portion approaches the long hole portion toward the open side of the long hole portion. The charging device according to claim 5, wherein:   An image forming apparatus on which the charging device according to claim 1 is mounted.