| 摘要 |
<p>PURPOSE:To improve reliability on the change of laser beam form by impressing a voltage on a liquid crystal panel disposed between a collimator lens and a polygon mirror, and changing a transmitting area of the liquid crystal panel according to recording density. CONSTITUTION:A semiconductor laser 101 outputs the laser beam modulated according to every picture element data, and the laser beam is shaped to a collimated luminous flux by the collimator lens 102. Liquid crystal has such a characteristic that it is quasi-crystallized when the voltage is impressed and it intercepts the light, so that the liquid crystal shutter(liquid crystal panel) 103 executes the change of the laser beam by using the characteristics. Tat is, the laser beam passing through the collimator lens 102 is changed to the luminous flux having the form in accordance with the recording density by the liquid crystal shutter 103. The laser beam having the changed form of the luminous flux is allowed to scan by the polygon mirror 104 in the main scanning direction, and corrected by an ftheta lens 105, and irradiates a photosensitive body 106. Thus, the center of the beam does not deviate from the center of an optical path by using the liquid crystal shutter as an aperture.</p> |
