Bar code reading system

Abstract

Abstract PURPOSE:To improve the reading accuracy of bar codes by measuring each width of bar codes equivalent to a single character through a counter and then specifying the threshold value based on both the maximum and minimum count values. CONSTITUTION:The contents of a counter are read out at a point where a bar changes to white from block and vice verse under the control of a control part 7. The readout contents are stored in a prescribed memory. If it is supposed that the contents of the counter equivalent to a single character (N pieces) are all stored is addresses A1-AN of a memory 6. Then the black and white maximum count values are set to both registers P and R respectively. While the black and white minimum count values are set to registers Q and S respectively. Then both black and white threshold values are calculated from X=P+Q/2 and Y=R+S/2. Based on these threshold values, the levels of counter data A1-AN on bar codes are compared with each other. If these data levels are smaller or than or equal to said threshold values, the logical value O is set. While the logical value 1 is set if the data levels are larger than the threshold values. These logical values are stored in B1-BN of a memory 7. Then these B1-BN are compared with a character conversion table 8 and converted into the corresponding characters when the processing is finished for all N pieces of characters.

Inventors

• 👤 Katsuzo Sakai
• 👤 酒井　勝三

Bibliographic Details