SIGNAL PROCESSING CIRCUIT FOR CLOSE CONTACT IMAGE SENSOR

摘要

PURPOSE:To obtain a picture with high quality by using a sample-and-hold circuit and a subtractor circuit so as to eliminate noise caused for each output channel due to the dispersion in the characteristic of circuit components of plural output channels for each output channel. CONSTITUTION:A picture signal obtained by fetching a picture is integrated by integration circuits 181-18n and the result is fed to one terminal of subtractor circuits 221-22n and a value held in noise cancel sample-and-hold circuits 201-20n is fed to the other terminal. The subtractor circuits 221-22n subtract the value held in the sample-and-hold circuits 201-20n from the picture signal. Since a noise component of each output channel fed to the picture signal and a noise stored in the sample-and-hold circuits 201-20n of a relevant output channel are almost equal to each other, then the noise specific to each output channel is subtracted from the picture signal of each output channel and the noise component is eliminated from the picture signal of all the output channels. Thus, the picture with high quality is obtained.