| 摘要 |
PURPOSE:To conduct a correct main scan without generating deflection in the direction of subscan, by detecting a tripping angle of the bearing shaft center of a scanner motor fitted with a polygon mirror on the outer peripheral face of a rotating member and by correcting said tripping angle. CONSTITUTION:A housing 10 is formed airtightly by an upper side member 11 having a cover 13 and by a lower side member 12 equipped with a base stand 14. A fixed part is formed by a fixing member 20 pressed into said base stand 14 and a rotating member 30 is caused to engage around said fixed part via minute radial gaps. Said rotating member 30 is caused to rotate by a magnet 40 at the outer periphery of the rotating member 30 and by an electromagnetic coil 42 on the inner peripheral face of the upper side member 11. A polygon mirror 35 provided on the lower side of the flange 34 of said rotating member 30 is held between a driven plate 54 and the flange 34. The displacement of said polygon mirror 35 is detected by a displacement gauge 50 provided in non-contact manner and in the vicinity of the polygon mirror 35 and its output is inputted to at least a pair of driving elements 52 facing said driven plate 54 to correct tripping of the bearing shaft center of the rotating member 30. Thus, a main scan by the reflected light of the polygon mirror 35 is conducted correctly. |
