Backlight unit

• US 7,905,618 B2
• Filed: 07/18/2008
• Issued: 03/15/2011
• Est. Priority Date: 07/19/2007
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung LED Co., Ltd. (Samsung Electronics Co. Ltd.)
• Inventors: Kim, Dae Yeon, Hahm, Hun Joo, Shin, Jae Hong, Shin, Chang Ho, Jeong, Young June
• Primary Examiner(s): Husar; Stephen F
• Application Number:
  US12/175,952
• Publication Number:
  US 20090021932A1
• Time in Patent Office: 970 Days
• Field of Search: 362/97.3, 362/231, 362/249.02, 362/612, 362/218, 362/294, 362/373, 362/800
• US Class Current: 362/97.3
• CPC Class Codes: F21K 9/00 Light sources using semiconductor devices as light-generating elements, e.g. using light-emitting diodes [LED] or lasers
• CPC Class Codes: F21K 9/60 Optical arrangements integrated in the light source, e.g. for improving the colour rendering index or the light extraction
• CPC Class Codes: G02F 1/133603 with LEDs
• CPC Class Codes: G02F 1/133614 using photoluminescence, e.g. phosphors illuminated by UV or blue light
• CPC Class Codes: G02F 1/133628 with cooling means
• CPC Class Codes: H05K 1/142 Arrangements of planar printed circuit boards in the same plane, e.g. auxiliary printed circuit insert mounted in a main printed circuit

Abstract

Provided is a backlight unit including a plurality of light emitting diodes (LEDs) that emit light; a plurality of LED modules having a printed circuit board (PCB) which supports and drives the plurality of LEDs; a plurality of optical sheets that are attached to the top surfaces of the respective LED modules; and a plurality of heat radiating pads that are attached to the rear surfaces of the respective LED modules.

Claims

1. A backlight unit comprising:

a plurality of light emitting diodes (LEDs) that emit light;

a plurality of LED modules having a printed circuit board (PCB) which supports and drives the plurality of LEDs;

a plurality of optical sheets that are attached to the top surfaces of the respective LED modules; and

a plurality of heat radiating pads that are attached to the rear surfaces of the respective LED modules,

wherein the optical sheet and the heat radiating pad have the same size as the LED module or a smaller size than the LED module, and

the LED modules are arranged in parallel to each other in the longitudinal direction thereof.

2. The backlight unit according to claim 1, wherein the LED modules are arranged so as to surround a predetermined region.

3. The backlight unit according to claim 1, wherein the plurality of LEDs are continuously arranged in a triangle or rectangle shape.

4. The backlight unit according to claim 1, wherein the plurality of LEDs are separated for each block in a circuit manner such that some LEDs among the plurality of LEDs can be partially turned on/off.

5. A backlight unit comprising:

a plurality of LEDs that emit light; and

a plurality of LED modules having a printed circuit board (PCB) which supports and drives the plurality of LEDs,

wherein the plurality of LED modules include a plurality of white LEDs arranged in a matrix shape composed of two or more rows and two or more columns and a center luminous intensity of an LED unit composed of arbitrary LEDs which are disposed at the shortest distance from each other corresponds to 80 to 120% of the average of luminous intensities of the LEDs, and

the plurality of LEDs are continuously arranged in a triangle shape and a distance between first and second LEDs, which are disposed in the same column and are adjacent to each other, is set in the range of 20 to 140 mm.

6. The backlight unit according to claim 5, wherein the plurality of LED modules are divided into a plurality of blocks which are separated from each other through printing circuit patterns in a circuit manner so as to be independently turned on/off.

7. A backlight unit comprising:

a plurality of LED modules having a plurality of LEDs that emit white light and a printed circuit board (PCB) which supports and drives the plurality of LEDs,

wherein the plurality of LEDs include;

an LED chip having a dominant wavelength of 420-456 nm;

red phosphors which are disposed around the LED chip and are excited by the LED chip so as to emit red light; and

green phosphors which are disposed around the LED chip and are excited by the LED chip so as to emit green light, and

wherein the plurality of LED modules are at least four or more in number and are arranged so as to surround a predetermined region, and

the red phosphors include a nitride-based red phosphor.

8. The backlight unit of claim 7, wherein the red phosphors include a nitride-based CaAlSiN3:

Eu red phosphor.

9. A backlight unit comprising:

a plurality of LED modules having a plurality of LEDs that emit white light and a printed circuit board (PCB) which supports and drives the plurality of LEDs,

wherein the plurality of LEDs include;

an LED chip having a dominant wavelength of 420-456 nm;

red phosphors which are disposed around the LED chip and are excited by the LED chip so as to emit red light; and

green phosphors which are disposed around the LED chip and are excited by the LED chip so as to emit green light, and

wherein the plurality of LED modules are at least four or more in number and are arranged so as to surround a predetermined region, and

the green phosphors include any one of silicate-based green phosphor, and a nitride-based green phosphor.

10. The backlight unit of claim 9, wherein the green phosphors include any one of a silicate-based green phosphor having a composition of A2SiO4 or A3SiO5, and a nitride-based green phosphor having a composition of Beta-SiAlON, wherein A may be Sr, Ba, Ca, and Mg, and Sr is an essential element, and Ba, Ca, and Mg are selectively included, if necessary, and are satisfied by 0<

sum of composition of Ba, Ca, Mg<

1.

11. A display device comprising:

a display panel; and

a backlight unit which irradiates light to the display panel,

wherein the backlight unit comprises;

a plurality of light emitting diodes (LEDs) that emit light;

a plurality of LED modules having a printed circuit board (PCB) which supports and drives the plurality of LEDs;

a plurality of optical sheets that are attached to the top surfaces of the respective LED modules; and

a plurality of heat radiating pads that are attached to the rear surfaces of the respective LED modules,

wherein the optical sheet and the heat radiating pad have the same size as the LED module or a smaller size than the LED module, and

the LED modules are arranged in parallel to each other in the longitudinal direction thereof.

12. The display device of claim 11, wherein the display panel is a liquid crystal panel.

13. The display device of claim 11, further comprising a driving circuit which drives the backlight unit.

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 plurality of LEDs that emit light; and

a plurality of LED modules having a printed circuit board (PCB) which supports and drives the plurality of LEDs,

wherein the plurality of LED modules include a plurality of white LEDs arranged in a matrix shape composed of two or more rows and two or more columns and a center luminous intensity of an LED unit composed of arbitrary LEDs which are disposed at the shortest distance from each other corresponds to 80 to 120% of the average of luminous intensities of the LEDs, and

the plurality of LEDs are continuously arranged in a triangle shape and a distance between first and second LEDs, which are disposed in the same column and are adjacent to each other, is set in the range of 20 to 140 mm.

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 display device comprising:

a display panel; and

a backlight unit which irradiates light to the display panel,

wherein the backlight unit comprises;

a plurality of LED modules having a plurality of LEDs that emit white light and a printed circuit board (PCB) which supports and drives the plurality of LEDs,

wherein the plurality of LEDs include;

an LED chip having a dominant wavelength of 420-456 nm;

red phosphors which are disposed around the LED chip and are excited by the LED chip so as to emit red light; and

green phosphors which are disposed around the LED chip and are excited by the LED chip so as to emit green light, and

wherein the plurality of LED modules are at least four or more in number and are arranged so as to surround a predetermined region, and

the red phosphors include a nitride-based red phosphor.

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

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

20. A display device comprising:

a display panel; and

a backlight unit which irradiates light to the display panel,

wherein the backlight unit comprises;

a plurality of LED modules having a plurality of LEDs that emit white light and a printed circuit board (PCB) which supports and drives the plurality of LEDs,

wherein the plurality of LEDs include;

an LED chip having a dominant wavelength of 420-456 nm;

red phosphors which are disposed around the LED chip and are excited by the LED chip so as to emit red light; and

green phosphors which are disposed around the LED chip and are excited by the LED chip so as to emit green light; and

wherein the plurality of LED modules are at least four or more in number and are arranged so as to surround a predetermined region, and

the green phosphors include any one of silicate-based green phosphor and a nitride-based green phosphor.

21. The display device of claim 20, wherein the display panel is a liquid crystal panel.

22. The display device of claim 20, further comprising a driving circuit which drives the backlight unit.