Browse Prior Art Database

Delta Distance Bar Decoder

IP.com Disclosure Number: IPCOM000079809D
Original Publication Date: 1973-Sep-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Bard, SL: AUTHOR

Abstract

A pair of optical sensors combined with peak detection circuits provide a simple and reliable bar-code reader and decoder.

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Delta Distance Bar Decoder

A pair of optical sensors combined with peak detection circuits provide a simple and reliable bar-code reader and decoder.

In the figure, tag 1 is marked with a plurality of bars 2, whose spacing indicates a binary code. Equal adjacent spaces are read as a "1" and unequal adjacent spaces indicate a "0". Bars 2 are detected by two optical sensors 3, 4 spaced a distance greater than the separation of two closely spaced marks, but less than the distance of two widely spaced marks.

Sensor output signals are supplied to respective amplifiers 5, 6 and peak detector circuits 7, 8. Detector 7 provides an input to flip-flop 9 and changes the output of the flip-flop with each input signal. Only the "on" output serves as an input to shift register 10. Detector 8 is connected to single-shot circuit 11 and to shift register 10. Each output signal from detector 8 causes single-shot 11 to reset flip-flop 9, and serves as a clock gating signal for storing flip-flop data in the shift register 10.

Assuming relative movement as indicated by the arrow and mark spacing as shown, sensor 3 will produce two output signals that will set and reset flip-flop 9 before detector 4 will produce an output signal. Thus, the flip-flop will be in the 0 state at the occurrence of the gating signal to shift register 10. At the third mark detected by sensor 3, flip-flop 9 will be set and then reset by sensor 4 producing an output as it senses the second mark. The output of...