| 摘要 |
PURPOSE:To realize longevity, miniaturization and high sensitivity without the need of fitting sensors over a wide range by equipping a light projecting system from which three beams are emitted to detection positions arranged in a row, and a light receiving system having light receiving elements to which their reflection lights are fed through a large aperture lens. CONSTITUTION:Three document detection points 20 are arranged on the same straight line so that each of document detection point intervals (x) on a document 17 surface may become 30-40mm, and projected beams 18 from a grating 14 are irradiated to these document detection points 20, and document detection point intervals (x) become the spot intervals of projected beams irradiated to the document 17 surface. Thus, light from a light emitting element 12 is fed to the grating 14 through a light projecting lens 13, and the grating 14 projects three beams 18 to the document 17. And, reflection lights 19 from three document detection points 20 facing the document 17 are respectively made incident on corresponding light receiving elements 16 through a light receiving lens 15 of a large aperture. |
