Ballast containing protection circuit for detecting rectification of arc discharge lamp
US5574335A · kind A · utility
76Cited by
6References
10Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Aug 2, 1994 |
| Grant date | Nov 12, 1996 |
| Priority date | — |
| Expiry date | Aug 2, 2014 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S315/05
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A ballast includes an inverter for providing an AC voltage to a discharge lamp. As the lamp approaches end-of-life, a DC voltage component develops across the lamp. The ballast includes circuitry for monitoring the condition of each of the cathodes by measuring this DC voltage component. After a predetermined increase in this DC voltage component, the inverter is disabled in order to prevent excessive heating of the cathodes. The inverter is also disabled as a result of a resonant or near resonant mode condition of a tank circuit caused by an open circuit condition or a leaking lamp.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.