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Proceedings Paper

Improving the sensitivity of a vision chip using the software A-D conversion method
Author(s): Daisuke Takeuchi; Shingo Kagami; Takashi Komuro; Masatoshi Ishikawa
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Paper Abstract

We developed a new method of pixel-level Analog-to-Digital (A-D) conversion for vision chips, removing Fixed Pattern Noise (FPN) at the same time. Vision chips are CMOS image sensors integrating a processing element (PE) and a photodetector (PD) in each pixel. The chip can handle high frame rate images in real time because its processing speed is high due to the parallel processing and also because it does not need high-bandwidth communication. Pixel-level A-D conversion is an essential technology for vision chips because digital operations must be performed in each pixel. The vision chip, which we have developed, contains a programmable PE in each pixel, and it directly controls the behavior of the PD with the use of the software. In our developed method, the chip controls the reference voltage to cancel the FPN by using this feature. We applied this method to our vision chip, and confirmed that the FPN was reduced and the sensitivity improved. We made a test chip including only PDs to solve the problem on the existing vision chip. As a result of applying this method to the test chip, the detectable minimum illuminance improved about 40 times in comparison with applying our existing method.

Paper Details

Date Published: 7 June 2004
PDF: 11 pages
Proc. SPIE 5301, Sensors and Camera Systems for Scientific, Industrial, and Digital Photography Applications V, (7 June 2004); doi: 10.1117/12.526319
Show Author Affiliations
Daisuke Takeuchi, Univ. of Tokyo (Japan)
Shingo Kagami, Univ. of Tokyo (Japan)
Takashi Komuro, Univ. of Tokyo (Japan)
Masatoshi Ishikawa, Univ. of Tokyo (Japan)

Published in SPIE Proceedings Vol. 5301:
Sensors and Camera Systems for Scientific, Industrial, and Digital Photography Applications V
Nitin Sampat; Morley M. Blouke; Ricardo J. Motta, Editor(s)

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