A high-density ternary barcode detection system with a fixed period delay method

A ternary barcode detection system employing a fixed-period delay method is proposed to increase its detection range and detection stability. The system combines the envelope differential detection technique containing nonlinear filtering and fixed-period delay to detect over a longer range and also at higher scanning speed while being simple and capable of handling a great amount of information. The system was demonstrated with its miniaturized circuit and it was confirmed 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 CCD cameras under the practical detection range for W = 0.3 mm. This system is expected to enable the real-time identification of goods on production lines and in automated warehouses.