Abstract: A contact image sensing system that eliminates the use of npn phototransistors. The device comprises a plurality of sensing elements, a like number of dummy sensing elements, control and drive clocks, a digital scanning shift register, and a differential amplifier. The device operates by sequentially reading the voltage output of the sensors, then comparing that output with the output of the dummy sensors so that any noise or offset in the signal can be cancelled by a differential amplifier.

Abstract: A color-reproducing contact image sensing (CORCIS) system that eliminates the use of multiple arrays of photodetectors with separate color filters and which permits the use of any of various signal-processing improvements such as voltage pickoff, transducer gain and correlated double sample and hold processing. The device operates by sequentially illuminating the colored object to be reproduced by primary color illumination means, with each illumination transferring in parallel the appropriate color response to a readout register for sequential readout. The sample and hold, and the parallel transfer operation, allow the CORCIS system to be able to read out signal while the detector array is integrating the next color signal, thus improving the sensitivity.