Current-preheat electronic ballast and resonant capacitor adjusting circuit thereof
US8760059B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 2, 2012 |
| Grant date | Jun 24, 2014 |
| Priority date | — |
| Expiry date | Sep 19, 2032 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05B41/2827
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A current-preheat electronic ballast includes an AC-to-DC converter, a controlling unit, an auxiliary voltage generator, and an inverter. The inverter is connected with the DC bus for converting a high DC voltage into an AC output voltage and generating a resonant current and a lamp filament current to a lamp group. The inverter includes a resonant circuit and a resonant capacitor adjusting circuit. The resonant circuit provides electric energy required to preheat the lamp group. The resonant capacitor adjusting circuit judges whether the inverter is enabled according to the detecting element. After the inverter has been enabled for a delayed time, two high-voltage switching terminals of the resonant capacitor adjusting circuit are correspondingly conducted or shut off, so that an equivalent resonant capacitance value of the resonant circuit is changed and a voltage drop across two ends of a lamp filament of the lamp group is changed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.