Title:
SYSTEM FOR OVERVOLTAGE PROTECTION DURING PULSE WIDTH MODULATION DIMMING OF AN LCD BACKLIGHT INVERTER
Document Type and Number:
WIPO Patent Application WO2002021885
Kind Code:
A3
Abstract:
A system and method for providing overvoltage protection during a pulse width modulation (PWM) dimming of a liquid crystal display (LCD) backlight inverter are provided. The disclosed system achieves overvoltage protection by providing two low voltages (or current) signals: an output voltage sensing signal and a protection trigger threshold signal. The output voltage sensing signal represents the ballast output voltage. The output voltage sensing and protection trigger threshold voltage signals are inputted into a comparator and overvoltage protection is activated if the output voltage sensing signal is higher than the protection trigger threshold voltage signal during a predetermined time interval.
Inventors:
LI YUSHAN
Application Number:
PCT/EP2001/009929
Publication Date:
July 04, 2002
Filing Date:
August 27, 2001
Export Citation:
Assignee:
KONINKL PHILIPS ELECTRONICS NV (NL)
International Classes:
H05B41/24; H05B41/285; H05B41/392; (IPC1-7): H05B41/392; H05B41/292
Domestic Patent References:
| WO1990007787A1 | 1990-07-12 | |||
| WO2000038483A1 | 2000-06-29 |
Foreign References:
| US5384516A | 1995-01-24 | |||
| US4670705A | 1987-06-02 | |||
| US5680034A | 1997-10-21 |
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