JP2005309037A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of realizing sure grounding and the reduction of size in the axial direction of an apparatus main body. <P>SOLUTION: The image forming apparatus has a photoreceptor, a driving shaft for driving and rotating the photoreceptor, a driving means for driving the driving shaft and an inertial member for stably driving and rotating the photoreceptor and provided at the end of the driving shaft, and a conduction member positioned and fixed in the apparatus main body is brought into contact with the inertial member from the shaft direction of the driving shaft. The inertial member is a disk-like flywheel. Then, the conduction member is composed of conductive material being a plate whose edge part coming into contact with the inertial member is like a brush or has elasticity, and the edge part and the apparatus main body are conducted. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrophotographic image forming apparatus such as a copying machine, a facsimile machine, and a printer, and more particularly to a grounding configuration of a photoconductor.

  In an image forming apparatus such as a copying machine, generally, an original image read by an exposure unit is exposed on a photosensitive drum as an image carrier to form an electrostatic latent image. Around the photosensitive drum, there is provided a developing device for forming a toner image in which the latent image is visualized with toner as a developer.

  The developing device charges the toner supplied from the toner hopper to a polarity opposite to that of the electrostatic latent image on the photosensitive drum, and attaches the toner to the surface of the photosensitive drum via the developing sleeve to visualize the image. Yes.

  The photosensitive drum includes a drum base tube in which a conductive metal is formed in a cylindrical shape, and a flange member that is press-fitted into both end openings of the drum base tube to form a bearing portion. A support hole is provided in the center of the flange member, and a drum shaft for supporting and driving the drum unit is inserted into the support hole. An earth plate having an outer peripheral contact portion that comes into contact with the inner peripheral surface of the drum base tube and an inner peripheral contact piece that comes into contact with the outer periphery of the drum shaft is attached to the flange member in order to connect the drum base tube to the apparatus main body. It is.

  In order to ensure the conduction between the inner peripheral surface of the drum base tube and the ground plate, a ground plate with an outer peripheral contact portion located outside the inner diameter of the drum base tube is attached to the inner surface of the flange member, There is a configuration in which the outer peripheral contact portion of the ground plate is press-fitted while scratching the inner peripheral surface of the drum base tube when the flange member is attached. At this time, a part of the ground plate is bent to form a cantilever-shaped inner peripheral contact piece that presses against the drum shaft, and the inner peripheral contact piece contacts the outer peripheral surface of the drum shaft, and the ground plate and the drum Some have been proposed that conduct with the shaft (see Patent Document 1).

  In the drum unit configured as described above, the flange member provided with the ground plate is press-fitted into the drum base tube to achieve conduction between the ground plate and the drum base tube, and an inner peripheral contact piece is used as the drum shaft. The ground plate and the drum shaft are connected by pressure contact.

  By connecting the drum shaft and the apparatus main body, the drum tube and the apparatus main body can be connected. It is important from the viewpoint of image formation and noise to have sufficient conductivity. is there.

  A specific conduction configuration between the drum shaft and the apparatus main body is as follows. That is, the drum base tube that is rotatably supported by the apparatus main body by a bearing or the like is connected to the apparatus main body, so that the drum shaft has a ground plate made of a cantilevered leaf spring or a brush-like ground on the outer peripheral surface of the drum shaft. Generally, a brush is in contact with the brush, or a brush is in contact with the end of the shaft (see Patent Document 1).

JP 10-3197883 A JP-A-9-325542

  However, the above conventional example has the following problems.

  That is, when the ground plate on the leaf spring is brought into contact with the outer peripheral surface of the drum shaft, there is a disadvantage that the contact area with the drum shaft is small and the ground becomes unstable.

  Further, when the earth brush is brought into contact with the outer peripheral surface of the drum shaft, it is necessary to ensure a long axial length in order to increase the contact area, and a drive gear train is formed on the drum shaft. Therefore, the configuration avoids those components, which leads to an increase in the size of the apparatus.

  On the other hand, when contacting the drum shaft end, it is also difficult to secure the contact area, and it is often the case that a flywheel is installed for stable rotation of the drum. There was a thing.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus capable of realizing reliable grounding and reducing the axial size of the apparatus main body.

  In order to achieve the above object, an invention according to claim 1 is provided at a photosensitive member, a driving shaft for rotating the photosensitive member, driving means for driving the driving shaft, and a driving shaft end portion. And an inertia member for stably rotating and driving the photosensitive member, and a conducting member positioned and fixed to the apparatus main body is brought into contact with the inertia member from the axial direction of the drive shaft.

  According to a second aspect of the present invention, in the first aspect of the present invention, the inertia member is a disc-shaped flywheel.

  According to a third aspect of the present invention, in the first aspect of the present invention, the conducting member is formed of a conductive material having a brush-like or elastic plate at the tip portion that contacts the inertia member, and the tip portion, the apparatus main body, Is characterized in that it is conductive.

  According to a fourth aspect of the present invention, in the first aspect of the present invention, the conducting member is in contact with the surface of the inertia member being substantially perpendicular to the surface of the inertia member or inclined in the forward direction with respect to the rotation direction of the inertia member. It is characterized by doing.

  According to the present invention, the tip of the static elimination brush positioned and fixed to the apparatus main body is brought into contact with the flat portion of a disk-like flywheel for stably rotating the photosensitive drum provided at the end of the drum shaft. As a result, stable grounding between the photosensitive drum and the apparatus main body is achieved, and the size of the apparatus main body in the drum axis direction can be reduced.

  An image forming apparatus according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 2 is a cross-sectional view of a one-drum intermediate transfer belt type color image forming apparatus. The configuration and operation will be described below.

  A photosensitive drum 1 as an image carrier is rotatably provided, and a charging roller 2 is disposed above the photosensitive drum 1 to uniformly charge the surface of the photosensitive drum. The laser unit 3 as writing means selectively exposes the surface of the photosensitive drum 1 according to the image signal, and an electrostatic latent image is formed.

  The developing device 4 on the left side of the photosensitive drum 1 visualizes the electrostatic latent image with toner. The developing device 4 includes four developing devices 5Y, 5M, 5C, and 5K that include toners of colors of yellow, magenta, cyan, and black. The color developing devices 5Y, 5M, and 5C mounted on the rotary developing device 6 sequentially perform the developing process so as to face the photosensitive drum 1. Thereafter, the black developing device 5K that has always been opposed to the photosensitive drum 1 is operated to perform the developing process.

  Below the photosensitive drum 1 is an intermediate transfer belt 7 which is an intermediate transfer member. By sequentially transferring the toner images visualized by the developing devices of the respective colors at the primary transfer portion T1, a toner image that has been multiplex-transferred on the surface of the intermediate transfer belt 7 is obtained.

  The recording material P is fed from the paper feeding unit to the registration roller 8. The recording material P waiting on the registration roller 8 is sent to the secondary transfer portion T2 in synchronization with the toner image on the intermediate transfer belt 7.

  The secondary transfer roller 9 as a secondary transfer unit is configured to be able to come into contact with and separate from the intermediate transfer belt 7, and is separated when the multiple transfer process is performed on the intermediate transfer belt 7. When performing the process, contact. The toner image is transferred onto the recording material P at the secondary transfer portion T2.

  The toner image carried on the recording material is fixed to the recording material P by the heat and pressure of the fixing roller 10, and the image formation on the recording material is completed.

  On the other hand, the photosensitive drum 1 is provided with a drum cleaner 11, and the intermediate transfer belt 7 is provided with a transfer cleaner 12. Both of these are blade cleaning systems. The drum cleaner 11 cleans untransferred toner remaining on the photoreceptor in the primary transfer process. The transfer cleaner 12 is configured to be able to contact and separate from the intermediate transfer belt 7 and cleans untransferred toner remaining on the intermediate transfer belt 7 in the secondary transfer process.

  FIG. 1 is a diagram showing a positioning configuration of the photosensitive drum unit 1 in the image forming apparatus with respect to the apparatus main body.

  The process kit 51 is equipped with process means such as the photosensitive drum unit 1 and the developing device 5Y, and can be pulled out from the apparatus main body. In the photosensitive drum unit 1, the flanges 102 and 103 are press-fitted into both ends of the photosensitive drum base tube 101, and the outer diameters of the shaft portions of the flanges 102 and 103 and the inner diameters of the bearings 52 and 53 are fitted. It is positioned in the radial direction by being fixed to the frames 54 and 55 of the kit.

  In addition, a conduction spring 104 is fixed to the flange 103 on the back side, and both end portions are cantilevered leaf springs, and one of them applies a certain pressure to the inner peripheral surface of the drum tube 101. The other is in contact with the other, and the other is in contact with the outer peripheral surface of the drum shaft 111 with a certain pressure applied thereto. This ensures the conduction between the drum tube 101 and the drum shaft 111.

  On the other hand, the photosensitive drum unit 1 is fixed to a drum shaft 111 that is a driving means thereof. A convex portion (C ring 111a) is provided on the back side (right side in the figure) of the drum shaft 111, and a fixing member 112 different from the drum shaft is provided on the front side. 1 is fixed and positioned in the axial direction. The fixing member 112 engages with a groove shape provided at the drum flange and the tip of the drum shaft, transmits the drive from the drum shaft 111 to the photosensitive drum unit 1, and positions the both in the circumferential direction.

  Next, a configuration for fixing the drum shaft 111 to the main body frame and a configuration for driving the photosensitive drum unit 1 will be described.

  The drum shaft 111 is fixed and supported rotatably on the main body frame 60 via a bearing 61. The drum shaft 111 has a drive train on the rear side of the main body frame 60. Specifically, a drum gear 115 is fixed to the drum shaft 111, and the drum drive motor 62 is fixed to the main body frame 60 by a support sheet metal (not shown). Further, idler gears 63 and 64 rotatably connected to the main body frame 60 are connected between the drum drive motor 62 and the drum gear 115, and the driving force of the drum drive motor 62 is transmitted to the drum shaft 111.

  A disc-like flywheel 116 is attached to the rear end portion of the drum shaft 111 via a boss 116 fixedly supported by the drum shaft 111, which contributes to stable rotation when the drum is driven.

  On the other hand, a photoconductor layer such as an organic semiconductor (OPC) is provided on the surface of the drum tube 101 and is uniformly charged by the charging roller 2. Coating unevenness occurs, and as a result, charging unevenness occurs in the drum circumferential direction. Therefore, the photo sensor 65 detects the flag portion 116a of the boss 116 in order to detect the reference position in the circumferential direction of the drum.

  The static elimination brush 66 includes a base portion 66a and a brush portion 66b, and is positioned and fixed to the main body frame. The drum base tube 101 and the main body frame are electrically connected to each other through the boss 116, the drum shaft 111, and the conductive spring 104, and the drum base tube 101 is maintained in a state of being grounded. Here, since the tip of the brush portion 66b of the static elimination brush 66 is in uniform contact with the flat portion of the flywheel 117a, there is an effect that the ground is stabilized.

  Furthermore, the contact pressure can be reduced by tilting the static elimination brush 66 in the forward direction with respect to the rotation direction (arrow direction) with respect to the flat surface portion 117a of the flywheel 111, and durability such as brush shaving can be achieved. Is effective. Further, even when there is a position detection sensor or the like in the drum circumferential direction, the depth direction of the main body can be reduced as compared with the configuration in which the drum shaft 111 is directly contacted.

  The present invention is useful for a grounding configuration of a photoreceptor of an electrophotographic image forming apparatus such as a copying machine, a facsimile machine, or a printer.

1 is a main cross-sectional view of an image forming apparatus according to the present invention. 1 is a diagram showing a drum support configuration of an image forming apparatus according to the present invention. FIG. 3 is a diagram illustrating a static elimination brush support configuration of the image forming apparatus according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 62 Drum drive motor 66 Static elimination brush 101 Drum base tube 102,103 Flange 104 Conduction spring 111 Drum shaft 115 Drum gear 116 Boss 117 Flywheel

Claims (4)

  A photoconductor, a drive shaft for rotating the photoconductor, drive means for driving the drive shaft, and an inertia member for stably rotating the photoconductor provided at the end of the drive shaft. An image forming apparatus comprising: a conductive member that is positioned and fixed to the apparatus main body and is brought into contact with an inertia member from an axial direction of a drive shaft.   The image forming apparatus according to claim 1, wherein the inertia member is a disk-shaped flywheel.   2. The conductive member according to claim 1, wherein a tip portion contacting the inertia member is made of a conductive material of a brush shape or a plate having elasticity, and the tip portion and the apparatus main body are electrically connected. Image forming apparatus.   The image forming apparatus according to claim 1, wherein the conductive member is in contact with the surface of the inertia member in a state of being substantially perpendicular to the surface of the inertia member or inclined in a forward direction with respect to a rotation direction of the inertia member.

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