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Proceedings Paper

Demonstration of a frequency-demodulation CMOS image sensor
Author(s): Koji Yamamoto; Keiichiro Kagawa; Jun Ohta; Masahiro Nunoshita; Yasushi Yamasaki; Kunihiro Watanabe
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Paper Abstract

A frequency-demodulation CMOS image sensor for capturing images only by the modulated light is proposed and demonstrated. The pixel circuit has two FD (floating diffusion) for accumulating signal charges and one photo-gate for detecting the modulated light and the background light. By operating the image sensor synchronously with a frequency and a phase of the modulated light, signal charges generated by the modulated light and the background light are accumulated at FD of one side, while signal charges generated only by the background light are accumulated at another FD, respectively. By subtracting outputs of two FD with the off-chip subtraction circuits, images produced only by the modulated light can be obtained. Based on the proposed circuit, an image sensor with 64 × 64 pixels are fabricated by using 0.6 μm CMOS technology. We captured images by using this image sensor and demonstrate the sensor can capture images only by the modulated light. When the object is partially illuminated by the modulated illumination under constant background illumination, we can successfully demonstrate the image sensor captures the potion illuminated by the modulated light with removing any static background light. Also we demonstrate the marker detection. When the marker is attached to an object under several background illuminations, the image sensor can extract the marker without affected by the background illumination intensities. A motion capturing is successfully demonstrated by use of this sensor.

Paper Details

Date Published: 16 May 2003
PDF: 6 pages
Proc. SPIE 5017, Sensors and Camera Systems for Scientific, Industrial, and Digital Photography Applications IV, (16 May 2003); doi: 10.1117/12.476788
Show Author Affiliations
Koji Yamamoto, Nara Institute of Science and Technology (Japan)
Keiichiro Kagawa, Nara Institute of Science and Technology (Japan)
Jun Ohta, Nara Institute of Science and Technology (Japan)
Masahiro Nunoshita, Nara Institute of Science and Technology (Japan)
Yasushi Yamasaki, Microsignal Co., Ltd. (Japan)
Kunihiro Watanabe, Microsignal Co., Ltd. (Japan)


Published in SPIE Proceedings Vol. 5017:
Sensors and Camera Systems for Scientific, Industrial, and Digital Photography Applications IV
Nitin Sampat; Ricardo J. Motta; Morley M. Blouke; Nitin Sampat; Ricardo J. Motta, Editor(s)

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