Method and apparatus for independent control of brightness and color balance in display and illumination systems
US6618031B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 26, 1999 |
| Grant date | Sep 9, 2003 |
| Priority date | — |
| Expiry date | Feb 26, 2019 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02B20/30
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A drive circuit for a time sequential color LED based display device allows the overall brightness of a display device to be adjusted without affecting the color balance. The circuit includes a boost switching converter, which provides constant power to each of a plurality of different colored LEDs associated with a pixel, independent of the forward voltage across each LED. The boost switching converter receives a pulse width modulated drive signal for activating each LED, when enabled, during a frame. The on-time of the drive signal varies during each frame according to which LED is to be activated at a particular point in time, to provide the appropriate power to the LED. The LEDs are enabled sequentially during a frame by separate enable signals. The cathode of each LED is connected to a positive power supply voltage when the LED is enabled.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.