Patent ID: 7995252

Claim:
An image reading apparatus reading, as respective targets, light passing through respective images on respective documents, each document scattering and transmitting incident light, said image reading apparatus comprising: an illuminating optical system having a plurality of light sources arranged in a line along a scanning direction of a document when present in said image reading apparatus, and a light guide member for guiding rays of light from said plurality of light sources through said light guide member; a document conveying control system for conveying documents through said image reading apparatus in a subscanning direction, perpendicular to the scanning direction, and for passing the documents through a document reading position located near a light emergent surface of said light guide member from which the rays of light from said plurality of light sources emerge; an image reading optical system comprising: a plurality of image formation optical systems and a plurality of light detecting elements, which are aligned in the scanning direction, for detecting the rays of light which pass through documents, when a document is present at the document reading position, and detecting intensity of the rays of light, in the scanning direction, when no document is present at the document reading position; and a cylindrical lens array having a plurality of ridge lines, each ridge line running along the subscanning direction, the plurality of ridge lines being aligned in the scanning direction, and located in said light emergent surface of the light guide member from which the rays of light from said plurality of light sources emerge.