Luminescent diode, fabrication method thereof, and backlight assembly having the same

• US 20070153545A1
• Filed: 06/14/2006
• Published: 07/05/2007
• Est. Priority Date: 12/29/2005
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Display Co., Ltd.
• Inventors: Lee, Jae
• Granted Patent: US 7,407,312 B2
• Time in Patent Office: Days
• US Class Current: 362/610
• CPC Class Codes: G02B 6/0073 Light emitting diode [LED]
• CPC Class Codes: G02B 6/0085 Means for removing heat created by the light source from the package heat extraction or cooling elements for semiconductor light sources in general H01L33/64
• CPC Class Codes: G02F 1/133603 with LEDs
• CPC Class Codes: G02F 1/133611 including means for improving the brightness uniformity
• CPC Class Codes: G02F 1/133615 Edge-illuminating devices, i.e. illuminating from the side
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/49107 on the semiconductor or solid-state body
• CPC Class Codes: H01L 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/181 Encapsulation
• CPC Class Codes: H01L 33/56 Materials, e.g. epoxy or silicone resin
• CPC Class Codes: H01L 33/58 Optical field-shaping elements

Abstract

A luminescent diode (LED) that improves brightness uniformity, a fabrication method thereof, and a backlight assembly having the same are disclosed. The LED includes an LED chip that emits light in a side surface of an LCD device; and an optical guide element on the LED chip that enlarges a radiation angle of the light. The LED may alternatively include an LED chip that emits light on a bottom surface of the LCD device; and an optical guide element on the LED chip that enlarges a radiation angle of the light. The radiation angle of light maximally enlarged to prevent hot spots caused by brightness nonuniformity. An enhanced image quality results.

Claims

1. A luminescent diode (LED) for a liquid crystal display (LCD) device, comprising:

an LED chip that emits light on a side surface of the LCD device; and

an optical guide element on the LED chip that enlarges a radiation angle of the light.

2. The luminescent diode (LED) according to claim 1, wherein the optical guide element includes a plurality of optical fibers.

3. The luminescent diode (LED) according to claim 2, wherein each of the plurality of optical fibers includes one of a glass material and a plastic material.

4. The luminescent diode (LED) according to claim 1, wherein the optical guide element is disposed around the LED chip.

6. The luminescent diode (LED) according to claim 1, wherein the optical guide element is fixed by a first epoxy and a second epoxy.

7. The luminescent diode (LED) according to claim 1, wherein the optical guide element comprises an input end that receives light, an output end that releases light, a core in which light propagates, a cladding layer formed on the core that reflects light, and a coating layer formed on the cladding layer that intensifies the strength of the optical guide element.

8. The luminescent diode (LED) according to claim 7, wherein a length of the optical guide element is about 750 μ

m, and a diameter of the optical guide element is about 250 μ

m.

5. The luminescent diode (LED) according to claim 5, wherein the optical guide element is inclined at a predetermined angle in a range of about 20°

to about 60°

based on a bottom surface.

9. A method of fabricating a luminescent diode (LED), comprising:

mounting an LED chip on a substrate;

electrically connecting the LED chip by wire bonding;

forming a partition wall over edges of the substrate;

molding a first insulating material into an interior surrounded by the partition wall;

fixing an optical guide element in the first insulating material; and

molding a second insulating material on the first insulating material.

10. The method according to claim 9, further including hardening the first insulating material, wherein the optical guide element is fixed before the first insulating material is hardened.

11. The method according to claim 9, wherein the optical guide element is fixed to the first insulating material such that the optical guide element has a predetermined tilt angle.

12. The method according to claim 11, wherein the tilt angle is in a range of about 20°

to about 60°

based on a bottom surface.

13. The method according to claim 9, wherein the first insulating material and the second insulating material are formed of an epoxy.

14. The method according to claim 9, further comprising molding a fluorescent mold in which a predetermined fluorescent material is mixed before molding the first insulating material.

15. A backlight assembly, comprising:

a light source having an optical guide element, wherein the optical guide element enlarges a radiation angle of light; and

an optical sheet that diffuses and condenses light emitted from the light source.

16. The backlight assembly according to claim 15, further comprising a light guide plate substantially coplanar with the light source that converts light generated from the light source into a surface light and that irradiates light towards a liquid crystal display panel.

17. The backlight assembly according to claim 15, wherein the optical guide element includes a plurality of optical fibers.

18. The backlight assembly according to claim 15, wherein the optical guide element has a predetermined tilt angle in a range of about 20°

to about 60°

based on a bottom surface.

19. The backlight assembly according to claim 15, wherein the optical guide element is disposed around an LED chip.

20. The backlight assembly according to claim 15, wherein the light source comprises:

an LED chip that emits light; and

the optical guide element on the LED chip that enlarges a radiation angle of light.

21. A luminescent diode (LED) for a liquid crystal display (LCD) device, comprising:

an LED chip that emits light on a bottom surface of the LCD device; and

an optical guide element on the LED chip that enlarges a radiation angle of the light.