| 摘要 |
PURPOSE:To make it possible to correct the output variation of the position detector and perform the proper focusing, by detecting the maximum value and the minimum value of a scanning mirror position signal, and applying the potential according to both the limiting values to both the ends of the potentiometer. CONSTITUTION:An output of the scanning mirror position detecotor is input to the minimum value detection circuit 33 and the maximum value detection circuit 38 through the buffer circuits 18, 19. Since the potentiometer 48 is connected between the buffer circuits 46, 47, the voltage of the maximum and minimum values of the mirror position signal is applied between these terminals. Also, the mirror position signal and the lens position signal of the potentiometer 48 are input to the servo- amplifier 26. According to this constitution, in case when an output of the photocoupler is varied by temperature, the voltage waveform of the mirror position signal is relatively leveled up by the potential EO, but since the potential of the potentiometer 48 also becomes high by that portion, the output variations of position signals of the mirror and the lens of the amplifier 26 are offset. In this way, proper focusing can be executed. |
