Browse Prior Art Database

Keyboard With Programmable Threshold Setting

IP.com Disclosure Number: IPCOM000053118D
Original Publication Date: 1981-Sep-01
Included in the Prior Art Database: 2005-Feb-12
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Aaron, RT: AUTHOR

Abstract

Electronic keyboards utilizing capacitive sensing are susceptible to signal degradation caused by dust resulting in intermittent failures which are difficult to isolate by service personnel. By building in a programmable key sensing threshold, service personnel may readily check for marginal operation causing intermittent errors to become continuous errors.

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Keyboard With Programmable Threshold Setting

Electronic keyboards utilizing capacitive sensing are susceptible to signal degradation caused by dust resulting in intermittent failures which are difficult to isolate by service personnel. By building in a programmable key sensing threshold, service personnel may readily check for marginal operation causing intermittent errors to become continuous errors.

Utilizing a conventional sense amplifier with a programmable threshold, a fixed key sensing threshold is set during normal power-on operations, as indicated at 11. If at this time a designated trigger key is held down, then a special routine is entered for programming a threshold level. Thus, the trigger key is sampled, as indicated at 13, and if it is not depressed, normal keyboard scanning thereafter takes effect, as indicated at 15. If the trigger key is depressed, then the states of three other designated keys are sampled, as indicated at 17, to input a binary threshold value to the sense amplifier, as indicated at 19. If a solid error now appears during normal keyboarding, it is then known that it is a keyboard problem rather than a problem in the sensing electronics.

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