Direct-type backlight unit having surface light source

• US 20080007939A1
• Filed: 07/05/2007
• Published: 01/10/2008
• Est. Priority Date: 07/10/2006
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electro-Mechanics Co., Ltd. (Samsung Group)
• Inventors: Lee, Won Joon, Park, Young Sam, Ahn, Ho Sik, Yeo, In Tae, Song, Chang Ho, Hahm, Hun Joo, Han, Kyung Taeg
• Granted Patent: US 7,887,225 B2
• Time in Patent Office: Days
• US Class Current: 362/97
• CPC Class Codes: G02F 1/133603 with LEDs
• CPC Class Codes: H01L 2224/0401 Bonding areas specifically adapted for bump connectors, e.g. under bump metallisation [UBM]
• CPC Class Codes: H01L 2224/16225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2924/00011 Not 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 2933/005 relating to encapsulations
• CPC Class Codes: H01L 33/52 Encapsulations

Abstract

In a direct-type backlight unit, a board has upper and lower surfaces defining a thickness therebetween. A plurality of unit light sources are disposed on the board. Here, in each of the unit light sources, a wiring pattern is formed on the board. A light emitting device is disposed on the wiring pattern to electrically connect thereto. A non-conductive side wall surrounds, without interruption, the light emitting device at a predetermined interval therefrom, the non-conductive side wall having a height lower than that of the light emitting device. Also, an encapsulant is formed in a dome shape inside the side wall. In this fashion, the light emitting devices are mounted on the board by a chip-on-board technique.

Claims

1. A direct-type backlight unit comprising:

a board having upper and lower surfaces defining a thickness therebetween; and

a plurality of unit light sources mounted on the board, wherein each of the unit light sources comprises;

a wiring pattern formed on the board; and

a light emitting device disposed on the wiring pattern to electrically connect thereto;

a non-conductive side wall surrounding, without interruption, the light emitting device at a predetermined interval therefrom, the non-conductive side wall having a height lower than that of the light emitting device; and

an encapsulant formed in a dome shape inside the side wall.

2. The direct-type backlight unit according to claim 1, wherein the wiring pattern in each of the unit light sources comprises:

upper terminals formed on the upper surface of the board where the light emitting device is disposed to be electrically connected to the light emitting device; and

lower terminals formed on the lower surface of the board; and

internal connectors extending through the board to connect the upper and lower terminals together.

3. The direct-type backlight unit according to claim 1, wherein the light emitting device is electrically connected to the wiring pattern by wire bonding.

4. The direct-type backlight unit according to claim 1, wherein the light emitting device is electrically connected to the wiring pattern by flip chip bonding.

5. The direct-type backlight unit according to claim 1, wherein each of the light sources comprises:

an opaque layer or a light diffusing layer formed on an upper end portion of the encapsulant.

6. The direct-type backlight unit according to claim 1, wherein the side wall comprises a plurality of coating layers.

7. The direct-type backlight unit according to claim 1, wherein the side wall has a width that is 1.5% to 3% of a diameter of the encapsulant.

8. The direct-type backlight unit according to claim 1, wherein the side wall has a height that is 1% to 1.5% of a diameter of the encapsulant.

9. The direct-type backlight unit according to claim 1, wherein the side wall has an outer wall surface inclined toward an inner wall surface in such a way that the side wall has a width decreasing toward an apex.

10. The direct-type backlight unit according to claim 1, wherein the encapsulant has a height that is 25% to 35% of a diameter thereof.

11. The direct-type backlight unit according to claim 10, wherein the encapsulant has a height that is ⅓

of a diameter thereof.

12. The direct-type backlight unit according to claim 1, wherein each of the unit light sources comprises at least two of the light emitting devices mounted inside the side wall.

13. The direct-type backlight unit according to claim 1, wherein the encapsulant comprises a transparent resin or a phosphor-mixed transparent resin.

14. The direct-type backlight unit according to claim 1, wherein some of the encapsulants in the light sources comprise a transparent resin and the other encapsulants comprise a phosphor-mixed transparent resin,

wherein the encapsulants comprising the transparent resin and the encapsulants comprising the phosphor-mixed transparent resin are mixed together.