Patent ID: 6693658
Filing Date: 2004-02-17
Classification: G02B,H04N

Abstract:
A light beam scanning apparatus comprising:a light emitting device which generates a light beam; a light beam scanning member which scans said light beam against a scanned surface so that said light beam output from said light emitting device scans on said scanned surface in a horizontal scan direction; a sensor which is arranged on said scanned surface or a position equivalent to said scanned surface, detects said light beam scanned by said light beam scanning member, and outputs an electric signal; a mirror which changes a passage position for a vertical scan direction of said light beam scanned by said light beam scanning member in said horizontal scan direction; a detection section which detects a maximum value for the electric signal output from said sensor in response to said light beam with its passage position gradually moved by said mirror; and a control section which determines a normal light beam when said maximum value detected by said detection section is greater than a specified reference value, and determines a defocused light beam when the maximum value is smaller than said specified reference value.