Process cartridge and image forming apparatus

1. A process cartridge comprising:

a photosensitive drum;

a first casing rotatably supporting the photosensitive drum;

a developing roller configured to develop an electrostatic latent image formed on the photosensitive drum with toner;

a supplying roller configured to supply the developing roller with the toner;

a second casing rotatably supporting the developing roller and the supplying roller and containing the toner, the second casing being movable relative to the first casing so that the developing roller can move toward and away from the photosensitive drum;

a rotatable coupling including a projection and operatively connected to the supplying roller and the developing roller so that the coupling can transmit a rotational force to the supplying roller and the developing roller, at least a part of the coupling being movable in a direction perpendicular to a rotational axis of the coupling;

rotatable gears configured to transmit the rotational force from the coupling to the developing roller, and

a spring urging the at least part of the coupling toward the first casing in the direction perpendicular to the rotational axis of the coupling,

wherein, as seen along a rotational axis of the coupling, a receiving portion of the first casing that receives the at least part of the coupling urged by the spring is positioned outside an outer periphery of the photosensitive drum.

2. A process cartridge according to claim 1 , further comprising a bearing rotatably supporting the at least part of the coupling so as to be movable together with the at least part of the coupling in the direction perpendicular to the rotational axis of the coupling.

3. A process cartridge according to claim 2 , wherein the receiving portion of the first casing is configured to receive the coupling by contacting the bearing.

4. A process cartridge according to claim 2 , wherein the spring is configured to urge the at least part of the coupling via the bearing portion.

5. A process cartridge according to claim 1 , wherein the supplying roller includes a shaft, and the coupling is positioned at an end of the shaft of the supplying roller.

6. A process cartridge according to claim 1 , wherein the developing roller is capable of contacting to and separating from the photosensitive drum by movement of the second casing relative to the first casing.

7. A process cartridge according to claim 1 , wherein the coupling is an Oldham coupling.

8. A process cartridge according to claim 1 , wherein the first casing includes a drum bearing rotatably supporting the photosensitive drum, and the receiving portion is provided at the drum bearing.

9. A process cartridge according to claim 1 , wherein the coupling is configured to transmit the rotational force to the developing roller via the supplying roller and the gears.

10. A process cartridge according to claim 1 , wherein, as seen along the rotational axis of the coupling, one of the coupling and the developing roller is configured to rotate in a clockwise direction and the other of the coupling and the developing roller is configured to rotate in a counter-clockwise direction.

11. A process cartridge according to claim 1 , wherein the receiving portion of the first casing has a V shape.