| 摘要 |
A scan velocity detector for detecting scan velocity when a surface of an object is scanned with a beam of light generated by a lightprojecting means; the scan velocity detector comprising light-receiving means to receive light which is reflected, threshold-level setting means for setting threshold levels, delay means for delaying the output of the light-receiving means and counting means for counting the time from when the output of the delay means exceeds a certain threshold level until it reaches a different threshold level, the scan velocity detector being an integral part of a bar code scanner, or similar device.
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