US Patent 7113199 Tandem image forming device with reduced footprint

A tandem color laser printer 1 is provided with a photosensitive drum unit 15, a developing unit 14, and a scanning unit 13 for each color. The developing units 14, each including a main developer unit 25 and a toner hopper 24, and the scanning units 13, which irradiate laser beam, are alternately stacked vertically to overlap with each other in the vertical direction. This arrangement eliminates space required when arranging the developing units 14 and scanning units 13 side by side, thereby reducing the footprint of the color laser printer 1.