Backlight unit for LCD using LED

• US 8,148,897 B2
• Filed: 04/26/2006
• Issued: 04/03/2012
• Est. Priority Date: 04/27/2005
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electro-Mechanics Co., Ltd. (Samsung Group)
• Inventors: Cho, Jae-hee, Kim, Hyung-kun, Sone, Cheol-soo
• Primary Examiner(s): Ton, Toan
• Assistant Examiner(s): Hanley, Britt D
• Application Number:
  US11/411,094
• Publication Number:
  US 20060244712A1
• Time in Patent Office: 2,169 Days
• Field of Search: None
• US Class Current: 313/512
• CPC Class Codes: G02B 6/0023 provided by one optical element, or plurality thereof, placed between the light guide and the light source, or around the light source
• CPC Class Codes: G02B 6/0068 Arrangements of plural sources, e.g. multi-colour light sources
• 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: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336
• CPC Class Codes: G09G 3/3413 Details of control of colour illumination sources

Abstract

A backlight unit for a liquid crystal display (LCD) using a light emitting diode (LED) is provided. The backlight unit includes a blue light source, a red light source, and a green light source. The green light source includes an ultraviolet (UV) LED and a green phosphor excited by light emitted from the UV LED.

Claims

1. A backlight unit using LED (light emitting diode), the backlight unit comprising a blue light source, a red light source, and a green light source,

wherein the green light source comprises a first UV (ultraviolet) LED, the blue light source comprises a second UV LED, and the red light source comprises a third UV LED,

wherein at least one of the green, blue and red light source comprises:

a packaging frame having a cup-shaped recess recessed downwardly from a surface of the packaging frame;

a silicone sub-mount disposed on a bottom of the recess of the package frame;

at least one of the a first, second and third UV LEDs is mounted on the silicone sub-mount;

a silicone resin is formed on an upper surface of the silicone sub-mount by surface tension to bulgingly surround all surfaces exposed by the silicone sub-mount of the at least one of the first, second and third UV LEDs on the upper surface of the silicone sub-mount, wherein the silicone resin is not directly disposed on the packaging frame; and

at least one of a green, blue and red phosphor which is excited by light emitted from at least one of the first, second and third UV LEDs,

wherein an upper surface of the silicone sub-mount defines a silicone resin forming region.

2. The backlight unit of claim 1, wherein the blue light source, the red light source, and the green light source are used in the same ratio, and current supplied to the blue light source, the red light source, and the green light source are the same as each other.

3. The backlight unit of claim 1, wherein the green phosphor is formed by adding an activator to one material selected from the group consisting of ZnS, (BaSr)₂SiO₄, LaPO₄, and BaMgAl₁₀O₁₇.

4. The backlight unit of claim 1, wherein a peak wavelength of the first UV LED is 430 nm or less.

5. The backlight unit of claim 4, wherein the first UV LED includes an InGaAIN active layer.

6. The backlight unit of claim 1, wherein the silicone resin surrounding the first UV LED is formed between the first UV LED and the green phosphor, and the green phosphor is formed on the silicone resin.

7. The backlight unit of claim 1, wherein the green phosphor is mixed with the silicone resin to bulgingly surround the first UV LED on the silicone sub-mount.

8. The backlight unit of claim 1, wherein the blue light source comprises:

a packaging frame having a cup-shaped recess recessed downwardly from a surface of the packaging frame;

a silicone sub-mount disposed on a bottom of the recess of the package frame;

the second UV LED mounted on the silicone sub-mount;

a silicone resin formed on an upper surface of the silicone sub-mount by surface tension, to bulgingly surround the second UV LED on the upper surface of the silicone sub-mount; and

a blue phosphor excited by light emitted from the second UV LED.

9. The backlight unit of claim 8, wherein the blue phosphor is formed by adding an activator to Ca₂(PO₄)₆C₁₂ and/or Sr₅(PO₄)₃Cl.

10. The backlight unit of claim 8, wherein the silicone resin surrounding the second UV LED is formed between the second UV LED and the blue phosphor, and the blue phosphor is formed on the silicone resin.

11. The backlight unit of claim 8, wherein the blue phosphor is mixed with the silicone resin to bulgingly surround the second UV LED on the silicone sub-mount.

12. The backlight unit of claim 1, wherein the red light source comprises:

a packaging frame having a cup-shaped recess recessed downwardly from a surface of the packaging frame;

a silicone sub-mount disposed on a bottom of the recess of the package frame;

the third UV LED mounted on the silicone sub-mount;

a silicone resin formed on an upper surface of the silicone sub-mount by surface tension, to bulgingly surround the third UV LED on the upper surface of the silicone sub-mount; and

a red phosphor excited by light emitted from the third UV LED.

13. The backlight unit of claim 12, wherein the red phosphor is formed by adding an activator to one material selected from the group consisting of SrS, Y₂O₂S, YVO, M(WO), and M is a material selected from the group consisting of Li, Na, K, Ba, Ca, and Mg.

14. The backlight unit of claim 12, wherein the silicone resin surrounding the third UV LED is formed between the third UV LED and the red phosphor, and the red phosphor is formed on the silicone resin.

15. The backlight unit of claim 12, wherein the red phosphor is mixed with the silicone resin to bulgingly surround the third UV LED on the silicone sub-mount.