Backlight unit and liquid crystal display having the same

1. A backlight unit comprising:

a light-guide plate guiding incident light and having a diffusion pattern for emitting light upward, the diffusion pattern being formed on at least one of upper and lower surfaces of the light-guide plate; and

a point light source assembly disposed on at least one side portion of the light-guide plate, the point light source assembly comprising a plurality of point-light-source elements and a support substrate, in which the point-light-source elements are disposed on the support substrate and supply the light to the light-guide plate,

wherein an edge portion of one surface of the light-guide plate, which is adjacent to the point light source assembly, comprises a first region corresponding to the point-light-source elements and a second region corresponding to a position between the point-light-source elements, and

the diffusion pattern is not formed on the edge portion,

wherein a width of the edge portion of said one surface of the light-guide plate, in which the diffusion pattern is not formed, is equal to or greater than an interval between adjacent point-light-source elements, and

wherein a direction of the width is perpendicular to a direction of the interval.

2. The backlight unit of claim 1 , further comprising a reflection film for dark regions disposed between the point-light-source elements, the reflection film for dark regions reflecting the light emitted from a side portion of the light-guide plate back to the light-guide plate.

3. The backlight unit of claim 2 , wherein the reflection film for dark regions is formed on a side portion of the light-guide plate corresponding to the position between the point-light-source elements.

4. The backlight unit of claim 2 , wherein the reflection film for dark regions is formed on the support substrate corresponding to the position between the point-light-source elements.

5. The backlight unit of claim 2 , wherein the width of the edge portion of the surface of the light-guide plate, in which the diffusion pattern is not formed, is within the range of about 4 to 6 mm, and the interval between point-light-source elements is within the range of about 4 to 5 mm.

6. A backlight unit comprising:

a light-guide plate guiding incident light and having a diffusion pattern for emitting light upward, wherein the diffusion pattern is formed on at least one of upper and lower surfaces of the light-guide plate and the light-guide plate comprises an edge portion which is adjacent to a point light source assembly and is formed along at least one side of the light-guide plate, and an inner portion which is a remaining portion of the light-guide plate; and

the point light source assembly disposed on at least one side portion of the light-guide plate, the point light source assembly comprising a plurality of point-light-source elements and a support substrate, in which the point-light-source elements are disposed on the support substrate and supply the light to the light-guide plate,

wherein the diffusion pattern is formed on one surface of the light-guide plate, except for the edge portion of said one surface of the light-guide plate, and

wherein a width of the edge portion of said one surface of the light-guide plate, in which the diffusion pattern is not formed, is equal to or greater than an interval between adjacent point-light-source elements, and

wherein a direction of the width is perpendicular to a direction of the interval.

7. The backlight unit of claim 6 , wherein the width of the edge portion of the one surface of the light-guide plate, in which the diffusion pattern is not formed, is within a range of about 4 to 6 mm.

8. The backlight unit of claim 6 , wherein the interval between point-light-source elements is within a range of about 4 to 5 mm.

9. The backlight unit of claim 6 , further comprising a reflection film for dark regions disposed between the point-light-source elements, the reflection film for dark regions reflecting the light emitted from a side portion of the light-guide plate back to the light-guide plate.

10. The backlight unit of claim 9 , wherein the reflection film for dark regions is formed on one side portion of the light-guide plate corresponding to a position between the point-light-source elements.

11. The backlight unit of claim 9 , wherein the reflection film for dark regions is formed on the support substrate corresponding to a position between the point-light-source elements.

12. A backlight unit comprising:

a light-guide plate guiding incident light and having a diffusion pattern for emitting light upward, wherein the diffusion pattern is formed on at least one of upper and lower surfaces of the light-guide plate;

a point light source assembly disposed on at least one side portion of the light-guide plate, the point light source assembly comprising a plurality of point-light-source elements and a support substrate, in which the point-light-source elements are disposed on the support substrate and supply the light to the light-guide plate; and

a reflection film for dark regions is formed on a side surface of the light-guide plate corresponding to a position between the point-light-source elements, the reflection film for dark regions reflecting the light emitted from a side portion of the light-guide plate back to the light-guide plate,

wherein the reflection film is uncurved and a width of the reflection film is less than a interval of between adjacent point-light-source elements.

13. The backlight unit of claim 12 , wherein an edge portion of one surface of the light-guide plate, which is adjacent to the point light source assembly, comprises a first region corresponding to the point-light-source elements and a second region corresponding to a position between the point-light-source elements;

the diffusion pattern is formed in such a manner that the second region has a higher density than the first region; and

the diffusion pattern is not formed on the first region.

14. The backlight unit of claim 12 , wherein the diffusion pattern is formed on one surface of the light-guide plate, except for a predetermined edge portion of said one surface of the light-guide plate which is adjacent to the point light source assembly; and

a width of the edge portion of the surface of the light-guide plate, in which the diffusion pattern is not formed, is equal to or greater than an interval between the point-light-source elements.

15. The backlight unit of claim 14 , wherein the width of the edge portion of the surface of the light-guide plate, in which the diffusion pattern is not formed, is within a range of about 4 to 6 mm.

16. The backlight unit of claim 14 , wherein the interval between point-light-source elements is within a range of about 4 to 5 mm.