US Patent 7804627 Image reading device

An image reading device is provided with a contact glass on which a document is to be placed; a group light source in which a plurality of point light sources are linearly arrayed; and a light source unit having the group light source mounted therein and adapted to optically scan a document surface via a contact glass with reading lights emitted from the group light source. The group light source is constructed such that at least one of the plurality of point light sources is a detecting light source for emitting a detection light toward the contact glass to detect the presence or absence of a document on the contact glass.