JPH08221005A - Light transmission plate - Google Patents

Abstract

PURPOSE: To provide a light transmission plate capable of illuminating brightly and uniformly the whole display plate of a liquid crystal panel, etc., irrespective of distance from a light source. CONSTITUTION: In the light transmission plate 10 equipped with a light transmission plate main body 12 arranged on the back surface of the liquid crystal panel 11 and the light source 13 for illuminating this light transmission plate main body 12, the light transmission plate main body 12 is composed of a bundle of optical fibers 14, and rear end parts of the optical fibers 14 are made to be a light incident surface 19 of the light source 13, while tip parts of the optical fibers 14 are made to be a light emission surface 18 of the liquid crystal panel 11.

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 used for back lighting of a surface emitting illuminating plate such as a liquid crystal panel or an illuminated signboard.

[0002]

2. Description of the Related Art In recent years, a surface emitting display using a liquid crystal panel has been widely used in office automation equipment and the like, but a light guide plate is provided on the back surface of the liquid crystal panel in order to supplement the brightness of the display surface. Then, the method of illuminating from the rear side is adopted.

Conventionally, a transparent acrylic plate has been often used for this kind of light guide plate. The acrylic plate is illuminated by light incident from a light source, and a reflecting plate is arranged on the back surface of the acrylic plate to reflect the reflected light. The method of back-illuminating the liquid crystal panel is generally adopted. By the way, conventionally, various methods have been proposed for illuminating the entire liquid crystal panel brightly and uniformly. For example, as shown in FIG. 12, a bubble 2 is provided inside an acrylic plate 1 to make the brightness of incident light uniform so that the entire liquid crystal panel 3 is uniformly illuminated (Japanese Patent Laid-Open No. 4-29291), and FIG. As shown, there is known one using a polarizing filter 4 and a laminated light guide plate 5 so as to reduce the loss of incident light as much as possible (No. 4-129103, Jitsukaihei).

[0004]

However, in all of the above-mentioned conventional light guide plates, the light incident from the light source is passed through the acrylic plate and then radiated, so that the light passing through the acrylic plate is used. The longer the distance becomes, the weaker the light becomes, resulting in a difference in brightness between the position near the light source and the position far from the light source. Even when the size of the liquid crystal panel becomes large, the whole area is illuminated uniformly and brightly. It was difficult to do.

Therefore, an object of the present invention is to provide a light guide plate which can illuminate the entire display plate brightly and uniformly regardless of the distance from the light source.

[0006]

That is, in the light guide plate according to the present invention, the light guide plate main body disposed on the back surface of a display plate such as a liquid crystal panel is composed of a bundle of optical fibers, and the rear end portion of the optical fibers is formed. Is the light-entering surface of the light source, and the tip of the optical fiber is the light-emitting surface of the display plate.

[0007]

According to the above-mentioned means, the light from the light source is directly incident from the light incident surface of the optical fiber, and is totally reflected in the axial direction in the optical fiber while being emitted from the light emitting surface of the tip portion toward the display plate. Since the light is emitted, there is almost no loss of light, the light can be emitted regardless of the distance from the light source, and the entire display plate can be illuminated brightly and uniformly. Moreover, since the optical fiber is flexible, the degree of freedom in designing the optical fiber can be increased.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A light guide plate according to the present invention will be described in detail below with reference to the accompanying drawings. 1 to 4 show a first embodiment of a light guide plate according to the present invention. Among them, the light guide plate 1
Reference numeral 0 is composed of a light guide plate body 12 arranged on the back surface of a display plate such as a liquid crystal panel 11 and a light source 13 arranged on one side thereof. The light guide plate main body 12 is a bundle of many thin optical fibers 14 and is formed in a short size corresponding to the liquid crystal panel 11.

As means for bundling the optical fibers 14,
For example, as shown in FIGS. 3 and 4, first, each of the optical fibers 14 is fixed by an adhesive 15 to form a rectangular parallelepiped optical fiber block 16 in advance, and then the optical fiber block 16 is cut. A method of forming the light guide plate main body 12 by using the tip ends of the obliquely aligned optical fibers 14 cut along 17 as the light emitting surface 18, or a frame having a shape corresponding to the light guide plate main body 12 (not shown). ) Is used to store the optical fibers 14 therein and bundle them into a predetermined shape. When the above-mentioned adhesive 15 is used, it is necessary to select a material that does not affect the total reflection inside the optical fiber 14, and for example, a silicone resin adhesive is used.

Further, in this embodiment, since the light emitting surface 18 of the optical fiber 14 is arranged toward the liquid crystal panel 11,
The front surface side of the light guide plate body 12 is inclined so that the light emitting surfaces 18 of all the optical fibers 14 arranged are exposed to the liquid crystal panel 11 side. That is, the tip end of the light guide plate body 12 can be tilted by obliquely cutting the optical fiber block 16 by the method shown in FIG. 4, and the light emitting surface 18 of each optical fiber 14 can be projected. Since it is cut diagonally as shown in FIG. 3, it appears toward the liquid crystal panel 11 side. The rear end of the optical fiber 14 is provided as a light incident surface 19 toward the light source 13 to ensure effective incidence from the light source 13.

In this embodiment, as the light source 13, a cold cathode tube having a vertical width W of the light guide plate body 12 is used.

Therefore, in this embodiment, the light guide plate 1
When 0 is used, the light emitted from the light source 13
When the light is incident from the light incident surface 19 of the above, the light travels in the inside of the optical fiber 14 while repeating total reflection 20 in the axial direction, as shown in FIG. Then, the light is diffused from the light emitting surface 18 of the light guide plate body 12 to illuminate the back surface of the liquid crystal panel 11, but there is almost no light attenuation inside the optical fiber 14, so the light guide plate is irrespective of the distance from the light source 13. Body 12
In any place, the liquid crystal panel 11 can be illuminated uniformly and brightly with the same intensity.

As shown in FIG. 5, the optical fiber 1
By processing the light emitting surface 18 of No. 4 into an uneven shape by sandblasting or the like, the light is easily diffused, and the uniform irradiation of the light is further improved. Further, since the optical fiber 14 is excellent in flexibility, it is also easy to change the arrangement position of the light source 13 by bending the light incident surface 19 backward as shown in FIG.

FIGS. 7 and 8 show a second embodiment of the light guide plate according to the present invention. The light guide plate 30 according to this embodiment includes a light guide plate main body 32 having a recess 31 formed in the central portion on the back side and a light source 13 similar to the above, which is disposed in the recess 31. The main body 32 is formed by arranging two bundles of optical fibers 33 and 34 having a substantially triangular cross section. These optical fibers 33, 34
Are radially arranged so as to surround the light source 13, the light incident surfaces 35 and 36 of the optical fibers 33 and 34 are arranged toward the light source 13, and the light emitting surfaces 37 and 38 are liquid crystal panels. A flat surface that is arranged toward the liquid crystal panel 11 and is parallel to the liquid crystal panel 11 is formed.

In the bundle of the optical fibers 33 and 34 constituting the light guide plate body 32, each thin optical fiber 33 and 34 is formed into a block shape with an adhesive as in the above-mentioned embodiment. This is cut into a predetermined triangular shape, and the tip portions of the optical fibers 33 and 34 are cut obliquely, and the light emitting surface 3
It can be made by forming 7,38.

Therefore, according to this embodiment, like the previous embodiment, the liquid crystal panel 11 can be back-illuminated without attenuating the intensity of the light incident from the light source 13, and the optical fiber 33, Since it is possible to distribute 34 to the left and right, it is possible to facilitate the installation work and increase the number of optical fibers 33 and 34 to be installed, and it is particularly effective as a light guide plate for a large liquid crystal panel. Become.

As shown in FIG. 9, the optical fiber 3
By arranging the bundles of 3, 34 in the left and right opposite to the case of FIG. 7 and making the light from the light sources 13a, 13b incident on the respective light incident surfaces 35, 36, the irradiation from the light emitting surfaces 37, 38 can be performed. You can be stronger. In addition, the optical fibers 33, 34
As a means for arranging the bundles of the optical fibers to be distributed to the left and right, for example, as shown in FIG.
The light emitting surfaces 37 and 38 are bent back and forth by 0 degree so that the liquid crystal panel 11
The light guide plate main body 32 configured so as to face is also possible, and in this case, the liquid crystal panel 11 can be more effectively illuminated by the light emitted from the light emitting surfaces 37 and 38.
Furthermore, as shown in FIG.
The light guide plate main body 12 configured by a bundle of the optical fiber 39 and the light guide plate main body 40 in which the optical fibers 39 are arranged in the vertical direction and bundled are integrated by adhering their inclined surfaces to each other, and the light emitting surface 4 of the light guide plate main body 40.
It is also possible to make 1 face the liquid crystal panel 11. Also in this case, the light incident from the light incident surface 19 of the light guide plate body 12 is not attenuated on the way and the light emitting surface 41 of the light guide plate body 40 is not attenuated.
You can get effective lighting because it reaches up to.

In the above-described embodiment, the liquid crystal panel 11 is used as an example of the display plate, but the present invention is not limited to this.
The present invention is not limited to the above, and can be applied to a lighting signboard using a milky white acrylic plate or the like.

[0019]

As described above, according to the light guide plate of the present invention, the light from the light source is guided from the light incident surface into the optical fiber, and the inside thereof is totally reflected while the display plate is directly emitted from the light emitting surface. Since the back surface of the display is illuminated, there is almost no attenuation of the light guided from the light source, and the entire display plate can be illuminated brightly and uniformly regardless of the distance from the light source. Excellent effect for back lighting.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a light guide plate according to the present invention.

FIG. 2 is a sectional view taken along the line AA in FIG.

FIG. 3 is an enlarged view of a tip portion of an optical fiber.

FIG. 4 is a perspective view showing an optical fiber block.

FIG. 5 is an enlarged view of a tip portion of an optical fiber whose light emitting surface is processed into an uneven shape.

FIG. 6 is a cross-sectional view similar to FIG. 2 above, in which the arrangement position of the light source is changed.

FIG. 7 is a perspective view showing another embodiment of the light guide plate according to the present invention.

8 is a cross-sectional view taken along the line BB in FIG.

FIG. 9 is a cross-sectional view of a light guide plate when a pair of light sources is provided on the left and right sides of the light guide plate body.

FIG. 10 is a cross-sectional view of a light guide plate arranged such that a light emitting surface of an optical fiber is orthogonal to a display plate.

FIG. 11 is a cross-sectional view in which two light guide plates are combined so that a light emitting surface is orthogonal to a display plate.

FIG. 12 is a cross-sectional view showing an example of a conventional light guide plate.

FIG. 13 is a cross-sectional view showing another example of a conventional light guide plate.

[Explanation of symbols]

 10 light guide plate 11 liquid crystal panel 12 light guide plate body 13 light source 14 optical fiber 18 light emitting surface 19 light incident surface 30 light guide plate 32 light guide plate body 33 optical fiber 34 optical fiber 35 light incident surface 36 light incident surface 37 light emitting surface 38 light emitting surface 39 Optical fiber 40 Light guide plate body 41 Light emitting surface

Claims (1)

[Claims] 1. A light guide plate comprising a light guide plate main body disposed on the back surface of a display plate and a light source for illuminating the light guide plate main body, wherein the light guide plate main body is composed of a bundle of optical fibers, A light guide plate, wherein a rear end portion of the optical fiber is a light entrance surface of a light source and a front end portion of an optical fiber is a light emitting surface of a display plate.