1. a-Si TFT Driven Direct-Contact-Type Image Sensor.
- Author
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Nagata, Tatsuya, Shimizu, Hiroya, Watanabe, Michihiro, Hashimoto, Satoru, and Kurihara, Keisuke
- Subjects
PHOTOELECTRICITY ,THIN films ,SOLID state electronics ,SOLIDS ,SURFACES (Technology) ,PHOTOCONDUCTIVITY - Abstract
A direct-contact image sensor with an a-Si thin-film transistor (TFT) shift register and a sensor element for correcting shading due to a variation of a light source has been successfully fabricated and its properties have been evaluated. The V
t -shift of TFTs in the shift register was reduced by applying negative gate voltage during the rest period of the sensor. Because of this procedure, the sensor lifetime was prolonged. A bit rate of 500 kHz was obtained under the driving condition of 32 bits/block matrix driving and 15.6 kHz operation of the shift register. The sensor element is composed of a photoconductor for detecting the light from the light source and one for detecting the light reflecting from a document, which are serially connected. By matching photoconductivity exponents γ of the two photoconductors, the shading was corrected efficiently. [ABSTRACT FROM AUTHOR]- Published
- 1993