| 摘要 |
PROBLEM TO BE SOLVED: To obtain the accurate bar code information by calculating an inflection point of each waveform of analog signals which undergone the photoelectric conversion by a CCD and performing the binarization processing. SOLUTION: A bar code label is read by a CCD image sensor 1 and then is subjected to the photoelectric conversion, the elimination of noises via an LPF 2 and the amplification of signals via an amplifier 3 respectively. Then the bar code label is inputted to a differentiator 4. The output signals of the differentiator 4 are converted into a series of a series of positive pulse strings via an absolute value circuit 5 and inputted to a comparator 6. Thus, a binary digital signal waveform (B) is generated. Then the rise start and end points of a bottom area and the fall start and end points of a peak area are detected for every analog signal waveform, and an inflection point, i.e., the middle point between every start point and end point is calculated. This inflection point is regarded as a switching edge of signal polarity of the waveform (B) to perform the binarization processing. |
