JPH0428144Y2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field The present invention relates to a surface light source device used for back illumination of liquid crystal cells, etc.

Prior Art A lighting device using a surface light source device needs to be made as thin as possible as a whole. Conventionally, the surface light source device itself requires multiple light sources when its area becomes large, and it is necessary to increase the distance between the light source and the device in order to increase the irradiation area. For example, in a relatively large-area device such as a liquid crystal television, the above-mentioned demand for compactness of the surface light source device has been met by combining a plurality of surface light sources in units of relatively small area.

However, in such a structure made up of a combination of unit units, the amount of light decreases at the connection between the units, and this connection causes uneven light emission for the surface light source as a whole.

Purpose In view of the above-mentioned circumstances, the present invention aims to make the device more compact by combining surface light sources in units of multiple units, and to provide a surface light source device that does not cause uneven light emission even at the connection between the units. It is.

Summary According to the present invention, the above object is to provide a refraction section having a lens effect near the connecting portion between the surface light source units, so that the light from the light source is also incident on the area corresponding to the connecting portion. This is achieved by

Embodiment The present invention will be described in detail based on the illustrated embodiment. In FIG. 1, reference numeral 1 is arranged on the back side of the liquid crystal cell l, and the back surface 2a is provided with protrusions having a sawtooth cross section. A surface light source unit consisting of a transparent plate 2 formed as a rough surface and a light source (not shown), in which the protrusion on the back surface 2a is perpendicular to the optical axis of the light source which is inclined at a predetermined angle with the surface of the surface light source unit. It has a surface and a surface opposite thereto, on which a reflective film made of a silver or aluminum film is formed, either by being formed on the polished surface or by plating or the like. Reference numeral 3 denotes a refraction plate which is disposed close to the surface light source unit 1 on the liquid crystal cell l side and has refraction portions 3a and 3b near the ends of the surface light source unit 1.

Since the surface light source device of the present invention is configured as described above, the light from the light source that is incident on the area other than the peripheral area of the surface light source unit 1 is directed to the surface perpendicular to the optical axis of the protrusion on the back surface 2a. It is reflected by the surface opposite to the orthogonal surface, enters the refracting plate 3 perpendicularly, passes straight through the refracting plate 3, and then reaches the back surface of the liquid crystal cell l. Further, the light incident on the end of the surface light source unit 1 is once refracted toward the cutout portion 4 between the adjacent transparent plates 2 and 2 in the refraction plate 3a due to the lens effect of the refraction plate 3, and then further refracted by the refraction plate 3a. 3
When passing through b, the light is refracted in a direction perpendicular to the surface of the surface light source unit 1. Therefore, even if there is a missing part of the surface light source behind the liquid crystal cell l, light is allowed to enter the corresponding part, so that uneven illumination of the liquid crystal cell l is prevented at the connection part of the surface light source unit 1. Uniform illumination is provided without any glare. For example, the interval x of the deleted portion 4 is 1 to 3
Even in the case of about mm, if the relationship d>x is satisfied between the distance x and the width d of the refracting plate 3, the back surface of the liquid crystal cell l corresponding to the missing portion 4 of the surface light source will also be covered. It can be irradiated evenly. Even when a plurality of surface light source units 1 are combined in this way, uneven light emission does not occur at the connecting portions, so that it is more effective for back illumination of the liquid crystal cell I.

FIG. 2 shows another embodiment, in which reference numeral 2b is a refraction section provided at the end of the transparent plate 2 almost symmetrically with the refraction section 3a. Therefore, the light from the light source reflected by the protrusions on the back surface 2a is reflected by the refracting portion 2b.
The light is further refracted toward the cutout portion 4 side, and further refracted in a direction perpendicular to the surface of the surface light source unit 1 when passing through the refraction portions 3a and 3b of the refraction plate 3. In this case, the light from the light source also enters the corresponding part of the liquid crystal cell l which has the cutout part 4 of the surface light source behind it by the refracting parts 2b, 3a, and 3b, so that the back is uniform as a whole and has no uneven light emission. Lighting is provided.

In the above embodiment, the bending parts 2b and 3a, 3
The dimensions, shapes, etc. of each of the elements b are selected appropriately for actual use, and the number of combined surface light source units 1 is also selected appropriately depending on the size of the liquid crystal cell l, etc. Further, the transparent plate 2 and the refracting plate 3 may be formed separately, or may be formed integrally.

Effects of the Invention As described above, the surface light source device of the present invention can provide uniform illumination without causing uneven light emission at each connected portion even when a plurality of surface light source units are combined. When used, there are advantages such as making the device more compact and realizing effective back lighting.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing one embodiment of a surface light source device according to the present invention, particularly showing a connecting portion between surface light source units, and FIG. 2 is a similar cross-sectional view showing another embodiment. 1... Surface light source unit, 2... Transparent plate, 3...
Refraction plate, 2b, 3a, 3b...Refraction portion, 4...Deletion portion, l...Liquid crystal cell.

Claims (1)

[Scope of utility model registration request] A plurality of flat surface light source units are identically configured so that the light source light incident from the side is emitted from the front surface as parallel light on the back surface, which is formed as a rough surface formed by arranging protrusions with serrated cross-sections in parallel. In a surface light source device arranged in parallel on a plane with a predetermined gap, refracting plates having a predetermined thickness that commonly cover the surface side of each surface light source unit are arranged adjacent to each other, and the thickness of the refracting plate is adjusted. In addition, a light refraction section having a lens effect is formed in a portion facing the gap, and the illumination light is transmitted to a portion corresponding to the gap via the light refraction section. A surface light source device characterized in that a surface light source device is made to exist.