Light emitting diode backlight and liquid crystal display having the same

1. A backlight unit for use in a liquid crystal display, the backlight unit comprising:

a light guiding plate comprising a light exiting surface, a light reflective surface, and a light incident surface;

a light source unit comprising a substrate and a light source disposed on the substrate, wherein the light source unit is disposed to face the light incident surface of the light guiding plate; and

a reflecting sheet comprising a first portion facing the light reflective surface of the light guiding plate, a second portion facing the light exiting surface of the light guiding plate, and a third portion connecting the first and the second portions, wherein the third portion comprises light source exposing parts,

wherein the light source comprises a plurality of light emitting diodes, and each of the light emitting diodes is square shaped, and a portion of each corresponding light source exposing part is shaped in a quadrangular pyramid to receive the corresponding light emitting diode.

2. The backlight unit of claim 1 , wherein the light source exposing parts protrude toward the light incident surface of the light guiding plate.

3. The backlight unit of claim 2 , wherein the light source exposing parts are configured and dimensioned to seal around the circumference of the light emitting diodes.

4. The backlight unit of claim 1 , wherein the light emitting diodes are disposed in the light source exposing parts and an end of each light emitting diode is aligned with an end of each light source exposing part when the light source unit is combined with the reflecting sheet.

5. The backlight unit of claim 1 , wherein at least a part of the light emitting diodes protrudes beyond the light source exposing parts toward the light guiding plate when the light source unit is combined with the reflecting sheet.

6. The backlight unit of claim 1 , wherein the light source exposing parts are formed with holes corresponding to the light emitting diodes, and projections protruding toward the light guiding plate are formed between each pair of light source exposing parts.

7. The backlight unit of claim 6 , wherein the projections protrude beyond the light emitting diodes when the light source unit is combined with the reflecting sheet.

8. The backlight unit of claim 1 , wherein the reflecting sheet is formed using a mold.

9. The backlight unit of claim 8 , wherein the reflecting sheet comprises a base having aluminum and a coating part comprising a reflective substance, wherein the coating part is formed on the base.

10. The backlight unit of claim 1 , wherein the light source unit further comprises projections disposed between each pair of light emitting diodes.

11. The backlight unit of claim 10 , wherein the projections are disposed facing the incident surface of the light guiding plate and passing through a plurality of holes formed on the third portion of the light guiding plate.

12. The backlight unit of claim 1 , wherein the substrate of the light source unit extends parallel to the incident surface of the light guiding plate.

13. A liquid crystal display comprising:

a liquid crystal display panel on which an image is formed;

a light guiding plate disposed behind the liquid crystal display panel and comprising a light exiting surface, a light reflective surface, and a light incident surface;

a light source unit comprising a substrate and a light source disposed on the substrate, wherein the light source unit is disposed to face the light incident surface of the light guiding plate and the light source comprises a plurality of light emitting diodes; and

a reflecting sheet comprising a first portion facing the light reflective surface of the light guiding plate and a second portion connected to the first portion,

wherein the second portion comprises light source exposing parts,

wherein each light source exposing part receives a light emitting diode and projects toward the light incident surface.

14. The liquid crystal display of claim 13 , wherein the reflecting sheet further comprises a third portion that is connected to the second portion for covering a part of the light exiting surface of the light guiding plate.

15. The liquid crystal display of claim 13 , wherein each of the light emitting diodes is square shaped, and a portion of each corresponding light source exposing part is shaped in a quadrangular pyramid to receive the corresponding light emitting diode, and wherein each light source exposing part is configured and dimensioned to seal around the circumference of the light emitting diodes.

16. The liquid crystal display of claim 13 , wherein the light emitting diode exposing parts are formed with holes corresponding to the light emitting diodes, and wherein projections protruding toward the light guiding plate are formed between each light source exposing part.

17. The liquid crystal display of claim 13 , wherein the reflective sheet is formed using a mold.

18. A backlight unit for use in a liquid crystal display, the backlight unit comprising:

a reflecting sheet for receiving a light source and a light guiding plate,

wherein the reflecting sheet comprises a first portion for receiving a first surface of the light guiding plate and a second portion connected to the first portion, and wherein the second portion comprises a plurality of holes to receive and expose the light source, wherein the second portion comprises projections each protruded toward a second surface of the light guiding plate.

19. The backlight unit of claim 18 , wherein the reflecting sheet comprises a base and a coating part disposed on the base.

20. The backlight unit of claim 19 , wherein the base comprises aluminum and the coating part comprises silver or titanium.

21. The backlight unit of claim 18 , wherein the projections of the second portion are formed between each pair of the plurality of holes.

22. The backlight unit of claim 18 , wherein the light source comprises a plurality of light emitting diodes.