JP2018013565A - Electrification device and image formation apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrification device and image formation apparatus which have the light load in a bearing member even when deflection and inclination occur in a shaft.SOLUTION: An electrification device includes: an electrification member which has a rotational shaft extending along an electrification object body and electrifies the electrification object body while rotating by being in contact with the electrification object body; a cleaning member which has a rotational shaft extending along the electrification member and cleans the electrification member while rotating by being in contact with the electrification member; a plurality of bearing members which rotatably support the respective shafts of the electrification member and the cleaning member individually; a holding member which holds the plurality of bearing members and holds a distance between the rotational shafts of the electrification member and the cleaning member; a protrusion part which annularly protrudes from the outer peripheral surface of the bearing member by surrounding the rotational shaft, and in which the posture of the bearing member changes with a contact spot contacting the inner peripheral surface of the holding member as a fulcrum; and a rotation stop part which protrudes from a spot connected to the protrusion part of the bearing member and stops rotation of the bearing member contacting the holding member with respect to the holding member.SELECTED DRAWING: Figure 3

Description

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

  Conventionally, as an image forming apparatus provided with a charging device, for example, devices described in Patent Documents 1 and 2 are known.

  In Patent Document 1, a charging roll 14 that is pressed against a photosensitive drum 12 and driven to rotate and charged, and a sponge member 100 that is pressed against the charging roll 14 and driven to rotate and cleaned are rotatable by a bearing member 110. The bearing portion of the sponge member 100 formed on the bearing member 110 is supported as a bearing hole 114 having a diameter larger than the shaft diameter of the shaft 100A of the sponge member 100 to the charging roll 14 with respect to the support portion 100a of the shaft 100A. A technique for providing a degree of freedom in the direction of pressure contact is disclosed. Even if the sponge member 100 is bent due to the pressure contact force, the support member 100a can be freely displaced and deformed in the direction of pressure contact with the charging roll 14 while being supported by the bearing hole 114. Increase is suppressed.

  In Patent Document 2, in order to prevent the occurrence of a bias application failure so that the roller-shaped application member such as a charging roller does not bend, a charging roller (roller-shaped application member) 40 has a circumferential surface near both ends. For example, the protrusion 43 is formed by a heat-shrinkable tube, and the charging roller is placed between the two rolling members 44 with the positions of the respective convex portions sandwiched between them, and is held via the rolling members. The member is in the form of a roller and is rotatably supported by the holder 45 with their axes parallel to each other. The urging member 46 is pressed against the holder so that the urging direction of the urging member is directed to the convex portion. Technology for urging the rolling member with the urging force F of the urging member toward the part and pressing the charging roller against the image carrier through the convex portion to form a discharge gap between the charging roller and the image carrier Is disclosed.

JP 2010-49290 A JP-A-2005-010553

  An object of the present invention is to provide a charging device and an image forming apparatus in which a load on a bearing member is light even when the shaft is bent or tilted.

The charger according to claim 1 is:
A charging member having a rotating shaft extending along the member to be charged, and charging the member to be charged while rotating in contact with the member to be charged;
A cleaning member having a rotating shaft extending along the charging member and cleaning the charging member while rotating in contact with the charging member;
A plurality of bearing members that individually and rotatably support the shafts of the charging member and the cleaning member;
A holding member that maintains the distance between the rotation shafts of the charging member and the cleaning member by holding the plurality of bearing members;
An overhanging portion that surrounds the rotating shaft from the outer peripheral surface of the bearing member and protrudes in an annular shape and comes into contact with the inner peripheral surface of the holding member;
A rotation stop portion that protrudes from a portion connected to the overhang portion of the bearing member and contacts the holding member, and prevents the bearing member from rotating with respect to the holding member;
It is provided with.

An image forming apparatus according to claim 2
An image carrier that forms an image on the surface and holds the image;
A charger for charging the surface of the image carrier;
An image forming device that forms an image on the surface of the image carrier charged by the charger;
A transfer device that transfers the image on the image carrier onto a recording material,
The charger is
A charging member having a rotating shaft extending along the image carrier, and charging the image carrier while rotating in contact with the image carrier;
A cleaning member having a rotating shaft extending along the charging member and cleaning the charging member while rotating in contact with the charging member;
A plurality of bearing members that individually and rotatably support the shafts of the charging member and the cleaning member;
A holding member that maintains the distance between the rotation shafts of the charging member and the cleaning member by holding the plurality of bearing members;
An overhanging portion that surrounds the rotating shaft from the outer peripheral surface of the bearing member and protrudes in an annular shape and comes into contact with the inner peripheral surface of the holding member;
A rotation stop portion that protrudes from a portion connected to the overhang portion of the bearing member and contacts the holding member, and prevents the bearing member from rotating with respect to the holding member;
It is provided with.

  According to the charger according to claim 1 and the image forming apparatus according to claim 2, the burden on the bearing member is light even when the shaft is bent or inclined.

1 is a cross-sectional configuration diagram illustrating a main part in an embodiment of an image forming apparatus. It is a figure which shows the external appearance of a charging device. It is a perspective view which shows the internal structure of a bearing mechanism. It is a 1st sectional view showing the internal structure of a bearing mechanism. It is a 21st sectional view showing the internal structure of a bearing mechanism. It is a figure which shows the structural concept of a bearing member in the state in which the rotating shaft is not fluctuating. It is a figure which shows the structural concept of a bearing member in the state from which the rotating shaft fluctuated.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a cross-sectional configuration diagram illustrating a main part in an embodiment of an image forming apparatus.

  The image forming apparatus 20 of the present embodiment is, for example, a monochrome machine adopting an electrophotographic system, and specifically, is an apparatus such as a printer, a facsimile machine, a copier, or a multifunction machine.

  The image forming apparatus 20 includes a process cartridge 21, a transfer device 22, and a fixing device 23.

  The process cartridge 21 forms a black image, for example, and the transfer device 22 transfers the image formed by the process cartridge 21 onto, for example, a sheet as a recording material. The fixing device 23 fixes the image transferred onto the paper by the transfer device 22 on the paper.

  In the image forming apparatus 20, paper is supplied from a supply device (not shown), and the paper is conveyed along a transfer path between the process cartridge 21 and the transfer device 22 and the fixing device 23. The sheet is sent out of the image forming apparatus 20.

  Here, the structure of the process cartridge 21 will be further described.

  The process cartridge 21 in the present embodiment has a structure in which a photosensitive cartridge 30a and a developing device 34 are combined, and is detachably attached to a main body housing (not shown) of the image forming apparatus 20.

  The photosensitive member cartridge 30a includes a photosensitive member 31, a charger 32, and a cleaner 35 that are incorporated in a common housing, and is detachably attached to the process cartridge 21 as a unit. The charger 32 contacts the photoconductor 31 to charge the surface of the photoconductor, and the cleaner 35 cleans the surface of the photoconductor 31. The charger 32 incorporates a charging roll 42 that contacts the surface of the photoreceptor 31 and a cleaning roll 43 for cleaning the charging roll 42.

  The photoconductor 31 corresponds to an example of an image carrier according to the present invention and also corresponds to an example of a charged body according to the present invention. The charger 32 corresponds to an embodiment of the charger of the present invention, the charging roll 42 corresponds to an example of a charging member referred to in the present invention, and the cleaning roll 43 corresponds to an example of a cleaning member referred to in the present invention. . Details of the charger 32 will be described later.

  The developing device 34 accommodates a developer therein and develops the electrostatic latent image on the photoreceptor 31.

  In the part where the process cartridge 21 is mounted in the image forming apparatus 20, the photosensitive member 31 is faced between the charger 32 and the developing unit 34 of the process cartridge 21, and an electrostatic latent image is written on the photosensitive member 31. For example, an LED array 33 is provided as an exposure device.

  The transfer device 22 has a transfer roll 71 facing the photoconductor 31, and a transfer bias is applied to the transfer roll 51 to form a transfer electric field between the photoconductor 31 and the transfer roll 71. The image on the photosensitive member 31 is transferred to a sheet by an electric field.

  The fixing device 23 includes a heating roll 61 having a heater therein, and a pressure roll 62 that contacts and pressurizes the heating roll 61, and a fixing region between the heating roll 61 and the pressure roll 62 is provided. The image on the paper is heated and pressed to be fixed on the paper.

  Hereinafter, the structure of the charger 32 will be further described.

  FIG. 2 is a diagram illustrating an appearance of the charger 32.

  The charger 32 has a structure in which the above-described charging roll 42 and cleaning roll 43 are incorporated in the housing 41.

  The charging roll 42 has a rotating shaft made of, for example, a conductive material such as metal, and a charging layer is formed at a portion excluding both ends of the rotating shaft.

  The cleaning roll 43 also has a rotating shaft formed of a conductive material such as metal. Then, for example, a sponge material is wound around the rotating shaft as a cleaning material in a spiral shape to form a sponge layer. As the material for the sponge layer, a material selected from foamable resins such as polyurethane, polyethylene, polyamide, or polypropylene, or rubber is used.

  The cleaning roll 43 is pressed by the charging roll 42 and is loaded. For this reason, the sponge layer is elastically deformed along the peripheral surface of the charging roll 42 to form a contact area. The charging roll 42 is pressed against the photoconductor 31 and is loaded.

  The photosensitive member 31 that contacts the charging roll 42 is driven to rotate by a motor (not shown). In this embodiment, the charging roll 42 is driven to rotate by receiving the rotational force of the photosensitive member 31. Further, in this embodiment, the cleaning roll 43 is driven to rotate by receiving the rotational force of the charging roll 42. Note that the charging member and the cleaning member referred to in the present invention may rotate by themselves.

  Unnecessary substances such as toner and external additives attached to the surface of the charging roll 42 are removed from the surface of the charging roll 42 by the cleaning roll 43 when the cleaning roll 43 rotates in contact with the charging roll 42. The removed unnecessary material is taken into the foam cell of the cleaning roll 43, and the unnecessary material aggregates in the cell. As a result, when unnecessary aggregates have a certain size, the cleaning roller 43 returns to the photosensitive member 31 via the charging roller 42 and is collected by the cleaner 35 of the photosensitive member 31.

  The housing 41 includes bearing mechanisms 100 and 200 for rotatably holding both ends of the charging roll 42 and the cleaning roll 43. Of the bearing mechanisms 100 and 200 at both ends, one of the bearing mechanisms 100 incorporates a power feeding mechanism that supplies a voltage to the charging roll 42, but the details of the power feeding mechanism will be omitted.

  The internal structure of the bearing mechanisms 100 and 200 will be described below, but only the structure common to the bearing mechanisms 100 and 200 at both ends will be described.

  3-5 is a figure which shows the internal structure of the bearing mechanisms 100 and 200. FIG. 3 is a perspective view, and FIGS. 4 and 5 are cross-sectional views at different cutting positions.

  FIG. 3 shows a state in which the rotating shafts 42 a and 43 a of the charging roll 42 and the cleaning roll 43 are cut leaving the ends held by the bearing mechanisms 100 and 200.

  A positioning holder 110 is incorporated in the bearing mechanisms 100 and 200, and the positioning holder 110 holds two bearing members 120 and 130. The positioning holder 110 corresponds to an example of a holding member according to the present invention, and the bearing member 120 (130) corresponds to each example of a bearing member according to the present invention.

  The positioning holder 110 is made of, for example, a general resin (for example, POM). The positioning holder 110 is formed with recesses 112 and 113 into which the bearing members 120 and 130 are individually fitted.

  The rotating shaft 42 a of the charging roll 42 is rotatably held by the first bearing member 120, and the rotating shaft 43 a of the cleaning roll 43 is rotatably held by the second bearing member 130. Each of the bearing members 120 and 130 is formed of a resin material having high slidability and wear resistance, for example, non-conductive POM, and has a circular cross-sectional concave portion 121 into which each of the rotation shafts 42a and 43a is fitted. 131.

  The positioning holder 110 maintains the distance between the rotation shafts 42 a and 43 a of the charging roll 42 and the cleaning roll 43 by holding the bearing members 120 and 130. The bearing members 120 and 130 are fitted in the recesses 112 and 113 of the positioning holder 110. The portion where the bearing member 120 (130) is in contact with the inner wall of the recess 112 (113) is an annular flange. 124 (134). The flange 124 (134) is formed in an annular shape around the peripheral wall of the bearing member 120 (130), and is an example of an overhanging portion according to the present invention that protrudes outward from a part of the peripheral wall. The cross-sectional shape of the ridge 124 (134) may be a trapezoidal shape or a rectangular shape with a flat ridge, or may be a semicircular shape or a triangular shape with a sharp ridge.

  This ridge 124 (134) is a case where the angle of the rotating shafts 42a and 43a fluctuates because the ridge of the ridge 124 (134) and the inner wall of the recess 112 (113) are in linear contact (or a thin strip shape). However, the bearing member 120 (130) changes its direction following the angle fluctuation of the rotating shafts 42a and 43a with the contact point as a fulcrum. As a result, the bearing member 120 (130) maintains a posture facing the rotating shafts 42a and 43a, so that one-side reduction or the like is suppressed.

  Further, the bearing member 120 (130) is formed with a rotation stop portion 125 (135) as an example of the rotation stop portion referred to in the present invention. The rotation stopper 125 (135) protrudes outward from the peripheral wall of the bearing member 120 (130), and stops the rotation of the bearing member 120 (130) relative to the positioning holder 110 by contacting the positioning holder 110, for example. Yes. In the present embodiment, the rotation stopper 125 (135) is provided at a position adjacent to the collar 124 (134).

  Here, the positional relationship between the rotation stopper 125 (135) and the flange 124 (134) will be considered.

  6 and 7 are views showing the structural concept of the bearing member 120 (130). FIG. 6 shows a state where the rotating shafts 42a and 43a are not changing, and FIG. 7 shows a state where the rotating shafts 42a and 43a are changed. 6A and 7A are side views, and FIG. 6B and FIG. 7B are front views.

  The bearing member 120 (130) is provided with an annular flange 124 (134) around the peripheral wall, and the rotation stopper 125 (135) is provided at a position adjacent to the flange 124 (134). Here, for comparison, a state in which the rotation stopper 125 (135) is provided at a position away from the collar 124 (134) is indicated by a dotted line.

  Here, considering the case where the rotating shafts 42a and 43a fluctuate from the state shown in FIG. 6 to the state shown in FIG. 7, the bearing member 120 (130) changes its direction with the ridge of the flange 124 (134) as a fulcrum. Then, as the direction of the bearing member 120 (130) changes, the position of the rotation stopper 125 (135) moves. When the movement amount of the rotation stopper 125 (135) before and after the fluctuation of the rotation shafts 42a and 43a is viewed, the movement amount d1 when the rotation stoppers 125 (135) are in contact with the collar 124 (134) is larger than that of the collar 124 (134). It can be seen that the amount of movement d2 in the case of being away is larger. Such movement of the rotation stopper 125 (135) restricts the range in which the orientation of the bearing member 120 (130) can change following the fluctuation of the rotation shafts 42a and 43a. That is, when the rotation stopper 125 (135) is in contact with the flange 124 (134), the range of change in the direction of the bearing member 120 (130) is not so limited, but the rotation stopper 125 (135) is not limited to the flange 124. If it is away from (134), the change range of the direction of the bearing member 120 (130) is limited.

  Therefore, when the rotation stopper 125 (135) is provided in contact with the flange 124 (134), the bearing member 120 (130) is lightly loaded even if a large variation occurs in the rotation shafts 42a and 43a, and the rotation is reduced. It can be seen that it is avoided.

  Note that the rotation stopper 125 (135) does not necessarily need to be integrally formed as long as the rotation stopper 125 (135) is provided in contact with the flange 124 (134). (134) may be provided so as to partially bite, or the rotation stopper 125 (135) may be provided so as to protrude from a part of the ring of the flange 124 (134).

  As shown in FIGS. 4 to 6, in the present embodiment, the rotation stopper 125 (135) is provided at a position adjacent to the flange 124 (134) because the outer shape of the flange 124 (134) is simple. This is because higher accuracy can be obtained at the time of molding than in the case of an outer shape having an uneven ring.

  20... Image forming apparatus 21... Process cartridge 31... Photoconductor 32. Charger 33. LED array 34 .Developer 42. Charging roll 43 43 Cleaning roll 42a, 43a ... rotating shaft, 100, 200 ... bearing mechanism, 110 ... positioning holder, 120, 130 ... bearing member, 124, 134 ... 鍔, 125, 135 ... anti-rotation part,

Claims (2)

A charging member having a rotating shaft extending along the member to be charged, and charging the member to be charged while rotating in contact with the member to be charged;
A cleaning member having a rotating shaft extending along the charging member, and cleaning the charging member while rotating in contact with the charging member;
A plurality of bearing members that individually and rotatably support the shafts of the charging member and the cleaning member;
A holding member that maintains the distance between the rotating shafts of the charging member and the cleaning member by holding the plurality of bearing members;
An overhanging portion that changes the posture of the bearing member around the contact point, which is in contact with the inner circumferential surface of the holding member, surrounding the rotating shaft from the outer circumferential surface of the bearing member;
A rotation stop portion that protrudes from a portion connected to the overhang portion of the bearing member and contacts the holding member, and prevents the bearing member from rotating with respect to the holding member;
A charging device comprising: An image carrier that forms an image on the surface and holds the image;
A charger for charging the surface of the image carrier;
An image forming device that forms an image on the surface of the image carrier charged by the charger;
A transfer device for transferring an image on the image carrier onto a recording material,
The charger is
A charging member having a rotating shaft extending along the image carrier, and charging the image carrier while rotating in contact with the image carrier;
A cleaning member having a rotating shaft extending along the charging member, and cleaning the charging member while rotating in contact with the charging member;
A plurality of bearing members that individually and rotatably support the shafts of the charging member and the cleaning member;
A holding member that maintains the distance between the rotating shafts of the charging member and the cleaning member by holding the plurality of bearing members;
An overhanging portion that changes the posture of the bearing member around the contact point, which is in contact with the inner circumferential surface of the holding member, surrounding the rotating shaft from the outer circumferential surface of the bearing member;
A rotation stop portion that protrudes from a portion connected to the overhang portion of the bearing member and contacts the holding member, and prevents the bearing member from rotating with respect to the holding member;
An image forming apparatus comprising:

Images