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Bar Code and Reading Technique

IP.com Disclosure Number: IPCOM000079017D
Original Publication Date: 1973-Apr-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 35K

Publishing Venue

IBM

Related People

Gaston, CA: AUTHOR

Abstract

The figure illustrates a bar code composed of wide and narrow bars, and the outputs obtained from circular disc versus ring fiber-optic sensors passed along the bar pattern. The relative dimensions of the bars are such that maximum light return is obtained between bars, minimum light return is obtained from wide bars, and partial light return is obtained when the sensor is positioned over a narrow bar. Electronic circuitry senses the dips in light output and interprets each as a "1" (full drop) or "0" (partial drop).

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Bar Code and Reading Technique

The figure illustrates a bar code composed of wide and narrow bars, and the outputs obtained from circular disc versus ring fiber-optic sensors passed along the bar pattern. The relative dimensions of the bars are such that maximum light return is obtained between bars, minimum light return is obtained from wide bars, and partial light return is obtained when the sensor is positioned over a narrow bar. Electronic circuitry senses the dips in light output and interprets each as a "1" (full drop) or "0" (partial drop).

A ring-shaped sensor produces a more convoluted output, as shown, thus permitting more sophisticated noise-rejection logic in sensing 0 bits. Logic may be designed to test for the minimum-maximum-minimum pattern of a narrow bar as detected by a ring sensor, and to reject extraneous local extrema. A 1 output occurs if one or more "low" local minima are detected between "highs". A 0 output occurs only if a minimum-maximum-minimum pattern occurs between two highs, and is unaccompanied by a low.

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