| 摘要 |
PURPOSE:To extend the dynamic range of a solid state image pickup element, by delivering a dark current signal and a scan signal including the current signal from the solid state image pickup element and then controlling the integral time of the signal obtained by subtracting the dark current signal from the scan signal. CONSTITUTION:With application of a power supply, an up-down counter UDC is reset by the reset pulse PUC given from a timing control circuit TCC. At the same time, transfer clock pulses phi1 and phi2 are applied to a solid state pickup element SP from the circuit TCC. The circuit TCC starts the counting of the accumulated time indicated by the counter UDC. While the signals givn from dummy picture element parts D1 and D2 are sent to an operational amplifier OP1 forming a differential amplifier to obtain the difference to the element SP as the dark current signal of the SP. The counter UDC is counted down by the dark current signal, and the designated accumulated time is switched. As a result, th dynamic range of the element SP can be increased even to the increase of the dark current level which is caused by an increment of the incident light volume. |
