| 摘要 |
PURPOSE:To always attain optimum storage time control by comparing a difference signal between a maximum value and a minimum value of storage signals with plural prescribed levels and deciding the amplification factor of the storage time and a readout signal according to the result. CONSTITUTION:Comparators 13, 14 compare a difference signal of a maximum value Vmax and a minimum value Vmin from a differential amplifier 12 respectively with a reference level Vref+Vref/4. A comparator 15 compares the maximum value Vmax with a prescribed level smaller than the saturation level Vref-L of a sensor (photoeletric conversion element). The amplification factor of an amplifier 17 whose amplification factor is variable depends on an inputted gain control signal Gcont. That is, when the gain control signal Gcont is at a high level, the amplification factor is controlled to be the unity and when the gain signal is at a low level, amplification factor is controlled to be 4. Thus, the optimum storage control is attained. |
