JPH04331901A - Light illumination module - Google Patents

Abstract

PURPOSE:To effectively improve variance of diffused illumination light due to photoconductors by improving the photoconductor structure of the light illumination module. CONSTITUTION:This module has couples of substrates 1 and photoconductors 13. On the substrates 1, LED elements 2 as light sources are mounted respectively and those substrates are arranged so that the surfaces where the LED elements 2 are mounted face each other. The photoconductors 13 are arranged between said couple of substrates 1 and plural light-transmissivity resin plates 8 formed to gradually different sizes corresponding to the distance directions from the LED elements 2 on the substrates 1 are laminated so that the side end positions on the sides of the LED elements 2 are aligned.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a lighting module using a light emitting element such as an LED (light emitting diode) element as a light source for illuminating a light transmitting display device, and more particularly to a light transmitting module for illuminating a light transmitting display device. The present invention relates to a lighting module suitable for illuminating a device.

0002

[Prior Art] Various display devices using light-transmitting liquid crystal display elements such as transmissive liquid crystal elements are similar to ordinary reflective liquid crystal display devices in environments where the surrounding area is brighter than a certain level. When the surroundings are darker than a certain level, such as at night, the displayed content can be recognized by the illumination light from a light source such as a lighting module installed below or behind the liquid crystal display element. It functions so that it can be recognized.

The lighting module includes a backlight type module in which small LED elements are placed behind the display element as a light source and directly illuminates the display element, and a light guide plate in which the LED element as a light source is placed behind and on the side of the display element. LED with a sidelight type module that uses a sidelight module to guide illumination light behind the display element and illuminate it indirectly, reducing the overall thickness.
2 types and EL (electroluminescence)
Backlight type EL types and the like are known, in which an element is used as a light source and is placed behind a display element to directly illuminate the display element.

[0004] Among the above-mentioned lighting modules, the present invention provides:
Since the present invention is applied to a sidelight type illumination module that uses an LED element as a light source and indirectly illuminates using a light guide plate, this sidelight type illumination module will be described in detail. FIG. 4 shows the structure of a conventional sidelight type lighting module using indirect lighting using a common LED.

[0005] As an LED serving as a light source, an LED element 1 made of a chip-shaped package element is generally used. When the LED element 1 is mounted on the printed wiring board 2, the LED element 1 is attached to the end surface of the light guide plate 3 made of a light-transmitting resin.
The LED element 1 is arranged so that light is introduced from the upper surface thereof. The reason for arranging the light to enter the light guide plate 3 from the upper surface of the LED element 1 is that in normal cases, the LED element 1
This is because it is taken into consideration that the distribution of the amount of light emitted by the element is highest in the direction of the top surface of the package.

[0006] Such lighting modules are often constructed from a collection of individual parts due to the demand for thinning. That is, in the configuration shown in FIG. 4, the printed wiring boards 2 on which the LED elements 1 are mounted are manufactured in pairs, which are coupled to the base printed wiring board 4 through the insertion holes 5, and the pairs are connected to the base printed wiring board 4 through the insertion holes 5. The mutual circuits with the printed wiring board 2 are electrically connected by a connecting means 11 such as soldering. Note that the printed wiring board 2 includes a base printed wiring board 4.
A connecting leg portion is formed corresponding to the insertion hole 5 of. Therefore, the combination of the printed wiring board 2 and the base printed wiring board 4 constitutes a U-shaped angle member for mounting and supporting the light guide plate 3.

FIG. 5 shows the structure of the illumination module of FIG. 4 viewed from the top side, and the shape of the base printed wiring board 4 is not clearly shown because it can take various shapes. FIG. 4 corresponds to a schematic cross-sectional view taken along line AA' in FIG.

The structure of the lighting module is shown in FIG.
In addition to the configuration shown in FIG. 5, the base printed wiring board 4 and the printed wiring board 2 on which the LED element 1 is mounted are connected together with a flexible printed wiring board, and the flexible printed wiring board is bent. In some cases, a U-shaped angle member is constructed by fixing it in a state as shown in FIG.

[0009]

[Problems to be Solved by the Invention] The biggest problem with the configuration of the conventional lighting module as described above is the illumination level as a result of the light from the LED element 1 serving as the light source being guided and diffused by the light guide plate 4. The brightness of the illumination light varies depending on the position on the light guide plate 4. That is, Figure 5
In this case, a large difference in brightness inevitably occurs between the region B of the light guide plate 4 close to the light source and the region C far from the light source.

[0010] In order to avoid such problems, it is necessary to apply fluorescent paint or a bright, light-reflecting coating such as white paint to the back of the light guide plate 4, that is, on the base printed wiring board 4 in the area where the light guide plate 4 is disposed. A method of forming a colored layer 7 by applying a paint with a high color tone, or creating fine scratches on the bottom surface 6 of the light guide plate 4 by hairline treatment etc. to increase the diffusion effect by diffused reflection or forming a diffusion surface. Methods of increasing the diffusion effect through matte processing have been considered or are being used. However, even with these methods, sufficient light guidance and diffusion to region C in FIG. 5 cannot be realized, and although the difference in brightness between region B and region C can be improved to some extent, The uneven brightness still remains.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a lighting module that can improve the light guide structure and effectively improve the variation in diffused illumination caused by the light guide. There is.

0012

[Means for Solving the Problems] A lighting module according to the present invention includes a pair of substrates each having a light emitting element mounted thereon as a light source and arranged with the surfaces on which these light emitting elements are mounted facing each other, and A plurality of light-transmitting resin plates are arranged between the substrates and are formed so that the dimensions of each substrate are gradually different in the distance direction from the light source, and the side edge positions on the light source side are aligned. It is characterized by comprising a light guide formed by laminating layers.

[0013]

[Operation] In the illumination module of the present invention, the light guide has a laminated structure of a plurality of light-transmitting resin plates whose dimensions in the distance direction from the light source are gradually different, without changing the basic structure of the module. Therefore, the light diffusing surface at the end of each light-transmitting resin plate on the side far from the light source can be appropriately distributed in an area far from the light source, and variations in illumination level depending on position can be effectively improved. can.

[0014]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a cross-sectional configuration of a lighting module according to a first embodiment of the present invention, and FIG. 2 shows a configuration of the lighting module according to the same embodiment as viewed from the top. (A cross section taken along line D-D' is shown).

As shown in FIGS. 1 and 2, the illumination module differs from FIGS. 4 and 5 only in that a light guide 13 is provided instead of the light guide plate 3, and the LED element 1 and printed The wiring board 2, base printed wiring board 4, and connection means 11 are the same as those in FIGS. 4 and 5.

The light guide 13 is constructed by laminating a plurality of thin light-transmitting resin plates 8. Each of the plurality of light-transmitting resin plates 8 has a width dimension (dimension in the left-right direction in the drawing) that covers almost the entire distance between the paired LED elements 1, and the other light-transmitting resin plates 8 The width is less than 1/2 of the entire width between the elements 1, and each pair of the elements 1 has the same width, and the width gradually decreases in each pair. These plurality of light-transmitting resin plates 8 are
Pairs of light-transmitting resin plates 8 whose widths gradually decrease are stacked on a light-transmitting resin plate 8 having a width that spans almost the entire distance between the D elements 1, with their ends aligned in the width direction. Therefore, the incident end face 1 of each light-transmitting resin plate 8 where the light is incident
2 are aligned, and the position of the diffusion end surface 9 that diffuses and emits the light of each light-transmissive resin plate 8 gradually approaches the incident end surface 12 from approximately the center as it goes to the upper layer. A recessed portion opening upward in the shape of a substantially V-shaped groove is formed in the center of the body 13.

As shown in the drawing, this light guide 13 has a light transmitting resin plate 8 having a width extending almost entirely between the LED elements 1 on the base printed board 4 side, and each pair of light beams having a width gradually decreasing in width. The transmissive resin plate 8 is mounted between the printed wiring boards 2 with the concave portion formed at the center in the width direction facing a display element such as a liquid crystal.

Although the overall thickness of the light guide 13 is related to the mounting width of the LED element 1,
When a D element is used, it is about 1.5 mm. As mentioned earlier, in this embodiment, the light guide 13 having this thickness is formed by laminating a plurality of transparent light guide resin plates 8, and the distance of each layer from the light source is adjusted as shown in the figure. The dimension in the direction is changed stepwise, the diffusion end face 9 of each layer is arranged on the side far from the light source, and the position of the incident end face 12 on the light source side is aligned. For example, if the overall thickness of the light guide 13 is 1.5 mm, and the thickness of the light-transmitting resin plates 8 of each layer is 0.3 mm, theoretically five light-transmitting resin plates 8 can be used. A light guide 13 can be configured.

The light guide 13 may be manufactured by laminating the light transmitting resin plates 8 of each layer by any suitable method depending on the type of resin material to be used. As the resin material for the light-transmitting resin plate 8, it is preferable to use a material such as polycarbonate, which has good light guiding properties and good diffusion through the end face, and also has heat fusion properties, and when such a material is used, This can be easily achieved by laminating light-transmitting resin plates 8 having sufficient length in the length direction, that is, the direction in which the grooves of the recesses extend, and having different widths, integrating them by thermocompression, and cutting them to the required size. A plurality of light guide bodies 13 can be manufactured.

Furthermore, if the light transmitting resin plate 8 is made thinner and the number of laminated sheets is increased, the incidence of light from the incident end face 12 tends to be obstructed. The 12 side portions may be integrated to encourage light to enter each layer.

By arranging the above-described light guide 13 in the same manner as a conventional light guide plate as shown in FIG. 2, the illumination according to this embodiment is such that the concave portion is located at the position C where the illumination level decreases. In the module, the diffusion end face 9 of each layer of the light-transmitting resin plate 8 diffuses the light guided from the LED element 1 serving as the light source, so that effective illumination can be performed at a position far from the light source of the light guide 13. In this case, the direction in which the recesses of the light guide 13 formed by the diffusion end surfaces 9 of each layer of the light-transmitting resin plate 8 are arranged may be reversed from the illustrated state.
There is no significant difference in the illumination effect whether the light guide 13 is oriented upward or downward.

Furthermore, since the light guide 13 of this embodiment can be easily manufactured as described above, it is advantageous in terms of cost compared to the case where it is integrally molded by injection molding. As described above, according to this first embodiment, the following effects can be obtained. (1) Attenuation of the amount of illumination light at a position away from the light source is improved, and the entire light guide 13 can illuminate the display element almost uniformly. (2) The overall thickness of the light guide 13 can be easily adjusted by changing at least one of the thickness of the light-transmitting resin plates 8 to be laminated and the number of laminated plates. (3) The light guide 13 can be manufactured at a lower cost than manufacturing by integral injection molding.

The present invention is not limited to the embodiments described above and shown in the drawings, but can be implemented with various modifications without changing the gist thereof.

For example, when the light intensity of the light source is large, the diffused light from the diffused end face 9 of each layer of the light-transmitting resin plate 8 constituting the light guide 13 will be seen as a line, which may cause uneven illumination. be. Therefore, in order to alleviate such illumination unevenness, in the lighting module according to the second embodiment of the present invention, as shown in FIG. The concave portion is filled with a resin 10 that is light-transmissive and has a diffusion effect, thereby forming an integrated light guide 14 in a block shape. In this case, as the light-diffusing resin 10 that has light transmittance and has a light-diffusing effect, for example, a transparent epoxy resin in which an appropriate amount of silica powder is dispersed and mixed can be used.

By filling the concave portion with the light diffusing resin 10, it is possible to alleviate the uneven illumination that is visually recognized in a linear manner due to the diffused light on the diffusing end face 9 of each layer of the light-transmitting resin plate 8 constituting the light guide 14. Can be done. Furthermore, by doing so, the entire shape of the light guide 14 can be made into a simple rectangular parallelepiped, so the light guide 14 can be handled in the same way as the conventional light guide plate 3.

In this second embodiment, the effect of alleviating uneven illumination by filling the light diffusing resin 10 into the recessed portion is better when the recessed portion faces the upper surface, that is, the side where the display element such as the liquid crystal is disposed. It is even more effective. Furthermore, the light guide 14 of this embodiment can be easily manufactured as described above, and therefore is advantageous in terms of cost compared to integral molding by injection molding.

According to this second embodiment, the above-mentioned first
In addition to the effects obtained in the embodiment, the light diffusing resin 10 has light transmittance and light diffusing properties in the recesses formed by the diffusing end surfaces of each layer of the light transmitting resin plate 8 constituting the light guide 14.
By filling the light guide 14, it is possible to suppress uneven illumination due to the diffused light on the diffusion end face, and it is also possible to obtain the effect that the light guide 14 can be made into a simple rectangular parallelepiped.

[0028] In addition to the first or second embodiment described above, the technology applied in the conventional structure is further used,
By applying a hairline treatment or matte treatment to the bottom surface of the light guide 13 or 14 or by forming a colored layer 7 at the position of the light guide 13 on the base printed wiring board 4,
More effective diffused illumination can be achieved.

[0029]

Effects of the Invention As described above, according to the present invention, each light beam is A lighting module is provided that can appropriately distribute the light diffusion surface of the end of the transparent resin plate on the side far from the light source in a region far from the light source, and can effectively improve variations in diffused illumination caused by a light guide. can be provided.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view schematically showing the cross-sectional structure of a lighting module according to a first embodiment of the present invention.

FIG. 2 is a top view showing the configuration of the illumination module in FIG. 1 viewed from above.

FIG. 3 is a cross-sectional view schematically showing a cross-sectional structure of a lighting module according to a second embodiment of the present invention.

FIG. 4 is a cross-sectional view schematically showing the cross-sectional structure of a conventional sidelight type lighting module.

5 is a top view showing the configuration of the illumination module in FIG. 4 viewed from above.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1... LED element, 2... Light source mounting printed wiring board, 4... Base printed wiring board, 8... Light-transmitting resin board, 9... Diffusion end surface, 10... Light diffusion resin, 12... Incident end surface, 13, 14...
light guide.

Claims (2)

[Claims] 1. A pair of substrates each having a light emitting element as a light source mounted thereon and disposed with the surfaces on which the light emitting elements are mounted facing each other; and a light guide formed by laminating a plurality of light-transmitting resin plates formed with gradually different dimensions corresponding to the distance from the light source with their side ends aligned on the light source side. A lighting module featuring: 2. The lighting module according to claim 1, wherein a concave portion formed at a location far from the light source by laminating each resin plate of the light guide plate is filled with a resin having light diffusing properties.