Lamp monitoring circuit
US4572987A · kind A · utility
6Cited by
4References
8Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Mar 7, 1984 |
| Grant date | Feb 25, 1986 |
| Priority date | — |
| Expiry date | Mar 7, 2004 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R31/2829
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
In order to provide a lamp failure warning in both illuminated and unilluminated states of the lamp, there is provided a resistance bridge circuit Rs, L, R2 and R3 which is substantially in balance if the lamp L is sound. An amplifier IC1 acts as a detection means if the bridge goes out of balance as a consequence of failure of the lamp L. In the unilluminated state a reduced current is fed to the bridge via a high value resistance R1, which is by-passed by a lamp switch SW1 if the lamp is to receive enough power to illuminate it.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.