A method of manufacturing a torsion bar includes cutting a stock torsion bar material to a desired torsion bar length to form the torsion bar. The method also includes forming a first end portion by removing material from the torsion bar to form a first annular groove extending circumferentially about the torsion bar. The method further includes forming a second end portion by removing material from the torsion bar to form a second annular groove extending circumferentially about the torsion bar.

A developing cartridge includes a coupling member provided adjacent to a first end of a casing. The coupling member is operatively connected to a developing roller, and the coupling member is rotatable about a rotational axis thereof. The coupling member includes (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 a second end of the casing and the first and second projections.

A power transmission shaft has a shaft member having, on an outer peripheral surface thereof, a male spline; a cylindrical member having, on an inner peripheral surface thereof, a female spline; and a seal member provided in a pressed state between an outer peripheral seal surface formed on the outer peripheral surface of the shaft member and an inner peripheral seal surface formed on the inner peripheral surface of the cylindrical member. The cylindrical member is spline-engaged with the shaft member by one end side of the shaft member being inserted into the cylindrical member from an other end side of the cylindrical member. Axial direction shock is absorbed by sliding of the splines. The outer peripheral seal surface is positioned at the other end side with respect to the male spline, and the inner peripheral seal surface is positioned at the other side with respect to the female spline.

A coupling member drum unit for a cartridge includes a cylindrical photosensitive drum having an axis L1 and a coupling member operatively connected to the photosensitive drum. The coupling member includes a drum flange provided at an end of the photosensitive drum, with a part of the drum flange being positioned inside of the photosensitive drum, and a connecting part operatively connected to the drum flange. The connecting part includes a cap positioned adjacent to the drum flange, an arm portion extending from the cap in a direction of the axis L1, and a projection projecting from the arm portion in a direction perpendicular to the axis L1, with the projection being movable between a first position and a second position, and with an end of the projection being closer to the axis L1 in the first position than in the second position.

A cartridge includes a photosensitive drum and a coupling member operatively connected to the photosensitive drum, with the coupling member including an arm portion and a projection projecting from the arm portion. The arm portion of the coupling member extends from a point that is upstream in the rotational direction of the photosensitive drum towards a point that is downstream in the rotation direction of the photosensitive drum.

A drum unit for a cartridge includes a cylindrical photosensitive drum having an axis L1 and a coupling member operatively connected to the photosensitive drum. The coupling member includes a first member having a cylindrical portion, a part of the first member being positioned inside of the photosensitive drum and a part of the first member being positioned outside of the photosensitive drum. The coupling member also includes a second member operatively connected to first member, the second member including a plurality of arm portions that are movable relative to the first member, with at least a part of each of the arm portions being positioned inside of the photosensitive drum and inside of the first member.

A power transmission shaft has a shaft member having, on an outer peripheral surface thereof, a male spline; a cylindrical member having, on an inner peripheral surface thereof, a female spline; and a seal member provided in a pressed state between an outer peripheral seal surface formed on the outer peripheral surface of the shaft member and an inner peripheral seal surface formed on the inner peripheral surface of the cylindrical member. The cylindrical member is spline-engaged with the shaft member by one end side of the shaft member being inserted into the cylindrical member from an other end side of the cylindrical member. Axial direction shock is absorbed by sliding of the splines. The outer peripheral seal surface is positioned at the other end side with respect to the male spline, and the inner peripheral seal surface is positioned at the other side with respect to the female spline.

A coupling member is provided for a cartridge that includes a cylindrical photosensitive drum that is rotatable about an axis. The coupling member is operatively connected to the photosensitive drum and is capable of receiving a rotational force for rotating the photosensitive drum.

A process cartridge includes a photosensitive drum and a coupling member operatively connected to the photosensitive drum, with the coupling member including an arm portion and a projection projecting from the arm portion. The arm portion of the coupling member extends from a point that is upstream in the rotational direction of the photosensitive drum towards a point that is downstream in the rotation direction of the photosensitive drum.

A cartridge includes a casing and a photosensitive drum rotatably supported by the casing, with the photosensitive drum having a first end and a second end. A coupling member is provided adjacent to the first end of the photosensitive drum, with the coupling member being operatively connected to the photosensitive drum. The coupling member includes (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.