JP2001159701A - Electrically conductive antireflection film and glass panel for cathode-ray tube coated with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrically conductive antireflection film which diminishes reflected light, enhances contrast, imparts superior antistatic property and electromagnetic wave shielding property, hardly undergoes a change of its reflectance and resistance by heat treatment in a sealing step and in an evacuation step and prevents the appearance of a ghost even when the film is formed on a glass substrate having high light transmittance. SOLUTION: The electrically conductive antireflection film comprises a colored layer containing at least one selected from gold, silver, elements of the platinum group and their compounds and a cobalt-containing inorganic pigment as a 1st layer and a transparent layer having a refractive index of 1.3-1.6 to visible light as a 2nd layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a conductive anti-reflection film,
This relates to a glass panel for a cathode ray tube having a coating formed on the outer surface of the face portion.

[0002]

2. Description of the Related Art Conventionally, a cathode ray tube has been required to reduce reflected light and improve contrast, and recently, it has been required to prevent static electricity and shield electromagnetic waves which affect a human body. ing.

[0003] Therefore, by forming a conductive anti-reflection film on the outer surface of the face portion of the glass panel which is the display surface of the cathode ray tube, the reflected light is reduced, the contrast is improved, and the anti-static and electromagnetic wave shielding are further reduced. Attempts have been made to add functionality.

For example, Japanese Patent Publication No. Hei 6-510382 discloses that
A layer containing NbN, a layer containing TiO ₂ ,
A conductive anti-reflection film comprising a layer containing SiO ₂ has been proposed. Japanese Patent Application Laid-Open No. 9-156964 discloses a layer mainly composed of a metal oxide selected from Ti, Zr and Hf in order from the substrate side. There has been proposed a conductive anti-reflection film comprising a layer mainly composed of Si, Si or a nitride of Si, and a SiO ₂ layer.

[0005]

The light transmittance of the glass panel for a cathode ray tube affects the brightness and contrast when an image is projected on the cathode ray tube. That is, the higher the light transmittance of the glass panel for a cathode ray tube, the higher the luminance, but the lower the contrast. Conversely, the lower the light transmittance of the glass panel, the higher the contrast,
Brightness decreases.

In recent years, a glass panel for a cathode ray tube having a flat outer surface of a face portion is becoming widespread. However, such a flat glass panel is intended to obtain a desired mechanical strength.
The radius of curvature of the inner surface of the face portion is designed to be small, and the thickness of the peripheral region is much larger than the thickness of the central region of the face portion.

Therefore, when such a flat glass panel is made of glass having a low light transmittance, the difference in the amount of light transmission due to the difference in thickness between the central portion and the peripheral portion of the face portion becomes large, and the central portion and the peripheral portion become large. This causes a luminance difference in the video of the part. Therefore, by manufacturing the glass panel from a glass having a high light transmittance (for example, 70% or more), the difference in transmittance between the central region and the peripheral region is reduced, and the outer surface of the face portion is coated with a colored film. Thus, attempts have been made to lower the light transmittance (for example, 40 to 60%) and improve the contrast.

[0008] Japanese Patent Application Laid-Open No. Hei 6-510382 and JP-A
Conductive anti-reflection film disclosed in JP-A-9-156964
Used a colored film such as NbN or TiN as the conductive layer.
Using such a colored film, the contrast of the cathode ray tube
A film with a transmittance of about 50% to improve
The geometric thickness of about 25nm and 8nm respectively
Is required, but the resistance value is sufficiently low. This is even more
In addition to colored film _TwoLaminated layers etc.
When a multilayer film is used, the surface reflectance is
It will be low enough.

However, the colored films of NbN and TiN are
The refractive index of visible light is 1.3-1.8, 2.5-, respectively.
3.7, and the visible light absorption coefficient was 1.4, respectively.
To 2.4 to 2.1 to 3.1 and have a strong light absorption property, so that the conductive anti-reflection film using this has a problem that the back surface reflectance is high.

When such a conductive anti-reflection film having a high back reflectance is coated on the outer surface of the face portion of a flat glass panel made of glass having a high light transmittance, the light of the phosphor on the inner surface of the cathode ray tube is formed. Since the light is reflected on the back surface of the conductive anti-reflection film and is again reflected on the inner surface of the cathode ray tube, an image due to the direct light from the phosphor and an image whose position is shifted due to the reflected light are simultaneously projected on the surface of the cathode ray tube. However, there is a disadvantage that the image looks double.

Further, when producing a cathode ray tube, after forming various kinds of functional films on a glass panel, it is frit sealed with a funnel and the inside is evacuated. The above heat treatment is performed. However, in the above-described conventional conductive anti-reflection film, the reflectance and the resistance value tend to fluctuate before and after the heat treatment, so that the desired reflectance and electromagnetic wave shielding ability may not be obtained.

Japanese Patent Application Laid-Open No. Hei 11-230863 discloses that T
A conductive anti-reflection film composed of a first layer made of metal fine particles of i and Cu and a _second layer made of SiO ₂ is disclosed. This conductive anti-reflection film reduces reflection, improves contrast, and charges. Although it has excellent ability in prevention and electromagnetic wave shielding, and has low backside reflectance, there is still a problem that the reflectance and the resistance value are easily changed by heat treatment.

[0013] The present invention has been made in view of the above circumstances, and can reduce reflected light and improve contrast, impart excellent antistatic properties and electromagnetic wave shielding properties, and before and after heat treatment in a sealing step and an exhausting step. The reflective anti-reflection film, which does not fluctuate in reflectance and resistance value and has a high light transmittance even when coated on a glass substrate, prevents the image from being seen as a double image. It is an object of the present invention to provide a coated glass panel for a cathode ray tube.

[0014]

The conductive antireflection film of the present invention includes two layers formed on a substrate, and when referred to as a first layer and a second layer in this order from the substrate, Layers of gold,
A coloring layer containing at least one selected from silver and platinum group elements and their compounds, and a cobalt-containing inorganic pigment, wherein the second layer is a transparent layer having a visible light refractive index of 1.3 to 1.7. Characterized in that it is a layer.

Further, the glass panel for a cathode ray tube of the present invention comprises:
A conductive anti-reflection film is formed to cover the outer surface of the face portion, and the average radius of curvature of the outer surface of the face portion is 10,000 mm or more in all radial directions through the center of the face portion,
Wavelength 550 nm when the thickness is converted to 10.16 mm
Is made of glass having a light transmittance of 70% or more, and the conductive anti-reflection film is referred to as a first layer and a second layer in this order from the face side. At least one element selected from the group consisting of
It is a colored layer containing a cobalt-containing inorganic pigment, and the second layer is a transparent layer having a visible light refractive index of 1.3 to 1.7.

[0016]

According to the present invention, the first layer, that is, the colored layer containing at least one element selected from the group consisting of gold, silver, and platinum group elements and their compounds, and the cobalt-containing inorganic pigment has a refractive index of 1.2 to 2 times. .5, the absorption coefficient of visible light is 0.05 to
A light-absorbing colored layer having a conductivity of 1.0,
It has the effect of improving the adhesion strength between the film and the base and reducing the surface reflected light and the back surface reflected light by the interference effect with the second layer. By the way, the platinum group element is
Ru, Rh, Pd, Os, Ir, Pt
Examples of the cobalt-containing inorganic pigment include cobalt blue (Co, Mg) O.Al ₂ O ₃ and cobalt green CoO.
-ZnO, Cerulean Blue 2 (Co, Mg) O.Sn
O _{2 and the} like are suitable. In particular, it is most desirable to use a layer containing Ru and cobalt blue as the first layer. The reason is that Ru has a feature that light absorption on the short wavelength side in the visible light region is strong and light absorption on the long wavelength side is weak. Conversely, cobalt blue has a weak light absorption on the short wavelength side and a long light absorption. This is because light absorption on the wavelength side is strong, and the layer containing Ru and cobalt blue has a very good light absorption balance.

This first layer has a geometric thickness of 70 to 2
Preferably, it is 50 nm. That is, if the geometric thickness of the first layer is too small, it is difficult to sufficiently exert the effect of reducing the front surface reflectance and the back surface reflectance. In particular, in the case of a glass panel for a cathode ray tube, if the backside reflectance of the film exceeds the reflectance (4.5%) of the glass, the image is more likely to appear double, but the geometric thickness of the first layer is less than 70 nm. Then, it is very difficult to suppress the back surface reflectance to 4.5% or less. Further, when the first layer is formed by a method using a liquid such as a spin coating method, it is technically difficult to make the thickness too large, and further, a gas phase is used such as a sputtering method. In the case of forming a film by the method, the thicker the film, the longer it takes, and it is not practical in terms of workability and cost.
A more preferred geometric thickness of the first layer is between 80 and 220 n
m, more preferred geometric thickness is 85-200 nm
It is.

The second layer has a refractive index of visible light of 1.3.
To 1.6, which have an effect of reducing front surface reflected light and back surface reflected light by an interference effect with the first layer.
The geometric thickness of the second layer is preferably 60 to 150 nm, and the materials to be used are silicon dioxide (SiO ₂ ), magnesium oxide (MgO), magnesium fluoride (MgF ₂ ), and fluoride. Calcium (Ca
F ₂ ), cerium fluoride (CaF ₂ ), aluminum fluoride (AlF ₃ ), and aluminum oxide (Al ₂ O ₃ ) are suitable. Particularly, the layer mainly composed of SiO ₂ is a transparent layer having a visible light refractive index of 1.4 to 1.6, and has an effect of reducing front surface reflected light and back surface reflected light by an interference effect with the first layer. This is preferable because it is excellent in cost, low in cost, and excellent in workability of film formation.

When a layer containing SiO ₂ as a main component is formed, using a coating solution containing a compound represented by (R ₁ ) _n M (OR ₂ ) _4-n as a main component, practically high film strength is obtained. Is preferred because In this equation, R ₁ :
Alkyl group, alkenyl group, aryl group, M: Si, R
₂ : an alkyl group, wherein n = 0 or 1. If necessary, fine particles of a mixture or composite oxide of an oxide containing a metal such as Ti, Sn, Sb, Al, Ce, and Zn;
Alternatively, a compound described in the above formula using these metals as M may be added.

Note that the above-mentioned visible light absorption coefficient means the logarithmic ratio of the light intensity before and after passing through an object. To explain using symbols, a is the radiant flux of the absorbed light absorbed by the object, i is the radiant flux of the incident light incident on the object, r is the radiant flux of the reflected light reflected on the object surface, and passes through the object. Assuming that the radiant flux of the transmitted light is t, the expression a = i−rt holds. According to Lambert-Bouguer's law, the logarithm of the ratio of the radiant flux t of the transmitted light to the radiant flux i of the incident light is proportional to the transmission distance x of the light passing through the object, so that ln (t / i) = − kx The relationship holds. The proportional coefficient k at this time is called an absorption coefficient. When a thin film is formed on a substrate, reflection at the surface of the thin film and reflection at the interface between the substrate and the thin film occur, and these two reflected lights interfere with each other.
The absorption coefficient k also affects the reflectivity of the thin film. When the absorption coefficient k is less than 0.05, when the thickness x of the thin film is the same,
The radiant flux t of the transmitted light is larger than the radiant flux i of the incident light, the coloring property is weak, and the contrast is poor. On the other hand, 1.
If it exceeds 0, the radiant flux t of the transmitted light becomes smaller than the radiant flux i of the incident light, the coloring property is too strong, the backside reflectance of the thin film increases, and the glass panel for a cathode ray tube made of glass having a high light transmittance. If a thin film is formed on the CRT, the image projected on the cathode ray tube will appear double.

The geometric thickness is to be distinguished from an optical thickness such as λ / 4 and means a thickness independent of wavelength.

Further, in the present invention, it is preferable that an underlayer having a refractive index of visible light of 1.7 or less is interposed between the base and the first layer. In other words, when the first layer is directly formed on the base, fine metal particles and pigment fine particles constituting the first layer are aggregated or repelled due to minute foreign matters or attached substances such as organic substances remaining on the base. However, when a base layer is interposed between the two, aggregation and repelling of metal fine particles and pigment fine particles in the first layer are significantly reduced.

This underlayer has a refractive index of visible light of 1.7 or less so as not to degrade each property of the conductive anti-reflection film formed by the first and second layers. Excellent, high strength and low cost, Si
O ₂ , Si, Ti, Sn, Sb, Al, Zr, C
A transparent layer made of a mixture or a composite oxide with a metal oxide such as e or Zn is suitable. In order to form a uniform film, the above-mentioned (R ₁ ) _n M (OR ₂ ) _4-n It is desirable to use a coating solution containing the compound represented by the formula as a main component.

On the other hand, if the thickness of the underlayer is too large, the surface reflectance and the back surface reflectance increase, and the film may be peeled off after the heat treatment.
Preferably, the geometric thickness is m.

In the present invention, in addition to the above two or three layers, if necessary, an additional thin film layer is appropriately provided for the purpose of improving the adhesion of the film or adjusting the color tone. It is also possible.

As a method for forming the conductive antireflection film of the present invention, a general thin film forming means can be used. For example, a spin coating method, a spray coating method, a sputtering method, a vacuum evaporation method, a CVD method, a sol-gel method and the like can be applied, but a thin film having a large thickness (for example, a
m) is most suitable for the spin coating method because it can be manufactured relatively inexpensively.

When the conductive anti-reflection film of the present invention is formed, the coating, drying and heat treatment steps may be repeated for each layer, or the layers may be sequentially coated and dried and then heat-treated collectively. good. In the case of a three-layer film, the base layer and the first layer may be sequentially applied and dried, and then heat-treated, and then the second layer may be applied, dried and heat-treated, or the base layer may be applied and dried. After the heat treatment, the first and second layers may be applied and dried, and then the heat treatment may be performed at once. The temperature of this heat treatment is
Considering the removal of the solvent from the coating solution and the formation on the panel glass for a cathode ray tube, the temperature is preferably 200 to 500 ° C.

[0028]

The present invention will be described below in detail based on examples and comparative examples.

Tables 1 to 5 show the material of each layer constituting the conductive antireflection films of the examples and comparative examples, and the geometric thickness.

[0030]

[Table 1]

[0031]

[Table 2]

[0032]

[Table 3]

[0033]

[Table 4]

[0034]

[Table 5]

The methods for producing the conductive antireflection films of Examples 1 to 8 and Comparative Example 2 in the table are as follows. First, glass having a minimum value of the average radius of curvature of the outer surface of the face portion (in all radiation directions passing through the center of the face portion) of 50,000 mm and a light transmittance of 80% at a wavelength of 550 nm when the thickness is converted to 10.16 mm. (A 21-inch size) was prepared. Next, a solution containing a predetermined amount of the film material of each layer is prepared, and the film material of each layer is sequentially applied to the outer surface of the face portion of the glass panel using a well-known spin coating method and dried, and then 450
Heat treatment was performed at 30 ° C. for 30 minutes.

The conductive antireflection film of Comparative Example 1 was formed on the outer surface of the face portion of the same glass panel for a cathode ray tube by using a magnetron sputtering apparatus in order to form each layer.

Incidentally, the above film was adjusted so that the total transmittance (sum of the transmittance of the film and glass) at a wavelength of 550 nm was 50%, and Ru + (Co, Mg) was used.
The layer of O.Al ₂ O ₃ is made of Ru and (Co, Mg) O.Al ₂
The thickness was adjusted by changing the ratio of O ₃ .

The thus obtained glass panels for a cathode ray tube with a film of the example and the comparative example were placed in a box-type electric furnace, and 450
C., heat treatment for 60 minutes, wavelength 550 before and after heat treatment
The surface reflectance and resistance value in nm and the rear surface reflectance after heat treatment were measured, and the film unevenness occurrence rate and the total number of black spots were examined. The results are shown in Tables 6 and 7.

[0039]

[Table 6]

[0040]

[Table 7]

As is clear from Tables 6 and 7, Examples 1 to
In the film No. 8, the change in the surface reflectance before and after the heat treatment was small, and the change in the resistance value was also small. Also, the backside reflectance is
Since the reflectance is lower than that of glass (4.5%), it is assumed that the image of the cathode ray tube does not appear double. Incidentally, the films of Examples 5 to 8 having the underlayer had a lower film unevenness occurrence rate and a smaller number of black spots than the films of Examples 1 to 4 having no underlayer.

On the other hand, the film of Comparative Example 1 had large fluctuations in the surface reflectance and resistance before and after the heat treatment, and had a high back surface reflectance. In the film of Comparative Example 2, the surface reflectance and the resistance value before and after the heat treatment varied greatly.

The surface reflectivity in the table is obtained by measuring 15 ° regular reflection using an instantaneous multi-reflectometer.
The resistance value is obtained by measuring the resistance between the electrodes with a tester by attaching electrodes to the center of both sides of the short side of the face portion of the glass panel with an ultrasonic solder. Further, the back surface reflectance is obtained by using an instantaneous multi-reflectance measuring device in consideration of the reflectance and absorptance of glass. Further, the film unevenness occurrence rate and the total number of black spots were determined by visually confirming the number of samples in which film unevenness of the first layer occurred and the total number of black spots by a transmitted light inspection by preparing 10 samples. Was.

[0044]

As described above, the conductive anti-reflection film of the present invention has excellent ability to reduce reflected light, improve contrast, prevent static charge and shield electromagnetic waves, and before and after heat treatment at 400 ° C. or more. Even if the reflectance or resistance value fluctuates little and the outer surface of the face part of the glass panel for a cathode ray tube with high light transmittance is coated, the backside reflectance is low, so that the image does not look double, especially It is suitable as a conductive antireflection film formed on a flat glass panel for a cathode ray tube having a flat outer surface of a face portion.

The conductive antireflection film of the present invention can be formed by a spin coating method, and the total number of films is basically two.
The desired characteristics can be obtained even though it is a layer, so it can be manufactured at a low cost and can be applied to various displays such as liquid crystal display substrates and plasma display substrates, which are subjected to high-temperature heat treatment after film formation, in addition to cathode ray tubes. it can.

Further, by interposing an underlayer having a visible light refractive index of 1.7 or less between the substrate and the first layer, the first colored layer can be formed without deteriorating the conductive antireflection characteristics. It is possible to suppress the occurrence of film unevenness and black spots.

Further, the glass panel for a cathode ray tube of the present invention comprises:
The flat panel has an average radius of curvature of the outer surface of the face portion of 10,000 mm or more in all radial directions passing through the center of the face portion, but has a light transmittance of 70% or more at a wavelength of 550 nm when the thickness is converted to 10.16 mm. Since it is made of glass, the difference in luminance between the central part and the peripheral part of the face part is small, and since the above-mentioned conductive antireflection film is formed by coating the outer surface of the face part, the surface reflectance is low and the contrast is high. Since it has excellent antistatic properties and electromagnetic wave shielding properties and has a low back surface reflectance, it is possible to obtain a cathode ray tube in which an image does not appear double.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C03C 17/36 G09F 9/00 309A G09F 9/00 309 313 313 H01J 29/88 H01J 29/88 G02B 1 / 10 A (72) Inventor Michiharu Eda 2-7-1, Hararashi, Otsu-shi, Shiga Prefecture Inside Nippon Electric Glass Co., Ltd. (72) Inventor Shigeyoshi Ito 2-7-1, Hararashi, Otsu-shi, Shiga Prefecture Nippon Electric Glass (72) Inventor Masanobu Kido 2-7-1 Hararashi, Otsu City, Shiga Prefecture Nippon Electric Glass Co., Ltd.

Claims (4)

[Claims] The present invention includes two layers formed on a substrate, and when referred to as a first layer and a second layer in this order from the substrate side, the first layer is composed of gold, silver, platinum group elements and their elements. And a coloring layer containing a cobalt-containing inorganic pigment, and the second layer has a refractive index of visible light of 1.3 to 1.3.
1.6. A conductive antireflection film, which is a transparent layer. 2. The conductive anti-reflection film according to claim 1, wherein a base layer having a refractive index of visible light of 1.7 or less is interposed between the base and the first layer. 3. A conductive anti-reflection film is formed on the outer surface of the face portion so that the average radius of curvature of the outer surface of the face portion is 10,000 m in all radial directions passing through the center of the face portion.
m, and the glass has a light transmittance of 70% or more at a wavelength of 550 nm when the thickness is converted to 10.16 mm. The conductive antireflection film includes a first layer, a second layer, The first layer is gold,
A colored layer containing at least one element selected from silver, platinum group elements and their compounds, and a cobalt-containing inorganic pigment, and the second layer is a transparent layer having a refractive index of visible light of 1.3 to 1.6. A glass panel for a cathode ray tube, which is a layer. 4. The glass panel for a cathode ray tube according to claim 3, wherein a base layer having a refractive index of visible light of 1.7 or less is interposed between the base and the first layer.