Partitioning member, planar light source, and liquid crystal display device

1. A planar light source comprising:

a substrate;

a plurality of light sources arranged on the substrate; and

at least one partitioning member disposed on the substrate and defining a plurality of partitioned regions arranged in a first direction and in a second direction that intersects the first direction, at least one of the light sources being arranged in a corresponding one of the partitioned regions, the at least one partitioning member including

a plurality of first wall parts defining a plurality of first ridges extending in the first direction, the first wall parts defining at least one first cut on at least one of the first ridges, the at least one first cut extending through an entire thickness of a corresponding one of the first wall parts, and

a plurality of second wall parts defining a plurality of second ridges extending in the second direction,

at least one of the partitioned regions being surrounded by the first ridges and the second ridges in a plan view and including an opposing pair of the first wall parts and an opposing pair of the second wall parts, wherein the at least one first cut segmentalizes the at least one of the first ridges to allow the at least one of the first ridges to shrink along the first direction when a thermal load is applied to the at least one partitioning member.

2. The planar light source according to claim 1 , wherein

the second wall parts define at least one second cut on at least one of the second ridges.

3. The planar light source according to claim 2 , wherein

the at least one first cut and the at least one second cut are continuous with each other to define a continuous cut.

4. The planar light source according to claim 3 , wherein

the continuous cut has a cross-shape in the plan view.

5. The planar light source according to claim 3 , wherein

the continuous cut is positioned at one of intersections between the first ridges and the second ridges, and spaced apart from the intersections that are adjacent to the one of the intersections.

6. The planar light source according to claim 3 , wherein

the first wall parts define a plurality of first cuts including the at least one first cut,

the second wall parts define a plurality of second cuts including the at least one second cut, and

each of all intersections between the first ridges and the second ridges is provided with a corresponding one of the continuous cuts.

7. The planar light source according to claim 3 , further comprising

a lower member disposed under the partitioning member, the lower member including

a plurality of fourth wall parts positioned under the first wall parts, and defining a plurality of fourth ridges extending in the first direction, and

a plurality of fifth wall parts positioned under the second wall parts, and defining a plurality of fifth ridges extending in the second direction, wherein

the lower member defines a lower continuous cut in which a first lower cut on at least one of the fifth ridges and a second lower cut on at least one of the fourth ridges are continuous in the plan view, and

the lower continuous cut is provided at a position not overlapping the continuous cut in the partitioning member in the plan view.

8. The planar light source according to claim 2 , wherein

the first wall parts define a plurality of first cuts including the at least one first cut,

the second wall parts define a plurality of second cuts including the at least one second cut,

each of the first cuts is continuous with a corresponding one of the second cuts to define a plurality of continuous cuts, and

an intersection between one of the first ridges and one of the second ridges is interposed between adjacent ones of the continuous cuts aligned in the first direction.

9. The planar light source according to claim 8 , wherein

an intersection between one of the first ridges and one of the second ridges is interposed between adjacent ones of the continuous cuts aligned in the second direction.

10. The planar light source according to claim 2 , wherein

the at least one first cut and the at least one second cut are spaced apart from each other.

11. The planar light source according to claim 10 , wherein

the first wall parts define a plurality of first cuts including the at least one first cut,

the second wall parts define a plurality of second cuts including the at least one second cut, and

the first cuts and the second cuts are alternately positioned at intersections between the first ridges and the second ridges along the first direction.

12. The planar light source according to claim 11 , wherein

the first cuts and the second cuts are alternately positioned at the intersections along the second direction.

13. The planar light source according to claim 11 , further comprising

a lower member disposed under the partitioning member, the lower member including

a plurality of fourth wall parts positioned under the first wall parts, and defining a plurality of fourth ridges extending in the first direction, the fourth wall parts defining at least one second lower cut on at least one of the fourth ridges at a position intersecting one of the first cuts in the plan view, and

a plurality of fifth wall parts positioned under the second wall parts, and defining a plurality of fifth ridges extending in the second direction, the fifth wall parts defining at least one first lower cut on at least one of the fifth ridges at a position intersecting one of the second cuts in the plan view.

14. The planar light source according to claim 2 , wherein

the first wall parts each has a first lateral wall and a second lateral wall interposing the first ridge, and

the first lateral wall and the second lateral wall are at least partially in contact with each other while the first cut is interposed between the first lateral wall and the second lateral wall.

15. The planar light source according to claim 14 , wherein

the second wall parts each has a third lateral wall and a fourth lateral wall interposing the second ridge, and

the third lateral wall and the fourth lateral wall are at least partially in contact with each other while the second cut is interposed between the third lateral wall and the fourth lateral wall.

16. The planar light source according to claim 1 , wherein

the at least one partitioning member further includes

a plurality of third wall parts defining a plurality of third ridges extending in a third direction different from the first direction and the second direction, and

the partitioned regions being hexagonal partitioned regions arranged in a honeycomb pattern in the plan view with each of the hexagonal partitioned regions being defined by linking the first ridges, the second ridges, and the third ridges.

17. A liquid crystal display device comprising:

a back light source having the planar light source according to claim 16 .

18. A liquid crystal display device comprising:

a back light source having the planar light source according to claim 1 .

19. A partitioning member comprising:

a plurality of first wall parts defining a plurality of first ridges extending in a first direction, the first wall parts defining at least one first cut on at least one of the first ridges, the at least one first cut extending through an entire thickness of a corresponding one of the first wall parts; and

a plurality of second wall parts defining a plurality of second ridges extending in a second direction that intersects the first direction, wherein

the first wall parts and the second wall parts define a plurality of partitioned regions arranged in the first direction and the second direction, each of the partitioned regions being surrounded by the first ridges and the second ridges in a plan view and including an opposing pair of the first wall parts and an opposing pair of the second wall parts, wherein the at least one first cut segmentalizes the at least one of the first ridges to allow the at least one of the first ridges to shrink along the first direction when a thermal load is applied to the partitioning member.

20. The partitioning member according to claim 19 , wherein

the second wall parts define at least one second cut on at least one of the second ridges.