| 摘要 |
PURPOSE:To form an optical scanner which is capable of changing easily a scanning density by providing plural rotary polyhedral mirrors of different kinds on the same shaft. CONSTITUTION:A motor 4, etc. continue a rotation at a constant speed, and a rotary polyhedral mirror 8c is selected. A motor 17 which has received this selected instruction rotates, and transmits this rotational power to a shaft 13 through a gear 16 and a gear 15. When this shaft 13 rotates, being supported by bearings 11, 12, a moving member 14 which is screwed into this screw part and does not rotate, and a moving pedestal 19 are guided by a guide rod 18, and descend together with the motor 4 and a rotary polyhedral mirror body 8. Just in this case, when the rotary polyhedral mirror 8c comes to the original position where a rotary polyhedral mirror 8a does not move yet, a light from a light emitting source 22 is photodetected by a photodetector, a position detecting signal is generated, the motor 17 stops a rotation by this signal, and the rotary polyhedral mirror body 8 is positioned. Subsequently, a laser beam oscillated by a semiconductor laser 1 by a scanning instruction is made incident to the rotary polyhedral mirror 8c, after the beam diameter is expanded in a state that it remains a parallel light, by a collimator lens 2. |
