[OPTICAL REVIEW Vol. 18, No. 5 (2011) 408-413]
© 2011 The Japan Society of Applied Physics
A High-Density Ternary Barcode Detection System Employing a Stable Fixed-Period Delay Method
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
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