US Patent 7667877 Document reader

A document reader includes a document feeder conveying a document along a document conveyance path, a first image reader reading an image formed on a first side of the conveyed document, and a second image reader reading an image formed on a second side of the conveyed document. Each of the first and second image readers is of an optical reduction system constituted of a light source, a mirror, a lens and an image sensor. The second image reading means is unified into a single assembly including at least the mirror, the lens and the image sensor, to be thus detachably attached, as a single unit, to the document feeding means. Thus, the document reader can clearly read the images formed on the first and second sides, it requires a short period of time from image reading to image outputting, and its maintenance is readily conducted.