Cartridge and image forming apparatus

1. A cartridge that is detachably mounted to a main body of an image forming apparatus and to which driving force is transferred from a driving force transfer member rotatably provided to the main body, the cartridge comprising:

a rotational body that is rotatably supported to a case of the cartridge;

a joint member that is coaxially arranged to an end portion of the rotational body in an axial direction of the joint member and has a first joint-side engagement part that is configured to be engaged to a rotational body-side engagement part provided to the end portion of the rotational body with a predetermined moving range in a rotational direction, and

a press member that presses the joint member to a position in which the predetermined moving range is secured,

wherein

the joint member has a second joint-side engagement part that is configured to be engaged with a transfer-side engagement part provided to the driving force transfer member in the rotational direction with central axes of the joint member and the driving force transfer member being substantially matched, and

wherein

while the cartridge is mounted to the main body, when the second joint-side engagement part is contacted to a part of the driving force transfer member at a position at which the central axes of the joint member and the driving force transfer member are not matched, the joint member is rotated within the predetermined range and the second joint-side engagement part is thus moved, so that the central axes of the joint member and the driving force transfer member are substantially matched and the second joint-side engagement part is engaged with the transfer-side engagement part in the rotational direction.

2. The cartridge according to claim 1 ,

wherein

two second joint-side engagement parts are provided to the joint member and the two second joint-side engagement parts sandwich the central axis of the joint member, and

wherein

two transfer-side engagement parts are provided to the driving force transfer member and the two second joint-side engagement parts are configured to be engaged to the two transfer-side engagement parts in the rotational direction.

3. The cartridge according to claim 1 ,

wherein the rotational body-side engagement part is a protrusion that protrudes from the end portion of the rotational body in a diametrically outward direction,

wherein a surface of the joint member faced to the rotational body includes a recessed portion that receives the end portion of the rotational body and the protrusion and extends in a rotational direction of the protrusion, and

wherein an end face of the recessed portion in the rotational direction functions as the first joint-side engagement part.

4. The cartridge according to claim 1 ,

wherein the press member is a plate spring that extends from the end portion of the rotational body in a diametrically outward direction, and

wherein the joint member includes a spring engagement part that is engaged with the plate spring in the rotational direction by sandwiching the plate spring with a gap from both sides of the rotational direction and permits a leading end portion of the plate spring to move in a diametrical direction.

5. The cartridge according to claim 2 , further comprising,

a lock tooth that is engaged with a tooth-missing gear provided to the main body to rotate the driving force transfer member and to thus position a direction of the transfer-side engagement part in a predetermined range.

6. A cartridge that is detachably mounted to a main body of an image forming apparatus and to which driving force is transferred from a driving force transfer member rotatably provided to the main body, the cartridge comprising:

a rotational body that is rotatably supported to a case of the cartridge, and

a joint member that is rotatably supported to the case of the cartridge and transfers driving force to the rotational body,

wherein

the joint member comprises a rotational shaft part that protrudes toward the driving force transfer member and two joint-side engagement parts that are formed to sandwich the rotational shaft part and can be engaged with two transfer-side engagement parts provided to the driving force transfer member with central axes of the joint member and the driving force transfer member being substantially matched, and

wherein

the cartridge includes a tooth-missing gear that is engaged with a lock tooth provided to the main body in mounting the cartridge to the main body to rotate the joint member and to thus position directions of the joint-side engagement parts in a predetermined range.

7. An image forming apparatus comprising a main body having a driving source and a cartridge detachably mounted to the main body,

wherein

the main body includes a driving force transfer member that is rotated as driving force is transferred thereto from the driving source,

wherein

the cartridge has:

a rotational body that is rotatably supported to a case of the cartridge,

a joint member that is coaxially arranged to an end portion of the rotational body in an axial direction of the joint member and has a first joint-side engagement part that can be engaged to a rotational body-side engagement part provided to the end portion of the rotational body with a predetermined moving range in a rotational direction, and

a press member that presses the joint member to a position in which the predetermined moving range is secured,

wherein

the driving force transfer member has a rotational shaft part that protrudes toward the joint member and a transfer-side engagement part that is provided at a position that is diametrically offset with regard to the rotational shaft part,

wherein

the joint member has a second joint-side engagement part that can be engaged with the transfer-side engagement part in the rotational direction with central axes of the joint member and the driving force transfer member being substantially matched, and

wherein

while the cartridge is mounted to the main body, when the second joint-side engagement part is contacted to a part of the driving force transfer member at a position at which the central axes of the joint member and the driving force transfer member are not matched, the joint member is rotated within the predetermined range and the second joint-side engagement part is thus moved, so that the central axes of the joint member and the driving force transfer member are substantially matched and the second joint-side engagement part is engaged with the transfer-side engagement part in the rotational direction.

8. The image forming apparatus according to claim 7 ,

wherein

two second joint-side engagement parts are provided to the joint member and the two second joint-side engagement parts sandwich the central axis of the joint member,

wherein

two transfer-side engagement parts are provided to the driving force transfer member and the two transfer-side engagement parts sandwich the rotational shaft part, and

wherein

the two second joint-side engagement parts are configured to be engaged to the two transfer-side engagement parts in the rotational direction.

9. The image forming apparatus according to claim 8 ,

wherein

the main body includes a tooth-missing gear that rotates the driving force transfer member to thus position directions of the transfer-side engagement parts in a predetermined range, and

wherein

the cartridge includes a lock tooth that is engaged with the tooth-missing gear.

10. The image forming apparatus according to claim 7 ,

wherein

the main body includes:

a cover that opens and closes an opening for attaching and detaching the cartridge; and

a return unit that, when the cover is opened, rotates the driving force transfer member in a direction along which the transfer-side engagement part is away from the second joint-side engagement part and thus returns the joint member to an initial position by pressing force of the press member.

11. An image forming apparatus comprising a main body having a driving source and a cartridge detachably mounted to the main body,

wherein

the main body includes:

a rotational member that is rotated as driving force is transferred thereto from the driving source,

a driving force transfer member that is coaxially arranged to an end portion of the rotational member in an axial direction thereof and has a first transfer-side engagement part that can be engaged to a rotational member-side engagement part provided to the end portion of the rotational member with a predetermined moving range in a rotational direction, and

a press member that presses the driving force transfer member to a position in which the predetermined moving range is secured,

wherein

the cartridge includes a joint member that is rotatably supported to a case of the cartridge and to which driving force is input from the driving force transfer member,

wherein

the driving force transfer member has two second transfer-side engagement parts that are provided to sandwich a central axis,

wherein

the joint member comprises a rotational shaft part that protrudes toward the driving force transfer member and two joint-side engagement parts that are formed to sandwich the rotational shaft part and can be engaged with the two second transfer-side engagement parts with central axes of the joint member and the driving force transfer member being substantially matched, and

wherein

the cartridge includes a tooth-missing gear that is engaged with a lock tooth provided to the main body in mounting the cartridge to the main body to rotate the joint member and to thus position directions of the joint-side engagement parts in a predetermined range.