A sheet size setting device for giving information for identifying a sheet size to a sheet size detector, the sheet size setting device comprising:
- a housing including a first mounting section having a first space, and a second mounting section adjacent to the first mounting section and having a second space;
- a first rotary member having a cylindrical shape, and supported on the first mounting section, and rotatable around and slidably movable along a first axis extending to the second space in the first space
- an engaging portion provided in the housing;
- a biasing member;
- a second rotary member supported on the second mounting section rotatably around a second axis parallel to the first axis;
- and
- an assisting mechanism,
- wherein the first rotary member includes a first region, a second region, and a third region along the first axis, the first rotary member further including:
- a plurality of detected portions to be detected by the sheet size detector, the plurality of detected portions being disposed in the first region, and in a circumferential direction of the first rotary member;
- a plurality of engaged portions to be selectively engaged with the engaging portion, the plurality of engaged portions being disposed in the second region, and corresponding to the plurality of detected portions in the circumferential direction of the first rotary member;
- and
- a first gear portion disposed in the third region for receiving a driving force for rotation around the first axis,
- wherein the housing includes:
- a first supporting plate defining one end of the first space in the first axis direction of the first rotary member;
- a second supporting plate disposed oppositely to the first supporting plate to define the other end of the first space in the first axis direction, and dividing the first space from the second space, the second supporting plate having a bearing opening allowing the first gear portion of the first rotary member to pass therethrough, and the second supporting plate supporting the first rotary member with the first supporting plate,
- wherein the engaging portion is disposed on the second supporting plate in such a way as to face the engaged portion, the engaging portion being operable to engage with one of the plurality of engaged portions in the rotation of the first rotary member around the first axis to thereby restrict the rotation of the first rotary member,
- wherein the biasing member is disposed between the first supporting plate and the first rotary member for biasing the first rotary member in a direction of permitting the engaged portion to engage with the engaging portion,
- wherein the second rotary member includes:
- a second gear portion disposed on the second axis and engaged with the first gear portion;
- and
- a disk portion for rotating the second gear portion,
- wherein the second rotary member is rotated in a specific direction around the second axis to rotate the first rotary member to set a sheet size, and
- wherein the assisting mechanism applies a moving force to the first rotary member in the axial direction with the rotation of the second rotary member around the second axis so that the engaged portion disengages from the engaging portion against the biasing force of the biasing member.