Image forming cartridge and image forming apparatus having a photoreceptor drum that rotates at a constant velocity and is stably grounded

An image forming cartridge, comprising:

• a cartridge case;
• a photoreceptor drum disposed in said cartridge case and being removably attachable to an image forming apparatus through said cartridge case;
• a shaft disposed on a rotation center axis of said photoreceptor drum, and having opposing first and second ends that are supported, in a fixed manner, by said cartridge case;
• a drum supporting member, composed of a conductive resin, fixed internally on a side of a first end of said photoreceptor drum, and being disposed on a circumferential face of said shaft and on a side of the first end of said shaft so as to be rotatable and movable, and supporting said photoreceptor drum on said shaft so that said photoreceptor drum is rotatable;
• a conductive collar placed on the circumferential face of said shaft and near said drum supporting member so as to be rotatable and movable, said photoreceptor drum being grounded through said shaft and said conductive collar;
• first and second helical gears, said first helical gear being coaxially fixed to a second end of said photoreceptor drum and being placed on the circumferential face on a side of the second end of said shaft, said first helical gear engaging with said second helical gear, said second helical gear being for driving said image forming apparatus, and said first helical gear applying thrust to said photoreceptor drum to press said drum supporting member, by application of pressure and through said photoreceptor drum, on said collar so as to cause said drum supporting member to contact said collar;
• and
• a stopper that prevents said collar from moving on said shaft when said collar is pressed by said drum supporting member.

An image forming apparatus, comprising:

• a rotatable photoreceptor drum;
• an electrically conductive axial member that is supported and rotatable on a rotation center axis of said photoreceptor drum;
• an electrically conductive drum supporting member placed on said axial member so as to be rotatable and movable, and supporting said photoreceptor drum on said axial member so that said photoreceptor drum is rotatable;
• an electrically conductive collar placed on a circumferential face of said axial member and near said drum supporting member so as to be rotatable and movable;
• a thrust supplying unit that applies thrust to said drum supporting member, so that said drum supporting member presses on and contacts said collar;
• and
• a stopper that prevents said collar from moving on said axial member when said collar is pressed by said drum supporting member.

An image forming cartridge, comprising:

• an axial member;
• a drum supporting member placed on said axial member;
• a collar disposed on said axial member and near said drum supporting member;
• a thrust supplying unit that applies a thrust to said drum supporting member, so that said drum supporting member presses on and contacts said collar;
• and
• a stopper that prevents said collar from moving on said axial member when said collar is pressed by said drum supporting member.