Image forming apparatus

1. An image forming apparatus, comprising:

a main body; and

a cartridge configured to be detachably attached to the main body, the cartridge comprising:

a photosensitive member configured to carry an image formed in a developer agent thereon,

a movable mechanism, and

a developer cartridge comprising a developer roller configured to supply the developer agent to the photosensitive member,

wherein the movable mechanism comprises a first movable member and a second movable member, the first movable member being configured to move between a roller contacting position, at which the first movable member causes the developer roller to contact the photosensitive member, and a roller spaced position, at which the first movable member causes the developer roller to be spaced from the photosensitive member,

wherein the developer cartridge comprises a driving coupling and a gear,

wherein the main body is configured to apply a driving force to the driving coupling, and the driving coupling is configured to transmit the driving force to the gear,

wherein the gear comprises a projection configured to contact the second movable member, and the gear is configured to move, in accordance with the driving force, between a projection contacting position, at which the projection contacts the second movable member, and a projection spaced position, at which the projection is spaced from the second movable member,

wherein the movable mechanism is configured to shift between a first state and a second state,

wherein the main body comprises a detectable member configured to detect a state of the movable mechanism between the first state and the second state,

wherein the detectable member is configured to detect the second state when the first movable member is located at the roller separated position irrespective of a position of the gear,

wherein the detectable member is configured to also detect the second state when the gear is located at the projection contacting position irrespective of a position of the first movable member, and

wherein the detectable member is configured to detect the first state when the first movable member is located at the roller contacting position and the gear is located at the projection separated position.

2. The image forming apparatus according to claim 1 ,

wherein the second movable member is configured to be moved along with the first movable member moving between the roller contacting position and the roller spaced position;

wherein the detectable member detects the state of the movable mechanism based on a position of the second movable member; and

wherein the second movable member is movable between an undetectable position, at which the second movable member is undetectable by the detectable member when the first movable member is located at the roller contacting position, and a detectable position, at which the second movable member is detectable by the detectable member when the first movable member is located at the roller spaced position.

3. The image forming apparatus according to claim 2 ,

wherein, when located at the undetectable position, the second movable member is spaced apart from the first movable member; and

wherein, when located at the detectable position, the second movable member is in contact with the first movable member.

4. The image forming apparatus according to claim 3 , further comprising:

a control device; and

a plurality of cartridges including the cartridge, each of the plurality of cartridges having a same configuration as the cartridge,

wherein a photosensitive drum of each of the plurality of cartridges has one of a first specification and a second specification, at least one of the plurality of cartridges having a photosensitive drum of the first specification,

wherein a second movable member, which corresponds to a cartridge having the photosensitive drum of the first specification, has a first shape, and contacts a corresponding first movable member when the first movable member is located at the roller spaced position,

wherein a second movable member, which corresponds to a cartridge having the photosensitive drum of the second specification, has a second shape, and contacts a corresponding first movable member when the first movable member is located at the roller spaced position or the roller contacting position,

wherein the control device is configured to determine a specification of each photosensitive drum of the plurality of cartridges based on the state of a corresponding movable mechanism detected by a corresponding detectable member.

5. The image forming apparatus according to claim 2 ,

wherein a movable amount for the second movable member to move between the undetectable position and the detectable position is greater than a movable amount for the first movable member to move between the roller contacting position and the roller spaced position.

6. The image forming apparatus according to claim 1 ,

wherein the detectable member comprises an optical sensor.

7. The image forming apparatus according to claim 1 ,

wherein the second movable member is configured to be engageable with the first movable member, and to be moved along with the first movable member moving between the roller contacting position and the roller spaced position;

wherein the second movable member is movable between a non-engageable position, at which the second movable member is non-engageable with the first movable member when the first movable member is located at the roller contacting position, and an engageable position, at which the second movable member is engageable with the first movable member when the first movable member is located at the roller spaced position; and

wherein the detectable member detects the state of the movable mechanism based on detection of the second movable member; and

wherein the detectable member detects the second movable member when the second movable member is located at the engageable position, and the detectable member does not detect the second movable member when the second movable member is located at the non-engageable position.

8. The image forming apparatus according to claim 7 ,

wherein the detectable member comprises an optical sensor;

wherein the second movable member is configured to pivot about a pivot axis to move between the non-engageable position and the engageable position; and

wherein the pivot axis of the second movable member extends along a direction orthogonal to detectable light emitted in the optical sensor.

9. The image forming apparatus according to claim 1 , further comprising:

a cover attached to the main body, the cover being movable between an open position and a closed position; and

a control device,

wherein the developer cartridge is configured to be detachably attached to the cartridge,

wherein, when the cover is moved to the closed position, the control device controls the main body such that the main body outputs the driving force to move the gear, and

wherein the control device is configured to determine newness of the developer cartridge based on the state of the movable mechanism detected by the detectable member.