Dimmable backlight system
US6198234A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 9, 1999 |
| Grant date | Mar 6, 2001 |
| Priority date | — |
| Expiry date | Jun 9, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05B41/3927
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A dimmable, backlight system provides increased light output at low temperatures and provides a full range of dimming. Both current amplitude control and current duty cycle control are used to more precisely adjust the lamp light output. During low temperatures, the lamp is overdriven using a high amplitude current source. The increased current provides increased light output at low temperatures. When the lamp temperature increases, the amount of current flowing to the lamp is reduced to prevent damage from occurring to the lamp. The lamp may be dimmed throughout the entire temperature range by adjusting the duty cycle of the current source. By dimming using the duty cycle, the light output of the lamp may be more precisely controlled. The amplitude and duty cycle may be controlled using either an analog or digital control signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.