Patent ID: 7650098

Claim:
An image forming apparatus comprising: an outer frame; a photosensitive unit disposed in the outer frame, the photosensitive unit comprising: a plurality of photosensitive drums, each of the plurality of photosensitive drums having an axis extending in a first direction, one axial end and another axial end, the plurality of photosensitive drums being juxtaposed in a second direction perpendicular to the first direction; a first supporting shaft provided on the one axial end of each of the plurality of photosensitive drums; a second supporting shaft provided on the another axial end of each of the plurality of photosensitive drums, the first support shaft and the second support shaft rotatably supporting each of the plurality of photosensitive drums; and a drum gear provided on the one axial end of each of the plurality of photosensitive drums and rotatable together with each of the plurality of photosensitive drums, a drum drive gear rotatably supported on the outer frame and meshingly engaged with the drum gear to rotate the drum gear, the drum drive gear being configured to apply a pushing force to the drum gear, the photosensitive drum, the first supporting shaft and the second supporting shaft in the second direction when the drum drive gear drives the drum gear; a first positioning portion provided in the outer frame, the first supporting shaft and the second supporting shaft provided on one of the plurality of photosensitive drums being brought into contact with the first positioning portion by the pushing force, a position of the first supporting shaft and the second supporting shaft provided on the one of the plurality of photosensitive drums in the second direction with respect to the outer frame being determined by contacting the first supporting shaft and the second supporting shaft to the first positioning portion; and a second positioning portion provided in the outer frame and supporting two of the first supporting shafts and two of the second supporting shafts provided on two of the plurality of the photosensitive drums, a position of the two of the first supporting shafts and the two of the second supporting shafts in a third direction perpendicular to both the first direction and the second direction with respect to the outer frame being determined by supporting the two of the first supporting shafts and the two of the second supporting shafts on the second supporting portion.