JP2002025323A - Light guide plate and surface luminescence device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light guide plate with low cost which can uniformly distribute the light from a light source to whole part of a luminescent surface by itself, prevent the luminescent surface distant from the light source from lowering of brightness, and irradiate mainly in the direction of normal line of luminescent surface, and to provide a surface luminescence device using a light guide plate. SOLUTION: In order to guide the light from a light source 2, 7 insides, through a light guide surface 6 at its side, and in order to make the light disperse at luminescent surface 12, the light guide plate 1 made of a translucent material is formed into plate shape A reflection shaping part 5, comprising a light incident surface 8 approximately parallel with the light guide plate 6, at least one reflection surface 9 with an angle of inclination reflecting the light component L1 entered with an angle bigger than critical angle β, and a light emitting surface 10 approximately parallel with the light guide surface 6, is formed on a surface opposite to the luminescent surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light guide plate having a light emitting surface having a predetermined area and a surface light emitting device using the same, and more particularly to a technique suitable for illuminating a liquid crystal display device or the like from behind. .

[0002]

2. Description of the Related Art When illuminating a liquid crystal display portion or the like having a predetermined area from the back, one of the first considerations is that light generated from a light source is uniformly distributed on all portions of a light emitting surface having a predetermined area. It is mentioned. Then, the luminance of the light emitting surface separated from the light source is not reduced as much as possible.

As described above, many proposals have been made in order to minimize the luminance of the light emitting surface which is uniformly distributed on all the light emitting surfaces and which is separated from the light source. No. 316377, JP-A-2000-89031
As disclosed in the publication, a large number of concave portions for reflection are formed on a surface facing the light emitting surface of the light guide plate, and the light from the light source is directed to the light emitting surface by reflecting at these concave portions, By increasing the formation density of the recesses as the distance from the light source increases, the luminance does not decrease even when the distance from the light source increases, and furthermore, the slope of the light guide plate decreases in thickness as the distance from the light introduction surface decreases. , And guides the guided light to a distant place.

On the other hand, according to Japanese Patent Application Laid-Open No. H11-126030, there is proposed a light guide plate in which a prism having a triangular cross section is formed in place of the above concave portion. FIG. 11 is a cross-sectional view of a surface light emitting device using a light guide plate 101 disclosed in Japanese Patent Application Laid-Open No. H11-126030. In FIG. 11, a line light source 2 such as a fluorescent lamp or a high-luminance A point light source such as a white light emitting diode 7 is disposed on the side of the light guide plate 101 formed of a material having high light transmittance, and light from these light sources is guided from the light guide surface 106 in the surface direction of the light guide plate 101. The light is emitted from the light emitting surface 112 of the light guide plate 101, and is scattered by the scattering sheet 21 provided side by side.

A large number of prism-like reflecting surfaces 109 are formed on an opposite surface of the light guide plate 101 opposite to the light emitting surface 112, and light is incident on the reflecting surface 109 from the light source in the direction of the arrow. Light-emitting surface 1 that reflects light
12, while the light emitting surface 112 is formed so as to form more reflective surfaces 109 as the distance from the light source increases.
Are configured to have uniform brightness.

[0006] The surface light emitting device thus configured has been partially put to practical use as a backlight for the liquid crystal display unit 22.

The above light guide plate was measured by a self-made light quantity measuring device shown in FIG. This light quantity measuring device includes a base 20.
The rotating table 210 is manually rotatable in the direction of the arrow on the rotating table 210, and the fluorescent lamp 2 provided with the reflecting plate 3 is mounted on the rotating table 21.
In addition to fixing the light guide plate 101 to the fluorescent lamp 2, the light guide plate 101 passes through the center of rotation and guides the light to the fluorescent lamp 2 on the outer peripheral surface of the turntable 201. It is placed so that the surfaces 106 face each other.

The base 200 has a sensor 2 for measuring luminance.
The sensor 202 measures the brightness of the light emitted from the light emitting surface 112 of the light guide plate 101 by this sensor 202, sends the measurement result to a measuring device 210 built in the printer, and connects to output from the printer. It was done.

With the above-described light quantity measuring device, a luminance measurement result plotted for each angle shown in FIG. 13 was obtained.

According to the measurement results shown in FIG. 13, the amount of light in the normal direction at an angle of zero degrees perpendicular to the light emitting surface 112 is poor, the peak is directed in the direction of an angle of 30 degrees, and a part of the peak is directed to the opposite surface side. Was measured. in this way,
Since the peak value is not directed in the normal direction, when used as a backlight for illuminating the liquid crystal display unit 22, the amount of light from the front is insufficient.

Therefore, two prism films for increasing the brightness, sold under the trade name “BEF II” by Sumitomo 3M, are placed between the liquid crystal display section 22 and the scattering sheet 21. A surface light emitting device provided with prisms so that the peaks are orthogonal to each other has been put to practical use. According to the surface light emitting device, since the light from the light source can be mainly emitted in the normal direction perpendicular to the light emitting surface 112, it is used particularly as a backlight of a color liquid crystal display device.

[0012] This prism film for increasing brightness forms a mountain-shaped prism from an acrylic resin on a polyester film layer, and has an effect of converging irradiated light to a viewing angle of up to 70 degrees. Have been.

[0013]

However, the above-mentioned prism film for increasing the brightness is considerably expensive as compared with the light guide plate. Further, since it is necessary to provide two prism films between the liquid crystal display unit 22 and the scattering sheet 21, the dimension in the thickness direction increases. In addition, since an extra step for laying the prism film is added in the manufacturing process, there is a problem that the cost is further increased.

Accordingly, the present invention has been made in view of the above-mentioned problems, and it is possible to uniformly distribute light from a light source to all portions of a light-emitting surface using only a light guide plate, and to provide light emitted from a light source separated from the light source. It is an object of the present invention to provide an inexpensive light guide plate capable of preventing the luminance of a surface from being lowered and emitting light mainly in a normal direction of a light emitting surface, and a surface light emitting device using the same.

[0015]

Means for Solving the Problems The above-mentioned problems are solved,
In order to achieve the object, according to the present invention, there is provided a light guide plate formed of a light transmissive material for guiding light from a light source from a side light introducing surface to an inside and emitting light from a light emitting surface. A light incident surface substantially parallel to the light introducing surface, at least one reflecting surface having an inclination angle for reflecting incident light incident at a critical angle or more determined from the light transmitting material, and the light introducing surface And a light-emitting surface substantially parallel to the light-emitting surface are formed at predetermined intervals on a surface facing the light-emitting surface.

Further, the predetermined interval is set so as to reflect the incident light using at least two of the reflection-shaped portions.

[0017] Further, the distance between the opposing surface and the light emitting surface is reduced as the distance from the light introducing surface increases.

Further, the light source is a point light source, and the reflection-shaped portion is formed with a groove having both the light entrance surface and the light exit surface on both inner wall surfaces, and has a ripple centered on the point light source. And the light source is the linear light source, and is formed in a straight line parallel to the linear light source while interposing a groove having both the light entrance surface and the light exit surface as both inner wall surfaces. It is characterized by.

Further, the reflecting shape portion is characterized in that the light incident surface and the light emitting surface are formed on an outer peripheral surface of a cylindrical shape, and the reflecting surface is formed in a conical or spherical shape at a head. .

Further, the reflection-shaped portion is formed such that the light entrance surface and the light exit surface are formed on a cylindrical outer peripheral surface, and the light entrance surface and the light exit surface are formed in a bottomed hole at the center. Further, the reflection surface is formed in a conical or spherical shape over the bottomed hole and the outer peripheral surface.

Further, the light emitting surface is subjected to a light scattering process.

Also, a light-transmitting material is formed from a light-transmitting material to guide light from the light source into the inside from the side light introduction surface and emit the light from the light-emitting surface. A reflection shape portion formed by at least one reflection surface having an inclination angle for reflecting incident light incident at a critical angle or more determined from the light transmitting material, and a light exit surface substantially parallel to the light introduction surface; A light guide plate formed at a predetermined interval on a surface facing the light emitting surface, a light scattering sheet disposed adjacent to the light guide plate in front of the light emitting surface side, and further forward of the light scattering sheet. And a display unit disposed in the device.

A light-transmitting material is formed from a light-transmitting material to guide light from the light source into the inside from the lateral light-introducing surface and emit the light from the light-emitting surface, and a light-incoming surface substantially parallel to the light-introducing surface. ,
At least one reflection surface having an inclination angle for reflecting incident light incident at a critical angle or more determined from the light transmitting material, and a reflection shape portion formed from a light exit surface substantially parallel to the light introduction surface. A light guide plate formed at a predetermined interval on a surface facing the light emitting surface, and performing a light scattering process on a light emitting surface of the light guide plate, and a display unit disposed further forward of the light guide plate. It is characterized by having.

[0024]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1A is a plan view of a surface light-emitting device using a light guide plate of the first embodiment using a line light source, and FIG. 1B is a plan view using a light guide plate of the second embodiment using a point light source. It is a top view of a light emitting device. In FIG. 1, a case body for holding each component at the illustrated position is omitted.

First, in FIG. 1A, the light guide plate 1 is
For example, in order to use it as a backlight for a liquid crystal display unit having no self-luminous ability, it is formed in a plate shape having the same light emitting surface as the liquid crystal display unit. The light guide plate 1 is formed by mechanical grinding or resin injection molding from a light transmissive material such as optical glass, acrylic resin, or polycarbonate resin.

On the side surface of the light guide plate 1, a fluorescent lamp 2 having a reflection plate 3 as a linear light source is disposed in close proximity.
The light guide plate 1 is configured to guide light from the side light introduction surface 6 to the inside of the light guide plate 1.

In FIG. 1B, a high-intensity light emitting diode 7 having a reflector 3 as a point light source is provided on a side surface of the light guide plate 1. This light emitting diode 7
As shown in the figure, the light guide plate 1 is arranged at the center of a light introducing surface 6 formed in a semicircular concave shape on the side surface of the light guide plate 1, and is configured to guide light inside the light guide plate 1.

Next, FIG. 2A shows FIGS. 1A and 1B.
3 is a sectional view taken along line XX in FIG. FIG. 1 (a),
2B, the light introducing surface 6 has an area for introducing all the light emitted from the fluorescent lamp 2 or the light emitting diode 7, and the light introducing surface 6 has a light emitting surface 12. In the case of manufacturing from the above-mentioned injection mold, care is taken not to form an under part, but the present invention is not limited to this, and a concave arc shape shown by a broken line is used. May be.

The light scattering sheet 21 is provided on the light emitting surface 12.
, And a liquid crystal display unit 22 is further provided thereon.

A light incident surface 8 substantially parallel to the light introducing surface 6 formed from a plane substantially perpendicular to the light emitting surface 12;
A reflection surface 9 having an inclination angle for totally reflecting incident light incident at a critical angle or more determined from the light transmitting material;
Reflection-shaped portions 5 formed of a light-introducing surface 6 and a light-emitting surface 10 substantially parallel to each other are formed at predetermined intervals on a surface facing the light-emitting surface. In addition, between each of the reflection shape portions 5, a groove portion 4 is provided.
Are formed. The above-mentioned inclination angle is determined from the material forming the light guide plate 1.

FIG. 3 is a partially enlarged view of FIG. 2A, showing a case where the above-mentioned two reflection-shaped portions 5 are formed. The same reference numerals are given to the components already described and the description is omitted, and the reflection surface 9 has an inclination angle for totally reflecting the incident light incident at a critical angle β or more determined from the light transmitting material. is set to θ. In addition, the reflection shape part 5 and the groove part 4 are formed in a straight line parallel to the light guide surface 6 in the case shown in FIG. In the case shown in FIG. 1B, the light emitting diode 7 is formed in a ripple shape with the light emitting diode 7 as a center.

In FIG. 3, the light component L1 introduced from the fluorescent light source 2 or the light emitting diode 7 as the light source via the light guiding surface 6 is first refracted from the light emitting surface 10 and emitted.
After being introduced into the reflection shape part 5 from the first light entrance surface 8,
The light is reflected by the reflecting surface 9 and emitted in the direction of the normal to the light emitting surface 12. Of the light component L1, the light component introduced at a critical angle β or more with respect to the normal 11 of the reflection surface 9 is totally reflected, so that the light component can be reflected without attenuation. Reflection surface 9 in light components
Is passed through the reflecting surface 9 as shown by the broken line, refracted and reaches the light incident surface 8 of the adjacent reflecting shape portion 5, and is totally reflected by the reflecting surface 9 as shown by the broken line in FIG. The light component L2 is emitted from the light emitting surface 12.

Further, the light component L3 above the light component L1
Is refracted from the light exit surface 10 of the first reflection shape portion 5 and emitted as shown in the drawing, and is introduced into the next reflection shape portion 5 via the light entrance surface 8 and then reflected by the reflection surface 9. , Light emitting surface 1
The light is emitted in the normal direction of 2. These light components L1, L2
And L3, the light from the light source can be directed to the light emitting surface 12 with high efficiency. Here, a calculation result based on the embodiment will be described with reference to Table 1. First, assuming that the refractive index of the light guide plate n1 = 1.5 and the refractive index of air n2 = 1, the critical angle β = 41 °, and the refractive index of the light guide plate n1 = 1.33,
Assuming that the refractive index of air n2 = 1, the critical angle β = 48.5 °
It is known that

Although the used light guide plate has a refractive index n1 of 1.5, taking into account the use of various light-transmitting materials, the inclination angle θ of the reflection surface is set to a value close to the critical angle β = 41 °. A certain 45 ° was set. Therefore, in the embodiment, the inclination angle θ of the reflection surface is 45 °, the width of the reflection shape portion is A, the width of the groove is B, and the height of the reflection shape portion is C: A: B: C = 1:
The relationship was 1: 1.2. Table 1 shows that the incident angles θa = 0 °, 5 °, 10 °, 15 °, and 2 ° in FIG.
It is the result of performing each angle calculation for the value of 2.5 °.

[0036]

[Table 1] According to Table 1, the refraction angles θf that are reflected by one reflection surface having an inclination angle of 45 ° and are emitted toward the light emitting surface are refraction angles θa = 0 °, 5 °, 10 °, 15 °, and 22 °, respectively. 0.5 °, refraction angle θf = 0 °, 5 °, 10 °, 15 °, 2
2.5 °.

Here, when the refractive angle θf = 0 °, the light emitted from the light emitting surface coincides with the normal direction, so that the incident angle on the reflecting surface (θh = 45 °)> critical angle (β = 41) °), the light is totally reflected and becomes a light emitting surface having the maximum luminance.

Next, the meaning of the predetermined interval using at least two reflection shapes will be described.

In FIG. 3, the horizontal angle θg is an angle formed by a plane parallel to the light emitting surface when light incident at an angle smaller than the critical angle exits from the reflecting surface, and the critical angle β = 41 °.
Since it becomes the maximum at a slightly smaller angle, θi =
n1 / n2 × 41 ° = 61.5 °, θg = (61.5 °
−45 °) = 16.5 ° to the maximum horizontal angle θg = 16.
Get 5 °.

Therefore, light can reach the adjacent reflection shape part from the first reflection shape part and the predetermined interval B at which at least two reflection shape parts can be used is B ≦ A
Since / tan θg = A / tan 16.5 ° = 3.732A, B ≦ 3.732A may be set.

According to the predetermined interval B ≦ 3.732A,
Part of the light that has entered the reflective shape portion at an angle smaller than the critical angle, passes through the adjacent reflective shape portion, is reflected by the adjacent reflective surface, and is again emitted to the light emitting surface side, at least. Since two reflecting shapes can be used, light can be more effectively used, and brighter light can be obtained from the light emitting surface.

Further, according to Table 1, a part of the light incident on the first reflecting shape portion at θa1 = 15 ° is reflected by the reflecting surface and exits from the light emitting surface at a refraction angle θf1 = 15 °, but the rest is emitted. Some of the light is refracted by the reflective surface of the first reflective shape part,
An incident angle θa2 = θg = 7.5 ° is incident on the adjacent reflection shape part, and the refraction angle θf2 =
Light is emitted at 7.5 °, and each time this is repeated, the critical angle can be successively approached.

As described above, since the incident light can be reflected by using at least two reflecting shapes at the predetermined interval B,
The incident light that approaches the critical angle one after another can be emitted in the normal direction on the reflection surface of the reflection shape portion, and a bright light emission surface close to the maximum luminance can be obtained. In addition, the height C of the reflection shape portion
Can be set to any value according to various use conditions if C> A.

According to the light guide plate 1 described above, the light from the light source can be uniformly distributed on all the portions of the light emitting surface 12 using only the light guide plate, and the brightness of the light emitting surface separated from the light source can be reduced. The light can be emitted in the normal direction of the light emitting surface 12 or at a close angle without using the light. As a result, the above-mentioned prism film becomes unnecessary, and further, a reflection sheet provided to face the opposing surface of the light guide plate 1 becomes unnecessary. Light guide plate 1
It is not necessary to form a reflective surface in the case body that holds the light source at a predetermined position together with the light source.

In other words, according to the light guide plate 101 having the configuration described with reference to FIG. 11, some light components leak from the back surface side of the light guide plate 1,
Is provided, but this reflective sheet becomes unnecessary. Therefore, the light guide plates 1,... 1 can be configured to overlap in the vertical direction.

FIG. 2B is a sectional view taken along line XX of FIGS. 1A and 1B showing the third embodiment.

In this figure, the same reference numerals are given to the components already described and the description thereof is omitted. As shown, the thickness T 1 of the light guide plate 1 decreases as the distance from the light introduction surface 6 decreases. The thickness of the side wall at the end is T2 as the inclined surface.

By forming in this way, it is possible to allow the light component guided from the light introduction surface 6, particularly the parallel light component L, to reach the distant reflection-shaped portion 5, and the light-emitting surface The luminance from No. 12 is made uniform.

FIG. 4 is a luminance measurement result in which the light guide plate 1 of FIG. 2B is set in the light quantity measuring device described in FIG. 12 and plotted at every 5 degree angle.

According to the measurement results shown in FIG.
It was confirmed that the amount of light in the normal direction at an angle of zero degrees orthogonal to 2 had a peak value. Also, the angle 65 to 75
It was measured that light was slightly emitted in the degree direction and a part of the light was emitted to the facing surface side. Thus, the peak value is directed in the normal direction. Accordingly, when the liquid crystal display unit 22 is used as a backlight for illuminating the liquid crystal display unit 22, the amount of light from the front is sufficient and an optimal backlight is obtained.

FIG. 5 is a diagram showing a fourth embodiment of the present invention.
It is sectional drawing in the XX line of (a), (b). In this figure, the same reference numerals are given to the components already described, and the description is omitted. The fluorescent light 2 or the light emitting diode 7 which is a point or line light source is provided on each of the light introduction surfaces 6 and 6 of the light guide plate 1. Are arranged. The reflection shape part 5 is formed so that the reflection surfaces 9 and 9 have a mountain-shaped cross section having two inclination angles as shown in the figure, so that light from the left and right light sources is emitted toward the light emission surface 12. ing. According to the light guide plate 1 formed in this manner, the light amount can be increased.

Next, FIG. 6A is a cross-sectional view taken along line XX of FIGS. 1A and 1B showing the fifth embodiment.
FIG. 6B is a diagram showing the sixth embodiment shown in FIG.
It is sectional drawing in the XX line of (a), (b).

6 (a) and 6 (b), the components already described are denoted by the same reference numerals, and the description thereof will be omitted. When the description is omitted, the reflection shape portion 5 of the light guide plate 1 shown in FIG. 1 is formed. When the pitch P is 0.1 mm or more, for example, the light scattering sheet 21 can be seen from the light emitting surface 12 side, and a stripe pattern appears. Therefore, the light scattering sheet 21 is provided. However, the light scattering sheet 21 must be an extra part.

Therefore, the light scattering layer 33 is formed by subjecting the reflecting surface to sandblasting or roughening in an injection mold. According to the light guide plate obtained in this manner, for example, the light guide plate can be provided directly on the liquid crystal display unit 22, and the backlight can be formed at a minimum cost. Of course, a light component directed from the light source to the light scattering layer 33 at a critical angle or more cannot be directed to the reflection shape part 5, so that there is a slight decrease in luminance.

The light guide plate described above has a linear or rippled shape provided with the groove 4, and therefore has a limitation on the light incident direction. That is, the reflection surface of the reflection shape portion 5 must be inclined at a predetermined angle with respect to the light introduction surface 6.
Therefore, the restriction on the incident direction of light can be eliminated by forming the reflective shape portion 5 in a columnar or cylindrical shape.

FIG. 7A is a plan view of a surface light emitting device using a light guide plate according to a seventh embodiment using a line light source, and FIG. 7B is a view using the light guide plate according to the eighth embodiment using a point light source. It is a top view of a surface light emitting device. In FIG. 7, the case body for holding each component in the illustrated position is omitted from illustration, and the same reference numerals are given to the components already described, and the description is omitted. The light guide plate 1 is integrally formed in a staggered or random manner.

FIG. 8A is an external perspective view of the reflection shape part 5, and FIG. 8B is a cross-sectional view of the light guide plate using the cylindrical reflection shape part in FIG. FIG. In this figure, the reflection shape part 5 has a light entrance surface 8 and a light exit surface 10 formed on a cylindrical outer peripheral surface, and a reflection surface 9 formed in a conical or spherical shape with a radius R at the head.

With the above structure, the light from the light emitting diode 7 as the point light source or the light from the fluorescent lamp 2 as the line light source shown in FIG. Light can be uniformly distributed in all portions of the light emitting surface 12, and light can be emitted in the normal direction of the light emitting surface 12 or at a close angle without lowering the luminance of the light emitting surface remote from the light source.

FIG. 9A is a cross-sectional view taken along line XX of a light guide plate using the cylindrical reflection shape portion in FIG. 7, and FIG. 9B is a dot-like reflection shape portion. 5 is an external perspective view of FIG.

In FIG. 9, the reflection shape part 5 forms the light entrance surface 8 and the light exit surface 10 on a cylindrical outer peripheral surface,
A bottomed hole 30 is further formed at the center, and the reflecting surface 9 is formed in a conical or spherical shape over the bottomed hole 30 and the outer peripheral surface. By forming in this manner, in addition to the above-described cylindrical shape, the effect of transmitting light in the bottomed hole 30 is added, so that a further increase in luminance can be realized.

FIG. 10A is a partially cutaway perspective view of a surface light emitting device using a light guide plate, and is composed of a fluorescent lamp 2 as a line light source and a single light guide plate 1. 2 shows a state in which the two units are joined to and disposed on the case body 50 and the light guide plate 1 shown by a two-dot chain line can be added.

FIG. 10 (b) shows a concentric arc (ripple shape) when two light emitting diodes 7, 7 as point light sources are provided adjacent to the light introducing surfaces 6, 6.

With the above configuration, a backlight having an arbitrary size can be easily configured.

The present invention is not limited to the embodiments described below. For example, in addition to the liquid crystal display, the present invention can be configured as a novel lighting device, and further, for a color liquid crystal mobile phone and various large signboards. It may be used as a backlight, and the light from the light source can be evenly distributed on all parts of the light emitting surface only by the light guide plate, so that the luminance of the light emitting surface separated from the light source can be prevented from being lowered, and the light emitting surface can also be used. All models that need to emit light mainly in the normal direction can be used. In addition, since the overlapping can be performed as described above, color illumination can be performed by using a light source using RGB light emitting diodes.

[0065]

As described above, according to the present invention,
The light from the light source can be evenly distributed on all parts of the light-emitting surface only by the light guide plate, so that the brightness of the light-emitting surface separated from the light source can be prevented from lowering, and mainly in the normal direction of the light-emitting surface. An inexpensive light guide plate capable of emitting light and a surface light emitting device using the same can be provided.

[Brief description of the drawings]

1A is a plan view of a surface light-emitting device using a light guide plate according to a first embodiment using a linear light source, and FIG. 1B is a plan view showing surface light emission using a light guide plate according to a second embodiment using a point light source. It is a top view of an apparatus.

FIG. 2 (a) is a cross-sectional view taken along line XX in FIGS. 1 (a) and 1 (b).
FIG. 1B is a cross-sectional view taken along a line, and FIG.
It is sectional drawing in the XX line of (a), (b).

FIG. 3 is a partially enlarged view of FIG. 2A, and shows a case where the above-mentioned two reflection-shaped portions 5 are formed.

FIG. 4 is a luminance measurement result in which the light guide plate 1 of FIG. 2B is set in the light quantity measuring device described with reference to FIG. 12 and plotted at each angle of 5 degrees.

FIG. 5 is a sectional view taken along line XX of FIGS. 1A and 1B showing a fourth embodiment.

FIG. 6A is a diagram showing a fifth embodiment, FIG.
It is sectional drawing in the XX line of (a), (b). FIG. 6B shows the sixth embodiment, and FIG.
FIG. 3B is a sectional view taken along line XX of FIG.

FIG. 7A is a plan view of a surface light emitting device using a light guide plate according to a seventh embodiment using a line light source, and FIG. 7B is a surface using a light guide plate according to an eighth embodiment using a point light source. It is a top view of a light emitting device.

8 (a) is an external perspective view of a cylindrical reflection shape portion 5, and FIG. 8 (b) is a cross-sectional view taken along line XX in FIG.

9A is a cross-sectional view taken along line XX in FIG. 7, and FIG. 9B is an external perspective view of the cylindrical reflection shape portion 5.

10A is a partially cutaway perspective view of a surface light emitting device using a fluorescent lamp 2 and a light guide plate, and FIG. 10B is a perspective view of a surface light emitting device using a light emitting diode 7 and a light guide plate. It is a top view.

FIG. 11 is a cross-sectional view of a surface light emitting device using a light guide plate 101 disclosed in Japanese Patent Application Laid-Open No. H11-126030.

FIG. 12 is a schematic configuration diagram of a light quantity measuring device.

FIG. 13 is a luminance measurement result in which the light guide plate 1 of FIG. 11 is set in the light quantity measuring device described in FIG. 12 and plotted at every 5 ° angle.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light guide plate, 2 Fluorescent lamp (line light source) 3 Reflector 4 Groove part 5 Reflection shape part 6 Light introduction surface 7 Light emitting diode (Point light source) 8 Light entrance surface 9 Reflection surface 10 Light exit surface 11 Normal line 12 Light emission surface 21 Scattering sheet 22 LCD part β critical angle θ tilt angle

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F21Y 103: 00 G02F 1/1335 530

Claims (9)

[Claims] 1. A light guide plate formed of a light transmissive material for guiding light from a light source from a side light introduction surface to an inside and emitting light from a light emission surface, wherein the light guide plate is substantially the same as the light introduction surface. From a parallel light entrance surface, at least one reflection surface having an inclination angle that reflects incident light incident at a critical angle or more determined from the light transmitting material, and a light exit surface that is substantially parallel to the light introduction surface. A light guide plate, wherein a reflection shape portion to be formed is formed at a predetermined interval on a surface facing the light emitting surface. 2. The light guide plate according to claim 1, wherein the predetermined interval is set so as to reflect the incident light using at least two of the reflection shape portions. 3. The light guide plate according to claim 1, wherein a distance between the facing surface and the light emitting surface is reduced as the distance from the light introducing surface increases. 4. The light source is a point light source, and the reflection shape portion has a groove formed between the light incident surface and the light exit surface on both inner wall surfaces, and has a ripple around the point light source. And the light source is the linear light source, and is formed in a straight line parallel to the linear light source while interposing a groove having both the light entrance surface and the light exit surface as both inner wall surfaces. The light guide plate according to claim 1, wherein: 5. The reflection shape part is characterized in that the light entrance surface and the light exit surface are formed on a cylindrical outer peripheral surface, and the reflection surface is formed in a conical or spherical shape on a head. The light guide plate according to claim 1. 6. The reflection shape portion forms the light entrance surface and the light exit surface on a cylindrical outer peripheral surface, and forms the light entrance surface and the light exit surface in a central hole having a bottom. The light guide plate according to any one of claims 1 to 3, wherein the reflection surface is formed in a conical or spherical shape between the bottomed hole and the outer peripheral surface. 7. The light guide plate according to claim 1, wherein a light scattering process is performed on the light emitting surface. 8. A light-entering surface formed of a light-transmissive material for guiding light from a light source through a light-introducing surface on the side to emit light from the light-emitting surface, and a light-incoming surface substantially parallel to the light-introducing surface. A reflection shape portion formed by at least one reflection surface having an inclination angle for reflecting incident light incident at a critical angle or more determined from the light transmitting material, and a light exit surface substantially parallel to the light introduction surface; A light guide plate formed at a predetermined interval on a surface facing the light emitting surface, a light scattering sheet disposed adjacent to and in front of the light guide plate on the light emitting surface side, and further forward of the light scattering sheet. And a display unit disposed on the surface light-emitting device. 9. A light-entering surface formed of a light-transmitting material for guiding light from a light source through a light-introducing surface on the side and emitting light from the light-emitting surface, and a light-incoming surface substantially parallel to the light-introducing surface. A reflection shape portion formed by at least one reflection surface having an inclination angle for reflecting incident light incident at a critical angle or more determined from the light transmitting material, and a light exit surface substantially parallel to the light introduction surface; And a light guide plate formed at a predetermined interval on a surface facing the light emitting surface, while performing a light scattering process on a light emitting surface of the light guide plate, and a display unit disposed further in front of the light guide plate. A surface light emitting device using a light guide plate, comprising: