Frequency division multiplexed bar code scanner
First Claim
1. A frequency division multiplexed scanner system comprising:
- a plurality of radiation sources for simultaneously providing a plurality of source beams each having an intensity;
a modulator circuit for modulating the intensity of each source beam at a different frequency;
means for combining the source beams and directing them along a path to a bar code to be read;
means for receiving the source beams reflected from and amplitude modulated by the bar code; and
means, responsive to the source beams reflected from the bar code, for detecting the amplitude modulation of at least one of said source beams representative of the bar code read.
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Accused Products
Abstract
A frequency division multiplexed bar code scanner system includes a plurality of radiation sources for simultaneously providing a plurality of source beams, and a modulator circuit for modulating the intensity of each source beam at a different frequency. The source beams are combined and directed along a path to a bar code to be read; the return combined reflected light patterns are amplitude modulated by the bar code and are detected and the amplitude modulation of at least one of these patterns is detected to obtain a representation of the bar code read. The phase shift between the source beam and at least one of the reflected light patterns is used to determine the distance to the barcode bearing object. Distance information may be used to improve barcode reading performance.
22 Citations
17 Claims
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1. A frequency division multiplexed scanner system comprising:
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a plurality of radiation sources for simultaneously providing a plurality of source beams each having an intensity;
a modulator circuit for modulating the intensity of each source beam at a different frequency;
means for combining the source beams and directing them along a path to a bar code to be read;
means for receiving the source beams reflected from and amplitude modulated by the bar code; and
means, responsive to the source beams reflected from the bar code, for detecting the amplitude modulation of at least one of said source beams representative of the bar code read. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A frequency division multiplexed bar code scanner system comprising:
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a plurality of radiation sources for simultaneously providing a plurality of source beams each having an intensity;
a modulator circuit for modulating the intensity of each source beam at a different frequency;
means for combining the source beams and directing them along a path to a bar code bearing object;
means for receiving the source beams reflected from the object amplitude modulated by the bar code and phase shifted in accordance with the distance between the object and scanner;
means responsive to the source beams reflected from the object for detecting the amplitude modulation of at least one of said source beams representative of the bar code read and for detecting the phase shift of at least one of said source beams representative of the distance to the object from the scanner. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17)
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Specification