Method and apparatus for controlling minimum brightness of a flourescent lamp
US6469922B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Sep 4, 2001 |
| Grant date | Oct 22, 2002 |
| Priority date | — |
| Expiry date | Sep 4, 2021 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S315/04
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
An efficient power conversion circuit for driving a fluorescent lamp uses a minimum pulse generator circuit to control the minimum on-time of a time modulated signal to increase the dimming range of the fluorescent lamp operating over a wide range of temperature and supply voltage. A minimum number of lamp current cycles with respective amplitudes above a preset threshold is typically required to avoid flickering or shimmering during minimum brightness. The minimum pulse generator circuit counts the lamp current cycles and adjusts the on-time accordingly to guarantee the minimum number of cycles with respective amplitudes above a preset threshold under all operating conditions.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.