Electronic ballast with controlled filament preheating using half-wave lamp current detection
US8143796B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Oct 27, 2009 |
| Grant date | Mar 27, 2012 |
| Priority date | — |
| Expiry date | Sep 16, 2030 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S315/05
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
An electronic ballast is provided for controlled preheating of filaments in a discharge lamp. A power converter has a plurality of switching elements and converts DC power from a DC power source into AC power for the lamp. A starting circuit generates a high voltage for starting the lamp. A half-wave discharge detecting circuit detects an absolute value for each polarity peak of a lamp current, calculates an asymmetrical current value from the detected peaks with respect to a predetermined current threshold, and detects a half-wave discharge of the lamp wherein an absolute value of the asymmetrical current value is equal to or more than the current threshold for a predetermined determination time. A control circuit regulates on-times for the switching elements in an filament heating operation wherein the power converting circuit provides a high output frequency for heating each filament of the discharge lamp, and further regulates the on-times to reduce half-wave discharge detected during the filament heating operation.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.