[OPTICAL REVIEW Vol. 7, No. 1 (2000) 66-72]
A High-Speed 12-Layer Two-Dimensional Bar-Code Detection System
Department of Electronics and Information Engineering, Tokyo Metropolitan College of Technology, 1-10-40, Higashi-Ooi, Shinagawa, Tokyo, 140-0011 Japan
(Received September 17, 1999; Accepted October 14, 1999)
A new photodetection amplifier configuration with an amplification-type current-to-voltage converter is presented to realize a high-gain wideband amplifier. A high-speed 12-layer two-dimensional (2D) bar-code detection system (BCDS), consisting of the new photodetection amplifier and a raster scanner combined with a complementary light emission drive method for laser diodes, has been developed to provide both a highly effective scanning speed and multi-layer bar-code detection. The 12-layer 2D BCDS has shown 1,250 scan/s, which is two and a half times the scanning speed of a conventional bar-code detection system. Comparison with experimental results verified that Li's scan pattern theory provides an accurate model for laser scanning beam traces obtained by the raster scanner. As theoretical evaluation of bar-code configuration in the new system, an optimum bar-code height per one-layer is given by a function of detection length.
Key words : bar code, light emission method, diode lasers, photodetection amplifier, scanner, model for scanning beam traces