Charging device and image forming apparatus

Abstract

A charging device and an image forming apparatus, the charging device including: a discharge electrode; and a control electrode disposed between the discharge electrode and a member to be charged, the control electrode being held in a state of being curved along a surface shape of the member to be charged, and being pressed in a short side direction of the control electrode at a plurality of positions to a side away from the member to be charged, and in the plurality of positions where the control electrode is pressed, a central side in the short side direction protrudes more to the side away from the member to be charged than end sides.

Description

Technical Field

[0001] This invention relates to a charging device and an image forming apparatus. Background Technology

[0002] In existing electrophotographic image forming apparatuses, the technology for charging the surface of the image holder to be charged is known in the following patent documents 1 and 2.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2018-159793 discloses a technology in which the electrode component 40 of a charging unit 60 is bent by two contact members 53 and 54 at the axially upward end of a photoreceptor 30. The first contact member 53 is disposed on the outer side in the axial direction and is formed into a quadrilateral plate shape. The second contact member 54 is disposed on the inner side in the axial direction and is formed into a triangular plate shape. In Patent Document 1, the two corners of the quadrilateral plate-shaped first contact member 53 contact the electrode component 40 on the outer side in the axial direction, and the pointed corner of the triangular plate-shaped second contact member 54 contacts the electrode component 40 on the inner side in the axial direction, thereby deforming the electrode component 40 into a bent shape.

[0004] Patent Document 2: Japanese Patent Application Publication No. 2021-056456 discloses a structure in which two grid electrodes 53 of the charging device 214 are arranged with a partition plate 66 between them. In the rotation direction of the photosensitive drum 213, the grid electrode 53 located upstream of the partition plate 66 is arranged to tilt away from the photosensitive drum 213 as it moves downstream. The grid electrode 53 located downstream of the partition plate 66 is arranged to tilt closer to the photosensitive drum 213 as it moves downstream.

[0005] Patent Document 1: Japanese Patent Application Publication No. 2018-159793 (“0035”~“0087”) Figures 2-6 )

[0006] Patent Document 2: Japanese Patent Application Publication No. 2021-056456 (“0054”~“0099”) Figures 4-7 ) Summary of the Invention

[0007] The technical challenge of this invention is to suppress the bending deviation of the control electrode in the long side direction, compared to the case where the end of the control electrode in the long side direction abuts against a contact portion of a shape corresponding to the curvature of the charged member, causing the control electrode to bend according to the curvature of the charged member.

[0008] To solve the aforementioned technical problem, the invention described in Solution 1 is a charging device, which comprises:

[0009] Discharge electrodes; and

[0010] A control electrode is disposed between the discharge electrode and the charged component.

[0011] The control electrode is held in a curved state along the surface shape of the charged member, and is pressed away from the charged member at multiple locations along the short side direction of the control electrode, and at the multiple locations where the control electrode is pressed, the central side in the short side direction protrudes further away from the charged member than the end side.

[0012] To address the aforementioned technical problem, the invention described in Solution 2 is a charging device, which comprises:

[0013] Discharge electrodes; and

[0014] A control electrode is disposed between the discharge electrode and the charged component.

[0015] The control electrode is held in a curved state along the surface shape of the charged member, and there is at least one part along the short side direction of the control electrode that is not pressed away from the side of the charged member, and in the multiple locations where the control electrode is pressed, the central side in the short side direction protrudes further away from the charged member than the end side.

[0016] To solve the aforementioned technical problem, the inventive charging device described in Solution 3 comprises:

[0017] Discharge electrodes; and

[0018] A control electrode is disposed between the discharge electrode and the charged component, and charges are drawn from the discharge electrode toward the charged component.

[0019] The control electrode is held in a bent state along the surface shape of the charged member, and is pressed at multiple locations away from the charged member along the short side direction of the control electrode, and at the multiple locations where the control electrode is pressed, the pressing force is stronger at the center side in the short side direction than at the end side.

[0020] The invention described in Scheme 4, in the charging device described in any of Schemes 1 to 3, includes a bending member.

[0021] The bending member is supported by the frame of the charging device and bends by pressing the control electrode away from the member being charged.

[0022] The curved member has a plurality of contact portions extending away from the charged member along the short side direction of the control electrode. Regarding the length of each contact portion, the contact portion on the central side in the short side direction is longer than the contact portion on the end side relative to the surface shape of the charged member.

[0023] The invention described in Scheme 5, in the charging device described in any of Schemes 1 to 3, includes a bending member.

[0024] The bending member is supported by the frame of the charging device and bends by pressing the control electrode away from the member being charged.

[0025] The bending member has multiple contact portions with curvature along the short side direction of the control electrode, and the curvature of each contact portion is larger on the central side than on the end side in the short side direction.

[0026] The invention described in Scheme 6, in the charging device described in Scheme 4 or 5, comprises:

[0027] The control electrode has a frame portion disposed along the outer periphery of the control electrode and a mesh portion disposed inside the frame portion; and

[0028] The curved member contacts the frame portion.

[0029] To solve the aforementioned technical problem, the invention described in Solution 7 is an image forming apparatus, comprising:

[0030] The charged component is composed of an image holding component;

[0031] The charging device described in any of Schemes 1 to 6 energizes the image holding member;

[0032] A latent image forming member forms a latent image on the image holding member;

[0033] The developing member develops the latent image of the image holding member;

[0034] A transfer component that transfers the image developed by the developing component onto a media; and

[0035] A fixing component fixes the image of the medium.

[0036] The invention described in embodiment 8, in the image forming apparatus described in embodiment 7, includes a bending member.

[0037] The bending member is disposed on the charged member and presses the control electrode away from the charged member to bend it.

[0038] The curved member has a plurality of contact portions extending away from the charged member along the short side direction of the control electrode. Regarding the length of each contact portion, the contact portion on the central side in the short side direction is longer than the contact portion on the end side relative to the surface shape of the charged member.

[0039] The invention described in embodiment 9, in the image forming apparatus described in embodiment 7, includes a bending member.

[0040] The bending member is disposed on the charged member and presses the control electrode away from the charged member to bend it.

[0041] The bending member has multiple contact portions with curvature along the short side direction of the control electrode, and the curvature of each contact portion is larger on the central side than on the end side in the short side direction.

[0042] The invention described in claim 10, in the image forming apparatus described in claim 8 or 9, comprises:

[0043] The control electrode has a frame portion disposed along the outer periphery of the control electrode and a mesh portion disposed inside the frame portion; and

[0044] The curved member contacts the frame portion.

[0045] Invention Effects

[0046] According to embodiments 1 to 3 and 7 of the present invention, compared to the case where the end of the control electrode in the long side direction abuts against a contact portion of a shape corresponding to the curvature of the charged member, causing the control electrode to bend according to the curvature of the charged member, the bending deviation of the control electrode in the long side direction can be suppressed.

[0047] According to embodiments 4 and 8 of the present invention, the tension of the control electrode can be made stronger in the central part than at the end by changing the length of the contact portion.

[0048] According to embodiments 5 and 9 of the present invention, the tension of the control electrode can be made stronger in the central part than at the end by pressing the control electrode with multiple contact portions of different curvatures.

[0049] According to the sixth and tenth embodiments of the present invention, compared with the case of contact with the mesh, the control electrode is less likely to be damaged and the force is easier to transmit. Attached Figure Description

[0050] The embodiments of the present invention will be described in detail with reference to the following figures.

[0051] Figure 1 This is an overall explanatory diagram of the image forming apparatus according to Embodiment 1 of the present invention;

[0052] Figure 2 This is an explanatory diagram of a visible image forming apparatus having an image holding unit and a developer;

[0053] Figure 3 This is a perspective view of the charger according to Embodiment 1 of the present invention;

[0054] Figure 4 This is a cross-sectional diagram illustrating the main parts of the charger according to Embodiment 1 of the present invention;

[0055] Figure 5 This is an explanatory diagram of the grid electrode in Example 1;

[0056] Figure 6 This is an illustration of the main components of a charger in the state of tensioned grid electrodes;

[0057] Figure 7 This is an explanatory diagram of the abutment member in Embodiment 1;

[0058] Figure 8 This is an explanatory diagram of the tension member in Example 1. Figure 8 (A) is a 3D diagram. Figure 8 (B) is from Figure 8 The diagram showing the direction of arrow VIIIB in (A);

[0059] Figure 9 This is an enlarged illustration of the bending member in Example 1;

[0060] Figure 10 This is an illustrative diagram of an experimental example with a small photosensitive drum diameter;

[0061] Figure 11 This is an illustrative diagram illustrating an experimental example with a large diameter photosensitive drum;

[0062] Figure 12 This is an explanatory diagram of the abutment member in Embodiment 2, which is the same as that in Embodiment 1. Figure 9 The corresponding diagram.

[0063] Symbol Explanation

[0064] 3, 4 - Frame of charging device; 11 - Discharge electrode; 12 - Control electrode; 13 - Mesh part; 13b, 13c - Frame part; 43, 74, 43', 74' - Bending member; 43a, 43a' - Contact part; CCy, CCm, CCc, CCk - Charging device; F - Fixing device; GY, GM, GC, GK - Developing member; Py, Pm, Pc, Pk - Charged member, image holding member; ROSy, ROSm, ROSc, ROSk - Latent image forming member; S - Media; T1+B+T2+CLB - Transfer member; U - Image forming device. Detailed Implementation

[0065] Next, with reference to the accompanying drawings, specific examples of embodiments of the present invention (hereinafter referred to as embodiments) will be described, but the present invention is not limited to the following embodiments.

[0066] In addition, to facilitate understanding of the following explanation, in the attached diagram, the front-back direction is set as the X-axis direction, the left-right direction is set as the Y-axis direction, and the up-down direction is set as the Z-axis direction. The directions or sides represented by the arrows X, -X, Y, -Y, Z, and -Z are respectively set as front, back, right, left, top, bottom, or front side, back side, right side, left side, top side, and bottom side.

[0067] Furthermore, in the diagram, the "·" mark in the "○" indicates an arrow pointing from the back of the paper to the front, and the "×" mark in the "○" indicates an arrow pointing from the front of the paper to the back.

[0068] In addition, in the description using the following figures, for ease of understanding, illustrations other than those of the parts required for the description have been appropriately omitted.

[0069] [Example 1]

[0070] Figure 1 This is an overall explanatory diagram of the image forming apparatus according to Embodiment 1 of the present invention.

[0071] exist Figure 1 In this device, the image forming apparatus U includes, for example, a user interface UI as an operation component, an image input device U1 as an image reading component, a paper feeding device U2 as a media supply component, an image recording device U3 as the main body of the image forming apparatus, and a paper handling device U4 as a post-processing component.

[0072] The user interface (UI) includes, for example, a copy start key, number keys, and a display UI1.

[0073] The image input device U1 is composed of an image scanner, such as an image reading device. Figure 1 In the image input device U1, the original document (not shown) is read, converted into image information, and input to the image recording device U3.

[0074] The paper feeding device U2 includes paper feed trays TR1, TR2, TR3, and TR4, which are examples of containers for multiple media, and a paper feed path SH1, which is an example of a recording paper S contained in each of the paper feed trays TR1 to TR4.

[0075] exist Figure 1 In this embodiment, the image recording device U3 includes an image recording unit that records images of the recording paper S conveyed from the paper feeding device U2, a toner dispensing device U3a, and paper conveying path SH2, paper discharge path SH3, paper reversal path SH4, and paper circulation path SH6. The image recording unit will be described later.

[0076] Furthermore, the image recording device U3 includes a control unit C as an example of a control component, a laser drive circuit D as an example of a drive circuit for a latent image writing device controlled by the control unit C, and a power supply circuit E controlled by the control unit C. The laser drive circuit D outputs laser drive signals corresponding to the image information Y (yellow), M (magenta), C (cyan), and K (black) input from the image input device U1 at predetermined times to the latent image forming devices ROSy, ROSm, ROSc, and ROSk for each color.

[0077] Below the latent image forming apparatus ROSy~ROSk, which is an example of a latent image forming component, the image forming unit is supported by a pair of left and right guide members R1, R1 by the extraction member U3b, so that it can move between an extraction position in front of the image recording apparatus U3 and an installation position inside the image recording apparatus U3.

[0078] Figure 2 This is an explanatory diagram of a visible image forming apparatus having an image holder unit and a developer.

[0079] exist Figure 1 , Figure 2 In this embodiment, the black image holding unit UK includes a photosensitive drum Pk as an example of an image holding member, a charger CCk as an example of a charging device and a charging member, and a photosensitive cleaner CLk as an example of a cleaning member of the image holding member. Furthermore, in Embodiment 1, the charger CCk is composed of a charging unit that can be attached to and detached from the image recording device U3. Additionally, the image holding units UY, UM, and UC of other colors Y, M, and C also include photosensitive drums Py, Pm, and Pc, chargers CCy, CCm, and CCc, and photosensitive cleaners CLy, CLm, and CLc. Furthermore, in Embodiment 1, the K-colored photosensitive drum Pk, which is used frequently and experiences significant surface wear, is configured with a larger diameter than the photosensitive drums Py, Pm, and Pc of other colors, achieving high-speed rotation countermeasures and a longer lifespan.

[0080] The image holding units UY, UM, UC, UK and the developers GY, GM, GC, GK with developing rollers R0 constitute the toner image forming components UY+GY, UM+GM, UC+GC, UK+GK. The image holding units UY, UM, UC, UK and the developers GY, GM, GC, GK are detachably mounted on the image forming unit extraction component U3b.

[0081] exist Figure 1In this process, after the photosensitive drums Py to Pk are charged by chargers CCy to CCk respectively, laser beams Ly, Lm, Lc, and Lk, which serve as examples of latent image writing light, are output by the latent image forming apparatus ROSy to ROSk to form an electrostatic latent image on their surface. The electrostatic latent image on the surface of the photosensitive drums Py to Pk is developed by the developers GY to GK, which serve as examples of developing components, into a toner image with Y: yellow, M: magenta, C: cyan, and K: black.

[0082] The toner image on the surface of the photosensitive drums Py to Pk is sequentially transferred by primary transfer rollers T1y, T1m, T1c, and T1k, which serve as a primary transfer component, onto an intermediate transfer belt B, which serves as an image holding component and an intermediate transfer body. A multicolor image (so-called a color image) is formed on the intermediate transfer belt B. The color image formed on the intermediate transfer belt B is then transferred to the secondary transfer area Q4.

[0083] In addition, when only black image data is available, only the black photosensitive drum Pk and the developer GK are used to form a black toner image.

[0084] After one transfer, the residual toner on the surface of the photosensitive drums Py to Pk is cleaned by the photosensitive cleaners CLy to CLk.

[0085] Below the image forming unit extraction member U3b, the intermediate transfer body extraction member U3c is supported so that it can move between an extraction position in front of the image recording device U3 and an installation position inside the image recording device U3. In the intermediate transfer body extraction member U3c, a tape module BM, as an example of an intermediate transfer member, is supported so that it can move up and down between an elevated position contacting the lower surface of the photosensitive drums Py to Pk and a lowered position spaced apart from the lower surface.

[0086] The belt module BM includes the intermediate transfer belt B, a belt drive roller Rd (an example of a drive member), a tension roller Rt (an example of a tension member), a floating roller Rw (an example of an anti-deviation member), multiple idler rollers Rf (an example of a driven member), a support roller T2a (an example of an opposing member for the secondary transfer area Q4), and primary transfer rollers T1y to T1k. Furthermore, the intermediate transfer belt B is supported by the belt support rollers Rd, Rt, Rw, Rf, and T2a, enabling it to rotate and move in the direction of arrow Ya.

[0087] A secondary transfer unit Ut is disposed below the support roller T2a. The secondary transfer unit Ut has a secondary transfer roller T2b, which is an example of a secondary transfer component. The secondary transfer roller T2b is configured to separate from and contact the support roller T2a through the intermediate transfer belt B, and the area in contact between the secondary transfer roller T2b and the intermediate transfer belt B forms the secondary transfer area Q4. Furthermore, a contact roller T2c, which is an example of a voltage application component, contacts the support roller T2a, and the rollers T2a to T2c constitute a secondary transfer device T2, which is an example of a secondary transfer component.

[0088] At a predetermined time, a secondary transfer voltage with the same polarity as the toner's charge polarity is applied to the contact roller T2c from the power circuit E controlled by the control unit C.

[0089] Below the module BM, a paper transport path SH2 is arranged. The recording paper S supplied from the paper supply path SH1 of the paper supply device U2 is transported to the paper transport path SH2, and is aligned with the toner image by the registration roller Rr, which is an example of a paper supply timing adjustment member, and is then transported to the secondary transfer area Q4 by the media guide members SGr and SG1 before transfer.

[0090] The toner image on the intermediate transfer belt B is transferred to the recording paper S by the secondary transfer unit T2 when passing through the secondary transfer area Q4. Alternatively, in the case of a full-color image, the toner image that is superimposed and transferred once to the surface of the intermediate transfer belt B is transferred twice to the recording paper S in a single operation.

[0091] The intermediate transfer belt B after the secondary transfer is cleaned (i.e., washed) by a belt cleaner CLB, which is an example of a cleaning member for intermediate transfer bodies.

[0092] The transfer device (an example of a transfer component) T1+B+T2+CLB consists of the primary transfer rollers T1y to T1k, the intermediate transfer belt B, the secondary transfer unit T2, and the belt cleaner CLB, which transfer the image on the surface of the photosensitive drums Py to Pk onto the recording paper S.

[0093] The recording paper S, which has been transferred with a toner image, is conveyed to the fixing device F via the media guide SG2 after transfer and the paper conveyor belt BH, which is an example of a media conveyor before fixing. The fixing device F, as an example of a fixing component, has a heating roller Fh, which is an example of a heating fixing component, and a pressure roller Fp, which is an example of a pressure fixing component. The area where the heating roller Fh contacts the pressure roller Fp forms the fixing area Q5.

[0094] The toner image on the recording paper S is heated and fixed by the fixing device F as it passes through the fixing area Q5.

[0095] The image recording unit of Embodiment 1, which records images on recording paper S, is composed of the toner image forming components UY+GY, UM+GM, UC+GC, UK+GK, the transfer device T1+B+T2+CLB, the fixing device F, etc.

[0096] Downstream of the fixing device F, a first gate GT1 is provided as an example of a conveying path switching member. The first gate GT1 selectively switches the recording paper S, which is conveyed on the paper conveying path SH2 and heated and fixed in the fixing area Q5, to either the paper discharge path SH3 or the paper reversal path SH4 of the image recording device U3. The recording paper S conveyed to the paper discharge path SH3 is then conveyed to the paper conveying path SH5 of the paper handling device U4.

[0097] A curling correction device U4a, serving as an example of a bend correction member, is disposed midway along the paper transport path SH5. A second gate G4, serving as an example of a transport path switching member, is also disposed along the paper transport path SH5. The second gate G4 conveys the recording paper S, which is transported from the paper discharge path SH3 of the image recording device U3, to either the first curling correction member h1 or the second curling correction member h2 according to the bend (so-called curling) direction. The recording paper S conveyed to the first curling correction member h1 or the second curling correction member h2 is corrected for curling as it passes through. The corrected curled recording paper S is then discharged from the discharge roller Rh, serving as an example of a discharge member, with the image fixing surface of the paper facing upwards (so-called front-facing state), to the discharge tray TH1, serving as an example of the discharge section of the paper processing device U4.

[0098] The recording paper S, which is conveyed from the first gate GT1 to the paper reversal path SH4 side of the image recording device U3, is pushed open and then conveyed to the paper reversal path SH4 of the image recording device U3 after passing through the conveying direction restriction member (so-called polyester film gate GT2) made of an elastic film-like component.

[0099] The downstream end of the paper reversal path SH4 of the image recording device U3 is connected to the paper circulation path SH6 and the paper reversal path SH7, and a polyester film gate GT3 is also provided at the connection point. Paper conveyed to the paper reversal path SH4 via the first gate GT1 is conveyed to the paper reversal path SH7 side of the paper handling device U4 via the polyester film gate GT3. In the case of duplex printing, if the recording paper S conveyed via the paper reversal path SH4 is conveyed to the paper reversal path SH7 via the polyester film gate GT3 and then conveyed in the opposite direction (so-called folding), the conveying direction will be restricted by the polyester film gate GT3, and the folded recording paper S will be conveyed to the paper circulation path SH6 side. The recording paper S conveyed to the paper circulation path SH6 will be conveyed again to the secondary transfer area Q4 via the paper feeding path SH1.

[0100] On the other hand, if the recording paper S conveyed on the paper reversal path SH4 is folded back after passing through the polyester film gate GT2 at its rear end and before passing through the polyester film gate GT3, the conveying direction of the recording paper S will be restricted by the polyester film gate GT2, and the recording paper S will be conveyed to the paper conveying path SH5 in a reversed state. After the reversed recording paper S is corrected for curling by the curl correction device U4a, it can be discharged to the paper discharge tray TH1 of the paper processing device U4 with the image fixing surface of the recording paper S facing down (the so-called face-down state).

[0101] The components indicated by symbols SH1 to SH7 constitute the paper transport path SH. Furthermore, the components indicated by symbols SH, Ra, Rr, Rh, SGr, SG1, SG2, BH, and GT1 to GT3 constitute the paper transport device SU.

[0102] (Charger instructions)

[0103] Figure 3 This is a perspective illustration of the charger according to Embodiment 1 of the present invention.

[0104] Figure 4 This is a cross-sectional diagram illustrating the main parts of the charger according to Embodiment 1 of the present invention.

[0105] In addition, Figure 4 To facilitate understanding of the invention, a portion of the shielding electrode has been omitted from the illustration.

[0106] Next, the charger of Example 1 will be described. However, since the chargers CCy to CCk of each color (Y, M, C, K) are constructed in the same way, the charger CCk of color K will be described in detail, and the chargers CCy to CCc of other colors will be omitted in detail.

[0107] exist Figure 2 , Figure 3 , Figure 4 In the embodiment 1, the charger CCk has a charger body 1 extending in the front-to-back direction. The charger body 1 has a shielding electrode 2. The shielding electrode 2 is made of a conductive metal material. The shielding electrode 2 has a plate-shaped upper wall portion 2a extending in the front-to-back direction, and plate-shaped left wall portions 2b and right wall portions 2c extending downward from the left and right sides of the upper wall portion 2a. An opening 2d extending in the front-to-back direction is formed on the left side of the upper wall portion 2a.

[0108] The rear end of the shielding electrode 2 is supported by a rear end block 3, which is an example of one end component, and the front end of the shielding electrode 2 is supported by a front end block 4, which is an example of the other end component. As an example of a support for a cleaning moving component, the upper right part of each of the front and rear blocks 3 and 4 has a cylindrical bearing portion 3a and 4a extending in the front-rear direction.

[0109] As an example of a rotating component, a shaft 6 extending in the front-rear direction is rotatably supported on the shaft seats 3a and 4a. A thread 6a is formed on the outer circumferential surface of the shaft 6. The rear end of the shaft 6 extends rearward through the rear shaft seat 3a, and a driven coupling 7, as an example of a transmission component, is supported at the rear end. The image recording device U3 is equipped with a drive coupling 8, as an example of a transmission component. When the charger CCk is installed in the image recording device U3, the driven coupling 7 is supported in a state of engagement with the drive coupling 8. The drive coupling 8 is configured to transmit drive from an electrode cleaner motor 9, as an example of a drive source for an electrode cleaning component. The electrode cleaner motor 9 in Embodiment 1 uses a motor capable of rotating in both forward and reverse directions.

[0110] Furthermore, in Embodiment 1, an example is shown where shaft 6 is positioned to the right of the charger CCk, but this is not a limitation. Shaft 6 can also be positioned to the top or left of the charger CCk.

[0111] exist Figures 2-4 In this embodiment, the charger body 1 has a linear electrode 11, which serves as a discharge electrode and is an example of a first electrode, disposed inside the body. The linear electrode 11 in Embodiment 1 is composed of a wire extending in the front-back direction. The front and rear ends of the linear electrode 11 are supported by blocks 3 and 4. A grid electrode 12, which serves as a control electrode and is an example of a second electrode, is supported between the linear electrode 11 at the opening position below the shielding electrode 2 and the photosensitive drum Pk (i.e., on the charging area side, the charging area is the area opposite to the photosensitive drum Pk, which serves as an example of a charged component).

[0112] With the linear electrode 11 powered, a voltage is applied to the grid electrode 12 for charge control, thereby causing discharge due to the potential difference between the linear electrode 11 and the grid electrode 12. The discharged charge charges charge the surface of the photosensitive drum Pk.

[0113] (Explanation of the grid electrode)

[0114] Figure 5 This is an explanatory diagram of the grid electrode in Example 1.

[0115] exist Figure 5 In this embodiment, as an example of a mesh portion, the grid electrode 12 has a mesh portion 13 extending along the long side direction (photosensitive drum axis). The mesh portion 13 is formed as a mesh with a plurality of first openings 13a. Edge portions 13b, as an example of beam portions, are formed at both ends of the mesh portion 13 in the width direction (photosensitive drum rotation direction, short side direction).

[0116] The front end of the mesh portion 13, which is one end in the long side direction, is provided with a hook portion 14, which is an example of a tensioned member. The hook portion 14 in Embodiment 1 has a first hook portion 16, a second hook portion 17, a third hook portion 18, and a fourth hook portion 19. The first hook portion 16 to the fourth hook portion 19 are arranged at intervals from one end of the mesh portion 13 toward the other end in the short side direction.

[0117] The first hook portion 16 to the fourth hook portion 19 are each formed as a strip extending along the long side. Openings 16a to 19a are formed inside the first hook portion 16 to the fourth hook portion 19. Therefore, in Embodiment 1, the first hook portion 16 to the fourth hook portion 19 are formed as a quadrilateral frame extending along the long side.

[0118] In Embodiment 1, the lengths of the first hook portions 16 to the fourth hook portions 19 in the long side direction are such that the first hook portions 16 and the fourth hook portions 19, located at both ends in the short side direction, are longer than the second hook portions 17 and the third hook portions 18, located on the inner side in the short side direction. Furthermore, it is preferable that the first hook portions 16 and the fourth hook portions 19 are longer than the second hook portions 17 and the third hook portions 18, but this is not a limitation. It is also possible that all hook portions 16 to 19 have the same length.

[0119] A rear frame portion 31 is provided at the rear end of the mesh portion 13, which is one of the other ends in the long side direction. The rear frame portion 31 has a positioning opening 32, which is one example of a positioning portion.

[0120] (Explanation of tension imparted to components)

[0121] Figure 6 This is an illustration of the main components of a charger in the state of tensioned grid electrodes.

[0122] Figure 7 This is an explanatory diagram of the abutment member in Embodiment 1.

[0123] Figure 8 This is an explanatory diagram of the tension member in Example 1. Figure 8 (A) is a 3D diagram. Figure 8 (B) is from Figure 8 The diagram is viewed from the direction of arrow VIIIB in (A).

[0124] In addition, Figures 6-8 In order to explain the components of the tension grid electrode, other parts and parts unrelated to tensioning are omitted from the illustration.

[0125] exist Figure 6 In the middle, the front end block 4 has a spring mounting part 40 formed on the upper surface of the front end (i.e., the side away from the photosensitive drum Pk) as an example of the mounting part.

[0126] exist Figure 6 , Figure 7 In this example, the front end block 4, which serves as the frame of the charging device, has a front abutment portion 41, which is an example of an abutment member, formed on the lower surface of the front end (i.e., the side near the photosensitive drum Pk). The front abutment portion 41 is shaped to protrude downwards (towards the photosensitive drum Pk). Figure 7 In the middle, the lower surface 41a of the photosensitive drum Pk side of the front abutment portion 41 is formed by a curved surface that bends downward along the outer side in the width direction (short side direction) toward the charger CCk. The lower surface 41a is set as a curved surface corresponding to the curvature of the surface of the cylindrical photosensitive drum Pk.

[0127] Figure 9 This is an enlarged illustration of the bending member in Example 1.

[0128] The front bearing portion 42 of the photosensitive drum Pk has a second front abutment portion 43, which serves as an example of a bending member and a second abutment member, located further rearward than the front abutment portion 41. The second front abutment portion 43 has a plurality of protrusions 43a, which serve as contact portions. The protrusions 43a protrude upward (away from the side of the photosensitive drum Pk). Therefore, the second front abutment portion 43 is formed in a so-called comb-like shape.

[0129] In Embodiment 1, the protrusion 43a is formed such that its length decreases as it moves outward toward the width direction (short side direction) of the charger CCk, according to the curvature of the surface of the photosensitive drum Pk. Specifically, in Embodiment 1, the central protrusion 43a1 of the grid electrode 12 in the short side direction is formed longer than the end protrusion 43a3 relative to the curvature line 43b corresponding to the surface shape of the photosensitive drum Pk. As an example, the end protrusion 43a3 is positioned corresponding to the curvature line 43b, while the central protrusion 43a1 protrudes further upward (away from the photosensitive drum Pk) than the curvature line 43b. The middle protrusion 43a2 is formed such that its protrusion from the curvature line 43b is less than that of the central protrusion 43a1, and its protrusion from the curvature line 43b is greater than that of the end protrusion 43a3.

[0130] Furthermore, when the charger CCk is installed in the image recording device U3, the front abutment 41 and the second front abutment 43 are configured such that the upper end of the protrusion 43a of the second front abutment 43 is located above the lower surface 41a of the front abutment 41.

[0131] In Example 1, as Figure 5 , Figure 6 As shown, the front abutment portion 41 contacts the hook portion 14 of the grid electrode 12 from above. Furthermore, the second front abutment portion 43 contacts the front frame portion 13c of the mesh portion 13 of the grid electrode 12 from below. Compared to the easily damaged mesh portion 13, the contact between the front abutment portion 41 and the front frame portion 13c is less prone to damage, and force is also more easily transmitted.

[0132] Therefore, the grid electrode 12 of Embodiment 1 is held in a state of bending along the surface shape of the photosensitive drum Pk, and is pressed away from the photosensitive drum Pk at multiple positions along the short side direction of the grid electrode 12. In the multiple positions where the grid electrode 12 is pressed, the central side in the short side direction protrudes further away from the photosensitive drum Pk than the end side.

[0133] Furthermore, in Embodiment 1, the grid electrode 12 is held in a state of bending along the surface shape of the photosensitive drum Pk, and there is at least one part (between the protrusions 43a) along the short side direction of the grid electrode 12 that is not pressed toward the side away from the photosensitive drum Pk. In the multiple locations where the grid electrode 12 is pressed, the central side in the short side direction protrudes further away from the photosensitive drum Pk than the end side.

[0134] Therefore, in Embodiment 1, the grid electrode 12 is held in a state of bending along the surface shape of the photosensitive drum Pk, and is pressed at multiple locations along the short side direction of the grid electrode 12 toward the side away from the photosensitive drum Pk. In the multiple locations where the grid electrode 12 is pressed, the pressing force is stronger at the central side in the short side direction than at the end side.

[0135] exist Figure 6 In this example, tension member 51, which is a tension member, is supported at the front end of front block 4.

[0136] exist Figure 6 , Figure 8 In this embodiment, the stretching member 51 has a main body portion 52 extending in the vertical direction. The main body portion 52 in Embodiment 1 is formed in the shape of a plate. Rotatable support portions 53 extending rearward are formed on the left and right sides of the main body portion 52. The rotateable support portions 53 are rotatably supported on the front end block 4 via through holes 54. Therefore, the stretching member 51 can rotate about the through holes 54.

[0137] The upper end of the main body 52 has a rearwardly extending mounting portion 56. The mounting portion 56 has a spring mounting hole 56a. A spring 57, as an example of a tension generating member, is installed between the mounting portion 56 and the spring mounting portion 40.

[0138] The lower part of the main body 52 has a hook claw 60, which is an example of a stretching part. The hook claw 60 has a first claw portion 61, a second claw portion 62, a third claw portion 63, and a fourth claw portion 64 corresponding to the first hook portion 16 to the fourth hook portion 19. Therefore, the first claw portion 61 to the fourth claw portion 64 can support the first hook portion 16 to the fourth hook portion 19 in a hooked state through the openings 16a to 19a that pass through the first hook portion 16 to the fourth hook portion 19.

[0139] In Embodiment 1, the vertical lengths of the first claw portions 61 to 64 (i.e., the lengths extending toward the photosensitive drum Pk) are such that the lengths of the first claw portions 61 and 64 at both ends in the short side direction are longer than the lengths of the second claw portions 62 and 63 on the inner side in the short side direction. That is, the lengths of the first claw portions 61 to 64 are set such that the lower ends of the first claw portions 61 to 64 correspond to the curvature of the surface of the photosensitive drum Pk. Furthermore, it is preferable that the vertical lengths of the first claw portions 61 and 64 are longer than those of the second claw portions 62 and 63, but this is not a limitation. It is also possible that the vertical lengths of all claw portions 61 to 64 are the same.

[0140] Furthermore, in Embodiment 1, the positions of the first claw portion 61 to the fourth claw portion 64 in the front-rear direction are all set to the same position. That is, the first claw portion 61 to the fourth claw portion 64 are positioned aligned with the long side of the grid electrode 12. While it is preferable that the positions of the first claw portion 61 to the fourth claw portion 64 in the front-rear direction are the same, this is not a limitation. For example, the first claw portion 61 and the fourth claw portion 64 may be positioned further outward in the front-rear direction than the second claw portion 62 and the third claw portion 63.

[0141] exist Figure 6 In the case of the charging device frame, the rear end block 3 has a positioning protrusion 71, which is a positioning part, formed on the lower surface of the rear end. The positioning protrusion 71 is installed with its position opening 32 penetrating through the grid electrode 12.

[0142] The lower surface of the rear block 3 has a rear abutment portion 72, which serves as an example of an abutment member. The rear abutment portion 72 is constructed in the same manner as the front abutment portion 41, so a detailed description is omitted.

[0143] Furthermore, the rear bearing portion 73 of the photosensitive drum Pk is formed with a second rear abutting portion 74, which is an example of a second abutting member. The second rear abutting portion 74 is also constructed in the same way as the second front abutting portion 43, so detailed description is omitted.

[0144] exist Figure 5 , Figure 6 In the middle, the rear abutment portion 72 and the second rear abutment portion 74 contact the mesh portion 13 of the grid electrode 12 from above and below. The rear abutment portion 72 and the second rear abutment portion 74 illustrate the manner in which they contact the mesh portion 13, but are not limited to this. For example, the rear frame portion 31 can also be stretched along the long side direction to contact the rear frame portion 31. In addition, among the rear frame portion 31 and the mesh portion 13, the mesh portion 13 has weaker strength and rigidity. Therefore, even if the rear frame portion 31 is bent, the bending of the mesh portion 13 tends to approach a flat shape, but if the mesh portion 13 directly abuts the rear abutment portion 72 and the second rear abutment portion 74, it is expected that the bending will be closer to the target shape.

[0145] Furthermore, the front abutment portion 41 and the second front abutment portion 43 are shown to contact the hook portion 14 and the front frame portion 13c of the grid electrode 12, but are not limited thereto. For example, they may also be configured to contact either the mesh portion 13 or the hook portion 14.

[0146] The tension-applying member 58 of Embodiment 1, consisting of the tensioning member 51, the spring 57, the spring mounting portion 40, etc., applies tension to the grid electrode 12. The tension of the grid electrode 12 can also be adjusted by changing the spring constant of the spring 57. Furthermore, by removing the spring 57 and rotating the tensioning member 51 around the through hole portion 54, the tension of the grid electrode 12 is reduced, thereby allowing the grid electrode 12 to be removed or replaced.

[0147] (The function of Example 1)

[0148] In the charger CCk of Embodiment 1 with the aforementioned structure, the grid electrode 12 is supported by the positioning protrusion 71 at its rear positioning opening 32, and the hook portion 14 at its front end is mounted on the hook claw 60. When the hook portion 14 is mounted on the hook claw 60, it is stretched forward by the elastic force of the spring 57. Therefore, tension acts on the grid electrode 12 in the front-rear direction.

[0149] At the front and rear ends, the front abutment portion 41, the second front abutment portion 43, the rear abutment portion 72, and the second rear abutment portion 74 contact the grid electrode 12 of Embodiment 1. Therefore, the grid electrode 12 is maintained in a state where it is deformed along the surface of the front abutment portion 41, etc., in the short side direction and bent into a shape along the surface of the photosensitive drum Pk.

[0150] By bending the grid electrode 12 of the charger CCk along the photosensitive drum Pk, the distance between the photosensitive drum Pk and the grid electrode 12 becomes uniform from upstream to downstream in the rotational direction of the photosensitive drum Pk. Therefore, charging efficiency can be improved compared to the case where it is not bent. Here, if an abutment portion or the like for bending the grid electrode 12 is provided at the center of the long side direction, the central part of the photosensitive drum Pk will be insufficiently charged in the axial direction. Therefore, it is necessary to apply a bending force to both ends of the grid electrode 12 in the long side direction. However, if the grid electrode 12 is bent at both ends, the central part in the long side direction easily returns to a flat state and cannot maintain a bent state in the entire long side direction. Therefore, the charging capacity will deviate in the long side direction of the charger CCk, and the charging state of the photosensitive drum Pk may deviate. In particular, if the grid electrode 12 is bent, the posture of the grid electrode 12 tends to remain straight in the long side direction under tension. However, if the grid electrode 12 is in a flat state, it is easily suspended due to gravity. Therefore, the two ends of the grid electrode 12 are spaced apart from the photosensitive drum Pk, but in the central part, the grid electrode 12 sometimes sags, causing the gap between it and the photosensitive drum Pk to narrow.

[0151] In the technology described in Patent Document 1, two contact members 53 and 54 are positioned offset along the long side. In Patent Document 1, the electrode member 40 is deformed into a target curved shape by means of the two contact members 53 and 54. Therefore, in Patent Document 1, the distribution of tension along the short side is not considered, and insufficient tension may cause the central portion along the long side to sag.

[0152] In Patent Document 2, only two straight grid electrodes 53 are arranged at an angle. Therefore, in the rotation direction of the photosensitive drum 213, the distance from the photosensitive drum 213 is not constant from upstream to downstream in either the first grid electrode 53 or the second grid electrode 53. As a result, the charging capability deviates.

[0153] In this embodiment 1, the second front abutment portion 43 and the second rear abutment portion 74 are formed such that the front end of the protrusion 43a protrudes at a greater height relative to the curved line 43b in the short-side direction at the center side than at the end side. Therefore, regarding the tension acting on the grid electrode 12, the central side is stronger than the two sides in the short-side direction. That is, the tension on the inner side of the grid electrode 12 in the circumferential direction in the curved state is stronger than the tension on the two sides.

[0154] (Experimental Example)

[0155] An experiment was conducted to investigate how bending the grid electrode 12 caused axial deviation based on the distribution of tension applied to the grid electrode 12 in the short side direction.

[0156] The experiment was conducted using computer simulations to simulate tension distributions along the short side, where the tension is the same in the center and at both ends (flat), stronger in the center than at both ends (central convexity), and weaker in the center than at both ends (central depression). Furthermore, the simulations were performed with both small and large diameter photosensitive drums.

[0157] The degree of deviation of the bending at both ends of the grid electrode 12 relative to the bending (ideal line) of the photosensitive drum Pk and the bending at the center relative to the ideal line was determined when the displacement corresponding to the contact portions 41 and 72 was forcibly applied to both ends of the grid electrode 12 and tension was applied to both ends that were flat, convex in the center, and concave in the center.

[0158] The results are shown in Figure 10 , Figure 11 .

[0159] Figure 10 This is an illustrative diagram of an experimental example with a small photosensitive drum diameter.

[0160] Figure 11 This is an illustrative diagram of an experimental example when the diameter of the photosensitive drum is relatively large.

[0161] exist Figure 10 , Figure 11In the process, it was confirmed that compared to the "flat" or "centrally recessed" cases, the "centrally convex" case exhibits smaller axial deviation, and the stronger the tension, the smaller the deviation. The fact that the two ends in the long side direction are forced to bend along the ideal line (bending line 43b) by the abutment portions 41 and 72, resulting in a small deviation, means that the central portion in the long side direction is also in a bending state close to the ideal line. Furthermore, the small deviation of the "centrally convex" case means that the entire region in the long side direction of the grid electrode 12 is in a bending state closer to the bending of the photosensitive drum Pk. This trend remains consistent even when the diameter of the photosensitive drum changes.

[0162] In the charger CCk of Embodiment 1, the grid electrode 12 is subjected to tension in a "centrally protruding" state. Therefore, compared to the case where the end of the grid electrode 12 in the long side direction abuts against the second abutment portion 43, 74, which has a shape corresponding to the curvature of the photosensitive drum Pk, causing the grid electrode 12 to bend according to the curvature of the photosensitive drum Pk, the bending deviation in the long side direction of the grid electrode 12 can be suppressed.

[0163] In particular, in Embodiment 1, the second abutment portions 43 and 74 are formed in a comb-like shape. Therefore, the second abutment portions 43 and 74 contact the grid electrode 12 intermittently along the short side direction, rather than contacting the entire surface. In the prior art using full-surface contact, it is necessary to ensure the dimensional accuracy of the entire contact area, and the required processing precision and cost are often high. In contrast, in Embodiment 1 with intermittent contact, there are fewer contact points, making it easier to ensure dimensional accuracy and to achieve the desired tension distribution.

[0164] [Example 2]

[0165] Figure 12 This is an explanatory diagram of the abutment member in Embodiment 2, which is the same as that in Embodiment 1. Figure 9 The corresponding diagram.

[0166] In addition, in the description of this embodiment 2, the constituent elements corresponding to the constituent elements of the embodiment 1 are marked with the same symbols, and their detailed descriptions are omitted.

[0167] This embodiment 2 differs from embodiment 1 in the following aspects, but is otherwise identical to embodiment 1.

[0168] exist Figure 12 In Embodiment 2, the second abutment portions 43' and 74' have multiple protrusions 43a' with curvature along the short side direction of the grid electrode 12 instead of the comb-like shape of Embodiment 1. In Embodiment 2, regarding the curvature of each protrusion 43a1' to 43a3', the protrusion on the central side in the short side direction is larger than the protrusion on the end side.

[0169] Furthermore, the central protrusion 43a1' in the short side direction protrudes more than the curved line 43b than the end protrusion 43a3'. Also, there are portions between the curved protrusions 43a1' to 43a3' that do not protrude more than the curved line 43b.

[0170] Therefore, in the charger CCk of Embodiment 2, the grid electrode 12 is also subjected to tension in a "centrally convex" state. Thus, compared to the case where the force stretching the grid electrode 12 is uniform (flat) in the short side direction of the grid electrode 12 or "centrally concave", the deviation of the bending of the grid electrode 12 in the long side direction can be suppressed.

[0171] (Example of Change)

[0172] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments, and various modifications can be made within the scope of the spirit of the present invention as described in the technical solutions. Examples of modifications of the present invention (H01) to (H06) are shown below.

[0173] (H01) In the embodiments described, the invention is not limited to a copier as an example of an image forming apparatus, but can also be applied to image forming apparatuses such as printers and fax machines. Furthermore, it is not limited to color image forming apparatuses, but can also be applied to monochrome image forming apparatuses. Moreover, it is not limited to tandem type image forming apparatuses, but can also be applied to rotary type image forming apparatuses.

[0174] (H02) In the embodiment described, the linear electrode 11 illustrates the case of a single wire, but it is not limited to this and may also be configured to have a structure with two or more wires.

[0175] (H03) In the above embodiment, the structure may also be configured without the shielding electrode 2.

[0176] (H04) In the embodiment described above, a grid corona tube type charger is illustrated, but it is not limited to this. For example, as other discharge type chargers, it can also be used as an electrostatic eliminator or auxiliary charger for photosensitive drums Py to Pk or recording paper S, transfer units T1y to T1k, T2, etc.

[0177] (H05) In the embodiment described above, a mesh-like grid electrode 12 is shown as an example of a control electrode, but it is not limited to this. For example, a control electrode with multiple lines extending along the long side (vertical stripe pattern) can also be applied.

[0178] (H06) In the embodiment described above, the second abutment portions 43, 43', 74, 74' are arranged on the photosensitive drum Pk side, but this is not a limitation. For example, it may also be arranged to be supported by the front end block 4 or the rear end block 3 of the charger Cck via a bracket or arm.

[0179] (Postscript) (1)

[0181] A charging device comprising:

[0182] Discharge electrodes; and

[0183] A control electrode is disposed between the discharge electrode and the charged component.

[0184] The control electrode is held in a curved state along the surface shape of the charged member, and is pressed away from the charged member at multiple locations along the short side direction of the control electrode, and at the multiple locations where the control electrode is pressed, the central side in the short side direction protrudes further away from the charged member than the end side. (2)

[0186] A charging device comprising:

[0187] Discharge electrodes; and

[0188] A control electrode is disposed between the discharge electrode and the charged component.

[0189] The control electrode is held in a curved state along the surface shape of the charged member, and there is at least one part along the short side direction of the control electrode that is not pressed away from the side of the charged member, and in the multiple locations where the control electrode is pressed, the central side in the short side direction protrudes further away from the charged member than the end side. (3)

[0191] A charging device comprising:

[0192] Discharge electrodes; and

[0193] A control electrode is disposed between the discharge electrode and the charged component, and charges are drawn from the discharge electrode toward the charged component.

[0194] The control electrode is held in a bent state along the surface shape of the charged member, and is pressed at multiple locations away from the charged member along the short side direction of the control electrode, and at the multiple locations where the control electrode is pressed, the pressing force is stronger at the center side in the short side direction than at the end side. (4)

[0196] The charging device according to any one of (1) to (3) includes a bending member.

[0197] The bending member is supported by the frame of the charging device and bends by pressing the control electrode away from the member being charged.

[0198] The curved member has a plurality of contact portions extending away from the charged member along the short side direction of the control electrode. Regarding the length of each contact portion, the contact portion on the central side in the short side direction is longer than the contact portion on the end side relative to the surface shape of the charged member. (5)

[0200] The charging device according to any one of (1) to (3) includes a bending member.

[0201] The bending member is supported by the frame of the charging device and bends by pressing the control electrode away from the member being charged.

[0202] The bending member has multiple contact portions with curvature along the short side direction of the control electrode, and the curvature of each contact portion is larger on the central side than on the end side in the short side direction. (6)

[0204] The charging device according to (4) or (5) comprises:

[0205] The control electrode has a frame portion disposed along the outer periphery of the control electrode and a mesh portion disposed inside the frame portion; and

[0206] The curved member contacts the frame portion. (7)

[0208] An image forming apparatus comprising:

[0209] The charged component is composed of an image holding component;

[0210] The charging device according to any one of (1) to (6) energizes the image holding member;

[0211] A latent image forming member forms a latent image on the image holding member;

[0212] The developing member develops the latent image of the image holding member;

[0213] A transfer component that transfers the image developed by the developing component onto a media; and

[0214] A fixing component fixes the image of the medium. (8)

[0216] The image forming apparatus according to (7) includes a bending member.

[0217] The bending member is disposed on the charged member and presses the control electrode away from the charged member to bend it.

[0218] The curved member has a plurality of contact portions extending away from the charged member along the short side direction of the control electrode. Regarding the length of each contact portion, the contact portion on the central side in the short side direction is longer than the contact portion on the end side relative to the surface shape of the charged member. (9)

[0220] The image forming apparatus according to (7) includes a bending member.

[0221] The bending member is disposed on the charged member and presses the control electrode away from the charged member to bend it.

[0222] The bending member has multiple contact portions with curvature along the short side direction of the control electrode, and the curvature of each contact portion is larger on the central side than on the end side in the short side direction. (10)

[0224] The image forming apparatus according to (8) or (9) comprises:

[0225] The control electrode has a frame portion disposed along the outer periphery of the control electrode and a mesh portion disposed inside the frame portion; and

[0226] The curved member contacts the frame portion.

[0227] According to the charging device involved in (1), compared to the case where the end of the control electrode in the long side direction abuts against the abutting part with a shape corresponding to the curvature of the charged member, causing the control electrode to bend according to the curvature of the charged member, the bending deviation of the control electrode in the long side direction can be suppressed.

[0228] According to the charging device involved in (2), compared to the case where the end of the control electrode in the long side direction abuts against the abutting part with a shape corresponding to the curvature of the charged member, causing the control electrode to bend according to the curvature of the charged member, the bending deviation of the control electrode in the long side direction can be suppressed.

[0229] According to the charging device involved in (3), compared to the case where the end of the control electrode in the long side direction abuts against the abutting part with a shape corresponding to the curvature of the charged member, causing the control electrode to bend according to the curvature of the charged member, the bending deviation of the control electrode in the long side direction can be suppressed.

[0230] According to the charging device involved in (4), the tension of the control electrode can be made stronger in the central part than at the end by changing the length of the contact part.

[0231] According to the charging device involved in (5), the tension of the control electrode can be made stronger in the central part than at the end by pressing the control electrode with multiple contact parts with different curvatures.

[0232] According to the charging device involved in (6), compared with the case of contact with the mesh, the control electrode is less likely to be damaged and the force is easier to transmit.

[0233] According to the image forming apparatus of (7), compared to the case where the end of the control electrode in the long side direction abuts against a contact portion of a shape corresponding to the curvature of the charged member, causing the control electrode to bend according to the curvature of the charged member, the bending deviation of the control electrode in the long side direction can be suppressed.

[0234] According to the image forming apparatus involved in (8), the tension of the control electrode can be made stronger in the central part than at the end by changing the length of the contact portion.

[0235] According to the image forming apparatus involved in (9), the tension of the control electrode can be made stronger in the central part than at the end by pressing the control electrode with multiple contact parts of different curvatures.

[0236] According to the image forming apparatus involved in (10), compared with the case of contact with the mesh, the control electrode is less likely to be damaged and the force is easier to transmit.

[0237] The embodiments of the present invention described above are provided for illustrative purposes. Furthermore, these embodiments do not encompass the entirety of the invention, nor do they limit the invention to the disclosed methods. It will be apparent to those skilled in the art that various modifications and variations will be readily understood. These embodiments were chosen and described to most readily explain the principles and applications of the invention. Thus, those skilled in the art can understand the invention through various modifications that are assumed to be optimized for specific uses of various embodiments. The scope of the invention is defined by the foregoing claims and their equivalents.

Claims

1. A charging device comprising: Discharge electrodes; and A control electrode is disposed between the discharge electrode and the charged component. The control electrode is held in a curved state along the surface shape of the charged member, and is pressed away from the charged member at multiple locations along the short side direction of the control electrode, and at the multiple locations where the control electrode is pressed, the central side in the short side direction protrudes further away from the charged member than the end side.

2. A charging device comprising: Discharge electrodes; and A control electrode is disposed between the discharge electrode and the charged component. The control electrode is held in a curved state along the surface shape of the charged member, and there is at least one part along the short side direction of the control electrode that is not pressed away from the side of the charged member, and in the multiple locations where the control electrode is pressed, the central side in the short side direction protrudes further away from the charged member than the end side.

3. A charging device comprising: Discharge electrodes; and A control electrode is disposed between the discharge electrode and the charged component, and charges are drawn from the discharge electrode toward the charged component. The control electrode is held in a bent state along the surface shape of the charged member, and is pressed at multiple locations away from the charged member along the short side direction of the control electrode, and at the multiple locations where the control electrode is pressed, the pressing force is stronger at the center side in the short side direction than at the end side.

4. The charging device according to any one of claims 1 to 3, comprising a bending member, The bending member is supported by the frame of the charging device and bends by pressing the control electrode away from the member being charged. The curved member has a plurality of contact portions extending away from the charged member along the short side direction of the control electrode. Regarding the length of each contact portion, the contact portion on the central side in the short side direction is longer than the contact portion on the end side relative to the surface shape of the charged member.

5. The charging device according to any one of claims 1 to 3, comprising a bending member, The bending member is supported by the frame of the charging device and bends by pressing the control electrode away from the member being charged. The bending member has multiple contact portions with curvature along the short side direction of the control electrode, and the curvature of each contact portion is larger on the central side than on the end side in the short side direction.

6. The charging device according to claim 4 or 5, comprising: The control electrode has a frame portion disposed along the outer periphery of the control electrode and a mesh portion disposed inside the frame portion; and The curved member contacts the frame portion.

7. An image forming apparatus comprising: The charged component is composed of an image holding component; The charging device according to any one of claims 1 to 6 energizes the image holding member; A latent image forming member forms a latent image on the image holding member; The developing member develops the latent image of the image holding member; The transfer component transfers the image developed by the developing component onto a medium; and A fixing component fixes the image of the medium.

8. The image forming apparatus according to claim 7, further comprising a bending member, The bending member is disposed on the charged member and presses the control electrode away from the charged member to bend it. The curved member has a plurality of contact portions extending away from the charged member along the short side direction of the control electrode. Regarding the length of each contact portion, the contact portion on the central side in the short side direction is longer than the contact portion on the end side relative to the surface shape of the charged member.

9. The image forming apparatus according to claim 7, further comprising a bending member, The bending member is disposed on the charged member and presses the control electrode away from the charged member to bend it. The bending member has multiple contact portions with curvature along the short side direction of the control electrode, and the curvature of each contact portion is larger on the central side than on the end side in the short side direction.

10. The image forming apparatus according to claim 8 or 9, comprising: The control electrode has a frame portion disposed along the outer periphery of the control electrode and a mesh portion disposed inside the frame portion; and The curved member contacts the frame portion.

Images