Electronic ballast with filament cut-out
US5973455A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 15, 1998 |
| Grant date | Oct 26, 1999 |
| Priority date | — |
| Expiry date | May 15, 2018 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S315/07
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
An electronic ballast for a gas discharge lamp includes an AC to DC converter for changing alternating current at power line voltage to direct current and an inverter powered by the converter and having a series resonant, direct coupled output coupled to the lamp. The inverter includes an AC switch having a diode bridge defining an AC diagonal and a DC diagonal and a transistor connected across the DC diagonal. The primary winding of a filament transformer is connected across the AC diagonal of the bridge and the transistor is coupled to the microprocessor for controlling current through the primary winding. The microprocessor is programmed to close the AC switch while the lamp is starting and to open the switch after the lamp is started, thereby cutting off the filaments from a source of power and reducing the power consumed by the ballast during normal operation. A resistor in series with the transistor is used to detect filament resistance and provide an indication of lamp type.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.