| 摘要 |
In the circuitry for bar code scanners, a cascade of amplifiers is used to amplify the bar code signal from the photodetector (30). An amplifier (32) having a logarithmic signal compression characteristic is included in the cascade, preferably after an amplifier which serves to differentiate the signal. The amplified signal is applied to a digitizer (34) including a comparator which is sensitive only to the leading edge.
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