Keyboard membrane switch having threshold force structure
US4017697A · kind A · utility
140Cited by
9References
17Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Sep 15, 1975 |
| Grant date | Apr 12, 1977 |
| Priority date | — |
| Expiry date | Sep 15, 1995 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01H2229/016
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A keyboard membrane switch including the standard three layer resilient flexible diaphragm switch construction. Threshold pressure is applied to the membrane prior to engagement of the membrane contact with at least one fixed contact. This phenomenon is achieved by applying variable thicknesses of nonconductive threshold paint or glass to the substrate, flexible membrane, a first layer of threshold material or any combination thereof.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.