JPH075326A - Hollow light guide plate body and hollow light guide plate using the same - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a light-weight hollow light guide plate body capable of emitting light with high brightness and high uniformity and a hollow light guide plate using the same. [Structure] A flat light-reflecting layer (2a) and a light-emitting layer (2b) that is smoothly curved in one axis, and a light-reflecting layer (2a) and a light-emitting layer (2b) are provided on one end side of the curved axis. And the light emitting layer (2b) on the other end side are arranged via the air layer (4) so that the light emitting layer (2b) can be in contact with the light reflecting layer (2a), and the light reflecting layer (2a) and the light emitting layer. (2b), at the end of the air layer (4) on the opposite side, the light source (2c) is arranged linearly in a direction substantially perpendicular to the surface including the curved axis, and the light emitting layer (2b) is , The outer surface is smooth (2
In b1), the inner surface facing the light reflection layer (2a) has a large number of prism bodies.
(P) is composed of a flexible translucent sheet (22) composed of continuous prismatic concavo-convex surfaces (2b2) arranged in parallel with each main axis substantially perpendicular to the curved axis.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hollow light guide plate body and a hollow light guide plate using the same. More specifically, the present invention relates to a backlight light guide plate for various surface illumination devices, and particularly to a sidelight type hollow light guide plate body and a hollow light guide plate suitable for a display device using liquid crystal.

[0002]

2. Description of the Related Art A display device using liquid crystal has been put to practical use as an alternative to a conventional cathode ray tube because of its reputation for low power consumption and thin shape, and it is especially noticed as a large screen display device. ing. In such a liquid crystal display device, since the liquid crystal itself does not emit light, a light guide plate for a backlight that illuminates the liquid crystal from the back side to make it visible is required. As the above-mentioned light guide plate, for example, one using a so-called edge-lighting technique in which light is incident from a side surface of a transparent flat plate (acrylic plate) and emitted from a large flat plate surface is generally used, and these are generally medium. It is made up of substantive ones.

By the way, the liquid crystal display device tends to increase in size, and accordingly, the light guide plate also needs to have a large size, but there is a problem that the weight increases with the increase in size. In order to reduce the weight, the light guide plate is made hollow. As an example of this,
An example is one in which a light-transmissive flat plate is formed into a hollow structure to form a hollow light guide plate base, a light reflecting layer is formed on one of the two large surfaces of the base, and the other surface is used as a light emitting surface.

However, in such a hollow light guide plate, both the outer surface and the inner surface of the hollow light guide plate base are flat surfaces, and the light introduced from the side end surface is directed toward the light reflecting layer and the light exit surface side. The light is guided through the base by repeating reflection between the inner flat surface and the refraction on the light output surface side to emit light. As a result, the light is diffused and attenuated in the light guide direction, so that it is not possible to expect a high-luminance light emission and the luminance is uneven.

On the other hand, as a high-brightness surface light source element, for example, a side light type solid light guide plate is used in combination with a light-transmitting sheet having one surface smooth and the other surface made of a prism group. It is known that the smooth surface of the solid light guide plate is arranged so as to face the light exit surface of the solid light guide plate (Japanese Patent Laid-Open No. HEI 2).
No. 84618). However, the translucent sheet is not a component of the light guide plate, and is arranged in parallel with the light exit surface of the light guide plate and is used to convert the exit direction from the light exit surface to the normal direction. After all, this surface light source element has high brightness in the viewing angle range only in the specific direction.

[0006]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a light-weight hollow light guide plate body capable of emitting light with high brightness and high uniformity and a hollow light guide plate using the same. is there.

[0007]

According to the invention according to the "claim 1" of the present application, the "flat light reflecting layer (2a),
A light emitting layer (2b) that is smoothly curved in the uniaxial direction, the light reflecting layer (2a) and the light emitting layer (2b) face each other on one end side of the curved axis and the light emitting layer (2b) on the other end side. 2b) is arranged via an air layer (4) so that it can contact the light reflection layer (2a), and the air layer end on the side where the light reflection layer (2a) and the light emission layer (2b) face each other. The light source (2c) is linearly arranged in a direction substantially perpendicular to the surface including the curved axis, and the light emitting layer (2b) is formed on the outer surface (2b).
1) is a smooth surface, and the inner surface (2b2) facing the light reflection layer (2a) is a continuous prism concavo-convex surface in which a large number of prism bodies (P) are arranged in parallel in parallel with each main axis substantially perpendicular to the curved axis. There is provided a hollow light guide plate body (2) 'characterized by comprising a flexible translucent sheet (22) made of

In the hollow light guide plate body (2) of the present invention, the light emitting layer (2b) is composed of a flexible transparent sheet (22). One surface (2b1) of the translucent sheet (22) is a smooth surface,
As the other surface, a continuous prism concavo-convex surface in which a large number of prisms (P) are arranged in parallel with their principal axes in parallel is used. The translucent sheet (22) is used so that the smooth surface faces the outer surface of the light guide plate body and the concavo-convex surface of the continuous prism faces the light reflection layer (2a) inside the light guide plate body. Further, the translucent sheet (22) is used by smoothly bending in the uniaxial direction, and at this time, each prism body of the continuous prism uneven surface (P)
The main axis of is set in a direction substantially perpendicular to the curved axis.
As a result, the axis of the linearly arranged light source and the principal axis of each prism are arranged in a parallel or substantially twisted arrangement, and the direct light from the light source and the reflected light from the light reflection layer (2a) are efficiently reflected, refracted, and transmitted. It will be possible. As the translucent sheet (22),
From the viewpoint of strength, translucency, refractivity, etc., those made of polycarbonate are preferable, and those made of acrylic copolymer resin are also suitably used, but not limited thereto.

The light emitting layer (2b) faces the light reflecting layer (2a) in the vicinity of the light source (2c), that is, at one end of the hollow light guide plate body (2), and becomes distal from the light source (2c). Along with this, it is smoothly curved toward the light reflection layer (2a), and finally arranged so as to be in contact with the light reflection layer (2a).

In the hollow light guide plate body (2) of the present invention,
Quantitatively controlling the light emission amount and the light reflection amount by adjusting the curvature of the curved portion of the transparent sheet (22) that constitutes the light emission layer (2b) and the size of each prism body (P). can do.

A light-transmissive sheet that constitutes the light emitting layer (2b)
(22) is the apex angle of each prism body that constitutes the convex portion of the concavo-convex surface of the continuous prism of the sheet as described in "Claim 2" of the present application.
(θ) has a high brightness when adjusted in the range of 70 to 110 °,
It is preferable in terms of high uniformity.

In the hollow light guide plate body (2) of the present invention, the linearly arranged light source (2c) may be a linear light source or a large number of point light sources arranged linearly. May be. In the present invention, it is preferable to use a linear light source, and examples thereof include a fluorescent lamp and a cold cathode discharge tube. The latter is more preferable in that it has a large amount of light per unit length and hardly generates heat. is there.

As the light reflecting layer (2a), a light reflecting sheet known in the art can be used as it is, but a reflecting layer having free electrons such as an aluminum foil or a thin film formed by a silver mirror reaction is accompanied by heat generation although it is weak. Therefore, a white plastic sheet (21) is preferably used. As a more preferable embodiment of the light reflecting layer (2a), the light reflecting sheet (21) and a large number of light-scattering dots (23) are provided as shown in "Claim 3" of the present application.
The light-scattering layer (2A) and the light-scattering dots (23)
Can be given to the light reflecting sheet, the density of which is adjusted based on the change in curvature of the light emitting layer (2b), which is very preferable from the viewpoint of high brightness and high uniformity.
The light-scattering layer is preferably prepared by mixing a transparent resin with a light-scattering inorganic substance to prepare a light-scattering ink, and printing the dot gradation pattern according to the curvature of the light-emitting layer. However, each light scattering dot itself in the dot gradation pattern may be formed by directly roughening the light reflecting sheet.

According to the present invention, as described in "Claim 4", two hollow light guide plate bodies (2) of the present invention are symmetrically arranged so that each light source is located at both ends. A hollow conductor formed by connecting the light-emitting layer (2b) and the light-reflecting layer (2a) of each hollow light guide plate body (2) so that the connecting lines are in contact with each other and the light-reflecting layers are connected so as to form the same plane. A light plate (1) can also be provided.

In the hollow light guide plate (1), the light diffusing layer (3) is outside the light emitting layer (2b) and is substantially parallel to the light reflecting layer (2a) as described in "Claim 5". It may be arranged in. As the light diffusion layer, those known in the art can be used as they are.

[0016]

According to the invention of "Claim 1" of the present application, the light source is
Most of the light emitted from (2c) is repeatedly reflected between the light reflecting layer (2a) arranged via the air layer (4) and the continuous prismatic surface of the light emitting layer (2b). A light guide is guided distally from the light source. Here, since both the straight-ahead light traveling in the horizontal direction from the light source (2c) and the reflected light pass through the air layer (4), the light is not absorbed during the passage and the light amount is not attenuated. Further, the light emitting layer (2b) is curved more smoothly as it goes farther from the light source (2c) to block the air layer (4), so that the straight light is always incident on one of the prism surfaces to be refracted and emitted. At the same time, the reflected light is also extended to the distal portion along with this curvature, and while the light emission near the light source is suppressed, the amount of light emitted from the light source to the distal portion is increased.

According to the invention of "Claim 2" of the present application,
Continuous prism Each prism body (P) that constitutes the convex part of the uneven surface
Since the apex angle (θ) is set to 70 to 110 °, the amount of light guided to the distal portion is increased and the light is further equalized.

According to the invention of "Claim 3" of the present application,
The light-reflecting layer (2a) is a light-scattering layer (2) composed of a light-reflecting sheet (21) and a large number of light-scattering dots (23) attached to the light-reflecting sheet.
A) and the distribution of the light-scattering dots (23) is
Since the density is adjusted based on the change in curvature of b), the light emitted from the light emitting layer (2b) will be more highly uniformized.

According to the invention of claim 4 of the present application,
Two of the hollow light guide plate bodies (2) according to any one of claims 1 to 3 are symmetrically arranged on the light reflection layer (2a) on the same plane, so that the light emitted in the vicinity of each light source is The amount of light emitted from each hollow light guide plate body (2) is appropriately mixed in the central portion while being suppressed, so that high uniformity and high brightness are obtained as a whole.

According to the invention of "Claim 5",
Since the light diffusing layer (3) is arranged outside the light emitting layer (2b) substantially parallel to the light reflecting layer (2a), glare on the light emitting surface is prevented while maintaining high brightness and high uniformity. The Rukoto.

[0021]

The present invention will be described in detail below with reference to the illustrated embodiments, but the present invention is not limited thereto. Example 1 FIG. 1 is a sectional configuration explanatory view of an example of a hollow light guide plate of the present invention. In the figure, a hollow light guide plate (1) includes two hollow light guide plate bodies (2) and (2) symmetrically arranged, and a light diffusing plate (3) provided above these hollow light guide plate bodies. ) And are mainly composed of.

Each hollow light guide plate body (2) is composed of a flat plate-like light reflecting layer (2a) and a light emitting layer which is smoothly curved in one direction and descends.
(2b), a linear light source (2c), and a lamp reflector (2d).

The light reflection layer (2a) is composed of a white plastic sheet (21), and in this example, it is composed of one sheet common to the two hollow light guide plate bodies (2).

Each light emitting layer (2b) is a translucent sheet made of polycarbonate, the outer surface is a smooth surface (2b1), and the inner surface has a large number of prisms (P) whose main axes are substantially perpendicular to the curved direction. It is composed of continuous prism concavo-convex surfaces (2b2) arranged in parallel. Each prism body on the concavo-convex surface of the continuous prism
(P) is set such that each apex angle (θ) is in the range of 70 to 110 ° as shown in FIG. The light emitting layer (2b) and the light reflecting layer (2a) are arranged via an air layer (4), and one end of the hollow light guide plate body faces substantially parallel to each other and the other end thereof. Then, the light emitting layer (2b) is in contact with the light reflecting layer (2a). And the air layer on the side opposite to each other substantially in parallel
The linear light source (2c) is arranged at the end of (4).

The linear light source (2c) is composed of two cold cathode discharge tubes (2c
1) (2c2) is used, and the two discharge tubes are arranged in a substantially vertical direction in the drawing, and these two discharge tubes are arranged so as to overlap each other in the vertical direction in the drawing.

The lamp reflector (2d) has a linear light source inside.
(2c1) and (2c2) are wrapped and provided from the end of the light reflecting layer (2a) to the end of the light emitting layer (2b).

The hollow light guide plate (1) is composed of each hollow light guide plate body (2).
(2) is each light emission layer (2b) (2b) on the common light reflection layer (2a)
Are arranged so that their contact ends can contact each other to form a boundary line (B).

The light diffusing plate (3) is the same as the one usually used in the art, and includes two hollow light guide plate bodies.
(2) It is arranged above (2) and substantially parallel to the light reflection layer (2a).

Hollow light guide plate (1) configured as described above
Is a linear light source (2c) arranged on a pair of opposing long sides as shown in the plan view of FIG. 3,
The size is X = 230 mm, Y = 145 mm in FIGS. 1 and 3,
It is set to t = 10 mm, but is not limited to this.

In the above structure, the apex angle of the prism body
Three kinds of hollow light guide plates (1A) (1B) (1C) having the same configuration except that (θ) is changed to 110 °, 90 °, and 70 °, respectively, were prepared, and each hollow light guide plate in FIG. The luminance (cd / m ² ) on the center line U line was measured from one linear light source at 5 mm intervals, and the results shown in the table of FIG. 4 were obtained. As a comparative example, a solid light guide plate having the same light emitting surface area in plan view as that of the embodiment, i) having a uniform thickness (t = 10 mm) [comparative example], ii) light emitting surface Is a concave surface that forms a part of the cylindrical surface and the opposite surface is a flat surface (maximum thickness t = 10 mm) [Comparative example], iii) Wedge type cross section (maximum thickness t = 10 mm) The symmetric symmetrically-connected ones (comparative examples) were prepared, and the brightness on each light emitting surface was measured in the same manner as in the example. The results are also shown in the table of FIG.

From the above results, the hollow light guide plate (1A) of the present invention
In each of (1B) and (1C), compared with Comparative Examples and
It can be seen that the mass is very small, the average luminance is large, and the uniformization over the entire light emitting surface is excellent.

Example 2 A hollow light guide plate (1) of Example 1 has the same structure as that of the light reflecting layer (2a) except that a light scattering layer (2A) is provided on the surface facing the light emitting layer. Therefore, the same members are designated by the same reference numerals and the description thereof will be omitted. Light scattering layer (2
A) is a light-scattering inorganic powder (for example, Si
A so-called dot gradation printing layer in which the light-scattering dots (23) are printed using an ink containing O ₂ ), and the density of the dot distribution is adjusted corresponding to the curvature change of the light-emitting layer (2b) at this time. It is composed of. In the dot gradation printing described above, the dot distribution becomes coarser on the light source side and becomes denser as it becomes distal from the light source, that is, according to the curvature.

By providing the light-scattering layer as described above, it was possible to obtain a hollow light guide plate in which the brightness on all emission surfaces was made more highly uniform.

[0034]

According to the present invention, it is possible to provide a side-light type light guide plate having a large light emission surface and having a large luminance and a uniform luminance. Furthermore, even if it is constructed in a large size, the light guide plate can be made extremely lightweight due to the hollow structure. In addition, in the case where the light scattering layer is formed by dot gradation printing, it is possible to achieve a higher degree of uniform brightness, and it is possible to provide a larger-sized sidelight type light guide plate of high quality.

[Brief description of drawings]

FIG. 1 is an explanatory view of a cross-sectional configuration of a hollow light guide plate of the present invention.

FIG. 2 is an enlarged schematic view of a main part of FIG.

FIG. 3 is an explanatory diagram of a plane configuration of FIG.

FIG. 4 is a table showing the luminance distribution on the light emitting surface of the hollow light guide plate of the present invention together with comparative examples.

[Explanation of symbols]

(1) (1A) (1B) (1C)… Hollow light guide plate (2)… Hollow light guide plate body (3)… Light diffusing plate (4)… Air layer (21)… White plastic sheet (22)… Translucent Sheet (2A) ... Light scattering layer (P) ... Prism body (2a) ... Light reflecting layer (2b) ... Light emitting layer (2c) ... Linear light source (2d) ... Lamp reflector (2b1) ... Smooth surface (2b2) )… Continuous prism uneven surface (2c1) (2c2)… Cold cathode discharge tube

[Procedure amendment]

[Submission date] March 31, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is an explanatory view of a horizontal cross-section of a hollow light guide plate of the present invention.

FIG. 2 is an enlarged schematic view of a main part of FIG.

FIG. 3 is an explanatory diagram of a plane configuration of FIG.

FIG. 4 is a chart showing a luminance distribution on a light emitting surface of a hollow light guide plate of the present invention together with a comparative example.

[Explanation of symbols] (1) (1A) (1B) (1C) ... Hollow light guide plate
(2) ... Hollow light guide plate body (3) ... Light diffusing plate (4) ... Air layer (21) ... White plastic sheet (22) ... Translucent sheet (2A) ... Light scattering layer (P) ... Prism body ( 2a) ... Light reflection layer (2b) ... Light emission layer (2c) ... Linear light source (2d) ... Lamp reflector (2b1) ... Smooth surface (2b2) ... Continuous prism uneven surface (2c1) (2c2) ... Cold cathode discharge tube

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Yusumi Taguchi 3-7-17 Nitta-cho, Niihama-shi, Ehime Nihon Chemitec Co., Ltd.

Claims (5)

[Claims] 1. A flat light-reflecting layer and a light-exiting layer that is smoothly curved in one axis direction, wherein the light-reflecting layer and the light-exiting layer face each other at one end of the curved axis and the light-exiting layer at the other end. The emission layer is arranged so as to be in contact with the light reflection layer via an air layer, and at the end of the air layer on the side where the light reflection layer and the light emission layer face each other, it is substantially perpendicular to the surface including the curved axis. The light-emitting layer has a smooth outer surface, and the inner surface facing the light-reflecting layer has a number of prisms parallel to each other with their main axes substantially perpendicular to the curved axes. A hollow light guide plate body, which is composed of a flexible light-transmissive sheet composed of concavo-convex surfaces of continuous prisms arranged in parallel with each other. 2. The hollow light guide plate body according to claim 1, wherein each prism body forming a convex portion of the concavo-convex surface of the continuous prism has an apex angle of 70 to 110 °. 3. The light-reflecting layer comprises a light-reflecting sheet and a light-scattering layer composed of a large number of light-scattering dots attached to the light-reflecting sheet, the light-scattering dots being based on a change in curvature of the light-emitting layer. The distribution density is adjusted to be 1 or 2.
The hollow light guide plate body described. 4. The hollow light guide plate body according to claim 1, wherein two of the hollow light guide plate bodies are symmetrically arranged so that each light source is located at both ends, and the light emitting layer of each hollow light guide plate body. And a connection line between the light reflection layer and the light reflection layer are in contact with each other, and the light reflection layers are connected so as to form the same plane. 5. The hollow light guide plate according to claim 4, wherein a light diffusing layer is arranged outside the light emitting layer substantially in parallel with the light reflecting layer.