Cartridge and image forming apparatus

1. A cartridge removably mountable to a main body of an image forming apparatus, the cartridge comprising:

a developing unit having a developing roller configured to perform development in contact with a photosensitive drum;

two support mechanisms each configured to rotatably support the developing unit by a rotary shaft at an each end of both ends of the cartridge in a direction parallel to a rotary shaft of the developing roller; and

a biasing member provided on a same side as one of the two support mechanisms with respect to the developing unit, the biasing member being configured to apply a biasing force to the developing unit so as to bring the developing roller into contact with the photosensitive drum,

wherein, when a force against the biasing force is applied to the developing unit, the developing unit is rotated about the support shaft so that the developing roller is separated from the photosensitive drum,

wherein the one of the two support mechanisms has a bearing configured to hold the support shaft in a manner that the support shaft is slidable in a plane orthogonal to the support shaft, and

wherein, in a projection plane, onto which structural members of the cartridge are projected, orthogonal to the rotary shaft of the developing roller, an action point at which the biasing force of the biasing member acts on the developing unit is arranged in a region between a first straight line connecting a rotation center of the developing roller and a rotation center of the photosensitive drum, and a second straight line passing through the support shaft and being parallel to a slide direction of the support shaft.

2. A cartridge according to claim 1 , wherein, in the projection plane, the first straight line and the second straight line are substantially parallel to each other.

3. A cartridge according to claim 1 , wherein, in the projection plane, the first straight line and a straight line parallel to a direction in which the biasing force acts on the action point are substantially parallel to each other.

4. A cartridge according to claim 1 , wherein, in the projection plane, an angle formed by a straight line connecting the support shaft and the action point and a straight line parallel to a direction in which the biasing force acts on the action point is smaller than 90°.

5. A cartridge according to claim 1 , wherein the developing unit is provided with a receiving portion configured to receive the force against the biasing force, and

wherein, in the projection plane, a distance from the support shaft to the receiving portion is larger than a distance from the support shaft to the action point.

6. A cartridge according to claim 1 , wherein the developing unit is provided with a receiving portion configured to receive the force against the biasing force, and

wherein, in the projection plane, a distance from the support shaft to the receiving portion is larger than a distance from the support shaft to the rotation center of the developing roller.

7. A cartridge according to claim 1 , wherein, in the projection plane, the slide direction is inclined with respect to the first straight line so that the developing roller is pressed against the photosensitive drum by a component force, which acts in the slide direction, of self-weight of the developing unit.

8. A cartridge according to claim 1 , wherein a moment about the support shaft caused by self-weight of the developing unit acts in a direction in which the developing roller is separated from the photosensitive drum, and

wherein the biasing force of the biasing member has a vertically upward component force.

9. A cartridge according to claim 1 , wherein the bearing is provided with an elongated hole, and

wherein the support shaft is slidable in a longitudinal direction of the elongated hole.

10. A cartridge according to claim 1 , wherein the biasing member comprises an extension spring.

11. A cartridge according to claim 1 , further comprising a drive transmission portion configured to transmit a driving force to the developing roller, the drive transmission portion being provided on a same side as another of the two support mechanisms.

12. An image forming apparatus, comprising:

a main body; and

a cartridge removably mounted to the main body,

wherein the cartridge comprises:

a developing unit having a developing roller configured to perform development in contact with a photosensitive drum;

two support mechanisms each configured to rotatably support the developing unit by a rotary shaft at an each end of both ends of the cartridge in a direction parallel to a rotary shaft of the developing roller; and

a biasing member provided on a same side as one of the two support mechanisms with respect to the developing unit, the biasing member being configured to apply a biasing force to the developing unit so as to bring the developing roller into contact with the photosensitive drum,

wherein, when a force against the biasing force is applied to the developing unit, the developing unit is rotated about the support shaft so that the developing roller is separated from the photosensitive drum,

wherein the one of the two support mechanisms has a bearing configured to hold support shaft in a manner that the support shaft is slidable in a plane orthogonal to the support shaft, and

wherein, in a projection plane, onto which structural members of the cartridge are projected, orthogonal to the rotary shaft of the developing roller, an action point at which the biasing force of the biasing member acts on the developing unit is arranged in a region between a first straight line connecting a rotation center of the developing roller and a rotation center of the photosensitive drum, and a second straight line passing through the support shaft and being parallel to a slide direction of the support shaft.

13. An image forming apparatus according to claim 12 , wherein, in the projection plane, the first straight line and the second straight line are substantially parallel to each other.

14. An image forming apparatus according to claim 12 , wherein, in the projection plane, the first straight line and a straight line parallel to a direction in which the biasing force acts on the action point are substantially parallel to each other.

15. An image forming apparatus according to claim 12 , wherein, in the projection plane, an angle formed by a straight line connecting the support shaft and the action point and a straight line parallel to a direction in which the biasing force acts on the action point is smaller than 90°.

16. An image forming apparatus according to claim 12 , wherein the developing unit is provided with a receiving portion configured to receive the force against the biasing force, and

wherein, in the projection plane, a distance from the support shaft to the receiving portion is larger than a distance from the support shaft to the action point.

17. An image forming apparatus according to claim 12 , wherein the developing unit is provided with a receiving portion configured to receive the force against the biasing force, and

wherein, in the projection plane, a distance from the support shaft to the receiving portion is larger than a distance from the support shaft to the rotation center of the developing roller.

18. An image forming apparatus according to claim 12 , wherein, in the projection plane, the slide direction is inclined with respect to the first straight line so that the developing roller is pressed against the photosensitive drum by a component force, which acts in the slide direction, of self-weight of the developing unit.

19. An image forming apparatus according to claim 12 , wherein a moment about the support shaft caused by self-weight of the developing unit acts in a direction in which the developing roller is separated from the photosensitive drum, and

wherein the biasing force of the biasing member has a vertically upward component force.

20. An image forming apparatus according to claim 12 , wherein the bearing is provided with an elongated hole, and

wherein the support shaft is slidable in a longitudinal direction of the elongated hole.