JPH0737533A - Panel for cathode-ray tube - Google Patents

Abstract

PURPOSE:To improve electromagnetic wave shield by laminating plurality of materials having a specific film thickness and refractive index, so as to decrease a reflection factor over a wide band. CONSTITUTION:In an external surface of a panel glass 10, a mixed thin film 11 of TiO2 and SiO2 is formed as the first layer, and a thin film 12 of SnO2 is formed as the second layer. Further as the third layer, an SiO2 thin film 13 is formed, and when successively laminated the thin films 11, 12, 13, when heat treated a panel, an alkali component appearing in its surface can be prevented from being generated. Here, a film thickness is made 809Angstrom for the thin film 11, 688Angstrom for the thin film 12 and 942Angstrom for the thin film 13, and a refractive index is made 1.7 for the thin film 11, 2.0 for the thin film 12 and 1.46 for the thin film 13. Then, a panel has excellent electromagnetic wave shieldability and reflection preventability, so as to provide a low refractive index over a wide band. In this way, the image are prevented from giving fatige to a viewer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cathode ray tube panel having a high electromagnetic wave shielding property and antireflection property on its outer surface.

[0002]

2. Description of the Related Art A cathode ray tube is composed of a panel on which an image is displayed, and a funnel and a neck which are formed behind the panel.

In a cathode ray tube, an electron beam emitted from an electron gun mounted in a neck tube is deflected by a deflection coil attached around a funnel. Particularly, when an unnecessary electromagnetic wave generated from this deflection coil leaks, the cathode ray tube There is a risk that other electronic devices around the tube may malfunction or the human body may be adversely affected. Therefore, in the conventional cathode ray tube, a conductive film such as tin oxide having conductivity is formed on the outer surface of the panel in order to impart the property of shielding electromagnetic waves.

However, in the conventional cathode ray tube panel, the sheet resistance (resistance value per square) of the conductive film formed on the outer surface of the panel is 1 × 10 ⁶ Ω /
Since it is as high as □ or more, it has low conductivity and is insufficient to completely shield unwanted electromagnetic waves. In addition, the conductive film formed on the conventional panel has a mirror-finished surface, and the tin oxide film has a higher refractive index than the panel glass. If the thickness is increased, there is a problem that the surface reflection is large and the image is difficult to see.

Therefore, it has been proposed to suppress the surface reflection of light by forming a transparent conductive film on the panel surface and then forming an antireflection film on it.
A cathode ray tube is formed by forming a transparent conductive film made of SnO ₂ having a film thickness of ₂₀₀ to 400 Å on the outer surface of a panel by a CVD method, and further forming an antireflection film made of SiO ₂ thereon by a spin coating method. Proposed.

[0006]

However, such a cathode ray tube has a considerably low reflectance in a narrow wavelength region near 550 nm, but has a high reflectance in other visible regions, particularly a low reflectance around 400 nm. In the wavelength region, the reflectance is higher than that of a panel having no film formed on the outer surface, and it is still insufficient to solve the problem that an image is hard to see. In addition, such a panel having a low reflectance only in a narrow wavelength range has a drawback that it tends to give a feeling of fatigue because it is perceived by the viewer as a dark color.

The thickness of SnO ₂ is 200 to 400Å
Since it is thin, the surface resistance of the transparent conductive film is as high as 1 × 10 ⁶ Ω / □, which is insufficient to shield unnecessary electromagnetic waves.

Therefore, an object of the present invention is to have an excellent electromagnetic wave shielding property and a low reflectance over a wide wavelength range (hereinafter, referred to as a wide band), which gives a viewer a feeling of fatigue. It is to provide a panel for a cathode ray tube.

[0009]

The present invention has been made in view of the above problems and objects, and a refractive index between the refractive index of glass and the refractive index of SnO ₂ is formed in the first layer on the outer surface side. A thin film made of a material having a refractive index is formed, and SnO ₂ is formed on the second layer.
A cathode ray tube panel, wherein a thin film is formed, and a thin film made of a material having a refractive index lower than that of the first layer is formed as a third layer.

The first thin film is TiO ₂ and SiO.
It is characterized in that it is made of a mixture of ₂ and the thin film of the third layer is made of SiO ₂ .

Further, the second thin film is formed by the CVD method and has a film thickness of 500 Å or more and a sheet resistance of 3 × 10 ³ Ω or less.

[0012]

In the present invention, the second SnO ₂ film used as the transparent conductive film has a refractive index (nd) of 2.0 and is cheaper and more stable in performance than the In ₂ O ₃ thin film. It is characterized by being

Further, in the present invention, a thin film having a refractive index between the refractive index of glass and the refractive index of the SnO ₂ thin film of the second layer is formed as the thin film of the first layer, and the thin film of the third layer is formed. Since a thin film having a refractive index lower than that of the first layer is formed as the thin film of, the low reflectance can be obtained over a wide band.

The material of the first thin film, that is, the thin film having a refractive index between the refractive index of glass (refractive index = 1.536) and the refractive index of SnO ₂ is TiO ₂ , ZrO.
₂ , Ta ₂ O ₅ , ZnS, a mixture of CeO ₂ and SiO ₂ , etc. can be used, and SiO ₂ , MgF ₂ etc. can be used as the material of the third layer thin film, but the reflection of the panel Considering prevention performance and cost, T is the first layer.
a thin film of a mixture of iO ₂ and SiO ₂ (refractive index = 1.7),
It is most desirable to use a thin film of SiO ₂ (refractive index = 1.46) as the third layer.
The spin coating method, the dip coating method, or the spray coating method is suitable.

The CVD method for forming SnO ₂ is cheaper than other coating methods and suitable for mass production. Usually, when a thin film of SnO ₂ is directly formed on the surface of the panel by the CVD method, the alkali component in the glass is exposed on the surface of the panel by the heat treatment of the panel, so that 3 × 10 ³ Ω / □ is obtained.
In order to obtain the resistance value of, the film thickness must be considerably increased. However, by forming the thin film of the first layer and then forming the SnO ₂ thin film on it, it becomes possible to prevent alkaline components from appearing on the surface of the panel.
Even if the O ₂ film is thin, a resistance value of 3 × 10 ³ Ω / □ or less can be stably obtained. Further, a small amount of Sb ₂ O ₃ can be added to the SnO ₂ forming the _second thin film for the purpose of lowering the resistance value.

[0016]

The cathode ray tube panel of the present invention will be described in detail below with reference to examples.

(Example) FIG. 1 is a vertical sectional view of a panel for a cathode ray tube according to the present invention.

This panel glass 10 (refractive index 1.53
On the outer surface of 6), a mixed thin film (refractive index 1.7) of TiO ₂ and SiO ₂ having a film thickness of 809Å is formed as the first layer, and a film thickness of 688Å is formed as the second layer. An SiO ₂ thin film 1 having a SnO ₂ thin film 12 (refractive index of 2.0) formed thereon and having a film thickness of 942 Å as a third layer.
3 (refractive index 1.46) is formed.

Each thin film was formed on the outer surface of the panel glass 10 by the following method.

First, the panel glass is washed, dried, and rotated in a preheated state, while TiO ₂ and Si
A mixed thin film 11 of TiO ₂ and SiO ₂ was formed by dropping an O ₂ -containing alcohol solution, allowing it to dry naturally, and then firing it.

Then, the panel glass 10 on which the mixed thin film 11 of TiO ₂ and SiO ₂ is formed is preheated, and a mixed vapor (Sb / Sn) of dimethyl tin dichloride and antimony trichloride is sprayed on the outer surface thereof. The SnO ₂ thin film 12 doped with Sb was formed by the atmospheric pressure CVD method.

Next, while rotating the panel glass 10 in a preheated state, a SiO ₂ -containing alcohol solution was dropped on the panel glass 10 and then naturally dried and fired to form a SiO ₂ thin film 13.

(Comparative Example) A panel glass as shown in FIG. 1 was prepared, this panel glass was preheated, and a mixed vapor (Sb / Sn) of dimethyl tin dichloride and antimony trichloride was blown on the outer surface thereof. And by the atmospheric pressure CVD method,
A SnO ₂ thin film having a film thickness of 300 Å and doped with Sb was formed.

Then, while preheating this panel glass, while rotating it, a SiO ₂ -containing alcohol solution was dripped onto the panel glass, and then naturally dried and baked to form a SiO ₂ thin film having a film thickness of 1150 Å. Was formed.

The reflectance of each of the thus-produced cathode ray tube panels at a wavelength of 400 to 700 nm was measured,
The results are shown in Fig. 2.

As is apparent from the graph of FIG. 2, the panel of the example had a generally low reflectance over a wide band as compared with the panel of the comparative example.

Further, when the sheet resistance of each cathode ray tube panel was measured, the panel of the example had a low sheet resistance of 1 × 10 ³ Ω / □ and had an excellent electromagnetic wave shielding property. On the other hand, the panel of the comparative example has a surface resistance of 1 × 10 ⁶ Ω / □
And was inferior in electromagnetic wave shielding.

The above-mentioned film thickness (Å) is obtained by a conditional expression of λ / 4n, where λ representing the wavelength of light in the visible region is set to 525 nm and the refractive index of each layer is n. is there.

[0029]

As described above, according to the present invention, it has excellent electromagnetic wave shielding property and antireflection property, and in particular, has a low reflectance over a wide band. It is possible to obtain a panel for a cathode ray tube which does not give a feeling of fatigue.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a cathode ray tube panel of the present invention.

FIG. 2 is a graph showing the reflectances of cathode ray tube panels of Examples and Comparative Examples.

[Explanation of symbols]

10 panel glass 11 mixed thin film of TiO ₂ and SiO ₂ 12 SnO ₂ thin film 13 SiO ₂ thin film

Claims (4)

[Claims] 1. A thin film made of a material having a refractive index between the glass refractive index of the first layer of the outer surface and SnO ₂ having a refractive index is formed, SnO ₂ thin film is formed on the second layer Is
A cathode ray tube panel, wherein a thin film made of a material having a refractive index lower than that of the first layer is formed on the third layer. 2. The cathode ray tube panel according to claim 1, wherein the first thin film is made of a mixture of TiO ₂ and SiO ₂ . 3. The cathode ray tube panel according to claim 1, wherein the third thin film is made of SiO ₂ . 4. The cathode ray tube panel according to claim 1, wherein the second thin film is formed by a CVD method and has a film thickness of 500 Å or more and a sheet resistance of 3 × 10 ³ Ω or less.