Dimming method and device for fluorescent lamps used for backlighting of liquid crystal screens
US5105127A · kind A · utility
214Cited by
4References
8Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Jun 21, 1990 |
| Grant date | Apr 14, 1992 |
| Priority date | — |
| Expiry date | Jun 21, 2010 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S315/04
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A dimming device, with a brightness dimming ratio of 1 to 1000, for a fluorescent lamp used for the backlighting of a liquid crystal screen comprises a periodic signal generator for delivering rectangular pulses with an adjustable duty cycle. The pulses are synchronized with the image synchronizing signal of the liquid crystal screen. An alternating voltage generator provides power to the lamp only during the pulses. The decrease in tube efficiency for very short pulses allows the required dimming intensity to be achieved without image flickering.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.