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Method and apparatus for reading bar coded data wherein the light source is periodically energized

  • US 4,160,156 A
  • Filed: 05/04/1978
  • Issued: 07/03/1979
  • Est. Priority Date: 05/04/1978
  • Status: Expired due to Term
First Claim
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1. Apparatus for optically reading bar coded data wherein the binary bits are encoded in terms of bars of different widths of the same optical characteristics separated by areas of the opposite optical characteristic comprisingoptical sensing means for producing electrical signals representative of the optical characteristics of a surface presented thereto upon the production of relative movement between the surface and the sensing means, said sensing means having a light source and a light sensor for receiving the light rays from the light source reflected from the surface being sensed, the sensor output signals including an unknown offset voltage,analog signal processing means for processing the signals from the sensor and providing analog signals representative of the sensed bars of the different optical characteristics,digital signal processing means for storing and continuously signalling the analog value of the offset signals generated and coupled to the analog signal processing means, andcontrol circuit means including means for automatically and periodically energizing the light source and the analog signal processing means and maintaining the energization of same in response to a signal representative of a bar of one optical characteristic and automatically de-energizing said same elements in response to a signal representative of a bar of the other optical characteristic.

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