| 摘要 |
PURPOSE:To detect surely the position shift in orthogonal direction to the scanning direction, by providing a photoelectric converting means having a photo detecting means where the width in the laser beam scanning direction is changed sequentially in response to the position orthogonal to the scanning direction, in a deflecting scanning optical path of a laser beam. CONSTITUTION:The photoelectric converting element 5 has photo detecting plane (Fig. a) having a start end prolonged in a direction orthogonal to the scanning direction of a beam spot and an end tilted to this start end, and the output signals Vsa-Vse are applied to an operational amplifier 6. Taking the center of the beam spot as a center 15c, and when adjusting the range between 15b and 15d, a range set power supply (-Ve1) of the operational amplifier 9 is made equal to an integration output signal obtained at the repetition of the spot 15b so as to set a range set power supply (-Ve2) of an operational amplifier 10 to the integrating output signal obtained with the repetitive scanning of the spot 15d. Thus, when the position of the beam spot 15 is within the said range, light emitting diodes 11, 12 are put out at all times. |
