Backlight unit
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.
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.