Image forming apparatus including drawer

An image forming apparatus comprising:

• a main housing including a first contact member;
• a first drum cartridge including a first photosensitive drum;
• and
• a drawer unit configured such that the first drum cartridge is mounted thereon, the drawer unit being configured to move in a moving direction between an internal position at which the drawer unit is located inside the main housing and an external position at which the drawer unit is located outside the main housing, the drawer unit including:
• a drawer frame;
• a first exposure head configured to move between a first adjacent position at which the first exposure head is adjacent to the first photosensitive drum and a first spaced position at which the first exposure head is spaced farther away from the first photosensitive drum than at the first adjacent position;
• and
• a second contact member that is a part of the drawer unit other than the first exposure head,
• the first exposure head being configured to move from the first adjacent position to the first spaced position due to a contact between the first contact member and the second contact member when the drawer unit moves from the internal position to the external position,
• wherein the first contact member includes a rack gear,
• wherein the drawer unit includes a spring configured to press the first exposure head from the first spaced position toward the first adjacent position,
• wherein the second contact member is a gear configured to rotate by engaging the rack gear when the drawer unit moves between the internal position and the external position;
• wherein the gear includes a cam,
• wherein, when the drawer unit moves from the internal position to the external position, the cam is configured to move to a pressing position at which the cam causes the first exposure head to be located at the first spaced position, due to rotation of the gear, and
• wherein, when the drawer unit moves from the external position to the internal position, the cam is configured to move to a pressing release position at which pressing against the first exposure head is released, due to rotation of the gear.