An edge light type backlight unit having an improved light-reception portion. The backlight unit includes one or more light sources that emit light, a light guide panel that guides the propagation of light incident on one side edge thereof, one or more light-reception portions having a first entrance face slanted opposite the side edge of the light guide panel on which the light is incident at a predetermined angle, and one or more reflecting elements that are disposed between each of the light-reception portions and each of the light sources and guides the light emitted by the light source so that it is incident on the first entrance face.
1. A backlight unit comprising:
one or more light sources that emit light;
a light guide panel that guides the propagation of light incident on one side edge thereof;
one or more light-reception portions having a first entrance face slanted opposite the side edge of the light guide panel on which the light is incident at a predetermined angle; and
one or more reflecting elements that are disposed between each of the light-reception portion and each of the light sources and guides the light emitted by the light source so that it is incident on the first entrance face;
wherein each of the one or more reflecting element comprises:
a second entrance face on which the light emitted by the light source is incident;
a reflection face that reflects the light incident through the second entrance face so as to change the propagation path of the light, and
an exit face that directs the light incident directly from the second entrance face and the light incident through the reflection face toward the light-reception portion.
2. The backlight unit of claim 1 , wherein the reflection face comprises:
top and bottom faces disposed opposite and spaced apart from each other by a predetermined distance;
a first rear face that has one side contacting the second entrance face and is disposed parallel to the exit face; and
a second rear face that has one side contacting the first rear face and is slanted opposite the exit face at a predetermined angle.
3. The backlight unit of claim 2 , wherein where an included angle between the second rear face and the exit face is θ 1 , the included angle θ 1 is in a range defined by a conditional expression 10°≦θ 1 ≦30°.
4. The backlight unit of claim 3 , wherein the included angle θ 1 is about 18°.
5. The backlight unit of claim 1 , wherein the reflection face comprises:
top and bottom faces disposed opposite and spaced apart from each other by a predetermined distance; and
a rear face that has one side contacting the second entrance face and is slanted opposite the exit face at an angle, wherein the rear face has a planar structure.
6. The backlight unit of claim 5 , wherein where an included angle between the rear face and the exit face is θ 2 , the included angle θ 2 is in a range defined by a conditional expression 10°≦θ 2 ≦30°.
7. The backlight unit of claim 1 , wherein the reflection face comprises:
top and bottom faces disposed opposite and spaced apart from each other by a predetermined distance; and
a rear face that is aspherically curved and has one side contacting the second entrance face and the other side contacting the exit face.
8. The backlight unit of claim 1 , wherein each of the light-reception portion further comprises a reflection guide face having one side contacting the side edge of the light guide panel and the other side contacting the first entrance face.
9. The backlight unit of claim 8 , wherein where θ 3 is an included angle between the reflection guide face and a normal perpendicular to the side edge of the light guide panel opposite the light-reception portion, the included angle θ 3 is in a range defined by a conditional expression 5°≦θ 3 ≦20°.
10. The backlight unit of claim 9 , wherein the included angle θ 3 is about 13°.
11. The backlight unit of claim 8 , wherein each of the light-reception portion is integrally formed with the light guide panel.
12. The backlight unit of claim 1 , wherein where θ 4 is an included angle between the side edge of the light guide panel and the first entrance face, the included angle θ 4 is in a range defined by a conditional expression 10°≦θ 4 ≦50°.
13. The backlight unit of claim 12 , wherein the included angle θ 4 is about 33°.