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Switch Contact Debounce Technique

IP.com Disclosure Number: IPCOM000079046D
Original Publication Date: 1973-Apr-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 29K

Publishing Venue

IBM

Related People

Woo, EK: AUTHOR

Abstract

This is an efficient control circuit to mask off any electrical-mechanical switch contact bounce.

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Switch Contact Debounce Technique

This is an efficient control circuit to mask off any electrical-mechanical switch contact bounce.

A single-shot 20 is controlled by AND gates 12 and 14. The circuit is initially energized by the closure of switch 16. This satisfies the input requirements of gate 12, resulting in the input to the single-shot 20 going negative and firing single-shot 20. The output of single-shot 20 then goes negative, setting latch 18. As a result, the output of latch 18 goes negative, turning gate 12 off. When the downtime of single-shot 20 expires, the input to trigger 22 turns trigger 22 on. This results in output 24 going positive and output 26 going negative. Output 26 being negative, turns off latch 18 and gate 12. With this the input requirement of gate 28 is satisfied, output 26 providing a delayed output.

Switch 16 then opens and switch 30 closes. Input gate 14 is now satisfied, firing single-shot 20. Output of single-shot 20 again sets latch 18 resulting in both gates 14 and 28 being turned off. As the single-shot expires for the second time, it forces binary trigger 22 off and restores the circuit to its initial condition.

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