PURPOSE: To enable accurate detection of the difference of 2 signals, by constructing 2 electric charge accumulators per each light receiver in a circulating loop and computing the difference of 2 signals with the electric charge accumular and an operational amplifying means.
CONSTITUTION: Photoelectic charges generated in light-sensitive image elements S1WSN are accumulated by an electric charge accumulators ST1. When SH1 and A reach high level, the electric charge accumulated in the accumulator ST1 is transmitted tentatively to an electric charge transmittor and when it is inverted the SH1 low level, then the electric charge is accumulated in an accumulator ST2. When electric charges accumulated in the accumulators ST1, ST2 are transmitted tentatively to electric charge transmittors GA, GB and SH1 is inverted to the low level, the information charge of the ambient light is accumulated in the accumulator ST2. The information charge at the light emission time is delivered to the accumulator ST1 and after addition, the same operation is repeated successively. Light information at the light emission time and the same at the light non-emission time are added in a circulating manner. Thus, the difference signal of 2 signals obtained from a photoelectric convertor at the time of light emitting and light non-emitting times can be detected at high accuracy.
SATOU YUUICHI
KAWABATA TAKASHI
