Image forming apparatus

Patent metadata

Field	Value
Publication number	US-11899391-B2
Application number	US-202318192824-A
Country	US
Kind code	B2
Filing date	Mar 30, 2023
Priority date	Apr 1, 2022
Publication date	Feb 13, 2024
Grant date	Feb 13, 2024

Abstract

An image forming apparatus capable of forming images in mono-color and a plurality of colors includes first and second image forming units and a control unit. The image forming unit includes a rotatable image bearing member, a rotatable developing member that contacts the image bearing member to supply a developer to the surface thereof, and a developer supply member that supplies the developer to the developing member. The control unit switches between an image forming operation of forming an image on the image bearing member surface and a cleaning operation of removing an attached matter on the image bearing member surface with the developing member by controlling a voltage applied to the developing member and a voltage applied to the developer supply member.

First claim

What is claimed is:

1. An image forming apparatus comprising a first image forming unit corresponding to a first color and a second image forming unit corresponding to a second color other than the first color,
wherein the first image forming unit includes: a rotatable first image bearing member, a surface of which is exposed to light to form an electrostatic latent image on the surface of the first image bearing member; a rotatable first developing member that contacts the first image bearing member to supply a developer to the surface of the first image bearing member and that rotates at a rotational speed different from a rotational speed of the first image bearing member; and a first developer supply member that supplies the developer to the surface of the first developing member, and
wherein the second image forming unit includes: a rotatable second image bearing member, a surface of which is exposed to light to form an electrostatic latent image on the surface of the second image bearing member; a rotatable second developing member that contacts the second image bearing member to supply a developer to the surface of the second image bearing member and that rotates at a rotational speed different from a rotational speed of the second image bearing member; and a second developer supply member that supplies the developer to the surface of the second developing member,
the image forming apparatus further comprising:
a control unit configured to control a development voltage applied to the first developing member and the second developing member and a supply voltage applied to the first developer supply member and the second developer supply member, the control unit being capable of executing an image forming operation of forming a developer image on the surface of the first image bearing member by supplying the developer to the latent electrostatic image formed on the surface of the first image bearing member from the first developing member and of forming a developer image on the surface of the second image bearing member by supplying the developer to the latent electrostatic image formed on the surface of the second image bearing member from the second developing member, and a cleaning operation which is other than the image forming operation and by which an attached matter that has attached to the surface of the image bearing member is removed by the developing member, wherein
the image forming operation includes a first image forming operation of forming an image by using only the first image forming unit, and a second image forming operation of forming an image by using the first image forming unit and the second image forming unit;
the first image forming unit can move the first developing member between a contact state in which the first developing member and the first image bearing member are in contact with each other and a separation state in which the first developing member and the first image bearing member are separated from each other, the second image forming unit can move the second developing member between a contact state in which the second developing member and the second image bearing member are in contact with each other and a separation state in which the second developing member and the second image bearing member are separated from each other, and, the image forming operation and the cleaning operation are performed in the contact state; and
the control unit is configured to perform control to execute the cleaning operation after the second image forming operation in a case of switching from the second image forming operation to the first image forming operation;
to perform control to execute the cleaning operation in the first image forming unit and the second image forming unit without causing the second developing member that is in the contact state with the second image bearing member to make a transition to the separation state in the second image forming unit; and
to perform control to cause the second developing member to make a transition to the separation state in the second image forming unit after the cleaning operation, and to execute the first image forming operation in the first image forming unit.

2. The image forming apparatus according to claim 1 , wherein
the control unit is configured to make the time of the cleaning operation in the first image forming unit shorter than the time of the cleaning operation in the second image forming unit in the cleaning operations executed in the first image forming unit and the second image forming unit after the second image forming operation in a case of switching from the second image forming operation to the first image forming operation.

3. The image forming apparatus according to claim 1 , wherein:
the control unit is configured to execute the second image forming operation in the first image forming unit and the second image forming unit after executing the cleaning operation in the first image forming unit and causing the second developing member to make a transition to the contact state in the second image forming unit, without causing the first developing member that is in the contact state with the first image bearing member to make a transition to the separation state in the first image forming unit at the time of the first image forming operation in a case of switching from the first image forming operation to the second image forming operation.

4. The image forming apparatus according to claim 3 , wherein:
the control unit is configured to perform the cleaning operation in the first image forming unit and the second image forming unit after executing the second image forming operation, and in the first image forming unit, the time of the cleaning operation executed when switching from the first image forming operation to the second image forming operation is shorter than the time of the cleaning operation executed after the second image forming operation.

5. The image forming apparatus according to claim 1 , wherein:
the control unit is configured to execute the cleaning operation in the first image forming unit and the second image forming unit after the second image forming operation in a case of switching from the first image forming operation to the second image forming operation, and the time of the cleaning operation in the first image forming unit is longer than the time of the cleaning operation in the second image forming unit.

6. The image forming apparatus according to claim 1 , wherein:
a positional relationship of the first developing member in the first image forming unit with respect to the first image bearing member and a positional relationship of the second developing member in the second image forming unit with respect to the second image bearing member are switched among: (i) a state in which the first developing member is in contact with the first image bearing member in the first image forming unit and the second developing member is in contact with the second image bearing member in the second image forming unit, (ii) a state in which only the first developing member of the first image forming unit is in contact with the first image bearing member, and (iii) a state in which the first developing member is separated from the first image bearing member in the first image forming unit and the second developing member is separated from the second image bearing member in the second image forming unit.

7. The image forming apparatus according to claim 1 , further comprising:
an intermediate transfer member, which is an endless belt and to which the developer images formed in the first image forming unit and the second image forming unit are transferred while the intermediate transfer member is rotated, wherein
the first image forming unit is arranged downstream of

Assignees

• Canon Kk

Inventors

• Kume Takao

Classifications

• G03G21/0064 Primary

  using the developing unit, e.g. cleanerless or multi-cycle apparatus · CPC title

• G03G15/0813

  characterised by means in the developing zone having an interaction with the image carrying member, e.g. distance holders · CPC title

• G03G15/095

  Removing excess solid developer {, e.g. fog preventing} · CPC title

• G03G15/5004

  Power supply control, e.g. power-saving mode, automatic power turn-off · CPC title

• G03G2215/00025

  Machine control, e.g. regulating different parts of the machine · CPC title