Method and apparatus for controlling a discharge lamp in a backlighted display
US7911150B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 22, 2009 |
| Grant date | Mar 22, 2011 |
| Priority date | — |
| Expiry date | May 19, 2029 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05B41/3927
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
The described DC to AC inverter efficiently controls the amount of electrical power used to drive a cold cathode fluorescent lamp (CCFL). The output is a fairly pure sine wave which is proportional to an input control voltage. The output waveform purity is ensured by driving a symmetrical rectangular waveform into a second-order, low pass filter at the resonant frequency of the filter for all conditions of line voltage and delivered power. Operating stress on the step-up transformer is minimized by placing the load (lamp) directly across the secondary side of the transformer. When configured to regulate delivered power, the secondary side may be fully floated which practically eliminates a thermometer effect on the operation of the lamp. All of the active elements, including the power switches, may be integrated into a monolithic silicon circuit.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.