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Method and apparatus for reducing bandwidth limited noise in bar code scanner

  • US 5,852,286 A
  • Filed: 03/20/1996
  • Issued: 12/22/1998
  • Est. Priority Date: 03/20/1996
  • Status: Expired due to Fees
First Claim
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1. A bar code scanner system comprising:

  • a laser light source that periodically produces a light beam that is swept across a bar code label, the laser light source being periodically turned "on" and "off" according to a duty cycle;

    a detector that produces a first electric signal representative of received ambient light and light reflected from the bar code label when the light source is "on" and produces a second electric signal representative of received ambient light when the light source is "off";

    a demodulator circuit, coupled to the detector, that provides a first gain to the first electric signal and provides a second gain to the second electric signal;

    a filter, coupled to the demodulator circuit, that receives the electric signals from the demodulator circuit and reduces out-of-band signal components; and

    a laser pulser coupled to the laser light source and the demodulator circuit, that controls the duty cycle of the laser light source.

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