| 摘要 |
PURPOSE:To obtain a stable and accurate waveform by driving and controlling only a light source corresponding to one scanning light among plural scanning light beams while the scanning light is guided to a beam photodetection part according to a horizontal synchronizing signal. CONSTITUTION:Two layer diodes 50 and 51 emit two laser beams 309 and 310 as scanning light beams and only one laser beam 209 between the two laser light beams 309 and 310 has its scanning end reflected by a reflecting mirror 307 (while the other is turned off). A beam light detector 308 generates the horizontal synchronizing signal with the reflected scanning light and this horizontal synchronizing signal is used to time the recording of video data, i.e. the light emission of the laser diode. Therefore, only one light beam is allowed to pass on the beam light detector 308. Consequently, the quantity of light to the beam light detector and the shape of the beam light are stable and the stable and accurate output waveform is obtained from the beam light detector.
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