LIQUID CRYSTAL DISPLAY DEVICE

• US 20150102748A1
• Filed: 10/08/2014
• Published: 04/16/2015
• Est. Priority Date: 10/10/2013
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Display Co., Ltd.
• Inventors: LEE, Jae-Ho
• Granted Patent: US 9,232,599 B2
• Time in Patent Office: Days
• US Class Current: 315/297
• CPC Class Codes: F21K 9/64 using wavelength conversion means distinct or spaced from the light-generating element, e.g. a remote phosphor layer
• CPC Class Codes: G02F 1/133603 with LEDs
• CPC Class Codes: G02F 1/133609 including means for improving the color mixing, e.g. white
• CPC Class Codes: G02F 1/133612 Electrical details
• CPC Class Codes: G02F 1/133621 providing coloured light G02F1/133617, G02F1/133533 take precedence
• CPC Class Codes: H05B 45/28 using temperature feedback

Abstract

A liquid crystal display device includes a backlight unit including an LED assembly, wherein the LED assembly includes: a plurality of LED packages; an LED PCB on which the plurality of LED packages are arranged being spaced apart from each other; and an LED driving circuit board that is connected to the LED PCB and includes a LED driving circuit, wherein the LED package includes first and second LED chips emitting two colors, respectively, out of red, green and blue, and a fluorescent substance emitting the other one color out of the red, green and blue, wherein a temperature sensor is formed in the LED PCB, and wherein the first or second LED chip is supplied with a compensated voltage according to temperature change by the temperature sensor.

Claims

1. A liquid crystal display device, comprising:

a backlight unit including an LED assembly,

wherein the LED assembly includes;

a plurality of LED packages;

an LED PCB on which the plurality of LED packages are arranged being spaced apart from each other; and

an LED driving circuit board that is connected to the LED PCB and includes a LED driving circuit,

wherein the LED package includes first and second LED chips emitting two colors, respectively, out of red, green and blue, and a fluorescent substance emitting the other one color out of the red, green and blue,

wherein a temperature sensor is formed in the LED PCB, and

wherein the first or second LED chip is supplied with a compensated voltage according to temperature change by the temperature sensor.

2. The device of claim 1, wherein the first LED chips emits the blue, the second LED chip emits the red, and the fluorescent substance emits the green.

3. The device of claim 2, wherein a full width at half maximum (FWHM) of light emission of the fluorescent substance is about 70 nm or less.

4. The device of claim 2, wherein the LED driving circuit includes a PWM control IC, a DC-DC block, and an LED sensing portion,

wherein the LED sensing portion includes first and second LED sensing portions that each include a plurality of resistors, and are connected to the first and second LED chips, respectively, and

wherein the temperature sensor is connected to the second LED sensing portion.

5. The device of claim 4, wherein the second LED sensing portion includes the plurality of resistors and the temperature sensor, and

wherein a resistance value of the temperature sensor is varied proportional to a temperature measured.

6. The device of claim 4, wherein the DC-DC block supplies DC powers to the first and second LED chips independently,

wherein the PWM control IC controls an output current of the DC-DC block, and

wherein the LED sensing portion feeds output voltages of the first and second LED chips back to the PWM control IC

7. The device of claim 1, wherein a resistance value of the temperature sensor is varied proportional to temperature change of the first or second LED chip.

8. The device of claim 7, wherein a driving voltage supplied to the first or second LED chip rises as a measured temperature value of the temperature sensor is higher.