Electrifying device, image forming unit, and image forming apparatus

Abstract

To improve cleanability of a control electrode while avoiding contact of the control electrode with a surface of a body to be electrified, compared with a case where the control electrode is cleaned in the same shape as that during electrification.SOLUTION: An electrifying device comprises: a discharge electrode; a control electrode that is arranged between the discharge electrode and a body to be electrified, which is electrified by the discharge electrode, and is curved or bent along a surface shape of the body to be electrified; cleaning means that, of the discharge electrode and the control electrode, cleans at least the control electrode; and deformation means that deforms the shape of the control electrode into different shapes between during cleaning performed by the cleaning means and during electrification.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a charging device, an image forming unit, and an image forming apparatus. [Background technology]

[0002] Conventionally, techniques relating to charging devices have already been proposed, for example, as disclosed in Patent Documents 1 and 2.

[0003] In Patent Document 1, the control electrode is arranged in a shape that follows the curvature of the body to be charged so that the distance between the body to be charged and the control electrode does not vary depending on the location, and the surface of the control electrode opposite the body to be charged is cleaned by a cleaning member (

[0022] ,

[0028] ).

[0004] In Patent Document 2, both surfaces of a control electrode formed in a planar shape can be cleaned by a cleaning member (

[0056] , [Fig. 4]). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-086091 [Patent Document 2] Japanese Patent Application Publication No. 2019-045801 Summary of the Invention [Problem to be solved by the invention]

[0006] The object of the present invention is to improve the cleaning properties of the control electrode while avoiding contact of the control electrode with the surface of the body to be charged, compared to when the control electrode is cleaned while maintaining the same shape as when it was charged. [Means for solving the problem]

[0007] The invention described in claim 1 comprises a discharge electrode, a control electrode disposed between the discharge electrode and a body to be charged by the discharge electrode, the control electrode being curved or bent along the surface shape of the body to be charged; a cleaning means for cleaning at least the control electrode out of the discharge electrode and the control electrode; a deformation means for deforming the shape of the control electrode into different shapes when the control electrode is cleaned by the cleaning means and when the control electrode is charged; The charging device is provided with:

[0008] The invention described in claim 2 is a charging device described in claim 1, in which the control electrode is stretched with tension applied in a direction intersecting the rotation direction of the charged body, and is held in a curved or bent shape that follows the surface shape of the charged body by a holding member.

[0009] The invention described in claim 3 is the charging device described in claim 2, wherein the deformation means reduces the tension of the control electrode during cleaning, thereby deforming the control electrode into a shape different from that during charging.

[0010] The invention described in claim 4 is a charging device described in claim 1, in which at least one end of the control electrode along a direction intersecting the rotation direction of the charged body is urged outward toward the charging area of ​​the charged body by a tension member.

[0011] The invention described in claim 5 is a charging device described in claim 4, in which the deformation means changes the position at which the tension member tensions the other end of the control electrode inward with respect to the charging area of ​​the charged body along a direction intersecting the rotation direction of the charged body, thereby deforming the control electrode into a shape different from that when charged.

[0012] A sixth aspect of the present invention is the charging device according to the first aspect, wherein the deformation means changes the shape of a holding portion that holds the control electrode from a curved or bent shape to a flat shape.

[0013] The invention described in claim 7 is the charging device described in claim 6, wherein the deformation means has a holding member that holds one end of the control electrode along a direction that intersects with the rotation direction of the charged body, and the holding member has a curved portion that curves or bends the control electrode to follow the surface shape of the charged body when charging, and a flat portion that deforms the shape of the control electrode into a flat shape different from when it is charged when cleaning.

[0014] The invention described in claim 8 is a charging device described in claim 1, in which the control electrode, when charging, is pressed against a regulating member provided on the charged body side, thereby becoming curved in accordance with the surface shape of the charged body.

[0015] The invention described in claim 9 is the charging device described in claim 8, wherein the deformation means changes the position of the charging device in a direction away from the charged body, thereby deforming the shape of the control electrode into a shape different from that when charged.

[0016] The invention described in claim 10 is the charging device described in claim 1, wherein the deformation means deforms the shape of the control electrode into a shape different from that when charged, and further changes the position of the charging device in a direction away from the charged body.

[0017] The invention described in claim 11 is a charging device described in claim 1, in which the deformation means deforms the shape of the control electrode into a shape different from that when charged by pressing both ends of the control electrode along a direction intersecting the rotation direction of the charged body.

[0018] The invention described in claim 12 is the charging device described in claim 11, wherein the deformation means has a pressing member that presses both ends of the control electrode along a direction intersecting the rotation direction of the charged body, and the pressing member has a pressing portion that deforms the control electrode into a planar shape.

[0019] The invention described in claim 13 is the charging device according to claim 1, wherein the cleaning means cleans both the discharge electrode and the control electrode.

[0020] The invention described in claim 14 is a charging device described in claim 13, wherein the cleaning means has a first cleaning member that contacts the discharge electrode and a second cleaning member that contacts both the front and back surfaces of the control electrode that has been deformed into a shape different from when it is charged.

[0021] The invention described in claim 15 includes the charging device according to any one of claims 1 to 14, This is an image forming unit that is detachably attached to an image forming apparatus.

[0022] The invention described in claim 16 comprises an image holding means, a charging means for charging the surface of the image holding means; an electrostatic latent image forming means for forming an electrostatic latent image on the surface of the image holding means charged by the charging means; Equipped with The image forming apparatus uses the charging device according to any one of claims 1 to 14 as the charging means. [Effects of the Invention]

[0023] According to the invention described in claim 1, the cleaning ability of the control electrode can be improved while preventing the control electrode from coming into contact with the surface of the body to be charged, compared to when the control electrode is cleaned while maintaining the same shape as when it was charged.

[0024] According to the invention described in claim 2, the control electrode can be a flat control electrode, compared to when the control electrode is formed in a curved or bent shape along the surface shape of the body to be charged without using a holding member.

[0025] According to the invention described in claim 3, the deformation means can easily deform the control electrode into a shape different from the shape when charged by simply reducing the tension, compared to when an external force is applied to the control electrode to deform it into a shape different from the shape when charged during cleaning.

[0026] According to the invention as recited in claim 4, the control electrode can simplify the structure for biasing the control electrode outward with respect to the charging area of ​​the body to be charged, compared to when no tension member is used.

[0027] According to the invention as defined in claim 5, the deformation means simplifies the structure of the tension member compared to when the tension member changes the positions of both ends of the control electrode.

[0028] According to the sixth aspect of the invention, the deformation means can be configured more easily than when the shape of the deformation means is changed other than the shape of the holding portion that holds the control electrode.

[0029] According to the invention described in claim 7, the deformation means makes it possible to deform the shape of the control electrode using a single holding member, compared to when the curved portion and the flat portion are provided on different holding members.

[0030] According to the invention described in claim 8, the control electrode can be easily bent or curved during charging, compared to when the control electrode is curved or curved by regulating members provided on both the charging device and the charged body side.

[0031] According to the invention described in claim 9, the deformation means can easily change the shape of the control electrode by simply changing the position of the charging means, compared to when the tension of the control electrode is changed.

[0032] According to the invention described in claim 10, it is possible to clean both the front and back surfaces of the control electrode in accordance with the surface shape of the body to be charged while preventing the cleaning means from coming into contact with the surface of the body to be charged.

[0033] According to the invention as set forth in claim 11, the deformation means can more reliably deform the shape of the control electrode than when the tension of the control electrode is changed.

[0034] According to the invention described in claim 12, the deformation means is a member that presses both ends of the control electrode along the longitudinal direction, and can reliably deform the control electrode into a planar shape compared to a case in which there is no pressing member having a pressing portion that deforms the control electrode into a planar shape.

[0035] According to the invention as set forth in claim 13, the structure of the cleaning means can be simplified compared to when the cleaning means cleans only the control electrode.

[0036] According to the invention described in claim 14, the cleaning means is capable of cleaning both the discharge electrode and the control electrode, compared to a case in which the cleaning means does not have a first cleaning member that contacts the discharge electrode and a second cleaning member that contacts both the front and back surfaces of the control electrode that has been deformed into a shape different from when it is charged.

[0037] According to the invention described in claim 15, compared to a case in which the charging device described in any one of claims 1 to 14 is not provided, it is possible to clean both the front and back sides of the control electrode that is curved along the surface shape of the body to be charged while preventing the cleaning means from coming into contact with the surface of the body to be charged.

[0038] According to the invention described in claim 16, compared to when a charging device described in any of claims 1 to 14 is not used as the charging means, it is possible to clean both the front and back sides of the control electrode that is curved along the surface shape of the body to be charged while preventing the cleaning means from coming into contact with the surface of the body to be charged. [Brief explanation of the drawings]

[0039] [Figure 1] 1 is an overall configuration diagram showing an image forming apparatus to which a charging device according to a first embodiment of the present invention is applied; [Figure 2] 1 is a configuration diagram showing an image forming device of an image forming apparatus according to a first embodiment of the present invention; [Figure 3] 1 is a perspective view showing the configuration of an image forming unit according to a first embodiment of the present invention; [Figure 4]1 is a perspective view showing the configuration of a unit main body of an image forming unit according to a first embodiment of the present invention; [Figure 5] 1 is a perspective view showing the configuration of a grid electrode of a charging device according to a first embodiment of the present invention; [Figure 6] FIG. 3 is a configuration diagram showing a control unit for a grid electrode. [Figure 7] FIG. 4 is a diagram showing the configuration of a connection portion of a grid electrode. [Figure 8] 1 is a perspective view showing the configuration of a charging device according to a first embodiment of the present invention. [Figure 9] 1 is a perspective view showing an insulating block at the rear end of a charging device according to a first embodiment of the present invention; [Figure 10] 1 is a perspective view showing an insulating block at the front end of a charging device according to a first embodiment of the present invention; [Figure 11] FIG. 2 is a structural diagram showing a tension member. [Figure 12] FIG. 2 is a cross-sectional view showing a main part of an insulating block at the front end. [Figure 13] FIG. 2 is a perspective view showing the configuration of the cleaning device. [Figure 14] FIG. 2 is a perspective view showing the configuration of the cleaning device. [Figure 15] FIG. 2 is a perspective view showing the configuration of the cleaning device. [Figure 16] FIG. 2 is a configuration diagram showing a swing arm. [Figure 17] FIG. 2 is a configuration diagram showing a swing arm. [Figure 18] FIG. 10 is a configuration diagram showing the operation of the tension member. [Figure 19] 1 is a perspective view showing the operation of a charging device according to a first embodiment of the present invention; [Figure 20] FIG. 4 is a diagram illustrating a state in which the grid electrode is cleaned by the cleaning device. [Figure 21] FIG. 4 is a diagram illustrating a state in which the grid electrode is cleaned by the cleaning device. [Figure 22] FIG. 10 is a perspective view showing the configuration of a main part of a charging device according to a second embodiment of the present invention. [Figure 23] FIG. 2 is a perspective view showing a holding member. [Figure 24] FIG. 10 is a perspective view showing the operation of a charging device according to a second embodiment of the present invention. [Figure 25] FIG. 10 is a front view illustrating the operation of a charging device according to a third embodiment of the present invention. [Figure 26] FIG. 10 is a configuration diagram showing an image forming device of an image forming apparatus according to a fourth embodiment of the present invention. [Figure 27] FIG. 10 is a schematic diagram illustrating a modified example of the charging device. [Figure 28] FIG. 10 is a structural diagram showing a charging device according to a fourth embodiment of the present invention. [Figure 29] FIG. 10 is a structural diagram showing a modified example of a charging device according to the fourth embodiment of the present invention. [Figure 30] FIG. 10 is a structural diagram showing a further modified example of the charging device according to the fourth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0040] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0041] [Embodiment 1] FIG. 1 is a schematic diagram showing the overall configuration of an image forming apparatus to which a charging device and an image forming unit according to a first embodiment of the present invention are applied.

[0042] <Overall configuration of image forming apparatus> The image forming apparatus 1 according to the first embodiment is configured as, for example, a color printer. As shown in FIG. 1 , the image forming apparatus 1 includes a plurality of image creating devices 10, an intermediate transfer device 20, a paper feeder 50, a fixing device 40, and the like. The plurality of image creating devices 10 form toner images developed with toner constituting a developer. The intermediate transfer device 20 holds each toner image formed by the image creating devices 10 and transports it to a secondary transfer position where the toner image is finally secondarily transferred onto a recording sheet 5, an example of a recording medium. The paper feeder 50 stores and transports the required recording sheet 5 to be supplied to the secondary transfer position of the intermediate transfer device 20. The fixing device 40 fixes the toner image on the recording sheet 5 secondarily transferred by the intermediate transfer device 20. Note that the two-dot chain lines in the figure indicate the main transport paths along which the recording sheet 5 is transported within the image forming apparatus 1.

[0043] The image forming device 10 is composed of four image forming devices 10Y, 10M, 10C, and 10K that are dedicated to forming toner images of four colors, yellow (Y), magenta (M), cyan (C), and black (K), respectively. These four image forming devices 10 (Y, M, C, K) are arranged in a horizontal row in the internal space of the image forming device 1.

[0044] As shown in FIG. 2 , each image forming device 10 (Y, M, C, K) includes a rotating photosensitive drum 11 serving as an example of a charged body and an image holding unit. Around the photosensitive drum 11 are charging devices 12 (Y, M, C, K) serving as an example of a charging unit according to the first embodiment, exposure devices 13 (Y, M, C, K) serving as an example of an electrostatic latent image forming unit, developing devices 14 (Y, M, C, K), primary transfer devices 15 (Y, M, C, K), and drum cleaning devices 16 (Y, M, C, K). The charging devices 12 charge the image-forming peripheral surface (image holding surface) of the photosensitive drum 11 to a desired potential. The exposure devices 13 irradiate the charged peripheral surface of the photosensitive drum 11 with light based on image information (signals) to form electrostatic latent images (for each color) with potential differences. The developing device 14 develops the electrostatic latent image with developer toner of the corresponding color (Y, M, C, K) to form a toner image. The primary transfer device 15 transfers each toner image to the intermediate transfer device 20. The drum cleaning device 16 removes and cleans the toner and other adhering matter remaining on the image bearing surface of the photosensitive drum 11 after the primary transfer.

[0045] The photoreceptor drum 11 has an image bearing surface formed on the circumferential surface of a grounded cylindrical or columnar substrate, the image bearing surface having a photoconductive layer (photosensitive layer) made of a photosensitive material. The substrate of the photoreceptor drum 11 is grounded. The photoreceptor drum 11 is supported so that it rotates in the direction indicated by arrow A, which is an example of the movement direction, by a driving force transmitted from a driving means (not shown). As shown in FIG. 2, the surface shape of the photoreceptor drum 11 is curved in a circular shape with a required radius of curvature about the rotation axis.

[0046] The charging device 12 is a so-called scorotron charger disposed at a distance from the photosensitive drum 11. The scorotron charging device 12 has a higher charging capability for the photosensitive drum 11 than a roll-shaped charging roll. Therefore, the scorotron charging device 12 is particularly effective in a highly productive image forming apparatus 1 in which the rotation speed of the photosensitive drum 11, which determines the process speed, is increased. A charging voltage and a control voltage are supplied to the charging device 12. If the developing device 14 performs reversal development, the charging voltage is a voltage or current of the same polarity as the charging polarity of the toner supplied from the developing device 14. The configuration of the charging device will be described in detail later.

[0047] The exposure device 13 is an LED print head that forms an electrostatic latent image by irradiating the photosensitive drum 11 with light corresponding to image information using LEDs (Light Emitting Diodes) as a plurality of light-emitting elements arranged along the axial direction of the photosensitive drum 11. Note that the exposure device 13 may also be one that deflects and scans laser light configured according to the image information along the axial direction of the photosensitive drum 11.

[0048] As shown in FIG. 2, each of the developing devices 14 (Y, M, C, K) is configured by arranging a developing roll 141, an agitation supply member 142, a developer supply roll 143, an agitation transport member 144, a layer thickness regulating member 145, and the like inside a housing 140. The housing 140 has an opening facing the photosensitive drum 11 and a developer storage chamber formed therein. The developing roll 141 holds the developer and transports it to a development area facing the photosensitive drum 11. The agitation supply member 142 is made of a screw auger or the like that agitates the developer while feeding it so that it passes through the developing roll 141. The developer supply roll 143 supplies the developer supplied from the agitation supply member 142 to the developing roll 141. The agitation transport member 144 is made of a screw auger or the like that agitates the developer while feeding it to the agitation supply member 142. The layer thickness regulating member 145 regulates the amount (layer thickness) of developer held on the developing roll 141. A developing voltage is supplied to the developing device 14 from a power supply device (not shown) between the developing roll 141 and the photosensitive drum 11. As the four-color developer, for example, a two-component developer containing non-magnetic toner and magnetic carrier is used.

[0049] The primary transfer device 15 (Y, M, C, K) is a contact type transfer device equipped with a primary transfer roll that rotates in contact with the periphery of the photosensitive drum 11 via the intermediate transfer belt 21 and is supplied with a primary transfer voltage. As the primary transfer voltage, a DC voltage showing a polarity opposite to the charge polarity of the toner is supplied from a power supply device (not shown).

[0050] The drum cleaning device 16 is composed of a main body 160, a cleaning brush 161, a cleaning plate 162, a sending member 163, etc. The main body 160 is formed in the shape of a container with a portion open. The cleaning brush 161 is positioned so as to contact the circumferential surface of the photosensitive drum 11 after primary transfer with a required pressure to scrape off and clean any remaining toner and other adhering matter. The cleaning plate 162 is positioned so as to contact the circumferential surface of the photosensitive drum 11 with a required pressure to remove and clean any remaining toner and other adhering matter. The sending member 163 is composed of a screw auger or the like that collects the toner and other adhering matter removed by the cleaning brush 161 and cleaning plate 162 and transports them to a collection system (not shown). The cleaning plate 162 is a plate-shaped member (e.g., a blade) made of a material such as rubber.

[0051] A discharge lamp 17 is disposed between the drum cleaning device 16 and the charging device 12. The discharge lamp 17 discharges the surface of the photosensitive drum 11 from which the drum cleaning device 16 has removed residual toner and other adhering matter by uniformly exposing the surface to light.

[0052] As shown in FIG. 1, the intermediate transfer device 20 is positioned vertically below each of the image forming devices 10 (Y, M, C, K). The intermediate transfer device 20 is primarily composed of an intermediate transfer belt 21, multiple belt support rolls 22-24, a secondary transfer device 30, and a belt cleaning device 25. The intermediate transfer belt 21 rotates in the direction indicated by arrow B while passing through a primary transfer position between the photosensitive drum 11 and the primary transfer device 15 (primary transfer roll). The multiple belt support rolls 22-24 support the intermediate transfer belt 21 rotatably, maintaining it in a desired state from its inner surface. The secondary transfer device 30 is positioned on the outer peripheral surface (image bearing surface) of the intermediate transfer belt 21 supported by the belt support roll 24, and performs a secondary transfer of the toner image on the intermediate transfer belt 21 to the recording paper 5. The belt cleaning device 25 removes and cleans any remaining toner, paper dust, and other debris that remains on the outer peripheral surface of the intermediate transfer belt 21 after passing through the secondary transfer device 30.

[0053] The intermediate transfer belt 21 is an endless belt made of a material in which a resistance adjuster such as carbon black is dispersed in a synthetic resin such as polyimide resin or polyamide resin. The belt support roll 22 is configured as a drive roll that is rotationally driven by a drive device (not shown). The belt support roll 23 is configured as a surface-finishing roll that holds the image forming surface of the intermediate transfer belt 21. The belt support roll 24 is configured as an opposing roll that faces the secondary transfer device 30. The belt support roll 22 also functions as a support roll that supports the back surface of the belt cleaning device 25.

[0054] 1, the secondary transfer device 30 is a contact-type transfer device equipped with a secondary transfer roll 31. The secondary transfer roll 31 rotates in contact with the circumferential surface of the intermediate transfer belt 21 at a secondary transfer position, which is the outer circumferential surface of the intermediate transfer belt 21 supported by the belt support roll 24 in the intermediate transfer device 20, and a secondary transfer voltage is supplied to the secondary transfer roll 31 or the belt support roll 24 of the intermediate transfer device 20. A DC voltage having the same or opposite polarity as the charge polarity of the toner is supplied as a secondary transfer voltage from a power supply device (not shown).

[0055] The fixing device 40 is configured by arranging a heating rotor 42, a pressure rotor 43, and other components inside a housing 41. The housing 41 is formed with an inlet and outlet for the recording paper 5. The heating rotor 42 is formed in the form of a belt or roll that rotates in the direction indicated by the arrow and is heated by a heating means so that the surface temperature is maintained at a predetermined temperature. The pressure rotor 43 is formed in the form of a roll or belt that rotates in contact with the heating rotor 42 at a predetermined pressure and rotates substantially along the axial direction of the heating rotor 42. In this fixing device 40, the contact area between the heating rotor 42 and the pressure rotor 43 forms the fixing nip N where the required fixing process (heating and pressure) is performed.

[0056] The paper feeder 50 is disposed below the intermediate transfer device 20. The paper feeder 50 is mainly composed of one (or more) paper containers 51 and feeders 52 and 53. The paper container 51 stores a stack of recording paper 5 of a desired size, type, etc. The feeders 52 and 53 feed the recording paper 5 one sheet at a time from the paper container 51. The paper container 51 is arranged so that it can be pulled out, for example, from the front side of the device main body (the side that the user faces when operating the device).

[0057] Examples of the recording paper 5 include plain paper used in electrophotographic copiers, printers, etc., thin paper such as tracing paper, and overhead projector sheets. To further improve the smoothness of the image surface after fixing, it is preferable that the surface of the recording paper 5 is as smooth as possible, and for example, coated paper in which the surface of plain paper is coated with a resin or the like, or so-called thick paper with a relatively large basis weight such as art paper for printing, can also be suitably used.

[0058] Between the paper feed device 50 and the secondary transfer device 30, there are provided one or more pairs of paper transport rolls 54, 55 and a paper feed transport path 56. The paper transport rolls 54, 55 transport the recording paper 5 fed from the paper feed device 50 to the secondary transfer position. The paper feed transport path 56 is formed by a transport guide (not shown). The paper transport roll pair 55, which is disposed in the paper feed transport path 56 immediately before the secondary transfer position, is configured as, for example, a roll (registration roll) that adjusts the transport timing of the recording paper 5. Between the secondary transfer device 30 and the fixing device 40, there are provided one or more pairs of paper transport rolls 57, 58 and a paper transport path 59 for transporting the recording paper 5 fed from the secondary transfer device 30 after the secondary transfer to the fixing device 40. A paper discharge unit (not shown) is provided on the side of the image forming apparatus 1 to discharge the recording paper 5 fed from the fixing device 40 after the fixing.

[0059] The image forming apparatus 1 may be provided with a double-sided paper transport path (not shown) for forming images on both sides of the recording paper 5.

[0060] 1, reference numeral 100 indicates a control device that comprehensively controls the operation of the image forming apparatus 1. The control device 100 includes a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), which are not shown, as well as buses and communication interfaces that connect the CPU, ROM, etc.

[0061] <Configuration of image forming unit> 2, the image forming apparatus 1 according to the first embodiment includes a plurality of image forming units 200 corresponding to the respective image forming devices 10 (Y, M, C, K) in order to improve ease of maintenance, etc. Each image forming unit 200 is configured by integrating a plurality of members, including at least the photosensitive drum 11, from among the members constituting the respective image forming devices 10 (Y, M, C, K) of yellow (Y), magenta (M), cyan (C), and black (K). Each image forming unit 200 is individually detachable from the image forming apparatus 1.

[0062] In this embodiment 1, as shown in Fig. 2, the photosensitive drum 11, charging device 12, and drum cleaning device 16 are integrally configured as an image forming unit 200. The charging device 12 may be configured to be detachable and separate from the photosensitive drum 11 and drum cleaning device 16. The image forming unit 200 is replaced with a new one not only when the photosensitive drum 11 and other components reach the end of their life, but also when the charging device 12 or drum cleaning device 16 breaks down. If the image forming unit 200 does not include the developing device 14, it is possible to use a common image forming unit 200 corresponding to all of the imaging devices 10 (Y, M, C, K).

[0063] As shown in Fig. 3, the image forming unit 200 includes a unit main body 201. The unit main body 201 has front and rear support portions 202 and 203 that rotatably support both axial ends of the photosensitive drum 11, and a connecting portion 204 that connects the front and rear support portions 202 and 203 on one side of the photosensitive drum 11. As shown in Fig. 4, the front and rear support portions 202 and 203 are provided with front and rear positioning portions 205 and 206 that position both longitudinal ends of the charging device 12. The front and rear positioning portions 205 and 206 are each provided with positioning holes 205a and 205b and 206a and 206b that position the charging device 12.

[0064] The front and rear support portions 202, 203 of the unit main body 201 are provided with curved portions 207, 208 that support the grid electrode 122 of the charging device 12 in a curved shape that follows the surface shape of the photosensitive drum 11 when the charging device 12 is attached. The curved portions 207, 208 are formed in an arc shape that protrudes a required distance from the surface of the photosensitive drum 11, which is rotatably attached to the image forming unit 200. The height of the curved portions 207, 208 determines the gap (DGS) between the surface of the photosensitive drum 11 and the grid electrode 122 of the charging device 12.

[0065] Furthermore, the connecting portion 204 of the unit main body 201 also serves as the main body 160 of the drum cleaning device 16. A drive shaft 209 is rotatably attached to the upper portion of the charging device 12. The drive shaft 209 drives a cleaning device 70 (described later) that cleans the charging device 12 along the axial direction of the photosensitive drum 11. Spiral convex portions 209a are provided at a large pitch on the outer circumferential surface of the drive shaft 209. An adapter portion 209b is provided at the rear end of the drive shaft 209 along the axial direction to transmit driving force from the image forming apparatus 1 when the image forming unit 200 is attached to the image forming apparatus 1.

[0066] The image forming unit 200 is configured to be insertable and removable along a depth direction intersecting with the width direction of the image forming device 1 through an opening provided on the front of the device body (not shown) of the image forming device 1 when the front cover (not shown) of the image forming device 1 is open.

[0067] <Operation of image forming device> The basic image forming operation of the image forming apparatus 1 will be described below.

[0068] Here, we will explain the operation in full-color mode, in which the four image forming devices 10 (Y, M, C, K) are used to form a full-color image composed of a combination of toner images of four colors (Y, M, C, K).

[0069] When the image forming apparatus 1 receives image information and command information requesting a full-color image forming operation (printing) from a personal computer or image reading device (not shown), the control device 100 starts the four image forming devices 10 (Y, M, C, K), the intermediate transfer device 20, the secondary transfer device 30, the fixing device 40, etc.

[0070] 1, in each imaging device 10 (Y, M, C, K), first, each photosensitive drum 11 rotates in the direction indicated by arrow A, and each charging device 12 charges the surface of each photosensitive drum 11 to a required polarity (negative polarity in the first embodiment) and potential. Next, exposure device 13 irradiates the surface of the charged photosensitive drum 11 with light emitted based on image signals obtained by converting the light into each color component (Y, M, C, K), and forms electrostatic latent images of each color component, each composed of a required potential difference, on the surface.

[0071] Next, each developing device 14 (Y, M, C, K) supplies toner of the corresponding color (Y, M, C, K) charged to the required polarity (negative polarity) from the developing roll 141 to electrostatically adhere to the electrostatic latent image of each color component formed on the photosensitive drum 11, thereby developing the image. Through this development, the electrostatic latent image of each color component formed on each photosensitive drum 11 is visualized as a toner image of four colors (Y, M, C, K) developed with the toner of the corresponding color.

[0072] Next, when the toner images of each color formed on the photosensitive drum 11 of each image forming device 10 (Y, M, C, K) are transported to the primary transfer position, the primary transfer device 15 (Y, M, C, K) performs primary transfer of the toner images of each color so that they are superimposed in order onto the intermediate transfer belt 21 rotating in the direction indicated by arrow B of the intermediate transfer device 20.

[0073] Furthermore, in each imaging device 10 (Y, M, C, K) where the primary transfer has been completed, the drum cleaning device 16 scrapes off any adhering matter to clean the surface of the photosensitive drum 11. This makes each imaging device 10 (Y, M, C, K) ready for the next image formation operation.

[0074] Next, the intermediate transfer device 20 holds the primarily transferred toner image and transports it to the secondary transfer position by the rotation of the intermediate transfer belt 21. Meanwhile, the paper feeder 50 sends out the required recording paper 5 to a paper feed path 56 in accordance with the image creation operation. In the paper feed path 56, a pair of paper transport rolls 55, which act as registration rolls, feeds and supplies the recording paper 5 to the secondary transfer position in accordance with the transfer timing.

[0075] At the secondary transfer position, the secondary transfer device 30 performs secondary transfer of the toner images on the intermediate transfer belt 21 all at once onto the recording paper 5. After the secondary transfer is completed in the intermediate transfer device 20, the belt cleaning device 25 removes and cleans the surface of the intermediate transfer belt 21 to remove any toner or other adhering matter remaining thereon after the secondary transfer.

[0076] Next, the recording paper 5 onto which the toner image has been secondarily transferred is peeled off from the intermediate transfer belt 21 and then transported to the fixing device 40 via a paper transport path 59. In the fixing device 40, the recording paper 5 after the second transfer is introduced into and passes through a contact area between the rotating heating rotor 42 and the pressure rotor 43, thereby performing the necessary fixing process (heating and pressurizing) to fix the unfixed toner image onto the recording paper 5. Finally, the recording paper 5 after fixing is discharged to a paper discharge section, for example, installed on the side of the device main body (not shown).

[0077] By the above operation, the recording paper 5 is outputted on which a full color image formed by combining four color toner images is formed.

[0078] <Configuration of charging device> 2 and 3, the charging device 12 according to this embodiment 1 is disposed along the axial direction of the photosensitive drum 11, which is an example of a direction intersecting with the rotation direction A of the photosensitive drum 11. Here, the axial direction of the photosensitive drum 11 is the longitudinal direction of the charging device 12. In FIG. 3, the symbol L indicates the longitudinal direction of the charging device 12, W indicates the width direction of the charging device 12, and H indicates the height direction of the charging device 12.

[0079] 3 shows a case where the charging device 12 is disposed directly above the photosensitive drum 11, and the height direction H of the charging device 12 coincides with the vertical direction. However, the charging device 12 is not limited to being disposed directly above the photosensitive drum 11, and may be disposed at an oblique position along the circumferential direction of the photosensitive drum 11. In this case, the height direction H of the charging device 12 is different from the vertical direction.

[0080] As shown in FIG. 2, the charging device 12 broadly comprises a shield case 120 as an example of a housing, one or more (two in the illustrated example) discharge wires 121, 121 as an example of a discharge electrode, and a grid electrode 122 as an example of a control electrode.

[0081] The shield case 120 is made of a metal such as stainless steel or aluminum. The shield case 120 functions as an opposing electrode when a high voltage is applied to the discharge wires 121, 121 to generate a corona discharge. The shield case 120 is formed in the shape of a rectangular parallelepiped elongated along the axial direction of the photosensitive drum 11, with an opening 123 that is open on the entire surface facing the photosensitive drum 11 (the bottom surface in the figure). The shield case 120 includes a top wall 120a, left and right side walls 120b, 120c, and a partition wall 120d. The top wall 120a is located at the upper end opposite the photosensitive drum 11. The left and right side walls 120b, 120c are provided by bending downward from both ends along the width direction of the top wall 120a so as to face the photosensitive drum 11. The partition wall 120d divides the space within the shield case 120 in the width direction, which is the rotation direction A of the photosensitive drum 11, in accordance with the number of discharge wires 121, 121. If there is one discharge wire 121, the partition wall 120d is not provided. If there are three or more discharge wires 121, the partition wall 120d is provided to separate the discharge wires 121, 121.... The shield case 120 is either applied with the same high voltage as the grid electrode 122 or is grounded. The cylindrical or columnar conductive base of the photosensitive drum 11 is grounded.

[0082] An air outlet 120e is opened in the center of the width direction and along the entire length of the shield case 120 in the ceiling wall 120a of the shield case 120 to send air into the inside of the shield case 120. The air outlet 120e sends air toward the surface of the photosensitive drum 11, thereby removing discharge products such as ozone generated by corona discharge.

[0083] The discharge wires 121, 121 are made of tungsten, carbon tungsten, gold-plated tungsten, etc. A negative high voltage of several K to approximately 8 KV is applied to the discharge wires 121, 121 by a high voltage power supply (not shown), for example.

[0084] The grid electrode 122 is arranged in an opening 123 of the shield case 120 facing the photosensitive drum 11, in a state of being curved in an arc along the surface shape of the photosensitive drum 11. A high voltage substantially equal to a desired potential is applied to the grid electrode 122 by, for example, a high voltage power supply (not shown) to set the photosensitive drum 11 to a desired charging potential.

[0085] As shown in FIG. 5 , the grid electrode 122 is formed into a thin, elongated rectangular flat plate corresponding to the opening 123 of the shielding case 120 by etching or pressing a thin plate-like member made of a metal such as tungsten, carbon tungsten, or gold-plated tungsten. The grid electrode 122 integrally includes a control unit 122a and connecting units 122b and 122c. The control unit 122a is provided over the entire area of ​​the grid electrode 122 except for both longitudinal ends. The connecting units 122b and 122c are provided at both longitudinal ends of the control unit 122a. A short, strip-shaped boundary 122d is provided between the control unit 122a and the connecting units 122b and 122c along the longitudinal direction. The control unit 122a of the grid electrode 122 has slightly wider, strip-shaped edge units 122e and 122e at both widthwise ends. The control section 122a is divided at its center along the width direction by a strip-shaped dividing section 122f that is narrower than the edge sections 122e, 122e. Note that the dividing section 122f does not necessarily have to be provided.

[0086] As shown in Figures 6(a) to (c), the control portion 122a of the grid electrode 122 may be a fine mesh, a parallel arrangement of narrow linear conductors along the longitudinal direction, or a parallel arrangement of narrow linear conductors inclined in a direction intersecting the longitudinal direction, with fine gaps uniformly formed along the longitudinal and width directions.

[0087] The control unit 122a of the grid electrode 122 charges the surface of the photosensitive drum 11 by attaching charged particles such as ions generated by corona discharge caused by applying a high voltage to the discharge wires 121, 121 to the surface of the photosensitive drum 11 through gaps formed between mesh-like or narrow linear conductors, and controls the charging potential of the photosensitive drum 11 by the action of the electric field formed by the voltage applied to the control unit 122a.

[0088] 5, the connecting portions 122b, 122c of the grid electrode 122 have an even number (eight in the illustrated example) of thin, straight connecting pieces 122b', 122c' extending parallel to each other from both longitudinal ends of the control portion 122a through the boundary portion 122d toward their longitudinal tips. The connecting portions 122b, 122c are formed by connecting the tips of two adjacent connecting pieces 122b', 122c' in a loop shape as a pair. In the illustrated example, the connecting pieces 122b", 122c" located at both widthwise ends are curved inward in the widthwise direction from midway along the longitudinal direction.

[0089] As shown in FIG. 7(a), the connecting portions 122b, 122c of the grid electrode 122 may be formed by two connecting pieces 122b, 122b extending from both ends in the width direction toward the center of the tip in the longitudinal direction, with the tips of the two connecting pieces 122b, 122b joined in a U-shape and provided with openings 122g for engaging with locking claws (not shown). Alternatively, as shown in FIG. 7(b), the connecting portions 122b, 122c may be formed by a wide band extending toward the tip in the longitudinal direction and with elongated openings 122h, 122h for connection along the width direction at the tips.

[0090] However, it is desirable to use, as the connecting portions 122b, 122c of the grid electrode 122, an even number of connecting pieces 122b', 122c' arranged parallel to each other along the width direction, with the tips of the connecting pieces 122b', 122c' connected in a loop shape, as shown in FIG. 5, because this allows for a substantially uniform tension to be applied along the width direction of the grid electrode 122.

[0091] 5, the grid electrode 122 has a free shape that is flat when no tension is applied along the longitudinal direction. Therefore, when the tension is released or reduced, the grid electrode 122 returns to the free shape, that is, the flat shape, due to its own elastic restoring force.

[0092] 8, the charging device 12 includes a guide member 124, front and rear insulating blocks 125 and 126, and a mounting member 127. The guide member 124 is provided along the longitudinal direction on the surface of the shield case 120 opposite the photosensitive drum 11 (the lower surface in the figure). The front and rear insulating blocks 125 and 126 are respectively disposed at both ends of the shield case 120 along the longitudinal direction. The mounting member 127 is provided at the front end of the front insulating block 125, which is disposed on the front side of the image forming apparatus 1.

[0093] The guide member 124 is formed into a long, thin flat plate shape from synthetic resin or the like. Two guide protrusions 124a, 124b are provided on both ends along the longitudinal direction of the outer surface of the guide member 124 to guide the charging device 12 when it is attached to the image forming apparatus 1. Of the two guide protrusions 124a, 124b, the guide protrusion 124b located on the rear side of the image forming apparatus 1 is formed longer than the guide protrusion 124a located on the front side of the image forming apparatus 1.

[0094] The insulating blocks 125, 126 at the front and rear ends are made of a single or multiple insulating members made of synthetic resin. The insulating blocks 125, 126 are fixed to both longitudinal ends of the shielding case 120 by means of snap engagement or the like. Two discharge wires 121, 121 and a grid electrode 122 are stretched over the insulating blocks 125, 126 at the front and rear ends. One end of each discharge wire 121, 121 is fixed to one of the insulating blocks 125, 126 at the front and rear ends, and the other end is fixed to the other insulating block 125 with a required tension applied via an elastic member such as a coil spring.

[0095] 9 , the rear insulating block 126 is provided with a curved holding portion 126a that holds the rear end of the grid electrode 122 by deforming it into a curved shape that conforms to the surface shape of the photosensitive drum 11, and multiple locking claws 126b, 126b... that lock and secure the connecting portion 122c of the grid electrode 122. The front end of the rear insulating block 126 is also provided with a semi-cylindrical and rectangular tubular current-carrying portion 126c that incorporates multiple current-carrying electrodes (not shown) for respectively applying current to the shield case 120, the discharge wire 121, and the grid electrode 122. When the charging device 12 is attached to the image forming apparatus 1, the current-carrying portion 126c of the rear insulating block 126 is connected to electrodes on the image forming apparatus 1, thereby enabling current to flow through the shield case 120, the discharge wire 121, and the grid electrode 122.

[0096] The rear end insulating block 126 is provided with positioning pins 126d, 126d that protrude toward the rear side in the longitudinal direction at both ends in the width direction to position the rear end of the charging device 12 when the charging device 12 is attached to the image forming apparatus 1. As shown in Fig. 4, the positioning pins 126d, 126d of the rear end insulating block 126 are fitted into positioning holes 206a, 206b of a positioning portion 206 provided in a support portion 203 at the rear end of the image forming unit 200, thereby positioning the charging device 12.

[0097] 10 , the front insulating block 125 is provided with a curved holding portion 125a that holds the front end of the grid electrode 122 by deforming it into a curved shape that conforms to the surface shape of the photosensitive drum 11, and a tensioning member 60 that engages and stretches the connecting portion 122b of the grid electrode 122. The tensioning member 60 applies tension to the connecting portion 122b of the grid electrode 122 by displacing it outward with respect to the charging area of ​​the grid electrode 122. The tensioning member 60 is attached to the front insulating block 125 so as to be rotatable about a rotation axis that is disposed along the width direction W of the charging device 12.

[0098] 12, the holding portions 125a, 126a of the insulating blocks 125, 126 and the curved portions 207, 208 of the image forming unit 200 are arranged so as to protrude slightly toward the mating member relative to the tension position of the grid electrode 122. As a result, the shape and position of the grid electrode 122 are determined by the curved portions 207, 208 of the image forming unit 200.

[0099] 10, the front insulating block 125 is provided with an upright wall 125d having an insertion hole 125c through which the connecting portion 122b of the grid electrode 122 is inserted. Furthermore, the upright wall 125d of the insulating block 125 is provided with positioning pins 125e, 125e (see FIG. 8) extending along the width direction above the insertion hole 125c, so as to protrude toward the charging region of the photosensitive drum 11 along the longitudinal direction L. The positioning pins 125e, 125e of the front insulating block 125 are fitted into positioning holes 205a, 205b of a positioning portion 205 provided in a support portion 202 at the front end of the image forming unit 200, thereby positioning the charging device 12.

[0100] 11, the tension member 60 provided on the insulating block 125 at the front end is formed by pressing or bending a metal sheet made of stainless steel or the like, or by integral molding of synthetic resin. The tension member 60 includes a main body 601 having a rectangular front shape that is long horizontally along the width direction W of the charging device 12, a plurality of locking claws 602, 602... provided at the upper end of the main body 601 so as to protrude upward at required intervals, pivotal support portions 603, 603 bent perpendicularly from both ends of the main body 601 along the width direction, and a connecting portion 604 bent in the same direction as the pivotal support portions 603, 603 at the lower end of the main body 601 to connect one end of a coil spring 605 as an example of a biasing means.

[0101] As shown in FIG. 11(a), the locking claws 602, 602... of the tension member 60 are arranged such that the locking claws 602, 602 at both ends along the width direction are positioned close to the grid electrode 122 so that the distances from the connecting pieces 122b', 122b" of the connecting portion 122b of the grid electrode 122, which is arranged in a curved shape, are approximately equal.

[0102] Rotating shafts 603a, 603a are provided on the support portions 603, 603 of the tension member 60 so as to protrude toward both ends in the width direction. As shown in Fig. 12, the rotating shafts 603a, 603a of the tension member 60 are rotatably supported by support portions 125f provided inside the insulating block 125 at the front end.

[0103] As shown in Figure 12, one end of a coil spring 605 is connected to the connecting portion 604 of the tension member 60. The other end of the coil spring 605 is fixed inside the insulating block 125. As a result, the tension member 60 is biased in the counterclockwise direction in the figure. Tension is applied by the coil spring 605 to the grid electrode 122 that is engaged with the engaging claws 602, 602, ... of the tension member 60.

[0104] The mounting member 127 of the charging device 12 is a member for mounting the charging device 12 in a fixed state when the charging device 12 is mounted to the image forming apparatus 1. As shown in Fig. 12, a fixed arm 127a biased in a counterclockwise direction by a spring 127b is rotatably attached to the mounting member 127. The charging device 12 is released from its mounted state with respect to the image forming apparatus 1 by manually gripping a release lever (not shown) provided on the mounting member 127 to rotate the fixed arm 127a in a clockwise direction.

[0105] <Configuration of the cleaning device for the charging device> The charging device 12 according to the first embodiment includes a cleaning device 70 as an example of a cleaning means for cleaning at least the control electrode out of the discharge electrode and the control electrode. The cleaning device 70 according to the first embodiment cleans both the two discharge wires 121 and the grid electrode 122.

[0106] As shown in Figure 13, when charging is performed by the charging device 12, the cleaning device 70 waits in a standby position set at the end of the insulating block 126 at the rear end, which is one end along the longitudinal direction of the shield case 120 of the charging device 12.

[0107] 14 is a perspective view of the elongated charging device 12 equipped with the cleaning device 70, viewed from the front end to the rear end along the longitudinal direction. Note that FIG. 14 shows the state in which the grid electrode 122 is deformed into a flat shape during cleaning.

[0108] As shown in Fig. 15, the cleaning device 70 includes an upper body 71 and a lower body 72. The upper body 71 is formed in the shape of a rectangular frame with a downward-facing cross section and an open lower end face. The lower body 72 is formed in the shape of a rectangular frame with a downward-facing cross section and is lower in height than the upper body 71. The lower body 72 is provided integrally with the upper body 71 by being fitted onto the lower end of the upper body 71.

[0109] 14, the upper main body 71 has an upper end 710 that corresponds to the ceiling wall 120a of the shielding case 120, and left and right side surfaces 711, 712 that correspond to the left and right side surfaces 120b, 120c of the shielding case 120. The upper end 710 of the upper main body 71 is provided with guide ridges 710a at both ends along the width direction to guide the ceiling wall 120a of the shielding case 120. In addition, the left and right side surfaces 711, 712 of the upper main body 71 are provided with short guide ridges 711a, 712a at both ends along the lower longitudinal direction to guide the left and right side surfaces 120b, 120c of the shielding case 120, respectively.

[0110] As shown in Fig. 15, the upper end 710 of the upper main body 71 is provided with left and right support plate portions 714, 715 that protrude upward parallel to each other with a gap 713 interposed therebetween in the center along the width direction, and a cylindrical drive portion 716 that is arranged horizontally above the left and right support plate portions 714, 715. A spiral groove (not shown) that engages with the spiral protrusion 209a of the drive shaft 209 is formed inside the drive portion 716. The left and right support plate portions 714, 715 protrude above the top wall 120a of the shield case 120 through an air outlet 120e that is opened in the top wall 120a of the shield case 120, as shown in Fig. 14.

[0111] 15, left and right guide plate portions 717, 718 are provided on the outer surfaces of the left and right support plate portions 714, 715 of the upper main body 71 so as to protrude outward in the horizontal direction. The left and right guide plate portions 717, 718 are provided on the lower surfaces of their tips with guide ridges 717a, 718a, respectively, that guide the ceiling wall 120a of the shield case 120.

[0112] A swing arm 73 that holds the cleaning member is housed inside the upper main body 71. The swing arm 73 is attached to left and right side surface portions 711, 712 of the upper main body 71 via rotation shafts 731, 732 so as to be swingable.

[0113] 16 and 17, the swing arm 73 integrally includes left and right horizontal plate portions 733, 734, a connecting plate portion 735, and left and right mounting plate portions 736, 737. The left and right horizontal plate portions 733, 734 of the swing arm 73 are separated into left and right portions along the horizontal direction and arranged across the partition wall 120d of the shield case 120. Rotation shafts 731, 732 that swingably support the swing arm 73 are provided at the horizontal ends of the left and right horizontal plate portions 733, 734. As described above, the rotation shafts 731, 732 of the swing arm 73 are rotatably supported in insertion holes provided in the left and right side surface portions 711, 712 of the upper main body 71.

[0114] The connecting plate portion 735 of the swing arm 73 is configured as an elongated downward rectangular frame extending vertically upward from the central end along the width direction of the left and right horizontal plate portions 733, 734. As shown in Fig. 14 , the connecting plate portion 735 of the swing arm 73 connects the left and right horizontal plate portions 733, 734 while straddling the partition wall 120d of the shield case 120.

[0115] The mounting plate portions 736, 737 of the swing arm 73 are provided to extend horizontally from the central ends along the width direction of the left and right horizontal plate portions 733, 734. Cleaning pads 738, 739, which are an example of cleaning members that clean the two discharge wires 121 from above, are attached to the mounting plate portions 736, 737 of the swing arm 73. The cleaning pads 738, 739 are made of materials such as felt or sponge.

[0116] Actuating portions 736a and 737a are provided at opposing lower ends of connecting plate portion 735 of swing arm 73 so as to protrude downward. Swing arm 73 is wound around the outer peripheries of rotating shafts 731 and 732 and is biased counterclockwise by coil spring 740, which is integrally formed on the left and right sides by being suspended along the outer periphery of connecting plate portion 735. The tip of coil spring 740, which is wound around the outer peripheries of rotating shafts 731 and 732, abuts against a part of upper main body 71, thereby generating a biasing force in the counterclockwise direction. Therefore, during cleaning, swing arm 73 rotates counterclockwise due to the biasing force of coil spring 740, and cleaning pads 738 and 739 are pressed against a cleaning pad provided on lower main body 72, thereby cleaning two discharge wires 121 and 121.

[0117] 14, when the cleaning device 70 is in the standby position and not cleaning, the swing arm 73 is stopped in a clockwise rotated state as the actuating arm provided on the insulating block 126 at the rear end presses the actuating portions 736a, 737a provided on the lower ends of the mounting plates 736, 737. Therefore, the swing arm 73 is rotated clockwise against the biasing force of the coil spring 740, and the cleaning pads 738, 739 are separated from the two discharge wires 121. At this time, the cleaning pads provided on the lower main body 72 are also separated from the two discharge wires 121.

[0118] The lower body 72 has an upper end surface 720 that is positioned at the lower end of the upper body 71 and is wider than the upper body 71, and left and right side surfaces 721, 722 that extend downward from both ends of the upper end surface 720 along the width direction.

[0119] Left and right vertical plate portions 723, 724 are provided on the upper end surface 720 of the lower main body 72 near both ends in the width direction and protruding upward in the vertical direction. Two protrusions 725, 725 are provided on the outer surfaces of the left and right vertical plate portions 723, 724 of the lower main body 72 along the longitudinal direction for fitting and fixing to the upper main body 71. The protrusions 725, 725 of the left and right vertical plate portions 723, 724 are fitted and fixed in insertion holes provided in the left and right side surface portions 711, 712 of the upper main body 71 (see FIG. 15).

[0120] Cleaning pads 726, 727 are fixedly provided on the upper end surface 720 of the lower body 72 in positions facing the cleaning pads 738, 739 of the upper body 71. The cleaning pads 726, 727 of the lower body 72 are positioned slightly spaced apart from the two discharge wires 121. In addition, a wide cleaning pad 728 is provided on the underside of the upper end surface 720 of the lower body 72 for cleaning the grid electrode 122. The cleaning pad 728 is made of a material such as felt or sponge.

[0121] Support plates 729, 730 are provided on the inner surfaces of the lower ends of the left and right side surfaces 721, 722 of the lower main body 72, facing inward in the width direction and supporting both widthwise ends of the grid electrode 122 during cleaning. The upper end surfaces of the support plates 729, 730 are formed in a flat shape.

[0122] Incidentally, in the charging device 12 configured as described above, the grid electrode 122 is arranged in a curved arc shape that follows the surface shape of the photosensitive drum 11. Therefore, when the grid electrode 122 of the charging device 12 is cleaned by the cleaning pad 728 of the cleaning device 70, the grid electrode 122 is pressed by the cleaning pad 728 and comes into contact with the surface of the photosensitive drum 11, and it is difficult to bring the cleaning pad 728 into uniform contact with the entire surface of the grid electrode 122 that is arranged in a curved shape, resulting in technical problems such as reduced cleanability and uneven contamination of the grid electrode 122, which causes variations in the charging potential of the photosensitive drum 11.

[0123] Therefore, the charging device according to the first embodiment is configured to include a deformation means for deforming the shape of the control electrode into a shape different from that when the control electrode is being charged, during cleaning by the cleaning means.

[0124] Furthermore, in the charging device according to this embodiment 1, the control electrode is stretched with tension applied in a direction intersecting the direction of rotation of the body to be charged, and is held in a curved or bent shape by a holding member in accordance with the surface shape of the body to be charged.

[0125] Furthermore, the charging device according to the first embodiment is configured such that, during cleaning, the deformation means reduces the tension on the control electrode, thereby deforming the control electrode into a shape different from that during charging.

[0126] Furthermore, the charging device according to this embodiment 1 is configured so that at least one end of the control electrode along a direction intersecting the rotation direction of the body to be charged is urged outward toward the charging area of ​​the body to be charged by a tension member.

[0127] In addition, in the charging device according to this embodiment 1, the deformation means is configured to deform the control electrode into a shape different from that when it is charged by changing the position at which the tension member tensions the other end of the control electrode inward relative to the charging area of ​​the charged body along a direction intersecting the rotation direction of the charged body.

[0128] That is, as shown in FIG. 10, the charging device 12 according to this embodiment 1 includes a tensioning member 60 that constitutes part of a deformation means for applying tension to the connecting portion 122b located at one end of the grid electrode 122 along the longitudinal direction L.

[0129] 11(b), an eccentric cam 80 as an example of a deformation means is disposed on the tension member 60. The eccentric cam 80 is rotationally driven by rotating a small drive motor (not shown) provided in the charging device 12 or an operating lever (not shown) provided on the mounting member 127. The eccentric cam 80 may be configured so that a driving force is transmitted from the image forming unit 200. When the eccentric cam 80 is rotationally driven and the eccentric portion 81 abuts against the main body 601 of the tension member 60, the main body 601 rotates the tension member 60 clockwise around the rotation shaft 603a against the biasing force of the coil spring 605.

[0130] As a result, the grid electrode 122, which is engaged with the engagement claws 602, 602 of the tensioning member 60, is tensioned by the insulating block 125 at the front end, and the tension on the grid electrode 122 is shifted toward the charging region along the longitudinal direction L of the charging device 12, and the tension on the grid electrode 122 is released or reduced. As a result, the grid electrode 122 is deformed into a flat plate shape by its own elastic restoring force, as shown in FIG.

[0131] <Operation of the charging device> In the charging device according to this embodiment 1, it is possible to improve the cleanability of the control electrode while preventing the control electrode from coming into contact with the surface of the body to be charged, compared to when the control electrode is cleaned while maintaining the same shape as when it was charged, as follows.

[0132] In the image forming apparatus 1, as shown in FIG. 1, a cleaning operation is performed by the cleaning device 70 to clean the discharge wires 121, 121 and the grid electrode 122 of the charging device 12 at a predetermined timing depending on the cumulative image formation time of each imaging device 10 (Y, M, C, K) of yellow (Y), magenta (M), cyan (C) and black (K), the cumulative number of prints on the recording paper 5, etc.

[0133] In the charging device 12, during cleaning, prior to the cleaning operation by the cleaning device 70, an operation is performed to deform the shape of the grid electrode 122 into a flat plate shape, which is an example of a shape different from that during charging.

[0134] 18, the charging device 12 rotates the eccentric cam 80 in a clockwise direction by operating a drive motor or solenoid (not shown), or a release lever provided on the mounting member. Then, the main body 601 of the tension member 60 is pushed by the eccentric portion 81 of the eccentric cam 80, and the tension member 60 rotates a predetermined amount in a clockwise direction around the rotation shaft 603a.

[0135] 19, as the tension member 60 rotates, the multiple locking claws 602, 602... provided on the upper end of the tension member 60 move toward the charging region along the longitudinal direction of the charging device 12, thereby releasing or reducing the tension applied to the grid electrode 122. As a result, the grid electrode 122 returns to its original flat shape due to its own elastic restoring force.

[0136] Next, as shown in FIG. 13, the cleaning device 70 rotates the drive shaft 209, so that the drive part 716 of the cleaning device 70, which engages with the drive shaft 209, gradually moves along the longitudinal direction of the charging device 12 from the rear end insulating block 126 side toward the front end insulating block 125 side.

[0137] When the cleaning device 70 moves away from the insulating block 126 at the rear end, as shown in Figures 17(a) and (b), the pushing action of the operating arm 126e of the insulating block 126 at the rear end pushing the operating parts 736a, 737a of the oscillating arm 73 of the cleaning device 70 is released, the oscillating arm 73 rotates counterclockwise due to the biasing force of the coil spring 740, and the cleaning pads 738, 739 abut against the cleaning pads 726, 727 of the lower main body 72 while pressing the two discharge wires 121, 121 from above.

[0138] In this way, the two discharge wires 121, 121 of the charging device 12 are clamped by the cleaning pads 738, 739 and cleaning pads 726, 727 arranged above and below the cleaning device 70, and as the cleaning device 70 moves along the longitudinal direction L of the charging device 12, the two discharge wires 121, 121 are cleaned over their entire length.

[0139] As shown in FIG. 20 , the cleaning device 70 cleans the grid electrode 122 using a cleaning pad 728 provided on the lower main body 72. The lower surfaces (surfaces facing the photosensitive drum 11) of both widthwise ends of the grid electrode 122 are supported by the support plate portion of the lower main body 72. Because the grid electrode 122 is deformed into a flat shape, the cleaning pad 728 can be brought into contact with the entire surface of the grid electrode 122 for cleaning, compared to cleaning the grid electrode 122 in its curved shape. This improves the cleanability of the grid electrode 122 and allows for better cleaning. This prevents or suppresses a deterioration in the cleanability of the grid electrode 122, which in turn reduces the performance of the grid electrode 122 and causes uneven charging by the charging device 12.

[0140] When the cleaning device 70 moves to the insulating block 125 at the front end of the charging device 12 and completes the cleaning operation of the discharge wires 121, 121 and the grid electrode 122, it rotates the drive shaft 209 in the reverse direction to return to the standby position, thereby completing the series of cleaning operations. Note that the cleaning device 70 can effectively clean the discharge wires 121, 121 and the grid electrode 122 by moving back and forth multiple times along the longitudinal direction L of the charging device 12.

[0141] 21, the cleaning device 70 may be configured so that the grid electrode 122 is slightly curved downwardly convex rather than simply flat by devising the surface shape of the cleaning pad 728 provided on the lower main body 72 and the shapes of the support plates 729, 730 that support both ends of the grid electrode 122 along the width direction. In this case, the tension on the grid electrode 122 is released or reduced, so that the grid electrode 122 can be easily and reliably curved downwardly convexly.

[0142] When the cleaning device 70 moves to the standby position, the cleaning pads 738 and 739 and the cleaning pads 726 and 727 are separated from the two discharge wires 121 and 121 , and the cleaning pad 728 is separated from the grid electrode 122 .

[0143] Embodiment 2 22 is a structural diagram showing a charging device according to a second embodiment of the present invention. In the charging device according to the second embodiment, the deformation means changes the shape of the holding portion that holds the control electrode from a curved or bent shape to a flat shape.

[0144] In addition, in this embodiment 2, the deformation means has a holding member that holds one end of the control electrode along a direction that intersects with the rotation direction of the charged body, and the holding member is configured to have a curved portion that curves or bends the control electrode to fit the surface shape of the charged body when charging, and a flat portion that deforms the shape of the control electrode into a flat shape different from when it is charged when cleaning.

[0145] That is, in the charging device 12 according to the second embodiment, as shown in FIG. 22, a holding portion provided on the insulating block 125 at the front end for holding one end of the grid electrode 122 along the longitudinal direction L is configured as a holding member 130, which is an example of deformation means, as a separate member from the insulating block 125.

[0146] 23 , the holding member 130 is attached to the insulating block 125 so as to be rotatable about a rotation shaft 131 that is disposed along the width direction W of the grid electrode 122. The holding member 130 is rotationally driven by a drive motor or solenoid provided in the charging device 12, or by a pinion gear that meshes with a rack gear that is disposed along the longitudinal direction of the charging device 12 and that can be moved along the longitudinal direction by an operating unit provided on the mounting member 127.

[0147] The holding member 130 has a curved surface portion 132 provided on its upper end surface that corresponds to the curved shape of the grid electrode 122, and a flat surface portion 133 provided on the surface adjacent to the curved surface portion 132. The flat surface portion 133 of the holding member 130 is set to protrude from the surface of the insulating block 125 by the same amount as or smaller than the curved surface portion 132. When the holding member 130 is rotated around the rotation axis 131 and the flat surface portion 133 comes into contact with the grid electrode 122, the grid electrode 122 is deformed into a flat shape and held.

[0148] The holding member 130 may be provided only on the insulating block 125 at the front end, or may be provided on both the insulating blocks 125 and 126 at the front and rear ends.

[0149] In the charging device 12 according to the second embodiment, as shown in FIG. 24, during cleaning, the flat surface 133 of the holding member 130 is rotated to hold the grid electrode 122, thereby deforming the grid electrode 122 into a flat plate shape conforming to the flat surface 133 of the holding member 130.

[0150] Therefore, the cleaning device 70 for cleaning the charging device 12 can clean the grid electrode 122 evenly and satisfactorily by cleaning the grid electrode 122 that has been deformed into a flat plate shape.

[0151] The other configurations and operations are the same as those of the first embodiment, and therefore the description thereof will be omitted.

[0152] Embodiment 3 25 is a structural diagram showing a charging device according to embodiment 3 of the present invention. The charging device according to embodiment 3 is configured so that, during charging, the control electrode is pressed by a regulating member provided on the side of the body to be charged, thereby becoming curved along the surface shape of the body to be charged.

[0153] In addition, the charging device according to this embodiment 3 is configured such that the deformation means changes the position of the charging device in a direction away from the body to be charged, thereby deforming the shape of the control electrode into a shape different from that when it is charged.

[0154] 25, charging device 12 according to the third embodiment is provided with a retraction mechanism 300 as an example of deformation means. Charging device 12 is configured to be movable between a charging position close to photosensitive drum 11 and a cleaning position spaced apart from photosensitive drum 11 by retraction mechanism 300 equipped with guide rails 301.

[0155] Unlike the above-described embodiments, the charging device 12 has a grid electrode 122 stretched in a flat shape. However, the charging device 12 according to this third embodiment is not limited to a case in which the grid electrode 122 is stretched in a flat shape, and may also include a deformation means for deforming the grid electrode 122 from a curved shape to a flat shape, as in the first embodiment. In this case, the charging device 12 is configured to perform the next operation after deforming the grid electrode 122 from a curved shape to a flat shape.

[0156] During charging, the charging device 12 is located at a charging position close to the photosensitive drum 11 by a retraction mechanism. At this time, as shown in FIG. 25(b), the grid electrode 122 of the charging device 12 is pressed against curved portions 207 and 208 provided on the image forming unit 200, and is deformed into a curved shape that follows the surface shape of the photosensitive drum 11. Note that in FIG. 25(b), the width of the grid electrode 122 along the thickness direction is shown wide in order to show the grid electrode 122 deformed into a curved shape.

[0157] Meanwhile, during cleaning, the charging device 12 is moved by a retraction mechanism to a cleaning position away from the photosensitive drum 11. When the grid electrode 122 of the charging device 12 moves to the cleaning position, it moves away from the curved portions 207 and 208 of the image forming unit 200, and returns from its curved shape that follows the surface shape of the photosensitive drum 11 to its original flat shape.

[0158] Then, in the charging device 12, the discharge wire and the grid electrode 122 are cleaned by the cleaning device 70 while the grid electrode 122 is deformed into a flat shape.

[0159] In the charging device 12 according to the third embodiment, the free shape of the grid electrode 122 is a flat shape, and when charging, both ends of the grid electrode 122 along the longitudinal direction L are pressed against the curved portions 207, 208 of the image forming unit 200, thereby forming a curved shape.

[0160] However, the charging device 12 according to the third embodiment is not limited to this. The grid electrode 122 may be arranged in a curved shape on the charging device 12, and during cleaning, for example, a pressing member (not shown) with a flat tip provided on the image forming unit 200 side may be pressed against the grid electrode 122 to deform the grid electrode 122 into a flat shape.

[0161] Further, the charging device 12 may be configured to be separated from the photosensitive drum 11 either before or after the grid electrode 122 is deformed.

[0162] The other configurations and operations are the same as those of the first embodiment, and therefore the description thereof will be omitted.

[0163] Embodiment 4 26 is a structural diagram showing a charging device according to a fourth embodiment of the present invention. In the charging device according to the fourth embodiment, the control electrode is configured to have a bent shape rather than a curved shape that follows the surface shape of the body to be charged.

[0164] That is, in the charging device 12 according to the fourth embodiment, the grid electrode 122 is arranged in a shape that is bent in a substantially V-shape or the like along the surface shape of the photosensitive drum 11, as shown in FIG.

[0165] The grid electrode 122 may be a flat plate bent into a substantially V-shape, or a plurality of flat grid electrodes 122 may be combined to form a bent shape that conforms to the surface shape of the photosensitive drum 11. The grid electrode 122 is not limited to a shape bent into a substantially V-shape, and may be arranged in a polyhedral shape, for example, when the charging device 12 has three discharge wires 121, as shown in FIG.

[0166] As shown in FIG. 28, the holding portions 125a, 126a of the insulating blocks 125, 126 that hold the grid electrode 122 are not curved to match the shape of the grid electrode 122, but are bent in an inverted V shape or the like.

[0167] When the grid electrode 122 is configured by combining two flat grid electrodes 122, as shown in FIG. 28, the lower body 72 that holds the grid electrodes 122 of the cleaning device 70 is configured to hold the two grid electrodes 122 in a flat plate shape.

[0168] That is, when the cleaning device 70 moves from the connecting portion 122c located at one end of the grid electrode 122 to the connecting portion 122b during cleaning, the two grid electrodes 122 arranged in a V-shape are deformed into a flat shape by having both ends along the width direction W held by the flat holder member 150 of the cleaning device 70.

[0169] FIG. 29 is a structural diagram showing a modified example of the charging device according to the fourth embodiment.

[0170] In a modified example of the charging device 12 according to the fourth embodiment, as shown in FIG. 29, a tension member that tensions both longitudinal ends of the two grid electrodes 122, 122 is configured to be able to open and close like a hinge via a central shaft disposed between the two grid electrodes 122.

[0171] As shown in FIG. 29, during cleaning, the charging device 12 rotates the tensioning member so that the two grid electrodes 122 are tensioned in a flat plate shape, thereby deforming the two grid electrodes 122 into a flat plate shape, which can then be cleaned by the cleaning device 70.

[0172] FIG. 30 is a structural diagram showing a further modified example of the charging device according to the fourth embodiment.

[0173] In this modified example of the charging device 12, as shown in FIG. 30, similar to the second embodiment, the tensioning member 60 that suspends the two grid electrodes 122 in a V-shape includes a V-shaped curved portion 132 and a flat portion 133.

[0174] In this modified example of the charging device 12, during cleaning, the flat portion 133 of the tension member 60 is rotated so as to come into contact with the two grid electrodes 122, thereby deforming the two grid electrodes 122 into a flat plate shape.

[0175] The other configurations and operations are the same as those of the first embodiment, and therefore the description thereof will be omitted.

[0176] In the above embodiment, a full-color image forming apparatus has been described, but it goes without saying that the present invention can also be applied to a monochrome image forming apparatus.

[0177] Furthermore, in the above embodiment, the case where the number of discharge wires 121 is two has been described, but the number of discharge wires 121 is not limited to two, and one or three or more may be provided.

[0178] (Addendum) (((1))) A discharge electrode; a control electrode disposed between the discharge electrode and a body to be charged by the discharge electrode, the control electrode being curved or bent along the surface shape of the body to be charged; a cleaning means for cleaning at least the control electrode out of the discharge electrode and the control electrode; a deformation means for deforming the shape of the control electrode into different shapes when the control electrode is cleaned by the cleaning means and when the control electrode is charged; A charging device comprising: (((2))) The control electrode is stretched with tension applied in a direction intersecting the direction of rotation of the body to be charged, and is held in a curved or bent shape along the surface shape of the body to be charged by a holding member (((1))). (((3))) The charging device according to (((2))), wherein the deformation means deforms the control electrode into a shape different from that during charging by reducing tension on the control electrode during cleaning. (((4))) The charging device described in (((1))) has at least one end of the control electrode along a direction intersecting the rotation direction of the body to be charged, which is urged outward toward the charging area of ​​the body to be charged by a tension member. (((5))) The deformation means changes the position at which the tension member tensions the other end of the control electrode inward with respect to the charging area of ​​the charged body along a direction intersecting the rotation direction of the charged body, thereby deforming the control electrode into a shape different from that when charged. (((4))) (((6))) The charging device according to (((1))), wherein the deformation means changes the shape of a holding portion that holds the control electrode from a curved or bent shape to a flat shape. (((7))) The deformation means has a holding member that holds one end of the control electrode along a direction that intersects with the rotation direction of the body to be charged, and the holding member has a curved portion that curves or bends the control electrode to follow the surface shape of the body to be charged when charging, and a flat portion that deforms the shape of the control electrode to a flat shape different from that when charging when cleaning. (((6))) (((8))) The charging device described in (((1))) above, wherein the control electrode is pressed against a regulating member provided on the body to be charged during charging, thereby taking on a curved shape that conforms to the surface shape of the body to be charged. (((9))) The charging device according to (((8))), wherein the deformation means changes the position of the charging device in a direction away from the body to be charged, thereby deforming the shape of the control electrode into a shape different from that when the control electrode is charged. (((10))) The charging device described in (((1))) above, wherein the deformation means deforms the shape of the control electrode to a shape different from that when charged, and further changes the position of the charging device in a direction away from the body to be charged. (((11))) The deforming means deforms the shape of the control electrode into a shape different from that when the control electrode is charged by pressing both ends of the control electrode along a direction intersecting the rotation direction of the charged body (((1))). (((12))) The charging device according to (((11))), wherein the deformation means has a pressing member that presses both ends of the control electrode along a direction intersecting the rotation direction of the charged body, and the pressing member has a pressing portion that deforms the control electrode into a planar shape. (((13))) The charging device according to (((1))), wherein the cleaning means cleans both the discharge electrode and the control electrode. (((14))) The cleaning means has a first cleaning member that contacts the discharge electrode and a second cleaning member that contacts both the front and back surfaces of the control electrode that has been deformed into a shape different from that when charged. (((13))) The charging device described in (((15))) A charging device according to any one of (((1))) to (((14))), An image forming unit that is detachably attached to an image forming apparatus. (((16))) Image holding means; a charging means for charging the surface of the image holding means; an electrostatic latent image forming means for forming an electrostatic latent image on the surface of the image holding means charged by the charging means; Equipped with An image forming apparatus using the charging device according to any one of ((1))) to (((14))) as the charging means.

[0179] According to the charging device of (((1))), the cleaning ability of the control electrode can be improved while preventing the control electrode from coming into contact with the surface of the body to be charged, compared to when the control electrode is cleaned while maintaining the same shape as when it was charged. According to the charging device of (((2))), the control electrode can be a flat control electrode, compared to when the control electrode is formed in a curved or bent shape that follows the surface shape of the body to be charged without using a holding member. According to the charging device of (((3))), the deformation means can easily deform the control electrode into a shape different from the shape when charged by simply reducing the tension during cleaning, compared to when an external force is applied to the control electrode to deform it into a shape different from the shape when charged. According to the charging device of (((4))), the control electrode can simplify the structure for urging the control electrode outward with respect to the charging area of ​​the body to be charged, compared to when no tension member is used. According to the charging device of (((5))), the deformation means simplifies the structure of the tension member compared to when the tension member changes the positions of both ends of the control electrode. According to the charging device of (((6))), the deformation means can be configured more easily than when the shape of the deformation means is changed other than the shape of the holding portion that holds the control electrode. According to the charging device of (((7))), the deformation means can deform the shape of the control electrode using a single holding member, compared to when the curved portion and the flat portion are provided on different holding members. According to the charging device of (((8))), the control electrode can be easily bent or curved during charging, compared to when the control electrode is curved or curved by regulating members provided on both the charging device and the charged body side. According to the charging device of (((9))), the deformation means can easily change the shape of the control electrode by simply changing the position of the charging means, compared to when the tension of the control electrode is changed. According to the invention described in the charging device of (((10))), it is possible to clean both the front and back sides of the control electrode in accordance with the surface shape of the body to be charged while preventing the cleaning means from coming into contact with the surface of the body to be charged. According to the charging device of (((11))), the deformation means can more reliably deform the shape of the control electrode than when the tension of the control electrode is changed. According to the charging device of (((12))), the deformation means is a member that presses both ends of the control electrode along the longitudinal direction, and can reliably deform the control electrode into a planar shape compared to a case in which there is no pressing member that has a pressing portion that deforms the control electrode into a planar shape. According to the charging device of (((13))), the structure of the cleaning means can be simplified compared to when the cleaning means cleans only the control electrode. According to the charging device of (((14))), the cleaning means is able to clean both the discharge electrode and the control electrode, compared to a case where the cleaning means does not have a first cleaning member that contacts the discharge electrode and a second cleaning member that contacts both the front and back surfaces of the control electrode that has been deformed into a shape different from that when charged. With the image forming unit according to (((15))), it is possible to clean both the front and back sides of the control electrode that is curved along the surface shape of the body to be charged while preventing the cleaning means from coming into contact with the surface of the body to be charged, compared to when the image forming unit does not have a charging device described in any of (((1))) to (((14))). According to the image forming apparatus of (((16))), it is possible to clean both the front and back sides of the control electrode curved along the surface shape of the body to be charged while preventing the cleaning means from coming into contact with the surface of the body to be charged, compared to when the charging device described in any of (((1))) to (((14))) is not used as the charging means. [Explanation of symbols]

[0180] 1...Image forming device 12...Charging device 120...Shield case 121...Discharge wire 122...Grid electrode 125, 126...insulating block 60...Tension member

Claims

1. A discharge electrode; a control electrode disposed between the discharge electrode and a body to be charged by the discharge electrode, the control electrode being curved or bent along the surface shape of the body to be charged; a cleaning means for cleaning at least the control electrode out of the discharge electrode and the control electrode; a deformation means for deforming the shape of the control electrode into different shapes when the control electrode is cleaned by the cleaning means and when the control electrode is charged; A charging device comprising:

2. 2. The charging device according to claim 1, wherein the control electrode is stretched with tension applied in a direction intersecting the direction of rotation of the body to be charged, and is held in a curved or bent shape that conforms to the surface shape of the body to be charged by a holding member.

3. 3. The charging device according to claim 2, wherein the deformation means deforms the control electrode into a shape different from that during charging by reducing tension of the control electrode during cleaning.

4. 2. The charging device according to claim 1, wherein at least one end of the control electrode along a direction intersecting the direction of rotation of the body to be charged is biased outwardly by a tension member toward the charging region of the body to be charged.

5. 5. The charging device according to claim 4, wherein the deformation means changes the position at which the tension member tensions the other end of the control electrode inward with respect to the charging area of ​​the body along a direction intersecting the rotation direction of the body, thereby deforming the control electrode into a shape different from that when it is charged.

6. 2. The charging device according to claim 1, wherein the deformation means changes the shape of a holding portion that holds the control electrode from a curved or bent shape to a flat shape.

7. 7. The charging device according to claim 6, wherein the deformation means has a holding member that holds one end of the control electrode along a direction intersecting the rotation direction of the body to be charged, and the holding member has a curved portion that curves or bends the control electrode to conform to the surface shape of the body to be charged when charging, and a flat portion that deforms the shape of the control electrode into a flat shape different from that when charging when cleaning.

8. 2. The charging device according to claim 1, wherein the control electrode is pressed by a regulating member provided on the member to be charged during charging, so that the control electrode assumes a curved shape that conforms to the surface shape of the member to be charged.

9. 9. The charging device according to claim 8, wherein the deformation means changes the position of the charging device in a direction away from the member to be charged, thereby deforming the control electrode into a shape different from that when the control electrode is charged.

10. 2. The charging device according to claim 1, wherein the deformation means deforms the control electrode into a shape different from that when the control electrode is charged, and further changes the position of the charging device in a direction away from the member to be charged.

11. 2. The charging device according to claim 1, wherein the deformation means deforms the shape of the control electrode into a shape different from that when the control electrode is charged by pressing both end portions of the control electrode along a direction intersecting the direction of rotation of the member to be charged.

12. 12. The charging device according to claim 11, wherein the deformation means has a pressing member that presses both end portions of the control electrode along a direction intersecting a rotation direction of the body to be charged, and the pressing member has a pressing portion that deforms the control electrode into a planar shape.

13. 2. The charging device according to claim 1, wherein said cleaning means cleans both said discharge electrode and said control electrode.

14. 14. The charging device according to claim 13, wherein the cleaning means comprises a first cleaning member that contacts the discharge electrode, and a second cleaning member that contacts both the front and rear surfaces of the control electrode that has been deformed into a shape different from that when the control electrode is charged.

15. A charging device according to any one of claims 1 to 14, An image forming unit that is detachably attached to an image forming apparatus.

16. Image holding means; a charging means for charging the surface of the image holding means; an electrostatic latent image forming means for forming an electrostatic latent image on the surface of the image holding means charged by the charging means; Equipped with An image forming apparatus using the charging device according to any one of claims 1 to 14 as the charging means.

Images