| 摘要 |
PROBLEM TO BE SOLVED: To obtain a photodetector which can output a light detect signal as a write timing for image signals and can output a signal showing an intensity of incident light by monitoring and outputting a peak value of the intensity of incident light held by a holding means which holds the peak value for a fixed time. SOLUTION: In a photodetector 10, an amplifier 103 multiplies a current outputted proportionally to an intensity of incident light from a photodiode 101 (current/voltage from a resistor 102) by four times, and an amplifier 104 amplifies the current by two times. An output of the amplifier 104 is held for a fixed time by a capacitor 105 via a diode 109. An output of the amplifier 103 and the value held by the capacitor 105 are compared at a comparator 106. An output of the comparator 106 is compared with a reference voltage by a hysteresis comparator 107. The comparison result is outputted by a binary value. A voltage held in the capacitor 105 is outputted via an amplifier 108.
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