Lighting device and display device using the lighting device

1. A lighting device comprising a light source;

a light conducting plate having an incident surface receiving light emitted from the light source, a back surface and a light-emitting surface; and

a reflection member having a first portion facing the back surface, and a second portion located on a side opposite a side of the light conducting plate on which the light source is located,

the light conducting plate comprising a plurality of concave portions which include grooves and are formed on the back surface and orient light emitted from the light conducting plate via the back surface toward an emission surface of the lighting device

wherein a parameter related to the plurality of concave portions is weighted so that an even luminance distribution can be obtained on the emission surface, and

the plurality of concave portions are arranged with a first pitch in a center portion of the back surface, and are arranged with a second pitch in an end portion of the back surface.

2. The lighting device as claimed in claim 1 , wherein the plurality of concave portions are arranged with the second pitch in the end portion of the back surface located on both sides of the center portion.

3. A lighting device comprising:

a light source;

a light conducting elate having an incident surface receiving light emitted from the light source, a back surface and a light-emitting surface; and

a reflection member having a first portion facing the back surface, and a second portion located on a side opposite a side of the light conducting plate on which the light source is located,

wherein:

the light conducting plate comprises a plurality of concave portions which include grooves and are formed on the back surface and orient light emitted from the light conducting plate via the back surface toward an emission surface of the lighting device;

a parameter related to the plurality of concave portions is weighted so that an even luminance distribution can be obtained on the emission surface,

the light-emitting surface of the light conducting plate comprises a first inclined surface which goes down from a side of the light conducting plate facing the light source, and a second inclined surface which continues to the first inclined surface and goes down; and

an inclined angle of the second inclined surface is greater than that of the first inclined surface.

4. The lighting device as claimed in claim 3 , wherein the plurality of concave portions are arranged with an identical pitch.

5. The lighting device as claimed in claim 3 , wherein the plurality of concave portions are arranged with different pitches.

6. The lighting device as claimed in claim 3 , wherein the plurality of concave portions are arranged with a first pitch in a center portion of the back surface, and are arranged with a second pitch in an end portion of the back surface.

7. The lighting device as claimed in claim 6 , wherein the plurality of concave portions are arranged with the second pitch in the end portion of the back surface located on both sides of the center portion.