Patent ID: 7751761

Claim:
An image forming apparatus comprising: a belt disposed diagonally with respect to a horizontal direction of the image forming apparatus; and a plurality of detachably mountable image forming units disposed along the belt, each of the plurality of detachably mountable image forming units including a photosensitive drum that faces at least the belt and an exposing device that forms a latent image on the photosensitive drum and a developing device that develops the latent image formed on the photosensitive drum with a toner, wherein an outer circumference of the photosensitive drum is supported by bearings, wherein each of the plurality of detachably mountable image forming units further comprises a charging device that charges the photosensitive drum, wherein within a horizontal width of the developing device of one of the plurality of detachably mountable image forming units, at least a portion of the exposing device of an adjacent one of the plurality of detachably mountable image forming units is disposed vertically, and wherein the exposing device is housed in the corresponding image forming unit, wherein each of the plurality of detachably mountable image forming units further comprises a cleaning device that cleans the toner remaining on the photosensitive drum.