國立臺灣師範大學電機工程學系W.-Y. WangM.-C. LuH.-L. KaoC.-Y. Chu2014-10-302014-10-302007-01-011549-7747�http://rportal.lib.ntnu.edu.tw/handle/20.500.12235/31946In this brief, a nighttime vehicle distance measuring system using charge-coupled device (CCD) cameras is proposed. The authors use the proportionality of similar triangles to measure the distance between a CCD camera and taillights of a vehicle in front. At night, the taillights form two bright spots in the CCD image, therefore producing two measurable signals. A circuit for counting the number of external clock pulses between the two bright spots is employed to calculate the interval between them in the video image. Due to the proportionality of similar triangles, there is a linear relationship between the actual distance and the interval of the two taillights. Thus, the actual distance from the CCD camera to the vehicle can be calculated from a simple formula. One does not have to use an expensive high-speed digital signal processing microprocessor to identify the taillights of the vehicle or use pixels to measure distance, but just use simple circuits to identify the taillights at night and use a simple formula to measure distance. Experimental results demonstrate the effectiveness of the proposed system.Distance measuring systemsproportionality of similar trianglesvoltage comparator