End-side member, photoreceptor drum unit and process cartridge

1. An end-side member to be arranged at an end of a photoreceptor drum unit which is detachably attached to an image forming apparatus body, the image forming apparatus body including a drive shaft having a concave portion, wherein the concave portion is a hole having a triangular cross-sectional shape and twisted in an extending direction of an axial line of the drive shaft and a projection member projecting from the concave portion along the axis of the drive shaft, the end-side member comprising:

a convex-shaped bearing member which is engageable with and disengageable from the concave portion,

wherein a depression to be engaged with a rim of an opening of the concave portion is formed in at least a part of an outer circumferential surface of the bearing member,

wherein a hole extends along an axis of the end-side member, and

wherein the projection member that projects from the concave portion is configured to be inserted into the hole.

2. The end-side member according to claim 1 , wherein a cross section of the bearing member in a direction orthogonal to an axial line of the bearing member has a polygonal shape,

wherein the polygonal shape is a hexagonal shape,

wherein the depression includes a first inclined surface, a bottom surface, and a second inclined surface in this order in a direction along the axial line of the bearing member from a root side toward a tip end side of the bearing member, and

wherein at least one of the following equations (1) to (5) is satisfied:

0.1≦ L 1 /L≦ 0.85  (1);

0≦ L 3 /L≦ 0.65  (2);

0.01≦ d/L≦ 0.4  (3);

1°≦θ 1 ≦90°  (4); and

1°≦θ 2 ≦90°  (5),

where L (mm) represents a length in an axial direction of the bearing member, L 1 (mm) represents a distance from a root of the bearing member to an end of the depression at the root-side of the bearing member, L 3 (mm) represents a distance of the bottom surface along the axial direction of the bearing member, d (mm) represents a depth of the depression, θ 1 (°) represents an inclination angle of the first inclined surface with respect to the direction along the axial direction of the bearing member, and θ 2 (°) represents an inclination angle of the second inclined surface with respect to the direction along the axial line of the bearing member.

3. The end-side member according to claim 1 , wherein

a depth of the depression becomes shallower in a direction along an outer circumferential direction of the bearing member.

4. The end-side member according to claim 1 , wherein

a cross section including the deepest part of the depression among cross sections in a direction orthogonal to the axial line of the bearing member has a shape by which at least all three sides of the cross section including the deepest part of the depression are overlapped with a part of a rim formed at an opening of the concave portion so as to coincide with the part of the rim.

5. A photoreceptor drum unit comprising:

a photoreceptor drum; and

the end-side member as defined in claim 1 , which is arranged on at least one end of the photoreceptor drum.

6. A process cartridge comprising:

the photoreceptor drum unit as defined in claim 5 ;

a charging roller which charges the photoreceptor drum in the photoreceptor drum unit;

a developing roller which develops an electrostatic latent image on the photoreceptor drum; and

a case body which accommodates the photoreceptor drum, the charging roller, and the developing roller.

7. The end-side member according to claim 1 , wherein the triangular cross-sectional shape of the concave portion has arc shaped tips.