Backlight unit implementing local dimming for liquid crystal display device

• US 8,104,945 B2
• Filed: 07/08/2008
• Issued: 01/31/2012
• Est. Priority Date: 12/27/2007
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung LED Co., Ltd. (Samsung Electronics Co. Ltd.)
• Inventors: Kim, Dae Hyun, Hahm, Hun Joo, Kim, Hyung Suk, Kim, Dae Yeon
• Primary Examiner(s): CARIASO, ALAN B
• Application Number:
  US12/169,468
• Publication Number:
  US 20090168455A1
• Time in Patent Office: 1,302 Days
• Field of Search: 362 971- 974, 362/561, 362/631, 362/613, 362/608, 362/612, 362/630, 362/555, 362/231, 362/602, 362/616, 362/295, 345/102
• US Class Current: 362/631
• CPC Class Codes: G02B 6/0068 Arrangements of plural sources, e.g. multi-colour light sources
• CPC Class Codes: G02B 6/0073 Light emitting diode [LED]
• CPC Class Codes: G02B 6/0078 Side-by-side arrangements, e.g. for large area displays
• CPC Class Codes: G02F 1/133603 with LEDs
• CPC Class Codes: G02F 1/133615 Edge-illuminating devices, i.e. illuminating from the side

Abstract

A backlight unit for a liquid crystal display (LCD) device, disposed under a liquid crystal panel to illuminate the liquid crystal panel. The backlight unit includes a light guide plate, first and second light emitting diode (LED) arrays, disposed on adjacent sides, perpendicular to each other, of the light guide plate, each array having a plurality of LED blocks, consisting of one or more LEDs, and a control unit that controls electric signals, respectively inputted to the LED blocks, to regulate luminance for the respective LED blocks, wherein light emitted from the first and second LED arrays is overlapped each other in the light guide plate.

Claims

1. A backlight unit for a liquid crystal display (LCD) device, disposed under a liquid crystal panel to illuminate the liquid crystal panel, the backlight unit comprising:

a light guide plate;

first and second light emitting diode (LED) arrays disposed on adjacent sides, perpendicular to each other, of the light guide plate, each of the arrays having at least one of LED blocks, each of which consists of one or more LEDs; and

a control unit that controls electric signals, respectively inputted to the LED blocks, to regulate luminance for the respective LED blocks,

wherein light emitted from the first and second LED arrays overlaps in the light guide plate, and

wherein the control unit controls an electric signal to regulate a luminance of a first LED block of the LED blocks independently of an electric signal to regulate a luminance of a second LED block of the LED blocks.

2. The backlight unit for LCD device of claim 1, wherein the light guide plate has one or more shield structures therein for blocking light propagation.

3. The backlight unit for LCD device of claim 2, wherein the shield structure is arranged in horizontal and vertical directions with respect to the light guide plate.

4. The backlight unit for LCD device of claim 2, wherein the shield structure is a reflector film.

5. The backlight unit for LCD device of claim 2, wherein the shield structure is a bent provided on a boundary between regions divided by the same.

6. The backlight unit for LCD device of claim 1, further comprising third and fourth LED arrays, respectively disposed opposite to the first and second LED arrays on the other adjacent sides, perpendicular to each other, of the light guide plate, and having the same construction as the first and second LED arrays.

7. The backlight unit for LCD device of claim 1, wherein the LED block includes a red LED, a green LED, and a blue LED.

8. The backlight unit for LCD device of claim 1, wherein the LED block includes a white LED.

9. The backlight unit for LCD device of claim 1, wherein the control unit includes an LED block driving controller and a panel image signal transmitter.

10. The backlight unit for LCD device of claim 9, wherein the panel image signal transmitter includes a panel data transfer circuit and a panel data combination circuit.

11. The backlight unit for LCD device of claim 1, further comprising a reflector sheet under the light guide plate.

12. The backlight unit for LCD device of claim 1, further comprising an optical sheet disposed on the light guide plate.

13. The backlight unit for LCD device of claim 1, wherein the control unit receives a first image signal for a first region of the liquid crystal panel and a second image signal for a second region of the liquid crystal panel, and determines an output power of the first LED block according to the first image signal and an output power of the second LED block according to the second image signal.

20. The backlight unit for LCD device of claim 1, wherein the first LED block is of the first LED array and the second LED block is of the second LED array, and light emitted from the first LED block overlaps with light emitted from the second LED block.

14. A display device comprising:

a display panel; and

a backlight unit which irradiates light to the display panel,

wherein the backlight unit comprises;

a light guide plate;

first and second light emitting diode (LED) arrays disposed on adjacent sides, perpendicular to each other, of the light guide plate, each of the arrays having at least one of LED blocks, each of which consists of one or more LEDs; and

a control unit that controls electric signals, respectively inputted to the LED blocks, to regulate luminance for the respective LED blocks,

wherein light emitted from the first and second LED arrays overlaps in the light guide plate, and

wherein the control unit controls an electric signal to regulate a luminance of a first LED block of the LED blocks independently of an electric signal to regulate a luminance of a second LED block of the LED blocks.

15. The display device of claim 14, wherein the display panel is a liquid crystal panel.

16. The display device of claim 14 further comprising a driving circuit which drives the backlight unit.

17. A television comprising:

a display panel; and

a backlight unit which irradiates light to the display panel,

wherein the backlight unit comprises;

a light guide plate;

first and second light emitting diode (LED) arrays disposed on adjacent sides, perpendicular to each other, of the light guide plate, each of the arrays having at least one of LED blocks, each of which consists of one or more LEDs; and

a control unit that controls electric signals, respectively inputted to the LED blocks, to regulate luminance for the respective LED blocks,

wherein light emitted from the first and second LED arrays overlaps in the light guide plate, and

wherein the control unit controls an electric signal to regulate a luminance of a first LED block of the LED blocks independently of an electric signal to regulate a luminance of a second LED block of the LED blocks.

18. The television of claim 17, wherein the display panel is a liquid crystal panel.

19. The television of claim 17 further comprising a driving circuit which drives the backlight unit.