A high-density ternary barcode detection system employing an envelope-differential composite method

A ternary barcode detection system employing an envelope differential composite method was developed to increase both detection resolution and range. This system, adaptable to any ternary barcode pattern through the subtraction of an attenuated and slightly enveloped line of the detected barcode signal from the original signal, enables longer range detection of high-density barcodes at higher scanning speeds and so allowing a large amount of information to be obtained. The prototype system, using a four-character ternary barcode with a minimum width of 0.3 mm consisting of nine elements per character, was confirmed to successfully detect over a range of more than 5 cm at a maximum scanning speed of 351 scan/sec, which is 7 times the scanning speed using conventional CCD cameras. This detection range is 4.5 times longer than that using the conventional dual threshold method. This system is expected to enable the real-time identification of goods on production lines and in automated warehouses and to be used extensively in other applications.