| 摘要 |
PURPOSE:To exclude saturation of the electric-charge inflow quantity into the CCD (charge coupled device) against any incidence of light and to maintain a prescribed value or above by changing the bias voltage to be applied to the input gate by a detecting signal. CONSTITUTION:After amplified by an amplifier 5, the signal from a solid-state image pick-up element 4 is digitized by an A/D converter 6. And, by a multiplexer 7, the output signals correspondent to the max., intermediate, and min. values of the voltage VIG to be applied to the input gate IG are allotted to respective frame memories 8, 9, and 10, and stored. The outputs from the frame memories are subtracted by subtracters 11 and 12. At comparators 13 and 14 in the next sequence, the difference between them is decided whether more or less than the prescribed value. The picture elements whose difference exceeds the prescribed value are counted by counters 15 and 16. An MPU17, decides the saturation or non-saturation of the input gate voltage from the output values of these counters, and depending on its result, sets the voltage value VIG for the next cycle.
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