Backlight unit

Patent metadata

Field	Value
Publication number	US-9482899-B2
Application number	US-201414473959-A
Country	US
Kind code	B2
Filing date	Aug 29, 2014
Priority date	Feb 18, 2014
Publication date	Nov 1, 2016
Grant date	Nov 1, 2016

Abstract

Provided is a backlight unit including a printed circuit board, a light-emitting diode package, a diffusion plate, and a reflection sheet. The light-emitting diode package including a light-emitting part configured to generate a first light. The diffusion plate includes a first diffusion pattern provided on a first region corresponding to the light-emitting diode package and a second diffusion pattern provided on a second region to have a transmittance higher than that of the first diffusion pattern. The reflection sheet includes an absorption pigment configured to absorb a fraction of the first light with a specific wavelength and converting the first light to a second light, and the reflection sheet is configured to reflect the second light toward the first diffusion pattern. The backlight unit can have improved color coordinate uniformity.

First claim

What is claimed is:

1. A backlight unit, comprising:
a printed circuit board;
a light-emitting diode package provided on and electrically connected to the printed circuit board, the light-emitting diode package including a light-emitting part configured to generate a first light;
a diffusion plate provided on the light-emitting diode package to include first and second diffusion patterns provided on first and second regions, respectively, wherein the second diffusion pattern has a transmittance higher than that of the first diffusion pattern, the first region is provided at a region corresponding to the light-emitting diode package, and the second region is provided to enclose the first region; and
a reflection sheet including a body part and an absorption pigment, wherein the body part is provided at a region corresponding to the first region and is interposed between the printed circuit board and the light-emitting diode package, the absorption pigment is provided on the body part and is configured to absorb a fraction of the first light with a specific wavelength and convert the first light to a second light, and the reflection sheet is configured to reflect the second light toward the first diffusion pattern.

2. The backlight unit of claim 1 , wherein the reflection sheet is provided on a top surface of the printed circuit board.

3. The backlight unit of claim 2 , wherein the first diffusion pattern comprises a plurality of diffusion protrusions that are provided to have a first density, and
the second diffusion pattern comprises a plurality of diffusion protrusions that are provided to have a second density lower than the first density.

4. The backlight unit of claim 2 , wherein the plurality of diffusion protrusions are formed of a material, whose transmittance is higher for a long wavelength fraction of a visible light than for a short wavelength fraction of the visible light.

5. The backlight unit of claim 4 , wherein the absorption pigment is foamed of a material absorbing the long wavelength fraction of the first light more than the short wavelength fraction of the first light.

6. The backlight unit of claim 2 , wherein the absorption pigment is locally provided on a region of the printed circuit board corresponding to the first region.

7. The backlight unit of claim 6 , wherein the reflection sheet has a content of the absorption pigment ranging from 0.01 wt % to 1 wt %.

8. The backlight unit of claim 6 , wherein the reflection sheet further comprises a pigment region shaped like a dot pattern, and
the absorption pigment is disposed on a region of the reflection sheet corresponding to the pigment region.

9. The backlight unit of claim 1 , wherein the printed circuit board is shaped like a bar extending along a specific direction, and
the light-emitting diode package comprises a plurality of light-emitting diode packages arranged in a row along the specific direction of the printed circuit board.

10. The backlight unit of claim 1 , wherein the printed circuit board comprises a connection socket, and
the reflection sheet comprises a terminal hole extending to the connection socket,
wherein the light-emitting diode package comprises a connection terminal electrically connected to the connection socket via the terminal hole.

11. The backlight unit of claim 1 , wherein the light-emitting diode package comprises a lens part covering the light-emitting part, and
a top surface of the lens part is curved to have an upward convex profile, thereby configured to guide the first light toward a side surface thereof,
wherein a slope of a tangent line to the top surface of the lens part decreases from a center thereof to a side surface thereof.

12. The backlight unit of claim 1 , further comprising a reflection plate configured to reflect the first light toward the second diffusion pattern.

13. The backlight unit of claim 12 , further comprising a bottom chassis,
wherein the reflection plate comprises a reflection part configured to reflect the first light toward the second diffusion pattern and an opening extending to a bottom portion of the bottom chassis, and
the printed circuit board is disposed on the bottom portion to which the opening extends.

14. The backlight unit of claim 1 , wherein the light-emitting diode package comprises a lens part covering the light-emitting part, and
a top surface of the light-emitting diode package is curved to have an upward convex profile, thereby configured to guide the first light toward a side surface thereof,
wherein a slope of a tangent line to the top surface of the light-emitting diode package decreases from a center thereof to a side surface thereof.

15. A backlight unit, comprising:
a printed circuit board;
a light-emitting diode package provided on and electrically connected to the printed circuit board, the light-emitting diode package including a light-emitting part configured to generate a first light;
a diffusion plate provided on the light-emitting diode package to include first and second diffusion patterns provided on first and second regions, respectively, wherein the second diffusion pattern has a transmittance higher than that of the first diffusion pattern, the first region is provided at a region corresponding to the light-emitting diode package, and the second region is provided to enclose the first region; and
a reflection plate provided in the second region, the reflection plate including an absorption pigment configured to absorb a fraction of the first light with a specific wavelength and converting the first light to a second light, and the reflection plate is configured to reflect the second light toward the second diffusion pattern.

16. The backlight unit of claim 15 , wherein the first diffusion pattern comprises a plurality of diffusion protrusions that are provided to have a first density, and
the second diffusion pattern comprises a plurality of diffusion protrusions that are provided to have a second density lower than the first density.

17. The backlight unit of claim 16 , wherein the plurality of diffusion protrusions are formed of a material, whose transmittance is higher for a long wavelength fraction of a visible light than for a short wavelength fraction of the visible light.

18. The backlight unit of claim 17 , wherein the absorption pigment is formed of a material absorbing the short wavelength fraction of the first light more than the long wavelength fraction of the first light.

19. The backlight unit of claim 15 , wherein the printed circuit board is shaped like a bar extending along a specific direction, and
the light-emitting diode package comprises a plurality of light-emitting diode packages arranged in a row along the specific direction of the printed circuit board.

20. The backlight unit of claim 15 , wherein the reflection plate further comprises a pigment region that is positioned in the second region and is shaped like a dot pattern, and
the absorption pigment is disposed on a region of the reflection plate corresponding to the pigment region.

Assignees

• Samsung Display Co Ltd

Inventors

• Lee Kang-Woo
• Kim Joonghyun
• Shim Sung-Kyu
• Hwang Seong-Yong
• Kim Dawoon

Classifications

• G02F1/133609 Primary

  including means for improving the color mixing, e.g. white · CPC title

• G02F2001/133607

  Physics · mapped topic

• G02F1/133603 Primary

  with LEDs · CPC title

• G02F1/133606

  including a specially adapted diffusing, scattering or light controlling members · CPC title

• G02F1/133607

  the light controlling member including light directing or refracting elements, e.g. prisms or lenses · CPC title