Technique to increase dynamic range of a ccd image sensor

Abstract

A method of driving a solid-state imaging device to increase the dynamic range of a CCD image sensor is described. The imaging device has a plurality of light receiving members arranged in a matrix in horizontal and vertical directions. In addition, a plurality of columns of vertical CCD registers associate with the light-receiving members for storing signal charges received from a plurality of light receiving members. A row of horizontal CCD registers is disposed and connected with one end of each columns of vertical CCD registers to transfer the signal charges received from those vertical CCD registers to an output circuit member. The method comprises receiving the signal charges from an object by those light-receiving members for a time period Cs firstly in a normal fashion in BLANKING “high” period. Then the extra exposure time Cx is performed by utilizing the BLANKING “low” period as follows: sending a reading pulse to read out the signal charges from all light receiving members simultaneously and independently to the adjacent vertical CCD registers at a beginning of a blanking period. After that, the light receiving members are vacant. The signal charges from the object by light receiving member are read and the signal charges are read into vertical CCD steps, repeated, several times to increase the dynamic range. The Cx should be smaller than (n−l)×Cs for avoiding the charge blooming, where n is the value of a capacity of VCCD divided by a capacity of photo sensor.