Electronic ballast that monitors direct current through lamp filaments
US5747941A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 7, 1995 |
| Grant date | May 5, 1998 |
| Priority date | — |
| Expiry date | Dec 7, 2015 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S315/05
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
An electronic ballast includes an inverter producing pulses having a DC component, an output circuit connecting the filaments of one or more lamps in series, and a control circuit for detecting direct current through the filaments. The control circuit includes a capacitor charged by the DC component. When the voltage on the capacitor reaches a predetermined value, the ballast applies a high voltage to the lamps. The predetermined value is not reached unless a direct current passes from the output of the inverter through all lamp filaments to the capacitor. If a lamp filament is not intact, the inverter will not apply high voltage to the lamp.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.