JP6638596B2 - Charging device and image forming device - Google Patents

Description

  The present invention relates to a charging device that charges an image carrier by corona discharge using a discharge wire, and an image forming apparatus including the charging device.

  Conventionally, electrophotographic image forming apparatuses such as copiers and printers include an image carrier such as a photosensitive drum on which an electrostatic latent image is formed in accordance with image data, a charging device that charges the surface of the image carrier, A static eliminator such as a static elimination lamp for eliminating unnecessary charges of the image carrier is provided. As the charging device, there is a corotron-type charging device that includes a shield case and a discharge wire that is stretched inside the shield case and generates a corona discharge, and is arranged in non-contact with the image carrier.

  The charging device has an opening in the surface of the shield case on the image carrier side in order to charge the image carrier with the charge generated by corona discharge of the discharge wire. When discharge products such as ozone generated by corona discharge stay around the discharge wires, the discharge wires are contaminated, causing poor charging and further causing image defects. Therefore, it is necessary to avoid the stay of the discharge products. is there.

  For example, the image forming unit of Patent Document 1 has a corotron including a discharge wire for charging a photosensitive drum to a predetermined potential, and a shield member surrounding the discharge wire and having an opening on the photosensitive drum side. This image forming unit circulates the discharge product generated from the corotron from the side of the upstream shield member toward the back of the corotron opposite to the photosensitive drum against the flow of air near the corotron. An elastic seal member for preventing the vibration is provided. This prevents circulation of the discharge products generated from the corotron, and discharges the discharge products outside the device.

JP 2006-91327 A

  The charging device such as the above-mentioned corotron has openings on the surface of the shield case opposite to the image carrier, and blows through these openings using a blower such as a fan to discharge electric discharge products. Avoid stagnation. However, since the static eliminator is provided near the image carrier, if an opening is provided on the surface of the shield case opposite to the image carrier, the static elimination light and the reflected light are shielded through this opening. There is a possibility that the toner enters the case and the charged potential (surface potential of the image carrier) decreases.

  SUMMARY OF THE INVENTION It is an object of the present invention to avoid stagnation of discharge products and to prevent a reduction in charging potential due to static elimination light and its reflected light.

  A charging device according to the present invention includes a shield case having a first opening provided on a facing surface facing an image carrier and a second opening provided on an end surface opposite to the facing surface; A discharge wire that is provided along the shield case along the side close to the opposing surface, and that is spaced apart from each other in the longitudinal direction of the shield case. And a plurality of shielding plates standing upright on the end face.

  According to such a configuration, in the charging device, the plurality of shielding plates prevent the static elimination light from the static eliminator near the charging device and the reflected light from entering the shield case through the second opening. Therefore, a decrease in the charging potential of the charging device can be avoided. Furthermore, in the charging device, the air from the blower fan or the like is guided to the shield case through the second opening by the plurality of shield plates, so that the air can be sent into the shield case, and the discharge around the discharge wire can be performed. The stagnation of discharge products can be avoided.

  The charging device is provided at one end in the longitudinal direction of the shield case, and cleans the discharge wire while reciprocating between the one end and the other end in the longitudinal direction of the shield case along the end surface. It is preferable that the shielding member further includes a cleaning member, and the plurality of shielding plates are configured in a blind shape that can expand and contract in a longitudinal direction of the shield case in accordance with reciprocation of the cleaning member.

  By employing such a configuration, a plurality of shielding plates can be provided without obstructing cleaning of the discharge wire by the cleaning member.

  The charging device described above may further include an angle adjusting mechanism capable of adjusting the standing angle of the plurality of shielding plates with respect to the end surface.

  By adopting such a configuration, it is possible to adjust the standing angle of the plurality of shielding plates to avoid the penetration of the static elimination light or the like into the shield case and optimize the ventilation into the shield case. it can. Further, it is also possible to adjust the standing angles of the plurality of shielding plates according to the configuration and specifications of the image forming apparatus and the charging device.

  The angle adjusting mechanism adjusts the standing angle of the plurality of shielding plates to be small so as to cover the second opening during the printing operation of the image carrier, and the second angle during the non-printing operation of the image carrier. It is preferable that the standing angles of the plurality of shielding plates be adjusted so as to open the opening.

  By adopting such a configuration, at the time of a printing operation in which static elimination light is generated by the static eliminator, the second opening is covered with a plurality of shielding plates, thereby more reliably preventing static elimination light and the like from entering the shield case. can do. Also, during a non-printing operation in which static elimination light is not generated, by opening the second opening, more air can be sent into the shield case, and the stagnation of the discharge product around the discharge wire can be more reliably achieved. Can be avoided.

  An image forming apparatus according to the present invention includes any one of the charging devices described above.

  ADVANTAGE OF THE INVENTION According to this invention, while staying of a discharge product can be avoided, it becomes possible to avoid the fall of charge potential by static elimination light or its reflected light.

FIG. 1 is a cross-sectional view schematically illustrating a printer according to an embodiment of the invention. FIG. 2 is a cross-sectional view illustrating a charging device and its periphery in an image forming unit of the printer according to the embodiment of the present disclosure. FIG. 1 is a perspective view showing a charging device of a printer according to an embodiment of the present invention. FIG. 3 is a cross-sectional view illustrating a charging device in a state where a plurality of extended shield plates are erected at a large angle in the printer according to the embodiment of the present invention. FIG. 3 is a cross-sectional view illustrating the charging device in a state where a plurality of extended shield plates are erected at a small angle in the printer according to the embodiment of the present invention. FIG. 3 is a cross-sectional view illustrating the charging device in a state in which a plurality of shielding plates are shortened in the printer according to the embodiment of the present disclosure.

  First, the overall configuration of the printer 1 (image forming apparatus) will be described with reference to FIG. Hereinafter, for convenience of explanation, the front side of the paper in FIG. 1 is referred to as the front side (front side) of the printer 1.

  The printer 1 includes a box-shaped printer main body 2. A paper feed cassette 3 for storing paper is accommodated in a lower portion of the printer main body 2, and a paper discharge tray 4 is provided on an upper surface of the printer main body 2.

  An exposing unit 5 composed of a laser scanning unit (LSU) is arranged below the discharge tray 4 on the upper part of the printer main body 2, and an image forming unit 6 is provided below the exposing unit 7. The image forming unit 6 is provided with a photosensitive drum 10 serving as an image carrier so as to be rotatable, that is, the image forming unit 6 is configured as a drum unit. Further, the image forming section 6 includes a charging device 11, a developing device 12, a transfer roller 13, a cleaning device 14, and a static eliminator 15 in the rotation direction of the photosensitive drum 10 around the photosensitive drum 10. (See arrow X in FIG. 1). The static eliminator 15 is configured by a static elimination lamp or the like. The static eliminator 15 emits the static elimination light L to the surface of the photosensitive drum 10 downstream of the cleaning device 14 and upstream of the charging device 11 in the rotation direction of the photosensitive drum 10. Irradiate (see FIG. 2).

  A paper transport path 16 is provided inside the printer body 2. A paper feed unit is provided at the upstream end of the transport path 16. A transfer unit 17 including the photosensitive drum 10 and the transfer roller 13 is provided at a middle part of the transport path 16. A fixing device is provided at a downstream portion of the transport path 16, and a paper discharge section is provided at a downstream end of the transport path 16. A reversing path for duplex printing is formed below the transport path 16.

  Next, an image forming operation of the printer 1 having such a configuration will be described. When image data is input from an external computer or the like and an instruction to start printing is given, the printer 1 starts an image forming operation. First, after the surface of the photosensitive drum 10 is charged by the charging device 11, exposure corresponding to image data is performed on the photosensitive drum 10 by a laser beam (see a two-dot chain line P in FIG. 1) from the exposure device 5. Then, an electrostatic latent image is formed on the surface of the photosensitive drum 10. Next, the developing device 12 develops the electrostatic latent image into a toner image with toner.

  On the other hand, the paper stored in the paper feed cassette 3 is taken out by the paper feed unit and transported on the transport path 16. The sheet is conveyed to the transfer unit 17 at a predetermined timing, and the transfer unit 17 transfers the toner image on the photosensitive drum 10 to the sheet. The sheet on which the toner image has been transferred is transported to a fixing device, and the toner image is fixed on the sheet by the fixing device. The sheet on which the toner image has been fixed is discharged to the sheet discharge tray 4 from the sheet discharge section. The toner and the charge remaining on the photoconductor drum 11 are removed by the cleaning device 14 and the static eliminator 15.

  Next, the charging device 11 will be described. As shown in FIGS. 1 and 2, the charging device 11 is provided above the photosensitive drum 10 in the image forming unit 6. In the image forming section 6, the static eliminator 15 on the upstream side of the charging device 11 is provided near (for example, above) the charging device 11. The charging device 11 includes a shield case 20, a discharge wire 21, a cleaning member 22, a plurality of shielding plates 23, and a blower fan 24, as shown in FIGS. Hereinafter, an example of the charging device 11 provided above the photoconductor drum 10 will be described. However, the charging device 11 may be configured such that the opposing surface 20 a of the shield case 20 is opposed to the peripheral surface of the photoconductor drum 10. It may be provided at any position with respect to the drum 10.

  The shield case 20 is formed in a substantially box shape that is long in the axial direction (the front-back direction) of the photoconductor drum 10. The shield case 20 has a lower surface 20a facing the peripheral surface of the photoconductor drum 10, and a first opening 20b is formed in the lower surface 20a. The first opening 20b is formed, for example, longer than the image forming area of the photosensitive drum 10 in the front-rear direction. The shield case 20 has an upper end face 20c opposite to the opposing face 20a, and a second opening 20d is formed in the end face 20c. For example, the second opening 20d is formed to be longer than the image forming area of the photosensitive drum 10 in the front-rear direction, and may have the same length as the first opening 20b. Note that the second opening 20d may be formed to have a smaller width than the first opening 20b in the sheet conveyance direction (left-right direction).

  As shown in FIG. 3, a front protection member 25 and a rear protection member 26 are provided at both ends in the front-rear direction of the shield case 20, respectively. The front protection member 25 and the rear protection member 26 protect both ends of the shield case 20 in the front-rear direction and both ends of the discharge wire 21 in the front-rear direction, and are used for mounting a plurality of shielding plates 23. Rails 27 used for moving the cleaning member 22 are formed on both side surfaces of the shield case 20 in the left-right direction. Also, inside the shield case 20, as shown in FIG. 4 and the like, support members 28 for supporting both ends in the front-rear direction of the discharge wire 21 are provided at both ends in the front-rear direction, and adjustment members 29 for adjusting the tension of the discharge wire 21 are provided. Is provided at any one end in the front-rear direction.

  One end of the discharge wire 21 is connected to a high-voltage power supply (not shown), and generates a corona discharge by applying a predetermined voltage (several tens of KV). The discharge wire 21 is provided in the shield case 20 along the longitudinal direction of the shield case 20. The discharge wire 21 is stretched by supporting both ends of the discharge wire 21 by support members 28 at both ends in the front-rear direction in the shield case 20, and the tension of the discharge wire 21 is adjusted by an adjusting member 29 in the shield case 20. . For example, the discharge wire 21 extends along the axial direction of the photoconductor drum 10 on the side (lower side) of the shield case 20 close to the surface 20 a facing the photoconductor drum 10, for example, the image of the photoconductor drum 10. It is stretched over a longer distance than the formation area.

  The cleaning member 22 is mounted movably in the front-rear direction above the shield case 20, and is locked at the rear end position of the shield case 20 in a standby state, and is unlocked in a cleaning state. The cleaning member 22 includes, for example, a cleaning case 30 that is hollow and has an open lower side, and a wire cleaning unit 31 that is provided in the cleaning case 30 and cleans the discharge wires 21.

  The cleaning case 30 engages with the rail 27 of the shield case 20 on both inner side surfaces, and the cleaning member 22 moves in the front-rear direction along the rail 27. Although the cleaning member 22 is configured to move manually, a mechanism that automatically moves may be provided. When the cleaning member 22 moves from the rear end side of the shield case 20 to the front end side, a plurality of shielding plates 23 are sequentially collected inside or on the front side of the cleaning case 30 (see FIG. 6). Further, when the cleaning member 22 moves from the front end side to the rear end side of the shield case 20, the plurality of shielding plates 23 are sequentially released from the cleaning case 30. The wire cleaning unit 31 is disposed in the cleaning case 30 corresponding to the discharge wire 21, and the wire cleaning unit 31 moves in the front and rear direction along the discharge wire 21 by moving the cleaning member 22 in the front and rear direction. The discharge wire 21 is cleaned.

  Each shielding plate 23 is formed in a thin plate shape having a rectangular plane in black, and is formed of, for example, a plastic material. The plurality of shielding plates 23 are stacked so that their respective planes are parallel to each other, are arranged at intervals in the longitudinal direction of the shield case 20, and are disposed on the end surface 20c of the shield case 20 on the second opening 20d side. It is erected for it. Therefore, the plane of each shielding plate 23 faces the axial direction of the photosensitive drum 10.

  In addition, the plurality of shielding plates 23 are configured in a blind shape that can expand and contract in the longitudinal direction of the shield case 20 according to the reciprocating movement of the cleaning member 22. In other words, the plurality of shield plates 23 are attached to the shield case 20 so as to be able to expand and contract in the longitudinal direction of the shield case 20 according to the reciprocating movement of the cleaning member 22 while maintaining the standing angle with respect to the end surface 20c of the shield case 20. Can be In a normal state (see FIG. 4), the plurality of shielding plates 23 are arranged to be inclined forward at a 45 ° standing angle with respect to the end surface 20c on the side of the second opening 20d. This prevents the static elimination light from the static eliminator 15 and its reflected light from entering the shield case 20 through the second opening 20d, and reduces the air flow from the blower fan 24 through the second opening 20d. 20 can be supplied.

  For example, the attachment mechanism 32 for the plurality of shielding plates 23 includes a positioning cord 33, an angle adjusting mechanism 34, a telescopic cord 35, and a winding mechanism 36.

  The positioning cord 33 is sequentially connected to each shielding plate 23, and is installed between the front protection member 25 of the shield case 20 and the cleaning member 22. Thereby, in a state where the cleaning member 22 is located on the rear end side of the shield case 20 and the stretchable cord 35 is extended (see FIG. 4), the positioning cord 33 is tensioned in the front-rear direction, and 23, the distance between the frontmost shielding plate 23 and the front protection member 25, and the distance between the rearmost shielding plate 23 and the cleaning member 22 are maintained. On the other hand, when the cleaning member 22 moves from the rear end side to the front end side of the shield case 20 and the stretchable cord 35 is shortened (see FIG. 6), the positioning cord 33 is released and relaxed. .

  The positioning cord 33 is connected to, for example, the upper left cord 33a connected to the upper left of each shielding plate 23, the lower left cord 33b connected to the lower left of each shielding plate 23, and the upper right part of each shielding plate 23. And a lower right string 33d connected to the lower right of each shielding plate 23. The front ends of the upper left cord 33a, the lower left cord 33b, the upper right cord 33c, and the lower right cord 33d are attached to the drive cam 37 of the angle adjusting mechanism 34 in the front protection member 25, and the upper left cord 33a, the lower left cord 33b, the upper right cord 33c, The rear end of the lower right cord 33d is attached to a driven cam 38 in the cleaning member 22. The driven cam 38 is formed in an elliptical shape and is rotatably provided in the cleaning member 22. For example, the rear ends of the upper left cord 33a and the upper right cord 33c are attached to one end (upper end) in the long axis direction of the driven cam 38, and the rear ends of the lower left cord 33b and the lower right cord 33d are arranged in the long axis direction of the driven cam 38. Attached to the other end (lower end).

  The angle adjusting mechanism 34 includes, for example, a drive cam 37 to which the front ends of the upper left cord 33a, the lower left cord 33b, the upper right cord 33c, and the lower right cord 33d of the positioning cord 33 are attached, and a drive such as a motor for rotating the drive cam 37. (Not shown). For example, the front ends of the upper left string 33a and the upper right string 33c are attached to one end (upper end) of the drive cam 37 in the long axis direction, and the front ends of the lower left string 33b and the lower right string 33d are the other ends in the long axis direction of the drive cam 37. Attached to the end (lower end). The angle adjusting mechanism 34 rotates the driving cam 37 by the driving unit, so that the upper left cord 33a and the upper right cord 33c, the lower left cord 33b, and the upper right cord 33c provided between the driving cam 37 and the driven cam 38 in the cleaning member 22. The string 33d is moved alternately in the front-back direction. And the angle adjustment mechanism 34 was connected to the upper left string 33a, the lower left string 33b, the upper right string 33c, and the lower right string 33d by moving the upper left string 33a, the lower left string 33b, the upper right string 33c, and the lower right string 33d. The standing angle of each shield plate 23 with respect to the end surface 20c of the shield case 20 is adjusted.

  The angle adjusting mechanism 34 may adjust the standing angle so as to maintain the plurality of shielding plates 23 in the above-described normal state (see FIG. 4), or may control the image forming operation of the printer 1 by a CPU or the like. May be controlled by the control unit (not shown) to adjust the standing angle of each shielding plate 23 according to the printing operation and the non-printing operation of the photosensitive drum 10. For example, during the printing operation of the photosensitive drum 10, the angle adjusting mechanism 34 adjusts the standing angle of each shielding plate 23 to be small (for example, 10 °) so as to cover the second opening 20d (see FIG. 5). On the other hand, during the non-printing operation of the photosensitive drum 10, the angle adjusting mechanism 34 adjusts the standing angle of each shielding plate 23 to be large (for example, 80 °) so as to open the second opening 20d (see FIG. 4). ).

  The expansion / contraction cords 35 are sequentially passed through through holes (not shown) provided in each shielding plate 23, and are installed between the front protection member 25 of the shield case 20 and the winding mechanism 36. The stretchable cord 35 is passed through, for example, the center of each shield plate 23 in the left-right direction and the center or upper part in the up-down direction. In this embodiment, one stretchable cord 35 is provided, but two or more stretchable cords 35 may be provided. The stretching cord 35 is expanded and contracted by winding and rewinding by the winding mechanism 36, and is always tensioned at a predetermined tension by the winding force of the winding mechanism 36, so that the positioning cord 33 is loosened. However, the standing state of each shielding plate 23 is maintained.

  The take-up mechanism 36 includes, for example, a take-up reel 39 to which the rear end of the stretchable cord 35 is fastened, and a drive unit (not shown) such as a mainspring or a motor that automatically rotates the take-up reel 39. The winding reel 39 is rotated in a predetermined winding direction by the driving unit, so that the stretchable cord 35 is automatically wound. For example, the spring-type winding mechanism 36 winds the stretchable cord 35 around the winding reel 39 in a predetermined winding direction, and then rotates the winding reel 39 in a rewinding direction opposite to the winding direction. By rewinding the stretchable cord 35 in such a manner, a winding force on the stretchable cord 35 is generated. The take-up mechanism 36 is attached to the cleaning member 22 in a state of always having a take-up force on the stretchable cord 35, and stretches the stretchable cord 35 with a predetermined tension. When the cleaning member 22 moves from the rear end side of the shield case 20 to the front end side, the winding mechanism 36 winds up the stretchable cord 35 and the cleaning member 22 moves from the front end side of the shield case 20 to the rear end side. When retracting, the retractable cord 35 is rewound.

  The blower fan 24 is provided, for example, on the front end side of the upper portion of the charging device 11, through a duct 40 provided over the shield case 20 and the plurality of shield plates 23 and in the longitudinal direction of the shield case 20. From the air.

  According to the present embodiment, as described above, the charging device 11 of the printer 1 (image forming apparatus) includes the shield case 20, the discharge wires 21, and the plurality of shielding plates 23. The shield case 20 has a first opening 20b provided on a facing surface 20a facing the photosensitive drum 10 (image carrier) and a second opening 20d provided on an end surface 20c opposite to the facing surface 20a. The discharge wire 21 is provided inside the shield case 20 along the longitudinal direction of the shield case 20 and is stretched on a side close to the facing surface 20a. The plurality of shield plates 23 are arranged at intervals in the longitudinal direction of the shield case 20, and are erected on the second opening 20d side with respect to the end surface 20c.

  Accordingly, in the charging device 11, the plurality of shielding plates 23 prevent the static elimination light of the static eliminator 15 and the reflected light from entering the shield case 20 through the second opening 20 d. It is possible to avoid a decrease in charging potential. Further, in the charging device 11, the plurality of shielding plates 23 guide the air from the blower fan 24 to the shield case 20 through the second opening 20d, so that the air can be sent into the shield case 20. The stagnation of discharge products around the discharge wire 21 can be avoided.

  Further, according to the present embodiment, the charging device 11 is provided on one end side (rear end side) of the shield case 20 in the longitudinal direction, and along the end surface 20c, one end side (rear end side) of the shield case 20 in the longitudinal direction. ) And the other end side (front end side), a cleaning member 22 for cleaning the discharge wire 21 while reciprocating. The plurality of shielding plates 23 are formed in a blind shape that can expand and contract in the longitudinal direction of the shield case 20 according to the reciprocating movement of the cleaning member 22.

  Thereby, the plurality of shielding plates 23 can be provided without obstructing the cleaning of the discharge wires 21 by the cleaning member 22.

  Further, according to the present embodiment, the charging device 11 further includes an angle adjusting mechanism 34 that can adjust the standing angle of the plurality of shielding plates 23 with respect to the end surface 20c.

  This makes it possible to adjust the standing angles of the plurality of shielding plates 23 to avoid the penetration of static elimination light or the like into the shield case 20 and optimize the blowing of air into the shield case 20. Further, it is also possible to adjust the standing angles of the plurality of shielding plates 23 according to the configuration and specifications of the printer 1, the image forming unit 6, or the charging device 11.

  Further, according to the present embodiment, during the printing operation using the photosensitive drum 10, the angle adjusting mechanism 34 adjusts the standing angle of the plurality of shielding plates 23 to cover the second opening 20 d to be small, At the time of non-printing operation using the body drum 10, the standing angles of the plurality of shielding plates 23 are largely adjusted so as to open the second opening 20d.

  Thereby, at the time of the printing operation in which the static elimination light is generated by the static eliminator 15, the second opening 20d is covered with the plurality of shielding plates 23, so that the penetration of the static elimination light or the like into the shield case 20 can be more reliably avoided. it can. In a non-printing operation in which static elimination light is not generated, by opening the second opening 20d, more air can be blown into the shield case 20 and the accumulation of discharge products around the discharge wire 21 can be reduced. This can be avoided more reliably.

  In the present embodiment, the configuration including the positioning cord 33, the angle adjusting mechanism 34, the telescopic cord 35, and the winding mechanism 36 as the attachment mechanism 32 of the plurality of shielding plates 23 has been described. The mounting mechanism 32 of the plate 23 is not limited to this configuration, and another blind type configuration may be used as long as the plurality of shielding plates 23 can expand and contract in accordance with the movement of the cleaning member 22. In another embodiment, the position where the positioning cord 33 is attached to each shield plate 23 and the position where the telescopic cord 35 is attached may be reversed. Further, in another embodiment, the winding mechanism 36 may be provided on the front protection member 25 or the rear protection member 26. Further, in another embodiment, the angle adjusting mechanism 34 may be provided on the rear protection member 26 or the cleaning member 22.

  In the present embodiment, the example in which the charging device 11 includes the blower fan 24 that blows air into the shield case 20 has been described. However, in other embodiments, the charging device 11 does not include the blower fan 24, and The air may be received from another provided blower fan.

  In the present embodiment, the case where the configuration of the present invention is applied to the printer 1 has been described. However, in another different embodiment, the configuration of the present invention is applied to another image forming apparatus such as a copying machine, a facsimile, and a multifunction peripheral. It is also possible.

1 Printer (image forming device)
6 Image forming unit 10 Photoconductor drum (image carrier)
DESCRIPTION OF SYMBOLS 11 Charging device 15 Static eliminator 20 Shield case 20a Opposing surface 20b 1st opening 20c End surface 20d 2nd opening 21 Discharge wire 22 Cleaning member 23 Shielding plate 24 Blower fan 30 Cleaning case 31 Wire cleaning part 32 Mounting mechanism 34 Angle adjustment mechanism

Claims (5)

A shield case having a first opening provided on a facing surface facing the image carrier and a second opening provided on an end surface opposite to the facing surface;
A discharge wire provided in the shield case along the longitudinal direction of the shield case and stretched on a side close to the facing surface,
The shield case is disposed at intervals in the longitudinal direction, and shields light incident on the shield case through the second opening during the printing operation of the image carrier. as printing during operation causes air to flow into the shield case through the second opening, said second opening plurality of adjustable upright angle against the end face at the side shielding plate,
A charging device comprising: A cleaning member is provided at one end in the longitudinal direction of the shield case, and cleans the discharge wire while reciprocating between the one end and the other end in the longitudinal direction of the shield case along the end surface. ,
2. The charging device according to claim 1, wherein the plurality of shielding plates are configured in a blind shape that can expand and contract in a longitudinal direction of the shield case in accordance with a reciprocating movement of the cleaning member. 3.   The charging device according to claim 2, further comprising an angle adjustment mechanism that can adjust an upright angle of the plurality of shielding plates with respect to the end surface.   The angle adjusting mechanism adjusts the standing angle of the plurality of shielding plates to be small so as to cover the second opening during the printing operation of the image carrier, and the second angle during the non-printing operation of the image carrier. 4. The charging device according to claim 3, wherein the upright angles of the plurality of shielding plates are adjusted so as to open the opening. 5.   An image forming apparatus comprising the charging device according to claim 1.

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