Keyboard having keys activated by electrical contacts and the capacity to read one state from among four possible states
US4502040A · kind A · utility
3Cited by
7References
3Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Jun 23, 1982 |
| Grant date | Feb 26, 1985 |
| Priority date | — |
| Expiry date | Jun 23, 2002 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03M11/00
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A keyboard having keys activated by electrical contacts and the capacity to read one state from among four possible states, wherein the keyboard is a dipole disposed between two terminals between which are positioned in parallel three connectors, each including one of the electrical contacts, two of these connectors including diodes mounted anode to cathode, in such a way that the various states may be discriminated by means of the successive application of two reverse electrical voltages (V1, V2) to the terminals of the dipole and the corresponding detection of the logic states of the contacts using a logic detector.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.