Surface light source using white light emitting diodes and liquid crystal display backlight unit having the same

• US 8,182,106 B2
• Filed: 03/11/2011
• Issued: 05/22/2012
• Est. Priority Date: 08/27/2007
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung LED Co., Ltd. (Samsung Electronics Co. Ltd.)
• Inventors: Shin, Jae Hong, Hahm, Hun Joo, Kim, Hyung Suk, Shin, Chang Ho, Kim, Dae Yeon, Yoo, Chul Hee, Cho, Dong Hyun
• Primary Examiner(s): SEMBER, THOMAS M
• Application Number:
  US13/045,946
• Publication Number:
  US 20110157492A1
• Time in Patent Office: 438 Days
• Field of Search: 362/230, 362/231, 362/249.02, 362/249.06, 362/249.14, 362/84, 362 971- 973, 362/293, 349 61- 64, 313/500, 313/502
• US Class Current: 362/97.3
• CPC Class Codes: G02F 1/133603 with LEDs
• CPC Class Codes: G02F 1/133606 including a specially adapted diffusing, scattering or light controlling members
• CPC Class Codes: G02F 1/133611 including means for improving the brightness uniformity
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 3/3413 Details of control of colour illumination sources
• CPC Class Codes: G09G 3/3426 the different display panel areas being distributed in two dimensions, e.g. matrix

Abstract

There is provided a surface light source using white light emitting diodes including: a plurality of white light emitting diodes arranged at a predetermined distance from one another, wherein the white light emitting diodes are arranged such that a light emitting diode unit defined by each of the white light emitting diodes and corresponding ones of the white light emitting diodes disposed at a closest distance from the each white light emitting diode has a central light amount ranging from 80% to 120% with respect to an average light amount of the white light emitting diodes.

Claims

1. A light source using white light emitting diodes comprising:

a plurality of white light emitting diodes arranged at a predetermined distance from one another,

wherein the white light emitting diodes are arranged such that a light emitting diode unit defined by each of the white light emitting diodes and a corresponding one of the white light emitting diodes disposed at a closest distance from the each white light emitting diode has a central light amount ranging from 80% to 120% with respect to an average light amount of the white light emitting diodes, and

the white light emitting diode comprises a blue light emitting diode chip having a dominant wavelength of 430 to 456 nm, a red phosphor emitting red light and a green phosphor emitting green light,

wherein the red light emitted from the red phosphor has a color coordinate falling within a space defined by four coordinate points (0.6448, 0.4544), (0.8079, 0.2920), (0.6427, 0.2905) and (0.4794, 0.4633) based on the CIE 1931 chromaticity diagram, and

the green light emitted from the green phosphor has a color coordinate falling within a space defined by four coordinate points (0.1270, 0.8037), (0.4117, 0.5861), (0.4197, 0.5316) and (0.2555, 0.5030) based on the CIE 1931 chromaticity diagram.

2. The light source of claim 1, further comprising a diffusing sheet, wherein the central light amount is measured at the diffusing sheet disposed on a surface of the light source.

3. The light source of claim 1, wherein the red phosphor is represented by one of CaAlSiN₃:

Eu and (Ca, Sr)S;

Eu.

4. The light source of claim 1, wherein the green phosphor is represented by one of (Ba_x, Sr_y, Mg_z)SiO₄:

Eu²⁺, F, Cl, where 0<

x, y≦

2, 0≦

z≦

2, 0 ppm≦

F, Cl≦

5000000 ppm, SrGa₂S₄;

Eu and β

-SiAlON.

5. A liquid crystal display backlight unit comprising:

a plurality of light emitting diode modules each comprising a conductive board having at least one first connector and a plurality of second connectors formed thereon, and white light emitting diode chips mounted on the conductive board, wherein;

the white light emitting diode chips are arranged at a predetermined distance from one another, and

the white light emitting diodes are arranged such that a light emitting diode unit defined by each of the white light emitting diodes and a corresponding one of the white light emitting diodes disposed at a closest distance from the each white light emitting diode has a central light amount ranging from 80% to 120% with respect to an average light amount of the white light emitting diodes.

6. The liquid crystal display backlight unit of claim 5 further comprising a diffusing sheet, wherein the central light amount is measured at the diffusing sheet.

7. 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 white light emitting diodes arranged at a predetermined distance from one another,

wherein the white light emitting diodes are arranged such that a light emitting diode unit defined by each of the white light emitting diodes and a corresponding one of the white light emitting diodes disposed at a closest distance from each white light emitting diode has a central light amount ranging from 80% to 120% with respect to an average light amount of the white light emitting diodes, and

the white light emitting diode comprises a blue light emitting diode chip having a dominant wavelength of 430 to 456 nm, a red phosphor emitting red light and a green phosphor emitting green light,

wherein the red light emitted from the red phosphor has a color coordinate falling within a space defined by four coordinate points (0.6448, 0.4544), (0.8079, 0.2920), (0.6427, 0.2905) and (0.4794, 0.4633) based on the CIE 1931 chromaticity diagram, and

the green light emitted from the green phosphor has a color coordinate falling within a space defined by four coordinate points (0.1270, 0.8037), (0.4117, 0.5861), (0.4197, 0.5316) and (0.2555, 0.5030) based on the CIE 1931 chromaticity diagram.

8. The display device of claim 7, the backlight unit further comprising a diffusing sheet, wherein the central light amount is measured at the diffusing sheet.

9. The display device of claim 7, wherein the display panel is a liquid crystal panel.

10. The display device of claim 7 further comprising a driving circuit which drives the backlight unit.

11. A television comprising the display device of claim 7.

12. 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 diode modules each comprising a conductive board having at least one first connector and a plurality of second connectors formed thereon, and a plurality of white light emitting diode chips mounted on the conductive board, wherein

the white light emitting diode chips are arranged at a predetermined distance from one another, and

the white light emitting diodes are arranged such that a light emitting diode unit defined by each of the white light emitting diodes and a corresponding one of the white light emitting diodes disposed at a closest distance from the each white light emitting diode has a central light amount ranging from 80% to 120% with respect to an average light amount of the white light emitting diodes.

13. The display device of claim 12, the backlight unit further comprising a diffusing sheet, wherein the central light amount is measured at the diffusing sheet.

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

15. The display device of claim 12 further comprising a driving circuit which drives the backlight unit.

16. A television comprising the display device of claim 12.