Spatial Optical Communication Image Sensor with CMOS Image Sensor

Since LEDs are widely used for the traffic lights or tail lights, the spatial optical communication using LEDs is expected for applications to car-to-car and road-to-car communication. We have been investigating CMOS image sensors for the spatial optical communication. The sensor has functions of the image acquisition and the searching for the communication source. To realize there functions this image sensor has an array of pixels for imaging and communication alternatively arranged. The pixel structure for the communication signal has a structure as shown in the figure below. Parasitic capacitance of the photo diode is reduced by the fringing electric field, and the generated charge instantly moves to the charge detection part. Using this technology, a long distance (>100m) and high career frequency (>10Mbps) in the spatial optical communication has been achieved. This CMOS sensor chip has been presented at ISSCC 2010.

Spatial optical communication image sensor	Pixel structure for communication signal
Block diagram chart of image sensor	Taking picture image (a&b), Signal reproduction image (c&d)

Refernces

1. S. Itoh, I. Takai, M. Z. Sarker, M. Hamai, K. Yasutomi, M. Andoh, S. Kawahito," A CMOS Image Sensor for 10Mb/s 70m-Range LED-Based Spatial Optical Communication," IEEE Int. Solid-State Circuits Conf., Dig. Tech. Papers, pp402-403.
2. S. Itoh et al.," A CMOS Image Sensor for Car-to-Car/Raod-to-Car Optical Communication Systems and evaluation of the Optical Communication Pixel," ITE , Tech. Papers, vol.33, no.18, IST2009-16, pp33-36
3. M. Z. Sarker et al.," A CMOS Imager and 2-D Light Pulse Receiver Array for Spatial Optical Communication," IEEE Asian. Solid-State Circuits Conf., Dig. Tech. Papers, pp113-116.