| 摘要 |
A bar code reading apparatus includes a light source for illuminating a bar code, a light receiving part for receiving reflected light from the bar code and for subjecting the received reflected light to a photoelectric conversion to output an electrical signal, and a decoding part for decoding the bar code by reading width data related to widths of the bars and spaces of the bar code based on the electrical signal from the light receiving part. The decoding part includes a sampling part for sampling the electrical signal from the light receiving part with a predetermined period and for outputting sampled data, a calculating part for calculating an average value of the sampled data for every predetermined interval, where the predetermined interval is greater than a maximum width of a noise which is detectable from the electrical signal, and an operation part for obtaining intersecting points where a waveform connecting the sampled data and a waveform connecting the average values intersect and for reading a width of each bar and space within the bar code based on an interval between each two adjacent intersecting points.
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