Demonstration of a frequency-demodulation CMOS image sensor

Koji Yamamoto; Keiichiro Kagawa; Jun Ohta; Masahiro Nunoshita; Yasushi Yamasaki; Kunihiro Watanabe

doi:10.1117/12.476788

16 May 2003 Demonstration of a frequency-demodulation CMOS image sensor

Koji Yamamoto, Keiichiro Kagawa, Jun Ohta, Masahiro Nunoshita, Yasushi Yamasaki, Kunihiro Watanabe

Proceedings Volume 5017, Sensors and Camera Systems for Scientific, Industrial, and Digital Photography Applications IV; (2003) https://doi.org/10.1117/12.476788
Event: Electronic Imaging 2003, 2003, Santa Clara, CA, United States

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.

Citation Download Citation

Koji Yamamoto, Keiichiro Kagawa, Jun Ohta, Masahiro Nunoshita, Yasushi Yamasaki, and Kunihiro Watanabe "Demonstration of a frequency-demodulation CMOS image sensor", Proc. SPIE 5017, Sensors and Camera Systems for Scientific, Industrial, and Digital Photography Applications IV, (16 May 2003); https://doi.org/10.1117/12.476788

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