JPH07312186A - Reflection antistatic cathode-ray tube and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide a cathode-ray tube having a wide reflection antistatic film in a low reflection factor wavelength region by providing the reflection antistatic film, comprising the first to third layers displaying a prescribed relation in a wavelength of the highest visual sensitivity, refraction index of the layer and a film thickness, in a face external surface. CONSTITUTION:A reflection antistatic film 11, comprising three layer films of the first to third layers 12a to 12c, is provided on an external surface in a face 1 of a color cathode-ray tube. When assume lambda0 for wavelength (lambda0=550nm) of incident light of the highest visual sensitivity, n1 to n3 for respectively refraction factor of the first to third layers and d1 to d3 for respectively film thickness, the first to third layers are formed in the refraction factor and the film thickness respectively satisfying a relation n1=1.65 to 1.75, 0.9Xlambda0/4<=n1d1<=1.1Xlambda0/4 in the first layer, satisfying a relation n2=1.90 to 2.00, 0.9Xlambda0/2<=n2d2<=1.1Xlambda0/2 in the second layer and satisfying a relation n3=1.40 to 1.45, 0.9Xlambda0/4<=n3d3<=1.1Xlambda0/4 in the third layer. The first layer 12a is composed of a mixture of SnO2, SiO2 the second layer 12b is composed of TiO2 by a liquid phase method, and the third layer 12c is composed of a mixture of MgF2, SiO2 by the liquid phase method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflection-prevention type cathode ray tube having a reflection-prevention film on the outer surface of the face of a cathode ray tube and a method for producing the same.

[0002]

2. Description of the Related Art Generally, a cathode ray tube is constructed as shown in FIG.
Phosphor screen 2 on the inner surface of face 1 made of glass
Is formed, and the phosphor screen 2 is horizontally and vertically scanned by an electron beam emitted from an electron gun 5 arranged in the neck 4 of the funnel 3 to form an image display structure. In the color cathode ray tube, a shadow mask 6 is arranged inside the phosphor screen 2 so as to face the phosphor screen 2. Reference numeral 7 is an explosion-proof band for tightening the side wall of the face 1.

In such a cathode ray tube, in which a high voltage is applied to the phosphor screen 2 in order to display a particularly high-luminance image, the high voltage is induced on the outer surface of the face 1 and charged. If dust or the like adheres to the outer surface of the face 1 due to this charging, the image becomes difficult to see.
When a human body comes into contact with the outer surface of the face 1, an electric shock is received. Further, since the outer surface of the face 1 of the cathode ray tube is generally formed as a mirror surface, external light is reflected on the outer surface of the face 1 and the contrast of an image viewed through the face 1 is deteriorated. Especially in computer displays and the like, since the screen is often viewed from a short distance, this reflection of external light promotes eye fatigue.

In order to prevent such charging of the outer surface of the face or reflection of external light, it has been conventionally known to form a reflective antistatic film having a reflection and antistatic effect on the outer surface of the face.

As a method for uniformly and inexpensively forming this antireflection film, a dispersion liquid in which fine particles of a conductive metal oxide are dispersed in an alcohol solution of silicon alkoxide is applied to the outer surface of the face by a spray method and then baked. There is a method of forming a concavo-convex film with a conductive metal oxide fine particle to impart conductivity, and reducing the reflectance by diffusing and reflecting external light due to the fine concavities and convexities on the surface. However, since the antistatic film formed by this method has an uneven surface, the image seen through the antistatic film is blurred and the resolution is degraded. Further, there are problems that the screen becomes whitish due to the fine irregularities on the surface and the contrast deteriorates.

As another forming method, an optical multi-layer film is formed on the glass plate by a vapor phase method such as vacuum deposition or sputtering, and the glass plate is adhered to the outer surface of the face and reflected by the interference effect of light. There are ways to prevent this. However, since this method forms an optical multilayer film by a vapor phase method, a large-scale apparatus is required, and there is a problem that the manufacturing cost becomes high. Therefore, there is a problem that it can be used only in some high-end models.

As a method for solving the above-mentioned problems, recently, a method of forming an antireflection film composed of a multilayer film on the outer surface of the face by a liquid phase method has been developed. According to this method, it is possible to form an antireflection film at a low cost without deterioration of resolution and contrast. However, this liquid phase method
Since it is difficult to control the film thickness, it is desirable to set the film thickness to about 2 to 3 layers, and the film thickness of 4 layers or more is very difficult in manufacturing.

[0008]

As described above, as a method for forming an antireflection film for a cathode ray tube, a method for forming an antireflection film composed of a multilayer film by a liquid phase method has been developed.
However, it is very difficult to form a multilayer film by the liquid phase method in order to control the film thickness, and it is very difficult to form a four-layer film or more.
It is desirable to have a layer thickness.

When forming an antireflection film consisting of two or three layers by this liquid phase method, what is important is the refractive index and film thickness of each film. In the antireflection film composed of a two-layer film, the refractive index of air is n0 (n0 = 1.00), the refractive index of the face made of glass is ns (ns = 1.52), and the first layer is formed on the outer surface side of the face. The refractive index is n1, the refractive index of the second layer on the first layer is n2, the film thickness of the first layer is d1, the film thickness of the second layer is d2, and the wavelength of incident light with the highest visibility is λ0. (Λ0 = 5
50 nm), n1 / n2 = (ns / n0) ¹ / 2n1d1 = n2d2 = .lambda.0 / 4 may be calculated from the calculation of the spectral reflectance.

In this case, it is desired to lower the refractive index n2 of the second layer as much as possible. Therefore, the refractive index n2 of the second layer obtained by liquid phase method, by utilizing the refractive index n2 = 1.40 of a mixture of Mg F ₂ and Si O ₂ to the lowest refractive index is obtained, the above equation When n1, d1 and d2 to be satisfied are obtained, n1 = 1.73 d1 = 79 nm d2 = 98 nm. However, when a two-layer film is formed with these refractive indexes and film thicknesses, the incident light in the vicinity of λ0 has low reflection, but the incident light in the vicinity of both ends of the visible light wavelength has a high reflectance and the reflection is high. It is not preferable because the coloring of the prevention film becomes large.

On the other hand, the antireflection film composed of the three-layer film can widen the low reflectance wavelength region as compared with the two-layer film. In this case, the refractive index n of the outermost third layer of the three-layer film is n.
3 has the lowest refractive index n3 = 1.40 obtained by the liquid phase method like the above two-layer film, and the low reflectance wavelength range is widened, the first, second, It is necessary for the three layers to have a refractive index and a film thickness that satisfy one of the conditions in Tables 1 and 2 below.

[0012]

[Table 1]

[Table 2] However, when actually trying to form a three-layer film with such a refractive index and film thickness, there are the following problems. That is, the refractive index of TiO ₂ used as a high refractive index substance is about 2.50 in the case of a crystalline substance, but when an antireflection film is formed on the outer surface of the face of a cathode ray tube by the liquid phase method. However, since the subsequent firing temperature is about 200 ° C., at this temperature, TiO ₂ is not completely crystallized and the refractive index of TiO ₂ does not reach 2.00 or more. It has been confirmed by experiments by the researchers. Further, in the antireflection film formed of the three-layer film formed by the liquid phase method, the reflectance near both ends of the visible light wavelength region is high, and the antireflection film is highly colored. That is, it is difficult to form the three-layer film shown in Tables 1 and 2 by the liquid phase method, and it is impossible to form an antireflection film having a wide low reflectance wavelength range which is inherent in the three-layer film. There is.

The present invention has been made in order to solve the above-mentioned problems, and is made of a three-layer film having a wide reflection range of a low reflectance wavelength region using a substance having a refractive index of 2.00 or less. An object of the present invention is to obtain a cathode ray tube having a reflection antistatic film and a method for manufacturing the same.

[0014]

In a reflective antistatic cathode ray tube having a reflective antistatic film on the outer surface of the face, the reflective antistatic film is a three-layer film, and the wavelength of incident light with the highest luminosity is λ 0 ( λ0 = 550 nm), the refractive index of the first layer on the outer surface of the face is n1, the film thickness is d1, the refractive index of the second layer on the first layer is n2, the film thickness is d2, and the second layer on the second layer is When the refractive index of three layers is n3 and the film thickness is d3, the first layer is n1 = 1.65 to 1.75 0.9 × λ0 / 4 ≦ n1 d1 ≦ 1.1 × λ0 / 4 Second layer N2 = 1.90 to 2.00 0.9 × λ0 / 2 ≦ n2 d2 ≦ 1.1 × λ0 / 2 The third layer has n3 = 1.40 to 1.45 0.9 × λ0 / 4 ≦ n3 The film was formed with a refractive index and a film thickness satisfying d3 ≤ 1.1 x λ0 / 4.

The first layer is formed of SnO ₂ , TiO ₂ ,
Mixture of Si O _2, the second layer Ti O _2, the third layer Mg F
₂ , a mixture of SiO ₂ .

Further, in a method of manufacturing a reflection-prevention type cathode ray tube, wherein a reflection-prevention film is formed on the outer surface of the face,
Sn O _2, Ti O ₂ by a liquid phase method on the face outer surface,
Forming a first layer consisting of a mixture of SiO _2, this by a liquid phase method on the first layer to form a second layer of Ti O _2, Mg F ₂ by a liquid phase method in the second layer on, Si A third layer was formed consisting of a mixture of O ₂ .

[0017]

When the antireflection film composed of the three-layer film is formed as described above, even if a material whose refractive index becomes 2.00 or less by low temperature baking at 200 ° C. after being formed by the liquid phase method, On the outer surface of the face of the cathode ray tube, it is possible to form a reflection antistatic film having a wide low reflection wavelength range, little coloring of the antireflection film and having an antistatic effect.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described based on embodiments with reference to the drawings.

FIG. 1 shows a reflection-prevention type cathode ray tube which is one of the embodiments. This cathode ray tube is a color cathode ray tube, and has a face 1 (panel) made of glass having a skirt portion 10 formed in the peripheral portion and an envelope having a funnel 3 joined to the skirt portion 10 of the face 1. Then
A phosphor screen 2 made of a phosphor layer of three colors is formed on the inner surface of the face 1, and a shadow mask 6 is arranged inside the face 1 so as to face the phosphor screen 2. On the other hand, the electron gun 5 is arranged in the neck 4 of the funnel 3. Further, an explosion-proof band 7 is attached to the outer periphery of the skirt portion 10 of the face 1. Further, a reflection antistatic film 11 is provided on the outer surface of the face 1. The reflective antistatic film 11 has its peripheral portion connected to the explosion-proof band 7 for grounding.

As shown in FIG. 2, the antireflection film 11 is a three-layer film including first, second, and third layers 12a, 12b, and 12c, which are sequentially formed on the outer surface of the face 1. . The first layer 12a on the face 1 side is Sn O ₂ ,
It consists of a mixture of Ti O _2, Si O _2, the refractive index n1 and thickness d1 is formed on each of n1 = 1.70 d1 = λ0 / 4n1 = 81nm. The conductive property of the antireflection film 11 is given by SnO ₂ in the first layer 12a.

The second layer 12b on the first layer 12a is made of T
consists i O _2, a refractive index n2 and thickness d2 is formed on each of n2 = 1.92 d1 = λ0 / 2n2 = 143nm.

The third layer 12c on the second layer 12b is M
g F _2, consist of a mixture of Si O _2, the refractive index n3 and a thickness d3 is formed on each of n3 = 1.42 d3 = λ0 / 4n3 = 97nm.

Antireflection film 11 consisting of this three-layer film
Are formed by the liquid phase method. First, a dispersion of SnO ₂ particles dispersed in an alcohol solution of a titanium compound and a silane compound which are soluble in alcohol is applied on the outer surface of the face by spin coating and dried, and then this coating film is heated at a temperature of 200 ° C. The first layer is formed by firing.
Next, an alcohol solution of an alcohol-soluble titanium compound such as titanium alkoxide or titanium tetrachloride is applied onto the above-mentioned first layer by spin coating and dried to form a second layer.
Deposit layers. Then, a dispersion liquid in which fine particles of MgF ₂ are dispersed in an alcohol solution of silicon alkoxide is applied onto the second layer by spin coating and dried, and then this coating film is baked together with the second layer at a temperature of 200 ° C. Form a third layer.

By the way, as described above, when the reflective antistatic film 11 consisting of a three-layer film is formed on the outer surface of the face,
The first layer, the second layer, and the third layer each have a refractive index n of 2.
Even if it is formed using a substance of 00 or less, it has a sufficiently low reflectance in the vicinity of the wavelength (λ 0 = 550 nm) with the highest luminosity, has a wide low reflection wavelength range, and has little coloring of the antireflection film. It can be a reflection antistatic film having an antistatic effect.

That is, in FIG. 2, the above-described first layer has a refractive index n1 of 1.73 and a film thickness d1 of 79 nm, and a second layer having a refractive index n2 of 1.40 and a film thickness d2 of 98 nm. The reflectance of the two-layer film is shown by curve 14, the reflectance of the three-layer film shown in Table 1 is shown by curve 15a, and the reflectance of the three-layer film shown in Table 2 is shown by curve 1
As shown in 5b, both the two-layer film and the three-layer film have sufficiently low reflectance near the wavelength where the visibility is highest, but have high reflectance near both ends of the visible light wavelength range. Therefore, the low reflection wavelength region is relatively narrow, and the reflectance is high near both ends of the visible light wavelength region, so that the coloring of the antireflection film becomes large. However, the above-mentioned refractive index n1 is 1.7.
0, the first layer having a film thickness d1 of 81 nm, and the refractive index n2 of 1.9.
2. The second layer having a film thickness d2 of 143 nm and the refractive index n3 of 1.
42, the reflectance of the anti-reflective coating 11 of this example composed of the third layer having a film thickness d3 of 97 nm is as shown by the curve 16.
Not only the reflectance is sufficiently low near the wavelength where the visibility is highest, but also the reflectance does not become too high near both ends of the visible light wavelength range, and it has a wide low reflection wavelength range and an antireflection film. It is a good one with little coloring.

In the above embodiment, the first layer on the face side of the antireflection film has a refractive index n1 of 1.70 and a film thickness d1.
Is 81 nm, and the refractive index n2 of the second layer on the first layer is 1.9.
2. The film thickness d2 was 143 nm, the refractive index n3 of the third layer on the second layer was 1.42, and the film thickness d3 was 97 nm.
The anti-reflection film formed of a layer film can be changed by changing the composition of the dispersion liquid for forming each layer and the coating conditions, whereby the refractive index n1 and the film thickness d of the first layer are changed.
1 is set to n1 = 1.65 to 1.75 0.9 × λ0 / 4 ≦ n1 d1 ≦ 1.1 × λ0 / 4, the refractive index n2 and the film thickness d2 of the second layer are set to n2 = 1.90. .About.2.00 0.9.times..lambda.0 /2.ltoreq.n2 d2 .ltoreq.1.1.times..lamda.0 / 2, the refractive index n3 and the film thickness d3 of the third layer are: n3 = 1.40 to 1.45 0.9.times. Even in the range of .lambda.0 / 4.ltoreq.n3 d3.ltoreq.1.1.times..lambda.0 / 4, a reflection antistatic film having the same effect can be obtained.

Although the color cathode ray tube has been described in the above embodiment, the present invention can be applied to cathode ray tubes other than the color cathode ray tube.

[0028]

The antireflection film on the outer surface of the face is a three-layer film having a refractive index n1 and a film thickness d1 on the outer surface of the face.
, N1 = 1.65 to 1.75 0.9 × λ0 / 4 ≦ n1 d1 ≦ 1.1 × λ0 / 4 is formed, and the refractive index n2 is formed on this first layer.
, And a film thickness d2 of n2 = 1.90 to 2.00 0.9 × λ0 / 2 ≦ n2 d2 ≦ 1.1 × λ0 / 2 is formed, and refraction is performed on this second layer. Rate n3
, A film thickness d3 forms a third layer satisfying n3 = 1.40 to 1.45 0.9 × λ0 / 4 ≦ n3 d3 ≦ 1.1 × λ0 / 4, and the first layer is Sn.
O _2, a mixture of Ti O _2, Si O _2, the second layer Ti
When O ₂ and the third layer are made of a mixture of MgF ₂ and SiO ₂ , the film has a refractive index of 2.0 after baking at a low temperature of 200 ° C.
Even if a substance of 0 or less is used, it has a sufficiently low reflectance in the vicinity of the wavelength with the highest luminosity by the liquid phase method, has a wide low reflection wavelength range, has little coloring of reflection, and has an antistatic effect. A reflective antistatic film can be formed.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a reflection-prevention type cathode ray tube according to an embodiment of the present invention.

FIG. 2 is a diagram showing the structure of the antireflection film.

FIG. 3 is a diagram showing the reflection characteristics of the antireflection film in comparison with the two-layer film and the antireflection films shown in Tables 1 and 2.

FIG. 4 is a diagram showing a configuration of a color cathode ray tube.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Face 2 ... Phosphor screen 7 ... Explosion-proof band 11 ... Reflective antistatic film 12a ... 1st layer 12b ... 2nd layer 12c ... 3rd layer

Claims (3)

[Claims] 1. A reflective antistatic cathode ray tube having a reflective antistatic film on the outer surface of the face, wherein the antireflective film is a three-layer film sequentially laminated on the outer surface of the face, and has the highest visibility. The wavelength of high incident light is λ0 (λ0 = 550 nm), the refractive index of the first layer on the outer surface of the face is n1, the film thickness is d1, the refractive index of the second layer on this first layer is n2, and the film is When the thickness is d2, the refractive index of the third layer on the second layer is n3, and the film thickness is d3,
The layer is n1 = 1.65 to 1.75 0.9 × λ0 / 4 ≦ n1 d1 ≦ 1.1 × λ0 / 4 The second layer is n2 = 1.90 to 2.00 0.9 × λ0 / 2 ≦ n2 d2 ≦ 1.1 × λ0 / 2 The third layer has a refractive index and a film thickness satisfying n3 = 1.40 to 1.45 0.9 × λ0 / 4 ≦ n3 d3 ≦ 1.1 × λ0 / 4 A reflective antistatic cathode ray tube characterized in that it is formed. 2. The first layer comprises SnO ₂ , TiO ₂ and SiO ₂
Mixture, the second layer is Ti O _2, third layer Mg F _2, Si of
The anti-reflection type cathode ray tube according to claim 1, which is composed of a mixture of O ₂ . 3. A method for manufacturing a reflection-preventing type cathode ray tube in which a reflection-preventing film is formed on the outer surface of the face, wherein Sn O ₂ , Ti ₂ O _{3 is} formed on the outer surface of the face by a liquid phase method.
_2, Si O to form a first layer consisting of a mixture of _2, this by a liquid phase method on the first layer to form a second layer of Ti O _2, Mg F by a liquid phase method in the second layer on the _A method for producing a reflection-prevention type cathode ray tube, which comprises forming a third layer made of a mixture of SiO ₂ and SiO ₂ .