Image sensor

Abstract

An self-scan type linear image sensor comprises an array of a plurality of phototransistors or photodiodes, a shift register, and current switches operating in response to parallel output signals from the shift register. The shift register is comprised of thyristors and interstage coupling transistors cascade-connecting the thyristors. The current switches are comprised of a first differential current switch executing differential switching operations between parallel output signals from odd-number stages of the shift register and a first separation signal, and a second differential current switch executing differential switching operations between parallel output signals from even-number stages of the shift register and a second separation signal. Current outputs from these current switches are delivered to collectors of the phototransistors, which are connected at emitters, common to an image signal output line.