Contactless keyswitch for keyboards
US4117438A · kind A · utility
19Cited by
7References
12Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Apr 13, 1977 |
| Grant date | Sep 26, 1978 |
| Priority date | — |
| Expiry date | Apr 13, 1997 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01F29/12
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
Inductive sensing keyswitch includes a printed circuit transformer and sheet of material having hinged metal flaps formed therein and each flap is resiliently biased against both printed circuit coils of the transformer for eddy-current shorting of both coils wherein keys on the keyboard have key stems passing through the printed circuit board between the printed coils and the flap hinges to provide a mechanical advantage for moving the flaps away from the printed circuit coils a greater distance than the short stroke movement of the key.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.