| 摘要 |
An electric signal current corresponding to the intensity of the incident light is output by a photodiode PD, electric charge is integrated in an integrating circuit 10 according to this electric signal current, and a signal voltage corresponding to this quantity of electric charge thus integrated is output. In a CDS circuit 20, the signal voltage output by the integrating circuit 10 is input to the capacitor C21, and an electric charge corresponding to the amount of change in the input signal voltage is integrated in the capacitor C22 or C23 selected by switches SW21-SW23. In the differential calculating circuit 30, the differential in the electric charges integrated respectively by the capacitors C22 and C23 or the CDS circuit 20 is determined, and a signal voltage corresponding to this differential is output.
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