JP2000331522A - Lighting system and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize low consumption power and small sizing by installing a light guide body having facing reflecting surface and light outgoing surface, reflecting incident light incident in the inside from the side between the reflecting surface and the light outgoing surface toward the light outgoing surface with the reflecting surface and going out from the light outgoing surface; and a point light source for emitting light to a side surface. SOLUTION: A light guide body 2 for emitting incident light incident in the inside from a side surface 2c from an outgoing surface 2b and a light emitting diode 5 acting as a point light source for emitting light to the side surface 2c are installed, a diffusion member 6 for transmitting and diffusing light and emitting it to the side surface 2c of the light guide 2 is installed in the midway of a light guide path, and reflectors 7a, 7b acting as a reflecting member for reflecting light so that indirect light from the light emitting diode 5 incident in the side surface 2c of the light guide 2 are installed in the surroundings of the light guide path. Since the light emitting diode 5 is used as the point light source, consumption power is made lower compared with a fluorescent tube, an inverter circuit needed for the fluorescent tube is made unnecessary in the light emitting diode, and a lighting system is made small and portable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lighting device and a liquid crystal display device, and more particularly to a lighting device used for a reflection type liquid crystal display device used for a personal computer, a portable information terminal, a small television, and the like. .

[0002]

2. Description of the Related Art In recent years, personal computers and portable information terminals have been reduced in size and portability, and reduction of power consumption of image display apparatuses has become an important issue. For this reason, there are many image display devices using a reflective liquid crystal display device. The reflection type liquid crystal display device obtains the brightness of the screen by reflecting external light such as sunlight and indoor light. However, sufficient brightness cannot be obtained on the screen in a place with little external light. Therefore, there is a demand for a reflective liquid crystal display device with an illuminating device that does not hinder the illumination due to external light when there is much external light and illuminates the reflective liquid crystal panel when there is little external light and does not hinder the observer. Yes,
Some lighting devices using a light guide and a fluorescent tube as a light source have been employed.

Here, a description will be given of a reflection type liquid crystal display device using a conventional lighting device comprising a fluorescent tube and a light guide. As shown in FIG.
, A light guide 2, and a reflection member (hereinafter, referred to as a reflector) 3, and are arranged to face the display screen 4 a of the reflection type liquid crystal display device 4.

[0004] The fluorescent tube 1 is, for example, a hot cathode tube, a cold cathode tube, or the like, and is arranged in parallel with the side surface 2c of the light guide 2 as shown in FIG. As shown in FIG. 5, the light guide 2 is a transparent plate having a reflection surface 2a and an emission surface 2b formed opposite to each other, and a side surface 2 between the reflection surface 2a and the emission surface 2b.
c is incident on the reflection surface 2a.
The light is reflected toward b and exits from the exit surface 2b. On the reflection surface 2a, a plurality of grooves 2d are formed which become deeper as the distance from the side surface 2c on which light is incident.

[0005] The reflector 3 is configured to cover the periphery of the light guide path from the fluorescent tube 1 to the side surface 2 c of the light guide 2, and to allow light emitted from the fluorescent tube 1 to enter the side surface 2 c of the light guide 2. I have. The inner surface 3a of the reflector 3 is configured to have a high reflectance. This reflector 3
Is formed by evaporating a material having a high reflectance such as silver or aluminum on a resin sheet, and evaporating this sheet on a thin metal plate or a resin sheet.

[0006] The optical operation of the illumination device and the reflection type liquid crystal display device configured as described above will be described below.
As shown in FIG. 4, the light emitted from the fluorescent tube 1 is incident on the side surface 2c of the light guide 2. The light incident from the side surface 2 c of the light guide 2 propagates while totally reflecting inside the light guide 2. The propagating light is reflected by the groove 2d formed on the reflection surface 2a of the light guide 2, the total reflection condition is broken, and the light
From the emission surface 2b. The outgoing light emitted from the outgoing surface 2b of the light guide 2 is incident on the display screen 4a of the reflection type liquid crystal display device 4, passes through the liquid crystal layer inside the display screen 4a, reaches the reflector, and this reflector Is reflected back toward the lighting device. As described above, the reflection type liquid crystal display device 4 obtains the brightness of the screen with the light from the illumination device when the amount of incident light from outside is small.

[0007]

However, in the structure of the conventional illuminating device, since a fluorescent tube is used as a light source, a circuit for lighting the fluorescent tube is required. Tubes have the problem of high power consumption. In addition, since this illumination device is used in a liquid crystal display device, the liquid crystal display device has the same problem as described above.

An object of the present invention is to provide a lighting device and a liquid crystal display device which can be reduced in power consumption and size.

[0009]

According to the illuminating device of the present invention, a reflection surface and an emission surface are formed to face each other, and the incident light incident inside from the side surface between the reflection surface and the emission surface is reflected. A light guide that reflects the light toward the emission surface from the surface and emits the light from the emission surface; and a point light source that emits light to the side surface of the light guide.

According to the present invention, it is possible to obtain a lighting device that can be reduced in power consumption and reduced in size.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the first aspect of the present invention, a reflection surface and an emission surface are formed to be opposed to each other, and the incident light incident on the inside from the side surface between the reflection surface and the emission surface. And a light guide that reflects the light toward the light exit surface with the reflection surface and emits light from the light exit surface, and a point light source that emits light to the side surface of the light guide, the lighting device being provided. A compact lighting device with low power consumption can be obtained.

According to a second aspect of the present invention, a plurality of point light sources are provided along the longitudinal direction of the side surface of the light guide.
According to the illumination device described above, it is possible to make the light incident on the side surface of the light guide uniform, and to obtain a uniform surface light source from the emission surface of the light guide. Claim 3 of the present invention
The invention according to claim 1, further comprising a diffusing member that transmits and diffuses the light from the point light source and emits the light to the side surface of the light guide, in a light guide path from the point light source to the side surface of the light guide. Item 9. The lighting device according to Item 1, wherein the light from the point light source can be transmitted through the diffusion member, diffused and emitted to the side surface of the light guide, and the directivity of the point light source can be reduced. This makes it possible to make the light incident on the side surface of the light guide uniform, and to obtain a uniform surface light source from the exit surface of the light guide.

According to a fourth aspect of the present invention, a reflecting member for reflecting light is provided around a light guide path from a point light source to a side surface of the light guide, and the indirect light from the point light source is guided to the light guide path. The lighting device according to any one of claims 1 to 3, wherein the lighting device is provided so as to be incident on a side surface of the light body, wherein light from a point light source is indirectly incident on the side surface of the light guide. The distance from the point light source to the side surface of the light guide can be increased, and the directivity of the point light source can be reduced. This makes it possible to make the light incident on the side surface of the light guide uniform, and to obtain a uniform surface light source from the exit surface of the light guide.

According to a fifth aspect of the present invention, there is provided the lighting device according to the fourth aspect, wherein one end of the reflecting member is fixed to the point light source side of the reflecting surface and the emitting surface of the light guide via a double-sided adhesive tape. The reflecting member can be easily attached in the assembling process. In the invention according to claim 6 of the present invention, one end of the reflection member is attached to the reflection surface and the emission surface on the side of the point light source of the light guide, and the attachment width of the reflection member to the emission surface of the light guide is reduced. 5. The lighting device according to claim 4, wherein the width of the reflection member is greater than the width of the light guide attached to the reflection surface of the light guide, and the planar light from the emission surface of the light guide is made uniform. be able to.

According to a seventh aspect of the present invention, one end of the reflecting member is attached to the reflecting surface on the point light source side of the light guide and the emitting surface, and the reflecting member is connected to the emitting surface of the light guide. 5. The lighting device according to claim 4, wherein a light absorbing member is provided on the mounting portion, and when the light guide is viewed from a position above the reflection surface of the light guide, light reflected by the reflection member is conspicuous. Shining can be prevented.

According to an eighth aspect of the present invention, there is provided a liquid crystal display device provided with the illuminating device according to any one of the first to seventh aspects. A liquid crystal display device that can receive uniform planar illumination light from the light exit surface of the light guide can be obtained. Hereinafter, a lighting device and a liquid crystal display device of the present invention will be described based on specific embodiments.

(Embodiment 1) As shown in FIG. 1, a lighting device according to Embodiment 1 of the present invention has a reflecting surface 2a and an emitting surface 2a.
b are formed to face each other, and the incident light incident inside from the side surface 2c between the reflection surface 2a and the emission surface 2b is reflected by the reflection surface 2a.
A light guide 2 that reflects toward the emission surface 2b and emits from the emission surface 2b, and a light emitting diode 5 as a point light source that emits light on the side surface 2c of the light guide 2 is provided.
In the middle of the light guide path from the light guide 2 to the side surface 2c of the light guide 2, a diffusion member 6 that transmits and diffuses the light from the light emitting diode 5 and emits the light to the side surface 2c of the light guide 2 is provided. Reflectors 7a and 7b are provided around the periphery as reflecting members for reflecting light so that indirect light from the light emitting diode 5 is incident on the side surface 2c of the light guide 2.

The light emitting diode 5, as shown in FIG.
A plurality of light guides 2 are provided on the substrate 8 along the longitudinal direction of the side surface 2c. However, FIG. 2 does not show the reflector 7a. The substrate 8 is for disposing the light emitting diode 5, and is not particularly provided with an optical characteristic so as to effectively reflect light in the upper direction of the substrate.

As the diffusion member 6, for example, a light diffusion film (manufactured by Tsujiden Co., Ltd .: model name D123) is used. As shown in FIG. 1, the reflection member is formed in a substantially L-shape by combining a reflector 7 a fixed to the reflection surface 2 a of the light guide 2 and a reflector 7 b fixed to the emission surface 2 b of the light guide 2. ing. The space covered by the side surface 2c of the light guide 2, the reflectors 7a and 7b, and the substrate 8 is a cavity.

The light guide 2 is the same as that of the conventional example, and a plurality of grooves 2d are formed on the reflection surface 2a so as to become deeper away from the side surface 2c where the light is incident. Here, an optical operation of the illumination device will be described below. As shown in FIG. 1, the direct light from the light emitting diode 5 and the indirect light reflected by the reflectors 7a and 7b are incident on the diffusion member 6 in the light guide path. The diffusion member 6
The incident light is diffused and emitted toward the side surface 2c of the light guide 2. The light incident on the side surface 2c of the light guide 2 propagates while totally reflecting inside the light guide 2. The propagating light is
The light is reflected by the groove 2 d formed on the reflection surface 2 a of the light guide 2, and the light is emitted from the emission surface 2 b of the light guide 2 when the total reflection condition is broken.

For example, if the display screen 4a of the reflection type liquid crystal display device 4 shown in FIG. 4 is arranged to face the light exit surface 2b of the light guide 2, the light exits from the light exit surface 2b of the light guide 2. The emitted light is applied to the display screen 4a of the reflective liquid crystal display device 4.
And passes through the liquid crystal layer inside the display screen 4a to reach the reflector, where the light is reflected again toward the lighting device. As described above, the reflection type liquid crystal display device 4 obtains the brightness of the screen with the light from the illumination device when the amount of incident light from outside is small.

With this configuration, the light emitting diode 5 is used as a point light source, so that power consumption can be reduced compared to the conventional fluorescent tube 1. In addition, the fluorescent tube 1 of the conventional example requires an inverter circuit to emit light, but the light emitting diode 5 does not require the inverter circuit, so that the size and the portability can be reduced.

Further, since the diffusion member 6 is disposed in the light guide path from the light emitting diode 5 to the side surface 2c of the light guide 2, light from the light emitting diode 5 is transmitted and diffused by the diffusion member 6. Light can be emitted to the side surface 2c of the light guide 2,
The directivity of the light emitting diode 5 can be reduced. Thereby, the light when entering the side surface 2c of the light guide 2 can be made uniform, and a uniform surface light source can be obtained from the emission surface 2b of the light guide 2.

Also, as shown in FIG.
Since a and 7b are formed in a substantially L-shape, the light from the light emitting diode 5 as a point light source is reflected by the reflectors 7a and 7b until the light enters the side surface 2c of the light guide 2. The path can be lengthened, the directivity of the point light source can be weakened, and the light guide path can be lengthened without increasing the direction a perpendicular to the side surface 2c of the light guide 2, and the lighting device Can be prevented from increasing in the frame direction,
The size of the lighting device itself can be reduced.

When this lighting device is used for a liquid crystal display device, the lighting device can be reduced in size with low power consumption as described above, so that the liquid crystal display device can also be reduced in size with low power consumption. The substrate 8 is not for reflecting light effectively, but if necessary, the substrate 8
A light reflecting layer for reflecting light may be formed on the surface on which the light emitting diodes 5 are provided.

In the first embodiment, the light emitting diode 5
Are provided along the longitudinal direction of the side surface 2c of the light guide 2, but if the amount of incident light incident on the light guide 2 is sufficient, even if the light emitting diode 5 is singular, It has a similar effect. In the first embodiment, the diffusion member 6 that transmits, diffuses, and emits light is provided in the middle of the light guide path from the light emitting diode 5 to the side surface 2c of the light guide 2. If is not a problem, it may not be provided.

In the first embodiment, the light emitting diode 5
A substantially L-shaped reflector 7a, 7b is provided around the light guide path from the light guide 2 to the side surface 2c of the light guide 2, but when the reflectors 7a, 7b are further bent into a substantially U-shaped or the like. However, it can be prevented from increasing in the frame direction. (Embodiment 2) A lighting device according to Embodiment 2 of the present invention
As shown in FIG. 3, the reflector 7 according to the first embodiment described above is used.
The ends 7c and 7d of the light guides 2a and 2b are fixed to the reflection surface 2a and the light emission surface 2b of the light guide 2 on the side of the light emitting diode 5 via a double-sided adhesive tape 9, and the light guide 2 emits light from the reflector 7b. The mounting width b of the reflector 7a on the surface 2b is longer than the mounting width c of the light guide 2 on the reflection surface 2a of the reflector 7a, so that the light is absorbed by the mounting portion of the reflector 7b on the emission surface 2b of the light guide 2. That is, a member is provided.

The light-absorbing member may be any member having a color that absorbs light, such as black. For example, a double-sided adhesive interposed between the reflector 7b and the exit surface 2b of the light guide 2 is used. A black double-sided adhesive tape is used for the tape 9. With such a configuration, if the reflectors 7a,
When the mounting widths b and c of the light guide 7b to the light guide 2 are made equal, the reflected light from the reflector 7a passes through the path 10c after the path 10a, so that the light reflected from the exit surface 2b of the light guide 2 has a planar shape. Although the light is not uniform and becomes bright near the reflector 7b, in the second embodiment, the mounting width b of the reflector 7b on the light exit surface 2b of the light guide 2 is determined by the reflection of the light guide 2 of the reflector 7a. The light reflected by the reflector 7a is reflected by the reflector 7b after the path 10a and passes through the path 10b because it is longer than the mounting width c to the surface 2a. Light can be made uniform.

Further, since a black double-sided adhesive tape is used for a portion where the reflector 7b is attached to the light emitting surface 2b of the light guide 2, when this illumination device is used in combination with a reflection type liquid crystal display device or the like, When the light guide 2 is viewed from a position above the reflection surface 2a of the light guide 2, it is possible to prevent the reflected light from the reflector 7b from shining noticeably. Further, as shown in FIG. 3, the diffusion member 6 is connected to a portion 7 of the reflector 7b.
By fixing to the reflector 7a in a state where it is pressed against e, the lighting device can be easily assembled in the manufacturing process.

In the second embodiment, a black double-sided adhesive tape is used for the double-sided adhesive tape 9 interposed between the reflector 7b and the light exit surface 2b of the light guide 2, but light other than black is absorbed. Alternatively, a member that directly absorbs light may be provided on the light guide 2 or the reflector 7b without using the colored double-sided adhesive tape 9.

[0031]

As described above, according to the illuminating device of the present invention, the reflection surface and the emission surface are formed to face each other, and the incident light that has entered inside from the side surface between the reflection surface and the emission surface is controlled. By providing a light guide that reflects the light toward the emission surface from the reflection surface and emits the light from the emission surface, and a point light source that emits light to the side surface of the light guide, a fluorescent light as a conventional light source is provided. Power consumption can be reduced compared to a tube, and a circuit for illuminating a fluorescent tube as in the related art can be dispensed with, so that a downsized lighting device can be obtained with low power consumption. .

In the case where a plurality of the point light sources are provided along the longitudinal direction of the side surface of the light guide, light incident on the side surface of the light guide can be made uniform, and A uniform surface light source can be obtained from the exit surface. In the case where a diffusing member that transmits and diffuses light from the point light source and emits the light to the side surface of the light guide is provided in the middle of the light guide path from the point light source to the side surface of the light guide, the point light source Can be transmitted and diffused by the diffusion member and emitted to the side surface of the light guide, and the directivity of the point light source can be weakened. This makes it possible to make the light incident on the side surface of the light guide uniform, and to obtain a uniform surface light source from the exit surface of the light guide.

Further, a reflecting member for reflecting light is provided around a light guide path from the point light source to the side surface of the light guide so that indirect light from the point light source is incident on the side surface of the light guide. In this case, the light from the point light source can be indirectly incident on the side surface of the light guide, the distance from the point light source to the side surface of the light guide can be increased, and the directivity of the point light source is weakened. be able to. This makes it possible to make the light incident on the side surface of the light guide uniform, and to obtain a uniform surface light source from the exit surface of the light guide.

In the case where one end of the reflecting member is fixed to the reflecting surface and the emitting surface of the light guide on the side of the point light source via a double-sided adhesive tape, the reflecting member can be easily attached in the assembling process. Further, one end of the reflection member is attached to the reflection surface and the emission surface on the side of the point light source of the light guide, and the mounting width of the reflection member to the emission surface of the light guide is set to the width of the light guide of the reflection member. In the case where the width is longer than the width of attachment to the reflection surface, planar light from the emission surface of the light guide can be made uniform.

Further, one end of the reflection member is attached to the reflection surface on the point light source side of the light guide and the emission surface, and a member for absorbing light is provided at a portion where the reflection member is attached to the emission surface of the light guide. In this case, when the light guide is viewed from a position above the reflection surface of the light guide, it is possible to prevent the reflected light from the reflection member from shining noticeably. In addition, in the case of a liquid crystal display device provided with the above-described lighting device, a liquid crystal display device which can be reduced in size with low power consumption and can enjoy uniform planar illumination light from the emission surface of the light guide can be obtained. .

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of a lighting device according to a first embodiment of the present invention.

FIG. 2 is a detailed perspective view showing a configuration in the vicinity of a point light source of the illumination device according to the first embodiment.

FIG. 3 is an enlarged sectional view showing a connection portion between a reflector and a light guide according to a second embodiment of the present invention.

FIG. 4 is a cross-sectional view illustrating a configuration of a conventional illumination device and a reflective liquid crystal display device.

FIG. 5 is a perspective view showing a configuration of a conventional lighting device.

[Explanation of symbols]

 Reference Signs List 2 light guide 5 light emitting diode 6 diffusion member 7a reflector 7b reflector 8 substrate 9 double-sided adhesive tape

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Koki Nakabayashi 1006 Kazuma Kadoma, Osaka Pref. Matsushita Electric Industrial Co., Ltd.

Claims (8)

[Claims] 1. A reflecting surface and an emitting surface are formed opposite to each other, and incident light incident inside from a side surface between the reflecting surface and the emitting surface is reflected by the reflecting surface toward the emitting surface. A lighting device, comprising: a light guide that emits light from the emission surface; and a point light source that emits light on the side surface of the light guide. 2. The lighting device according to claim 1, wherein a plurality of point light sources are provided along a longitudinal direction of a side surface of the light guide. 3. A diffusing member for transmitting and diffusing light from the point light source and radiating the light from the side surface of the light guide is provided in the light guide path from the point light source to the side surface of the light guide. The lighting device according to claim 1. 4. A reflection member for reflecting light is provided around a light guide path from a point light source to a side surface of the light guide so that indirect light from the point light source is incident on the side surface of the light guide. The lighting device according to claim 1. 5. The lighting device according to claim 4, wherein one end of the reflecting member is fixed to the reflecting surface and the emitting surface of the light guide on the point light source side via a double-sided adhesive tape. 6. An end of the reflecting member is attached to the reflecting surface on the side of the point light source of the light guide and the exit surface, and the width of attachment of the reflecting member to the exit surface of the light guide is adjusted by the guide width of the reflecting member. The lighting device according to claim 4, wherein the lighting device is longer than a mounting width of the light body to the reflecting surface. 7. One end of a reflection member is attached to a reflection surface and a light emission surface of a light guide on a point light source side, and a light absorbing member is provided at a portion where the reflection member is attached to the light emission surface of the light guide. The lighting device according to claim 4. 8. A liquid crystal display device provided with the lighting device according to claim 1.