Patent ID: 9329558
Filing Date: 2016-05-03
CPC Classification: G03G

Claim Text:
1. An image forming apparatus comprising: a main casing; a plurality of photosensitive drums; a retaining unit configured to detachably retain the plurality of photosensitive drums and being movable between an internal position within the main casing and an external position outside of the main casing; and an endless belt configured to contact the plurality of photosensitive drums when the retaining unit is in the internal position and retains the plurality of photosensitive drums therein, wherein each of the plurality of photosensitive drums has a first flange portion, a second flange portion, and an axis extending in an axial direction, the first flange portion being positioned at an end of the photosensitive drum in the axial direction and the second flange portion being positioned at another end of the photosensitive drum in the axial direction, wherein the main casing includes a first frame and a second frame, wherein the first frame includes a plurality of first positioning recesses respectively corresponding to the plurality of photosensitive drums and respectively configured to contact the first flange portions when the retaining unit is in the internal position and retains the plurality of photosensitive drums therein, wherein the second frame includes a plurality of second positioning recesses respectively corresponding to the plurality of photosensitive drums and respectively configured to contact the second flange portions when the retaining unit is in the internal position and retains the plurality of photosensitive drums therein, wherein the retaining unit includes a plurality of pressing portions configured to exert pressure on the first flange portions of the plurality of photosensitive drums toward the first positioning recesses and exert pressure on the second flange portions of the plurality of photosensitive drums toward the second positioning recesses when the retaining unit is in the internal position and retains the plurality of photosensitive drums therein, wherein the retaining unit further includes a moving member having upper surfaces on which the pressing portions are provided, wherein each of the plurality of photosensitive drums has an axis extending in an axial direction, wherein the endless belt has a central portion and a first end and a second end in the axial direction, wherein the retaining unit has a first side wall and a second side wall, the first side wall being positioned farther from the central portion in the axial direction than the first end, the second side wall being positioned farther from the central portion in the axial direction than the second end, and wherein the moving member is positioned closer to the central portion in the axial direction than each of the first side wall and the second side wall is to the central portion in the axial direction.