JPH10206645A - Surface emitting device - Google Patents

Abstract

(57) [Summary] [Object] To provide a surface light emitting device capable of obtaining high luminance surface light emission with little luminance loss. A linear light source is arranged on a side surface of a transparent light guide plate, and a dot diameter of 140 μm to 290 μm is used on the light output surface of the light guide plate using an ink containing titanium dioxide and nylon beads in a copolymer of styrene and methyl methacrylate. , Number of lines 65
A light emitting layer having a gradation pattern designed to have a line and area density of 12 to 55% is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin and illuminated illumination, and a thin and light edge type surface light emitting device suitable for a laptop personal computer, a word processor, a backlight of a liquid crystal TV, and the like.

[0002]

2. Description of the Related Art Conventionally, as a surface light emitting device of the edge light type, a line light source 2 is disposed on a side surface of a transparent light guide plate 1, and a line light source 2 is disposed on a surface opposite to a light exit surface of the light guide plate 1. Also, the light scattering layer 6 is provided in a gradation pattern such that the area ratio is increased at a position distant from the linear light source 2, and a diffusion sheet 7 is further disposed on the light exit surface of the light guide plate 1 (see FIG. 3). .

The light scattering layer 6 scatters light guided from the line light source 2 into the light guide plate 1 and reflects a part of the light toward the light emitting surface side of the light guide plate 1 at an angle at which light can be easily emitted. By using the gradation pattern, light is uniformly distributed on the light exit surface of the light guide plate 1.

The diffusion sheet 7 diffuses the light from the light guide plate 1 to reduce the difference between the brightness near the upper part of each dot portion on the light exit surface of the light guide plate 1 and the brightness of the surrounding dot-free portion. The size is reduced so that light emission near the upper part of the dot portion is not noticeable.

[0005]

However, in the above-described surface light emitting device, all of the light that is scattered and reflected by the light scattering layer and travels toward the light emitting surface of the light guide plate travels inside the light guide plate. The light attenuated while traveling in the light plate, and the brightness on the light emitting surface was lost correspondingly.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems, and to provide a surface light emitting device capable of obtaining high luminance surface light emission with little luminance loss.

[0007]

In order to achieve the above object, a surface light emitting device according to the present invention has a linear light source disposed on a side surface of a transparent light guide plate, and has a gradation pattern on a light exit surface of the light guide plate. It was configured such that a layer was provided.

In the above structure, the gradation pattern of the light emitting layer is constituted by dots having a size of less than 635 μm and the number of lines is 40 or more.

Further, in the above configuration, the back reflection layer is arranged on the surface of the light guide plate opposite to the light exit surface.

Further, in the above configuration, the light-emitting surface of the light guide plate is configured to be uneven.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a sectional view showing one embodiment of the surface light emitting device according to the present invention, and FIG. 2 is a sectional view showing another embodiment of the surface light emitting device according to the present invention. In the figure, 1 is a light guide plate, 2 is a line light source, 3 is a light emitting layer, 4 is a back reflection layer, 5 is a side reflection layer, and 6 is a light scattering layer.

The surface light emitting device shown in FIG. 1 has a transparent light guide plate 1 in which a line light source 2 is arranged on a side surface, and a light emitting surface of the light guide plate 1 provided with an easy light emitting layer 3 having a gradation pattern. is there.

The light guide plate 1 has a thickness of 0.5 to 5.0.
A rectangular plate of about mm is preferred. The cross-sectional shape of the light guide plate 1 may be a flat plate having a constant thickness, or an inclined surface portion may be formed on the side opposite to the light exit surface so as to become thinner as the distance from the line light source increases. Further, the light guide plate 1 may be curved. Examples of the material of the light guide plate 1 include methacrylate polymers or copolymers such as polymethylpentene resin, hydroxyethyl methacrylate and polymethyl methacrylate, acrylate polymer or copolymer, acetyl cellulose, acetyl Transparent cellulose resins such as butylcellulose, polycarbonate resins, polystyrene resins, acrylic styrene resins, transparent vinyl chloride resins such as polyvinyl chloride, copolymers of vinyl chloride and methacrylate, ethylene-vinyl acetate copolymer, etc. Transparent resin or glass can be used.

As the line light source 2, a cathode ray tube such as a cold cathode ray tube or a hot cathode ray tube having a diameter of about 2 to 3 mm is used. The shape of the linear light source 2 may be linear, L-shaped over two adjacent sides, U-shaped over three adjacent sides, or the like. Further, a plurality of line light sources 2 may be arranged.

The easy light emitting layer 3 scatters light guided into the light guide plate 1 from the linear light source 2 on the light emitting surface, and emits most of the scattered light without advancing in the light guide plate 1 (hereinafter, referred to as “light scattered light”). (Referred to as scattered refraction). Therefore,
The amount of light emitted from the light emitting layer 3 due to scattering and refraction does not attenuate by the amount that does not proceed in the light guide plate 1 after scattering, so that the brightness of the surface light emitting device can be improved. In addition, the easy light emitting layer 3
Is formed in a gradation pattern based on a tendency that the area ratio at a position distant from the line light source 2 is larger than the area ratio near the line light source 2, thereby uniformly distributing the emitted light. In order to obtain more uniform light emission, pattern correction such as partially increasing or decreasing the area ratio is performed as necessary in addition to the above basic tendency. For example, in the case where the brightness decreases near both ends due to the properties of the line light source 2, the area ratio of the easy light emitting layer 3 near both ends of the line light source 2 is corrected so as to be larger than the surrounding area. In order to change the area ratio of the easy-to-light-emitting layer 3, the easy-light-emitting layer 3 is constituted by arbitrary dots, and the dot size is changed or the number of dots is changed depending on the position. The shape of the dot is not particularly limited, and may be an arbitrary shape such as a round dot, a square dot, and a chain dot. Also,
Instead of dots, they may be formed in stripes. Examples of the method for forming the light emitting layer 3 include a printing method such as gravure printing and screen printing using a matte ink, a transfer method, and a molding simultaneous transfer method. As the matte ink, an ink containing silica, titanium dioxide, nylon beads, calcium carbonate, or the like is used.

The gradation pattern of the light emitting layer 3 is composed of dots having a size of less than 635 μm and having a line number of 4
It is preferable that the number of lines be equal to or more than zero. By setting the gradation pattern in such a range, it is possible to reduce the difference between the luminance near each dot on the light emitting surface side of the light guide plate 1 and the luminance of the surrounding dot-free portion, and without using a diffusion sheet. Light emission can be made inconspicuous. Moreover, since the structure without the diffusion sheet is made possible, the luminance of the surface light emitting device can be further improved. This is because the diffusion sheet has a problem that a part of the light emitted from the light exit surface side of the light guide plate 1 is reflected back to the light guide plate 1 side, and the brightness is reduced by that amount. Note that a diffusion sheet may be used even when a gradation pattern in the above numerical range is formed.

The thickness of the light emitting layer 3 is preferably 2 μm or less. If the thickness is too large, light is absorbed in the easy light emitting layer 3 or the amount of light reflected back to the light guide plate 1 increases, so that the amount of light emitted from the easy light emitting layer 3 decreases. .

Further, as shown in FIG. 2, a back reflection layer 4 may be disposed on the surface of the light guide plate 1 opposite to the light exit surface. The back reflection layer 4 reflects light emitted from the surface of the light guide plate 1 opposite to the light exit surface toward the light guide plate 1 so that the light can be used efficiently. As a material of the back reflection layer 4, silica,
An ink containing titanium dioxide, mica, calcium carbonate, resin hollow beads, white pigment, silicon powder, or the like is preferably printed or applied. In addition, a resin sheet containing a white pigment such as a white polyethylene terephthalate film can be used.

Further, the side reflection layer 5 may be disposed on the side of the light guide plate 1 where the line light source 2 is not disposed (see FIG. 2). The side reflection layer 5 reflects the light emitted from the side surface of the light guide plate 1 toward the light guide plate 1 so that the light can be used efficiently. As the material of the side reflection layer 5, the same material as that of the back reflection layer 4 may be used.

The light exit surface of the light guide plate 1 may be made uneven (not shown). In the case where the surface light emitting device has the above-described structure without the diffusion sheet, light interference generated by close contact between the light guide plate 1 and a smooth film such as a lens sheet or a housing disposed on the light exit surface side thereof, so-called Newton's. This is because the ring can be prevented by making the light exit surface of the light guide plate 1 uneven. The unevenness of the light emitting surface includes a matte surface, a wave surface, a prism surface, and the like.

Further, a light source reflection layer may be disposed so as to cover the line light source 2 on the side opposite to the light guide plate 1 (not shown). The light source reflection layer reflects light from the side opposite to the light guide plate 1 of the linear light source 2 toward the light guide plate 2 so that the light can be used efficiently. As the material of the light source reflection layer, the back reflection layer 4
It is good to use the same thing as. Note that the distance between the linear light source 2 and the light source reflection layer is preferably kept uniform by interposing a spacer between them.

The back reflection layer 4 or the side reflection layer 5
Can be replaced with a case for a surface light emitting device whose inner surface is painted with a white paint.

[0023]

【Example】

Example 1 On a base sheet made of a polyethylene terephthalate film, an ink containing silica in a copolymer of vinyl chloride and methyl methacrylate was used, and the dot diameter was 80 μm to 1 μm.
Gravure printing was performed using a gravure intaglio designed to have a line number of 60 μm, a number of lines of 150, and an area density of 20 to 80%.

Next, a flat plate made of polymethyl methacrylate resin having a length of 260 mm, a width of 195 mm and a thickness of 4 mm is used as a light guide plate, and the above-mentioned transfer sheet is superimposed on the light exit surface so that the base sheet side is the outer surface. By applying heat and pressure from the base sheet side of the transfer sheet using a roll transfer machine equipped with silicon rubber, the easy light emitting layer was adhered to the light emitting surface of the light guide plate, and the base sheet was peeled off after cooling.

Further, a tube length of 270 m is provided on one side of the light guide plate.
A cold cathode ray tube having a diameter of 2.8 mm and a diameter of 2.8 mm was arranged as a line light source.

A film containing a white pigment (E60L, 180 manufactured by Toray Industries, Inc.) is provided on the surface of the light guide plate opposite to the light exit surface and on the side surface of the light guide plate on which the linear light source is not arranged.
μm) was disposed as a back reflection layer to obtain a surface emitting device.

In this surface light-emitting device, light is emitted by scattering and refraction in the easy-to-emit light layer, so that a luminance loss is small and high-luminance surface light is obtained.

Example 2 An ink containing titanium dioxide and nylon beads in a copolymer of styrene and methyl methacrylate was used on a base sheet made of a polyethylene terephthalate film. The dot diameter was 140 μm to 290 μm, and the number of lines was 65. Gravure printing was performed using a gravure intaglio designed to have a line and area density of 12 to 55%, thereby providing an easy light-emitting layer to obtain a transfer sheet.

Next, the transfer sheet is fed into a molding die composed of a movable die and a fixed die, and after the molding die is closed, a polymethyl methacrylate resin in a molten state is passed through a gate provided in the fixed die. Into the cavity,
A light guide plate having a wedge-shaped cross section of 0 mm, 195 mm in width, and 2.8 to 1.5 mm in thickness is obtained, and a light guide plate having wavy irregularities on a surface serving as a light output surface is obtained, and at the same time, an easy light output layer is provided on the light output surface of the light guide plate. After bonding and cooling, the molding die was opened, the light guide plate was taken out, and the base sheet was peeled off.

On one side of the light guide plate, a tube length of 270 m is provided.
A cold cathode ray tube having a diameter of 2.8 mm and a diameter of 2.8 mm was arranged as a line light source.

A film containing a white pigment (E60L, 180 manufactured by Toray Industries, Inc.) is provided on the surface of the light guide plate opposite to the light exit surface and on the side surface of the light guide plate where no linear light source is arranged.
μm) was disposed as a back reflection layer to obtain a surface emitting device.

In this surface light emitting device, light is emitted by scattering and refraction in the easy-to-emit light layer, so that a surface light emission with high luminance and a small luminance loss was obtained.

[0033]

The surface light emitting device of the present invention has the following effects because the linear light source is disposed on the side surface of the transparent light guide plate and the easy light emitting layer having the gradation pattern is provided on the light emitting surface of the light guide plate. Play.

That is, the light-emitting layer formed on the light-emitting surface scatters light guided into the light guide plate from the linear light source, and diffuses and refracts most of the scattered light without leaving the light guide plate. Because of the function, the amount of light emitted from the easy-to-light-emitting layer was not attenuated by the amount that it did not progress in the light guide plate after scattering, and high-luminance surface light was obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of a surface emitting device according to the present invention.

FIG. 2 is a sectional view showing another embodiment of the surface emitting device according to the present invention.

FIG. 3 is a cross-sectional view showing a conventional surface emitting device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 light guide plate 2 line light source 3 easy light emitting layer 4 back reflection layer 5 side reflection layer 6 light scattering layer 7 diffusion sheet

Claims (4)

[Claims] 1. A surface light emitting device comprising: a linear light source disposed on a side surface of a transparent light guide plate; and a light emitting layer having a gradation pattern provided on a light exit surface of the light guide plate. 2. A gradation pattern of an easy light emitting layer,
The surface light emitting device according to claim 1, wherein the surface light emitting device is formed of dots having a size of less than 635 µm and has a line number of 40 or more. 3. The surface light emitting device according to claim 1, wherein a back reflection layer is disposed on a surface of the light guide plate opposite to the light exit surface. 4. The light guide plate according to claim 1, wherein the light exit surface of the light guide plate is uneven.
4. The surface-emitting device according to any one of claims 1 to 3.