IP Library Granted Patent US 8,659,534
Granted Patent B2
US 8,659,534 · App. 11/894,833 · Granted Feb 25, 2014

Backlight driving apparatus

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Quick Facts
Patent No.
US 8,659,534
App. No.
11/894,833
Granted
Feb 25, 2014
Kind
B2
Abstract

A backlight driving apparatus is disclosed which is capable of simplifying a circuit configuration for driving of a plurality of light emitting diode arrays and making the current balance of the light emitting diode arrays uniform. The backlight driving apparatus includes n light emitting diode arrays that include a plurality of light emitting diodes connected in series, a power source for generating a driving current, a current generator for generating currents to drive the light emitting diode arrays using the driving current, respectively, and a current mirror circuit for allowing substantially the same amount of currents to flow respectively through the light emitting diode arrays based on current from any one of the n light emitting diode arrays.

Claims (21)

1. A backlight driving apparatus comprising:

a plurality of light emitting diode arrays including a plurality of light emitting diodes connected in series;

a power source for generating a driving current;

a current generator for generating currents to drive the light emitting diode arrays using the driving current, respectively, wherein the current generator comprises a plurality of first choke coils connected between the power source and the light emitting diode arrays and compensates for an impedance difference between the light emitting diode arrays;

a base current generator for generating a plurality of base currents using a current from any one of the light emitting diode arrays; and

a current mirror circuit for allowing the same amount of currents to flow respectively through the light emitting diode arrays based respectively on the base currents,

wherein the base current generator comprises a plurality of second choke coils connected between any one of the light emitting diode arrays and the current mirror circuit,

wherein a plurality of second choke coils:

generate the plurality of base currents based on a first current flowing through the any one the light emitting diode arrays,

respectively supply the plurality of base currents to a plurality of base terminals as control terminals of transistors of the current mirror circuit,

have a plurality of first terminals which are commonly connected with the any one of the light emitting diode arrays, and

have a plurality of second terminals which are respectively connected with the plurality of base terminals of transistors of the current mirror circuit.

2. The backlight driving apparatus according to claim 1 , further comprising a plurality of resistors disposed between the light emitting diode arrays and the base current generator and each connected between adjacent the light emitting diode arrays.

3. The backlight driving apparatus according to claim 1 , wherein the first choke coils of the current generator have first terminals connected in common to an output terminal of the power source and second terminals connected respectively to the light emitting diode arrays.

4. The backlight driving apparatus according to claim 3 , wherein the first choke coils have the same turn ratio or different turn ratios and the second choke coils have the same turn ratio or different ratios.

5. The backlight driving apparatus according to claim 1 , wherein the current mirror circuit comprises a plurality of mirror transistors controlled by the base currents from the second choke coils, respectively, and each connected between light emitting diode arrays and a ground voltage source.

6. The backlight driving apparatus according to claim 5 , further comprising a controller for controlling the power source based on feedback of the current flowing to the ground voltage source from each of the mirror transistors.

7. The backlight driving apparatus according to claim 1 , wherein the current mirror circuit comprises:

a first current mirror including a plurality of first mirror transistors controlled by the base currents from the second choke coils, respectively, and each connected between the light emitting diode arrays and the ground voltage source;

a second current mirror including a plurality of second mirror transistors controlled by the base currents from the second choke coils, respectively, and connected in parallel to the n first mirror transistors, respectively; and

a third current mirror including a plurality of transistors controlled by the base currents from the second choke coils, respectively, and connected in parallel to the n first and second mirror transistors, respectively.

Assignments (2)
CHANGE OF NAME Recorded May 22, 2008
From: LG PHILIPS CO., LTD.
To: LG DISPLAY CO., LTD.
Reel/Frame 020976/0785 →
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded Aug 22, 2007
From: KIM, PU JIN; KIM, SEUNG HYUN
To: LG PHILIPS LCD CO., LTD.
Reel/Frame 019765/0996 →