JP2000056138A - Light transmission plate and surface light emission body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light transmission plate capable of realizing a surface light emission body suitably illuminating an object arranged downward and particularly excellent as a light source of a reflection type LCD and to provide a surface light emission body. SOLUTION: The surface light emission body 1 is provided with a fluorescent tube 10, a reflector 12 and the light transmission plate 14. The fluorescent tube 10 is prolonged in the direction vertical to a paper surface, and the reflector 12 surrounds the fluorescent tube 10, and is prolonged in the same direction as the fluorescent tube 10. In the surface light emission body 1, the side shape of the light transmission plate 14, that is, the shape of the light transmission plate 14 at the time of viewing from the axial direction of the fluorescent tube 10 is constituted so that the thickness is reduced from a base end surface 14e toward a tip surface 14t. As the shape of the light transmission plate 14 various shapes of a planar shape, a wedge shape and an inverted ship bottom shape may be adopted. The surface or the front surface 14s of the light transmission plate 14 is made into a rough surface at need.

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 and a surface light emitter using the same, and more particularly, to a light guide plate capable of realizing a surface light emitter capable of suitably illuminating an object disposed below. And the surface light emitter.

[0002]

2. Description of the Related Art Since liquid crystals do not emit light,
A liquid crystal display (LCD) requires an external light source. Conventionally, a backlight installed on the back of a liquid crystal panel has been widely used as such a light source. Light has become essential. In addition, most of recent LCDs are transmissive LCDs that have a built-in backlight on the back and illuminate through a liquid crystal panel, except for wristwatches and calculators where power consumption is of the utmost importance. Backlights have been an important component of LCDs.

However, in response to the recent so-called mobileization of information devices and AV devices, attempts have been made to extend the operating time of mobile devices by removing the backlight, which is a component that consumes the most power in transmissive LCDs. In response to this demand, a reflective TFT that is bright, easy to see, and can display color without a backlight.
Liquid crystal displays are being developed.

[0004]

However, in the above-mentioned reflection type LCD, although a good image is displayed in the daytime or a relatively bright place, external light such as natural light or indoor illumination light is used as a light source. As a fate of the reflective LCD, image display tends to be insufficient at night or in a dark place, and in some cases, there is a problem that the image display itself cannot be visually recognized.

[0005] Further, not only the reflection type LCD but also a flat plate such as a book or other document is desired to be viewed at night or in a dark place, and the above-mentioned problem of insufficient or impossible viewing occurs.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and has as its object to illuminate an object disposed below, preferably a reflective LCD. It is an object of the present invention to provide a light guide plate capable of realizing a good surface light emitter as a light source of the above, and the surface light emitter.

[0007]

Means for Solving the Problems The inventors of the present invention have made intensive studies to achieve the above object, and as a result, are constituted by using a light guide plate having a specific shape and a specific processing, and if necessary. It has been found that the above object can be achieved by a surface light emitter that operates independently, and the present invention has been completed.

That is, the light guide plate of the present invention is a light guide plate used for a surface illuminator for illuminating an object to be illuminated disposed below, and has a side surface shape of a linear shape installed on the surface illuminator. When viewed from the axial direction of the light source, the light source has a wedge shape or an inverted ship bottom shape.

Further, another light guide plate of the present invention is a light guide plate used for a surface illuminator for illuminating an object to be illuminated disposed below, and a side surface shape of the light guide plate is set on the surface illuminator. When viewed from the axial direction of the linear light source, the linear light source has a flat plate shape, a wedge shape, or an inverted ship bottom shape, and a whole or a part of a top surface thereof is roughened.

Further, the surface illuminant of the present invention is a surface illuminator for illuminating an object to be illuminated disposed below, comprising a linear light source, a reflecting means surrounding the linear light source, and a linear light source. A light guide plate provided with one end face close to the light source, wherein the light guide plate is a light guide plate as described above.

In a preferred embodiment of the surface illuminator of the present invention, the object to be illuminated is a reflective liquid crystal panel, and the surface illuminator operates independently of the reflective liquid crystal panel.

[0012]

In the present invention, the object to be illuminated is placed below the light guide plate.
That is, it is arranged on the back side of the light guide plate with respect to the observer. In other words, the light guide plate is arranged between the illuminated object and the observer,
The object to be illuminated is illuminated via the light guide plate. When the object to be illuminated is a liquid crystal panel, the light source of a conventional transmission type LCD is a backlight, whereas the surface light emitter of the present invention is a so-called front panel. Functions as a light.

In the present invention, a linear light source is disposed at one end of the light guide plate, and the side shape of the light guide plate is formed in a specific shape. Therefore, the illuminated object disposed below the light guide plate is displayed brightly. Further, if the top surface of the light guide plate, that is, the surface on the observer side is roughened, the illuminated object can be displayed more brightly.

When the object to be illuminated is a reflection type liquid crystal panel, a reflection type LCD device having an integrated light source can be manufactured by mounting the surface light emitter of the present invention on the front surface of the panel. In this case, if the surface light emitter can be operated independently of the liquid crystal panel, the surface light emitter can be operated only when natural light or indoor lighting is insufficient, such as at night or in a dark place, The power consumption of the entire device can be reduced.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a light guide plate and a surface light emitter according to the present invention will be described in detail. As described above, the surface light emitter of the present invention includes the linear light source, the reflection means surrounding the linear light source, and the light guide plate having one end face close to the linear light source. A specific example is shown in FIG.

FIG. 1 is a schematic side view showing an example of a surface light emitter of the present invention. In FIG. 1, the surface light emitter 1 is a fluorescent tube 10 which is an example of a linear light source and an example of a reflection means. A certain reflector 12 and a light guide plate 14 are provided. The fluorescent tube 10 extends in a direction perpendicular to the plane of the drawing, and the reflector 12 surrounds the fluorescent tube 10 and extends in the same direction as the fluorescent tube.

The light guide plate 14 is installed with the base end surface 14e close to the fluorescent tube 10. When the light guide plate 14 is positioned below the light guide plate 14, that is, with respect to the observer 30, the light guide plate 14 is On the back surface or the bottom surface 14r side, a reflection type LCD 20, which is an example of an object to be illuminated, is provided. In the present invention, it is sufficient that the LCD 20 is located below the light guide plate 14, and it goes without saying that the light guide plate 14 may be directly laminated on the LCD 20.

In the surface light emitter 1, the side shape of the light guide plate 14, that is, the shape of the light guide plate 14 as viewed from the axial direction of the fluorescent tube 10, is such that the thickness decreases from the base end surface 14e to the front end surface 14t. However, the shape is not limited to this, and as shown in FIG.
(A)), a wedge shape (FIG. 2 (B)) and an inverted ship bottom shape (hereinafter referred to as “reverse ship bottom shape”). However, if the light guide plate 14 has a flat plate shape when the surface roughening process described later has not been performed, light from the light source travels through the flat plate while repeating total reflection, and is emitted from the end face 14t of the flat plate. , Flat plate front and back 14r,
Since light is no longer emitted from 14s, it is not desirable to make the light guide plate 14 in a flat plate shape when the surface roughening process is not performed.

In the above-described surface light emitter 1, the surface or top surface 14s of the light guide plate 14 is roughened, but the roughened surface can brighten the image display by the LCD 20.

Such surface roughening can be performed after or at the time of molding the light guide plate 14. The roughened surface after molding can be obtained by subjecting the light guide plate itself to blasting, hot pressing or dot printing. It can be carried out. in this case,
In blasting and hot pressing, the material of the entire light guide plate is the same as the molding resin, but in dot printing,
It becomes a mixed material of the molding resin and the printing material, and the printing material (ink) is applied to the top surface of the light guide plate. Such ink has good adhesion to the light guide plate,
Those exhibiting the same optical characteristics as the surface roughening are preferable, and examples thereof include a medium-based ink.

On the other hand, the surface roughening during the molding is performed by blasting, etching, or the like in the cavity of the mold for molding the light guide plate.
Honing or embossing can be performed, and the light guide plate can be formed by using a mold cavity having such a roughened surface. In the surface roughening at the time of molding, after the mold cavity is once roughened to a desired degree, it is possible to obtain a light guide plate of almost the same quality by repeating resin molding according to an ordinary method. It is possible to carry out a surface roughening which is superior in homogeneity between products as compared with the surface roughening.

In the present invention, the above-mentioned roughening can be performed on the entire or a part of the top surface 14s of the light guide plate, and the degree of the roughening can be made uniform or changed. When the surface is uniformly roughened over the entire top surface, it is preferable to control the 10-point average roughness (Rz) on the top surface to 2.0 μm or less, and when Rz exceeds 2.0 μm,
This is not preferable because the transparency of the light guide plate is reduced and the illuminated object is difficult to see.

When the entire top surface is uniformly roughened,
The haze value between the top surface 14s and the bottom surface 14r is 15%
The following control is preferable. If the haze value exceeds 15%, the transparency of the light guide plate decreases, and the illuminated object becomes difficult to see, which is not preferable. The haze value is, for example, an automatic haze meter M manufactured by Tokyo Denshoku Co., Ltd.
ODEL TC-H III DPK and JIS
It can be measured between the top surface and the bottom surface of the light guide plate according to K7105.

On the other hand, as an example of changing the degree of the surface roughening, there is a mode in which the degree of the surface roughening becomes gentler as the distance from the fluorescent tube 10 increases. By changing the degree of the surface roughening in this way, uniform brightness over the entire surface of the light guide plate can be secured. That is, in the case where the degree of surface roughening is low, in the wedge shape, the vicinity of the lamp is dark and the distance becomes bright, but when the degree of surface roughening is changed in this way, uniform brightness is obtained over the entire light guide plate. Will be able to do it.

Next, the materials and the like of various components constituting the surface light emitter of the present invention will be described. First, as a linear light source, a fluorescent tube or the like can be exemplified, but a non-linear light source, for example, a light-emitting diode or a miniature light bulb may be linearly arranged, and the whole shape may be linear. Also, as the reflection means,
Reflectors made of white PET (polyethylene terephthalate) or aluminum or silver vapor-deposited film can be cited. When the light source is a fluorescent tube, the reflector has a cylindrical shape, and a light emitting diode or miniature bulb has a linear shape. When arranged in a cylindrical shape, a tubular reflector having a large number of concave surfaces on the inner wall surface may be used. Further, the light guide plate can be formed from acrylic resin, polycarbonate, polyester, polyvinyl chloride, polystyrene, or the like.

Although the surface illuminator of the present invention has the above-described configuration, for example, it is also possible to create an integrated mobile device by combining the surface illuminator 1 and the LCD 20.
However, in such a mobile device, the surface light emitter 1 is L
It is preferable to have a configuration that operates independently without interlocking with the CD 20. With this configuration, the surface light emitter 1 can be operated only when necessary, such as in a dark place or at night, and the power from a limited-capacity portable power supply can be used effectively. The operating time of the equipment can be substantially extended.

[0027]

The present invention will be described below in more detail with reference to examples and comparative examples.

(Example 1) A light guide plate made of acrylic resin and having a wedge-shaped side surface (length 80 x width 100 mm, base end 3.6)
mm, tip 1.2 mm). The light guide plate is roughened by etching honing performed on the mold cavity. The surface roughness and the like are as shown in Table 1. As a reflective LCD (black and white display),
A display panel (length 67 x width 79 x thickness 2.7 mm) of an alarm clock (trade name: DQ750, manufactured by Casio Corporation) was used. As a linear light source, a fluorescent tube (trade name: HMBVM2J () 110YS / AX, manufactured by Harrison Electric Co., Ltd .: trade name: HMBVM2J () 110YS / AX) with a tube luminance of 31,000 nits and a cylindrical reflector is a super reflector (3M Corporation). And product name), and the inverter is HIT-
082 D711 (trade name, manufactured by Harrison Electric Co., Ltd.).

The display panel described above was set on an angle changing jig, and a light guide plate was further laminated on the display panel so that the roughened surface of the light guide plate faced up. Also, as a luminance meter,
Using BM7 (trade name, manufactured by Topcon Corporation), the distance from the light guide plate was set to 50 mm. Next, the indoor fluorescent lamp was turned off, the fluorescent tube was turned on by the input voltage of 5.87 V, and the light guide plate was turned on. Further, the viewing angle was changed by an angle changing jig, and the luminance (Cd / m ² ), contrast (between white (background color of panel) / black (image) display) and optical characteristics at this time were measured. Table 1 shows the obtained results. In the table, the symbol “Tt” indicates the total light transmittance (%) and the symbol “Tt”.
"d" indicates a diffuse light transmittance (%), "Tp" indicates a parallel light transmittance (%), and "Haze" indicates a haze value (%), which are represented by the following formula: HAZE = Td / Tt * 100, Tp = Tt −Td. FIG. 3 shows the surface roughness.

(Examples 2 to 5) The same operation as in Example 1 was repeated except that the surface roughness of the light guide plate was changed as shown in Table 1. Table 1 shows the obtained results. FIG. 3 shows the surface roughness.

(Examples 6 to 10) The fluorescent tubes were turned off, the light guide plate was turned off, and two indoor fluorescent lamps installed on both sides of the light guide plate at a distance of 15 cm were turned on. Otherwise, the same operation as in Example 1 was repeated, and the obtained results are shown in Table 2. The light guide plates used in Example 6 were Example 1, Example 7 was Example 2, Example 8 was Example 3 and Example 9 was Example 4.
The tenth embodiment is the same as the fifth embodiment.

Comparative Example 1 The same operation as in Example 1 was repeated except that the indoor fluorescent lamp was turned on without using the light guide plate.
Table 2 shows the obtained results.

[0033]

[Table 1]

[0034]

[Table 2]

It is possible to determine the displayed image if the contrast is 2.0 or more. However, from Tables 1 and 2, in the above embodiment belonging to the present invention, it is possible to determine the displayed image within the range of 0 to 40 °.
0 or more, which clearly indicates that the image can be clearly distinguished.

As described above, the present invention has been described in detail with some embodiments and examples. However, the present invention is not limited to these, and various modifications can be made within the scope of the present invention. For example, the illuminated object is not limited to the reflection type LCD, but may be a book, a notebook, a card, and other articles.

[0037]

As described above, according to the present invention,
By using a light guide plate having a specific shape and a specific treatment, and using a surface light emitter that operates independently as required, it is possible to appropriately illuminate an object disposed below, and in particular, a reflection type LCD. And a light guide plate capable of realizing a good surface luminous body as the light source, and the surface luminous body.

[Brief description of the drawings]

FIG. 1 is a schematic side view showing an example of the surface light emitter of the present invention.

FIG. 2 is a schematic side view showing another shape of the light guide plate of the present invention.

FIG. 3 is a graph showing surface roughness.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 surface light-emitting body 10 fluorescent tube 12 reflector 14 light guide plate 14s top surface 14r bottom surface 14e base end surface 14t tip end surface

Claims (9)

[Claims] 1. A light guide plate used for a surface light emitter for illuminating an object to be illuminated disposed below, the side surface shape of which is viewed from the axial direction of a linear light source installed on the surface light emitter. A light guide plate having a wedge shape or an inverted ship bottom shape. 2. A light guide plate used for a surface light emitter for illuminating an object to be illuminated disposed below, the side surface shape of which is viewed from the axial direction of a linear light source installed on the surface light emitter. A light guide plate having a flat plate shape, a wedge shape, or an inverted ship bottom shape, and a whole or a part of a top surface thereof is roughened. 3. The light guide plate according to claim 2, wherein the roughening is performed by blasting, hot pressing, or dot printing after forming the light guide plate. 4. The light guide plate according to claim 2, wherein the roughening is performed by blasting, etching, or embossing applied to a mold cavity for molding the light guide plate. 5. The method according to claim 1, wherein the roughening is substantially uniform over the entire top surface, and a 10-point average roughness (Rz) on the top surface is 2.0 μm or less. The light guide plate according to any one of items 2 to 4. 6. The method according to claim 2, wherein the roughening is substantially uniform over the entire top surface, and a haze value between the top surface and the bottom surface is 15% or less. ~ 5
The light guide plate according to any one of the above items. 7. The method according to claim 2, wherein the degree of the surface roughening decreases as the distance from the linear light source increases.
4. The light guide plate according to any one of items 4 to 5. 8. A surface illuminator for illuminating an object to be illuminated disposed below, comprising: a linear light source; reflecting means surrounding the linear light source; and one end face close to the linear light source. A surface light-emitting body comprising: a light guide plate installed; wherein the light guide plate is the light guide plate according to claim 1. 9. The surface illuminator according to claim 8, wherein the object to be illuminated is a reflection type liquid crystal panel, and the surface illuminator operates independently of the reflection type liquid crystal panel.