Image forming apparatus including first and second cams whose rotation angles are offset, and first and second rods that move, by rotations of first and second cams, first and second developing rollers toward and away from first and second photosensitive drums, respectively

An image forming apparatus comprising:

• a first photosensitive drum rotatable about a first drum axis extending in an axial direction;
• a second photosensitive drum rotatable about a second drum axis extending in the axial direction;
• a first developing roller rotatable about a first roller axis extending in the axial direction, the first developing roller being movable between a first contact position where the first developing roller is in contact with the first photosensitive drum and a first separated position where the first developing roller is separated from the first photosensitive drum;
• a second developing roller rotatable about a second roller axis extending in the axial direction, the second developing roller being movable between a second contact position where the second developing roller is in contact with the second photosensitive drum and a second separated position where the second developing roller is separated from the second photosensitive drum;
• a first rod for moving the first developing roller from the first contact position to the first separated position, the first rod being movable in the axial direction between a first advanced position where the first rod places the first developing roller in the first separated position and a first retracted position where the first rod allows the first developing roller to be positioned in the first contact position;
• a second rod for moving the second developing roller from the second contact position to the second separated position, the second rod being movable in the axial direction between a second advanced position where the second rod places the second developing roller in the second separated position and a second retracted position where the second rod allows the second developing roller to be positioned in the second contact position;
• a first cam rotatable about a first axis extending in the axial direction, the first cam being configured to, as the first cam rotates, shift between a first pushing state in which the first cam places the first rod in the first advanced position and a first push-released state in which the first cam allows the first rod to be positioned in the first retracted position;
• and
• a second cam rotatable about a second axis extending in the axial direction, the second cam being configured to, as the second cam rotates, shift between a second pushing state in which the second cam places the second rod in the second advanced position and a second push-released state in which the second cam allows the second rod to be positioned in the second retracted position,
• wherein the first cam comprises:
• a first disk rotatable about the first axis;
• and
• a first rib projecting from a side of the first disk in the axial direction, the first rib extending in a circumferential direction of the first disk, the first rib being in contact with the first rod when the first cam is in the first pushing state, and
• wherein the second cam comprises:
• a second disk rotatable about the second axis;
• and
• a second rib projecting from a side of the second disk in the axial direction, the second rib extending in a circumferential direction of the second disk, the second rib being in contact with the second rod when the second cam is in the second pushing state.

An image forming apparatus comprising:

• a first photosensitive drum;
• a second photosensitive drum;
• a first developing roller movable between:
• a first contact position where the first developing roller is in contact with the first photosensitive drum;
• and
• a first separated position where the first developing roller is separated from the first photosensitive drum;
• a second developing roller movable between:
• a second contact position where the second developing roller is in contact with the second photosensitive drum;
• and
• a second separated position where the second developing roller is separated from the second photosensitive drum;
• a first rod for moving the first developing roller from the first contact position to the first separated position, the first rod being movable between:
• a first advanced position where the first rod places the first developing roller in the first separated position;
• and
• a first retracted position where the first rod allows the first developing roller to be positioned in the first contact position;
• a second rod for moving the second developing roller from the second contact position to the second separated position, the second rod being movable between:
• a second advanced position where the second rod places the second developing roller in the second separated position;
• and
• a second retracted position where the second rod allows the second developing roller to be positioned in the second contact position;
• a first cam configured to, as the first cam rotates, shift between:
• a first pushing state in which the first cam places the first rod in the first advanced position;
• and
• a first push-released state in which the first cam allows the first rod to be positioned in the first retracted position,
• the first cam including:
• a first disk;
• and
• a first rib projecting from a side of the first disk and extending in a circumferential direction of the first disk, the first rib being in contact with the first rod when the first cam is in the first pushing state;
• and
• a second cam configured to, as the second cam rotates, shift between:
• a second pushing state in which the second cam places the second rod in the second advanced position;
• and
• a second push-released state in which the second cam allows the second rod to be positioned in the second retracted position,
• the second cam including:
• a second disk;
• and
• a second rib projecting from a side of the second disk and extending in a circumferential direction of the second disk, the second rib being in contact with the second rod when the second cam is in the second pushing state.

An image forming apparatus comprising:

• a photosensitive drum;
• a developing roller movable between a contact position where the developing roller is in contact with the photosensitive drum and a separated position where the developing roller is separated from the photosensitive drum;
• a rod for moving the developing roller from the contact position to the separated position, the rod being movable between an advanced position where the rod places the developing roller in the separated position and a retracted position where the rod allows the developing roller to be positioned in the contact position;
• and
• a cam configured to, as the cam rotates, shift between a pushing state in which the cam places the rod in the advanced position and a push-released state in which the cam allows the rod to be positioned in the retracted position,
• the cam including:
• a disk;
• and
• a rib projecting from a side of the disk and extending in a circumferential direction of the disk, the rib being in contact with the rod when the cam is in the pushing state.