JPS60250382A - Diffusion plate - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a diffuser plate mainly used in field effect liquid crystal display devices and the like.

<Prior Art> Conventional diffuser plates are known to be made of inorganic glass, or transparent polymeric materials such as polyester or polypropylene, with fine irregularities formed on one side to scatter light. . However, such a diffuser plate has weak light diffusing properties, is easily damaged, has poor self-supporting properties, and requires advanced technology to make the unevenness uniform in size.

As a method to solve this problem, the patent application
960 (Japanese Unexamined Patent Publication No. 57-88401) discloses the following method. That is, this is a method in which a pearl pigment that reflects and diffuses light is uniformly dispersed in a substrate, and a resin layer having light diffusing and transmitting properties is formed. According to this method, the above-mentioned drawbacks can be overcome.

<Problems to be solved by the invention> However, Japanese Patent Application No. 55-164960
7-88401), due to the characteristics of the pearl pigment, the transmission spectrum distribution shows a distribution like the solid line indicated by the symbol A in Figure 1, and as a result, when illuminating with white light from the back, the transmission The light was a brownish color, and when viewed as a liquid crystal display device, black characters were displayed on a brownish background, which was a drawback that the display was not necessarily beautiful.

An object of the present invention is to provide a novel diffuser plate that solves these problems.

<Structure of the Invention> The present invention comprises a resin layer having light diffusing and transmitting properties, and a substrate layer in which at least a pearl pigment and a fluorescent dye having an emission maximum wavelength in the range of 400 to 500 nm are uniformly dispersed and mixed in a transparent substance. It is a diffusion plate characterized by consisting of,
Furthermore, the substrate layer is added with a pearl pigment and a fluorescent dye to form 55
This diffuser plate has a layer in which a blue dye having a maximum absorption wavelength in the range of 0 to 700 nm is uniformly dispersed and mixed.

<Basic principle of the present invention> The diffuser plate having a substrate layer containing a pearl pigment disclosed in Japanese Patent Application No. 55-164960 shows a distribution like the solid line indicated by the symbol A in FIG. 1 in terms of spectroscopy. This shows that it transmits a lot of light in the system, and absorbs more blue light.

On the other hand, in order for white illumination light to pass through as white, the transmission spectrum of the diffuser plate must also be neutral, that is, without wavelength dependence.

Therefore, the present inventor investigated a method of supplementing blue light, which is absorbed more, and arrived at the present invention. In other words, it absorbs light of 400 nm or less, which is invisible to the human visual sense, and
The idea is to supplement blue light by using a fluorescent dye that emits light at 00 nm. According to the present invention, the transmission spectrum can be made closer to neutral, and the transmitted color can be made closer to white, as shown by the broken line indicated by the symbol B in FIG.

Furthermore, if only the fluorescent dye is used, the red transmitted light portion does not change, so in some cases, the whitening effect may still be insufficient. In this case, the inventor further considered absorbing a portion of the transmitted red light. That is, 550-7
00 nm absorbs a portion of the red transmitted light by further adding a dye having maximum absorption. This made it possible to make the transmitted light even closer to white light, as shown by the dashed-dotted line indicated by the symbol C in FIG.

<Example> In FIG. 2, reference numeral 1 represents a substrate layer, and reference numeral 2 represents a resin layer.

The resin N2 having light diffusing and transmitting properties used in carrying out the present invention can be formed of the following.

One of them is to coat one side (or both sides) of a transparent film (thickness 10 to 500 μm) made of optically transparent synthetic resin such as (meth)acrylic resin, acetate, polycarbonate, polyester, or polyurethane. The distance between the convex parts is 0.1 to 50 μm, the vertical depth from the top of the convex part to the bottom of the concave part is 0° to 10 μm, and the number of concave parts or convex parts is 1,000 to 100,000 pieces/m m'. unevenness 2
A translucent film or sheet formed by sanding or honing is used, and at least 10%
It is capable of transmitting light.

The other one is a synthetic resin with optical transparency (each of the above!
! @) and light-diffusing substances such as metal oxides such as aluminum oxide and titanium oxide, metal powders such as aluminum powder, tin powder, gold powder, and silver powder, rare earth oxides, alkaline earth metal oxides, calcium carbonate, and silicon dioxide. A translucent film (thickness: 10 to 500 .mu.m) is used, which is formed by uniformly dispersing and mixing so-called inorganic powders such as, for example, and forming into a film shape. The amount of the light-diffusing substance mixed varies depending on the particle size (approximately 0.01 to 30 μm), shape, reflective ability, etc. of the substance, but it is best to add it within the range of approximately 0.3 to 30% by weight. This is preferable because it can provide a resin film that has both the functions of light diffusion and light transmission, and has a light transmittance of at least 10%.

When fine irregularities 2a are formed on one or both sides of this resin film and a diffusion function is imparted to both the inside and the surface, diffusion is performed evenly and finely, and a preferable polarizing effect can be obtained.

Another type of resin film is an internal type in which light is diffused and transmitted through the structure constituting the resin film, and is made by foaming the optically transparent synthetic resin, such as polystyrene, using a conventional method (foaming ratio: 1.5 ~10 times), and then subjected to processing operations such as heating and pressurization and/or heating stretching, and finally the internal structure is made into a state of agglomeration of flat cells with a diameter of about 0.3 to 2 mm. Approximately 0.03-1.
0 mm and a light transmittance of at least 10%, paper made using natural and/or synthetic resin fiber threads, non-woven fabric made by intertwining fiber threads, etc. The thickness is 0.03 to 1.5 m and consists of a fibrous body with countless fine voids between the fibers.
A translucent film-like material having a light transmittance of at least 1.0% with m is used, and a film-like material that utilizes a whitening phenomenon caused by mutual compatibility between polymers by a polymer blending method is used.

Transparent substances such as (meth)acrylic resin, polycarbonate, Polymer materials such as acetate, polyester, polystyrene, polyurethane, or transparent substances such as glass are used. Pearl pigments include fish scale foil, basic lead carbonate, bismuth acid chloride,
Pearl pigments such as titanium dioxide coated mica are used.

Therefore, pearl pigments are produced by opening and pulverizing muscovite, which has excellent colorless transparency, to have an average wavelength diameter of about 3 to 150 μm and a thickness of 1/10 or less of the diameter, preferably 1/15 to 1/100. scaly mica with a grain size of about 0.0 on the surface.
It is obtained by coating titanium dioxide fine particles of 3 to 0.08 in the form of a hydrate and roasting to form a thin titanium coating. The titanium dioxide-coated mica obtained in this way is used because the mica (pearl pigment) is arranged within the film layer to create a layered structure, and the incident light is regularly reflected multiple times by the arranged scale-like crystals. This is preferable because it gives a soft and deep luster.

The amount of pearl pigment added varies depending on the size, shape, material, etc. of the pigment, but can be added in a range of about 5 to 60% by weight. If it is less than 5% by weight, the light transmittance is good, but the reflection and diffusion effects are insufficient, and if it is more than 60% by weight, the diffusion effect is insufficient and the transmittance is decreased, which is not preferable.

Any type of fluorescent dye may be used as long as it has a maximum emission wavelength of 400 to 500 nm and is uniformly dissolved or dispersed in a transparent substance, such as C and I.

Fluorescent, Brightening, Agent-16
3, same 164. Same 172. Same 91 and 2.5
Bis, (5'tertiarybutylbenzooxazolyl(2))thiophene, etc. are used.

The amount of fluorescent dye added varies depending on the luminescence intensity performance of the dye, but can be added in the range of about 0.01 to 15% by weight. If it is less than 0.01% by weight, it will not be possible to generate enough light to change the color tone of transmitted light, and if it is more than 15% by weight, it will generally lack solubility for transparent substances, often causing dye precipitation, and it will also be economical. It's not desirable either.

Any type of blue dye may be used as long as it has a maximum absorption wavelength of 550 to 700 nm and can be uniformly melted or dispersed in a transparent material, such as C and T.

Solvent, Blue-25, Same 35. Same 36゜ Same 55. Examples include dyes having the same structure as 73 or the following structural formula.

The amount of the blue dye added varies depending on the absorption strength performance of the dye, but can be added in the range of about 0.001 to 5% by weight. If the amount added is too small, the desired characteristics cannot be achieved, and if it is too large, the transmitted light becomes too blue, so it is necessary to set the amount appropriately.

The resin layer 2 having light diffusion and transmittance is integrated with the substrate layer 1 in advance in the form of a film (thickness approximately 0.005 to 5 m/m).
On the other hand, a pearl pigment, a fluorescent dye, or a mixture in which a pearl pigment, a fluorescent dye, and a blue dye are uniformly dispersed and mixed in a transparent material is formed into a film (thickness of about 5 to 100 mm).
The resin layer film may be attached to the substrate N1, or a transparent substance having a composition that can be applied and cured by a polymerization reaction is selected, and a pearl pigment is added therein.

The resin layer film may be formed by uniformly dispersing and mixing a fluorescent dye, a pearl pigment, a fluorescent dye, or a blue dye, coating the resin layer film, and drying it.

<Effects> According to the present invention, the reflection, diffusion, and transmission of light can be easily and easily controlled by adding pearl pigments, and the reflection, diffusion, etc. It has the characteristic that the various effects of the above do not decrease, and it also has the characteristic that a soft and deep luster can be obtained by using titanium dioxide-coated mica, which is the surface of scaly mica coated with titanium dioxide, as a pearl pigment. . Furthermore, since the transmitted light is neutralized by a fluorescent dye or a fluorescent dye and a blue dye, if the diffuser plate of the present invention is used in a liquid crystal display device using a light emitter, the original color tone of the light emitter will be lost. Therefore, a bright and beautiful display can be obtained.

Moreover, since it has a resin layer that has light diffusion and transparency,
Since it has excellent self-supporting properties as a diffuser plate, it has the advantage of easy mounting work and less damage.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the spectral wavelength and spectral transmittance (%) of a diffuser plate, and FIG. 2 is a sectional view of the diffuser plate showing an example. 1-Substrate layer 2-Resin layer A-Spectral lines B and C of conventional diffuser plate-1 Spectral lines according to the present invention Patent applicant
Nitto Electric Industry Co., Ltd. Agent Patent Attorney Nishi 1) Arata

Claims (1)

[Claims] A resin layer having +1.1 light diffusion transmittance, and a substrate layer in which at least a pearl pigment and a fluorescent dye having an emission maximum wavelength in the range of 400 to 500 nm are uniformly dispersed and mixed in a transparent substance. A diffuser plate characterized by comprising: (2) The diffuser plate according to claim 1, wherein the substrate layer includes a pearl pigment, a fluorescent dye, and a blue dye having a maximum absorption wavelength in the range of 550 to 700 nm, which is uniformly dispersed and mixed. (3) The diffuser plate according to claim 1 or 2, wherein the pearl pigment is formed by coating the surface of scale-like mica with titanium dioxide.