JPH08327801A - Conductive antireflection plate and image display device using the same - Google Patents

Abstract

PURPOSE: To increase the adhesion property of a conductive transparent thin film to a transparent substrate, to obtain good durability and to obtain a low reflectance for a wide wavelength range. CONSTITUTION: The conductive antireflection plate is produced by successively laminating a first transparent thin film 2, a conductive second transparent thin film 3, a third transparent thin film 4, a fourth transparent thin film 5, and a fifth transparent thin film 6 on a transparent substrate l in such a manner that the refractive indices n1 , n2 , n3 , n4 , n5 of the first, second, third, fourth and fifth transparent thin films 2, 3, 4, 5, respectively, satisfy the relation of n1 <n2 , n3 ,<2 , 2.05<=n4 <=2.5, n5 <=n1 and that the film thickness of the second transparent thin film 3 is <=50nm. Moreover, the first, third and fifth transparent thin films 2, 4, 6, respectively, are preferably made of silicon dioxide. The second transparent thin film 3 is preferably made of a mixture of indium oxide and tin oxide. The obtd. conductive antireflection plate may be adhered to the front panel of a cathode ray tube.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive antireflection plate in which a conductive transparent thin film and a plurality of transparent thin films having different refractive indexes are formed on a transparent substrate, and an image display device using the same. Specifically, by controlling the refractive index and film thickness of the transparent thin films, the adhesion of the conductive transparent thin films to the transparent substrate is enhanced, and the conductive anti-reflection which realizes the low reflectance in a wide wavelength range. The present invention relates to a plate and a video display device using the plate.

[0002]

2. Description of the Related Art In a cathode ray tube (hereinafter referred to as CRT) used in a computer display,
Light incident from the outside is reflected on the surface of the front panel on which an image is displayed, which makes it difficult to see the image formed on the front panel, and discharges between the human body and others due to charging during operation of the computer. To prevent this, a conductive antireflection film is provided on the surface of the front panel.

The conductive antireflection film is a CRT.
CRT front panel by directly arranging it on the front panel surface of CRT, or by forming a conductive antireflection film on a glass panel of the same shape as the front panel of CRT and arranging this on the front panel of CRT. It is provided in.

However, when the conductive antireflection film is provided on the front panel of the CRT as described above, the antireflection performance is sufficient, but a large-scale film forming apparatus is required and the manufacturing cost becomes high. This causes inconveniences such as an increase in the weight of itself. It is also proposed to install a panel-shaped filter having a conductive antireflection film between the CRT and the human body to prevent reflection on the front panel surface of the CRT and prevent discharge between the human body and the like. However, in this method, the reflectance of the front panel of the CRT itself is not changed, so that the light amount on the front panel is reduced or C
Since it is impossible to prevent the surface of the front panel of the RT from being charged, it is not possible to prevent dust and the like from adhering to the surface of the front panel, and as a result, the visibility is deteriorated.

[0005]

Therefore, a conductive antireflection plate having a conductive antireflection film formed on a panel or film made of plastic is formed and attached to the front panel surface of a CRT at low cost. There has also been proposed a method of preventing reflection on the front panel surface of the CRT and preventing discharge from the human body without increasing the weight of the CRT itself.

However, when forming a thin film on a panel or film made of plastic, it is necessary to form the thin film at a relatively low temperature in consideration of the heat resistance of the plastic, and the constituent material of the conductive antireflection film is limited. Inconvenience occurs. That is, for example, Japanese Patent Publication 4-1544
Japanese Patent Publication No. 3 and Japanese Patent Publication No. 4-14761 disclose that a thin film containing MgF ₂ is formed as a conductive antireflection film on a transparent substrate made of glass to form a conductive antireflection plate. Since MgF ₂ causes cracks when it is formed at a low temperature, it is necessary to form it at a high temperature, and it should be formed on a transparent substrate made of plastic as one component of a conductive antireflection film. Is impossible.

A thin film made of a mixture of indium oxide and tin oxide (hereinafter referred to as ITO) is also applicable as a conductive transparent thin film having a high refractive index, but this ITO has an adhesive property with a plastic. Poorly, it will cause deterioration of durability of the conductive antireflection plate formed. further,
If the above ITO thin film is used as the uppermost layer, disadvantages such as a sufficiently low reflectance cannot be obtained.

Therefore, the present invention has been proposed in view of the conventional circumstances, and enhances the adhesion of a conductive transparent thin film to a transparent substrate, has good durability, and has low reflection over a wide wavelength range. It is an object of the present invention to provide a conductive antireflection plate having a high index and an image display device using the same.

[0009]

In order to solve the above-mentioned problems, a conductive antireflection plate of the present invention comprises a first transparent thin film, a second transparent thin film having conductivity, and a third transparent thin film on a transparent substrate. A transparent thin film, a fourth transparent thin film, and a fifth transparent thin film are sequentially stacked, and the first transparent thin film has a refractive index of n ₁ , the second transparent thin film has a refractive index of n ₂ , and the third transparent thin film has a refractive index of n ₂ . Refractive index n ₃ , fourth
Where n ₁ <n ₂ , n ₃ <n ₂ , 2.05, where n _{4 is} the refractive index of the transparent thin film and n ₅ is the refractive index of the fifth transparent thin film.
It is characterized in that the relationship of ≦ n ₄ ≦ 2.5 and n ₅ ≦ n ₁ is satisfied, and the film thickness of the second transparent thin film is 50 nm or less.

The film thickness of the second transparent thin film is 50 n.
If it is thicker than m, it is difficult to obtain sufficient antireflection characteristics. In the conductive antireflection plate of the present invention, the first
The transparent thin film, the third transparent thin film, and the fifth transparent thin film are preferably made of silicon dioxide.

Further, in the conductive antireflection film of the present invention, the second transparent thin film is preferably made of a mixture of indium oxide and tin oxide. Furthermore, the image display device may be constructed by attaching the conductive antireflection plate of the present invention to the front panel of the cathode ray tube.

[0012]

In the conductive antireflection plate of the present invention, the transparent substrate
First transparent thin film on the plate, second transparent thin film having conductivity
Film, third transparent thin film, fourth transparent thin film, fifth transparent thin film
Are sequentially stacked, and the refractive index of the first transparent thin film is n.₁ ,
Let the refractive index of the second transparent thin film be n₂ , Refraction of the third transparent thin film
Rate n₃ , The refractive index of the fourth transparent thin film is n_Four , Fifth transparent
The refractive index of the thin film is n_Five And then n₁ <N₂ , N₃ <
n₂ , 2.05 ≦ n _Four ≤2.5, n_Five ≤n₁ Full of relationships
In addition, the thickness of the second transparent thin film is 50 nm or less
Therefore, it exhibits a sufficient antireflection property. Also,
Since the transparent thin film of 4 has a high refractive index, it can cover a wide range of wavelengths.
It exhibits low reflectance over time. Furthermore, transparent substrate and conductivity
The second transparent thin film, which will be the transparent thin film of
Since the first transparent thin film having excellent wearability is arranged,
Adhesion of the second transparent thin film to the substrate is good.
It

Further, when the conductive antireflection plate of the present invention is attached to the front panel of the cathode ray tube to constitute the image display device, the film thickness of the second transparent thin film of the conductive antireflection plate is secured. Therefore, an image display device having a sufficient antistatic effect and electromagnetic shielding effect is constructed.

[0014]

EXAMPLES Specific examples of the present invention will be described below based on experimental results. That is, under various conditions, a first transparent thin film 2, a conductive second transparent thin film 3, a third transparent thin film 4, a fourth transparent thin film 4, a fourth transparent thin film 4, and a fourth transparent thin film 4 on a transparent substrate 1 as shown in FIG.
The transparent thin film 5 and the fifth transparent thin film 6 were sequentially laminated to form a conductive antireflection plate, and the reflection characteristics of these conductive antireflection plates were investigated.

First, a 20-nm-thick aluminum oxide (hereinafter referred to as Al ₂ O ₃ ) film is formed as a first transparent thin film 2 on a film-like transparent substrate 1 made of polyethylene terephthalate (hereinafter referred to as PET). ), A thin film made of ITO having a thickness of 27 nm is formed as the second transparent thin film 3, and a thin film made of SiO _{2 having a} thickness of 20 nm is formed as the third transparent thin film 4. As the transparent thin film 5, a thin film made of titanium dioxide (hereinafter referred to as TiO ₂ ) having a film thickness of 103 nm is formed.
As a transparent thin film 6 of silicon dioxide having a film thickness of 88 nm (hereinafter,
It is called SiO ₂ . Was formed into a conductive antireflection plate sample 1.

At this time, the refractive index of the first transparent thin film 2 is n ₁ , the refractive index of the second transparent thin film 3 is n ₂ , the refractive index of the third transparent thin film 4 is n ₃ , and the fourth transparent thin film. If the refractive index of the thin film 5 is n ₄ and the refractive index of the fifth transparent thin film 6 is n ₅ , then n ₁
= 1.62, n ₂ = 2.0, n ₃ = 1.45, n ₄ =
2.4, and n ₅ = 1.45.

Next, as in the case of the conductive antireflection plate sample 1, the first transparent thin film 2 is formed on the transparent substrate 1 made of PET.
As to form a SiO ₂ film having a film thickness of 76 nm, a second transparent thin film 3 to form an ITO thin film having a film thickness of 24 nm, a SiO ₂ film having a film thickness of 34nm was formed as a third transparent thin film 4, the fourth TiO with a thickness of 104 nm as the transparent thin film 5
₂ thin films are formed, and the film thickness is 86 nm as the fifth transparent thin film 6.
Conductive antireflection plate sample 2 by forming a SiO ₂ thin film of
Was manufactured.

At this time, the refractive index of the first transparent thin film 2 is n ₁ , the refractive index of the second transparent thin film 3 is n ₂ , the refractive index of the third transparent thin film 4 is n ₃ , and the fourth transparent thin film. If the refractive index of the thin film 5 is n ₄ and the refractive index of the fifth transparent thin film 6 is n ₅ , then n ₁
= 1.45, n ₂ = 2.0, n ₃ = 1.45, n ₄ =
2.0, n ₅ = 1.45.

Next, as in the case of the conductive antireflection plate sample 1, the first transparent thin film 2 is formed on the transparent substrate 1 made of PET.
As to form a SiO ₂ film having a film thickness of 61 nm, a second transparent thin film 3 to form an ITO thin film having a film thickness of 20 nm, the Al ₂ O ₃ thin film having a film thickness of 44nm was formed as a third transparent thin film 4, the 4 as a transparent thin film 5 having a thickness of 103 nm Ti
An O ₂ thin film is formed to form a fifth transparent thin film 6 having a film thickness of 87 n.
A conductive antireflection plate sample 3 was manufactured by forming a SiO ₂ thin film of m.

At this time, the refractive index of the first transparent thin film 2 is n ₁ , the refractive index of the second transparent thin film 3 is n ₂ , the refractive index of the third transparent thin film 4 is n ₃ , and the fourth transparent thin film. If the refractive index of the thin film 5 is n ₄ and the refractive index of the fifth transparent thin film 6 is n ₅ , then n ₁
= 1.45, n ₂ = 2.0, n ₃ = 1.62, n ₄ =
2.4, and n ₅ = 1.45.

The conductive antireflection plate samples 1 to
In the production of No. 3, each thin film is formed by sputtering each thin film constituent material, and the above materials can be formed at a low temperature. Further, each thin film can be formed by a usual vapor deposition method or an ion plating method in addition to the above-mentioned sputtering method. Furthermore, in the above-mentioned conductive antireflection plate samples 1 to 3, PET was used as the transparent substrate 1.
However, the film is not limited to this, and an acrylic resin, a cellulose resin, or the like is exemplified.

At this time, the conductive antireflection plate samples 1 to
3, the refractive index of the first transparent thin film 2 is n ₁ ,
The refractive index of the transparent thin film 3 is n ₂ , the refractive index of the third transparent thin film 4 is n ₃ , the refractive index of the fourth transparent thin film 5 is n ₄ , and the refractive index of the fifth transparent thin film 6 is n ₅ . Then n ₁ <n ₂ , n
The relationship of ₃ <n ₂ , 2.05 ≤ n ₄ ≤ 2.5, n ₅ ≤ n ₁ is satisfied.

For comparison, a conventional transparent substrate made of glass and having a plurality of thin films formed thereon was prepared.
Incidentally, a thin film made of two materials of high and low refractive index with an equivalent film as the thin film, using a TiO ₂ as a high refractive material, SiO ₂ as a low refractive index material
It was used. That is, on a transparent substrate made of glass, a SiO ₂ thin film having a thickness of 40 nm is formed as a first transparent thin film, a TiO ₂ thin film having a thickness of 12 nm is formed as a second transparent thin film, and a film is formed as a third transparent thin film. 40nm thick SiO
₂ thin films are formed, and the film thickness is 114 nm as the fourth transparent thin film.
TiO ₂ thin film is formed as a fifth transparent thin film with a film thickness of 8
A 9 nm SiO ₂ thin film was formed to form a conductive antireflection plate sample 4.

Also in the production of the conductive antireflection plate sample 4, each thin film is formed by sputtering each thin film constituent material. Next, the spectral reflectance of the conductive antireflection plate samples 1 to 4 was investigated.
A halogen lamp was used as a light source, and the light was incident on the transparent substrate side from the air with an incident angle of 5 deg. At this time, the back surface was sanded so as not to be affected by the transparent substrate. The results of the spectral reflectance of the conductive antireflection plate samples 1 to 4 are shown in FIGS. 2 to 5, respectively.

From the results of FIGS. 2 to 5, the spectral reflectances of the conductive antireflection plate samples 1 to 3 have the same characteristics as those of the conductive antireflection plate sample 4 which has been conventionally used, and the sufficient reflectance is obtained. It was confirmed to have preventive performance. Also, FIG.
From the results of FIG. 4, the conductive antireflection plate samples 1 to 3 show low reflectance over a wide range of wavelength regions, and the wavelength region includes most of the visible region, so that the antireflection effect is extremely high. It was also confirmed to be high. This is because the refractive index of the first transparent thin film 2 is n ₁ , the refractive index of the second transparent thin film 3 is n ₂ , and the refractive index of the third transparent thin film 4 is n 1.
_3, refractive index n ₄ of the fourth transparent thin film 5, when the refractive index of the fifth transparent thin film 6 was _{n 5, n 1 <n 2} , n 3 <n
₂ , 2.05 ≦ n ₄ ≦ 2.5, n ₅ ≦ n ₁ , and the refractive index of the fourth transparent thin film 5 is low.
It is considered that the thickness of the transparent thin film 3 is 50 nm or less.

Further, in the samples 1 to 3 of the electroconductive prevention plates, the first transparent material having a low refractive index and excellent adhesion was provided between the transparent substrate 1 and the second transparent thin film 3 serving as a conductive transparent thin film. Since the thin film 2 is arranged, the second transparent thin film 3
Adhesion to the transparent substrate becomes good, and durability becomes good.

Furthermore, in the conductive antireflection plate samples 1 to 3, the film thickness of the second transparent thin film 3 is ensured, so that a sufficient antistatic effect is exhibited, and the conductive antireflection film as described above is obtained. In the image display device in which the plate samples 1 to 3 are attached to the surface of the front panel of the CRT, although the front panel of the CRT is relatively easy to generate electrostatic charge,
By dropping the conductive film to the ground, a sufficient antistatic effect and electromagnetic shielding effect can be obtained.

[0028]

As is apparent from the above description, in the conductive antireflection plate of the present invention, the first transparent thin film, the conductive second transparent thin film, and the third transparent thin film are formed on the transparent substrate. A thin film, a fourth transparent thin film, and a fifth transparent thin film are sequentially stacked, and the refractive index of the first transparent thin film is n ₁ , the refractive index of the second transparent thin film is n ₂ , and the third transparent thin film is refracted. Rate n ₃ , fourth
Where n ₁ <n ₂ , n ₃ <n ₂ , 2.05, where n _{4 is} the refractive index of the transparent thin film and n ₅ is the refractive index of the fifth transparent thin film.
Satisfying the antireflection property because the relationship of ≦ n ₄ ≦ 2.5 and n ₅ ≦ n ₁ is satisfied and the film thickness of the second transparent thin film is 50 nm or less. Moreover, since the fourth transparent thin film has a high refractive index, it exhibits a low reflectance over a wide wavelength range. Furthermore, since the first transparent thin film having a low refractive index and excellent adhesiveness is arranged between the transparent substrate and the second transparent thin film which is a conductive transparent thin film, Adhesion to the substrate is good, and durability is also good.

When the conductive antireflection plate of the present invention is attached to the front panel of the cathode ray tube to form an image display device, the thickness of the second transparent thin film of the conductive antireflection plate is secured. Therefore, an image display device having a sufficient antistatic effect and electromagnetic shielding effect is constructed.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a conductive antireflection plate.

FIG. 2 is a characteristic diagram showing a spectral reflectance of a conductive antireflection plate sample 1.

FIG. 3 is a characteristic diagram showing a spectral reflectance of a conductive antireflection plate sample 2.

FIG. 4 is a characteristic diagram showing a spectral reflectance of a conductive antireflection plate sample 3.

5 is a characteristic diagram showing a spectral reflectance of a conductive antireflection plate sample 4. FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transparent substrate 2 1st transparent thin film 3 2nd transparent thin film 4 3rd transparent thin film 5 4th transparent thin film 6 5th transparent thin film

Claims (4)

[Claims] 1. A first transparent thin film, a second transparent thin film having conductivity, a third transparent thin film, a fourth transparent thin film, and a fifth transparent thin film are sequentially laminated on a transparent substrate to form a first transparent thin film. The transparent thin film has a refractive index n ₁ , the second transparent thin film has a refractive index n ₂ , the third transparent thin film has a refractive index n ₃ , the fourth transparent thin film has a refractive index n ₄ , and the fifth transparent When the refractive index of the thin film is n ₅ , n ₁ <n ₂ , n ₃ <n ₂ , 2.05 ≦ n ₄
A conductive antireflection plate satisfying the relations of ≦ 2.5 and n ₅ ≦ n ₁ and having a film thickness of the second transparent thin film of 50 nm or less. 2. A first transparent thin film, a third transparent thin film, and a fifth transparent thin film.
2. The conductive antireflection plate according to claim 1, wherein the transparent thin film is made of silicon dioxide. 3. The conductive antireflection plate according to claim 1, wherein the second transparent thin film is made of a mixture of indium oxide and tin oxide. 4. An image display device comprising the conductive antireflection plate according to claim 1 attached to a front panel of a cathode ray tube.