Hiroo WAKAUMI^*

Division of Electronics and Information Engineering, Tokyo Metropolitan College of Industrial Technology, Shinagawa, Tokyo 140-0011, Japan

(Received January 17, 2011; Accepted July 1, 2011)

A fixed-period delay method is proposed to increase the detection range and detection stability of a ternary barcode detection system. The system combines an envelope differential detection technique containing nonlinear filtering and a fixed-period delay to detect the barcode over a longer range and at higher scanning speeds while being simple and capable of handling a large amount of information. The system was demonstrated with its miniaturized circuit, and it was established that the detection range of the system for a minimum bar width W = 0.25 mm was 1.8 times that of the conventional count-latch envelope differential technique because of the stable delay achieved by a shift register and the noise suppression by a nonlinear filter. In addition, the system operated at a maximum scanning speed of 8.3 times that of conventional charge-coupled device cameras under the practical detection range for W = 0.3 mm. This system is expected to facilitate the real-time identification of goods on production lines and in automated warehouses.

Key words: optical detection system, laser diode, barcode, ternary, signal processing

^*E-mail address: wakaumi@s.metro-cit.ac.jp