SOLID STATE IMAGE PICKUP DEVICE

PROBLEM TO BE SOLVED: To obtain an output signal without losing color balance even if incident light changes from high luminance to low luminance during an exposure period.SOLUTION: A TX signal has a voltage value V3 at which Q1 is placed in a fully conductive state at the starting point of the exposure period. The TX signal decreases afterward in one direction of turning off the Q1 toward at the end point of the exposure period. At the starting point of the exposure period, light having quantities X1, X2 is incident, but the voltage value of the TX signal is V3, or high, so that a PD can be stored with only a small amount of electric charge. When the quantity of the incident light becomes 0, the amount of electric charge stored in the PD does not decrease below a sub-threshold level of the Q1, so it approximates a certain electric charge amount (y). In this case, the voltage value of the TX signal is set substantially to the voltage value V3 and the PD is stored with only a small amount of electric charge while the light having quantities X1, X2 is incident. Consequently, the electric charge amount (y) is much smaller than an electric charge amount (y) of a conventional pixel circuit.