Barcode reader with edge detection enhancement

摘要

An optical reader for decoding an encoded symbol character of a symbology includes a scan data signal processor having as an input a scan data signal encoding information representative of the encoded symbol character. The scan data signal processor includes a first time delay stage adapted to provide a primary phase waveform from the scan data signal, a second time delay stage adapted to provide an early phase waveform from the scan data signal, and a third time delay stage adapted to provide a delayed phase waveform from the scan data signal. The early phase waveform has a propagation delay less than the primary phase waveform, and the delayed phase waveform has a propagation delay greater than the primary phase waveform. The scan data signal processor further includes a peak window detection stage for generating a peak window timeframe when an amplitude of the primary phase waveform is greater than, less than, or equal to both an amplitude of the early phase waveform and the delayed phase waveform. The optical reader further includes a digitizer circuit adapted to accept, within the peak window timeframe, the scan data signal processor output.

主权项

1. An optical reader for decoding an encoded symbol character of a symbology, the optical reader comprising:
a laser source for generating a laser beam along an optical path; a lens assembly for focusing the laser beam on the encoded symbol character at a plane of focus; a scanning mechanism for oscillating the laser beam at a pre-determined frequency to sweep over the encoded symbol character according to a pre-described scan pattern; a photodetector having as an input detected light intensity corresponding to the laser beam scattered off the scanned encoded symbol character, and having as an output a scan data signal encoding information representative of the encoded symbol character; and a scan data signal processor having an input and an output, the scan data signal processor comprising a first time delay stage adapted to provide a primary phase waveform from the scan data signal, a second time delay stage adapted to provide an early phase waveform from the scan data signal, the early phase waveform having a propagation delay less than the primary phase waveform, and a third time delay stage adapted to provide a delayed phase waveform from the scan data signal, the delayed phase waveform having a propagation delay greater than the primary phase waveform, the scan data signal processor further comprising a peak window detection stage for generating a positive peak window timeframe, the positive peak window timeframe only opening when an amplitude of the primary phase waveform is greater than or equal to both an amplitude of the early phase waveform and the delayed phase waveform and the positive peak window timeframe closing only when either (i) the amplitude of the primary phase waveform is less than an amplitude of the early phase waveform or (ii) the amplitude of the primary phase waveform is less than an amplitude of the delayed phase waveform; and a digitizer circuit adapted to accept, after the positive peak window timeframe, the scan data signal processor output.