Patent ID: 8200102

Claim:
An image forming apparatus comprising: an image bearing member which bears toner images; and a detachable unit configured to detachably attach to a main body of the image forming apparatus, wherein said detachable unit includes a first rotary member and a second rotary member, said first rotary member is configured to rotate by transmission of a driving force and said second rotary member, having a portion to be detected, is configured to separably contact with said first rotary member, and wherein said second rotary member separates from said first rotary member when said first rotary member rotates under a condition said second rotary member contacts with said first rotary member, wherein said detachable unit further includes a restricting member configured to restrict a position of said second rotary member to contact with said first rotary member and configured to keep contact between said first rotary member and said second rotary member even when said first rotary member rotates while said restricting member restricts the position of said second rotary member, wherein it is determined that said detachable unit is in an unused state when a first state, in which said portion to be detected is detected, is determined, and after the first state is determined, a second state, in which said portion to be detected is not detected, is determined, wherein after it is determined that said detachable unit is in the unused state, either the first state or the second state is maintained, and wherein the first state and the second state can be switched by selecting a contacting state and a separating state between said first rotary member and said second rotary member.