Nippon Steel Corporation

Youichi Nagatake

Kazuo Yamamoto

Koichi Kitamura

Kouichi Matsumoto

Hidenori Mimura

Yasumitsu Ohta

Kazuyoshi Sai

A contact type image sensor including a plurality of photodiodes for converting a light signal into an electric signal according to the intensity of the light and a plurality of blocking diodes, arranged in either a back-to-back or a front-to-front connection with the photodiodes, for functioning as switching elements to have the information stored on the photodiodes read out, and adapted to be driven by a matrix drive system. For a back-to-back connection of the blocking diodes and photodiodes, a control circuit maintains the potential difference between cathodes of the photodiodes at zero volts at all times. Similarly, for a front-to-front connection of the blocking diodes and photodiodes, a control/drive circuit maintains the potential difference between the anodes of the photodiodes at zero volts at all times. Since the potential difference between the cathodes (for the back-to-back connection) or anodes (for the front-to-front connection) of all of the photodiodes is always maintained at zero volts, crosstalk at crossover portions between output lines connected to the photodiodes is reduced.

Contact type image sensor

An image sensor apparatus includes a matrix array of optical/electrical conversion elements, switching elements for taking out electric charge stored on the conversion elements, and drive circuits for driving the switching elements thereby to take out image signals from the conversion elements in parallel. A matrix array of noise signal retaining circuits is provided on output sides of the conversion elements for temporarily retaining in parallel, as noise signals, signals produced while the optical/electrical conversion elements are not being driven. Subtracting circuits are provided for subtracting from the parallel image signals in parallel the noise signals retained in the noise signal retaining circuits. A multiplexer converts the parallel output signals from the subtracting circuits into a serial signal in a predetermined sequence. Thus, the image sensor apparatus temporarily retains in parallel the parallel noise signals produced as a result of fluctuations in the characteristics of circuit elements, and cancels out with the subtracting circuits substantially the same noise which is contained in the image signals output from the conversion elements.

Image sensor apparatus with noise cancellation circuitry

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Tokyo, Japan

Youichi Nagatake