Lamp controller with lamp status detection and safety circuitry
US5751115A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 3, 1996 |
| Grant date | May 12, 1998 |
| Priority date | — |
| Expiry date | Dec 3, 2016 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S315/05
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A ballast includes safety circuitry which senses lamp status through various phases of ballast operation. According to one feature, the ballast is prevented from supplying an output voltage upon initial energization of the ballast when a lamp is not present at the output terminals. The presence of a filament is sensed via a DC path extending through the filament heater windings of an output transformer. When the DC path is not complete, a control input, for example the power supply input of the ballast controller, is not provided with a voltage to start ballast operation. The DC path is also used to restart the ballast if a defective lamp is replaced with a good one. Over-voltage and capacitive mode detection is also disclosed to shut down ballast output upon lamp failure/removal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.