JPS6439178A - Image pickup device ensuring high sensitivity - Google Patents

Abstract

PURPOSE:To improve the limit of an SN ratio against incident light quantity to an image sensor and to realize the high sensitivity with an image pickup device, by reading out the repetitive signals to integrate them while holding an electric charge image corresponding to an optical image on the photoelectric conversion surface of the image sensor. CONSTITUTION:When a shutter 3 is opened by a shutter driver 5, an optical image is instantaneously made incident on the photoelectric conversion surface of an image sensor 4. Thus an electric charge image is formed and then read out in synchronism with a closing action of the shutter 3. The optical signals equivalent to a single frame obtained by a first reading scan are stored in a frame memory of an integrator 6. The optical signal obtained from a second reading scan of the same electric charge image is added to the first optical signal read out of the frame memory via an adder. These added signals are stored again in the frame memory. Hereafter these actions are repeated and the integrating action is continued. When said repeating frequency reaches a prescribed level, said actions are stopped and the integrated optical signals of the electric charge image equivalent to one frame are outputted from the integrator 6 as analog signals.