Light emitting diode driving circuit for backlight having constant current control function
US7564434B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Jun 29, 2006 |
| Grant date | Jul 21, 2009 |
| Priority date | — |
| Expiry date | Feb 29, 2028 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02B20/30
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
An LED driving circuit of a backlight unit includes a switch connected between an input of direct voltage and a ground to switch the direct voltage according to a switching pulse; a rectifying diode connected between a connecting node and one terminal of the LED array to rectify driving voltage supplied according to switching operation of the switch; a smoothing capacitor having one terminal connected to a cathode of the rectifying diode and the other terminal connected to a ground; a voltage detecting resistor connected between the other terminal of the LED array connected to the ground and the other end of the smoothing capacitor to detect voltage from the current flowing to the ground; and a PWM controlling part for controlling on/off status of the switching according to the switching pulse, wherein the switching pulse has a duty ratio determined according to a preset internal reference voltage and the voltage detected by the voltage detecting resistor. The driving current of can be controlled at a constant current and thus be stabilized.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.