JP2014006429A - Charger, image holder device, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a charger, image holder device, and image forming apparatus that are capable of suppressing nonuniform cleaning which occurs along the direction of the rotation axis of a charging member.SOLUTION: A cleaning body 52B is attached at an angle with respect to a second rotation axis 52A such that the center line of the cleaning body 52B and the axis line of the second rotation axis 52A intersect. Thereby, the cleaning body 52B of a rotating cleaning member 52 swings around the top part F of a charging layer 14B, and alternately comes into contact with an inclined face of the charging layer 14B on one side of the axis and an inclined face of the charging layer 14B on another side of the axis. Accordingly, non-uniform cleaning, which occurs along the rotation axis of a charging roll 14, is suppressed.

Description

  The present invention relates to a charging device, an image carrier device, and an image forming apparatus.

  Patent Document 1 describes a configuration in which a bearing portion is provided that rotatably supports a charging roll that is pressed against a photosensitive drum and driven to rotate and charged, and a sponge member that is pressed against the charging roll and driven to rotate and clean. Has been. The bearing portion includes a bearing hole having a diameter larger than the shaft diameter of the shaft of the sponge member, and supports the sponge member so as to be movable in the press-contact direction to the charging roll (charging member).

JP 2007-127806 A

  The subject of this invention is suppressing the cleaning nonuniformity which arises along the rotating shaft direction of a charging member.

  According to a first aspect of the present invention, there is provided a charging device including a charging body having a larger diameter on the axial center side than both ends in the axial direction. The charging device contacts and rotates with the rotating image holding member. A charging member for charging the image holding member, a rotating shaft extending along a rotating shaft direction of the charging member, and a rotating shaft supported by the rotating shaft and at least partially in contact with the charging member. And a cleaning body extending obliquely with respect to the axis of the rotary shaft, and the driven body is in contact with the rotating charging body and the cleaning body while changing the contact position in the rotational axis direction with the charging body. And a cleaning member that rotates and cleans the charged body.

  The charging device according to a second aspect of the present invention is the charging device according to the first aspect, wherein the cleaning body is formed in a columnar shape, and a center line of the cleaning body and an axis of the rotary shaft are in the rotation axis direction. The charged bodies intersect each other at a position where the diameter is maximized.

  According to a third aspect of the present invention, there is provided an image holding member that is rotatable, and a charging member that charges the surface of the image holding member by being rotated in contact with the rotating image holding member. And a charging device according to claim 1 or 2.

  According to a fourth aspect of the present invention, there is provided an image forming apparatus according to the third aspect, and an electrostatic latent image obtained by exposing the surface of the image holding member according to the third aspect and an image holding member charged on the surface of the image holding apparatus. And a developing device that develops the electrostatic latent image formed on the surface of the image holding member by the exposure device as a toner image.

  According to the charging device of the first aspect of the present invention, as compared with the case where the axis of the rotating shaft and the center line of the cleaning body overlap, the cleaning unevenness generated along the rotating shaft direction of the charging member is suppressed. Can do.

  According to the charging device of the second aspect of the present invention, the position where the center line of the cleaning body and the axis of the rotation shaft intersect in the direction of the rotational axis is shifted from the position where the charged body has the largest diameter. As compared with the above, it is possible to suppress uneven cleaning that occurs along the rotation axis direction of the charging member.

  According to the image carrier device of claim 3 of the present invention, the charge generated along the rotation axis direction on the surface of the image carrier as compared with the case where the charging device according to claim 1 or 2 is not provided. Unevenness can be suppressed.

  According to the image forming apparatus of the fourth aspect of the present invention, in the toner image formed on the surface of the image holding member, compared with the case where the image holding body apparatus according to the third aspect is not provided, the rotation axis direction The density unevenness generated along the line can be suppressed.

(A) (B) (C) It is the side view seen from one which showed the charging device etc. which concern on embodiment of this invention, the front view, The side view from the other direction. (A) (B) (C) It is the side view seen from one which showed the charging device etc. which concern on embodiment of this invention, the front view, The side view from the other direction. (A) (B) (C) It is the side view seen from one which showed the charging device etc. which concern on embodiment of this invention, the front view, The side view from the other direction. (A) (B) (C) It is the side view seen from one which showed the charging device etc. which concern on embodiment of this invention, the front view, The side view from the other direction. It is the top view which showed the charging roll and cleaning member with which the charging device which concerns on embodiment of this invention was equipped. It is the perspective view which showed the charging roll and cleaning member with which the charging device which concerns on embodiment of this invention was equipped. It is the perspective view which showed the charging roll with which the charging device which concerns on embodiment of this invention was equipped. It is the conceptual diagram which showed the evaluation method of the charging device which concerns on embodiment of this invention. It is drawing which showed the evaluation result of the charging device which concerns on embodiment of this invention with the graph. It is drawing which showed the evaluation result of the charging device which concerns on a comparison form with the graph with respect to the charging device which concerns on embodiment of this invention. It is the expanded side view which showed the process cartridge which concerns on embodiment of this invention. 1 is a schematic configuration diagram illustrating an image forming apparatus according to an embodiment of the present invention.

  An example of a charging device, an image carrier device, and an image forming apparatus according to an embodiment of the present invention will be described with reference to FIGS.

(overall structure)
As shown in FIG. 12, the image forming apparatus 10 according to the embodiment of the present invention is a tandem full-color image forming apparatus 10. In each figure, the arrow UP indicates the upper side in the vertical direction.

  Inside the image forming apparatus 10, a cylindrical image carrier 12, a charging device 34 that charges the surface of the image carrier 12, and an electrostatic latent image that is formed on the surface of the image carrier 12, are described below. A process cartridge 18Y as an example of an image holding device for each color of yellow (Y), magenta (M), cyan (C), and black (K). 18M, 18C, and 18K are arranged in order from the upper direction to the lower direction. In the following description, when distinguishing between yellow (Y), magenta (M), cyan (C), and black (K), Y, M, C, and K are described after the reference numerals, and are particularly distinguished. If not, Y, M, C and K are omitted.

[Process cartridge and exposure equipment]
Each color process cartridge 18 is configured to be detachable from the image forming apparatus 10. Further, as the image carrier 12, for example, a conductive cylindrical body in which a photosensitive layer made of an organic photosensitive material or the like is coated on the outer peripheral surface (surface) is used, and the image carrier 12 is driven by a motor (not shown). It is designed to rotate.

  As shown in FIG. 11, a charging roll 14 as an example of a charging member provided in the charging device 34 is disposed so as to contact the outer peripheral surface of the image holding body 12, and the charging roll 14 is connected to the image holding body 12. The surface of the image carrier 12 is charged by being driven to rotate with the rotation.

  Further, as shown in FIG. 12, toward the outer peripheral surface of the image carrier 12 positioned on the downstream side in the rotation direction of the image carrier 12 (arrow D in the figure) with respect to the position where the charging roll 14 contacts. An exposure device 16 that is common to each color and emits a laser beam LB to expose the outer peripheral surface is arranged next to the process cartridge 18. The outer peripheral surface of the charged image carrier 12 is exposed by the laser beam LB emitted from the exposure device 16, and an electrostatic latent image is formed on the outer peripheral surface of the image carrier 12.

  Further, as shown in FIG. 11, the image carrier 12 is formed on the outer circumferential surface of the image carrier 12 on the downstream side in the rotation direction of the image carrier 12 with respect to the portion where the laser beam LB hits on the outer circumferential surface of the image carrier 12. A developing device 24 for developing the electrostatic latent image as a toner image of each color is disposed.

  Further, a cleaning blade that contacts the surface of the image carrier 12 and scrapes foreign matter from the surface of the image carrier 12 on the upstream side in the rotation direction (arrow D in the figure) of the image carrier 12 with respect to the charging roll 14. 26 is provided.

  For example, in the case of forming a full-color image, charging, exposure, and development processes are performed corresponding to each color of black (K), cyan (C), magenta (M), and yellow (Y), A toner image corresponding to each color of black (K), cyan (C), magenta (M), and yellow (Y) is formed on the outer peripheral surface of the image carrier 12 of each color. Details of the charging device 34 will be described later.

[Transfer device]
As shown in FIG. 12, the image forming apparatus 10 includes an endless roll wound around a support roll 40 and a support roll 42 so as to be in contact with the outer peripheral surface of each color image holder 12 aligned in the vertical direction. A sheet transport belt 20 is provided. Further, on the opposite side of the image carrier 12 of each color across the paper conveyance belt 20, a sheet member P as a recording medium conveyed by the paper conveyance belt 20 is formed on the outer peripheral surface of the image carrier 12 of each color. Transfer rollers 22 for transferring the toner images of the respective colors are provided. As described above, the transfer device 36 that transports the sheet member P and transfers the toner image to the sheet member P includes the support roll 40, the support roll 42, the paper transport belt 20, and the transfer roll 22.

[Fixing device / discharge roll]
On the downstream side of the transfer direction of the sheet member P with respect to the transfer device 36 (hereinafter referred to as “sheet member transfer direction”), the toner image transferred to the sheet member P is heated / pressurized to heat the sheet member P. A fixing device 48 for fixing to the image is provided.

  Further, on the downstream side in the sheet member conveyance direction with respect to the fixing device 48, a discharge roll 44 that discharges the sheet member P on which the toner image is fixed to the discharge portion 46 formed in the upper part of the image forming apparatus 10 is provided. Yes.

[Paper storage container / conveying roll]
A sheet storage container 28 that stores a plurality of sheet members P is provided upstream of the transfer device 36 in the sheet member conveyance direction. Further, a take-out roll 30 for taking out the uppermost sheet member P from the paper storage container 28 is provided so as to be in contact with the uppermost sheet member P stacked on the paper storage container 28. Further, on the downstream side in the sheet member conveyance direction with respect to the take-out roll 30, conveyance rolls 32 and 34 that deliver the sheet member P taken out by the take-out roll 30 to the paper conveyance belt 20 are provided.

(Main part configuration)
Next, the charging device will be described.

  As shown in FIG. 1B and FIG. 6, the charging device 34 contacts the charging roll 14 and the charging roll 14 described above, and is driven to rotate as the charging roll 14 rotates to clean the charging roll 14. And a cleaning member 52 to be used. Further, the charging device 34 includes a support device 54 that supports one side of the charging roll 14 and the cleaning member 52, and a support device 56 that supports the other side of the charging roll 14 and the cleaning member 52.

[Charging roll]
As shown in FIGS. 6 and 7, the charging roll 14 that rotates following the rotation of the image carrier 12 includes a conductive first rotary shaft 14 </ b> A that extends along the rotation axis direction of the image carrier 12, and And a charging layer 14B as an example of a charged body in which a conductive elastic layer and a surface layer are sequentially formed around the first rotating shaft 14A.

  As an example, the first rotating shaft 14A has a diameter of 5 mm. Since the first rotating shaft 14A is made thinner than the conventional member in this way, the center side of the first rotating shaft 14A is bent in a state where the charging roll 14 is in contact with the surface of the image holding body 12, and the image holding body 12 and It is conceivable that a uniform pressure contact force (nip force) is not ensured between the two.

  However, the charging layer 14B of the charging roll 14 of the present embodiment has a so-called crown shape in which the center side in the direction of the rotation axis is larger than the both end sides. Thereby, a uniform pressure contact force (nip force) is ensured between the charging roll 14 and the image carrier 12. Note that the crown shape of the charging layer 14B shown in each drawing is exaggerated so that the shape can be easily grasped.

  As a material of the first rotating shaft 14A, for example, free-cutting steel, stainless steel, etc. are used, and materials and surface treatment methods are appropriately selected according to applications such as slidability. Is processed by a general process such as a plating process, and a conductive process is performed.

  The conductive elastic layer (not shown) constituting the charging layer 14B of the charging roll 14 is, for example, carbon black that adjusts the resistance of the conductive elastic layer using an elastic material such as rubber as a base material. Conductive materials such as ionic conductive materials, softeners, plasticizers, curing agents, vulcanizing agents, vulcanization accelerators, anti-aging agents, fillers such as silica and calcium carbonate, etc. can be added to rubber as needed. Materials are added as needed.

  The charging layer 14B is formed by coating the peripheral surface of the conductive first rotating shaft 14A with a mixture in which a material usually added to rubber is added. In addition, as a conductive agent for adjusting the resistance value, a material in which a material that conducts electricity using at least one of electrons and ions as a charge carrier, such as carbon black or an ionic conductive agent mixed in a base material, is used. be able to. Further, the elastic material serving as the base material of the charging layer 14B may be a foam.

  As an example, the elastic material serving as the base material of the charging layer 14B is formed by dispersing a conductive agent in a rubber material. Rubber materials include isoprene rubber, chloroprene rubber, epichlorohydrin rubber, butyl rubber, urethane rubber, silicone rubber, fluorine rubber, styrene-butadiene rubber, butadiene rubber, nitrile rubber, ethylene propylene rubber, epichlorohydrin-ethylene oxide copolymer rubber, epichlorohydrin-ethylene oxide. -Allyl glycidyl ether copolymer rubber, ethylene-propylene-diene terpolymer rubber (EPDM), acrylonitrile-butadiene copolymer rubber, natural rubber, and blended rubbers thereof are used.

  Among these, silicone rubber, ethylene propylene rubber, epichlorohydrin-ethylene oxide copolymer rubber, epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer rubber, acrylonitrile-butadiene copolymer rubber, and blended rubbers thereof are preferably used. These rubber materials may be foamed or non-foamed.

  As the conductive agent, an electronic conductive agent or an ionic conductive agent is used. Examples of electronic conductive agents include carbon blacks such as ketjen black and acetylene black; pyrolytic carbon, graphite; various conductive metals or alloys such as aluminum, copper, nickel, stainless steel; tin oxide, indium oxide, titanium oxide Fine powders such as various conductive metal oxides such as tin oxide-antimony oxide solid solution and tin oxide-indium oxide solid solution; Examples of ionic conductive agents include perchlorates and chlorates such as tetraethylammonium and lauryltrimethylammonium; alkali metals such as lithium and magnesium, perchlorates and chlorates of alkaline earth metals, etc. Can be used.

  These conductive agents may be used alone or in combination of two or more. The amount of addition is not particularly limited, but in the case of an electronic conductive agent, it is preferably in the range of 1 to 60 parts by mass with respect to 100 parts by mass of the rubber material, while in the case of an ionic conductive agent, It is preferable that it is the range of 0.1-5.0 mass part with respect to 100 mass parts of rubber materials.

  The surface layer (not shown) constituting the charging layer 14B is formed for the purpose of preventing contamination by foreign matters such as toner and the like. As a material for the surface layer matrix agent, resin, rubber, etc. Any of them may be used and is not particularly limited. Examples include polyester, polyimide, copolymer nylon, silicone resin, acrylic resin, polyvinyl butyral, ethylene tetrafluoroethylene copolymer, melamine resin, fluoro rubber, epoxy resin, polycarbonate, polyvinyl alcohol, cellulose, polyvinylidene chloride, polychlorinated Vinyl, polyethylene, ethylene vinyl acetate copolymer and the like can be used.

  Of these, polyvinylidene fluoride, a tetrafluoroethylene copolymer, polyester, polyimide, and copolymer nylon are preferably used from the viewpoint of contamination due to external additives. The copolymer nylon includes one or more of 610 nylon, 11 nylon, and 12 nylon as polymerized units, and the other polymer units contained in the copolymer include 6 nylon. 66 nylon and the like. Here, the proportion of polymer units composed of 610 nylon, 11 nylon, and 12 nylon contained in the copolymer is preferably 10% or more in total by weight ratio. When the polymerization unit is 10% or more, the liquid preparation and the film formability at the time of applying the surface layer are excellent, and the wear of the resin layer and the adhesion of foreign matters to the resin layer are reduced especially during repeated use, and the durability of the roll is improved. Excellent, less change in properties due to the environment.

  Moreover, a polymeric material may be used independently and may be used in mixture of 2 or more types. The number average molecular weight of the polymer material is preferably in the range of 1,000 to 100,000, and more preferably in the range of 10,000 to 50,000.

  Furthermore, a conductive material is contained in the surface layer, and the resistance value can be adjusted. The conductive material preferably has a particle size of 3 μm or less.

  In addition, as a conductive agent for adjusting the resistance value, it conducts electrons and / or ions as charge carriers, such as carbon black, conductive metal oxide particles, or ionic conductive agent mixed in a matrix agent. What disperse | distributed material can be used.

  Specifically, carbon black as a conductive agent includes “Special Black 350”, “Special Black 100”, “Special Black 250”, “Special Black 5”, “Special Black 4” manufactured by Degussa, "Special Black 4A", "Special Black 550", "Special Black 6", "Color Black FW200", "Color Black FW2", "Color Black FW2V", "MONARCH1000" manufactured by Cabot, Cabot “MONARCH1300” manufactured by Co., Ltd., “MONARCH1400” manufactured by Cabot, “MOGUL-L”, “REGAL400R”, etc. are used.

  Carbon black has a pH of 4.0 or less, and has better dispersibility in the resin composition due to the effect of oxygen-containing functional groups present on the surface than general carbon black. By doing so, the charging uniformity can be improved, and the fluctuation of the resistance value can be further reduced.

  The conductive metal oxide particles that are conductive particles for adjusting the resistance value are particles having conductivity such as tin oxide, tin oxide doped with antimony, zinc oxide, anatase titanium oxide, ITO, etc. Any conductive agent using electrons as charge carriers can be used without any particular limitation. These may be used alone or in combination of two or more. Further, as long as the present embodiment is not hindered, any particle size may be used, but from the viewpoint of resistance value adjustment and strength, preferably tin oxide, antimony-doped tin oxide, anatase-type titanium oxide, Furthermore, tin oxide and tin oxide doped with antimony are preferred.

  By performing resistance control with such a conductive material, the resistance value of the surface layer does not change depending on environmental conditions, and stable characteristics can be obtained.

  Furthermore, a fluorine-based or silicone-based resin is used for the surface layer. In particular, the surface layer is preferably composed of a fluorine-modified acrylate polymer. Further, fine particles may be added to the surface layer. As a result, the surface layer becomes hydrophobic and acts to prevent the adhesion of foreign matter to the charging roll 14. Further, insulating particles such as alumina and silica are added to provide unevenness on the surface of the charging roll 14, thereby reducing the burden at the time of rubbing against the image holding body 12 and charging roll 14 and the image holding body. It is also possible to improve the mutual abrasion resistance with the 12.

[Cleaning member]
As shown in FIGS. 1 and 6, the cleaning member 52 is a second rotating shaft that extends along the rotating shaft direction of the charging roll 14 (hereinafter sometimes simply referred to as “rotating shaft direction”). The rotating shaft 52A and a cylindrical cleaning member 52B attached to (supported by) the outer peripheral surface of the second rotating shaft 52A (member having a circular cross section) are provided.

  Specifically, as shown in FIG. 5, in the direction of the rotation axis, the center line of the cleaning body 52 </ b> B (one-dot chain line J shown in the drawing) and the axis of the second rotation shaft 52 </ b> A (one-dot chain line K shown in the drawing). ), And the cleaning member 52B is attached to the second rotating shaft 52A so as to intersect at the position of the top F where the diameter of the charging layer 14B is the largest. In other words, on the cut surface obtained by cutting the cleaning member 52 in the direction perpendicular to the second rotation shaft 52A at the position of the top F in the rotation shaft direction, the center of the second rotation shaft 52A and the center of the cleaning body 52B are located. overlapping.

  As shown in FIG. 1A, the center of the cleaning body 52B is on the charging roll 14 with respect to the second rotation shaft 52A on one side in the rotation axis direction (hereinafter simply referred to as “one shaft side”). The cleaning body 52B may be eccentric so that At this time, on the other side in the rotation axis direction (hereinafter simply referred to as “the other side of the shaft”), as shown in FIG. 1C, the center of the cleaning body 52B is charged with respect to the second rotation axis 52A. The cleaning body 52B is eccentric in the direction away from the roll 14. In this case, as shown in FIG. 1B, the inclined surface of the charging layer 14B on one side of the shaft and the outer peripheral surface of the cleaning body 52B are in contact with the top F of the charging layer 14B, and The side slope is cleaned.

  On the other hand, as shown in FIG. 3 (A), the cleaning body 52B is eccentric so that the center of the cleaning body 52B is away from the charging roll 14 with respect to the second rotating shaft 52A on one side of the shaft. As shown in (C), on the other side of the shaft, the cleaning body 52B may be eccentric with respect to the second rotating shaft 52A so that the center of the cleaning body 52B approaches the charging roll. In this case, as shown in FIG. 3B, the inclined surface of the charging layer 14B on the other side of the shaft and the outer peripheral surface of the cleaning body 52B are in contact with the top F of the charging layer 14B. The side slope is cleaned.

  The second rotating shaft 52A is mainly made of metal such as aluminum, stainless steel, free-cutting steel, and the material and surface treatment method are appropriately selected according to applications such as slidability and rust prevention. A non-conductive material may be processed by a general process such as a plating process and subjected to a conductive process, or may be used without being conductive.

  The material of the cleaning body 52B is selected from foamable resins such as polyurethane, polyethylene, polyamide, or polypropylene, NBR, EPDM, SBR, silicon rubber, or the like. The cleaning body 52B efficiently cleans foreign substances such as external additives by driven sliding friction with the charging roll 14, and at the same time does not scratch the surface of the charging roll 14 due to rubbing of the cleaning body 52B. In order to prevent tearing and breakage, polyurethane that is strong against tearing and pulling is particularly preferably used.

  The polyurethane is not particularly limited, and polyols such as polyester polyol, polyether polyester and acrylic polyol, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4-diphenylmethane diisocyanate, tolidine diisocyanate, It only needs to be accompanied by a reaction of an isocyanate such as 1,6-hexamethylene diisocyanate, and a chain extender such as 1,4-butanediol or trimethylolpropane is preferably mixed.

  In general, foaming is performed using a foaming agent such as water, azodicarbonamide, azo compounds such as azobisisobutyronitrile. Further, auxiliary agents such as foaming aids, foam stabilizers, catalysts, etc. may be added as necessary.

[Supporting device]
As shown in FIGS. 1A and 1B, the support device 54 that supports one side of the shaft of the cleaning member 52 includes a support member 66 that has a rectangular parallelepiped shape that supports one end of the second rotary shaft 52A. ing.

  A through hole 66B that rotatably supports one end portion of the second rotation shaft 52A is formed on the center side in the vertical direction of the support member 66 in the drawing, and an upper end portion (upper end portion in the drawing) of the support member 66 is A U groove 66A that supports one end of the first rotary shaft 14A is formed.

  Further, an end portion of a spring 64 that urges the charging roll 14 toward the image carrier 12 is fixed to a lower end portion (lower end portion in the drawing) of the support member 66.

  On the other hand, as shown in FIGS. 1B and 1C, the support device 56 that supports the other shaft side of the cleaning member 52 is configured in the same manner as the support device 54, and the other end portion of the second rotation shaft 52 </ b> A is provided. The supporting member 70 made into the rectangular parallelepiped shape to support is provided.

  A through hole 70B that rotatably supports the other end portion of the second rotating shaft 52A is formed on the center side in the vertical direction of the support member 70 in the drawing, and an upper end portion (upper end portion in the drawing) of the support member 70 is formed at the upper end portion. A U groove 70A that supports the other end of the first rotating shaft 14A is formed.

  In addition, an end portion of a spring 72 that urges the charging roll 14 toward the image holding body 12 is fixed to a lower end portion (lower end portion in the drawing) of the support member 70.

  In this configuration, by attaching the cleaning member 52 and the charging roll 14 to the support device 54 and the support device 56, the inter-axis distance between the first rotation shaft 14A and the second rotation shaft 52A is fixed, and the cleaning member 52 rotates. Regardless of the position, the cleaning body 52B comes into contact with the top F of the charging layer 14B and is compressed by a certain amount.

(Effects of main components)
Next, the operation of the main configuration will be described.

  In order to best understand the positional relationship between the charging roll 14 and the cleaning member 52, when viewed from an orthogonal direction orthogonal to the rotational axis direction (hereinafter simply referred to as “axial orthogonal direction”), FIG. As shown in FIGS. 2B, 3B, and 4B, regardless of the rotational position of the cleaning member 52, the cleaning body 52B comes into contact with the top portion F of the charging layer 14B and reaches a certain amount. It is compressed.

  For example, as shown in FIGS. 1A and 1C, on one side of the shaft, the cleaning body 52B is decentered so that the center of the cleaning body 52B approaches the charging roll 14 with respect to the second rotation shaft 52A. On the other side, the cleaning body 52B may be eccentric so that the center of the cleaning body 52B is away from the charging roll 14 with respect to the second rotation shaft 52A. In this case, as shown in FIG. 1B, the inclined surface of the charging layer 14B on one side of the shaft and the outer peripheral surface of the cleaning body 52B are in contact with the top F of the charging layer 14B.

  When the image carrier 12 is rotated in this state, the charging roll 14 is driven to rotate along with the rotation of the image carrier 12. Further, as the charging roll 14 rotates, the cleaning member 52 rotates by 90 [°].

  When the cleaning member 52 rotates 90 [°], as shown in FIGS. 2A and 2C, the center of the cleaning body 52B in FIG. The cleaning body 52B is eccentric so that it is located on the near side, and on the other side of the shaft, the cleaning body 52B is located so that the center of the cleaning body 52B is located on the back side in FIG. Eccentric. In this state, when viewed from the direction orthogonal to the axis, as shown in FIG. 2B, the cleaning body 52B and the first rotating shaft 14A are parallel to each other, and the cleaning body 52 on one side and the other side of the shaft is charged. It leaves | separates from the layer 14B and the top F of the charging layer 14B and the outer peripheral surface of the cleaning body 52B contact.

  Further, when the cleaning member 52 rotates 90 [°], as shown in FIGS. 3A and 3C, the center of the cleaning body 52 </ b> B is separated from the charging roll 14 with respect to the second rotation shaft 52 </ b> A on one side of the shaft. The cleaning body 52B is decentered so as to be separated, and on the other side of the shaft, the cleaning body 52B is decentered so that the center of the cleaning body 52B approaches the charging roll 14 with respect to the second rotating shaft 52A. In this state, as shown in FIG. 3B, the inclined surface of the charging layer 14B on the other side of the shaft and the outer peripheral surface of the cleaning body 52B are in contact with the top F of the charging layer 14B.

  Further, when the cleaning member 52 rotates 90 [°], as shown in FIGS. 4A and 4C, the center of the cleaning body 52B is located on the one side of the shaft with respect to the second rotation shaft 52A as shown in FIG. The cleaning body 52B is eccentric so as to be located on the back side in FIG. 2B, and the cleaning body 52B is located on the front side in FIG. 2B with respect to the second rotating shaft 52A on the other shaft side. 52B is eccentric. In this state, when viewed from the direction perpendicular to the axis, as shown in FIG. 4B, the cleaning body 52B and the first rotating shaft 14A are parallel, and the top F of the charging layer 14B and the outer peripheral surface of the cleaning body 52B. And contact.

  Thus, the operation | movement demonstrated above arises in order by rotating the cleaning member 52. FIG. That is, when viewed from the direction orthogonal to the axis, the cleaning body 52B of the rotating cleaning member 52 swings around the top F of the charging layer 14B having a crown shape, and the inclined surface on the other side of the shaft of the charging layer 14B. The charging layer 14B alternately contacts with the inclined surface on one side of the axis (see FIGS. 1B and 3B).

  As a result, dirt such as toner and external additives attached to the inclined surfaces on both sides of the charging layer 14B is transferred or scraped to the cleaning body 52B side, so that the center line of the cleaning body and the axis of the second rotating shaft As compared with the case where the two overlap each other, cleaning unevenness that occurs along the rotation axis direction of the charging roll 14 is suppressed.

(Evaluation)
Here, the cleaning performance for the charging roll was evaluated using the cleaning member 52 as an example and the cleaning member as a comparative example.

〔Example〕
[Charging roll]
After adding 3 parts by mass of ionic conductive agent PEL-100 (manufactured by Nippon Carlit Co., Ltd.) to 100 parts by mass of epichlorohydrin rubber and sufficiently kneading it, it was extruded and formed into a first rotating shaft 14A of φ5 [mm] ] (L = 245 mm) SUM-Ni shaft (free-cutting steel (Nippon Steel SUM24EZ) plated with Ni).

  In this state, vulcanization was performed with a press molding machine, and then processing was performed by polishing to obtain an end outer diameter φ6.90 [mm] and a central outer diameter φ7.05 [mm] (crown amount 150 μm). . Thereafter, this surface was coated with a fluororesin with a film thickness of 5 μm by a dip coating method to obtain a charged layer 14B.

  The charging roll 14 obtained in such a process was used for evaluation.

[Cleaning member]
Polyether and isocyanate were mixed, and the obtained urethane resin was heated and cured, and a urethane material (SM55 manufactured by INOAC) having a three-dimensional network structure was processed into a square material of □ 12 [mm] × L220 [mm]. A φ4 [mm] free-cutting steel (Nippon Steel SUM24EZ) coated with Ni on the second rotating shaft 52A is coated with a hot-melt adhesive and inserted into the above-mentioned square material. It processed so that the outer diameter of a urethane part (cleaning body 52B) might become a roll shape of (phi) 6 [mm].

  Here, the center line of the cleaning body 52B and the axis line of the second rotating shaft 52A are crossed at the center in the longitudinal direction of the second rotating shaft 52A, and the center line of the cleaning body 52B and the axis line of the second rotating shaft 52A are Intersect at an angle of 0.04 [°]. Thereby, the position shift of the center of the cleaning body 52B and the center of the 2nd rotating shaft 52A became 0.75 [mm] in the both ends of the cleaning body 52B, respectively.

  Further, regardless of the rotational position of the cleaning body 52B, the first rotating shaft 14A and the second rotating shaft 52A are arranged so that the amount of biting of the cleaning body 52B at the top F of the charging layer 14B becomes 0.3 mm. The distance between the axes was decided. In this state, in the rotation axis direction, the center line of the cleaning body 52B and the axis line of the second rotation shaft 52A intersect at the position of the top F where the charging layer 14B has the largest diameter.

[Comparative example (conventional example)]
[Charging roll]
As the charging roll 14, the same one as in the example was used.

[Cleaning member]
The urethane part (cleaning body) was processed into a roll shape so that the center line of the cleaning body and the axis of the second rotating shaft overlap with the cleaning member used in the example.

  Further, the inter-axis distance between the first rotating shaft member 14A and the second rotating shaft member was determined so that the amount of biting of the cleaning body at the top F of the charging layer 14B was 0.3 [mm].

  Other specifications are the same as in the embodiment.

〔Evaluation method〕
The charging roll and the cleaning member according to the example and the comparative example were incorporated in a process cartridge of CELL 1103cn manufactured by DELL. This process cartridge was attached to a CELL C3110Ccn manufactured by DELL, and a continuous printing test was performed.

  Further, both ends of the first rotating shaft member in the charging rolls of the example and the comparative example were pressed against the image holding body with a force of 4.5 [N] using a spring.

  Furthermore, under three environments of room temperature 10 ° C., humidity 15% RH, room temperature 22 ° C., humidity 55% RH, room temperature 28 ° C., humidity 85% RH, YMCK each color 5%, total 20% image density (per image) A total of 8000 sheets of A4 size paper were output on A4 size paper, and the contamination state of the surface of the charging roll after the output of 8000 sheets was evaluated.

  As an evaluation method, visual observation and magnified observation were performed. In order to quantify the contamination state on the surface of the charging roll, evaluation was performed using the apparatus shown in FIG. 8 after observing the contamination state. Specifically, as shown in FIG. 8, under the environment of room temperature of 22 ° C. and humidity of 55% RH, a voltage of 100 [Vdc] is applied to the bearing electrode 90 having a width (length in the depth direction of the paper) of 5 [mm]. The bearing electrode 90 was moved from one end to the other end of the surface of the charging roll at a speed of 10 [mm / s]. The current value flowing during this movement was sampled and converted to a resistance value. The larger the resistance value, the more contaminated the surface of the charging roll.

  Further, regarding the current value, the charging roll was fixed and collected (at 0 degree), and then the charging roll was rotated around the first rotating shaft member by 180 degrees and collected again (at 180 degrees).

〔Evaluation results〕
As a result of visual observation and magnified observation, the surface of the charging roll 14 according to the example was not contaminated than the surface of the charging roll according to the comparative example.

  FIG. 9 is a graph showing the results of evaluating the charging roll 14 according to the example using the apparatus (see FIG. 8), and FIG. 10 is an evaluation of the charging roll according to the comparative example using the apparatus. The results are shown in a graph.

  In each graph, the vertical axis represents the resistance value [Log-Ω], and the horizontal axis represents the measurement position where one end of the charging roll in the axial direction is 0 [mm]. Further, the solid line in the graph indicates the resistance value collected at 0 degrees, and the broken line indicates the resistance value collected at 180 degrees.

  As shown in FIG. 9, in the charging roll 14 of the example, the difference in resistance value between the center side and both ends of the charging roll 14 is smaller than that of the charging roll of the comparative example shown in FIG. It can be seen that cleaning unevenness that occurs along the direction of the rotational axis 14 is suppressed.

  As can be seen from the above evaluation results, in this embodiment, even when the charging layer 14B of the charging roll 14 has a so-called crown shape, uneven cleaning that occurs along the rotation axis direction of the charging roll 14 occurs. It is suppressed.

  In addition, by suppressing the uneven cleaning that occurs along the rotation axis direction of the charging roll 14, the uneven charging that occurs along the rotation axis direction of the surface of the image carrier 12 is suppressed.

  Further, by suppressing the uneven charging that occurs along the rotation axis direction of the surface of the image holding body 12, the charging unevenness that occurs along the rotation axis direction of the toner image formed on the surface of the image holding body 12 is caused. Density unevenness is suppressed.

  Although the present invention has been described in detail with respect to specific embodiments, the present invention is not limited to such embodiments, and various other embodiments are possible within the scope of the present invention. It is clear to the contractor. For example, in the above-described embodiment, the process cartridge 18 includes the image carrier 12, the charging device 34, and the developing device 24. However, the process cartridge 18 only needs to include the image carrier 12 and the charging device 34. The other apparatus may not be included.

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 12 Image holding body (an example of image holding member)
14 Charging roll (an example of a charging member)
14B Charging layer (an example of a charged body)
16 Exposure device 18 Process cartridge (an example of an image carrier device)
24 Developing device 34 Charging device 52 Cleaning member 52A Second rotating shaft (an example of rotating shaft)
52B Cleaning body

Claims (4)

A charging member that has a charged body whose diameter in the center in the axial direction is larger than that at both ends in the axial direction; and a charging member that charges the image holding member by contacting the rotating image holding member with the charging body and rotating in a driven manner ,
A rotating shaft that extends along the rotation axis direction of the charging member and is rotatable, and is at least partially supported by the rotating shaft and in contact with the charging body and inclined with respect to the axis of the rotating shaft A cleaning member that extends, and cleaning the charging member by rotating the charging member in contact with the rotating cleaning member and changing the contact position of the charging member in the rotation axis direction with the cleaning member.
A charging device comprising: The cleaning body is cylindrical,
2. The charging device according to claim 1, wherein in the rotation axis direction, the center line of the cleaning body and the axis line of the rotation shaft intersect at a position where the diameter of the charging body is maximized. An image holding member that is rotatable;
The charging device according to claim 1, further comprising a charging member that charges the surface of the image holding member by being rotated in contact with the rotating image holding member.
An image carrier apparatus comprising: An image carrier device according to claim 3;
An exposure device that exposes the surface of an image holding member charged on the surface of the image carrier device to form an electrostatic latent image; and
A developing device that develops, as a toner image, an electrostatic latent image formed on the surface of the image holding member by the exposure device;
An image forming apparatus comprising:

Images