JP2544134B2 - A plate-shaped optical transmitter for obtaining a planar light source - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a plate-shaped optical transmission body for obtaining a planar light source, and more specifically, radiates light incident from an end face of a plate-shaped substrate from the surface side of the plate-shaped substrate. However, the present invention relates to an optical transmission body that can use this radiated light for illumination, display, and the like.

[Prior Art] Conventionally, as a technology using laminated sheet-shaped light guides as an optical transmission body, Japanese Patent Laid-Open Nos. 60-149004 and 607-7 are available.
Those disclosed in 8006, 60-163403, and 58-5002 are known.

[Problems to be Solved by the Invention] However, in all of these conventional techniques, total reflection is utilized to transmit light having substantially the same luminous flux from one end to the other end of the sheet. For this reason, there is a drawback that the conventional light guide cannot be used when the external light is guided to the flat display portion having a large area such as a display.
That is, in the conventional light guide, it is common to provide a light source at the end of the light guide, but in that case, the light becomes bright near the light source, and the other light is emitted from the cross section at almost the end. As a result, it is impossible to obtain a planar light source having uniform brightness on all planes.

Further, in order to obtain a planar light source with uniform brightness, a light guide body whose thickness is reduced as the distance from the light source is increased may be used, but this is not sufficient. It should be noted that even a conventional light guide can be guided to a flat display portion having a large area by combining an optical system, but it has a drawback that the cost becomes high and the advantage of interposing a fiber is lost.

On the other hand, in JP-A-59-143202, light incident on the end face of one plate-shaped substrate is radiated in a direction perpendicular to the incident light by using a reflective film to obtain a planar light source on the surface. The technology is disclosed.

However, in this technique, the plate-shaped substrate needs to be formed thick in order to increase the amount of incident light, but this is limited and the manufacturing cost is high. Further, there is a drawback that the resin used as the light guide is limited because light is guided and radiated to the outside due to the difference in the refractive index with air. Furthermore, it is difficult to emit uniform light from all surface emitting surfaces, and therefore, in order to emit light uniformly from the surface emitting surface of such one plate-like substrate, many optical systems are combined. Therefore, there are drawbacks such that the manufacturing is not easy and the cost is high because various measures are required.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a plate-shaped optical transmission body that obtains a planar light source having a large area such as a display without the need for an optical system. .

Further, the present invention provides a plate-shaped optical transmission body that can easily meet the demand for increasing the amount of incident light and can obtain a planar light source that can widen the range of resin combination that can be used as a light guide. The purpose is to

Further, according to the present invention, the flat surface near the light source does not become brighter as seen in the conventional flat light source conductor of the display, and the flat surface can maintain the brightness evenly. An object is to provide an optical transmitter.

Still another object of the present invention is to provide a plate-shaped optical transmission body that can obtain a planar light source that is easy to manufacture and low in cost.

[Means for Solving Problems] The present inventor has accomplished the present invention as a result of extensive studies to achieve the above object.

That is, a plate-shaped optical transmission body for obtaining a planar light source according to the present invention is a plate-shaped optical transmission body for obtaining a planar light source on a surface from light incident from an end face of a light-transmissive plate-shaped substrate, It is characterized in that a light-transmitting sheet having a refractive index different from that of the base is laminated in the body so that the inner end of the base is stepwise and spaced apart.

A preferred embodiment of the present invention is that the light transmissive sheet has a refractive index higher than that of the substrate.

[Operation] In the present invention, when the laminated light-transmissive sheet has a higher refractive index than the plate-shaped substrate, for example, light incident on one layer of the light-transmissive sheet does not diffuse to the outside, The light is totally reflected at the interface, and eventually the one layer of the light transmissive sheet is refracted and advanced from the incident end toward the radiating end. The advancing light is emitted and diffused from the emission end into the substrate. Since the light transmissive sheet is longer in the lower layer, the emitted / diffused light is reflected in the direction facing the light transmissive sheet, that is, in the direction perpendicular to the incident light, and emitted from the surface of the plate-shaped substrate. This emitted light is used as display light for a display or the like, if necessary.

It is effective to provide unevenness in the plane in order to expect a more uniform radiation in the plane direction.

On the other hand, contrary to the above, when the refractive index of the laminated light-transmitting sheet is smaller than the refractive index of the plate-like substrate, the light-transmitting sheet and the substrate portion sandwiched between the light-transmitting sheets serve as the light guide section. To act.

In addition, in Japanese Utility Model Publication No. 54-46289, there is a technique in which the incident portion of the laminated light guide is stepwise and a notch portion with a reflecting structure is formed at the incident portion in order to effectively collect external incident light. Although disclosed, this technique is merely the idea of efficiently collecting incident light, and the idea of efficiently transmitting light by the combination of the light transmissive sheet and the substrate as in the present invention is fundamentally Not only is this different, but with this configuration, even if light is incident from the end face side, only a stepwise light source can be obtained, and a flat light source cannot be obtained.

[Specific Configuration] An example of a plate-shaped optical transmission body for obtaining the planar light source of the present invention will be described with reference to the accompanying drawings. FIG. 1 is an enlarged front view showing an embodiment of the present invention, and FIG. 2 is a plan view of the same.

In the figure, 1 is a light-transmitting substrate, and 2A to 2F are light-transmitting sheets.

Table 1 shows the values of the refractive index (nd) of various resins that can be used, but the resin is not particularly limited to this,
It may be an inorganic substance. The light transmissive sheet is preferably selected from those having a refractive index larger than that of the substrate 1. The material is not particularly limited, and a resin having a slight light attenuation may be used (semi-transmissive, weakly transmissive). The material is determined by the relationship with the material of the light-transmitting sheet, and it is preferable that the transmittance is high for the purpose of increasing the efficiency of light transmission, but it is not absolute.

Examples of the combination of the substrate and the light transmissive sheet are polymethylmethacrylate (PMMA) / polystyrene (PSt), P
MMA / polytetrafluoroethylene, PMMA / polyvinyl chloride (PV
C), PMMA / polyethylene terephthalate, polystyrene / polycarbonate, polycarbonate / 4-methylpentene-1 and the like.

Further, a light-scattering substance may be dispersed (particulate dispersion, phase dispersion, etc.) in the substrate 1 within a range not impairing the object of the present invention. Further, it is also preferable to include a coloring material (including a colored compound) and other additives. When the pigment substance is contained, two or more colors may be combined, and in this case, different pigment substances may be contained in different places. A reflecting member 10 is preferably provided at the right end (and / or side surface) of the base 1 in the drawing.

The light transmissive sheets need not be formed of materials having the same refractive index. Further, the substrate 1 does not have to have the same refractive index as a whole, and may have a partial difference.

In the figure, 3 is the incident end of the light transmissive sheets 2A to 2F, and 4 is its radiating end.

The incident end 3 of each of the light transmissive sheets 2A to 2F may be linearly aligned as shown, but may be curved according to the shape of an incident light source such as a fluorescent discharge tube.

The radiating end 4 of each of the light transmissive sheets 2A to 2F has a step shape, and the length of each sheet 2A to 2F that makes up this staircase
The width and the wall thickness are not limited to those shown in the figure. Further, the number of laminated light-transmissive sheets may be increased or decreased to increase or decrease the number of stairs, or the thickness of each of the sheets 2A to 2F may be different.

To stack the light transmissive sheets 2A to 2F, a gap is provided as shown in FIG. That is, when the substrate 1 located in the gap has a small refractive index and the light transmissive sheet has a high refractive index, the light x incident on the light transmissive sheets 2A to 2F as shown in FIG.
Can be reflected at the interface with the substrate 1 to be refracted and advanced in the light transmissive sheet. The difference in the refractive index between the light transmissive sheet and the base is preferably a value that allows the light in the light transmissive sheet to be totally reflected, but part of the light in the light transmissive sheet is radiated into the base. It does not mean that it is not excluded.

When a light source or an optical information source similar to the light source is placed at the left end in the drawing of the optical transmission body having the above configuration, each light transmitting sheet 2A
Light advances to the radiating end 4 in the ~ 2F. The light that has reached the emission end 4 enters the substrate 1. Of the light in the base 1, the light reaching the right side and the lower side (in the drawing) of the base 1 is provided by the reflecting member 10 and the light-transmitting sheets 2A to 2F, particularly 2F are provided below the base 1 All the light reaches the upper surface in the drawing. Since the yield of emitted light is not an essential requirement in the present invention, the reflecting member 10 is not essential. Further, the shape of the surface does not have to be flat and may be curved.

In the above-described embodiments, a device such as making the shape of the radiation end 4 an inclined surface may be added.

Next, an example of a method of manufacturing the optical transmission body shown in FIG. 1 will be described with reference to FIG.

First, the base sheet 1A for forming the base 1 is arranged,
A light-transmissive sheet 2F is placed on top of that, and a base sheet 1B is placed on the side of it. Then, the base sheet 1C is placed thereon, and 2E to 2A and 1D to 1M are sequentially placed thereon in the same manner as shown.

After the arrangement as shown in FIG. 4 as described above, pressing with heating using a heat molding machine can obtain the optical transmission body shown in FIG. This effectively utilizes the difference in melting temperature between the resin forming the base and the resin forming the light-transmitting sheet, and the base and / or the light-transmitting sheet are melted and integrally molded by hot pressing. It is a thing.

The above manufacturing method is just an example,
Of course, it can be manufactured by other methods.

The plate-shaped optical transmission body that obtains the planar light source obtained as described above can be used for display of a show window, for illumination using sunlight, and other wide-ranging applications can be expected.

In addition, as the utilization form, the fifth mode of the above-mentioned JP-A-59-143202 is used.
As shown in FIGS. 6 and 6, it is possible to arrange two or more plate-shaped optical transmission bodies in parallel, or to arrange two or more plate-shaped optical transmission bodies shown in FIG. Alternatively, the planar light source may be obtained on the front and back surfaces by preliminarily manufacturing in steps from the center toward the front and back surfaces.

[Effect] According to the present invention, a planar light source having a large area such as a display can be obtained without the need for an optical system.
Also, it is easy to meet the demand for increasing the amount of incident light,
The range of combinations of resins that can be used as the light-transmissive sheet can be widened, and the present invention has an effect of providing a plate-shaped light transmission body that is easy to manufacture and can obtain a low-cost planar light source.

The plate-shaped optical transmission body of the present invention may be manufactured in a wavy shape, a bow shape, or another curved shape, or may be heat-deformed during use.

[Brief description of drawings]

FIG. 1 is an enlarged front view showing an embodiment of the present invention, FIG. 2 is a plan view of the same as above, FIG. 3 is an enlarged front view of a main part of a light transmitting sheet in the embodiment of the same above, and FIG. It is an expansion front view which shows an example of the manufacturing method of a transmission body. 1: Substrate 2A to 2F: Light transmissive sheet 4: Radiating end

Claims (2)

(57) [Claims] 1. A plate-shaped optical transmission body that obtains a planar light source on its surface from light incident from an end face of a light-transmissive plate-shaped substrate, wherein the plate-shaped substrate has a light-transmitting property different from that of the substrate. A plate-shaped optical transmission body for obtaining a planar light source, characterized in that sheets are laminated such that the inner ends of the substrate are stepwise and spaced apart. 2. A plate-shaped optical transmission body for obtaining a planar light source according to claim 1, wherein the light-transmissive sheet has a refractive index higher than that of the substrate.