Image forming apparatus, discrimination system and unit discrimination method of image forming apparatus

A discrimination system comprising:

• an apparatus body comprising an image forming portion configured to form an image, and a detection portion configured to turn in a first state and a second state and configured to output a detection signal corresponding to the first state and the second state;
• and
• a controller configured to discriminate whether a unit attached to the apparatus body is a first unit or a second unit,
• wherein the first unit is detachably mounted to the apparatus body and comprises a first unit body, a first cam rotatably supported on the first unit body and configured to position at least at two rotation positions, a first unit movement member configured to move with respect to the first unit body by rotation of the first cam, and a first unit flag member movably supported with respect to the first unit movement member and turning the detection portion to the first state and to the second state by movement of the first unit movement member,
• the second unit is detachably mounted to the apparatus body and comprises a second unit body, a second cam rotatably supported on the second unit body and configured to position at least at two rotation positions, a second unit movement member configured to move with respect to the second unit body by rotation of the second cam, and a second unit flag member movably supported with respect to the second unit movement member and turning the detection portion to the first state and to the second state by movement of the second unit movement member, and
• the controller is configured to discriminate whether a unit attached to the apparatus body is the first unit or the second unit based on a difference between a detection pattern of the detection signal output by the detection portion while the first cam or the second cam rotates once.

A unit discrimination method of an image forming apparatus comprising an apparatus body capable of having a plurality of types of units attached thereto, and a detection portion configured to turn in a first state and a second state and configured to output a detection signal corresponding to the first state and the second state, the unit discrimination method comprising:

• a rotation step of rotating a cam once provided on a unit attached to the apparatus body once;
• a detection step of detecting a detection signal output by the detection portion turned in the first state and the second state in the rotation step, wherein a detection pattern of the detection signal output by the detection portion while the cam rotates once differs according to a type of the unit;
• and
• a discrimination step of discriminating the type of the unit based on the detection pattern detected during the detection step.