Backlight unit and liquid crystal display device including the same

• US 11,029,562 B2
• Filed: 10/19/2018
• Issued: 06/08/2021
• Est. Priority Date: 10/31/2017
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Display Co., Ltd.
• Inventors: Lee, Rok-Hee, Kwak, Yong-Seok, Kim, Il-Soo
• Primary Examiner(s): Caley, Michael H
• Assistant Examiner(s): Jung, Jonathan Y
• Application Number:
  US16/165,779
• Publication Number:
  US 20190129249A1
• Time in Patent Office: 963 Days
• CPC Class Codes: G02B 5/021 the diffusion taking place at the element's surface, e.g. by means of surface roughening or microprismatic structures
• CPC Class Codes: G02F 1/133504 Diffusing, scattering, diffracting elements associated to illuminating devices G02F1/133606
• CPC Class Codes: G02F 1/133603 with LEDs
• CPC Class Codes: G02F 1/133605 including specially adapted reflectors
• CPC Class Codes: G02F 1/133606 including a specially adapted diffusing, scattering or light controlling members
• CPC Class Codes: G02F 1/133607 the light controlling member including light directing or refracting elements, e.g. prisms or lenses
• CPC Class Codes: G02F 1/133611 including means for improving the brightness uniformity
• CPC Class Codes: G02F 1/133614 using photoluminescence, e.g. phosphors illuminated by UV or blue light
• CPC Class Codes: G09G 2310/08 Details of timing specific for flat panels, other than clock recovery
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336
• CPC Class Codes: G09G 3/342 using several illumination sources separately controlled corresponding to different display panel areas, e.g. along one dimension such as lines
• CPC Class Codes: G09G 3/36 using liquid crystals

Abstract

A liquid crystal display device comprises a liquid crystal panel and a backlight unit under the liquid crystal panel and including a circuit board; a plurality of LED packages mounted on the circuit board; an encapsulation member over the circuit board and covering the plurality of LED packages; and a multi-pattern sheet over the encapsulation member and including a glass complex body containing a phosphor and a plurality of diffusion patterns on an upper surface of the glass complex body, wherein the plurality of diffusion patterns include at least one first pattern corresponding to an LED package and at least one second pattern corresponding to a portion between adjacent LED packages.

Claims

1. A backlight unit, comprising:

a circuit board;

a plurality of LED packages mounted on the circuit board;

an encapsulation member over the circuit board and covering the plurality of LED packages; and

a multi-pattern sheet over the encapsulation member and including

a glass complex body containing a phosphor, and

a plurality of diffusion patterns on an upper surface of the glass complex body,

wherein the plurality of diffusion patterns includes a plurality of first patterns, each of the first patterns aligned with a respective LED package of the plurality of LED packages along a first direction, and a plurality of second patterns, each of the second patterns aligned with a respective portion between adjacent LED packages of the plurality of LED packages along the first direction and alternating the each of the first patterns such that a single second pattern is disposed between adjacent first patterns of the plurality of first patterns,

wherein the first patterns and the second patterns are different patterns,

wherein the single second pattern is a single horn having a vertex, and the single horn is disposed between the adjacent first patterns, and

wherein a width of a bottom surface of the single horn contacting the upper surface of the glass complex body is smaller than a width of a bottom surface of each of the adjacent first patterns contacting the upper surface of the glass complex body.

2. The backlight unit of claim 1, wherein the first patterns include a curved surface without a vertex, and the second patterns include a triangle-like shape with a vertex.

3. The backlight unit of claim 2, wherein the first patterns include a hemispherical shape, and the second patterns include a conical shape, a polypyramid shape, or a conical shape having a curved side surface.

4. The backlight unit of claim 1, wherein the diffusion patterns include at least one of an embossed pattern or a depressed pattern.

5. The backlight unit of claim 1, wherein the multi-pattern sheet further includes a plurality of reflective patterns on a lower surface of the glass complex body, and the plurality of reflective patterns correspond to the plurality of LED packages, respectively.

6. The backlight unit of claim 5, wherein one or more of the plurality of reflective patterns have a transmittance at an edge portion that is higher than a transmittance at a center portion.

7. The backlight unit of claim 6, wherein the one or more of the plurality of reflective patterns includes first, second, and third pattern layers sequentially stacked, and an area of the second pattern layer is smaller than an area of the first pattern layer and greater than an area of the third pattern layer.

8. The backlight unit of claim 5, wherein a width d of each reflective pattern satisfies a following equation,

d=2{(b−

c)tan(θ

/2)},

wherein b is a height of the encapsulation member, c is a height of each LED package, and θ

is a beam angle of light emitted by the LED package.

9. The backlight unit of claim 1, wherein each LED package includes an LED chip and a reflection member over the LED chip, and the reflection member comprises two successively stacked layers having different refractive indexes.

19. The backlight unit of claim 1, wherein each LED package overlaps with a center of a first pattern and is spaced apart from a center of a second pattern adjacent to the center of the first pattern.

24. The backlight unit of claim 1, wherein a maximum thickness of the encapsulation member is five times a thickness of each of the plurality of LED packages.

10. A backlight unit, comprising:

a circuit board;

a plurality of LED packages mounted on the circuit board;

an encapsulation member over the circuit board and covering the plurality of LED packages; and

a multi-pattern sheet over the encapsulation member and including

a glass complex body containing a phosphor,

a plurality of diffusion patterns on an upper surface of the glass complex body, and

a plurality of reflective patterns on a lower surface of the glass complex body,

wherein the plurality of diffusion patterns includes a plurality of first patterns, each of the first patterns aligned with a respective LED package of the plurality of LED packages along a first direction, and a plurality of second patterns, each of the second patterns aligned with a respective portion between adjacent LED packages of the plurality of LED packages along the first direction and alternating the each of the first patterns such that a single second pattern is disposed between adjacent first patterns of the plurality of first patterns,

wherein at least one of the LED packages, at least one of the reflective patterns, and at least one of the first patterns overlap each other,

wherein the first patterns and the second patterns are different patterns,

wherein the single second pattern is a single horn having a vertex, and the single horn is disposed between the adjacent first patterns, and

wherein a width of a bottom surface of the single horn contacting the upper surface of the glass complex body is smaller than a width of a bottom surface of each of the adjacent first patterns contacting the upper surface of the glass complex body.

20. The backlight unit of claim 10, wherein the at least one of the LED packages overlaps with a center of the at least one of the first patterns and is spaced apart from a center of a second pattern adjacent to the center of the at least one of the first patterns.

11. A liquid crystal display device, comprising:

a liquid crystal panel; and

a backlight unit under the liquid crystal panel and including;

a circuit board;

a plurality of LED packages mounted on the circuit board;

an encapsulation member over the circuit board and covering the plurality of LED packages; and

a multi-pattern sheet over the encapsulation member and including

a glass complex body containing a phosphor, and

a plurality of diffusion patterns on an upper surface of the glass complex body,

wherein the plurality of diffusion patterns includes a plurality of first patterns, each of the first patterns aligned with a respective LED package of the plurality of LED packages along a first direction, and a plurality of second patterns, each of the second patterns aligned with a respective portion between adjacent LED packages of the plurality of LED packages along the first direction and alternating the each of the first patterns such that a single second pattern is disposed between adjacent first patterns of the plurality of first patterns, each of the plurality of first patterns being spaced from each single pattern of the plurality of second patterns,

wherein the first patterns and the second patterns are different patterns,

wherein the single second pattern is a single horn having a vertex, and the single horn is disposed between the adjacent first patterns, and

wherein a width of a bottom surface of the single horn contacting the upper surface of the glass complex body is smaller than a width of a bottom surface of each of the adjacent first patterns contacting the upper surface of the glass complex body.

12. The liquid crystal display device of claim 11, wherein the first patterns include a curved surface without a vertex, and the second patterns include a triangle-like shape with a vertex.

13. The liquid crystal display device of claim 12, wherein the first patterns include a hemispherical shape, and the second patterns include a conical shape, a polypyramid shape, or a conical shape having a curved side surface.

14. The liquid crystal display device of claim 11, wherein the multi-pattern sheet further includes a plurality of reflective patterns on a lower surface of the glass complex body, and the plurality of reflective patterns correspond to the plurality of LED packages, respectively.

15. The liquid crystal display device of claim 14, wherein one or more of the plurality of reflective patterns have a transmittance at an edge portion that is higher than a transmittance at a center portion.

16. The liquid crystal display device of claim 15, wherein the one or more of the plurality of reflective patterns includes first, second, and third pattern layers sequentially stacked, and an area of the second pattern layer is smaller than an area of the first pattern layer and greater than an area of the third pattern layer.

17. The liquid crystal display device of claim 14, wherein a width d of each reflective pattern satisfies a following equation,

d=2{(b−

c)tan(θ

/2)},

wherein b is a height of the encapsulation member, c is a height of each LED package, and θ

is a beam angle of light emitted by the LED package.

18. The liquid crystal display device of claim 11, wherein each LED package includes an LED chip and a reflection member over the LED chip, and the reflection member comprises two successively stacked layers having different refractive indexes.

21. The liquid crystal display device of claim 11, wherein each LED package overlaps with a center of a first pattern and is spaced apart from a center of a second pattern adjacent to the center of the first pattern.

22. The liquid crystal display device of claim 11, wherein each of the first patterns is overlapped with the respective LED package of the plurality of LED packages.

23. A backlight unit, comprising:

a circuit board;

a plurality of LED packages mounted on the circuit board;

an encapsulation member over the circuit board and covering the plurality of LED packages; and

a multi-pattern sheet over the encapsulation member and including

a glass complex body containing a phosphor, and

a plurality of diffusion patterns on an upper surface of the glass complex body,

wherein the plurality of diffusion patterns includes a plurality of first patterns, two first patterns aligned with a respective LED package of the plurality of LED packages along a first direction, and a plurality of second patterns, two second patterns aligned with a respective portion between adjacent LED packages of the plurality of LED packages along the first direction and alternating the two first patterns,

wherein the two first patterns have a same size, and the two second patterns have a same size,

wherein the first patterns and the second patterns are different patterns, and

wherein a width of a bottom surface of each of the two second patterns contacting the upper surface of the glass complex body is smaller than a width of a bottom surface of each of the two first patterns contacting the upper surface of the glass complex body.