| 摘要 |
PROBLEM TO BE SOLVED: To obtain a solid-state image pickup device that covers a desired luminous quantity range over a wide range without increasing the scale of a counter circuit. SOLUTION: A FET switch S2 is closed when '1' is set to a 7th bit, a discharge resistance (ON resistance) of charges stored in a photo diode 12A is decreased and a discharge time constant is decreased, then deeper resetting is attained. Similarly in the case of an 8th bit, when '1' is outputted, the ON resistance at resetting is further decreased and the discharge time constant is furthermore decreased. Thus, in the case of counting number of photons under the same luminous quantity, number of pulses counted per unit time is decreased, resulting in decreasing the sensitivity and widening the dynamic range.
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