| 摘要 |
PURPOSE:To obtain an excellent picture even when a semiconductor laser which varies in an oscillation wavelength is used by arranging a filter made of the same material with a photosensitive body on the optical path between the semiconductor laser and a photosensitive body. CONSTITUTION:The output laser beam of an APC circuit 15 is driven corresponding to an information signal to be recorded from an information signal source 16 to oscillate a laser beam L which is modulated by flashing, and the beam is collimated by a collimator lens 5 and made incident to the filter 9. The beam L passed through the filter 9 is deflected and swept by a rotary polygon mirror 6 to image form a spot on the photosensitive drum 8 through an image forming lens 7, making an axial scan on the drum 8. The laser beam is transmitted through the filter while being absorbed much by the filter where the photosensitive body has high sensitivity to obtain small illuminance on the photosensitive body. On the other hand, almost all the laser light is transmitted without being absorbed much by the filter where the photosensitive body has low sensitivity to obtain large illuminance on the photosensitive body. Consequently, the potential contrast between a light and a dark part is stabilized. |
