Color Range Images Captured by a Four-Phase CMOS Image Sensor

As 3-D displays become more common, the demand for 3-D-related products is rapidly increased. Three-dimensional image sensors based on the time-of-flight (TOF) technique are one of these products and are applied to many applications. In this paper, a new pixel based on the continuous-wave modulation method was proposed to measure the TOF and was embedded in a test complementary metal-oxide-semiconductor (CMOS) image sensor. Compared with other range imagers, no complex control signals, high operating voltage, or multilevel control voltages are needed in this pixel. The chip, with 92 × 30 pixels, was fabricated using the Taiwan Semiconductor Manufacturing Company's 0.18-μm CMOS standard process, and a time-switched color measurement was applied to this rangeflnder system. A pulse train of red, green, and blue lights is emitted sequentially from a light-emitting diode array. The distance is easily calculated from the phase differences, and the color information is estimated using the difference in reflection coefficients under a different light. The measured distance and color are compared with the actual dis tance and color-corrected images. A color range image with a distance error of 3.56 cm and an L*a*b color difference of 40.23 can be observed. This rangefinder system provides a new perspective to capturing a colored range image.