Patent ID: 11899391
Assignee: CANON KABUSHIKI KAISHA
Field: Optics (Instruments)
Classification: CPC G | IPC G

Claim 0:
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.