JPH09159833A - Light transmission body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a uniform and thin large-area light transmission body which has neither local luminance irregularity nor luminance irregularity over the entire light emission surface by projecting primary light which is made incident on the light transmission body from its projection surface with efficiency. SOLUTION: This light transmission body 3 is transparent and constituted by arranging many dotted, solid-line, or broken-line projection bodies, which guide light from at least one side end surface and formed on the reverse surface on the opposite side from the light projection surface, with low density nearby a primary light source and with high density at a distance from the linear light source so that the triangular pattern of the section crossing the axis of the linear light source at right angles has a nearly uniform luminance distribution of the projection light from the projection surface. Here, it is preferable that 0.1<=H/W<=0.6 and 20<=W<=200, where W is the sectional width of the triangular pattern and H is the height.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light guide for a surface light source used in a liquid crystal display device or the like, and the light guide of the present invention is used as a back lighting device for a liquid crystal display device such as a word processor, a personal computer or a thin television. It can be used effectively.

[0002]

2. Description of the Related Art A surface light source device having a light guide of a so-called edge light system, which is made to enter from a side end surface of a transparent plate and emit light from one surface (light emitting surface) thereof for illumination. However, it is used as a back lighting device of a liquid crystal display device provided in a word processor, a personal computer, a flat-screen television, or the like. In such a surface light source device, generally, a tubular light source is arranged on one side end surface of the light guide body or on two side end surfaces orthogonal to each other or opposite to each other, and the remaining portion of the light guide body excluding the incident side end surface and the light emission surface. The surface and the backside of the tubular light source are configured to be covered with a light reflector.

In order to uniformly and efficiently emit the primary light incident from the side end surface of the light guide body from the entire light emitting surface of the light guide body, the light guided to the light guide body is directed in the traveling direction. When diffusely reflecting in the orthogonal direction, the scattering reflection ability near the light source is low, and the scattering reflection ability in the farthest part from the light source is high, and most of the incident primary light is emitted from the emission surface. Need to be attached. Various principles and processing methods for imparting such a scattering / reflecting ability have been proposed as follows, and some of them have been put into practical use.

Mainly composed of a rough surface A surface of the light guide body on which the entire light emitting surface or the opposite surface thereof is uniformly roughened (Japanese Patent Laid-Open No. 3-118593, Japanese Patent Laid-Open No. 6-118248, etc.) ) Or the one with a different surface roughness (Japanese Patent Laid-Open No. 63-168604, etc.)
Or a pattern in which spotted or linear rough surface patterns are arranged with different area densities (JP-A-4-162002).
Issue gazette). The roughening method is carried out by sandblasting or chemical etching of a mold, and the roughening pattern is formed by a combination of photoetching and sandblasting (JP-A-4-52286). Application of a scattering reflector A scattering reflection substance containing white paint or fine particles is applied in a dot pattern or a linear pattern on the back surface opposite to the light emitting surface by a screen printing method or the like (JP-A-57-12838).
In Japanese Patent Laid-Open No. 1-245220, etc.), the manufacturing process consists of two processes, a patterning process for a mirrorless plate without a pattern and a pattern printing process. Bulk diffusion mainly uses light-guiding bulk resin itself as a light-diffusing scatterer by mixing light-diffusing fine particles, blending incompatible polymer, copolymerization, etc. (JP-A-1-172801, JP-A-2) -22
1924, JP-A-5-249319, and JP-A-6-186560). Concavo-convex patterns are roughly classified into the following three types. The manufacturing method is carried out by mechanically cutting the light guide itself or the molding die, laser processing, die etching and the like. 1) Concave pattern A concave pattern is arranged on the emission surface or the opposite surface with reference to a flat surface. For example, one-dimensional linear triangular groove (JP-A-2-165504, JP-A-6-3526), rectangular groove (JP-A-6-123810, JP-A-6-23810).
No. 265731, etc.), semi-circular groove (Actual flat number 5-795)
No. 37), and a broken-line triangular groove (Japanese Patent Laid-Open No. 5-196936).
Japanese Patent Laid-Open No. 5-216030).
Further, a two-dimensional conical or pyramid-shaped engraving (Japanese Patent Laid-Open No. 4-278922), a hemispherical engraving (Japanese Patent Laid-Open No. 6-289393, etc.), and a cylindrical engraving (Japanese Utility Model Publication No. 1-145902). There is. Further, the inner surface of the pattern recess is roughened (Japanese Patent Laid-Open No. 4-355).
No. 408, Japanese Utility Model Laid-Open No. 5-94802, etc.) have also been proposed. 2) Convex pattern A convex pattern is arranged on the emitting surface or the opposite surface with reference to a flat surface. For example, one-dimensional linear triangular convex (Japanese Unexamined Patent Publication No. 5-313163, Japanese Unexamined Patent Publication No. 6-75123), rectangular convex (Japanese Utility Model Laid-Open No. 5-79537), semicircular convex (Japanese Unexamined Patent Publication No. 6-281928). ). In the two-dimensional shape, there is a hemispherical convex (Japanese Patent Laid-Open No. 5-79537, Japanese Patent Laid-Open No. 6-281929, etc.). Further, there are also those in which these convex portions are roughened (Japanese Utility Model Laid-Open No. 5-94802, Japanese Patent Laid-Open No. 6-186562, etc.). 3) Concavo-convex pattern A pattern in which a one-dimensional sawtooth pattern or a two-dimensional lattice-like pattern is arranged without a flat surface on the emitting surface or its opposing surface. For example, one-dimensional sawtooth (JP-A-64-11203, JP-A-6-250024, etc.), two-dimensional grid-like (JP-A-62-278505, JP-A3-1)
No. 89679, etc.), and further roughened (JP-A-6-342159, JP-A-6-1238).
No. 85).

In addition to the conventional demands for high brightness and high uniformity, in recent years, demands for large screens, thin, lightweight, and low power consumption are increasing more and more. Scattering reflection pattern by injection molding method, which is shifting from the flat light guide that has been done to the taper light guide that becomes thinner and lighter, and which does not require the pattern printing process required in the above technology. It is said that a method of simultaneously forming the is also desirable in terms of cost.

[0006]

From this point of view,
There are the following problems in each method. It is possible to mass-produce a uniformly roughened surface by an injection molding method using a metal mold, but to obtain uniform brightness as a surface light source, 1
The mold is complicated because there is a need for a wedge shape with a complicated curved surface that makes the entrance part of the next light source sufficiently thick and thin away from the light source, and there are restrictions on the flexibility of the light guide shape. In addition, there is a problem that there is a limit in thinning the light guide in a large area. There are also proposals to change the roughness, but it is difficult to realize. On the other hand, the method of distributing the rough surface as spots or linear patterns is a relatively excellent method in which the shape of the light guide can be set freely and the brightness can be made uniform in the pattern design. In addition, there is a high risk due to an unstable factor in the die fabrication such as a variation between the pattern formation accuracy of photo etching and the roughening treatment such as blast in the next step.

The printing method according to the above is the method most practically used in the conventional flat plate type light guide. However, the first problem is that the pattern printing is a separate step, so that the patterns are simultaneously formed by the injection molding method or the like. There is no cost advantage compared to the method. Furthermore, the limit of printing accuracy (Japanese Patent Laid-Open No. 4-2898)
No. 22), the pitch of the dots of the scattering reflection pattern cannot be made smaller than about 1 mm (JP-A-5-100).
No. 118). Further, due to the problem of the printing accuracy, the reproducibility of the minimum point and the minimum line is poor at the time of pattern printing, and the production yield is lowered and the cost is increased (JP-A-3-9304 and JP-A-4-278922). See the bulletin). In terms of performance, since the pattern is rough, there is a local brightness difference between the part with the pattern and the part without the pattern, which causes uneven brightness. It is usually provided to make local uneven brightness due to pattern roughness uniform. However, since a diffuser plate or a diffuser sheet having a high diffusion efficiency has a low total light transmittance, a loss is caused and the brightness is lowered (Japanese Patent Laid-Open No. Hei 5).
-100118, and JP-A-6-265732).

When the rough patterns are regularly arranged, due to the local uneven brightness, a prism sheet or a liquid crystal panel is provided on the light emitting surface of the light guide for the purpose of increasing the brightness in the vertical direction. Moire is generated between them, which causes harmful effects. In order to prevent this, the pattern intervals are randomly arranged (see Japanese Patent Laid-Open No. 5-313017 and Japanese Patent Laid-Open No. 6-130317).
No. 242,442), the ridge line direction of the prism sheet is arranged obliquely with respect to the pattern arrangement direction (Japanese Patent Laid-Open No. Hei 5)
No. 257144 and Japanese Patent Application Laid-Open No. 6-230228) have been proposed, but the design and assembly costs are high.

The method described above can be mass-produced by injection molding or the like, and in principle, it is expected that there will be no local uneven brightness due to patterns, but it seems difficult to achieve uniform brightness only by the bulk scattering method. . Further, it is not easy to give a light diffusion performance distribution to the light guide bulk itself, and mass production is expected to be difficult. Furthermore, in order to achieve uniform brightness with the resin material of the uniform diffusing agent, it is necessary to change the thickness of the taper shape, etc., or it is necessary to form a concavo-convex pattern. There is a possibility that it will become complicated, such as when it is necessary to do so, or that restrictions on the shape of the light guide will become a serious problem.

The method described above is a method excellent in mass productivity, which is premised on pressing using a mold and injection molding. Mechanical cutting, laser processing, chemical etching and the like are disclosed as means for achieving the uneven pattern. However,
With respect to the pattern shape accuracy, the dimensional accuracy, and the roughness of the pattern forming surface in any of the processing methods, the larger the area of the fine pattern, the more difficult the processing in terms of stability, reproducibility, and cost, and the higher the risk. What has been put into practical use to date is a light guide of several inches in size, and the pattern pitch is still up to about 1 mm, which cannot be avoided due to the problem of the roughness of the pattern. In addition, even in the case of forming a relatively large uneven surface and then roughening the uneven surface, the unevenness of the roughening process is added to the problem of the accuracy of forming the uneven surface, and the instability of the mold making becomes unstable. This causes a problem in terms of cost for producing a mold.

An object of the present invention is to efficiently emit the primary light that has entered the light guide from the emission surface, and to provide a uniform, thin and large area with no local luminance unevenness or luminance unevenness on the entire light emitting surface. It is to provide a light guide.

[0012]

In order to achieve the above object, the edge light type light guide of the present invention has the following features. That is, it is a transparent light guide body that guides light from at least one side end face, and is a spot-like, solid line-shaped, or broken-line-shaped convex object on the back surface opposite to the light emission surface, and A large number of triangle-shaped patterns, each of which has a triangular cross-section, are placed at low density near the primary light source and at high density far away so that the luminance distribution of the light emitted from the emission surface is approximately uniform. It is characterized by having done. here,
When the cross-sectional width of the triangular pattern is W and the height is H, the H / W ratio is 0.1 ≦ H / W ≦ 0.6, and the cross-sectional width W (μm) of the triangular pattern is 20 ≦ W ≦
It is preferably 200 respectively.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
FIG. 1 is an embodiment of the present invention, and FIG. 1A is a cross-sectional view of a cross section orthogonal to the axis of a linear primary light source, showing a scattering reflection surface 3a of a light guide 3 made of a transparent material. In 3b, triangular convex patterns 3a are provided at a low density in a portion close to the primary light source 1, and at a high density in a distant place. The arrangement of the light sources is not limited to the one-lamp type, but the two arranged so as to face each other.
A light type may be used, or an L-shaped light source may be used to guide light from two end faces that are orthogonal to each other. In addition, a reflecting plate or a reflecting sheet 4 is arranged on the scattering / reflecting surfaces 3a and 3b through an air layer 7. FIG. 1B is a plan view of the scattering / reflecting surface of the light guide body 3, and shows an example in which the pattern 3a has a spotted shape, a chain line shape, or a linear shape. The spots may be circular or polygonal. The chain line may be formed by connecting solid lines having rounded ends or by connecting rectangular solid lines.
The plurality of pattern shapes viewed from the plane direction are not limited to the same shape, and may be a combination of spots, chain lines or straight lines, and the sizes and widths of a plurality of patterns may be changed. As the transparent material of the light guide, polystyrene, polycarbonate, ABS resin, or the like, as well as acrylic resin, and a light-scattering resin in which different kinds of polymers are dispersed may be used.

FIG. 2 is a partially enlarged view of the cross section of FIG. 1. The light beam from the primary light source propagates in the light guide body while being totally reflected by the light guide body emission surface 3c and the smooth surface 3b of the scattering / reflecting surface facing the light guide body. To do. The light beam incident on the convex pattern 3a of the scattering / reflecting surface is reflected and refracted depending on the pattern, part of which is directly emitted from the pattern, or part of which is reflected by the reflection plate 4 and emitted from the emission surface 3c.

Regarding Pattern Shape FIG. 3 shows the behavior of catadioptric refraction in a unit pattern of rays incident on a convex pattern. As shown in FIG. 3A, the light ray L0 incident on the substantially trapezoidal pattern 3a in cross section
Is totally reflected by the tops AB and BC, and the side AC
After returning to the inside of the light guide body through, the light exits from the exit surface 3c within the critical angle of total reflection and is totally reflected again to become propagating light. It can be said that the pattern in which the proportion of the light ray L1 that does not contribute to the emission is large among all the light rays L0 incident on the pattern is a pattern having low scattering and emission efficiency. However, since this ray becomes propagation light again, it does not involve the loss described later.

In FIG. 3B, the pattern incident light L0 is totally reflected by the hypotenuses BC and CD, and becomes a light ray L2 which is emitted from the emitting surface 3c beyond a critical angle. Light rays emitted through only total reflection due to such a pattern have the lowest loss and high light utilization efficiency.

In FIG. 3 (c), the incident light L0 is totally reflected by the oblique side AB or is refracted and transmitted directly from the oblique side BC and is once emitted to the air layer 7. However, since the incident light L0 is directed upward, the reflection / scattering surface is smooth. Re-enters the surface 3b. Smooth surface 3b and exit surface 3c
Are almost parallel to each other, the light ray L3 is emitted from the emission surface 3c. This light ray L3 is also a light ray with a small loss like the light ray L2, but since it passes through the surface corresponding to the side BC, which is two interfaces having different refractive indices, and the scattering emission smooth surface 3b, it causes reflection loss at the two interfaces. Occurs, and the light utilization efficiency is reduced. For example, the light guide is acrylic resin (refractive index 1.49)
In the case of the interface between air and air (refractive index 1.00), reflection loss of about 4% occurs in at least one interface, and about 8% occurs in two interfaces. Especially, since the incidence on the 3b interface is not vertical, the reflection loss is further increased. Grows big Not all of this 8% of the reflected light is lost, but part of it is reused as a light beam traveling in the opposite direction in the light guide, and part of it is reflected by the reflector or the reflection sheet 4 on the back surface. Therefore, the light is emitted from the emitting surface and used. However, such light rays are mostly lost as stray light having lost directionality and cannot be used.

In FIG. 3D, the incident light L0 is directly on the hypotenuse CD.
The light is refracted and transmitted through the air layer 7 and is incident on the reflection sheet 4 with the refraction angle facing downward. The reflection sheet is a diffuse reflection sheet or a specular reflection sheet formed by metal vapor deposition. As long as the light rays reflected here hit the scattering reflection mirror surface 3b, most of them are the light rays L from the light guide emission surface.
Emit as 4. However, when the reflection sheet is a diffuse reflection sheet, the reflection sheet reflects not only in the vertical direction but also in a direction close to the horizontal direction and does not re-enter the light guide body. Reflection loss occurs. Also, when the reflection sheet is a metal specular reflector, the reflectance is generally about 80 to 90%,
There is absorption loss at the reflector. Therefore, such a light ray L4 has the largest loss in terms of light utilization efficiency.

As described above, by considering the ratio of the light ray L0 incident on the unit convex pattern having a triangular cross section to L1, L2, L3, and L4, the scattering reflection performance of the unit pattern and the effective use of the light ray are considered. You can evaluate the efficiency. A pattern having a large proportion of scattered light rays L2 + L3 + L4 with respect to all incident light rays L0 to the pattern has a high scattering emission efficiency. Further, the larger the ratio of the scattered light rays L2, L3, L4 is, the smaller the loss is, and the light utilization efficiency is higher. Can be said to be a high pattern.

The inventors of the present invention have a pattern width W, a pattern height H, and a triangle convex pattern ABC of an acrylic light guide (acrylic refractive index 1.49, air refractive index 1.00) as shown in FIG. The vertex position d (0 in the width direction of the triangle vertex B
≦ d ≦ 1) is changed, and the incident angle θ =
The ratio of the scattered light to L1 to L4 was calculated assuming that the light is incident at a critical angle θ = θc (= 47.8 °) from 0 °. The incident position is each equal point obtained by dividing the incident side AC into 100 equal parts, and the incident angle is θ =
0 to θc are divided into 100 equal parts, and a total of 10,000 equal-intensity rays are generated as incident rays L0, and specular reflection / refraction at sides AB and BC are calculated, and scattered rays L1 to L4 are totaled and totaled. The ratio to the ray L0 was calculated. It should be noted that when the position of the triangle vertex B is on the left side of A or the right side of C, the feasibility in peeling the mold and the molded product at the time of molding is small, and thus it was excluded.

By changing the vertex position d, L with respect to H / W
5 to 9 show the results of calculating the respective ratios of the total incident light L0 to the total incident light L2, L3, L4 and the like. L1 + L2
The sum of the respective ratios of + L3 is the pattern scattering reflection efficiency (hereinafter referred to as η), whichever case (FIGS. 5 to 9).
In the case of H / W <0.1, η <0.6 and the efficiency is low.
When H / W> 0.5, η = 1.0 and saturation occurs. H / W
<0.1, that is, the pattern width is 1 with respect to the pattern height
When it becomes 0 times or more, η <0.6, so that the scattering reflection efficiency is low as a unit pattern. On the contrary, H / W
When> 0.6, the scattering reflection efficiency η becomes saturated, and even if the pattern height is extremely increased with respect to the pattern width, the difficulty in cutting and molding the die is only increased, and there is no effect. Shows.

When the apex position d <0.2 (FIGS. 5 and 6) is small, η is low when the H / W is small, and the scattering reflection performance is poor. On the contrary, when d> 0.8, H / W where η is saturated
Becomes higher and disadvantageous. Therefore, for the scattering / reflecting performance, it is preferable that 0.2 ≦ d ≦ 0.8.

For the effective use efficiency of light rays, the incident light ray L0
It is preferable that the ratio of L2 and L3 is large. From this viewpoint, L2 + L3 is preferable because the value of d is small in the range of 0.1≤H / W≤0.6. Therefore, from the viewpoints of scattering reflection efficiency, light utilization efficiency, and moldability, 0.1 ≦ H / W
It is preferable that ≦ 0.6.

Fine Pattern The triangular fine convex pattern of the present invention can be formed using a mold. It is desirable that the patterns are fine in order to prevent local uneven brightness due to the individual patterns. Interference color due to fine structure (Japanese Patent Laid-Open No. 6-160636)
It is preferable that it is sufficiently large so as not to appear), and that it is sufficiently small so that uneven brightness is not noticeable.
The thickness is preferably about 300 μm, more preferably 20 to 200 μm. When forming a pattern on a die, it is easy to cut if the pattern is simple and the depth H is shallow with respect to the width W.
Shallow patterns with ≤0.6 are preferred.

Surface accuracy It is important that the smooth surface 3b of the light guide member is a mirror surface in order to totally reflect the light and guide the light away from the light source without loss due to scattering. Therefore, it is important that the smooth surface 3b of the light guide is smooth, and the surface roughness is preferably 0.2 μm or less. In terms of the reflection / scattering efficiency of the pattern, the light utilization efficiency, and the reproducibility, the surface roughness of the surface corresponding to the hypotenuses AB and BC of the triangular pattern is preferably 0.2 μm or less.

Advantages of Convex Pattern The scattering reflection characteristic of the triangular convex pattern is that the opening of the convex pattern provided on the basis of the scattering reflection surface 3b as described above, that is, the side AC of the triangle ABC in FIG. It is sufficient to consider only the incident light rays, and even if the patterns are densely arranged, the influence of adjacent patterns is small, and the pattern density design for uniform brightness is easy. However, the concave pattern is complicated. 10A and 10B are explanatory diagrams of ray tracing using a trapezoidal concave pattern, where FIG. 10A shows a case where the patterns are arranged at a low density, and FIG. 10B shows a case where the patterns have a high density. Focusing on the triangle ABC which is one pattern, the side AB is effective for scattering reflection.
The side AB corresponds to the opening of the convex pattern, that is, the side AC. In the case of the low density of (a), the light rays that can be incident near the point A on the side AB are in the angular range of α1, and the rays in the angular range of α2 are incident near the point B. The same applies to each incident point in the middle portion of the side AB. The sum of all the rays that can enter the side AB is the opening of the triangular concave pattern ABC,
It is clear that the opening in (b) is smaller than that in (a) because the patterns are adjacent to each other. That is, when the pattern density is low, the scattering / reflecting performance of the unit pattern is high, and when it is high, the scattering / reflecting performance is low, and the scattering / reflecting performance of the unit pattern complicatedly changes depending on the pattern arrangement density. Since the concave pattern is accompanied by such complexity, it is extremely difficult to design the pattern density for uniform brightness.

Generally, on the smooth surface of the light guide having air as an interface,
When a diffusing sheet or a scattering / reflecting sheet having minute irregularities is brought into contact with the light, the light is scattered and leaks out of the light guide system at the contact point. This situation varies greatly not only with the finely rugged surface state of the diffusion sheet or the reflection sheet but also with the pressing pressure. A general backlight has a configuration including such a situation, and the brightness as a surface light source becomes unstable. The smooth surface 3b on the pattern forming surface is important as a total reflection surface of the light guide, and it is desirable that there is no such instability. From this point, the smooth surface 3b should be in contact with the diffusion sheet or the reflection sheet if it is a convex pattern. There is no. For the above reasons, the convex pattern is preferable.

Pattern Density Distribution Generally, in order to make the brightness uniform as a surface light source, the pattern density is designed to be low in a portion near the primary light source and high in a distance from the light source. Although the present invention does not limit the pattern distribution, the following are important in the pattern distribution design.

First, a method of providing a density distribution by changing the interval between unit patterns having the same plane shape such as spots, chain lines, and straight lines is advantageous in designing a uniform brightness.
The reason for this is that the design and the actual situation do not usually follow the theory, because the problems of the overall shape of the light guide itself and the shape processing accuracy of the pattern are involved. At the initial stage, the reproducibility of processing must be improved, and trial production and evaluation of the luminance distribution must be repeated to empirically determine the parameters. At that time, in the same light guide, when the plane shape of the pattern is changed as shown in FIG. 1B or the cross-sectional shape or size is changed as shown in FIGS. Since the reflection performance changes intricately, in addition to the problems of processing accuracy and reproducibility, uncertainties increase, making it difficult to design for uniform brightness.

Secondly, a pattern having high scattering and reflection performance is preferable so that all the light rays incident on each pattern are emitted from the emission surface as much as possible without loss. In the case of a pattern having low scattering / reflecting performance, the scattering / reflecting performance is particularly insufficient at a position far from the primary light source, which makes it difficult to design a highly efficient pattern distribution. For high-intensity pattern design, it is desirable to design such that most of the light is emitted from a position near the light source to the distant portion, and the remaining light is emitted with a scattered reflection distribution close to 100% in the distant portion. . In the case of a triangular pattern, it is possible to form a highly scattering reflecting surface formed only by the triangle 3a so that the scattering reflecting surfaces 3a and 3b do not have the smooth surface 3b.

As described above, in designing the pattern distribution, first, it is rational to arrange unit patterns whose cross sections of the same shape having high reflection / scattering efficiency are triangular with different intervals, and to correct slight uneven brightness. For the pattern shape,
It is better to increase or decrease the width and length.

For this reason, the cross-sectional shape is a triangular convex shape, and the ratio of the width W to the height H is 0.1 ≦ H / W.
In the case of ≤0.6, it is preferable to design the pattern density by arranging a large number of fine patterns having a light beam utilization efficiency and a scattering / reflection efficiency and having a sectional width W (μm) of 20≤W≤200.

[0033]

EXAMPLES The present invention will be described based on examples. Width W = 100μm and depth 40μm (H / W =
Section 0.4) was cut with a straight groove having an isosceles triangular cross section. 1 made of acrylic resin using this mold
A light guide 3 having a 0-inch size and a wedge-shaped cross section as shown in FIG. 1 was injection-molded. The cross-sectional shapes of a large number of provided patterns 3a were substantially the same, the transfer formability of the patterns and the release from the mold were good, and the patterns could be easily molded. When the cold cathode tube 1 having a diameter of 2.6 mm was used as the primary light source on the end face on the long side of the thickness of the light guide body, the reflection sheet 4 was arranged on the back surface of the scattering reflection pattern, and visually observing from above, it was found that localities due to pattern roughness The brightness unevenness could not be observed and was uniform. Further, the diffusion sheet 5 is provided on the emission surface 3c, and the prism sheet 6 is further provided.
When each of them was arranged one by one and the brightness distribution was measured, it was found that the brightness uniformity was good and the light guide body was bright and uniform with high average brightness.

[0034]

According to the present invention, a light guide having high brightness and excellent brightness uniformity can be obtained.

[Brief description of the drawings]

FIG. 1 is a configuration example of an illumination device using an edge light type light guide according to the present invention.

FIG. 2 is a partially enlarged explanatory view of an edge light type light guide according to the present invention.

FIG. 3 is a classification diagram of scattered reflected rays having a triangular convex pattern in cross section.

FIG. 4 is an explanatory diagram of a ray tracing simulation of a convex pattern having a triangular cross section.

FIG. 5 is a diagram showing a calculation result of a ray tracing simulation of a convex cross-sectional triangular pattern.

FIG. 6 is a diagram showing a calculation result of a ray tracing simulation of a convex cross-section triangular pattern.

FIG. 6 is a diagram showing a calculation result of a ray tracing simulation of a convex cross-section triangular pattern.

FIG. 7 is a diagram showing a calculation result of a ray tracing simulation of a convex cross-sectional triangular pattern.

FIG. 8 is a diagram showing a calculation result of a ray tracing simulation of a convex cross-section triangular pattern.

FIG. 9 is a diagram showing a calculation result of a ray tracing simulation of a convex cross-section triangular pattern.

FIG. 10 is an explanatory diagram of ray tracing of a light guide having a concave cross-section triangular pattern.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Primary light source 2 ... Reflector 3 ... One embodiment of light guide according to the present invention 4 ... Reflector or reflective sheet 5 ... Diffuser or diffuser sheet 6 ... Prism sheet 7 ... Air layer

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[Procedure amendment]

[Submission date] February 26, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Brief description of drawings

[Correction method] Change

[Correction contents]

[Brief description of the drawings]

FIG. 1 is a configuration example of an illumination device using an edge light type light guide according to the present invention.

FIG. 2 is a partially enlarged explanatory view of an edge light type light guide according to the present invention.

FIG. 3 is a classification diagram of scattered reflected rays having a triangular convex pattern in cross section.

FIG. 4 is an explanatory diagram of a ray tracing simulation of a convex pattern having a triangular cross section.

FIG. 5 is a diagram showing a calculation result of a ray tracing simulation of a convex cross-sectional triangular pattern.

FIG. 6 is a diagram showing a calculation result of a ray tracing simulation of a convex cross-section triangular pattern.

FIG. 7 is a diagram showing a calculation result of a ray tracing simulation of a convex cross-sectional triangular pattern.

FIG. 8 is a diagram showing a calculation result of a ray tracing simulation of a convex cross-section triangular pattern.

FIG. 9 is a diagram showing a calculation result of a ray tracing simulation of a convex cross-section triangular pattern.

FIG. 10 is an explanatory diagram of ray tracing of a light guide having a concave cross-section triangular pattern.

DESCRIPTION OF SYMBOLS 1 ... Primary light source 2 ... Reflector 3 ... One embodiment of light guide according to the present invention 4 ... Reflector or reflective sheet 5 ... Diffuser or diffuser sheet 6 ... Prism sheet 7 ... Air layer

Front page continuation (72) Inventor Kozo Yasuda 36 Towada, Kamisu Town, Kashima District, Ibaraki Prefecture Kuraray Co., Ltd.

Claims (3)

[Claims] 1. A linear light source, which is a transparent light guide body that guides light from at least one side end face, and is a spot-shaped, solid line-shaped, or broken-line-shaped convex object on the back surface opposite to the light emission surface. In a triangular pattern whose cross section is orthogonal to the axis of, the area near the primary light source has a low density and the area far from the primary light source has a high density so that the luminance distribution of the light emitted from the emission surface is approximately uniform. An edge light type light guide characterized by arranging a large number of light guides. 2. When the cross-sectional width of the triangular pattern is represented by W and the height thereof is represented by H, the ratio of H / W is 0.1 ≦ H / W.
The light guide according to claim 1, wherein ≦ 0.6. 3. The light guide according to claim 1, wherein the cross-sectional width W (μm) of the triangular pattern is 20 ≦ W ≦ 200.