| 摘要 |
<p>A method and apparatus for reading label bar codes in which a photoelectric signal representative of an optically scanned bar code label is differentiated. The positive and negative peaks of the differentiated signal are detected, and the time intervals between the peaks are measured by counter means to produce output signals representative of the bar code label. A multi-level threshold comparison technique is used to detect and predict the occurrence of positive and negative peaks.</p> |
