JPS6355503A - Luminaire - Google Patents

Abstract

PURPOSE:To improve the efficiency and the luminance by reflecting a part of the light from a light source, which goes to a first reflective face, on the first reflective face and reflecting another part of this light, which goes to a second reflective face, on the second reflective face and the first reflective face and outputting both parts of the light in a prescribed direction as rays parallel with an output optical axis. CONSTITUTION:A luminaire is provided with the first reflective face 2a, which is arranged on the opposite side of the light output direction, and the second reflective face 2b which is arranged on the light output side correspondingly to the first reflective face 2a. The second reflective face 2b is a plane shape vertical to the output optical axis of the luminaire and permits the light incident at a small angle of incidence to pass through and has such property that the light L2 which is made incident on the second reflective face 2b at a large angle of incidence from the light source arranged between the first and second reflective faces 2a and 2b is reflected toward the first reflective face 2a, and the first reflective face 2a has such property that the light L1 which is made directly incident on the first reflective face from the light source and the light L2 which is reflected on the second reflective face 2b and is made incident on the first reflective face 2a are reflected on the first reflective face 2a in a direction parallel or approximately parallel with the output optical axis.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a lighting device with a light guide suitable for, for example, a liquid crystal display pack, a light, and the like.

Prior Art Display devices include those that emit light by themselves, such as light-emitting diodes and electroluminescent displays, and those that do not emit light themselves, such as liquid crystal displays, that control the transmittance or reflectance of light. Some devices display patterns by modulating natural light or light emitted from other illumination sources. Liquid crystal displays utilize their optical anisotropy, and in the case of polarizing plates or color display devices, the light 1 is further reduced by a color filter, so it is not necessary to add lighting means for general indoor use. This is an essential requirement.

4 and 5 show examples of conventional lighting devices used for this purpose, in which 11 is a light source, 12 and 1
3 is a light guide body for reflection, and 14 is a diffuser plate.

The light guide main body 12.13 is for reflecting the light beam from the light source 11 and outputting it upward in the figure, and directs most of the light beam upward to equalize the brightness over the entire surface of the diffuser plate 14. In this case, it is desirable that the reflective surface has a parabolic shape and that the light source 11 is located at the focal point of the reflective surface. However, since there is a limit to the thickness of the illumination device, it is actually forced to have a flat shape. As shown in the tlS4 diagram, a plurality of band-shaped reflective surfaces 15 are arranged so as to have a flat shape as a whole, and the angle of each reflective surface 15 is set so that the light ray from the light source 11 is a light ray L0 parallel to the output optical axis. A 7-lens lens-shaped object set at an angle that allows reflection upward is often used, 16 is a non-reflective surface provided between each reflective surface 15, 17
is a diffuser plate for brightness adjustment.

<Problems to be solved by the invention> Even in the case of the structure shown in Fig. 4, the light 1i11
The light rays La and Lb are emitted directly toward the diffuser plate 14 from
Even if Ln is diffused by the diffuser plate 14, the component in the direction parallel to the output optical axis decreases as it goes outward, and the luminance of the upper surface of the diffuser plate 14 seen from the direction of the output optical axis decreases. The degree of contribution gradually decreases toward the outside. For this reason,
With conventional lighting devices equipped with light guides, it has been difficult to achieve high efficiency and high brightness.

The present invention has been made in view of these problems, and aims to provide a lighting device that is simple in construction and provides high brightness.

Means for Solving the Problems> In order to achieve the above-mentioned object, the lighting device of the present invention includes a first reflective surface disposed on the side opposite to the direction in which light is output; a second reflective surface disposed on the output side corresponding to the reflective surface; It has the property of transmitting light rays incident at an angle of incidence, and reflecting light rays incident at a large angle of incidence from a light source disposed between the first and second reflecting surfaces toward the reflecting surface of ml, A light ray that directly enters the first reflective surface from a light source and a light ray that is reflected by the second reflective surface and enters the first reflective surface,
It has the property of reflecting in a direction parallel or almost parallel to the output optical axis.

<Operation> According to the present invention, among the light rays emitted from the light source, those directed toward the first reflective surface are directly reflected by the first reflective surface,
The light directed toward the reflective surface of tJ2 is reflected by the second reflective surface and the first reflective surface, and both are output as light rays in a direction parallel or almost parallel to the output optical axis. The amount of light rays transmitted is significantly reduced, resulting in a highly efficient lighting device.

<Example> Next, the illustrated embodiment will be explained.

FIG. 1 is a sectional view of the first embodiment, in which 1 is a light source, 2 is a light guide body, and 3 is a diffuser plate.

The light source 1 has a tubular shape that is long in the direction perpendicular to the plane of the paper, and has a groove 4 with a U-shaped cross section recessed in the surface of the light guide body 2.
It is stored inside. The guide main body 2 is made of a translucent material and has a first reflective surface 2a on the rear side of the light source 1 and a second reflective surface 2b on the front side. The first reflective surface 2a has a 7-Renel lens shape in which a plurality of band-shaped reflective surfaces 5 are arranged alternately with non-reflective surfaces 6 so as to have a flat overall shape, and the first reflective surface 2a has a 7-Renel lens shape. A reflective layer 7 is coated to increase reflectance. The angle of each strip-shaped reflective surface 5 is such that the light 11L incident on each reflective surface from the light source 1 is converted into a light ray L0 parallel to the output optical axis.
It is set at an angle that allows it to be reflected upward. The second reflective surface 2b is a mirror plane perpendicular to the output optical axis of the illumination device, and the light rays incident at a small incident angle are transmitted as they are, but the light #aL2 incident at a large incident angle is designed to undergo total internal reflection. For example, in the case of acrylic resin, the angle at which total reflection occurs is approximately 42° or more.

Therefore, the light ray L2 emitted from the light rA1 is reflected by the reflective surface 2b of ff12, becomes a light ray L2°, and is reflected by the first reflective surface 2a.
, is reflected by the band-shaped reflective surface 5, becomes a light beam L3, passes through the diffuser plate 3, and is output. In this case, tjs
A mirror image of light source 1 exists in O2 with the reflecting surface 2b of light source 2 as the axis of symmetry, and the direction of the light ray is determined by the optical IQ.
Although it is slightly different from t-O, it becomes parallel to the output optical axis, and it becomes possible to effectively use the light from the light source 1 as illumination light.

Also, in this example? A protruding reflective surface 8 is formed in an inverted V shape at a portion of the reflective surface 2a of the lSl directly below the light source 1.

This reflects the light rays emitted directly downward from the light source 1 on this protruding reflective surface 8, and further on the second reflective surface 2b and the first reflective surface 8.
The light II L is reflected by the band-shaped reflective surface 5 of the reflective surface 2a of
, which is emitted almost parallel to the output optical axis,
This is effective in effectively utilizing the light rays emitted from the light source 1 and further increasing the efficiency of irradiation. Note that this protruding reflecting surface 8 may have any shape as long as it reflects the light beam from the light source 1 in the left-right direction, and may be, for example, arc-shaped.In addition, in the structure of this embodiment, the light if! Since the brightness directly above the light 'a1 is particularly high, a brightness adjusting diffuser plate 9 is provided above the light 'a1. Note that if fW4 is shallow -1, the light source 1 will protrude from the groove 4, which will cause the amount of light transmitted through the light guide body 2 to decrease and the brightness to decrease.
It is thicker than the diameter of the

In the case of the above-mentioned embodiment, since the light source 1 is surrounded by resin, heat dissipation is poor, and there is a possibility that the temperature of the resin near the light source will rise and a part of the light guide body 2 may be deformed after long-term use. This also makes it difficult to replace the light source 1. Second
The figure shows a second embodiment that takes this point into consideration, in which a groove 4a having a U-shaped cross section is formed in the back surface of the light guide main body 2, and the light source 1 is housed in this groove 48. Projected reflective surface 8
The other configuration is basically the same as the first embodiment except that the light source 1 is not provided, and in this conventional example, since the area directly below the light source 1 is open, it is difficult to replace the light source 1. and
It also has good heat dissipation and can prevent heat generation.

Furthermore, since the light beam emitted directly downward from the light source 1 is not utilized, the efficiency may decrease slightly, but this may be due to the fact that, for example, due to coating or pasting, the
This can be improved by forming a reflective layer on the lower surface of A1.

tjs3 figure is another example,
A round hole 4b is provided in the hole 4b, into which the light source 1 is inserted. This embodiment also has the same IQ as the first embodiment. f
Although there is a f1 point, there is no practical problem if the amount of heat generated by the light source 1 is small.

Further, in this embodiment, the thickness of the brightness adjustment diffuser plate 9a is increased at the center. This is to thicken the attenuation of light at the center and obtain a surface light source with uniform brightness.

Also, light! ! If the diameter of the brightness adjusting diffuser plate 4& is about 4-1, the width of the brightness adjusting diffuser plate 4& may be about 6 mm, and this also applies to the first and second embodiments.

In each of the above embodiments, the light source 1 is long in the shape of a tube in the direction perpendicular to the plane of the paper, and the figure is a cross-sectional view thereof, but the present invention can also be applied to the case of a point-like light source. . That is, in this case, the light guide main body 2 has a disk shape with one point light source 1 at the center, and each band-shaped reflective surface 5 of the reflective surface 2a has an annular shape, but the light source part has a circular shape. The cross-sectional views are the same as those in FIG. 1 to Pt53.

<Effects of the Invention> As is clear from the above-described embodiments, in the present invention, among the light rays emitted from the light source, those directed toward the first reflective surface are directly reflected by the first reflective surface, and the light rays emitted from the light source are directly reflected by the second reflective surface. The light that is directed towards is reflected by the second reflecting surface and the first reflecting surface, and ultimately both rays are output in a predetermined direction as rays parallel or almost parallel to the output optical axis. It is something.

Therefore, the amount of light rays that deviate from the output optical axis and go in unnecessary directions is greatly reduced, resulting in a surface light source with high efficiency and high brightness. An illumination device suitable for use as a backlight of a display device that requires an illumination means can be easily obtained.

[Brief explanation of drawings]

Figure 2 is a sectional view of an embodiment of fjSl of this invention,
The figure is a cross-sectional view of an example of Pt52, FIG. 3 is a cross-sectional view of the third example, and FIG. 4 and the tjSS diagram are cross-sectional views of a conventional example. 1...Light source, 2...Light guide body 2
a...first reflective surface, 26...second reflective surface 5.
... Band-shaped reflective surface, 6... Non-reflective surface 1 Figure 2! ll1 114! ! 1! 15W

Claims (1)

[Claims] 1. It includes a first reflective surface disposed on the opposite side to the light output direction, and a second reflective surface disposed on the light output side corresponding to the first reflective surface, The second reflective surface has a planar shape perpendicular to the output optical axis of the illumination device, transmits light rays incident at a small angle of incidence, and is disposed between the first and second reflective surfaces. It has the property of reflecting the light rays incident from the light source at a large incident angle towards the first reflecting surface, and the first reflecting surface is used to reflect the light rays directly entering from the light source and the light rays reflected by the second reflecting surface. 1. A lighting device having a property of reflecting an incident light beam in a direction parallel or substantially parallel to an output optical axis.