Image-forming apparatus including cam and cam follower for moving developing roller toward and away from photosensitive drum

An image-forming apparatus comprising:

• a photosensitive drum;
• a developing roller rotatable about an axis extending in an axial direction and movable between a contact position in contact with the photosensitive drum and a separated position away from the photosensitive drum;
• a cam rotatable in a prescribed rotational direction to move the developing roller between the contact position and the separated position, the cam having a cam surface comprising;
• a first holding surface;
• a second holding surface;
• a first guide surface connecting the second holding surface to the first holding surface in the prescribed rotational direction;
• and
• a second guide surface connecting the first holding surface to the second holding surface in the prescribed rotational direction;
• a switching mechanism configured to control the rotation of the cam;
• a cam follower in contact with the cam surface, the cam follower being movable between:
• an operating position for positioning the developing roller at the separated position;
• and
• a standby position for positioning the developing roller at the contact position,
• the cam follower in contact with the first holding surface being held at the standby position,
• the cam follower in contact with the second holding surface being held at the operating position,
• the first guide surface being configured to guide the cam follower to move from the first holding surface to the second holding surface in accordance with rotation of the cam in the prescribed rotational direction,
• the second guide surface being configured to guide the cam follower to move from the second holding surface to the first holding surface in accordance with the rotation of the cam in the prescribed rotational direction;
• and
• a controller configured to provide control to the switching mechanism to control the rotation of the cam,
• in a case where the developing roller is maintained at the contact position after being moved from the separated position, the controller being configured to control the switching mechanism to cause the cam:
• to rotate to move the cam follower from the second holding surface to the first holding surface through the second guide surface;
• and
• to stop rotating to hold the cam follower in contact with the first guide surface and at a position closer to the first holding surface than to the second holding surface in the axial direction.