Electronic logic to enhance switch reliability in detecting openings and closures of redundant switches
US4626708A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 20, 1984 |
| Grant date | Dec 2, 1986 |
| Priority date | — |
| Expiry date | Jan 20, 2004 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03K19/20
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A logic circuit is used to enhance redundant switch reliability. Two or more switches are monitored for logical high or low output. The output for the logic circuit produces a redundant and failsafe representation of the switch outputs. When both switch outputs are high, the output is high. Similarly, when both switch outputs are low, the logic circuit's output is low. When the output states of the two switches do not agree, the circuit resolves the conflict by memorizing the last output state which both switches were simultaneously in and produces the logical complement of this output state. Thus, the logic circuit of the present invention allows the redundant switches to be treated as if they were in parallel when the switches are open and as if they were in series when the switches are closed. A failsafe system having maximum reliability is thereby produced.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.