Patent ID: 9342015
Filing Date: 2016-05-17
CPC Classification: G01D,G03G

Claim Text:
1. An image forming apparatus comprising: an optical detecting device mounted in a main assembly of said image forming apparatus; a movable unit, detachably mountable to the main assembly, including a rotatable member having a first light-blocking surface for blocking light and a second light-blocking surface different from the first light-blocking surface in length of a light-blocking region of said rotatable member with respect to a rotational direction of said rotatable member; and a control unit, wherein said movable unit rotates with rotation of said rotatable member so that the second light-blocking surface is movable to a first position where said optical detecting device is light-blocked and a second position where said optical detecting device is not light-blocked, and includes a locking member for locking the second light-blocking surface so that the second light-blocking surface moved to the second position is maintained in the second position, and wherein when the first light-blocking surface and the second light-blocking surface pass through a detecting portion of said optical detecting device by the rotation of said rotatable member, said control unit discriminates a state of said movable unit on the basis of a detection result of said optical detecting device.