JPH052988A - Reflex preventive film forming method for display device - Google Patents

Abstract

PURPOSE:To produce a reflex preventive film having a low reflex rate without impairing the resolution of the surface image by forming the reflex preventive film on the outer surface of a glass base from a multi-layer optical film consisting of two or more layers having different refraction coefficient, and providing the outermost layer with specific convex/concave pitch, surface roughness, and pore diameter. CONSTITUTION:Over the outer surface of a panel 10 constituting a color image receiving tube, a reflex preventive film 16 is provided in a laminate structure consisting of an upper and a lower layer 17, 18. The lower layer 17 is formed so as to meet the thickness condition d=lambda/4n(lambda=550nm) and be prepared from particulates of a high refraction coefficient oxide such as TiO2, SiO2, ZnO2 having a mean particle size of 50nm which are subjected to binding with SiO2, while the upper layer 18 has a convex/concave pitch of 10-1000nm, a surface roughness of 10-50nm, and the mean dia. of pores discrete uniformly being no more than 50nm. It further specifies so that the refraction coefficient (n) of the upper layer 18 is as small as 1.32 approximately, compared with the refraction coefficient (n) of a SiO2 flat/smooth film free of pores which measures 1.46. To form the upper layer 18, a coating liquid is used by mixing 30vol.% or more water soluble alcohol having a boiling point no less than 90 deg.C with an alcoholic solution of ethyl silicate, which is followed by removal of the alcoholic components.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming an antireflection film for a display device, and more particularly to a method for forming an antireflection film on the outer surface of a glass substrate of a display surface such as a cathode ray tube having a phosphor screen. The present invention relates to an effective antireflection film forming method.

[0002]

2. Description of the Related Art Generally, in a cathode ray tube, a phosphor screen is formed on the inner surface of a face plate (glass substrate) made of glass with a smooth outer surface, and an electron beam emitted from an electron gun is generated by a magnetic field generated by a deflection yoke. By deflecting and scanning the phosphor screen horizontally and vertically,
An image is displayed on the phosphor screen, and the image is viewed from the outside through the face plate. Therefore, if the outer surface of the face plate is smooth, the reflection of external light on the outer surface overlaps the image, and the quality of the image viewed from the outside through the face plate is significantly deteriorated.

Therefore, conventionally, there is a cathode ray tube in which an antireflection film is formed on the outer surface of the face plate in order to prevent the deterioration of the image.

As the method for forming the antireflection film, (a) a sand blast method in which an abrasive is sprayed on the outer surface of the glass substrate to make it uneven, or a method of forming unevenness by corroding it with hydrofluoric acid (b) beforehand Ethyl silicate (Si (OR) ₄ ) (R: was added to the outer surface of the glass substrate preheated to 50 to 60 ° C.
(Alkyl group) Alcohol solution is sprayed to form a film, and then the alcohol component is evaporated to form a concavo-convex film, and the concavo-convex film is fired. (C) On the outer surface of the glass substrate, such as SiO ₂ or Mg F ₂ A method of forming a concavo-convex film by baking after applying a dispersion liquid in which fine particles are dispersed in an alcoholic solution of ethyl silicate (d) A method of forming a multilayer vapor deposition film by vapor deposition (e) Oxide fine particles on the outer surface of a glass substrate There is a method of forming a multilayer film by a sol-gel method using a dispersion liquid in which is dispersed in an alcohol solution of ethyl silicate or a metal alkoxide solution.

Among these methods, the method (a) for forming irregularities by sandblasting or corrosion is a method for directly forming irregularities on the outer surface of the face plate.
There are problems that the cathode ray tube bulb cannot be regenerated and that dirt easily adheres.

On the other hand, in the method (b) of spraying the alcohol solution of ethyl silicate, the bulb can be regenerated and the antireflection film can be formed relatively easily.

However, both of the methods (a) and (b) are intended to prevent reflection by forming unevenness on the outer surface of the glass substrate or by forming an uneven film on the outer surface and diffusing outside light by the unevenness. However, since the unevenness simultaneously diffuses the display image, there is a problem that the resolution is deteriorated.

A method of applying a dispersion prepared by dispersing fine particles such as SiO ₂ and Mg F _{2 in} an alcohol solution of ethyl silicate in (C) is disclosed in JP-A-64-76001.
JP-A-1-154444 and JP-A-1-154444
5 and Japanese Patent Application Laid-Open No. 2-175601, the antireflection film described in Japanese Patent Application Laid-Open No. 1-154444 will be described as an example. As shown in FIG. The antireflection film is formed by applying a dispersion liquid in which fine particles of SiO ₂ having a diameter of 10 to 1000 nm are dispersed in an alcohol solution of ethyl silicate to the outer surface of the glass substrate by a spin coating method, and then firing.

Therefore, this antireflection film is formed of SiO ₂
It consists of the fine particles 1 and the SiO ₂ thin film 2 that binds the fine particles 1. Since the refractive index of the glass substrate 3 is 1.52, which is rather low as 1.47, the reflectance may be slightly different due to the interference effect. Although reduced, antireflection effect of the antireflection film itself well as a little anti-reflection effect of the anti-reflection film, air by the uneven structure of the coated surface by Si O ₂ particles 1 - continuous volume ratio between thin The change achieves low reflection characteristics.

However, this antireflection film has a large effect of diffusing light by the SiO ₂ fine particles 1 and a slight effect of diffusing it due to unevenness, thus degrading the resolution.
To reduce the degradation of the resolution, although small diameter of the Si O ₂ particles 1 and Si O ₂ smoothing thin film 2 is effective, smaller diameter of the thus Si O ₂ particles 1, SiO ₂ When the thin film 2 is smoothed, the reflection characteristics are deteriorated.

In order to realize a low reflectance, S
It is necessary to increase the content of the iO ₂ fine particles 1 to increase the degree of unevenness, but in this case, the antireflection film is likely to have a fine pore structure, and the SiO ₂ fine particles and the SiO ₂ thin film are likely to be formed. The binding force is weakened and wear resistance is significantly deteriorated.

That is, the antireflection film which uses the SiO ₂ fine particles to prevent reflection by the interference effect as described above has a problem in terms of resolution and abrasion resistance.

As an example of the multilayer vapor deposition film formed by the vapor deposition of (d), FIG. 7 shows Mg F ₂ having a refractive index n 1 = 1.38.
And AR ₂ + Pr ₆ O ₁₁ having a refractive index of n 2 = 2.06 are alternately deposited to form four layers of deposited films 5 a, 5 b, 6 a and 6 b AR
The (Anti Refrection) panel is shown. The film thickness d of the multilayer vapor deposition film of this AR panel is 930 Å for the first layer 5a, 1270 Å for the second layer 6a, and 3rd layer 5b.
Is 290 Å and the fourth layer 6b is 140 Å.

By using such a multilayer vapor deposition film, the specular reflectance can be made 0.1 or less due to the interference effect. However, if this multilayer vapor deposition film is applied to a large-sized cathode ray tube having a large screen, a large-scale manufacturing facility is required, and there is a problem that the manufacturing cost becomes high.

In the sol-gel method (e), the desired oxide fine particles are treated with an ethyl silicate alcohol solution or Ti.
, Sn, or another metal alkoxide solution is applied to the outer surface of the glass substrate by a method such as spraying, spinning, dipping, or rolling, and is baked.

The multi-layer film formed by this method has the same effect as that of the above-mentioned multi-layer vapor-deposited film, but the film structure includes oxide fine particles having a high or low refractive index and Si having a refractive index n = 1.46. Since it is in a mixed state with O ₂ fine particles, the refractive index of the film itself is higher in the case of the low refractive index oxide fine particles than that of the high refractive index or low refractive index oxide fine particles, and the high refractive index oxide In the case of fine particles, it becomes low, and its refractive index changes depending on the content of oxide fine particles.

In general, a multilayer film having a low reflection property has a low refractive index so that n × d = λ / 4 is satisfied, where n is a refractive index, d is a film thickness, and λ is a central wavelength (550 nm) in the visible region. It is formed by combining a refractive index film and a high refractive index film.

For example, in the case of a multi-layer film having a two-layer structure, the first layer of the upper layer is a dispersion liquid in which Mg F ₂ fine particles (n = 1.38) having the lowest refractive index are dispersed in an alcohol solution of ethyl silicate. Since the upper limit of the refractive index of the upper layer is 1.40, the lower limit of the refractive index of the film in this case is 1.40. The refractive index of the two layers must be 1.73. When the multilayer film is formed by the sol-gel method as described above, the low refractive index film has a refractive index of 1.40 or more, and therefore the high refractive index film must have a refractive index of 1.70 or more.
To obtain the desired refractive index, the content of fine particles must be increased. As a result, the SiO ₂ bond in the film (the bond between the fine particles and the SiO ₂ thin film) is reduced, and the wear resistance is significantly deteriorated. To improve this abrasion resistance, 5
It requires high-temperature firing at 00 ° C. or higher, which is difficult to manufacture. In particular, in the case of metal alkoxide, a desired refraction film can be obtained by baking at a high temperature of 500 ° C. or higher, but the abrasion resistance is still low.

Regarding the sol-gel method, the case of a two-layer film has been described, but as for the reflection characteristics, the reflectance can be lowered and the low reflection band can be widened by making the number of layers more. ..

However, this sol-gel method has problems in reflection characteristics and abrasion resistance as described above, and it is difficult to control the film thickness to be uniform for a large cathode ray tube having a large screen. However, in order to improve them, there is a problem that the cost tends to increase in manufacturing equipment.

[0021]

As described above, the conventional antireflection film forming methods for a display device include (a) a method of directly forming irregularities on a glass substrate by sandblasting or corrosion, and (b) an ethyl silicate method. A method for forming a concavo-convex film using an alcohol solution, (c) a method for forming a concavo-convex film using a dispersion liquid in which fine particles such as SiO ₂ and Mg F ₂ are dispersed in an alcohol solution of ethyl silicate, (d) There are various methods such as a method of forming a multilayer vapor deposition film by vapor deposition and a method of forming a multilayer film by a (e) sol-gel method.
There are problems with the valve reproduction, resolution, reflection characteristics, and wear resistance.

The present invention has been made in view of the above problems of the prior art, and has a relatively low reflectance and a wide bandwidth in a low reflection range, and relatively easily forms an antireflection film that hardly deteriorates the resolution of a display screen. The purpose is to be able to.

[0023]

In an antireflection film forming method for a display device, when forming a multilayer optical film having two or more layers having different refractive indexes on an outer surface of a glass substrate of a display surface, an alcohol solution of ethyl silicate is used. Boiling point 90 relative to solvent
The outermost layer is formed by using a coating solution obtained by mixing 30% by volume of water-soluble alcohol having a temperature of ℃ or more, and the alcohol component is removed by washing the outermost layer with water having a temperature of 60 ° C or less to remove the surface of the outermost layer. Concavo-convex pitch 10-1000 nm, irregularity roughness 1
An uneven surface of 0 to 50 nm was formed, and fine pores having an average diameter of 50 nm or less were included therein.

[0024]

As described above, the surface of the outermost layer has the uneven pitch 10
When the surface has an uneven surface of ˜1000 nm and a roughness roughness of 10 to 50 nm and has fine pores with an average diameter of 50 nm or less, the refractive index of the outermost layer is such that the volume ratio of air to the film due to the fine pores and the air to the maximum due to the fine roughness. Due to the two effects of continuous volume ratio change with the outer layer, the value can be reduced to a value that cannot be realized by an ordinary optical medium, and an antireflection film exhibiting a reflection spectrum with a wide band and low reflectance can be obtained. Since the spectrum is broad, even if the film is formed by a simple film forming method in which the film thickness control is insufficient, the change in the reflectance due to the film thickness variation can be suppressed to a slight extent.

[0025]

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

FIG. 1 shows a color picture tube according to the embodiment. This color picture tube has an envelope composed of a glass panel (glass substrate) 10 and a funnel 11 integrally joined to the panel 10, and the dot-shaped or striped three-color fluorescent light is provided on the inner surface of the panel 10. A phosphor screen 12 composed of a body layer is formed, and a shadow mask 13 is mounted inside the phosphor screen 12 so as to face the phosphor screen 12. An electron gun 15 is arranged inside the neck 14 of the funnel 11. Then, the three electron beams emitted from the electron gun 15 are deflected by a magnetic field generated by a deflection yoke (not shown) mounted on the outside of the funnel 11, and the phosphor screen 12 is horizontally and vertically scanned. The glass panel 10 is formed to have a structure for displaying a color image on the phosphor screen 12, and the glass panel 10 serves as a substrate for the display surface.

In this color picture tube, an antireflection film 16 is formed on the outer surface of the panel 10.
As shown in FIG. 2, the antireflection film 16 includes two upper and lower layers 17,
It consists 18 stacked structure, the mean particle size 50nm less than the high refractive index oxide 19, for example, _{Ti O 2, Si O 2,} Zn O 2, S
A lower layer (second layer) 17 satisfying a film thickness d = λ / 4n (λ = 550 nm) obtained by binding fine particles of n O ₂ , In ₂ O ₃ or the like with SiO ₂ and an uneven pitch P of 100 to 1000 nm ,
Sn O ₂ satisfying an average film thickness d = λ / 4n (λ = 550 nm), which has an uneven surface with a surface roughness h of 10 to 50 nm and has uniformly dispersed fine pores 20 with an average diameter of 45 nm or less.
And an upper layer (first layer) 18 made of. The refractive index n of the upper layer is the refractive index n of the SiO ₂ smooth film having no fine pores therein.
Is 1.46, while the volume ratio of air to the film by the fine holes 20 and the continuous volume ratio change of air to the outer surface due to the fine irregularities make the refractive index n about 1.32. ing.

The antireflection film 16 is formed by the process shown in FIG. That is, (a) is a diagram showing all steps, and (b) to (f) are explanatory diagrams of the main steps thereof.

First, the outer surface of the glass substrate 10 shown in (b) is washed with an alkaline detergent such as cerium oxide or an aqueous solution of NaOH to remove dirt and activate the outer surface. Then, the outer surface is preheated to 20 to 40 ° C.

This residual heat temperature is a temperature necessary for setting the film thickness of the lower layer subsequently formed on the outer surface to about d = λ / 4n and obtaining a uniform film thickness. In this case, if the temperature of the outer surface is less than 20 ° C., the evaporation of the alcohol component of the dispersion liquid applied to form the lower layer is delayed, and liquid is likely to accumulate in the peripheral portion, and the film thickness of the lower layer formed. Lacks uniformity. On the other hand, when the temperature exceeds 40 ° C., the evaporation rate of the solvent in the dispersion becomes too fast, and the film thickness at the central portion becomes thick and the film thickness at the peripheral portion becomes thin, resulting in poor uniformity of the film thickness.

Next, on the outer surface of the preheated glass substrate 10, an average particle size of 5 was added to an alcohol solution of ethyl silicate.
Ti O ₂ of less than _{0nm, Si O 2, Zn O} 2, Sn O 2,
A dispersion liquid in which high-refractive-index oxide fine particles 19 such as In ₂ O ₃ is stably dispersed is applied by a spin method, and then 20 to 20
After drying at 40 ° C., as shown in (c), an ethyl silicate film 21 for forming a lower layer containing the high refractive index oxide fine particles 20 and having a film thickness d = λ / 4n is formed.

In this case, in order to form a lower layer having a film thickness of about d = λ / 4n, it is necessary to add the high refractive index oxide fine particles 19 to the alcohol solution of ethyl silicate in an amount of 1 to 3%. is there. If the amount of the high refractive index oxide fine particles 19 added is less than 1%, it becomes difficult to control the film thickness on the entire surface of the glass substrate 10 even if the rotation speed during coating is slowed. On the other hand, if it exceeds 3%, the wettability of the dispersion liquid with respect to the outer surface of the glass substrate 10 deteriorates, radial uneven coating occurs, and a uniform smooth film cannot be obtained. In addition, 2 after applying the above dispersion liquid
Drying at 0 to 40 ° C. is an appropriate temperature for improving the wettability of the dispersion liquid for forming the upper layer to be subsequently applied onto the ethyl silicate film 21 containing the high refractive index oxide fine particles 19. It is necessary to completely remove the solvent at this temperature.

Next, the ethyl silicate film 21 containing the high refractive index oxide fine particles 19 heated to 20 to 40 ° C.
An alcohol solution of ethyl silicate was applied onto the above by a spin method, and then semi-dried at 20 to 40 ° C., and finally an average film thickness d = λ / 4n or so as shown in (d). To form a semi-dried upper layer film 22 made of ethyl silicate in which the water-soluble alcohol 22 having a boiling point of 90 ° C. or higher remains.

As the alcohol solution of ethyl silicate to be applied in this case, a 1% to 3% solution is used so that the average film thickness of the finally formed upper layer is about d = λ / 4n. Further, in order to form a film structure having fine uneven surfaces and fine pores therein, the boiling point of 1-propanol, ethoxyethanol, 1-butanol or the like is 9 relative to the total amount of the solvent.
30% of one or two or more water-soluble alcohols at 0 ° C or higher
An alcoholic solution of ethyl silicate mixed at a volume percentage of at least is used. In this case, when the amount of the water-soluble alcohol having a boiling point of 90 ° C. or higher is less than 30% by volume, the upper layer finally formed does not have a desired fine uneven surface or a film structure having fine pores therein. In addition, the semi-drying at 20 to 40 ° C. after applying the alcohol solution of ethyl silicate leaves water-soluble alcohol 22 having a boiling point of 90 ° C. or higher, evaporates the other solvent, and is used for subsequent water washing. On the other hand, it is necessary to make the film strength sufficiently endurable.

Next, the outer surface of the semi-dry upper layer film 23 was
The alcohol 22 remaining in the semi-dried upper layer film 23 is removed by immersing or spraying in water 24 (or warm water) at 0 ° C. or lower and washing. The cleaning time is 60 seconds or less.

In this case, it is important that the temperature of the washing water is 60 ° C. or less and the washing time is 60 seconds or less.
If it exceeds 0 ° C., the erosion effect becomes large even in a short time, the surface irregularities become large, and the pores formed inside the film become large. Similarly, when the cleaning time exceeds 60 seconds, the erosion effect becomes large, the surface irregularities and the pores formed inside the film become large, the light scattering becomes large, and not only the resolution deteriorates, but also The wear resistance of the film deteriorates.

Next, as shown in (f), water is drained and then baked at a temperature of 200 ° C. or higher to hydrolyze and condense the ethyl silicates of the upper and lower membranes 23 and 24 to obtain ethyl silicate. The film is made of high-refractive-index oxide particles 19
A lower layer 17 having a film thickness of d = λ / 4n of a structure bonded with iO _2.
And the semi-dried upper layer film 23 is an upper layer 18 having a structure film thickness d = λ / 4n in which the outer surface is a fine uneven surface and the fine holes 20 are present.
Then, the antireflection film 16 is formed.

By the way, when the antireflection film 16 is formed by the above method, the upper layer 18 has a refractive index of 1.46 with respect to the SiO ₂ smooth film having a volume ratio of air to film by the fine pores 20 and The refractive index can be about n = 1.32 due to the continuous volume ratio change between the air and the outermost layer (upper layer 18) due to the fine irregularities. As a result, by forming the upper layer 18 as a low refractive index layer in this way, a broadband and low reflectance reflectance spectrum can be realized in a two-layer structure, and in combination with the upper layer 18, the refractive index of the lower layer 17 is n. = 1.55
The film thickness can be 1.70 and the film thickness d can be 80 to 90 nm.
This means that when the lower layer is formed using a dispersion in which the high-refractive-index oxide fine particles 19 are stably dispersed in an alcohol solution of ethyl silicate, considering the abrasion resistance thereof, the high-refractive-index oxide fine particles 19 Increasing the content is disadvantageous because it deteriorates wear resistance, but for the lower layer 17 of the antireflection film 16 of this example, for example, when n = 1.55, SnO ₂ having an average particle size of 10 nm is used. Weight ratio with Si O ₂ (Sn O ₂ / S
It is sufficient to use a dispersion liquid having an iO ₂ weight ratio of 1.5, and when n = 1.70, TiO _{2 having} an average particle size of 40 nm is used.
The ratio of the _{Si O 2 (Ti O 2 /} Si O 2 weight ratio) 0.
A dispersion liquid of No. 5 may be used, and the abrasion-resistant lower layer 17 can be easily formed.

In FIG. 4, the high refractive index oxide fine particles 19 were converted into SiO ₂ by the above method, and the SiO ₂ fine particles / SiO _{2 were used.}
When the weight composition ratio of the thin film is 1.5, a lower layer 17 having a film thickness d of 90 nm is formed, and a surface roughness of 50 nm and an uneven pitch 2 are formed on the lower layer 17.
The relationship between each wavelength and the regular reflectance R (x) of the antireflection film 16 in which the upper layer 18 having an uneven surface of 000 nm and having the fine holes 20 of 40 nm in diameter is formed is shown. The curve 25a is the specular reflectance when the incident angle θ of the measurement light on the antireflection film is 0 °, and the curve 25b is the regular reflectance when it is 30 °.

In general, this antireflection film has a broad-band reflection spectrum, exhibits good antireflection properties with a regular reflectance of about 0.325%, and hardly deteriorates the resolution. Finally, the film could be fired at a temperature of 200 ° C. or higher to form a film having abrasion resistance and sufficient strength. Further, due to the fine uneven structure on the surface of the upper layer 18, the change in the reflection characteristics due to the change (error) in the film thickness is smaller than that when the upper layer is a smooth film, and the sol-gel method is a relatively simple film forming method. It can be easily formed. Further, in FIG. 5, the calculated value of the variation of the luminous regular reflectance R (lum) when the film thickness of the lower layer or the upper layer is deviated from the design value 26 by 10% is shown as the refractive index n of the upper layer.
As shown as a function of, by making the upper layer have a low reflectance, an antireflection film having excellent characteristics can be obtained.

In the above embodiment, the SiO ₂ fine particles were used as the lower layer high-refractive-index oxide fine particles, but as the lower-layer high-refractive-index oxide fine particles, transparent conductive materials such as Sn O ₂ , In ₂ O _{3 and the} like were used. When the oxide fine particles are used, an antistatic effect as well as an antireflection effect can be obtained.

In order to further lower the refractive index of the upper layer, a solution of ethyl silicate in MgF ₂ is added.
Fine particles are added to form fine pores inside and MgF
_An upper layer having a low refractive index can be formed by forming a film in which _two fine particles are bound with SiO ₂ .

In the above embodiment, the case where the antireflection film is formed on the outer surface of the panel of the color picture tube is described. However, the antireflection film forming method of the present invention forms the antireflection film of another display device. Can also be applied to.

[0044]

As a method for forming an antireflection film of a display device,
When forming a multilayer optical film of two or more layers having different refractive indexes on the outer surface of the glass substrate of the display surface, 30% by volume of water-soluble alcohol having a boiling point of 90 ° C. or higher was mixed with the solvent of the alcohol solution of ethyl silicate. An outermost layer is formed using a coating solution, and the outermost layer is washed with water at 60 ° C. or lower to remove alcohol components, whereby the surface of the outermost layer has an uneven pitch of 10 to 1000 nm and an uneven roughness of 10 to 50 nm. When the fine pores having an average diameter of 50 nm or less are present internally, the refractive index of the outermost layer is such that the volume ratio of air to the film due to the fine pores and the continuous volume ratio of air to the outermost layer due to the fine roughness. Due to the two effects of the change, the value can be reduced to a value that cannot be realized by an ordinary optical medium, and an antireflection film exhibiting a broadband reflection spectrum with a low reflectance can be obtained. Moreover, since the reflection spectrum is in a wide band, the change in reflectance due to the variation in film thickness can be suppressed mildly. As a result, even if the film is formed by a simple film formation method in which the film thickness control is insufficient, the increase in the reflectance due to the variation in the film thickness can be suppressed mildly, and the unevenness of the outermost layer is very fine. It is possible to prevent the deterioration of resolution by reducing the diffusion effect based on the unevenness.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a color picture tube according to an embodiment of the present invention.

FIG. 2 is a view showing the structure of an antireflection film formed on the outer surface of the panel.

FIG. 3 (a) is a process diagram showing a method for forming an antireflection film on the outer surface of the panel, and FIGS. 3 (b) to 3 (f) are each a method for forming an antireflection film shown in correspondence with the process diagram. It is a figure for explaining.

FIG. 4 is a diagram showing the relationship between the wavelength and regular reflectance of the antireflection film.

FIG. 5 is a diagram showing variations in the luminous regular reflectance of the antireflection film as a function of the refractive index of the outermost layer.

FIG. 6: S is added to a conventional alcohol solution of ethyl silicate.
The i O ₂ is a diagram illustrating a dispersed structure of the formed anti-reflection film by dispersion.

FIG. 7 is a diagram showing a structure of a conventional multilayer vapor deposition film.

[Explanation of symbols]

10 ... Panel 12 ... Phosphor screen 15 ... Electron gun 16 ... Antireflection film 17 ... Lower layer (second layer) 18 ... Upper layer (first layer) 19 ... High refractive index oxide fine particles 20 ... Micropores 23 ... High refractive index Ethyl silicate film containing fine oxide particles 24 ... Semi-dry upper layer film

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[Procedure amendment]

[Submission date] November 7, 1991

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0023

[Correction method] Change

[Correction content]

[0023]

In an antireflection film forming method for a display device, when forming a multilayer optical film having two or more layers having different refractive indexes on an outer surface of a glass substrate of a display surface, an alcohol solution of ethyl silicate is used. Boiling point 90 relative to solvent
The surface of the outermost layer is formed by forming the outermost layer using a coating liquid in which 30% by volume or more of water-soluble alcohol having a temperature of ℃ or more is mixed, and washing the outermost layer with water having a temperature of 60 ° C or less to remove alcohol components. Was used as an uneven surface having an uneven pitch of 10 to 1000 nm and an uneven roughness of 10 to 50 nm, and fine pores having an average diameter of 50 nm or less were included therein.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0029

[Correction method] Change

[Correction content]

First, the outer surface of the glass substrate 10 shown in (b) is washed with an alkaline detergent such as cerium oxide or an aqueous solution of NaOH to remove dirt and activate the outer surface. The pre heat the outer surface thereof to 20 to 40 ° C..

[Procedure amendment 4]

[Document name to be amended] Statement

[Name of item to be corrected] 0030

[Correction method] Change

[Correction content]

[0030] The preheat temperature is then the underlying film thickness to be formed on the outer surface, and d = λ / 4n order, and the temperature required for obtaining a uniform film thickness. In this case, if the temperature of the outer surface is less than 20 ° C., the evaporation of the alcohol component of the dispersion liquid applied to form the lower layer is delayed, and liquid is likely to accumulate in the peripheral portion, and the film thickness of the lower layer formed. Lacks uniformity. On the other hand, when the temperature exceeds 40 ° C., the evaporation rate of the solvent in the dispersion becomes too fast, and the film thickness at the central portion becomes thick and the film thickness at the peripheral portion becomes thin, resulting in poor uniformity of the film thickness.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0031

[Correction method] Change

[Correction content]

Next, on the outer surface of the glass substrate 10 heated above pre, average particle size 5 to an alcohol solution of ethyl silicate
Ti O ₂ of less than _{0nm, Si O 2, Zn O} 2, Sn O 2,
A dispersion liquid in which high-refractive-index oxide fine particles 19 such as In ₂ O ₃ is stably dispersed is applied by a spin method, and then 20 to 20
After drying at 40 ° C., as shown in (c), an ethyl silicate film 21 for forming a lower layer containing the high refractive index oxide fine particles 20 and having a film thickness d = λ / 4n is formed.

[Procedure Amendment 6]

[Document name to be amended] Statement

[Correction target item name] 0044

[Correction method] Change

[Correction content]

[0044]

As a method for forming an antireflection film of a display device,
When forming a multilayer optical film of two or more layers having different refractive indexes on the outer surface of the glass substrate of the display surface, 30% by volume or more of water-soluble alcohol having a boiling point of 90 ° C. or more is mixed with the solvent of the ethyl silicate alcohol solution. The outermost layer is formed by using the coating liquid prepared above, and the alcohol component is removed by washing the outermost layer with water at 60 ° C. or less, whereby the surface of the outermost layer has an uneven pitch of 10 to 1000 nm and an uneven roughness of 10 to 10. Fifty
When the surface has an uneven surface of nm and has fine holes with an average diameter of 50 nm or less, the refractive index of the outermost layer is such that the volume ratio of air to the film due to the fine holes and the continuous volume of air and the outermost layer due to the fine unevenness. Due to the two effects of the ratio change, the value can be reduced to a value that cannot be realized by an ordinary optical medium, and an antireflection film exhibiting a broadband and low reflectance reflectance spectrum can be obtained. Moreover, since the reflection spectrum is in a wide band, the change in reflectance due to the variation in film thickness can be suppressed mildly. As a result, even if the film is formed by a simple film formation method in which the film thickness control is insufficient, the increase in the reflectance due to the variation in the film thickness can be suppressed mildly, and the unevenness of the outermost layer is very fine. It is possible to prevent the deterioration of resolution by reducing the diffusion effect based on the unevenness.

Claims (1)

Claim: What is claimed is: 1. When forming a multilayer optical film of two or more layers having different refractive indexes on the outer surface of the glass substrate of the display surface, the boiling point is 90 ° C. with respect to the solvent of the alcohol solution of ethyl silicate.
The outermost layer is formed by using a coating solution prepared by mixing 30% by volume of the above water-soluble alcohol, and the outermost layer is washed with water at 60 ° C. or lower to remove the alcohol component. A method for forming an antireflection film for a display device, comprising an uneven surface having an uneven pitch of 10 to 1000 nm and an uneven roughness of 10 to 50 nm, and incorporating fine holes having an average diameter of 50 nm or less.