Document size detecting device.

摘要

A document size detecting device according to the invention is adapted to be mounted in an image forming device for a copying machine or the like, comprising an arm (3) adapted to be folded and unfolded in operative association with the forward and backward movements, respectively, of the optical section (11, 12) of the image forming device, and a plurality of optical sensors (37) attached to the arm (3) at predetermined positions thereon corresponding to various format sizes of documents.