Mutsuo Takenouchi

An Amorphous Si High Speed Linear Image Sensor

An amorphous silicon thin film linear image sensor of a sandwich structure has been developed. The sensor consists of a transparent ITO as an upper electrode, an a-Si: H layer and Cr or Al lower electrodes. The a-Si: H layer is formed by RF glow discharge. These layers are deposited on a glass or ceramic substrate. The sensor has good photoelectric characteristics as follows: Photo-sensitivity is 10-7 A/cm2 1x, photo-response time is less than 0.5 ms and photo- to dark-current ratio is larger than 3×103. The sensor can be operated by a -5 V single power source and this same power source can be used for the driving circuits. A 1056-bit, 8 bit/mm linear image sensor has been fabricated. Using the device, images of a document have been read and reproduced successfully.

Recent Development In Amorphous Silicon Image Sensor

Contact type linear image sensor arouse a great interest as a compact image reading component for a facsimile, an image scanner and many other applications. Among those, amorphous silicon linear image sensors which consist of Cr/a-Si:H/ITO structure have excellent features such as capability of fabrication of large area devices and material stability. B4 size, 200spi image sensors are now on mass production. B4 size, 400spi image sensors have been developed. And very large image sensors with 36 inch length and color sensors also have been developed. a-Si:H TFT driven image sensors which can reduce the cost are under development.