2 to be located at a position higher than the light emitting surface of the light source 3.

In the embodiment, only the uniaxial linear Fresnel lens 5a extending in the longitudinal direction (X-axis direction) of the substrate 2 is employed in order to condense light only in the lateral direction (Y-axis direction) of the substrate 2. As a result, in the embodiment, the lens misalignment in the long-side direction can be ignored. In the embodiment, in the visual field range adjustment lens 7, the lenticular lenses are provided in both the X-axis direction and the Y-axis direction. However, since the lenticular lenses have the same shape pattern, it is not necessary to take the lens position deviation into account.

When the reflector 4 is grounded to the substrate 2, the wall part 4c of the reflector 4 and the light source 3 are close to each other, and the reflector 4 and the light source 3 may interfere with each other when the reflector 4 and the light source 3 expand and contract. On the other hand, in the embodiment, since the opening 4b of the reflector 4 is disposed at a position higher than the light emitting surface of the light source 3, even if the reflector 4 and the light source 3 expand and contract, there is no possibility of contact between the wall part 4c of the reflector 4 and the light source 3.

Since the interval between the light sources 3 is narrow, when the bottom surface 4d of the reflector 4 is disposed at the substrate 2, the size of the bottom surface 4d cannot be increased, thus it is difficult to increase the height of the wall part 4c of the reflector 4 from the viewpoint of moldability of injection molding. On the other hand, in the embodiment, the size of the opening 4b of the reflector 4 can be made smaller than the outer periphery of the light source 3 as long as the opening 4b is larger than the light emitting surface of the light source 3 in the top view. That is, in the embodiment, the size of the opening 4b can be reduced. In other words, in the embodiment, the size of the bottom surface 4d can be increased, and as a result, the height of the wall part 4c of the reflector 4 formed by injection molding can be increased. For this reason, in the embodiment, it is possible to obtain effects of high contrast at the time of local dimming and removal of unnecessary light distribution.

Modification Example

The planar illumination device 1 described in the above embodiment is merely an example, and various modifications can be made. Hereinafter, modification examples of the planar illumination device 1 will be described.

First Modification Example

The planar illumination device 1 of the first modification example has the same prism structure (the linear Fresnel lens 5a, the linear prism 6a, the first lenticular lens 7a, and the second lenticular lens 7b) as the structure of the embodiment, but the arrangement of each prism structure is different from the arrangement of the embodiment.

FIG. 7 is a view for explaining the first modification example. First, the planar illumination device 1 of the first modification example includes, as a first lens, the condenser lens 5 such that the linear Fresnel lens 5a is provided at the surface opposite to the surface opposing the substrate 2, as a first lens, as in the embodiment. The planar illumination device 1 of the first modification example includes a second lens 60 and a third lens 70.

In the second lens 60, the second lenticular lens 7b is provided at a surface opposing the first lens (the condenser lens 5), and a linear prism 6a extending in the X-axis direction is provided at a surface opposite to the surface opposing the first lens (the condenser lens 5). In the third lens 70, the first lenticular lens 7a is provided at a surface opposing the second lens 60.

In the first modification example, in the Y-axis direction, the light emitted from the light source 3 is condensed at the emission surface of the light distribution lens 5 (first lens) and becomes substantially parallel light, the optical axis is inclined at the emission surface of the second lens 60, and the visual field range is adjusted on the incident surface of the third lens 70. In the first modification example, the luminance distribution of the light emitted from the light source 3 is adjusted by the incident surface of the second lens 60 in the X-axis direction. Even in such a configuration order of the lenses, as in the embodiment, it is possible to realize the required light distribution characteristics while ensuring high luminance.

In the third lens 70, a diffusion surface 80 is formed at a surface opposite to a surface opposing the second lens 60. In the first modification example, since the second lenticular lens 7b is provided at the lens having the linear prism 6a, the diffusion surface 80 having the same function as the diffusion sheet 8 can be formed at the upper surface of the third lens 70, and the number of components can be reduced.

Second Modification Example

The planar illumination device 1 of the second modification example has the same prism structure (the linear Fresnel lens 5a, the linear prism 6a, the first lenticular lens 7a, and the second lenticular lens 7b) as the structure of the embodiment, but the arrangement of each prism structures and the number of lenses are different from those of the embodiment.

FIG. 8 is a view for explaining the second modification example. The planar illumination device 1 of the second modification example includes a first lens 51 and a second lens 61. In the first lens 51, the linear Fresnel lens 5a is provided at a surface opposing the substrate 2, and the linear prism 6a is provided at a surface opposite to the surface opposing the substrate 2. In addition, the second lens 61 is disposed at the emission side of the first lens 51, the second lenticular lens 7b is provided at the surface opposing the first lens, and the first lenticular lens 7a is provided at the surface opposite to the surface opposing the first lens 51.

In the second modification example, in the Y-axis direction, the light emitted from the light source 3 is condensed at the incident surface of the first lens 51 and becomes substantially parallel light, the optical axis is inclined at the emission surface of the first lens 51, and the visual field range is adjusted on the emission surface of the second lens 61. On the other hand, in the second modification example, the luminance distribution of the light emitted from the light source 3 is adjusted by the incident surface of the second lens 61 in the X-axis direction. Even in such a configuration order of the lenses, as in the embodiment, it is possible to realize the required light distribution characteristics while ensuring high luminance.