JP4386069B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus including an electrophotographic image forming process unit, and more particularly to an improvement of a cleaning member in a corona discharger constituting the image forming process unit.

  An image forming apparatus including an electrophotographic image forming process unit is widely used in a copying machine, a facsimile machine, a printer, or a so-called multifunction machine having these functions. A corona discharger is incorporated as one component of such an image forming process unit. The corona discharger is a charger that uniformly charges the surface of the photosensitive drum, a transfer device that transfers the toner image on the surface of the photosensitive drum to a recording medium (recording paper), and further, a charge remover on the surface of the photosensitive drum. Used for static eliminators and the like Conventionally, a wire electrode has been used as an electrode of a corona discharger, but there is a problem of ozone generation, and recently, a needle electrode that generates less ozone has been frequently used.

The corona discharger using the needle electrode is suitable as a charger or the like constituting the image forming process unit as described above because it generates less ozone. However, foreign matter (toner, paper dust or Silicon or the like) easily adheres, and when this deposit increases, discharge unevenness may occur, which may cause image formation failure. Therefore, as shown in Patent Document 1, a corona discharger equipped with a cleaning device capable of appropriately wiping and cleaning the surface of the needle electrode has been put into practical use. The corona discharger cleaning device disclosed in Patent Document 1 sandwiches a needle electrode between a pair of rotatably supported rollers, and slides the pair of rollers along the longitudinal direction of the needle electrode in the sandwiched state. It is configured to be movable.
Japanese Patent No. 3259515

  By the way, in the cleaning device as disclosed in the above-mentioned Patent Document 1, the two shaft portions supporting the pair of rollers are urged in a direction facing each other, so that both rollers exert a urging load on both surfaces of the needle electrode. It will rotate in the state. Therefore, this load acts so as to prevent the rotation of both rollers, so that the sliding resistance is also increased. In order to relieve the load that hinders the rotation of the roller, the roller is supported on the support shaft via the bearing member, or the rotation shaft integral with the roller is supported by the bearing member, and the load is received by these bearing members. Although it is necessary to provide such a bearing member on both rollers, the number of parts increases.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus including a corona discharger that can be efficiently cleaned without increasing the number of parts.

The image forming apparatus of the present invention is an image forming apparatus provided with a corona discharger, wherein the corona discharger includes a needle electrode and a cleaning member that is slidable along the longitudinal direction of the needle electrode. The cleaning member includes a moving body attached to the case portion of the corona discharger so as to be reciprocally movable along the longitudinal direction of the needle electrode, and two cleaning members supported by the moving body and sandwiching the needle electrode from both sides. comprising a sliding member, and a biasing means provided between said moving body and said sliding member so as to elastically urged against one of the sliding member and the other sliding member, the moving body and The two slidable contact members are both made of an integrally molded resin body, and the one slidable contact member includes a slidable contact portion having a semicircular cross section, and the movable body can move to the other slidable contact member side. The non-rotating member is supported so as not to rotate. The needle electrode is supported between the non-rotating member and the curved surface portion of the rotating member in accordance with the movement of the moving body. It is characterized in that sliding contact cleaning is performed in a sandwiched state.

It can Te present invention smell, a charger for charging the surface of the photosensitive drum constituting the image forming process section pre Symbol corona discharger.

  In the image forming apparatus of the present invention, the corona discharger includes the needle electrode and a cleaning member that is slidable along the longitudinal direction across the needle electrode. The needle electrode is cleaned by sliding along the longitudinal direction. The cleaning member includes a moving body attached to the case portion of the corona discharger so as to be reciprocally movable along the longitudinal direction of the needle electrode, and two sliding members supported by the moving body and sandwiching the needle electrode from both sides, Since the slidable contact member is provided with an urging means provided between the movable body and the slidable contact member so as to elastically urge one slidable contact member with respect to the other slidable contact member, When the movable body is reciprocated between the members, the reciprocating movement is performed in a state where one slidable contact member is elastically biased with respect to the other slidable contact member by the urging means. Thus, wiping and cleaning of toner, silicon, and the like is effectively performed. Since the biasing load is applied to only one of the sliding contact members, the sliding resistance does not increase, and the bearing member receives the load in order to reduce the load. Does not need to be provided on both sliding contact members, and the number of parts is not increased.

The one slidable contact member is a non-rotating member supported by the movable body so as to be movable toward the other slidable contact member and non-rotatable. The other slidable contact member is used as a bearing portion of the movable body. because they consisted of pivotally supported shaft rotating member, a load is applied to a non-rotating member, not applied directly biasing load to the pivoting member, the pivoting member pivotally The supporting bearing portion does not need to be provided with a separate member so as not to hinder the rotation of the shaft rotating member, and is effective by reducing the number of parts.

  Further, when the corona discharger is a charger for charging the surface of the photosensitive drum constituting the image forming process section, a charger that easily adheres toner, paper dust, silicon, etc. to the needle electrode. The suitability as a cleaning device is further increased.

  The best mode for carrying out the present invention will be described below with reference to the drawings. 1 is a schematic longitudinal sectional view showing an image forming apparatus according to an embodiment of the present invention, FIG. 2 is a longitudinal sectional view of a drum unit in the image forming apparatus, and FIG. 3 is a perspective view of a charger incorporated in the image forming apparatus. 4 is a partially broken perspective view seen from the direction of the arrow X in FIG. 3, FIG. 5 is an exploded perspective view of the cleaning member attached to the charger, and FIG. 6 is a cross-sectional view taken along the line YY in FIG. 7 and 7 are cross-sectional views taken along the line ZZ in FIG.

The image forming apparatus A shown in FIG. 1 is illustrated by taking a printer having an electrophotographic recording unit as an example. However, the image forming apparatus A is not limited to this, and is not limited to this. A so-called multifunction machine or the like may also be used. In the figure, the apparatus main body 1 of the image forming apparatus A includes a recording paper (paper) feeding unit 2, an electrophotographic image recording unit 3, and a printed recording paper discharging unit 4 in this order. Layered in the height direction. The recording paper feeding unit 2 includes a detachable paper feeding cassette 2a capable of accumulating and storing a large number of recording papers, a separation paper feeding roller 2b installed at the front end in the paper feeding direction of the paper feeding cassette 2a, The separation pad 2c is elastically contacted with the peripheral surface of the separation sheet feeding roller 2b.
It should be noted that a similar cassette can be stacked under the paper feed cassette 2a to form a multi-stage cassette, or an optional cassette (not shown) can be installed. Further, a retard roller may be used instead of the separation pad 2c.

  The image recording unit 3 includes a corona charging type charger (corona discharger) 6, an exposure unit 7 including an LED, a developing unit 8, a transfer roller (transfer unit) 9, and a transfer residual toner around the photosensitive drum 5. The cleaning unit 10 is arranged in this order, and a fixing unit 11 on the downstream side thereof. These process units, except for the exposure device 7 and the transfer roller 9, are a drum unit 50 in which the photosensitive drum 5, the charger 6 and the cleaning device 10 are integrated, a developing device housing 81, stirring and conveying screws 82 and 83, a supply paddle 84, The developing unit 80 is a process unit including the developing roller 85 and the like.

  The developing unit 80 shown in the figure is a developing unit using a two-component developer, and stores toner and a carrier in a developing device housing 81 that also serves as a resin-molded developer container. The developer is supplied to the developing roller 85 biased by the supply paddle 84 while being stirred and transported by the stirring and transporting screws 82 and 83. A magnetic sensor 86 is attached to the outer surface of the developing device housing 81 to detect the toner density (mixing ratio of toner and carrier) in the developing device housing 81. A toner tank 12 and a toner hopper 13 as a toner storage unit are installed at a position apart from the developing unit 80, and when the magnetic sensor 86 detects that the toner concentration in the developing unit housing 81 has decreased. The toner is replenished from the toner hopper 13 into the developing device housing 81 via a screw conveyor (pipe screw) 14. A toner agitator 15 and a toner conveying / discharging screw 16 to the toner hopper 13 are disposed in the toner tank 12, and the toner tank 12 having the toner agitating agitator 15 and the toner conveying / discharging screw 16 is provided. Is configured as a toner cartridge 18 which is integrated with a waste toner tank 17 which will be described later, and is detachably attached to the apparatus main body 1.

  The drum unit 50 and the developing device unit 80 are detachably attached to the apparatus main body 1 from the front side thereof individually or in a state where both are connected by some connecting means. It is also possible to make all the process parts except the exposure device 7 and the transfer roller 9 collectively a process unit. Further, the toner cartridge 18 is also detachably attached to the apparatus main body 1 from the front side. These process units 50 and 80 and the toner cartridge 18 are appropriately replaced with new ones as consumables. Here, the front side of the apparatus main body 1 refers to the front side of the sheet in FIG. 1, and the paper feed cassette 2 a is also removable from the front side of the apparatus main body 1.

  Connected to the waste toner tank 17 constituting the toner cartridge 18 is a screw conveyor 19 for sequentially transporting and feeding the waste toner removed and collected by the cleaning device 10. The waste toner discharged / injected from the waste toner discharge port is dispersed and accumulated in the waste toner tank 17 by the conveying screw 17 a disposed in the waste toner tank 17.

  On the downstream side of the fixing device 11, a switching gate 4a, a discharge roller pair 4b, and a discharge tray 4c are connected in series, and the discharge unit 4 is configured by these. A registration roller pair 20 is disposed in the vicinity of the upstream side of the process section, and the recording paper (paper) separated and fed out from the paper feed cassette 2a one by one by the action of the separation paper feed roller 2b and the separation pad 2c. Is registered by the registration roller pair 20 and introduced into the mating portion between the photosensitive drum 5 and the transfer roller 9. The surface of the photosensitive drum 5 is negatively charged by the charger 6 while rotating in the direction of the arrow in FIG. 1, and an optical image based on the image information is irradiated to the surface of the photosensitive drum 5 by the exposure device 7. An electrostatic latent image is formed on the surface of the photosensitive drum 5. This electrostatic latent image is formed by changing the potential of the light irradiated portion and maintaining the potential of other portions depending on the characteristics of the photoconductor on the surface of the photosensitive drum 5.

  The electrostatic latent image is successively developed by a developing device 8 to which a bias is applied, and reaches a matching portion between the photosensitive drum 5 and the transfer roller 9 as a toner image. During this development, toner is attracted to the photosensitive drum 5 due to a potential difference with the developing unit 8 at a portion where the potential has changed due to light irradiation, so that a black portion is formed. As a result, a black and white toner image based on the image information is formed. The registration roller pair 20 is rotationally driven under registration control so that the recording paper is introduced into the mating portion in synchronization with the toner image on the surface of the photosensitive drum 5.

  A bias is applied to the transfer roller 9, and the recording paper is nip-conveyed while being paired with the photosensitive drum 5 and being rotationally driven in the direction indicated by the arrow (with respect to the photosensitive drum 5). The toner image is transferred onto the recording paper. Toner remaining on the surface of the photosensitive drum 5 (which may include paper dust) is removed and collected by the cleaning device 10. The recording paper onto which the toner image has been transferred is introduced into the fixing device 11 and fixed as a permanent image, and then the switching gate 4a is pushed up and discharged onto the discharge tray 4c through the discharge roller pair 4b. This series of recording paper feeds rises substantially vertically (vertically) immediately after feeding from the paper feed cassette 2a, and the discharge roller pair 4b makes a U-turn in a direction of about 180 degrees from the feed direction from the paper feed cassette 2a. This is done along the main feeding path P. With such a layout configuration, the entire apparatus can be made compact.

  The image forming apparatus A shown in the figure has a double-sided recording function, and circulates and joins the main feeding path P upstream of the registration roller pair 20 from the mounting position of the switching gate 4a of the main feeding path P. A reverse feeding path P1 is formed. The discharge roller pair 4b can be rotated forward and backward, and the reverse feeding path P1 is provided with a pair of conveying rollers 21 and 22. When performing double-sided recording, single-sided recording was performed as described above. When the recording paper is conveyed along the main feed path P and the trailing edge of the recording paper reaches the discharge roller pair 4b, the discharge roller pair 4b temporarily stops and nips the trailing edge of the recording paper. Next, the discharge roller pair 4 b is reversed, and the recording paper is conveyed from the rear end thereof by the conveying roller pairs 21 and 22 through the reverse feeding path P 1, joined to the main feeding path P, and reaches the registration roller pair 20. It is registered by the registration roller pair 20 and is again introduced into the mating portion between the photosensitive drum 5 and the transfer roller 9 to record the back surface thereof. The recording paper recorded on both sides is then discharged onto the discharge tray 4c along the main feeding path P as described above.

  The image forming apparatus A shown in the figure is further provided with a manual sheet feeding function, and a manual sheet feeding tray 23 that can be opened and closed in a three-stage sliding manner is attached to the side of the apparatus body 1. Yes. When not in use, the manual paper feed tray 23 is closed in a contracted state as indicated by a two-dot chain line in FIG. 1. When in use, the manual paper feed tray 23 is opened by opening the handle 23a and placed for paper feeding. The expansion is appropriately performed according to the size of the recording paper. A manual feed roller 23b and a separation pad 23c are arranged in a resilient contact state at the front end of the manual feed tray 23, and a manual feed path that joins the main feed path P further downstream. P2 is continuously provided.

  The toner hopper 13 is for temporarily storing the toner supplied from the toner tank 12. When the magnetic sensor 86 of the developing device 8 sends out a toner-free signal, the screw conveyor connected to the toner hopper 13 is used. 14 operates to supply toner into the developer housing 81. The operation of the toner conveying / discharging screw 16 is controlled by a detection signal of a sensor (not shown) installed in the toner hopper 13 so that a predetermined amount of toner is always stored in the toner hopper 13. . The predetermined amount of toner stored in the toner hopper 13 is set to an amount sufficient to continue the printing operation until the toner in the toner tank 12 runs out and is replaced with a new toner cartridge 18, for example. The

  Next, the photosensitive drum unit 50 integrally including the charger 6 will be described in detail with reference to FIG. The photosensitive drum 5 is formed by coating a photoconductive body on the surface of a conductive cylindrical body such as aluminum, and flange members 5a and 5b made of an insulating resin or the like are fixed to openings at both ends. The photosensitive drum 5 has a single shaft (drum shaft) 51c coaxially inserted through the flange members 5a and 5b at both ends, and can rotate about a unit frame 51 made of a resin molded product via the bearings 51a and 51b. It is supported by. Gears 5c and 5d are concentrically formed on the peripheral surfaces of the flange members 5a and 5b. The gear 5c is meshed with a drive transmission system (not shown) in the apparatus main body 1 and obtains this driving force to be photosensitive. The body drum 5 rotates about the drum shaft 51c. The opposite gear 5d meshes with a driven transmission gear (not shown) of a mechanism portion such as the transfer roller 9, and rotational drive transmission to these mechanism portions is performed.

  The charger 6 is a scorotron type corona discharger, and includes a pair of attachment members 61 and 62 that are attached and fixed to both ends of the unit frame 51, and a needle electrode 63 that is stretched between the attachment members 61 and 62. A shield case (case part) 64 having a U-shaped cross section that is coupled and supported between the mounting members 61 and 62 and covers the needle electrode 63, and a photosensitive drum side of the shield case 64 that is stretched between the mounting members 61 and 62. The grid 65 arranged in the opening is configured as a unit. The attachment members 61 and 62 are fastened and fixed to the unit frame 51 by screws 61b and 62b through screw holes 61a and 62a formed respectively.

  The needle electrode 63 is a corona discharge electrode, and is formed of a strip metal plate having a large number of needle-like electrodes 63a as shown in the figure. One end 63b of the needle electrode 63 is hooked in one mounting member 61, and the other end 63c is hooked in the other mounting member 62 via a tension spring 63d. It is stretched with tension applied. The grid 65 is made of a thin metal plate having a large number of slits. One end 65a of the grid 65 is hooked to one attachment member 61, and the other end 65b is attached to the other via a swinging piece 65c and a tension spring 65d. It is hooked on the member 62.

  The swinging piece 65c is disposed on the mounting member 62 so as to penetrate from the photosensitive drum 5 side to the opposite side, and is supported so as to be swingable with the fulcrum pin 65ca as a fulcrum. The other end 65b of the grid 65 is hooked to the projecting end of the swinging piece 65c on the photosensitive drum 5 side, and a tension spring 65d is hooked to the opposite projecting end. The needle electrode 63 and the grid 65 are joined to a power supply electrode (not shown) in the apparatus body 1 when the photosensitive drum unit 50 is mounted at a predetermined position of the image forming apparatus A, and a predetermined voltage is applied to each. It is made to be done. Further, the mounting members 61 and 62 and the shield case 64 are integrally coupled.

  The charger 6 includes a cleaning member 24 that sandwiches the needle electrode 63 and is slidable along the longitudinal direction thereof. As shown in FIGS. 2 to 7, the cleaning member 24 includes a moving body 25 attached to the shield case 64 so as to be reciprocally movable along the longitudinal direction of the needle electrode 63, and a needle supported by the moving body 25. Two sliding contact members 30 and 31 sandwiching the electrode 63 from both sides, and between the movable body 25 and the sliding contact member 30 so as to elastically bias one sliding contact member 30 against the other sliding contact member 31. And an urging means 32 provided in the apparatus. The movable body 25 has a U-shaped movable body main body 26 that holds two sliding contact members 30 and 31, and a pressing member 27 that presses the sliding contact members 30 and 31 supported by the movable body main body 26 so as not to be detached. And an attaching part piece 28 for fixing the moving body 25 to the tip of the operation rod 29, which is fixed to the back part of the moving body 26 with a screw 28a. The fixing and integration of the moving body 26 and the attachment piece 28 with the screw 28a is performed by penetrating through the opening 64a formed in the longitudinal direction on the back portion of the U-shaped shield case 64 and straddling the width direction of the opening periphery. With the movable body main body 26 and the attachment piece 28 being integrated, the opening 64a can be moved along the longitudinal direction of the shield case 64 (needle electrode 63).

  Both legs of the movable body 26 can be elastically deformed, and locking claws 26a and 26b are formed at the ends thereof. The locking claws 26a and 26b are inserted and locked to the pressing member 27 via locking holes 27a and 27b formed in the pressing member 27, whereby the pressing member 27 is later described with respect to the movable body 26. Thus, the two sliding contact members 30 and 31 held at predetermined positions are mounted so as not to be detached.

  The one slidable contact member 30 is a non-rotating member supported by the movable body 26 so as to be movable toward the other slidable contact member 31 and non-rotatable. More specifically, the non-rotating slidable contact member 30 includes a slidable contact portion 30a having a semicircular cross section, and a base 30b having a concave cross section formed integrally on the back side of the slidable contact portion 30a along the longitudinal direction. And locking pins 30c and 30d formed at both ends in the longitudinal direction. When the sliding contact member 30 is mounted and held on the movable body 25, the locking pins 30 c and 30 d at both ends are inserted into the long holes 26 c and 27 c formed in the movable body main body 26 and the pressing member 27. The longitudinal direction of the long holes 26c and 27c is directed in the opposing direction of the two sliding contact members 30 and 31, whereby the sliding contact member 30 is in this opposing direction (see the direction of arrow a in FIG. 6) in the mounted state. It is possible to move along.

  Further, the base 30b is engaged in the recess so as to surround the base of the locking claw 27a and the elastic part 26d formed in a cantilever shape on the one leg side of the movable body 26, and has an oval shape. In addition to the engagement relationship between the locking pin 30d and the long hole 26c, the sliding contact member 30 is not rotatable in the mounted state. A protrusion 30e is formed on the inner surface of the concave portion of the base portion 30b. In the mounted and held state, the protrusion 30e abuts against the elastic portion piece 26d so that the elastic portion piece 26d is located at the position of the solid line from the two-dot chain line in FIGS. To be elastically deformed. The elastic piece 26d functions to elastically urge the sliding contact member 30 toward the other sliding contact member 31 by its restoring elasticity, and thereby the urging means 32 is configured.

  The other slidable contact member 31 includes a roller member 31a having a circular cross section and rotation support shafts 31b and 31c formed coaxially at both ends in the longitudinal direction. A shaft hole 26e and a shaft hole 27d as a bearing portion are formed in the moving body main body 26 and the pressing member 27. The sliding contact member 31 has the rotation support shafts 31b and 31c in the above-described mounting and holding state with respect to the moving body 25. The sliding contact member 31 is pivotally supported by the shaft hole 26e and the shaft hole 27d, and is a shaft rotation member that can rotate around the axis of the rotation support shafts 31b and 31c. The two sliding members 30 and 31 are mounted and held by the movable body 26 and the pressing member 27 so as to sandwich the needle electrode 63 of the charger 6 from both sides, and are attached to the tip of the operation rod 29. The cleaning member 24 that is attached to the shield case 64 via the piece 28 and is slidable along the longitudinal direction of the needle electrode 63 is configured. Each of the two sliding members 30, 31 and the movable body 25 is preferably made of an integrally molded resin.

  A procedure for cleaning the needle electrode 63 in the charger 6 including the cleaning member 24 configured as described above will be described. As shown in FIGS. 2 and 3, an operation knob 29a is formed on the base side of the operation rod 29 (on the side of the maintenance door (not shown) provided on the apparatus main body 1). Open, hold the operation knob 29a, and repeat the pulling operation. By this pulling operation, the cleaning member 24 repeats reciprocation along the longitudinal direction of the needle electrode 63 as indicated by an arrow b in FIG. During this reciprocating movement, the needle electrode 63 is sandwiched between the two sliding members 30 and 31, so that the toner, paper powder, or silicon adhering to the needle member 63 by the sliding action of the sliding members 30 and 31. Etc. are wiped away. Then, the biasing force in the direction of arrow a is applied to the sliding contact member 30 by the action of the biasing means 32, whereby the two sliding contact members 30 and 31 elastically sandwich the needle electrode 63. Is made effective.

  When reciprocating in the state of being elastically biased in this way, the sliding contact member 31 made of a shaft rotating member is driven by the relative movement of the needle electrode 63 to rotate axially as indicated by an arrow c in FIG. Thereby, the smooth reciprocation of the cleaning member 24 is made. Since this sliding contact member 31 does not receive a direct elastic biasing load, its rotation does not hinder its rotation. The slidable contact member 30 made of a non-rotating member is elastically slid to the needle electrode 63 while the semicircular slidable contact portion 30 a is elastically biased toward the slidable contact member 31. Since the curved surface portion of the sliding contact portion 30a is a sliding contact surface with the needle electrode 63, this elastic sliding is also reduced in resistance. Such a function of the cleaning member 24 is achieved without using a bearing member or the like for receiving a load, and is effective in reducing the number of parts.

  In the above embodiment, an example in which the corona discharger is a charger has been described. However, the present invention can also be applied to other corona dischargers provided around the transfer unit and the photosensitive drum as necessary. Further, as the urging means 32, a plate spring or other elastic urging member may be employed in addition to the urging member 32d and the projection 30e as shown in the figure. Furthermore, although the example in which the process units 50 and 80 and the toner cartridge 18 are mounted from the front side of the apparatus main body 1 has been described, the present invention can also be applied to the case where the process units 50 and 80 and the toner cartridge 18 are mounted from the left and right side surfaces or the back side. . Furthermore, although a system using a two-component developer has been exemplified as the developing device 8, the present invention is not limited to this and can be applied to a single-component development system.

1 is a schematic longitudinal sectional view showing an image forming apparatus according to an embodiment of the present invention. 2 is a longitudinal sectional view of a drum unit in the image forming apparatus. FIG. FIG. 3 is a perspective view of a charger incorporated in the image forming apparatus. FIG. 4 is a partially broken perspective view seen from the arrow X-ray direction in FIG. 3. It is a disassembled perspective view of the cleaning member with which the charger is attached. FIG. 6 is a cross-sectional view taken along line YY in FIG. 4. FIG. 7 is a sectional view taken along line ZZ in FIG. 6.

Explanation of symbols

1 Image forming apparatus body 6 Charger (corona discharger)
63 Needle electrode 64 Shield case (case part)
24 Cleaning member 25 Moving body 26e Shaft hole (bearing part)
27d Shaft hole (bearing part)
30 Sliding member (non-rotating member)
31 Sliding member (shaft rotating member)
32 Biasing means A Image forming apparatus

Claims (2)

An image forming apparatus provided with a corona discharger,
The corona discharger includes a needle electrode and a cleaning member that is slidable along the longitudinal direction with the needle electrode interposed therebetween,
The cleaning member includes a moving body attached to the case portion of the corona discharger so as to be reciprocally movable along the longitudinal direction of the needle electrode, and two sliding members supported by the moving body and sandwiching the needle electrode from both sides. Urging means provided between the movable body and the sliding contact member so as to elastically bias one sliding contact member with respect to the other sliding contact member,
The movable body and the two sliding contact members are both made of an integrally molded body of resin,
The one sliding contact member includes a non-rotating member that includes a sliding contact portion having a semicircular cross section, is supported on the movable body so as to be movable toward the other sliding contact member, and is non-rotatable. Includes a roller member having a circular cross section, and is composed of a shaft rotating member that is supported by the bearing portion of the moving body so that the shaft can rotate.
An image forming apparatus, wherein the needle electrode is slidably cleaned while being sandwiched between curved surfaces of the non-rotating member and the rotating member in accordance with the movement of the moving body. The image forming apparatus according to claim 1.
An image forming apparatus, further comprising a photosensitive drum, wherein the corona discharger is a charger for charging the surface of the photosensitive drum.

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