Backlight unit and display device having backlight unit

• US 9,933,657 B2
• Filed: 11/07/2016
• Issued: 04/03/2018
• Est. Priority Date: 10/31/2014
• Status: Active Grant

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Oh, Sewon, Kim, Eunseok
• Primary Examiner(s): DZIERZYNSKI, EVAN P
• Application Number:
  US15/345,202
• Publication Number:
  US 20170052410A1
• Time in Patent Office: 512 Days
• 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 1/133608 including particular frames or supporting means
• CPC Class Codes: G02F 1/133611 including means for improving the brightness uniformity

Abstract

A backlight unit including a frame including a bottom and a sidewall extending from the bottom; at least one substrate located on the frame, and a plurality of light sources mounted on the at least one substrate; and a reflecting sheet located on the at least one substrate. The reflecting sheet comprises a first sheet part located on the bottom, the first sheet part including a plurality of holes corresponding to the plurality of the light sources; and a second sheet part extended from the first sheet part, the second sheet part including a horizontal dot area located along a long side of the reflecting sheet and a vertical dot area located along a short side of the reflecting sheet, and at least one of the horizontal dot area and the vertical dot area comprising first areas and second areas. In addition, the first areas correspond to outermost holes among the plurality of holes, and the second areas are located between the first areas, the first areas and the second areas include a plurality of dot areas, each of the dot areas includes a plurality of dots, a density of dots included in one of the plurality of dot areas is different from a density of dots included in another of the plurality of dot areas in the first area, a density of dots included in one of the plurality of dot areas is different from a density of dots included in another of the plurality of dot areas in the second area, the first and second areas comprise first dot areas, the first dot areas are positioned at the same distance between a first distance and a second distance from a line, the line being an imaginary line connecting the outermost holes along at least one of the long side and the short side of the reflecting sheet, and a density of dots included in the first dot area of the first area is different from a density of dots included in the first dot area of the second area.

Claims

1. A backlight unit comprising:

a frame including a bottom and a sidewall extending from the bottom;

at least one substrate located on the frame, and a plurality of light sources mounted on the at least one substrate; and

a reflecting sheet located on the at least one substrate,

wherein the reflecting sheet comprises;

a first sheet part located on the bottom, the first sheet part including a plurality of holes corresponding to the plurality of the light sources; and

a second sheet part extended from the first sheet part, the second sheet part including a horizontal dot area located along a long side of the reflecting sheet and a vertical dot area located along a short side of the reflecting sheet, and at least one of the horizontal dot area and the vertical dot area comprising first areas and second areas,

wherein the first areas correspond to outermost holes among the plurality of holes, and the second areas are located between the first areas,

wherein the first areas and the second areas include a plurality of dot areas,

wherein each of the dot areas includes a plurality of dots,

wherein a density of dots included in one of the plurality of dot areas is different from a density of dots included in another of the plurality of dot areas in the first area,

wherein a density of dots included in one of the plurality of dot areas is different from a density of dots included in another of the plurality of dot areas in the second area,

wherein the first and second areas comprise first dot areas, the first dot areas are positioned at the same distance between a first distance and a second distance from a line, the line being an imaginary line connecting the outermost holes along at least one of the long side and the short side of the reflecting sheet, and

wherein a density of dots included in the first dot area of the first area is different from a density of dots included in the first dot area of the second area.

2. The backlight unit of claim 1, wherein the first areas further comprise a protrusion area being closer to the line than the first dot areas.

3. The backlight unit of claim 1, wherein the first and second areas comprise second dot areas positioned between the second distance and a third distance from the line, and

wherein a density of dots included in the second dot area of the first area is different from a density of dots included in the second dot area of the second area.

4. The backlight unit of claim 1, wherein at least one dot closest to the line in the first areas is closer to the line than at least one dot closest to the line in the second areas.

5. The backlight unit of claim 1, wherein the first and second areas comprise second dot areas positioned between the second distance and a third distance from the line, and

wherein the density of dots included in the first dot area of the first area is different from a density of dots included in the second dot area of the first area.

6. The backlight unit of claim 1, wherein the first and second areas comprise second dot areas positioned between the second distance and a third distance from the line, and

wherein the density of dots included in the first dot area of the second area is different from a density of dots included in the second dot area of the second area.

7. The backlight unit of claim 1, wherein the line includes a first line along the long side of the reflecting sheet and a second line along the short side of the reflecting sheet, and

wherein a distance between the first line and a closest dot to the first line on the horizontal dot area is greater than a distance between the second line and a closest dot to the second line on the vertical dot area.

8. The backlight unit of claim 1, wherein dot patterns of the horizontal dot area are different from dot patterns of the vertical dot area.

9. The backlight unit of claim 1, wherein an area of the horizontal dot area is different from an area of the vertical dot area.

10. The backlight unit of claim 1, wherein, in a corner of the reflecting sheet, a shape of the horizontal dot area is asymmetric with a shape of the vertical dot area.

11. The backlight unit of claim 1, wherein the line includes a first line along the long side of the reflecting sheet and a second line along the short side of the reflecting sheet, and

wherein a distance between the first line and a farmost dot in a vertical direction from the first line on the horizontal dot area is different from a distance between the second line and a farmost dot in a horizontal direction from the second line on the vertical dot area.

12. The backlight unit of claim 1, wherein the reflecting sheet further comprises a third sheet part extending from the second sheet part and being located on the sidewall.

13. The backlight unit of claim 12, wherein, in the second sheet part, the density of dots of the first areas and the second areas increases as the dots approach the third sheet part.

14. The backlight unit of claim 12, wherein the first areas further include a third dot area,

wherein the third dot area is closer to the third sheet part than the first dot area, and

wherein a density of dots included in the third dot area is greater than the density of dots included in the first dot area.

15. The backlight unit of claim 14, wherein the density of dots included in the second dot area is greater than the density of dots included in the first dot area.

16. The backlight unit of claim 12, wherein the third sheet part comprises a long third sheet part along the long side of the reflecting sheet and a short third sheet part along the short side of the reflecting sheet,

wherein the line includes a first line along the long side of the reflecting sheet and a second line along the short side of the reflecting sheet, and

wherein a distance between the first line and the long third sheet part is different from a distance between the second line and the short third sheet part.

17. The backlight unit of claim 1, wherein the second sheet part is bent from the first sheet part.

18. The backlight unit of claim 1, wherein the first area and the second area are sequentially positioned.

19. A display device comprising:

a display panel;

a backlight unit at a rear of the display panel; and

a back cover at a rear of the backlight unit,

wherein the backlight unit comprises;

a frame including a bottom and a sidewall extending from the bottom;

at least one substrate located on the frame, and a plurality of light sources mounted on the at least one substrate; and

a reflecting sheet located on the at least one substrate,

wherein the reflecting sheet comprises;

a first sheet part located on the bottom, the first sheet part including a plurality of holes corresponding to the plurality of the light sources; and

a second sheet part extended from the first sheet part, the second sheet part including a horizontal dot area located along a long side of the reflecting sheet and a vertical dot area located along a short side of the reflecting sheet, and at least one of the horizontal dot area and the vertical dot area comprising first areas and second areas,

wherein the first areas correspond to outermost holes among the plurality of holes, and the second areas are located between the first areas,

wherein the first areas and the second areas include a plurality of dot areas,

wherein each of the dot areas includes a plurality of dots,

wherein a density of dots included in one of the plurality of dot areas is different from a density of dots included in another of the plurality of dot areas in the first area,

wherein a density of dots included in one of the plurality of dot areas is different from a density of dots included in another of the plurality of dot areas in the second area,

wherein the first and second areas comprise first dot areas, the first dot areas are positioned at the same distance between a first distance and a second distance from a line, the line being an imaginary line connecting the outermost holes along at least one of the long side and the short side of the reflecting sheet, and

wherein a density of dots included in the first dot area of the first area is different from a density of dots included in the first dot area of the second area.

20. The display device of claim 19, wherein the first areas further comprise a protrusion area being closer to the line than the first dot areas.

21. The display device of claim 19, wherein the first and second areas comprise second dot areas positioned between the second distance and a third distance from the line, and

wherein a density of dots included in the second dot area of the first area is different from a density of dots included in the second dot area of the second area.

22. The display device of claim 19, wherein at least one dot closest to the line in the first areas are closer to the line than at least one dot closest to the line in the second areas.

23. The display device of claim 19, wherein the first and second areas comprise second dot areas positioned between the second distance and a third distance from the line, and

wherein a density of dots included in the first dot area of the first area is different from a density of dots included in the second dot area of the first area.

24. The display device of claim 19, wherein the first and second areas comprise second dot areas positioned between the second distance and a third distance from the line, and

wherein a density of dots included in the first dot area of the second area is different from a density of dots included in the second dot area of the second area.

25. The display device of claim 19, wherein the line includes a first line along the long side of the reflecting sheet and a second line along the short side of the reflecting sheet, and

wherein a distance between the first line and a closest dot to the first line on the horizontal dot area is greater than a distance between the second line and a closest dot to the second line on the vertical dot area.

26. The display device of claim 19, wherein dot patterns of the horizontal dot area are different from dot patterns of the vertical dot area.

27. The display device of claim 19, wherein an area of the horizontal dot area is different from an area of the vertical dot area.

28. The display device of claim 19, wherein, in a corner of the reflecting sheet, a shape of the horizontal dot area is asymmetric with a shape of the vertical dot area.

29. The display device of claim 19, wherein the line includes a first line along the long side of the reflecting sheet and a second line along the short side of the reflecting sheet, and

wherein a distance between the first line and a farmost dot in a vertical direction from the first line on the horizontal dot area is different from a distance between the second line and a farmost dot in a horizontal direction from the second line on the vertical dot area.

30. The display device of claim 19, wherein the reflecting sheet further comprises a third sheet part extending from the second sheet part and being located on the sidewall.

31. The display device of claim 30, wherein, in the second sheet part, the density of dots of the first areas and the second areas increases as the dots approach the third sheet part.

32. The display device of claim 30, wherein the first areas further include a third dot area,

wherein the third dot area is closer to the third sheet part rather than the first dot area, and

wherein a density of dots included in the third dot area is greater than the density of dots included in the first dot area.

33. The display device of claim 32, wherein the density of dots included in the second dot area is greater than the density of dots included in the first dot area.

34. The display device of claim 30, wherein the third sheet part comprises a long third sheet part along the long side of the reflecting sheet and a short third sheet part along the short side of the reflecting sheet,

wherein the line includes a first line along the long side of the reflecting sheet and a second line along the short side of the reflecting sheet, and

wherein a distance between the first line and the long third sheet part is different from a distance between the second line and the short third sheet part.

35. The display device of claim 19, wherein the second sheet part is bent from the first sheet part.

36. The display device of claim 19, wherein the first area and the second area are sequentially positioned.