JP3292338B2 - Panel for cathode ray tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art A cathode ray tube comprises a panel on which an image is projected, and a funnel and a neck forming the panel 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 mounted around a funnel. Other electronic devices around the tube may malfunction or have an adverse effect on the human body. Therefore, in a 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 provide a performance of shielding electromagnetic waves.

However, in the conventional cathode ray tube panel, the surface resistance (resistance value per square) of the conductive film formed on the outer surface thereof is 1 × 10 ⁶ Ω /.
□ Higher than that, the conductivity is low, and it is insufficient to completely block unnecessary 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. When the thickness is large, there is a problem that the surface reflection is large and an 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 anti-reflection film thereon.
After forming a transparent conductive film made of SnO _{2 with} a thickness of ₂₀₀ to 400 ° on the outer surface of the panel by a CVD method, a cathode ray tube formed by further forming an antireflection film made of SiO ₂ thereon by a spin coating method is formed. Proposed.

[0006]

The above-mentioned cathode ray tube has a relatively good antistatic property because the transparent conductive film made of SnO ₂ is formed on the panel surface. Since the transparent conductive film is as thin as 400 °, the sheet resistance of the transparent conductive film is as high as 1 × 10 ⁶ Ω / □, which is still insufficient to shield unnecessary electromagnetic waves.

Further, this cathode ray tube has a considerably low reflectance in a narrow wavelength region around 550 nm, but has a high reflectance in other visible regions, particularly 400 n.
In the low-wavelength region around m, the reflectivity becomes higher than that of the panel having no film formed on the outer surface, and it is still insufficient to solve the above-mentioned problem that the image becomes difficult to see. is there. In addition, such a panel having a low reflectance only in a narrow wavelength range has a drawback that a person who views an image feels a deep color, and thus easily gives a feeling of fatigue.

Accordingly, an object of the present invention is to provide an excellent electromagnetic wave shielding property and a low reflectance over a wide wavelength range (hereinafter, referred to as a broadband), thereby giving a viewer a feeling of fatigue. There is no need to provide a panel for a cathode ray tube.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems and objects. An SiO ₂ film is formed on a first layer on the outer surface side, and a glass refraction is formed on a second layer. Rate and S
A thin film made of a material having a refractive index between nO _{2 and} the refractive index of nO ₂ is formed, a SnO ₂ thin film is formed on the third layer, and a material having a lower refractive index than the second layer is formed on the fourth layer. A panel for a cathode ray tube, wherein a thin film is formed.

A second thin film is made of TiO ₂ and SiO
It is characterized by consisting of a mixture of ₂ .

The fourth thin film is made of SiO ₂ .

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

[0013]

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

Further, in the present invention, a SiO ₂ thin film is formed as the first thin film, and the refractive index of glass and the refractive index of the third SnO ₂ thin film are formed as the _second thin film. Since a thin film having a refractive index between them is formed and a thin film having a lower refractive index than the second layer is formed as the fourth thin film, it is possible to obtain a low reflectance over a wide band. Become.

The material of the second 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 .
₂ , Ta ₂ O ₅ , ZnS, a mixture of CeO ₂ and SiO ₂ , etc. can be used. As the material of the fourth thin film, SiO ₂ , MgF _2, etc. can be used. Considering the prevention performance and cost, T
a thin film of a mixture of iO ₂ and SiO ₂ (refractive index = 1.7),
Most preferably, a thin film of SiO ₂ (refractive index = 1.46) is used as the fourth layer.
Any of spin coating, dip coating, and spray coating is suitable.

The CVD method for forming SnO ₂ is cheaper than other coating methods and is suitable for mass production. Usually, when a thin film of SnO ₂ is formed directly on the surface of a panel by the CVD method, an alkali component in the glass comes out to the surface of the panel due to the heat treatment of the panel, so that 3 × 10 ³ Ω / □
In order to obtain the following resistance values, the film thickness must be made considerably thick. However, the SiO ₂ thin film is formed first layer, a thin film having a refractive index between the refractive index and SnO ₂ of the refractive index of the glass in the second layer is formed, forming a thin film of SnO ₂ is formed thereon By doing so, it is possible to prevent the alkali component from coming out on the surface of the panel, and it is possible to stably obtain a resistance value of 3 × 10 ³ Ω / □ or less even when the SnO ₂ film is thin. is there. Further, a small amount of Sb is added to SnO ₂ constituting the third thin film in order to reduce the resistance value.
It is possible to add ₂ O ₃ .

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a cathode ray tube panel of the present invention will be described in detail based on embodiments.

FIG. 1 is a longitudinal sectional view of a cathode ray tube panel according to the present invention.

This panel glass 10 (refractive index 1.53
On the outer surface of 6), a SiO ₂ thin film 11 (refractive index: 1.46) having a thickness of 942 ° is formed as a first layer,
TiO ₂ and Si having a thickness of 809 ° as a second layer
A mixed thin film 12 of O ₂ (refractive index 1.7) is formed,
SnO ₂ thin film 13 having a thickness of 688 ° as a layer
(Refractive index: 2.0), and 9 as a fourth layer.
SiO ₂ thin film 14 having a thickness of 42 ° (refractive index 1.4)
6) is formed.

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

First, an alcohol solution containing SiO ₂ is dropped on the panel glass while washing and drying and rotating the glass in a preheated state, and then naturally dried and fired to form an SiO ₂ thin film 11. did.

After that, while rotating the panel glass 10 on which the SiO ₂ thin film 11 is formed in a preheated state, an alcohol solution containing TiO ₂ and SiO ₂ is dropped thereon, and the mixture is naturally dried and fired. T
A mixed thin film 12 of iO ₂ and SiO ₂ was formed.

Further, the panel glass 10 is preheated, and a mixed vapor (Sb / Sn) of dimethyltin dichloride and antimony trichloride is sprayed on the outer surface of the panel glass 10 to perform normal pressure CVD.
The SnO ₂ thin film 13 doped with Sb was formed by the method.

Next, while rotating the panel glass 10 in a preheated state, the same SiO 2 as the first layer is formed thereon.
After dripping the _2- containing alcohol solution, it was naturally dried and baked to form the SiO ₂ thin film 14.

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

Next, while rotating the panel glass in a preheated state, an alcohol solution containing SiO ₂ is dropped on the panel glass, and the solution is naturally dried and baked, whereby an SiO ₂ thin film having a thickness of 1150 ° is obtained. Was formed.

The reflectance of each of the cathode ray tube panels thus manufactured at a wavelength of 400 to 700 nm was measured.
The result is shown in FIG.

As is clear from the graph of FIG. 2, the panel of the example had an overall lower reflectance over a wide band than the panel of the comparative example.

When the sheet resistance of each cathode ray tube panel was measured, the panels of the examples had a low sheet resistance of 1 × 10 ³ Ω / □ and had excellent electromagnetic wave shielding properties. On the other hand, the panel of the comparative example has a sheet resistance of 1 × 10 ⁶ Ω / □.
And it was inferior in electromagnetic wave shielding.

The above 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 the film of each layer is n. is there.

[0031]

As described above, according to the present invention, since it has excellent electromagnetic wave shielding and anti-reflection properties and has a low reflectance over a wide band, it can be seen by the eyes of the viewer. It is possible to obtain a cathode ray tube panel that does not give a feeling of fatigue.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a panel for a cathode ray tube of the present invention.

FIG. 2 is a graph showing the reflectance of the cathode ray tube panels of the example and the comparative example.

[Explanation of symbols]

10 panel glass 11 SiO ₂ thin film 12 mixed thin film of TiO ₂ and SiO ₂ 13 SnO ₂ thin film 14 SiO ₂ thin film

Continuation of the front page (56) References JP-A-2-72549 (JP, A) JP-A-63-261646 (JP, A) JP-A-5-113505 (JP, A) JP-A-58-26408 (JP) , A) JP-A-7-37533 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01J 29/88 H01J 29/89

Claims (4)

(57) [Claims] 1. An SiO ₂ film is formed as a first layer on the outer surface side, and a thin film made of a material having a refractive index between that of glass and that of SnO ₂ is formed as a second layer. A panel for a cathode ray tube, wherein a SnO ₂ thin film is formed on a third layer, and a thin film made of a material having a lower refractive index than the second layer is formed on a fourth layer. _2. The panel for a cathode ray tube according to claim 1, wherein the _second thin film is made of a mixture of TiO ₂ and SiO ₂ . 3. The panel for a cathode ray tube according to claim 1, wherein the fourth thin film is made of SiO ₂ . 4. The cathode ray tube panel according to claim 1, wherein the third thin film is formed by a CVD method and has a thickness of 500 ° or more and a sheet resistance of 3 × 10 ³ Ω or less.