| 摘要 |
A MEMS-based reader has an extended range of working distances for reading bar code symbols A digitizer resolves the edges of bar code symbols when located at far-away distances from the reader within the working range The digitizer includes a differentiator for differentiating the analog signal to generate a first derivative signal, a peak detector for detecting voltage peaks m the first derivative signal, and a comparator for comparing voltage drops after the voltage peaks with a predetermined -voltage value, and for determining the presence of each edge when each voltage drop at least equals, and preferably exceeds, the predetermined voltage value. |
