Abstract: An image forming apparatus providing frame support for an optical scanning unit and related image forming elements is formed of resin containing less than 10% glass fibers and includes reinforcement formations having a continuous hollow interior to increase rigidity while reducing weight. The apparatus is substantially box-like with ribbed surface for mounting a laser beam scanning unit and upright walls for mounting a drive unit are formed with ribs extending from thick wall portions.

Abstract: A sheet feeder of the present invention allows a sheet feed cassette having a small capacity and a sheet feed cassette having a large capacity to be installed to a sheet feed unit by making not only members for connection between each sheet feed cassette and the sheet feed unit but also their positional relationship in common.

Abstract: An exhaust device 10, which is arranged on the upper surface of the main unit frame 11 of an electronic copying machine, a printer, or the like, is constructed with a louver 15 having a section in an approximately spherical shape, with an air exhaust fan 18 arranged in the space under the louver 15. Moreover, the louver 15 mentioned above is provided with a large number of slits 16 formed along its arc-shaped structure, and, with these slits 16, the exhaust device can secure an exhaust port even when another object is placed on the louver 15 mentioned above because the slits 16 will not be obstructed completely even in such a case.