JP4761185B2 - Developing cartridge and image forming apparatus - Google Patents

Description

  The present invention relates to a developing cartridge and an image forming apparatus in an image forming apparatus such as a printer, a copying machine, or a facsimile.

Up to now, an electrophotographic image forming apparatus has a problem that toner is scattered during development, and the inside of the image forming apparatus main body is soiled.
Therefore, when a developing cartridge equipped with a developing sleeve (developer carrier) and a photosensitive drum (image carrier) has been mounted on an image forming apparatus main body equipped with a transfer device, the developing sleeve becomes a photosensitive drum. A conductive member is provided on the downstream side in the rotation direction of the developing sleeve from the closest position, and a voltage is applied to the conductive member, and scattered toner generated during development is transferred onto the conductive member, the developing sleeve, or the photosensitive drum. It is known to electrically adhere and prevent contamination inside the image forming apparatus main body due to scattered toner (see Patent Document 1).

JP2000-112234A

  However, the above method can prevent contamination in the image forming apparatus main body due to scattered toner, but since a conductive member to which a predetermined voltage is applied is disposed, spark (discharge) is caused in the image forming apparatus main body. ) May occur.

  It is an object of the present invention to electrically attach scattered toner during development to an image carrier or a conductive member to prevent contamination of the image forming apparatus main body due to the scattered toner, and to form an image forming apparatus. The purpose is to prevent sparks in the body.

  In order to solve the above-described problems, the present invention is characterized in that a developing cartridge that can be attached to and detached from an image forming apparatus main body, an image carrier provided to face a transfer device, and the image carrier A conductive member provided on the upstream side of the sheet conveying direction at a position where the body faces the transfer device, and a discharge preventing means for preventing a discharge generated between the conductive member and the transfer device And a developing cartridge. As a result, it is possible to prevent contamination in the image forming apparatus main body due to scattered toner, and it is possible to prevent electric discharge generated between the conductive member and the transfer device.

  Preferably, the discharge preventing means is a developing cartridge composed of an insulating member that covers a front end portion of the conductive member. Thereby, the electric discharge which arises between an electroconductive member and a transfer apparatus can be prevented.

  Preferably, the transfer device is a developing cartridge that includes a transfer roll and a conductive bearing member that supports the transfer roll, and a predetermined voltage is applied to the transfer roll via the bearing member.

  Preferably, the discharge preventing means is a developing cartridge in which a portion of the conductive member facing the bearing member in the longitudinal direction is separated from the transfer device than other portions. Thereby, the electric discharge which arises between an electroconductive member and a transfer apparatus can be prevented.

  Preferably, the discharge preventing means is a developing cartridge in which a portion facing the bearing member in the longitudinal direction of the conductive member has an arc shape. In the present invention, the “arc shape” includes a part of a circle and a part of an ellipse. As a result, it is possible to prevent electric discharge between the conductive member and the transfer device without concentrating the electric charge on one point of the conductive member.

  Preferably, the discharge preventing means is a developing cartridge in which a portion facing the bearing member in the longitudinal direction of the conductive member has an oblique shape. The “oblique shape” means that a portion of the conductive member facing the bearing member in the longitudinal direction is cut off obliquely. Thereby, since the distance between the portion facing the bearing member in the longitudinal direction and the transfer device can be increased, it is possible to prevent electric discharge generated between the conductive member and the transfer device.

  The second feature of the present invention is that an image carrier on which a latent image is formed, a developing device that carries a developer on the image carrier, and the image carrier that faces the image carrier. A transfer device that transfers the developer image of the carrier onto the paper, and the image carrier is provided on the upstream side in the paper conveyance direction at a position facing the transfer device, and is applied with a predetermined voltage. The image forming apparatus includes a member and a discharge preventing means for preventing a discharge generated between the conductive member and the transfer device. As a result, it is possible to prevent contamination in the image forming apparatus main body due to scattered toner, and it is possible to prevent electric discharge generated between the conductive member and the transfer device.

Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an outline of an image forming apparatus 10 according to an embodiment of the present invention. The image forming apparatus 10 includes an image forming apparatus main body 12, an image forming unit 14 is mounted in the image forming apparatus main body 12, and a discharge unit 16 is provided on the upper portion of the image forming apparatus main body 12. For example, two-stage sheet feeding units 18 are disposed below the image forming apparatus main body 12.

  Each paper feed unit 18 has a paper feed cassette 20 in which paper is stored and paper feed rolls 22a and 22b. Sheets stacked on the paper feed cassette 20 are registered by the rotation of the paper feed rolls 22a and 22b. It is conveyed to the roll 24.

  Further, an image carrier 28 and a transfer device 36 of a process cartridge (developing cartridge) 46 described later are provided on the downstream side of the registration roll 24, and a fixing device 40 is further provided on the downstream side thereof.

  Accordingly, the sheet fed from the sheet feeding cassette 20 of the sheet feeding unit 18 by the sheet feeding rolls 22a and 22b is temporarily stopped by the registration roll 24, and the timing between the image carrier 28 and the transfer device 36, which will be described later, is taken. The developer image is transferred through the gap, and the transferred developer image is fixed by the fixing device 40 and discharged to the discharge portion 16 by the discharge roll 26.

The image forming means 14 is of an electrophotographic type, and includes an image carrier 28 made of a photoconductor, a charging device 30 made of, for example, a charging roll for uniformly charging the image carrier 28, and charging by the charging device 30. An optical writing device 32 that writes a latent image on the image carrier 28 by light, a developing device 34 that visualizes the latent image of the image carrier 28 formed by the optical writing device 32 with a developer, A transfer roller 73 and a conductive bearing member 74 that supports the transfer roller. A predetermined voltage is applied to the transfer roller 73 via the bearing member 74, and a developer image by the developing device 34 is applied to a sheet. A transfer device 36 for transferring, a cleaning device 38 for cleaning the developer remaining on the image carrier 28, and a fixing roller for fixing the developer image on the paper transferred by the transfer device 36 to the paper. And a fixing device 40 that consists of Le and the heating roll. The optical writing device 32 is composed of, for example, a scanning type laser exposure device, traverses a process cartridge 46 described later, and forms a latent image on the image carrier 28. The cleaning device 38 includes a cleaning blade 42 that comes into contact with the image carrier 28 and a developer recovery unit 44 that stores the developer scraped off by the cleaning blade 42.
The optical writing device 32 may use an LED or a surface emitting laser as another embodiment.

Next, a process cartridge (developing cartridge) 46 according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 2 shows an outline of the process cartridge 46 according to the first embodiment of the present invention.
The process cartridge 46 according to the first embodiment of the present invention is an integrated image carrier 28, charging device 30, developing device 34 and cleaning device 38, which can be replaced as a unit. . The process cartridge 46 is provided with an opening / closing lid 29 outside the image carrier 28. The opening / closing lid 29 is positioned so as to cover the image carrier 28 when the process cartridge 46 is not attached to the image forming apparatus main body 12, and the image carrier when the process cartridge 46 is attached to the image forming apparatus main body 12. As shown in FIG. 1, the image carrier 28 moves above the holder 28, the image carrier 28 appears on the outer surface of the process cartridge 46, and the process cartridge 46 is attached to the image forming apparatus main body 12. And the transfer device 36 face each other. Further, the process cartridge 46 is provided with a handle portion 39 extending obliquely upward from the cleaning device 38 and having a tip portion curved downward. Accordingly, when the process cartridge 46 is taken out from the image forming apparatus main body 12, the process cartridge 46 can be easily taken out from the image forming apparatus main body 12 by grasping the handle 39 and pulling out the process cartridge 46.

  The developing device 34 is divided into a developer container 50 for storing a developer and a developing unit 52. The developer container 50 includes a container body 53 having an opening 51 formed on the surface opposite to the side on which the image carrier 28 is disposed, and a lid member 55 that closes the opening 51. ing. The developer container 50 has an agitator (developer stirring member) 54 disposed therein. The agitator 54 has a flexible stirring plate 56 such as PET (polyethylene terephthalate). When the amount of toner in the developer container 50 decreases, the leading edge 57 of the stirring plate 56 becomes the container body. The developer container 50 and the developing unit 52 communicate with each other via the developer supply port 60, and the developer container 50 and the developing unit 52 communicate with each other through the developer supply port 60. The agent is conveyed.

  In the developing section 52, a developing roll (developer carrier) 58 having a magnet roll disposed therein is disposed. The developing roll 58 faces the image carrier 28 at, for example, the lower part of the image carrier 28, and the opposed part is a development position. A predetermined voltage is applied to the developing roll 58.

  The blade device 62 includes a developing blade 64 and an attachment portion 66. The developing blade 64 is made of an elastic resin such as polyurethane or silicone rubber and is disposed in the developing unit 52. One end of the developing blade 64 is fixed to the developer container 50 via an attachment portion 66. The attachment portion 66 is made of sheet metal, and one end of the developing blade 64 is fixed to the attachment portion 66 by hot melt or the like. The developing blade 64 is elastically deformed and in contact with the developing roll 58 before the other end, and the developer blade 64 regulates the layer thickness of the developer on the developing roll 58, and the developer whose layer thickness is regulated. The latent image on the image carrier 28 is developed at the development position.

  The process cartridge 46 according to this embodiment includes a conductive member 68 on the upstream side in the sheet conveyance direction at a position where the image carrier 28 faces the transfer device 36 when the process cartridge 46 is mounted on the image forming apparatus main body 12. Yes. The conductive member 68 is formed of a film-like sheet having substantially the same length as the axial direction length in the axial direction of the transfer device 36 and the image carrier 28. Although not shown in the figure, a voltage equal to the voltage applied to the developing roll 58 is applied to the conductive member 68 by a circuit branched from the circuit for applying a voltage to the developing roll 58. The entire length of the conductive member 68 in the axial direction, that is, the entire length in the longitudinal direction, the transfer device 36 side (outside of the conductive member 68) and the tip 69 are substantially J-shaped as shown in the cross-sectional view of FIG. It is covered in a non-contact state by an insulating film 70 formed on the surface. On the other hand, in the transfer device 36, as shown in the side view of FIG. 4, both axial ends of the rotation shaft 72 of the transfer roll 73 are supported by a conductive bearing member 74, and the conductive member 68 is supported by the bearing member 74. A predetermined voltage having a polarity opposite to the voltage applied to is applied. Accordingly, since there is a potential difference between the bearing member 74 and the conductive member 68 of the transfer device 36, there has been a possibility that spark (discharge) may occur between them, but the conductive member 68 as described above. By covering the surface with the insulating film 70, it is possible to prevent a spark that may occur between the conductive member 68 and the transfer device 36.

  Note that the outer side of the conductive member 68 is covered with the insulating film 70 because when the conveyed paper contacts the conductive member 68, there is a risk of leakage between the conductive member 68 and the transfer device 36 via the paper. Because there is. The insulating film 70 may have a shape other than a substantially J shape as long as it can cover the tip portion 69 of the conductive member 68. For example, the insulating film 70 has a substantially L shape as shown in FIG. You may form in a letter shape. In this embodiment, the front end portion 69 of the conductive member 68 is covered with a substantially J-shaped insulating film 70 over the entire length in the longitudinal direction of the conductive member 68. Since it is between the bearing member 74 of the apparatus 36 and the longitudinal direction both ends of the electroconductive member 68, the electroconductive member 68 is the insulating film 70 which processed only the both ends of the longitudinal direction in the substantially J shape or the substantially L shape. May be covered.

Next, a process cartridge 46 according to the second embodiment will be described with reference to the drawings.
Similar to the process cartridge 46 of the first embodiment, the process cartridge 46 of this embodiment is in the sheet transport direction at a position where the image carrier 28 faces the transfer device 36 when mounted on the image forming apparatus main body 12. A conductive member 68 is provided on the upstream side. The conductive member 68 is formed of a film-like sheet having substantially the same length as the axial length of the transfer roll 73 and the image carrier 28 in the axial direction. Although not shown in the figure, a voltage equal to the voltage applied to the developing roll 58 is applied to the conductive member 68 by a circuit branched from the circuit for applying the voltage to the developing roll 58. An insulating film 70 is disposed on the 36 side (outside of the conductive member 68). In this embodiment, the leading end portions 78 on both ends in the longitudinal direction of the conductive member 68 have an R shape as shown in a side view of FIG. In this embodiment, the front end portions 78 on both ends in the longitudinal direction of the conductive member 68 have a circular arc shape that is a part of a circle, but may be a circular arc shape that is a part of an ellipse other than a circle. In this way, contamination in the image forming apparatus main body 12 due to scattered toner can be prevented, and the conductive member 68 and the transfer can be transferred without concentrating the charge at one point 78 at both ends in the longitudinal direction of the conductive member 68. The occurrence of sparks between the devices 36 can be prevented.

  In this embodiment, the bearing members 74 at both ends in the axial direction of the transfer device 36 have a shape in which corners 76 on the side close to the conductive member 68 are obliquely cut off as shown in FIG. Yes. By doing in this way, the distance between the bearing member 74 and the electroconductive member 68 can be earned, and generation | occurrence | production of the spark between the electroconductive member 68 and the bearing member 74 can be prevented more reliably. . Also in this embodiment, the distal end portion 69 of the conductive member 68 may be covered with an insulating film 70 having a substantially J shape or a substantially L shape.

  It should be noted that the front end portions 78 on both ends in the longitudinal direction of the conductive member 68 may have a diagonal shape, that is, a shape in which corner portions are cut off obliquely as shown in the side view of FIG. In this way, contamination in the image forming apparatus main body 12 due to the scattered toner can be prevented, and the distance between the front end portions 78 on both ends in the longitudinal direction of the conductive member 68 and the bearing member 74 can be increased. The occurrence of sparks between the sex member 68 and the bearing member 74 can be prevented.

  As described above, according to the present invention, the scattered toner at the time of development is electrically attached to the image carrier or the conductive member to prevent contamination of the image forming apparatus main body due to the scattered toner and the image forming apparatus main body. Therefore, it can be used for a developing cartridge capable of preventing sparks and an image forming apparatus having the same.

1 is a cross-sectional view of an image forming apparatus according to an embodiment of the present invention. It is sectional drawing which shows the process cartridge which concerns on one Embodiment of this invention. (A), (b) It is a principal part expanded sectional view which shows the principal part of the process cartridge which concerns on the 1st Embodiment of this invention. It is a side view showing a transfer device, an image carrier, and a conductive member concerning a 1st embodiment of the present invention. (A), (b), (c) It is a principal part expanded side view which shows the principal part of the process cartridge which concerns on the 2nd Embodiment of this invention. It is a principal part expanded side view which shows the principal part of the process cartridge which concerns on further another embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 28 Image carrier 29 Opening / closing lid 30 Charging apparatus 34 Developing apparatus 36 Transfer apparatus 38 Cleaning apparatus 42 Cleaning blade 44 Developer collecting part 46 Process cartridge 50 Developer container 51 Opening part 52 Developing part 53 Container body 54 Agitator 55 Lid member 56 Stirring plate 58 Developing roll 60 Developer supply port 62 Blade device 64 Developing blade 66 Mounting portion 68 Conductive member 69 Tip portion 70 Insulating film (insulating member)
72 Rotating shaft 73 Transfer roll 74 Bearing member 76 Corner portion 78 Longitudinal ends on both ends

Claims (6)

A developing cartridge that can be attached to and detached from the image forming apparatus main body, and is provided with an image carrier provided to face the transfer device, and to face the image carrier, and a developer is provided on the image carrier. And a rotation direction of the developing device at a position upstream of the sheet conveying direction at a position where the image bearing member faces the transfer device, and a position at which the image bearing member faces the developing device A conductive member provided on the downstream side to which a predetermined voltage is applied; and a discharge preventing means for preventing a discharge generated between the conductive member and the transfer device, wherein the discharge preventing means includes the conductive member. A developing cartridge comprising an insulating member that covers a side of the conductive member facing the transfer device in a longitudinal direction and a leading end portion of the conductive member in a non-contact state. An image carrier on which a latent image is formed, a developing device provided so as to face the image carrier, and carrying a developer on the image carrier, and the image carrier facing the image carrier A transfer device that transfers the developer image of the carrier onto the paper, and the image carrier is located upstream of the transfer device at a position facing the transfer device, and the image carrier is the developing device. A conductive member to which a predetermined voltage is applied and a discharge preventing means for preventing a discharge generated between the conductive member and the transfer device. And the discharge preventing means is composed of an insulating member that covers a side of the conductive member facing the transfer device in a longitudinal direction and a tip of the conductive member in a non-contact state. An image forming apparatus.   3. The transfer device includes a transfer roll and a conductive bearing member that supports the transfer roll, and a predetermined voltage is applied to the transfer roll via the bearing member. Image forming apparatus.   The image forming apparatus according to claim 3, wherein the discharge preventing unit is configured such that a portion of the conductive member facing the bearing member in the longitudinal direction is separated from the transfer device more than other portions.   The image forming apparatus according to claim 4, wherein the discharge prevention unit has an arc shape at a portion facing the bearing member in the longitudinal direction of the conductive member.   The image forming apparatus according to claim 4, wherein the discharge prevention unit has an oblique shape at a portion facing the bearing member in the longitudinal direction of the conductive member.

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