| 摘要 |
PROBLEM TO BE SOLVED: To enhance the stability of the signal waveforms of photodetection signals at photodiodes for receiving the beam light to be scanned and to stabilize the formation timing of a synchronizing signal for synchronizing scanning. SOLUTION: The PD(photodiode) 5 for outputting the photodetection signal by receiving the beam light to be scanned is composed of plural pieces of PD elements PD-1 to PD-N arrayed in the scanning direction of the beam light. A synchronizing signal forming circuit 6 for forming an SOS signal (synchronizing signal) in accordance with the photodetection signal from the PD 5 forms the SOS1 signal by the resonance amplification signal formed by resonance amplifying the photodetection signals of the plural PD elements in a time signal detecting section 11, forms a DLY signal from the photodetection signals of the light receiving elements in a timing detecting section 12 and forms the SOS signal by using the SOS1 signal and the DLY signal in a logic circuit section 13. The formation of the SOS signal is made possible by using the resonance amplification signal having a sufficiently high amplification level and the level fluctuation of the photodetection signals and the influence of the noise in the circuits are suppressed. The stabilization of the timing of the SOS signal is made possible.
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