JPH05196808A - Light diffusion plate and liquid crystal display unit constituted by using the same - Google Patents

Abstract

PURPOSE:To enhance transmittability of light, to suppress electric power consumption and to reduce weight by providing the curing resin of a shape having light refractiveness on a base material consisting of a transparent resin film. CONSTITUTION:The transparent resin film to constitute the base material 1 has preferably about >=80% and more particularly >=90% visible ray transmittance. The curing resin 2 of the shape having the light refractiveness is formed on th6 base material 1. There are no restrictions on the curing system of the curing resin 2 and the kind of the resin. A UV curing type, thermosetting type, etc., are all satisfactory and the resin is exemplified by an acrylic resin, epoxy resin, etc. Since the curing resin 2 on the base material 1 has the light refractiveness, the light entering from the rear surface of the base material 1 transmits the light diffusion plate and is refracted by the plate. The refracted light is made incident perpendicularly on a liquid crystal panel, by which the good diffusivity and high transmittability are obtd. Since the curing resin 2 has the light refractiveness in such a manner, the curing resin 2 is made into a semicircular, rugged or Fresnel lens shape.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light diffusing plate having excellent light transmittance and a liquid crystal display unit using the light diffusing plate.

[0002]

2. Description of the Related Art A liquid crystal display unit in a computer comprises a light source (cold-cathode tube), a reflection plate, a light guide plate, a diffusion plate, and a liquid crystal panel, and the light emitted from the light source is guided. After being guided to the entire unit by the light plate, it is made uniform by the diffusion plate and enters the liquid crystal panel.

In recent years, a liquid crystal display unit has been desired to have a brighter display with a higher contrast ratio, and this demand is particularly remarkable in the color liquid crystal display unit. In the case of color, the amount of light transmitted is reduced because it is masked with the three primary colors, and even the same light source requires about 10 times the amount of light as compared with monochrome.

Therefore, how to efficiently irradiate a liquid crystal panel with light, and in the case of color, how to transmit a large amount of light with the liquid crystal panel and the color filter as the same optical axis. .

However, polyethylene terephthalate (PE) mixed with a diffusing agent currently used as a diffusing plate is used.
The T) film has a low light transmittance of 90% or less and requires a strong light source. In addition, the embossed polycarbonate (PC) film has a transmittance of 1 for incident light.
Although it is close to 00%, it is necessary to emboss it in order to obtain light diffusivity, and it is impossible to make a thin product having a thickness of about 150 μm or less. Furthermore, light attenuation due to resin thickness (PC: approx. 9
0% / 1 mm), and there is a problem that the light transmittance decreases as the thickness increases.

[0006]

As a result of intensive studies to solve the above problems, the present inventors provided a curable resin having a photorefractive shape on a transparent resin film substrate. It has been found that, by doing so, it is possible to increase the light transmittance (increase the brightness), suppress power consumption, and reduce the weight (thinner).

The light diffusing plate of the present invention will be described in detail with reference to an example of the diffusing plate shown in FIG.

The transparent resin film serving as the substrate 1 is a film made of a resin having transparency and is not particularly limited, but the visible light transmittance (film thickness 2
00μ) is preferably about 80% or more, particularly preferably 90% or more. In addition, the film thickness is 1 to 200 μ in view of the moldability of the film itself, the light transmittance, and the thinning.
Particularly, 5 to 100 μ is preferable.

Although various resins can be mentioned, saturated polyester, polycarbonate, acrylic resin and the like are exemplified from the viewpoint of transparency and film moldability, and polyethylene terephthalate, polycarbonate and polymethylmethacrylate are particularly preferable.

There is no limitation on the curing method or the type of resin in the curable resin 2 formed on the substrate 1, and any of ionizing radiation curing type, ultraviolet curing type, heat curing type and chemical reaction type may be used. As the resin, acrylic resin, epoxy resin, polyester resin, urea melamine resin, urethane resin and the like can be mentioned. In particular, an ultraviolet curing type acrylic resin is particularly preferable in terms of dimensional accuracy.

An important point in the light diffusing plate of the present invention is that the curable resin 2 on the base material 1 has a photorefractive property. Light incident from the back surface of the base material 1 passes through the light diffusion plate and is refracted,
When the light enters the liquid crystal panel at a right angle, good diffusivity and high transparency are brought about.

Since the curable resin 2 has a photorefractive property (incident to the liquid crystal panel at a right angle), the curable resin 2 has a semi-circular shape as shown in FIGS. , A shape such as an uneven shape (a semicircle, a triangular pyramid, a polygonal pyramid such as a quadrangular pyramid), a washing plate shape (cross-sectional shape: triangular, trapezoidal).

The height of the curable resin 2 formed on the substrate 1 is not limited, but a height of 0.1 μ to 150 μ is preferable. If it is less than 0.1 μ, it is difficult to obtain a product having a good shape accuracy in terms of manufacturing. On the other hand, if it exceeds 150 μm, it takes a long time to cure the resin, and sufficient care must be taken to obtain an optically homogeneous product. It is preferably 5 to 100 μ.

Examples will be shown below, but the present invention is not limited to the examples.

Example 1 and Comparative Example 1 A 25 μm thick PET (polyethylene terephthalate) film was prepared, and UV (ultraviolet) having a refractive index of 1.47 was prepared on the PET film.
Curing type acrylic resin ink with a cross-section height of 20
A washing plate shape having an isosceles right triangle with a base of 40 μm and a base of 40 μ was formed. The obtained light diffusing plate is inserted between the liquid crystal unit and the light guide plate to form a liquid crystal display unit, and the brightness of the liquid crystal display (center of screen of liquid crystal display 3
I measured 0 cm above.

Similarly, a conventional PET light diffusing plate (1
As a result of measuring and comparing the luminance of the liquid crystal display unit using 00 μ), the liquid crystal display of the present invention is 5
It was confirmed to be effective, as it increased by 0% or more.

Example 2 and Comparative Example 2 A polycarbonate film having a thickness of 50 μm was prepared, and a UV curable acrylic resin ink having a refractive index of 1.43 was applied on the polycarbonate film to form an isosceles right triangle having a sectional height of 15 μm and a base of 30 μm. To form a washing plate shape.

By comparing with the liquid crystal display unit using the light diffusion plate of the present invention and the conventional embossed type polycarbonate film (200 μm thick) in the same manner as in Example 1, the sharpness of the screen in the product of the present invention, The superiority of contrast was confirmed.

[Brief description of drawings]

FIG. 1 is a perspective view of a light diffusion plate according to a first embodiment of the invention.

FIG. 2 is a perspective view of a light diffusion plate according to another embodiment of the present invention.

FIG. 3 is a perspective view of a light diffusion plate according to another embodiment of the present invention.

FIG. 4 is a top view of the light diffusion plate of the present invention shown in FIG.

FIG. 5 is a perspective view of a light diffusion plate according to another embodiment of the present invention.

FIG. 6 is a top view of the light diffusion plate of the present invention shown in FIG.

[Explanation of symbols]

 1 Transparent resin film 2 Curable resin

Claims (2)

[Claims] 1. A light diffusing plate comprising a transparent resin film substrate and a curable resin formed thereon, wherein the curable resin has a shape having a photorefractive property. 2. A transparent resin film substrate and a curable resin formed on the substrate, and the curable resin comprises a light diffusing plate having a photorefractive shape. Liquid crystal display unit.