| 摘要 |
PURPOSE:To strengthen noise-proof and to make a design easier by reading out directly an incidence signal light to a photoelectric conversion element as the signal of pulse number corresponding with a light quantity. CONSTITUTION:At time t0, the potential of the terminal voltage Vc of a capacitor C9 is zero potential because a reset pulse PR is inputted to a reset switch SW10 and makes it on. After the time t0, by the disappearance of the pulse PR, the SW10 is made off and the C9 starts the storing of charge arising at a photodiode PD1 and a voltage Vc rises gradually. The more incidence light quantity of the PD1, the faster the speed of the rise of the Vc and when Vc>=V0, the one side input of an AND gate circuit 12 is turned on and this state is kept until the next pulse PR is inputted. And when a read out pulse Pr is inputted, a pulse signal is outputted and it continues until the C9 is reset. Therefore, the more incidence light beam is inputted to the PD1, the earlier the transmitting time of the signal is started and the number of an output pulse that corresponds to a light quantity is obtained.
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