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JP-7856442-B2 - Image forming apparatus

JP7856442B2JP 7856442 B2JP7856442 B2JP 7856442B2JP-7856442-B2

Inventors

  • 原 淳
  • 鉄野 修一
  • ▲高▼山 利彦
  • 小林 進介
  • 船谷 和弘

Assignees

  • キヤノン株式会社

Dates

Publication Date
20260511
Application Date
20220203
Priority Date
20210224

Claims (12)

  1. An image forming apparatus capable of performing an image forming operation to form an image on a transfer surface, A rotatable image carrier, A charging member that contacts the surface of the image carrier to form a charged portion, and charges the surface of the image carrier at the charged portion, An exposure unit that exposes the surface of the image carrier to form an electrostatic latent image on the surface of the image carrier which has been charged by the charging member, A developing member that supplies a developer charged with normal polarity to the surface of the image carrier to develop the electrostatic latent image as a developer image, A transfer member that contacts the image carrier to form a transfer portion, and in the transfer portion transfers the developer image from the image carrier to the transfer object, In the rotational direction of the image carrier, a contact portion is formed downstream of the transfer portion and upstream of the charging portion, and a brush member contacts the image carrier at the contact portion, A voltage application unit that applies voltage to the brush member, A drive unit for rotating the image carrier, The system comprises a voltage application unit and a drive unit, and a control unit that controls the voltage application unit and the drive unit. In the transfer section, after the developer image formed on the surface of the image carrier is transferred to the object to be transferred, the developer remaining on the surface of the image carrier is recovered by the developing member. The image forming apparatus is characterized in that the control unit controls the direction of the electric field generated in the first region with respect to the voltage applied to the brush member when the first region of the image carrier on which the transfer portion is formed passes the contact portion during the image forming operation, and the direction of the electric field generated in the second region of the image carrier forming the contact portion with respect to the voltage applied to the brush member before transitioning from a first operation in which the rotation speed of the image carrier is a first speed to a second operation in which the rotation speed of the image carrier is a second speed different from the first speed during a non-image forming operation different from the image forming operation.
  2. An image forming apparatus that performs an image forming operation to form an image on a transfer surface, A rotatable image carrier, A charging member that charges the surface of the image carrier in a charging section facing the image carrier, An exposure unit that exposes the surface of the image carrier, which has been charged by the charging member, to form an electrostatic latent image on the surface of the image carrier, A developing member that supplies a developer charged with normal polarity to the surface of the image carrier to develop the electrostatic latent image as a developer image, A transfer member that contacts the image carrier to form a transfer portion, and in the transfer portion transfers the developer image from the image carrier to the transfer target, In the rotational direction of the image carrier, a contact portion is formed downstream of the transfer portion and upstream of the charging portion, and a brush member contacts the image carrier at the contact portion, A first voltage application unit configured to apply only a DC voltage to the charged member, A second voltage application unit configured to apply voltage to the brush member, A drive unit for rotating the image carrier, The system comprises a first voltage application unit, a second voltage application unit, and a control unit that controls the drive unit, In the transfer section, after the developer image formed on the surface of the image carrier is transferred to the object to be transferred, the developer remaining on the surface of the image carrier is recovered by the developing member. The image forming apparatus is characterized in that the control unit controls the direction of the electric field generated in the first region with respect to the voltage applied to the brush member when the first region of the image carrier on which the transfer portion is formed passes the contact portion during the image forming operation, and the direction of the electric field generated in the second region of the image carrier forming the contact portion with respect to the voltage applied to the brush member during the transition from a first operation in which the rotation speed of the image carrier is a first speed to a second operation in which the rotation speed of the image carrier is a second speed different from the first speed during a non-image forming operation different from the image forming operation.
  3. The image forming apparatus according to claim 1 or 2, characterized in that the control unit controls the second speed to be slower than the first speed.
  4. The image forming apparatus according to claim 1 or 2, characterized in that the control unit controls the second speed to be faster than the first speed.
  5. The image forming apparatus according to claim 3, characterized in that the image carrier is controlled to rotate at the first speed during the image forming operation.
  6. The image forming apparatus according to claim 4, characterized in that the image carrier is controlled to rotate at the second speed during the image forming operation.
  7. The image forming apparatus according to claim 1 or 2, characterized in that, when the first region passes the contact portion during the image forming operation, the control unit controls the direction of the electric field generated in the first region in response to the voltage applied to the brush member so that the developer charged with the normal polarity moves from the brush member to the surface of the image carrier.
  8. The image forming apparatus according to claim 1 or 2, characterized in that the transition period from the first operation to the second operation is a transition period from a first state in which the rotation of the image carrier has stopped to a second state in which the image carrier is driven, or a transition period from the second state to the first state.
  9. The image forming apparatus according to claim 1, characterized in that the control unit controls the rotation direction of the image carrier when rotating the image carrier at the first speed and the rotation direction of the image carrier when rotating the image carrier at the second speed to be in opposite directions.
  10. The image forming apparatus according to claim 1 or 2, characterized in that the developer is a one-component developer.
  11. The image forming apparatus according to claim 2 , characterized in that the charging member is in contact with the surface of the image carrier in the charging portion.
  12. The image forming apparatus according to claim 1 or 2 , characterized in that the brush member comprises a base fabric and a thread portion consisting of a plurality of threads extending from the base fabric, and the density of the threads of the brush member is 150 kF/inch² to 350 kF/inch².

Description

This invention relates to an image forming apparatus using an electrophotographic method, such as a laser printer, copier, or facsimile. Electrophotography is a known image recording method used in image forming devices such as printers and copiers. Electrophotography uses an electrophotographic process to form an electrostatic latent image on a photosensitive drum using a laser beam. A charged colorant (hereinafter referred to as toner) is then developed onto this electrostatic latent image to form a developer image. Finally, the developer image is transferred to a recording material and fixed to form the final image. A cleanerless toner system is known in which toner that remains on the photosensitive drum without being transferred to the paper is recovered in the developing unit without the need for a cleaning member, and the toner is reused. In Patent Document 1, a cleanerless image forming apparatus is proposed in which a brush member is brought into contact with the photosensitive drum as a means of recovering any deposits adhering to the drum, since the surface of the photosensitive drum is not cleaned by a cleaning member. Japanese Patent Publication No. 2007-65580 This is a schematic cross-sectional view of the image forming apparatus in Example 1.This is a schematic diagram of the brush member in Example 1.This is a control block diagram for Example 1.This is an explanatory diagram illustrating the movement of toner passing through the brush member in Example 1.This is an explanatory diagram regarding the force acting on the brush member in Example 1.This is an explanatory diagram of the potential relationships during each operation in the printing process in Example 1.This is a timing chart for the transition from the image formation operation to the stop operation of the photosensitive drum when the photosensitive drum is started up in Example 1.This is a schematic cross-sectional view of the brush member and photosensitive drum during control execution in Example 2.This is a schematic cross-sectional view of the brush member and photosensitive drum during control execution in Example 3. The following describes, with reference to the drawings, embodiments for carrying out this invention in detail based on examples. However, the dimensions, materials, shapes, and relative arrangements of the components described in these embodiments should be appropriately modified depending on the configuration and various conditions of the device to which the invention is applied. In other words, the scope of this invention is not intended to be limited to the following embodiments.