JP2001215303A - Conductive antireflection film and glass panel coated with that film for cathode ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a glass panel for a cathode ray tube having a conductive antireflection film applied on the outer surface of the face part such that the antireflection film can decrease the reflected light and improve the contrast, the film has excellent antistatic property and shielding ability against electromagnetic waves and excellent heat resistance, and has low reflectance on the back face of the film even when the film is applied on the outer surface of the face part of the flat glass panel. SOLUTION: The conductive antireflection film consists of four layers formed on the substrate, and they are, from the substrate side, a first layer as a conductive film layer essentially comprising one kind of transition metal nitrides, transition metal carbonitrides and transition metal carbonitride oxides, a second layer of a transparent layer having 1.4 to 2.3 refractive index and 0.5 to 250 nm geometric thickness, a third layer as a color film layer essentially comprising a transition metal oxide, and a fourth layer of a transparent layer having 1.4 to 1.6 refractive index and 50 to 140 nm geometric thickness.

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, cathode ray tubes have been required to reduce reflected light and improve contrast. Recently, it has been required to prevent charging and shield electromagnetic waves which have a bad effect on the human body. It is becoming.

[0003] Therefore, by forming a conductive anti-reflection film on the outer surface of the face of the glass panel, which is the image display surface of the cathode ray tube, the reflected light is reduced, the contrast is improved, and the antistatic and electromagnetic wave shielding are further prevented. It has been proposed to add the function of.

For example, Japanese Patent Publication No. 6-510382 proposes a conductive anti-reflection film composed of a layer containing NbN, a layer containing TiO _2, and a layer containing SiO ₂ in order from the substrate side.

Japanese Patent Application Laid-Open No. 9-156964 discloses that
In order from the substrate side, a conductive antireflection film comprising a layer mainly composed of a metal nitride selected from Ti, Zr and Hf, a layer mainly composed of Si or Si nitride, and a SiO ₂ layer is proposed. Have been.

[0006]

In the production of a cathode ray tube, after forming various functional films on a glass panel as a substrate, the funnel is frit-sealed and the inside is evacuated. In the sealing step and the exhausting step, a heat treatment at 400 ° C. or higher is performed.

However, the conductive anti-reflection film disclosed in Japanese Patent Application Laid-Open No. 6-510382 and Japanese Patent Application Laid-Open No. 9-156964 greatly reduces the reflected light on the outer surface of the face portion and has a colored layer. Therefore, the contrast of the cathode ray tube can be improved, but the heat resistance is insufficient, the reflectance and the resistance value are easily increased by heat treatment, and it is difficult to obtain the expected reflectance and electromagnetic wave shielding ability. .

Further, 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 brightness, but the lower the contrast, and conversely, the lower the light transmittance of the glass panel, the higher the contrast, but the lower the brightness.

In recent years, the outer surface of the face portion of the glass panel for a cathode ray tube has been flattened. However, as the outer surface of the face portion becomes flatter, the inner surface of the face portion is obtained in order to obtain a desired mechanical strength. Designed to have a small radius of curvature on the surface, compared to the thickness of the center of the face,
The peripheral part becomes very thick.

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 wall thickness between the central part and the peripheral part of the face part becomes large, and the central part and the peripheral part become large. This causes a luminance difference in the video of the part. Therefore, by making the glass panel from a glass with high light transmittance, it is possible to prevent the luminance of the peripheral part from being extremely lowered compared to the central part of the face part, and to form a colored film on the outer surface of the face part. Attempts have been made to improve contrast by coating.

However, the above-mentioned Japanese Patent Application Laid-Open No. Hei 6-510
The conductive anti-reflection film disclosed in Japanese Patent Publication No. 382 and Japanese Patent Application Laid-Open No. 9-156964 also has a problem that the effect of reducing the reflected light on the back surface of the face portion is small. Since the backside reflectance of a glass having a higher light transmittance is higher, the conventional conductive antireflection film as described above is coated on the outer surface of the face portion of a flat glass panel made of a glass having a higher light transmittance. Even if it is formed, it is not possible to reduce the back surface reflectance, and it is likely to cause a fatal defect that the image projected on the cathode ray tube appears double.

SUMMARY OF THE INVENTION It is an object of the present invention to reduce reflected light and improve contrast, to have excellent antistatic properties and electromagnetic wave shielding capabilities, and to have excellent heat resistance, and to provide a flat glass panel with a face portion. An object of the present invention is to provide a glass panel for a cathode ray tube in which a conductive anti-reflection film is formed on the outer surface of the face portion by coating the outer surface of the face portion even when the outer surface is coated.

[0013]

The conductive anti-reflection film of the present invention includes four layers formed on a substrate, and includes a transition metal nitride, a transition metal carbonitride, and a transition metal carbon nitride in order from the substrate side. A first layer which is a conductive layer mainly containing one kind of nitrided oxide; a transparent layer having a refractive index of 1.4 to 2.3;
A second layer having a geometric thickness of 250 nm, a third layer which is a colored film layer containing a transition metal oxide as a main component, a transparent layer having a refractive index of 1.4 to 1.6, and A fourth layer having a geometric thickness of 140 nm is provided.

Further, the glass panel for a cathode ray tube of the present invention comprises:
The conductive anti-reflection film including the four layers described above 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 in all radial directions passing through the center of the face portion.
000 mm or more, and is characterized by being made of glass having a light transmittance of 70% or more at a wavelength of 550 nm when the thickness is converted to 10.16 mm.

[0015]

The conductive antireflection film of the present invention will be described below in detail.

In the present invention, the first layer formed closest to the substrate is a conductive film mainly composed of one of transition metal nitride, transition metal carbonitride and transition metal carbonitride. It has conductivity, and has the effect of reducing front surface reflected light and back surface reflected light and widening the low reflection region in the visible light region by the effect of interference with other layers. Further, it has an effect of suppressing an increase in resistance value after heat treatment at 400 ° C. or more and improving contrast as a light absorbing film. As this layer, a film mainly composed of a metal selected from Ti, Zr, Hf, and Nb, a carbonitride, and a carbonitride oxide is suitable. In particular, a nitride of Ti, a carbonitride, It is preferable to use a film containing carbonitride oxide as a main component because a low reflection region in a visible light region is widened.

The second layer has a refractive index of 1.4 to 2.3.
A transparent layer of 0.5 to 250 nm (preferably 0.5 to 250 nm).
(100 nm), and has an effect of reducing front surface reflected light and back surface reflected light by an interference effect with other layers. The material of the first layer is made of SiO ₂ , Si ₃ N ₄ , SiON,
One selected from the group of Al ₂ O ₃ and AlON is suitable.

The third layer is a colored conductive layer containing a transition metal oxide as a main component, has conductivity, and reduces surface reflected light and back surface reflected light by an interference effect with other layers. It has the effect of widening the low reflection region in the visible light region. Further, it has an effect of suppressing an increase in resistance value after heat treatment at 400 ° C. or more and improving contrast as a light absorbing film. As this third layer, Ti, Zr, H
A film mainly containing an oxide of a metal selected from f, Nb, and Ni is suitable. In particular, when a film mainly containing an oxide of Ni in an oxygen-deficient state is used, low film in a visible light region is obtained. This is preferable because the reflection area becomes wider.

The fourth layer has a refractive index of 1.4 to 1.6.
Has a geometric thickness of 50 to 140 nm, and has an effect of reducing front surface reflected light and back surface reflected light by an interference effect with other layers. This fourth layer is preferably a SiO ₂ layer in consideration of film forming properties and production costs.

The geometric thickness in the present invention is λ
/ 4, etc., which means a thickness independent of wavelength. Further, in the present invention, in addition to the above-mentioned respective film layers, an additional thin film layer may be appropriately provided for the purpose of further improving the adhesion of the film or adjusting the color tone.

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 sputtering method, a vacuum evaporation method, a CVD method, a spin coating method, a sol-gel method, or the like can be applied, but the sputtering method is most preferable in consideration of easy area enlargement and easy control of the film thickness.

The glass panel for a cathode ray tube according to the present invention is of a so-called flat panel type in which the average radius of curvature of the outer surface of the face portion is limited to 10,000 mm or more in all radial directions passing through the center of the face portion. In view of the above, the radius of curvature of the inner surface is reduced, and the outer surface is coated with the above-described conductive antireflection film according to the present invention.

On the other hand, the value of the average radius of curvature of the outer surface is 100
In a glass panel of less than 00 mm, the outer surface of the face portion is slightly curved, and the radius of curvature of the inner surface can be increased, so that the above-described conductive antireflection film is not required. That is, such a glass panel for a cathode ray tube,
This is because the difference in thickness between the central portion and the peripheral portion of the face portion can be reduced, so that it is not necessary to use a glass having a high light transmittance, that is, a glass that easily reflects on the back surface.

Further, the glass panel for a cathode ray tube according to the present invention has a wavelength of 5 when converted to a thickness of 10.16 mm.
The light transmittance of the glass at 50 nm is limited to 70% or more. The reason is that when the flat panel glass as described above is manufactured from glass having a light transmittance of less than 70%, a difference in luminance occurs between the center portion and the peripheral portion of the face portion, and this is avoided.

[0025]

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

Table 1 shows that the conductive anti-reflection coatings of the examples (Sample Nos. 1 to 3) and the conductive anti-reflection coatings of the comparative example (Sample N).
o. 4). In each table, the film configuration of each sample, the surface reflectance before and after the heat treatment, and the resistance value are shown. Table 1 also shows the reflectance of the back surface of each sample after the heat treatment.

[0027]

[Table 1]

Each of the conductive antireflection films shown in Table 1 was prepared as follows.

First, as shown in FIG. 1, the minimum value of the average radius of curvature of the outer surface of the face portion (in all radial directions passing through the center of the face portion) is 50,000 mm, and the thickness is 10.
A glass panel (17-inch size) 10 for a cathode ray tube made of glass having a light transmittance of 80% at a wavelength of 550 nm when converted to 16 mm was prepared, and the outer surface of the face portion thereof was coated with a magnetron sputter coater. Conductive antireflection film 1 having a three-layer or four-layer structure as shown in FIG.
1 was formed. In the column of the film configuration in the table, the material of each film layer and the geometric thickness are shown.

Each of the samples thus obtained was placed in a box-type electric furnace, heat-treated at 450 ° C. for 60 minutes, and the surface reflectance and resistance before and after the heat treatment, and the rear surface reflectance after the heat treatment were measured.

As a result, in Example No. Each of the samples Nos. 1 to 3 is No. 1 as a comparative example. As compared with the sample No. 4, the increase in the surface reflectance and the resistance value at the wavelengths of 550 nm and 620 nm after the heat treatment was able to be suppressed. Moreover, in the embodiment, N
o. Since each of the samples Nos. 1 to 3 also has a low backside reflectance, it is presumed that if these samples are used for a glass panel for a cathode ray tube, an image will not appear double. In addition, since each sample has a colored layer, it can be understood that high contrast can be obtained.

The surface reflectance in each table is obtained by measuring 15 ° regular reflection using an instantaneous multi-reflectance measuring device.

The resistance value was obtained by attaching an electrode to the center of the short side of the face portion of the glass panel with an ultrasonic solder and measuring the resistance between the electrodes with a tester.

Further, the back surface reflectivity is obtained by using an instantaneous multi-reflectance measuring device in consideration of the reflectivity and absorptivity of glass.

[0035]

As described above, the conductive anti-reflection film of the present invention has excellent ability for reducing reflected light, improving contrast, preventing static electricity and shielding electromagnetic waves, and has excellent heat resistance.
Even if the surface reflectance and resistance after heat treatment of 400 ° C. or more are low and the outer surface of the face portion of the glass panel for a cathode ray tube having a high light transmittance is formed by coating, the back surface reflectance is low,
Since the image of the cathode ray tube can be prevented from being seen double, it is suitable as a conductive antireflection film.

The conductive anti-reflection film can be applied to various display substrates such as a liquid crystal display substrate and a plasma display substrate which are subjected to a high-temperature heat treatment after the film formation, in addition to the cathode ray tube.

Further, the glass panel for a cathode ray tube of the present invention is a flat panel in which the average radius of curvature of the outer surface of the face portion in all radial directions passing through the center of the face portion is 10,000 mm or more, but the thickness is converted to 10.16 mm. In this case, the light transmittance at a wavelength of 550 nm is made of glass having a transmittance of 70% or more, so that the difference in luminance between the central portion and the peripheral portion of the face portion is small.
Because the conductive anti-reflection film containing two layers is formed by coating, the surface reflectance is low, the contrast is high, it has excellent antistatic properties and electromagnetic wave shielding properties, and since the back surface reflectance is low, the image It is possible to obtain a cathode ray tube that does not look double.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a glass panel for a cathode ray tube.

[Explanation of symbols]

 10 Glass panel for cathode ray tube 11 Conductive anti-reflective coating

Claims (2)

[Claims] 1. A conductive film including four layers formed on a substrate and mainly composed of one of transition metal nitride, transition metal carbonitride, and transition metal carbonitride, in order from the substrate side A first layer which is a layer, a transparent layer having a refractive index of 1.4 to 2.3, a second layer having a geometric thickness of 0.5 to 250 nm, and coloring mainly composed of a transition metal oxide 3rd layer
, A transparent layer having a refractive index of 1.4 to 1.6,
A conductive anti-reflection film comprising a fourth layer having a geometric thickness of 0 nm. 2. The conductive anti-reflection film according to claim 1, which 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 1 in all radial directions passing through the center of the face portion.
A glass panel for a cathode ray tube, wherein the glass panel has a light transmittance of 70% or more at a wavelength of 550 nm when converted to a thickness of 10.16 mm or more.