Patent ID: 7418214

Claim:
A state detection mechanism comprising: a supporting mechanism provided in a replaceable member attached detachably to a main apparatus; and a movable member supported by the supporting mechanism, wherein: (i) the movable member is arranged at a first predetermined position when the replaceable member is in an unused state in which the replaceable member has never been used by the main apparatus, and (ii) the movable member is arranged at a second predetermined position when the unused state is cancelled, the second predetermined position being away from the first predetermined position; and the main apparatus detects the unused state by detecting the movable member arranged at the first predetermined position, the state detection mechanism further comprising: torque transmission member for transmitting torque to the movable member by driving force from the main apparatus when the replaceable member is used in the main apparatus; and a protrusion member formed on the movable member, wherein: the supporting mechanism includes: a movable-member displacement member for (a) supporting the movable member and (b) displacing the movable member arranged at the first predetermined position to the second predetermined position by applying a pressure towards the second predetermined position to the movable member; a first restriction member for restricting the displacement by abutting to the protrusion member formed on the movable member arranged at the first predetermined position; and a second restriction member for restricting rotation of the movable member in a direction identical to a direction of rotation caused by the torque by abutting to the protrusion member formed on the movable member arranged at the first predetermined position; and said protrusion member is destroyed by load caused by the torque exerted on a section where the second restriction member and the protrusion member abut to each other, when the torque is transmitted to the movable member.