JP2002025324A - Lighting device and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lighting device with good lighting efficiency which can be easily manufactured. SOLUTION: The lighting device A has a spot-shaped light source 3 emitting light radially from front side to lateral side, and a light guide plate 2 which has a light incident surface 21 located in front of the light source 3, at one peripheral end part 2a of its lateral elongation, enabling to emit the light entered inside from the first light incident surface 21a outside, through a prescribed light emitting surface 23, while making the above light travel toward the other peripheral end part 2b of its lateral elongation. The light guide plate 2 comprises the second light incident surfaces 21b, 21c located at a side of the light source 3, and light reflection surfaces 22a, 22b which enable the light traveling inside the light guide plate 2 from the second light incident surface 21b, 21c to perform total reflection.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lighting device suitable for irradiating a desired planar area with light, and a liquid crystal display device provided with the lighting device.

[0002]

2. Description of the Related Art As a liquid crystal display device, there are a transflective type using a backlight system and a reflective type using a front light system. FIGS. 7 and 8 show specific examples of lighting devices used in these liquid crystal display devices.

[0003] The illuminating device D1 shown in Fig. 7 is provided with a light guide plate 8A made of a transparent synthetic resin, and a point light source 9A made up of LEDs. The back surface of one edge 80a of the light guide plate 8A is a light incident surface 81 facing the light source 9A.
It has been. The light source 9A is of a so-called top emission type in which the upper surface 90 is a main light emission surface. A plurality of recesses 84 are provided on the back surface 83 of the light guide plate 8A.
In the lighting device D1, when light emitted from the light source 9A is incident on the light guide plate 8A from the light incident surface 81, the light is thereafter repeatedly reflected on each side surface of the light guide plate 8A while repeating the other end portion. Proceed to 80b. At this time, the traveling direction of the light reaching each of the concave portions 84 changes abruptly, and a part of the light is smaller than the total reflection critical angle specified by the material of the light guide plate 8A with respect to the light emission surface 82. Incident at the angle of incidence. For this reason, light is emitted from each part of a certain area (light emitting surface 82) on the surface of the light guide plate 8A, and the light can be applied to a predetermined planar area of the liquid crystal display panel 7. Since the point light source 9A is used as the light source, the cost of parts can be reduced compared to the case where a so-called linear light source extending in a certain direction such as a cold cathode tube is used. Also, it is advantageous in reducing the size of the entire lighting device.

[0006] In an illumination device D2 shown in FIG. 8, an end surface of one end 80c of a light guide plate 8B is a light incident surface 81 opposed to a point light source 9B. The light source 9B is of a so-called side emission type in which one side surface 91 is a main emission surface. In the lighting device D2 as well, when light emitted from the light source 9B enters the light guide plate 8B from the light incident surface 81, the light travels toward the other end edge portion 80d of the light guide plate 8B while the light guide plate 8B Out of each part of the light emitting surface 82. Therefore, light can be applied to a predetermined planar area of the liquid crystal display panel 7.

[0005]

However, the conventional lighting devices D1 and D2 have the following disadvantages.

That is, light is emitted radially from the point light sources 9A and 9B, and much light is emitted not only in front of the main light emitting surfaces of the light sources 9A and 9B, but also toward the sides thereof. However, in the conventional lighting devices D1 and D2, light that travels to the side of the light sources 9A and 9B must be effectively taken into the light guide plates 8A and 8B and appropriately emitted from the light emission surface 82. Had become difficult.
More specifically, in the lighting device D1, light traveling in the directions indicated by reference numerals N1 and N2 from the light source 9A is transmitted through the light guide plate 8
It did not proceed inside A and was wasted. Similarly, in the lighting device D2, the light traveling from the light source 9B in the direction indicated by the symbol N3 was wasted. For this reason,
Conventionally, the use efficiency of the light emitted from the light sources 9A and 9B is reduced, and the amount of light emitted from the light emission surface 82 may be reduced. Further, as means for securing the amount of light emitted from the light emitting surface 82, there is a problem that the number of light sources must be increased or the light sources must be large.

The present invention has been conceived under such circumstances, and it is an object of the present invention to provide a lighting device which has high lighting efficiency and can be easily manufactured. Another object of the present invention is to provide a liquid crystal display device having such a lighting device.

[0008]

DISCLOSURE OF THE INVENTION In order to solve the above problems, the present invention employs the following technical means.

A lighting device provided by a first aspect of the present invention includes a point-like light source that emits light radially from the front to a side, and a first light incident surface located in front of the light source in a lateral width direction. At one end edge of the first
A light guide plate capable of emitting light incident inside from the light incident surface toward the other end in the lateral width direction and emitting the light to the outside from a predetermined light emitting surface. The light guide plate includes: a second light incident surface located on a side of the light source; and a light reflecting surface capable of totally reflecting light traveling from the second light incident surface into the light guide plate. It is characterized by having.

In the illuminating device having such a configuration, light propagating from the light source to the front thereof is guided into the light guide plate through the first light exit surface, so that the light is used as illumination light. In addition to the above, light that travels to the side from the light source can also travel into the light guide plate via the second light incident surface. And
This light is totally reflected by the light reflecting surface so that the light does not leak to the outside of one edge of the light guide plate as it is, and this light can be suitably used as illumination light. Become. As described above, according to the present invention, unlike the related art, not only light traveling from the light source in the front direction but also light traveling to the side can be effectively used as illumination light. Illumination efficiency can be made higher than before. Therefore, for example, it is possible to reduce the necessity of increasing the number of light sources or increasing the size of the light sources as a means for securing the amount of light emitted from the light exit surface of the light guide plate. Further, in the present invention, since the lighting efficiency can be increased without using a member separate from the light guide plate, an increase in the number of components as a whole is not caused, and the manufacturing thereof is facilitated. Can be.

[0011] In a preferred embodiment of the present invention, the one end edge of the light guide plate has a front surface and a back surface spaced apart in the thickness direction of the light guide plate, and the back surface has Since the concave portion in which the light source is accommodated is formed, the ceiling surface of the concave portion serves as the first light incident surface, and a pair of the concave portions facing each other in the width direction of the light guide plate. Each of the side wall surfaces is the second light incident surface, and the light reflecting surface is
While rising from the back surface toward the front surface so as to sandwich the recess in the width direction of the light guide plate,
It is formed as a pair of inclined surfaces that are inclined so that the distance between them increases toward the surface.

According to such a configuration, the light emitted from the light source toward the front thereof is incident on one end edge of the light guide plate from the ceiling surface of the concave portion of the light guide plate before being used as illumination light. be able to. On the other hand, for light traveling from the light source toward the lateral width direction of the light guide plate, after being made to enter into one end edge of the light guide plate from each of the pair of side wall surfaces of the concave portion, the light as the light reflection surface The light can be totally reflected by the pair of inclined surfaces, and this light can also be effectively used as illumination light. As described above, according to the configuration, it is possible to effectively use, as illumination light, light emitted from the light source toward at least three surfaces of the ceiling surface and the pair of side wall surfaces of the recess, respectively. It is more suitable for increasing the lighting efficiency.

[0013] In another preferred embodiment of the present invention, at least a part of the surface of the light guide plate totally reflects light passing through the ceiling surface of the concave portion from the light source in the direction of the other end edge. It is a possible curved or planar inclined surface.

According to such a configuration, the light that has passed through the ceiling surface of the concave portion and traveled into the light guide plate does not leak to the outside through the surface of the light guide plate as it is,
This light can be efficiently guided toward the other end of the light guide plate. Therefore, it is more suitable for increasing the lighting efficiency.

In another preferred embodiment of the present invention, at least one of the pair of side wall surfaces of the concave portion is formed as an inclined surface closer to the center of the concave portion in the width direction as the portion closer to the ceiling surface of the concave portion. I have.

According to such a configuration, when the light emitted from the light source passes through the side wall surface of the concave portion formed as the inclined surface, the light is refracted, thereby guiding the traveling direction of the light. It is possible to positively change the direction toward the surface of the light plate. As a result, it becomes possible to increase the incident angle when the light passing through the side wall surface subsequently enters the inclined surface as the light reflecting surface, and it is ensured that the light is totally reflected by the inclined surface. Or facilitated.

In another preferred embodiment of the present invention, a notch recess is formed at the one end edge of the light guide plate, so that the light guide plate is provided at the one end edge from the back surface of the light guide plate. A first side wall surface rising in the thickness direction of the first side wall surface, and a first side wall surface intersecting and connected to the first side wall surface so as to extend in a direction opposite to the direction from the first side wall surface to the other end edge portion. 2 is provided, and the light source is disposed in the notch recess, so that the first and second side wall surfaces correspond to the first and second light incident surfaces, respectively. The light reflecting surface is spaced apart from the second side wall surface in the thickness direction of the light guide plate, and the further away from the edge of the other end, the closer to the back surface of the light guide plate. It is formed as an inclined surface.

According to such a configuration, the light traveling from the light source toward the first side wall surface is allowed to proceed into the light guide plate as it is, and then the light guide plate is moved from one end edge to the other end. It can be advanced towards the edge.
On the other hand, the light that has traveled from the light source toward the second side wall surface passes through the second side wall surface and reaches the inclined surface serving as the light reflecting surface. The light can be totally reflected toward the edge of the other end. Therefore, the light that has passed through the second side wall surface can also be emitted from the light exit surface while guiding the inside of the light guide plate from one end edge to the other end edge of the light guide plate. The intended action is obtained.

[0019] In another preferred embodiment of the present invention, at least a part of the second side wall surface is inclined such that the portion farther from the edge of the other end is closer to the surface of the light guide plate. It has been.

According to such a configuration, when the light emitted from the light source passes through the second side wall surface, the light is refracted so that the traveling direction is changed to the other end of the light guide plate. It is possible to positively change the direction toward the part. As a result, it is possible to increase the incident angle when the light that has passed through the second side wall surface subsequently enters the light reflecting surface or another portion of the surface of the light guide plate. It is more preferable to suppress unnecessary leakage of light.

A liquid crystal display device provided by the second aspect of the present invention is a liquid crystal display device including a liquid crystal display panel and a lighting device for irradiating the liquid crystal display panel with light, wherein the lighting device The lighting device provided by the first aspect of the present invention is characterized in that it is used.

According to the illuminating device having such a configuration, the same effect as that described for the illuminating device provided by the first aspect of the present invention can be obtained, and the liquid crystal display image can be brightened with less power consumption. can do.

Other features and advantages of the present invention will become more apparent from the following description of embodiments of the present invention.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be specifically described below with reference to the drawings.

FIGS. 1 and 2 show an example of a lighting device according to the present invention and a liquid crystal display device provided with the lighting device. The liquid crystal display device B of the present embodiment is of a reflection type employing a front light method, and as is well shown in FIG. Is arranged. The lighting device A includes a light guide plate 2 and a point light source 3.

The light source 3 is, for example, an LED light source, and is configured as a surface mounting type light source device having a structure in which an LED chip (LED bare chip) 31 mounted on a substrate 30 is sealed with a transparent resin 32. It is. The light source 3 is surface-mounted on a substrate 40 of the liquid crystal display device B. The light source 3 emits light radially from the upper surface 32a of the transparent resin 32 and a plurality of side surfaces.
This is a top emission type in which the amount of light emitted from the light source is greater than the amount of light emitted from each side surface. When the liquid crystal display panel 1 is a color liquid crystal, the emission color of the light source 3 is, for example, white, but the specific color is not limited.

The light guide plate 2 is made of a transparent synthetic resin such as polycarbonate or acrylic resin, and has a rectangular plate shape as a whole. However,
One edge 2a of the light guide plate 2 in the lateral width direction (arrow x direction)
Is made thicker than the thickness of the other parts. The light guide plate 2 has a plurality of surfaces described later, and each of the plurality of surfaces is a smooth surface (mirror surface) which is convenient for totally reflecting the received light.

One edge 2a of the light guide plate 2 is
Back surface 20 spaced apart in the thickness direction from front surface 20a
b, a concave portion 21 formed on the back surface 20b, a pair of light reflecting surfaces 22a and 22b, and an end surface 20c.
The recess 21 is for accommodating and arranging the light source 3 therein, and as shown well in FIG. 2, a substantially central portion of one end edge 2 a of the light guide plate 2 in the vertical width direction (direction of arrow y). It is provided in. In the present embodiment, one recess 21 and one light source 3 are provided, but the present invention is not limited to this, and a configuration in which a plurality of these are provided may be used.

The concave portion 21 has a form in which the bottom portion is opened in a rectangular shape. The surface defining the concave portion 21 includes a ceiling surface 21a and a pair of sides facing each other in the width direction of the light guide plate 2. The wall surfaces 21b and 21c and a pair of side wall surfaces 21d and 21 facing each other in a direction intersecting with the wall surfaces 21b and 21c.
e (see FIG. 2). The ceiling surface 21a corresponds to an example of a first light incident surface according to the present invention, and faces the upper surface 32a of the light source 3. A pair of side wall surfaces 21b,
Each of 21c corresponds to an example of the second light incident surface in the present invention, and faces the side surface of the transparent resin 32 of the light source 3. The side wall surface 21b is formed on the back surface 2 of the light guide plate 2.
It is an inclined surface that becomes closer to the center in the width direction of the concave portion 21 as it rises from 0b. In the present embodiment, the concave portion 21 is formed as having a pair of side wall surfaces 21d and 21e, but the present invention is not limited to this, and the concave portion 21 extends over the entire length of the light guide plate 2, for example. It may be formed in a different form.

The pair of light reflecting surfaces 22a and 22b rise from the back surface 20b of the light guide plate 2 so as to sandwich the recess 21 in the width direction of the light guide plate 2, and the interval between them increases as the rising amount increases. It is formed as a flat inclined surface which is inclined at a right angle. The angle of inclination of these light reflecting surfaces 22a and 22b is
When the light reflecting surfaces 22a and 22b receive the light that has passed through the side wall surfaces 21b and 21c, the angle is set such that the light can be totally reflected. Of the surface 20 a of the light guide plate 2, the portion directly above the ceiling surface 21 a of the concave portion 21 and the vicinity thereof can totally reflect the light passing upward through the ceiling surface 21 a in the direction of the other end 2 b of the light guide plate 2. The inclined surface 20a 'is a curved surface.

The middle portion in the width direction and the other end portion 2b of the light guide plate 2 are regions where light can be emitted to the outside while the light travels inside thereof. In this region, the surface 20a of the light guide plate 2 is formed in an uneven shape. More specifically, in this portion, a plurality of convex portions 26 having a triangular cross section having two types of inclined surfaces 26a and 26b having different inclination directions and angles are formed side by side in the width direction of the light guide plate 2. ing. Each convex portion 26 extends uniformly in the vertical width direction of the light guide plate 2. The entire area or substantially the entire area of the back surface 20d of the light guide plate 2 is a planar light emission surface 23.

In the light guide plate 2, when light travels from the inside of one end edge 2a of the light guide plate 2 to the middle portion in the width direction, this light is transmitted to the other end edge 2b while repeating total reflection by the front surface 20a and the back surface 20d. It is going to progress toward. In this case, when the light reaches the inclined surface 26a of the surface 20a, the incident angle of the light on the inclined surface 26a is increased by the amount of the inclination of the inclined surface 26a in a predetermined direction. It is likely to be larger than a predetermined total reflection critical angle (for example, 45 °) determined by the refractive index of 2, and to be totally reflected. Therefore, the ratio of light emitted from the surface 20a of the light guide plate 2 to the outside is small. On the other hand, the inclined surface 26b of the surface 20a serves to reflect the received light so as to be incident on the light exit surface 23 of the light guide plate 2 at a small incident angle. Therefore, the light that has reached the light exit surface 23 after passing through the inclined surface 26b is
The incident angle becomes smaller than the critical angle for total reflection, and the possibility of transmission through the light exit surface 23 as it is becomes high.
Light is emitted downward from each of the three points.

The liquid crystal display panel 1 is mounted on the substrate 40 such that the upper surface thereof faces the light exit surface 23 of the light guide plate 2. The liquid crystal display panel 1 can have the same configuration as an existing reflective liquid crystal display panel. For example, a pair of transparent substrates 10a and 10b, a liquid crystal 11 sealed between them, and a pair of polarizing plates It has a configuration including 12a, 12b, and a reflection plate 13. A plurality of transparent electrodes 14a, 14b are provided on the pair of transparent substrates 10a, 10b.
Films 15a and 15 for imparting twist to liquid crystal 11 and liquid crystal 11
b is provided. In the liquid crystal display device B,
When light is emitted downward from the light emission surface 23 of the light guide plate 2,
This light travels downward in the liquid crystal display panel 1 and is reflected upward by the reflector 13. The reflected light then passes through the liquid crystal display panel 1 again, passes through the light guide plate 2, and proceeds to the front (upper) of the liquid crystal display device B. By such an operation, the liquid crystal image of the liquid crystal display panel 1 can be recognized from the front through the light guide plate 2.

Next, the operation of the illumination device A and the liquid crystal display device B having the same will be described.

First, when the light source 3 is driven, the light source 3
Is emitted from the ceiling surface 21 of the concave portion 21 of the light guide plate 2.
a and a plurality of side wall surfaces 21b to 21e, and advances into one end edge 2a of the light guide plate 2. Most of the light that has passed through the ceiling surface 21a is then converted to the inclined surface 2a of the surface 20a of the light guide plate 2.
0a ', and the light is totally reflected by the inclined surface 20a' toward the middle portion in the width direction of the light guide plate 2 and the other end 2b. Therefore, the light is irradiated toward the liquid crystal display panel 1 from various parts of the light emitting surface 23 while appropriately traveling in the light guide plate 2.

On the other hand, a pair of side wall surfaces 21b, 2
1c passes through a pair of light reflecting surfaces 22a and 22a.
2b is reached. Since the light reflecting surfaces 22a and 22b are formed as predetermined inclined surfaces, the light can be totally reflected by the light reflecting surfaces 22a and 22b,
The light can be prevented from leaking out of the light guide plate 2 as it is. Since the side wall surface 21b of the concave portion 21 is formed as a predetermined inclined surface, when light passes through the side wall surface 21b, the light can be positively refracted so that the traveling direction is upward. (Refer to the enlarged view of the main part in FIG. 1). Therefore, the light incident angle θ on the light reflecting surface 22a when the light passing through the side wall surface 21b reaches the light reflecting surface 22a is increased, and the light source 3
It is possible to reduce the possibility that the light traveling to 2a is transmitted to the outside as it is. If the incident angle θ can be increased, the inclination angle α of the side wall surface 21b can be increased without impairing the total reflection function of the light of the side wall surface 21b. If the inclination angle α is increased, the width L of the side wall surface 21b is increased.
Can be reduced, so that one end edge 2 of the light guide plate 2
This is advantageous in reducing the amount of “a” protruding to the side of the liquid crystal display panel 1.

The light totally reflected by the light reflecting surface 22a is then applied to the middle portion of the light guide plate 2 in the width direction and the other end portion 2
Proceed toward b. Most of the light that has passed through the side wall surface 21c of the concave portion 21 and has been totally reflected by the light reflecting surface 22b is subsequently totally reflected by the surface 20a and the end surface 20c of the light guide plate 2, so that the light in the width direction of the light guide plate 2 It will progress toward the middle part and the other end edge part 2b. In addition,
The light that has passed through the side wall surfaces 21d and 21e of the concave portion 21 travels mainly in the vertical width direction of the light guide plate 2, but since the light travels in various directions, a part of the light travels to each part of the light guide plate 2. , It can be expected that the light guide plate 2 proceeds toward the middle portion in the width direction and the other end portion 2b.

As described above, in the lighting device A,
Not only the light emitted from above the light source 3 (in front of the light source 3), but also the light emitted in the horizontal direction (both sides of the light source 3) from the one edge 2a to the other edge of the light guide plate 2. 2b
In the direction of. Therefore, in this illuminating device A, the amount of light emitted from the light exit surface 23 can be increased as compared with the case where only the light emitted upward from the light source 3 proceeds toward the other end 2b. , Can increase the lighting efficiency. For this reason, the light source 3
As, while using a small one with low power consumption,
The display image on the liquid crystal display panel 1 can be brightened.

FIGS. 3 to 6 show other examples of the illuminating device according to the present invention or a liquid crystal display panel provided with the illuminating device. In these drawings, the same or similar elements as those in the above embodiment are denoted by the same reference numerals as those in the above embodiment.

The liquid crystal display Ba shown in FIG. 3 is of a transflective type employing a backlight system.
The light guide plate 2A of a is disposed behind (below) the liquid crystal panel 1A. The lighting device Aa is provided with a surface 20a of the light guide plate 2A.
Is a planar light emission surface 23A that emits light upward, and this configuration is different from the illumination device A of the above embodiment in this point. For example, a plurality of recesses 29 are provided on the back surface 20d of the light guide plate 2A. In the illumination device Aa, the light hitting each of the concave portions 29 is reflected in a form close to the scattered reflection, and the possibility that the reflected light is incident on the light exit surface 23A at a small incident angle is increased. The emission of light from the surface 23 is promoted. The liquid crystal display panel 1A replaces the reflection plate 13 of the liquid crystal display panel 1 of the above embodiment,
The transflective plate 13a is provided. In the liquid crystal display device Ba, when light is emitted upward from the light exit surface 23 of the light guide plate 2A, the light passes through the semi-transmissive reflection plate 13a and the inside of the other liquid crystal display panel 1A and passes through the liquid crystal display panel 1A. It advances to the front (upper surface), whereby the liquid crystal screen can be recognized from the front of the liquid crystal display panel 1A. When the illumination device Aa is not used, the liquid crystal screen can be recognized by transmitting external light downward through the liquid crystal display panel 1A and reflected upward by the transflective plate 13a.

Although the liquid crystal display device Ba is different from the liquid crystal display device B of the above embodiment in the illumination method, the configuration of each part of the one end portion 2a of the light guide plate 2 and the light source 3 is the same. Most of the light emitted from 3 can be effectively used as illumination light for the liquid crystal display panel 1A using the light guide plate 2A. As described above, in the present invention, the liquid crystal display device can be configured as either a backlight type or a front light type, which is another type of illumination according to the present invention described later. The same applies to the case where an apparatus is used.
In the present invention, any one of the front and back surfaces of the light guide plate may be a light emitting surface.

In the structure shown in FIG. 4A, the light guide plate 2 is provided with a side wall surface 21c and a light reflection surface 22b located on one side of the light source 3, whereas the light guide plate 2 according to the first embodiment is different from the first embodiment. No portion corresponding to the side wall surface 21a and the light reflection surface 22a is provided. In the configuration shown in FIG. 4B, on the contrary, the light guide plate 2 has the side wall surface 21a.
And the light reflecting surface 22a are provided, but the side wall surface 21c and the light reflecting surface 22b are not provided.

In these configurations, in any case, of the light emitted from the light source 3, in addition to the light traveling in front (upward) of the light source 3, the light traveling to one side of the light source 3 is transmitted. The light guide plate 2 can be advanced toward the middle portion and the other end portion in the width direction of the light guide plate 2, and can be effectively used as illumination light. Therefore, the illumination efficiency can be increased as compared with the conventional one. However, in these configurations, light traveling in the directions indicated by arrows Na and Nb in the figure is wasted, and from the viewpoint of further improving the illumination efficiency, the light emitting device according to the first embodiment shown in FIGS. It is preferable to have a configuration.

The liquid crystal display device Bb shown in FIG.
B has a configuration in which first and second side wall surfaces 28a and 28b are formed on one end edge 2a by forming cutout recess 21A on one end edge 2a.
The first side wall surface 28a is a surface that rises upward from the back surface 20e of the light guide plate 2B. Second side wall surface 28b
Extends from the upper edge of the first side wall surface 28a toward the tip of the one end edge 2a. However, the second side wall surface 28
b is a flat inclined surface that is closer to the surface 20a of the light guide plate 2B as it approaches the tip of the one end edge 2a. The cutout recess 21A may extend over the entire length of the light guide plate 2B or may have an appropriate width in the vertical width direction.

The light source 3A is an LED mounted on the substrate 30.
The chip 31 has a structure sealed with a transparent resin 32, but is configured as a so-called side emission type, which is different from the light source 3 of the above-described embodiment. When the light source 3A is mounted on the horizontal substrate 40 using solder H, the amount of light emitted from one lateral side surface 32b of the transparent resin 32 is smaller than the amount of light emitted from the other side surface or top surface. Side emission type. The light source 3A is disposed in the cutout recess 21A such that the side surface 32b faces the first side wall surface 28a. Therefore, in this embodiment,
The first side wall surface 28a corresponds to the first light incident surface according to the present invention, and the second side wall surface 28b corresponds to the second light incident surface according to the present invention.

The portion of the surface 20a of the light guide plate 2B located directly above the second side wall surface 28b is a light reflection surface 22c. The light reflecting surface 22c is formed on the second side wall surface 28.
b of the light guide plate 2B at the other end 2b.
Is a flat or curved inclined surface that is closer to the back surface 20e of the light guide plate 2B as it approaches the tip of the one edge portion 2a so that the light can be totally reflected. An inclined surface 22d connected to the light reflecting surface 22c is also formed on the surface 20a of the light guide plate 2B.
The inclined surface 22d smoothly connects the one end edge 2a of the light guide plate 2B to the middle portion in the width direction, thereby forming the light guide plate 2B.
In this way, it is possible to prevent a sudden change in shape from being generated as much as possible, and to prevent light from leaking out of the sudden change in shape. The light guide plate 2B has a predetermined area on a surface 20a thereof serving as a light emission surface 23 for emitting light toward the liquid crystal display panel 1A.

In the liquid crystal display device Bb, the light source 3
The light emitted in the horizontal direction from the side surface 32b of A can be advanced into the light guide plate 2B via the first side wall surface 28a. Since the traveling direction of the light coincides with the width direction of the light guide plate 2B, the light is directly transmitted to the light guide plate 2B.
The inside advances toward the other end edge 2b. On the other hand, the light emitted upward from the light source 3A reaches the light reflection surface 22c after traveling into the light guide plate 2B via the second side wall surface 28b. Then, this light is reflected on the light reflecting surface 22.
c, the light is totally reflected toward the other end 2b of the light guide plate 2B. Therefore, in this liquid crystal display device Bb,
In addition to the light emitted from the light source 3A in the horizontal direction, light emitted upward can be effectively used as illumination light. Since the second side wall surface 28b is a predetermined inclined surface, when light passes through the second side wall surface 28b, the light travels in the direction of the other end 2b of the light guide plate 2B. Can be refracted so as to be swung. Therefore, it is possible to increase the incident angle of light on the light reflecting surface 22c or the inclined surface 22d by that much, and to eliminate or reduce the possibility that the light leaks from the light reflecting surface 22c or the inclined surface 22d to the outside as it is. can do.

The liquid crystal display device Bc shown in FIG.
The configuration of the liquid crystal display device Bb shown in FIG. 5 is different from that of the liquid crystal display device Bb shown in FIG. 5 in that the second side wall surface 28b of B is formed in an uneven shape. More specifically, the liquid crystal display device Bc
In this case, the second side wall surface 28b of the light guide plate 2B is formed in a saw-tooth shape, so that the one end edge portion 2 of the light guide plate 2B is formed.
A plurality of inclined surfaces 28b 'are formed closer to the surface 20a of the light guide plate 2B as approaching the front end of the light guide plate 2B.

According to such a configuration, when the light emitted upward from the light source 3A passes through each inclined surface 28b ', the light travels in the direction of the other end 2b of the light guide plate 2B.
It is refracted so as to swing closer. Therefore, also in this case, similarly to the embodiment shown in FIG.
2c and the angle of incidence of light on the inclined surface 22d are increased,
The effect is obtained that leakage of light from these portions can be suppressed. However, if a plurality of inclined surfaces 28b 'are provided on the second side wall surface 28b as in the liquid crystal display device Bc, the inclination angles and the like thereof can be individually made different, and the light reflecting surface 22c and inclined surface 22
This is more preferable for preventing the leakage of light from d.

The present invention is not limited to the contents of the above-described embodiment, and the specific configuration of each part can be freely changed in various ways.

The specific number, size, position, forming method and the like of the first and second light incident surfaces referred to in the present invention can be variously changed. As the light source, LE mounted on the board
The structure is not limited to the structure in which the D chip is resin-sealed, and may be, for example, an LED lamp type having lead terminals or a single LED chip (LED bare chip). As the light guide plate according to the present invention,
The first and second light incident surfaces may be provided not only at one edge of the light guide plate but also at a plurality of edges. Uses of the lighting device according to the present invention include:
The present invention is not necessarily limited to the illumination application of the liquid crystal display device, and can be used for various applications for irradiating a planar region with light. The liquid crystal display device according to the present invention may be either a color image display or a monochrome image display, and the type of liquid crystal and the driving method thereof are not limited.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an example of a lighting device according to the present invention and a liquid crystal display device including the same.

FIG. 2 is a plan view of FIG.

FIG. 3 is a cross-sectional view showing another example of the illumination device according to the present invention and a liquid crystal display device including the same.

FIGS. 4A and 4B are cross-sectional views of main parts showing another example of the lighting device according to the present invention.

FIG. 5 is a cross-sectional view showing another example of the illumination device according to the present invention and a liquid crystal display device including the same.

FIG. 6 is a cross-sectional view showing another example of the illumination device according to the present invention and a liquid crystal display device including the same.

FIG. 7 is an explanatory diagram showing an example of the related art.

FIG. 8 is an explanatory diagram showing another example of the related art.

[Explanation of symbols]

 A, Aa Lighting device B, Ba-Bc Liquid crystal display device 1, 1A Liquid crystal display panel 2, 2A Light guide plate 2a One end edge (of light guide plate) 2b Other end edge (of light guide plate) 3 Light source 20a Surface (light guide plate) 20b Back surface (of light guide plate) 21 Concave portion 21a Ceiling surface (first light incident surface) 21b, 21c Side wall surface (second light incident surface) 22a, 22b Light reflecting surface 23 Light emitting surface

Claims (7)

[Claims] 1. A point-like light source that emits light radially from the front to the side, and a first light incident surface located in front of the light source at one edge in a lateral width direction, and A light guide plate capable of emitting light incident inside from the first light incident surface toward the other end in the lateral width direction and emitting the light to the outside from a predetermined light emitting surface. A light guide plate, a second light incident surface located on a side of the light source, a light reflecting surface capable of totally reflecting light traveling from the second light incident surface into the light guide plate, A lighting device, comprising: 2. The light guide plate according to claim 1, wherein the one end edge has a front surface and a back surface that are spaced apart in a thickness direction of the light guide plate, and the back surface has a recess for accommodating the light source. By being formed, the ceiling surface of the concave portion serves as the first light incident surface, and each of the pair of side wall surfaces of the concave portion facing each other in the width direction of the light guide plate is the second light incident surface. And the light reflecting surface rises from the back surface toward the front surface so as to sandwich the recess in the width direction of the light guide plate, and the distance between the light reflection surfaces increases toward the front surface. The lighting device according to claim 1, wherein the lighting device is formed as a pair of inclined surfaces. 3. At least a part of the surface of the light guide plate,
The lighting device according to claim 2, wherein the lighting device has a curved or planar inclined surface capable of totally reflecting light that has passed through the ceiling surface of the concave portion from the light source toward the edge of the other end. 4. The concave portion according to claim 2, wherein at least one of the pair of side wall surfaces of the concave portion is an inclined surface that is closer to the center in the width direction of the concave portion as the portion closer to the ceiling surface of the concave portion. Lighting equipment. 5. The light guide plate has a notch recess formed at one end edge thereof, so that the one end edge portion has a first side rising from a back surface of the light guide plate in a thickness direction of the light guide plate. A wall surface, and a second side wall surface intersecting with the first side wall surface so as to extend in a direction opposite to the direction from the first side wall surface to the other end edge portion. In addition, since the light source is disposed in the cutout recess, the first and second side wall surfaces are respectively the first and second light incident surfaces, and the light reflecting surface is The light guide plate is formed at an interval with respect to the second side wall surface in the thickness direction of the light guide plate, and is formed as an inclined surface closer to the back surface of the light guide plate as the portion is further away from the other end edge; The lighting device according to claim 1. 6. At least a part of the second side wall surface,
The lighting device according to claim 5, wherein an inclined surface is inclined so as to be closer to a surface of the light guide plate as a portion farther from the edge of the other end. 7. A liquid crystal display device comprising: a liquid crystal display panel; and an illumination device for irradiating the liquid crystal display panel with light, wherein the illumination device according to claim 1 is used as the illumination device. A liquid crystal display device, wherein the device is used.