Patent ID: 6469730
Filing Date: 2002-10-22
Classification: B41J,H04N

Abstract:
A light beam scanning apparatus comprising:a first light beam generating unit for generating a first light beam; a second light beam generating unit for generating a second light beam; a scanning unit for reflecting said first and second light beams generated by said first and second light beam generating units to a scanning surface and causing said first and second light beams to scan said scanning surface; a first light beam sensing unit, located equivalent of said scanning surface, for sensing one of said first and second light beams caused to scan the scanning surface simultaneously by said scanning unit; a clock generating unit for generating a clock which is synchronized with an output of said first light beam sensing unit; a first image formation area setting unit for determining an image formation area of said first light beam on the basis of the clock output by said clock generating unit; a second image formation area setting unit for determining an image formation area of said second light beam on the basis of the clock output by said clock generating unit; a second light beam sensing unit, located downstream of said first light beam sensing unit in a light beam scanning direction, for sensing said first light beam that scans the image formation area determined by said first image formation area setting unit and said second light beam that scans the image formation area determined by said second image formation area setting unit; a first recognition unit for recognizing a positional relationship between said second light beam sensing unit and the image formation area of said first light beam determined by said first image formation area setting unit, based on a sensing result obtained by said second light beam sensing unit when said first light beam scans the image formation area determined by said first image formation area setting unit; a second recognition unit for recognizing a positional relationship between said second light beam sensing unit and the image formation area of said second light beam determined by said second image formation area setting unit, based on a sensing result obtained by said second light beam sensing unit when said second light beam scans the image formation area determined by said second image formation area setting unit; and a control unit, for controlling said first and second image formation area setting units so that the image formation areas of said first and second light beams will be the same on the scanning surface of said first and second light beams, based on a recognition result obtained by said first and second recognition units.