Drum unit, cartridge and coupling member

1. A cartridge comprising:

a casing;

a photosensitive drum rotatably supported by the casing, the photosensitive drum having a first end and a second end; and

a coupling member provided adjacent to the first end of the photosensitive drum, the coupling member being operatively connected to the photosensitive drum, the coupling member being rotatable about a rotational axis thereof, and the coupling member including (i) a cylindrical portion, (ii) a first projection at least partially positioned inside of the cylindrical portion, (iii) a second projection at least partially positioned inside of the cylindrical portion, (iv) an elastically movable projection at least partially positioned inside of the cylindrical portion, and (v) a wall extending in a direction perpendicular to the rotational axis and positioned between the second end of the photosensitive drum and the first and second projections,

wherein, along a line perpendicular to the rotational axis of the coupling member, the first projection is open to the rotational axis of the coupling member, and

wherein, along a line perpendicular to the rotational axis of the coupling member, the second projection is open to the rotational axis of the coupling member.

2. A cartridge according to claim 1 , wherein, along a line perpendicular to the rotational axis of the coupling member the the movable projection is open to the rotational axis of the coupling member.

3. A cartridge according to claim 1 , wherein the movable projection is movable such that a distance between the movable projection and the first and second projections is changeable.

4. A cartridge according to claim 1 , wherein the movable projection is movable between a first position and a second position, with a distance between the rotational axis of the coupling member and an end of the movable projection being shorter when the movable projection is in the first position than when the movable projection is in the second position.

5. A cartridge according to claim 4 , wherein the movable projection is biased toward the first position.

6. A cartridge according to claim 1 , wherein the first projection, the second projection, and the movable projection are at least partially positioned inside of the photosensitive drum.

7. A cartridge according to claim 1 , wherein as seen in a direction of the rotational axis of the coupling member, the first and second projections are positioned in one half section of the inside of the cylindrical portion and the movable projection is positioned in a second half section of the inside of the cylindrical portion.

8. A process cartridge comprising:

a casing;

a photosensitive drum rotatably supported by the casing, the photosensitive drum having a first end and a second end;

toner contained in the casing;

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

a coupling member provided adjacent to the first end of the photosensitive drum, the coupling member being operatively connected to the photosensitive drum, the coupling member being rotatable about a rotational axis thereof, and the coupling member including (i) a cylindrical portion, (ii) a first projection at least partially positioned inside of the cylindrical portion, (iii) a second projection at least partially positioned inside of the cylindrical portion, (iv) an elastically movable projection at least partially positioned inside of the cylindrical portion, and (v) a wall extending in a direction perpendicular to the rotational axis and positioned between the second end of the photosensitive drum and the first and second projections,

wherein, along a line perpendicular to the rotational axis of the coupling member, the first projection is open to the rotational axis of the coupling member, and

wherein, along a line perpendicular to the rotational axis of the coupling member, the second projection is open to the rotational axis of the coupling member.

9. A process cartridge according to claim 8 , wherein, along a line perpendicular to the rotational axis of the coupling member the the movable projection is open to the rotational axis of the coupling member.

10. A process cartridge according to claim 8 , wherein the movable projection is movable such that a distance between the movable projection and the first and second projections is changeable.

11. A process cartridge according to claim 8 , wherein the movable projection is movable between a first position and a second position, with a distance between the rotational axis of the coupling member and an end of the movable projection being shorter when the movable projection is in the first position than when the movable projection is in the second position.

12. A process cartridge according to claim 11 , wherein the movable projection is biased toward the first position.

13. A process cartridge according to claim 8 , wherein the first projection, the second projection, and the movable projection are at least partially positioned inside of the photosensitive drum.

14. A process cartridge according to claim 8 , wherein as seen in a direction of the rotational axis of the coupling member, the first and second projections are positioned in one half section of the inside of the cylindrical portion and the movable projection is positioned in a second half section of the inside of the cylindrical portion.

15. A drum unit for a cartridge, the drum unit comprising:

a photosensitive drum having a first end and a second end; and

a coupling member provided adjacent to the first end of the photosensitive drum, the coupling member being operatively connected to the photosensitive drum, the coupling member being rotatable about a rotational axis thereof, and the coupling member including (i) a cylindrical portion, (ii) a first projection at least partially positioned inside of the cylindrical portion, (iii) a second projection at least partially positioned inside of the cylindrical portion, (iv) an elastically movable projection at least partially positioned inside of the cylindrical portion, and (v) a wall extending in a direction perpendicular to the rotational axis and positioned between the second end of the photosensitive drum and the first and second projections,

wherein, along a line perpendicular to the rotational axis of the coupling member, the first projection is open to the rotational axis of the coupling member, and

wherein, along a line perpendicular to the rotational axis of the coupling member, the second projection is open to the rotational axis of the coupling member.

16. A drum unit according to claim 15 , wherein, along a line perpendicular to the rotational axis of the coupling member the movable projection is open to the rotational axis of the coupling member.

17. A drum unit according to claim 15 , wherein the movable projection is movable such that a distance between the movable projection and the first and second projections is changeable.

18. A drum unit according to claim 15 , wherein the movable projection is movable between a first position and a second position, with a distance between the rotational axis of the coupling member and an end of the movable projection being shorter when the movable projection is in the first position than when the movable projection is in the second position.

19. A drum unit according to claim 18 , wherein the movable projection is biased toward the first position.

20. A drum unit according to claim 15 , wherein the first projection, the second projection, and the movable projection are at least partially positioned inside of the photosensitive drum.

21. A drum unit according to claim 15 , wherein as seen in a direction of the rotational axis of the coupling member, the first and second projections are positioned in one half section of the inside of the cylindrical portion and the movable projection is positioned in a second half section of the inside of the cylindrical portion.