Switch matrix key closure validation device and method
US4581603A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 11, 1983 |
| Grant date | Apr 8, 1986 |
| Priority date | — |
| Expiry date | Mar 11, 2003 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03M11/003
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A keyboard or switch matrix key closure validation device and method for a terminal, calculator, desktop computer, or the like is described. The keyboard or switch matrix consists of a matrix of momentary switching elements on "keys" whose number is larger than the number of rows or number of columns in the matrix. A microprocessor provides sequential scanning of the keys in the matrix. The microprocessor also provides detection of closed keys. Upon such detection the microprocessor performs a test for protection against pseudo keys, a debounce test and a detease test. Pseudo key protection is accomplished without each matrix key location having an associated isolation diode. Debounce testing is performed with an extendable bounce period.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.