Patent ID: 6163333
Filing Date: 2000-12-19
Classification: B41J,G06K,H04N

Abstract:
A multi-beam scanning optical apparatus comprising first and second light sources for emitting beams, first and second drive circuits for driving said light sources independently to emit beams, first and second collimator lenses disposed corresponding to each beam emitted from said first and second light sources for transforming said each beam into parallel light, first and second cylindrical lenses disposed corresponding to each beam emitted from said collimator lenses for focusing said each beam in a subscanning direction, optical path correcting means for moving the second cylindrical lens in the sub-scanning direction for correcting an optical path of the second beam, a beam splitter for nearly matching optical axes of the first and second beams emitted from said cylindrical lenses, a deflector having one or more deflecting surfaces near a focusing point of the cylindrical lenses for deflecting the beams, a scanning lens system for focusing the first and second beams deflected by said deflector on a scanning surface, a synchronism detector for detecting the timing of each beam for synchronizing said first and second beams and respective print signals in a main scanning direction, a sensor unit disposed on an optical path of first or second beam emitted from said beam splitter in a different direction from said deflecting surface for detecting an output level of the beam, a knife edge shaped plate disposed between said beam splitter and said sensor unit and disposed at a position optically equivalent to said deflecting surface, and an optical path correcting means control circuit for calculating a set target value of the sensor output of the second beam calculated from the sensor output level of said first beam and each sensor output characteristic data of the first and second beam measured preliminarily, and controlling said optical path correcting means by said calculated value.