Keyboard circuit
US4106011A · kind A · utility
30Cited by
10References
4Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Oct 24, 1975 |
| Grant date | Aug 8, 1978 |
| Priority date | — |
| Expiry date | Oct 24, 1995 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03M11/003
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A simplified keyboard for a terminal device, calculator, or the like, in which each key is sequentially scanned and parallel key code data is sent to an entry register. A pair of flip-flops in combination with firmware ascertain that only valid key code data is sent to the entry register for utilization by the system, providing double entry and key bounce protection. The firmware further provides N-key rollover and auto repeat with a variable repeat rate, and expands the keyboard from a single-mode to an eight-mode capability.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.