Patent ID: 6903757

Claim:
An image forming device comprising: a plurality of image forming units, each of the plurality of image forming units being provided for each of a plurality of colors, the plurality of image forming units being aligned vertically; and a casing that accommodates the plurality of image forming units, each of the plurality of image forming units comprising: a photosensitive member; an exposing device that exposes the photosensitive member to a laser beam to form electrostatic latent images thereon; and a developing device that develops the electrostatic latent images formed on the photosensitive member using developer to form developer images, wherein the developing device and the exposing device are aligned to overlap with each other in a vertical direction, when the casing is disposed in an orientation in which the casing is intended to be used; wherein the exposing device includes: a laser beam emitting unit that emits a laser beam; a polygon mirror that reflects the laser beam emitted by the laser beam emitting unit; and a lens through which the laser beam reflected by the polygon mirror passes; and wherein the polygon mirror, the lens, and a corresponding portion of the photosensitive member that is irradiated by the laser beam are arranged on a same plane, the laser beam that has passed through the lens being directly irradiated onto the corresponding portion of the photosensitive member.