Low power switch closure sensing circuit
US4303907A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 17, 1979 |
| Grant date | Dec 1, 1981 |
| Priority date | — |
| Expiry date | Dec 17, 1999 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03M11/22
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A matrix array of row and column conductors, electrically isolated from each other, with a key switch connected between a row and a column conductor at each intersection of a row and a column conductor. Each column conductor is connected to a normally non-conducting current sourcing circuit and each row conductor is connected to a normally non-conducting current sinking circuit. Each key switch, when closed, connects its associated row and column conductors causing current to flow between that column's current sourcing circuit and that row's current sinking circuit. The current sourcing and the current sinking circuits associated with the particular switch closure then produce signals indicative of that key switch closure.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.