JP2597297B2 - Surface lighting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface illumination device mainly used as a backlight of a liquid crystal display device.

[0002]

2. Description of the Related Art A conventional surface illuminating device comprises a light guide plate made of a transparent resin such as acrylic, a reflection plate provided on one surface of the light guide plate, and a diffusion plate provided on the other surface of the light guide plate. Plates are stacked and a light source is provided at the edge of the light guide plate.On the reflection plate side surface of the light guide plate, white spots are printed by screen printing to form a diffuse reflection surface. The light from the light source is irregularly reflected by the irregular reflection surface, reflected by the reflection plate, and diffused from the diffusion plate to illuminate, for example, a liquid crystal display device.

[0003]

However, when the irregular reflection surface is formed by screen-printing white spots on the light guide plate as described above, a diffuse reflection layer is formed by screen printing after the formation of the light guide plate. And the number of processing steps is increased, and a fluorescent lamp (CF.
When L) is used, the light of the light source may be absorbed by the irregular reflection layer, and therefore, the luminance of the light source (cd / cm)
² ) The light guide plate luminance (cd / cm ² ) is not sufficient for
Therefore, there is a problem that it is not possible to obtain sufficient illumination luminance while saving power.

A main object of the present invention is to provide a surface illuminating device capable of improving the light guide plate luminance with respect to the luminance of a light source while reducing the number of processing steps, and achieving sufficient illumination luminance while saving power. Another object of the present invention is to provide a surface illumination device that can improve the uniformity.

[0005]

According to a first aspect of the present invention, there is provided a light guide plate comprising a transparent resin, a reflection plate, and a light diffusion plate. In a surface lighting device in which a light source 5 composed of a fluorescent lamp is disposed in a portion, a plurality of convex portions 6a having a rhombic shape in a plan view are continuous in a chain on the surface of the light guide plate 1 on the reflecting plate side, and the side surface is continuously formed. The irregular reflection surface 6 formed by regularly arranging a plurality of ridges 6b having a bent plane portion to be bent at a predetermined pitch was formed simultaneously with the molding of the light guide plate 1.

According to a second aspect of the present invention, in the first aspect of the present invention, the light guide plate 1 is provided with a light diffusion surface 7 formed of a matte textured surface on the light diffusion plate side surface of the light guide plate 1. Formed at the same time.

[0007] Further, the invention according to claim 3 is based on claim 1.
In the invention described in (2), a large number of dot-shaped projections 11 having a function of condensing and diffusing lenses are regularly arranged on the surface of the light diffusing plate on the side opposite to the light guide plate.

According to a fourth aspect of the present invention, in any one of the first to third aspects of the present invention, the light source 5 disposed at the edge of the light guide plate 1 is connected to one side surface of the light guide plate 1 by one side. A single-lamp type fluorescent lamp connected to at least one adjacent side surface adjacent to the side surface.

[0009]

According to the first aspect of the present invention, a plurality of convex portions 6a having a rhombus shape in a plan view are continuously formed in a chain on the surface of the light guide plate 1 on the reflecting plate side, and a bent plane portion whose side surface is continuously bent. The irregular reflection surface 6, which is formed by regularly arranging a plurality of ridges 6b having a predetermined pitch at a predetermined pitch, is formed at the same time as the light guide plate 1 is formed. Since the irregular reflection surface 6 can be formed at the same time as the light guide plate 1 is formed, the number of processing steps can be reduced, the manufacturing cost can be reduced, and the irregular reflection surface 6 of the light guide plate 1 can be reduced. Is formed by regularly arranging a plurality of ridges 6b having a bent flat surface portion in which a plurality of convex portions 6a having a rhombic shape in a plan view are continuous in a chain, and a side surface is bent continuously at a predetermined pitch. The light is generated by these ridges 6b. 5 is efficiently diffusely reflected and the light is geometrically scattered, so that a desired average luminance can be obtained, and since there is no fine spot due to screen printing as in the conventional example. The light absorption can be reduced. Therefore, while using a fluorescent lamp as the light source 5, the luminance (cd / cm
^The light guide plate luminance (cd / cm ² ) with respect to ² ) can be improved. As a result, sufficient illumination luminance can be obtained while power saving can be performed.

According to the second aspect of the present invention, since the light diffusing surface 7 made of a matte textured surface is formed on the light diffusing plate side surface of the light guide plate 1, it is combined with the light diffusing plate laminated on the light guide plate. Thus, the diffusion effect can be improved, and the uniformity can be improved.

According to the third aspect of the present invention, since the dot-like projections 11 having a lens effect are provided on the light diffusing plate 3, the irregular reflection surface 6 of the light guiding plate 1 passes through the light guiding plate 1 on the light diffusing plate side. When passing through the light diffusing plate 3, the light that has been directed to the point is effectively condensed by the condensing lens function of the dot-like projections 11 and can be diffused by the diffusing function. However, the brightness can be further improved.
Therefore, when applied to a liquid crystal display, uniform visual recognition can be effectively performed over the entire surface.
The dot-like projections 11 are preferably hemispherical, so that focusing and diffusion can be performed more efficiently by the lens effect.

Furthermore, in the invention according to claim 4, a single-lamp type fluorescent lamp in which the light source 5 is connected to one side surface of the light guide plate 1 and at least one adjacent side surface adjacent to the one side surface, that is, L Because a U-shaped or U-shaped or frame-shaped fluorescent lamp is used, it is possible to improve the illumination brightness as compared to the case where the light source is provided only on one side of the light guide plate, and to provide the light source on each of the two opposite sides. In comparison, the number of lead wires can be reduced to two, and the wiring can be simplified.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The surface illumination device shown in FIGS. 1 and 2 is used for a backlight of a liquid crystal display device.
It is made of a transparent resin having excellent light transmittance, and has a thickness of, for example, 4 to
A light guide plate 1 having a thickness of 5 mm, a reflection plate 2 laminated on one side of the light guide plate 1, a light diffusion plate 3 laminated on the other side, and a Fresnel lens 4 laminated on the surface of the light diffusion plate 3 As shown in FIG. 2, the edge of the light guide plate 1 is continuous with three side surfaces, one side surface of the light guide plate 1 and two side surfaces adjacent to the one side surface. A single-light-type single light source 5 composed of a letter-shaped fluorescent lamp is provided.

On the surface of the light guide plate 1 on the reflection plate side, a plurality of convex portions 6a having a rhombus shape in a plan view are continuous in a chain, and a plurality of convex portions having a bent plane portion whose side surface is continuously bent. The irregularly reflecting surface 6 formed by regularly arranging the stripes 6b at a constant pitch, and the light diffusing surface 7 formed of a matte textured surface on the light diffusing plate side surface of the light guide plate 1 is provided. The light plate 1 is formed simultaneously with the molding.

The light guide plate 1 is formed by injection molding, and the irregular reflection surface 6 and the light diffusion surface 7 are
Formed simultaneously by the molding die, as an example, the cavity surface of one mold in the die, a plurality of concave portions having a diamond shape in a plan view are continuous in a chain, and the concave side surface is bent continuously. A plurality of concaves having a curved flat portion formed by etching using a mask having a planar pattern having the concaves, and a plurality of irregularities that make the cavity surface of the other mold sand-finished or etched. Form a part.

Then, an acrylic resin is injected into the cavities of these molds and molded into a plate shape. A plurality of convex portions 6a having a rhombus shape in a plan view are continuous on one side surface thereof. The irregular reflection surface 6 is formed by regularly arranging a plurality of ridges 6b having bent plane portions whose side surfaces are continuously bent at a constant pitch. The light diffusion surface 7 composed of the processed surface is formed.

Accordingly, since the irregular reflection surface 6 and the light diffusion surface 7 are formed simultaneously with the formation of the light guide plate 1 as described above, the processing of the light guide plate 1 can be facilitated, and the cost can be reduced accordingly.

The pattern of the ridges 6b forming the irregular reflection surface 6 has a rhombus shape in plan view as shown in FIG. Are formed with a plurality of protruding ridges 6b having a bent plane portion which is continuously bent, and the ridges 6b forming a continuous chain are formed at a constant pitch of 45 ° with respect to the side edge of the light guide plate 1. The height of each of the projections 6a is, for example, 50 μm.
It is preferable that the projecting surface area of each of the projections 6a increases as the distance from the light source 5 increases. In FIG. 1, reference numeral 8 denotes a light source reflection sheet, and in FIG. 2, reference numeral 9 denotes a lead wire of the light source.

Incidentally, in the embodiment shown in FIGS. 1 and 2, the light guide plate 1 is of a 2.5 inch type, and the reflection plate 2 has a thickness of 0.1 mm.
188 mm low-foaming film of white polyester manufactured by Toray Industries, Inc.
A 0.15 mm thick polyester film was used as the Fresnel lens 4, and a U-shaped fluorescent lamp (CFL) having a tube diameter of 3 mm was used as the light source 5. 5 mA, the light guide plate 1
The light source luminance of the first light emitting unit 5A provided on the first side
8,210 cd / cm ^2, and the light source luminance of the second light emitting unit 5B disposed on the second side surface adjacent to the first side surface is 30,530.
cd / cm ^2, and the light source luminance of the third light emitting unit 5C disposed on the third side surface adjacent to the second side surface is 30,660 cd / cm ^2.
When the luminance (cd / cm ² ) of the light guide plate was measured, the results shown in Table 1 were obtained.

The weather conditions at the time of measurement were as follows: temperature 2
The temperature was 4.5 ° C. and the humidity was 65%. In Table 1, A
ＣC are equal lines obtained by dividing the plane of the light guide plate 1 into four in the horizontal direction as shown in FIG. 4, and 〜 are equal lines obtained by dividing the plane of the light guide plate 1 into four in the vertical direction. Line-to-line and line-4
Five points of the two intersections and the intersection of the line B and the line are defined as luminance measurement points.

MIN / MAX is the ratio between the minimum luminance and the maximum luminance, and represents the degree of uniformity.

[0022]

[Table 1]

As is clear from Table 1, the light guide plate luminance is 11,950 cd / cm ² on average, and a high surface luminance can be obtained with respect to the average light source luminance of 29,800 cd / cm ^2. That is, a sufficient illumination luminance can be obtained while the conversion can be performed.

Next, a second embodiment shown in FIG. 5 will be described. This second embodiment is different from the first embodiment in that a large number of dot-like projections 11 having a condensing / diffusion lens function as shown in FIGS.
Is used in the second diffusion plate 10 provided regularly.

That is, the second embodiment shown in FIG.
The first light diffusion plate 3 is laminated on the light guide plate 1 and the second light diffusion plate 10 is laminated on the first light diffusion plate 3 as in the first embodiment shown in FIG. The diffusion plate 3
A light diffusion plate made of a known polyester resin, which is provided with matte-like irregularities on the opposite surface of the light guide plate 1 and has a milky white color, is used.
Is a resin sheet made of, for example, a polycarbonate resin or a polyester resin, and a large number of dot-like projections 11 having a function of condensing and diffusing lenses are regularly provided on the surface of the resin sheet opposite to the light guide plate 1. . The dot-like projections 11 are formed by embossing using, for example, an embossing roll. In the embodiment shown in FIGS. 5 to 7, the dot-like projections 11 are formed into a hemispherical shape having a diameter of about 40 μm.
1 were arranged regularly in a staggered manner as shown in FIG. 7 at a pitch of 40 μm.

However, by using the second light diffusing plate 10 configured as described above, the brightness was further improved as compared with the first embodiment.

This is because the dot-like projections 11 are provided. The reason is that these projections 11 act as lenses and have a structure in which a number of small lenses are arranged. It is considered that the transmitted light can be efficiently condensed by the lens effect, and the condensed light can be efficiently diffused in each dot-shaped projection 11.

Although the dot-like projections 11 are hemispherical, they may be truncated pyramids, truncated cones, or cylindrical prisms, examples of which are shown in FIGS. 8 and 9.
8 and 9, the distance between the facing surfaces is a maximum of, for example, 40.
7 μm, a truncated hexagonal pyramid with each side having an inclination angle of about 35 degrees, and a circular concave portion 12 having a diameter of 7.5 μm formed at the center of the top surface, similar to the embodiment shown in FIG. They are regularly arranged in a staggered pattern. Also in this case, the luminance can be improved as in the embodiment shown in FIGS. 5 to 7, and by forming the circular concave portion 12, the luminance can be improved as compared with the case where the circular concave portion 12 is not formed.

In the above embodiment, the first light diffusing plate 3 is used and the second light diffusing plate 10 is laminated on the first light diffusing plate 3, but the first light diffusing plate 3 is not used. May be.

Further, since the light source 5 uses a single U-shaped fluorescent lamp, the effect of improving the luminance as shown in Table 1 can be obtained in combination with the configuration of the irregular reflection surface 6 of the light guide plate 1. However, a single-lamp type single fluorescent lamp having an L-shape or a frame shape, that is, a frame shape having light-emitting portions opposed to four side surfaces of the light guide plate 1 may be used.

As described above, when a single-lamp type single fluorescent lamp having a U-shape, an L-shape, or a frame shape is used, the number of the lead wires 9 can be reduced to two while the brightness is improved. The number of lead wires can be reduced and the wiring can be simplified as compared with the required conventional two-lamp system.

The light guide plate 1 is a small one of a 2.5-inch type. However, the light guide plate type is not particularly limited. Can be

Further, since the light diffusing surface 7 made of a textured uneven surface is formed on the surface of the light guide plate 1 on the side of the diffusion plate, the degree of uniformity of the light guide plate 1 can be improved as shown in Table 1. Although the uniformity of the entire apparatus can be improved in combination with the diffusion effect of the third embodiment, the diffusion surface 7 may be omitted.

[0034]

According to the first aspect of the present invention, the light guide plate 1 is provided.
A plurality of ridges 6a having a rhombic shape in a plan view are continuous in a chain, and a plurality of ridges 6b having a bent plane portion whose side surface is continuously bent are regularly arranged at a predetermined pitch on the reflector side surface of the device. The irregular reflection surface 6 is formed at the same time when the light guide plate 1 is formed. Therefore, unlike the conventional example, it is not necessary to screen-print minute spots to form the irregular reflection surface.
Since the irregular reflection surface 6 can be formed at the same time as the molding, the number of processing steps can be reduced, and the manufacturing cost can be reduced.

Further, the irregular reflection surface 6 of the light guide plate 1 has a plurality of projections 6a having a rhombic shape in a plan view and a plurality of projections 6b having a bent plane portion whose side surface is continuously bent in a chain shape. Are arranged regularly at a predetermined pitch, so that the light from the light source 5 can be efficiently irregularly reflected by these ridges 6b, and the light can be geometrically scattered. Average brightness is obtained, and
Since there are no fine spots due to screen printing as in the conventional example, light can be less absorbed, and therefore,
While using a fluorescent lamp as the light source 5, the light guide plate luminance (cd / cm ² ) with respect to the luminance (cd / cm ² ) of the light source 5 can be improved. As a result, sufficient illumination luminance can be achieved while saving power. Is obtained.

According to the second aspect of the present invention, since the diffusion surface 7 made of the textured surface is formed on the surface of the light guide plate 1 on the side of the diffusion plate, it is combined with the light diffusion plate laminated on the light guide plate. Thus, the diffusion effect can be improved, and the uniformity can be improved.

According to the third aspect of the present invention, since the dot-like projections 11 having a lens effect are provided on the light diffusing plate 3, the light diffusing plate 6 passes through the light guiding plate 1 on the irregular reflection surface 6 of the light guiding plate 1. When passing through the light diffusing plate 3, the light that has been directed to the point is effectively condensed by the condensing lens function of the dot-like projections 11 and can be diffused by the diffusing function. However, the brightness can be further improved.
Therefore, when applied to a liquid crystal display, uniform visual recognition can be effectively performed over the entire surface.
The dot-like projections 11 are preferably hemispherical, so that focusing and diffusion can be performed more efficiently by the lens effect.

Further, according to the fourth aspect of the present invention, a single-lamp type fluorescent lamp in which the light source 5 is connected to one side surface of the light guide plate 1 and at least one adjacent side surface adjacent to the one side surface, that is, L Because a U-shaped or U-shaped or frame-shaped fluorescent lamp is used, it is possible to improve the illumination brightness as compared to the case where the light source is provided only on one side of the light guide plate, and to provide the light source on each of the two opposite sides. In comparison, the number of lead wires can be reduced to two, and the wiring can be simplified.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first embodiment of the present invention.

FIG. 2 is a plan view omitting a light source reflection cover.

FIG. 3 is a pattern diagram showing a dot-like unevenness processing pattern of a diffuse reflection plate.

FIG. 4 is a plan view of the light guide plate showing luminance measurement points.

FIG. 5 is a sectional view showing a second embodiment of the present invention.

FIG. 6 is a partially enlarged cross-sectional view of a second light diffusion plate.

FIG. 7 is a pattern diagram of dot-like projections on a second light diffusion plate.

FIG. 8 is a partially enlarged sectional view showing another example of the second light diffusion plate.

FIG. 9 is a pattern diagram of dot-like protrusions in the second light diffusion plate shown in FIG.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 light guide plate 2 reflection plate 3 light diffusion plate 5 light source 6 diffuse reflection surface 7 light diffusion surface 11 dot projection

Claims (4)

(57) [Claims] A light guide plate (1) made of a transparent resin ;
A reflector (2) laminated on one side of the light plate (1) and a light guide
A light diffusing plate (3) laminated on the other surface of the light plate (1), wherein a light source (5) composed of a fluorescent lamp is disposed at an edge of the light guide plate (1); A plurality of projections (6a) having a rhombus shape in a plan view are continuously formed in a chain on the surface of the light guide plate (1) on the reflection plate side.
Having a bent plane portion whose side surface is continuously bent
Are regularly arranged at predetermined pitches.
The diffused reflection surface (6) is formed simultaneously with the formation of the light guide plate (1) . 2. A satin finish is formed on the surface of the light guide plate (1) on the light diffusion plate side.
The light diffusing surface (7) composed of a textured surface is provided on the light guide plate (1).
2. The surface lighting device according to claim 1, wherein the surface lighting device is formed at the same time as the molding.
Place. 3. A light condensing / expanding surface on a surface of the light diffusing plate on a side opposite to the light guide plate.
Numerous dot-shaped projections (11) with scattering lens function
The surface lighting device according to claim 1, wherein the surface lighting device is arranged in a parallel manner. 4. A light source disposed at an edge of a light guide plate (1).
(5) is one side of the light guide plate (1) and one side thereof.
One continuous with at least one adjacent side
The surface according to claim 1, wherein the surface is a fluorescent lamp of a lamp type.
Lighting equipment.