Key interface circuit with reduced number of input terminals
US6075390A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 30, 1998 |
| Grant date | Jun 13, 2000 |
| Priority date | — |
| Expiry date | Apr 30, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03M11/24
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A static key interface circuit has an input terminal coupled to N key switches, where N is an integer greater than one. The N key switches are biased at different potentials, which are supplied to the input terminal when the key switches are closed. A multilevel detector in the key interface circuit detects the potential of the input terminal and generates corresponding result data. A dynamic key interface circuit has an input terminal coupled to P rows of N key switches each and scans the P rows in turn, using a similar multilevel detector. The multilevel detector increases the number of key switches connectable to a single input terminal by a factor of N.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.