Keyboard switch
US4132487A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 16, 1977 |
| Grant date | Jan 2, 1979 |
| Priority date | — |
| Expiry date | May 16, 1997 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB41J5/08
- WIPO fieldTextile and paper machines
- WIPO sectorMechanical engineering
Abstract
This invention relates to a keyboard switch or push button transducer for use in keyboards which makes use of the advantages of resistive and capacitive methods of closure. The switch element is comprised of a resilient conductive element attached to a pad of compressible foam mounted on the end of a key plunger. When the push button or switch plunger is depressed, the switch element is brought into contact with conductive elements etched on a printed circuit board. One of the conductive elements has a coating of dielectric material thereon, and the other conductive element has a raised conductive surface to contact the conductive elastomer sheet prior to the contact with the dielectric material. The insulated area forms a capacitance between the elastomer sheet and the conductive element or metallic pad on the printed circuit board, and the other area of conductor element, being uninsulated, makes a resistive contact with the elastomer. This forms a series resistance capacitance switch capable of passing pulsed signals therethrough.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.