Patent ID: 6344866
Filing Date: 2002-02-05
Classification: G02B

Abstract:
A light beam scanner unit comprising:generating means for generating a light beam; scanner means for reflecting the light beam from the generating means toward a scanning surface to scan the scanning surface by the light beam; timing sensor means for sensing a passing timing of the light beam scanning the scanning surface with the scanner means to output an output signal; digitizing means for digitizing the output signal from the timing sensor means by a variable threshold value; position sensing means for sensing a passing position of the light beam in a direction orthogonal to a scanning direction of the light beam to scan the scanning surface by the scanner means based on an output of the digitizing means; passing position control means for controlling a passing position of the light beam on the scanning surface to be scanned by the scanner means based on a sensing result of the position sensing means so that the passing position of the light beam becomes a proper position; power sensor means for sensing a power of the light beam, which scan the scanning surface, based on the output of the digitizing means; power control means for controlling the generating means based on a sensing result of the power sensor means so that the power of the light beam becomes a fixed value; and threshold value control means for changing and controlling the threshold value of the digitizing means according to a light beam power control volume by the power control means.