IMAGE SENSOR WITH FUNCTION OF PREVENTING SATURATION IN PIXEL

摘要

PROBLEM TO BE SOLVED: To provide an image sensor capable of preventing saturation in pixels, which prevents saturation without reducing color reproducibility of the whole screen by varying a dynamic range in pixels depending on a light volume. SOLUTION: The image sensor includes: a drive transistor Q4 which amplifies at a fixed gain the amount of optical charge generated by a photodiode PD; saturation detecting means 31 and 32 which determine that the image sensor is in a saturated state when an output voltage Vx of the transistor Q4 exceeds a critical level; a switching means Q3 which is turned on or off according to the results of the determination by the saturation detecting means; and floating diffusion FD1 and FD2 which are coupled simultaneously to the gates of the photodiode PD and the drive transistor Q4 selectively according to the on/off of the switching means, and accumulates the charge of the photodiode PD transmitted through the switching means. COPYRIGHT: (C)2007,JPO&INPIT