JP2001201606A - Electrically conductive antireflection film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an electrically conductive antireflection film which reduces internal reflection as well as surface reflection when used on the surface of a flat cathode-ray tube, prevents ghost phenomenon and can separately control its light transmittance and electric conductivity at a low production cost by forming a transparent electric conductor layer as one of 1st and 2nd layers, a light absorbing layer as one of 1st, 2nd and 3rd layers except the electric conductor layer, a dielectric layer as another and a dielectric layer as a 4th layer. SOLUTION: A layer (light absorbing layer) comprising titanium carbide (TiC) as a 1st layer, a layer (electric conductor layer) comprising indium stannous oxide (ITO) as a 2nd layer, a layer comprising titanium dioxide (TiO2) as a 3rd layer and a layer comprising silicon dioxide (SiO2) as a 4th layer are successively laminated on a glass substrate G.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive antireflection film having an electromagnetic shielding effect formed on a surface of a cathode ray tube or the like, and more particularly to a conductive antireflection film of a type using a light absorbing layer. .

[0002]

2. Description of the Related Art Conventionally, antireflection and shielding of electromagnetic waves on the surface of a cathode ray tube have been performed by forming an antireflection film made of a transparent multilayer dielectric film on a glass substrate.
In this type of anti-reflection film, the number of layers constituting the anti-reflection film may be ten or more in order to widen the wavelength range of low reflection, and the manufacturing cost increases significantly with this. Recently, an antireflection film of a type using a light absorbing layer made of titanium oxynitride or the like has been used (Japanese Patent Laid-Open No. Hei 10-8734).
No. 8).

Recently, attention has been paid to a cathode ray tube having a surface having a shape close to a plane, and there is an urgent need to develop a conductive antireflection film to be formed on the surface of such a cathode ray tube. In such a flat CRT, the thickness of the central part and the peripheral part are greatly different in order to obtain mechanical strength, and the light transmittance of the glass material is greatly increased in order to make the light intensity from the phosphor screen uniform. Although it is said to be high, the light transmittance of the conductive anti-reflection film is the light transmittance of the glass material since the light transmittance as a whole cathode ray tube surface needs to be approximately the same value as the conventional one. Needs to be reduced as the number increases.

Therefore, in the prior art described in the above-mentioned publication, a titanium oxynitride film and a film containing silica as a main component, each having a predetermined thickness, are used as an antireflection film, and the reflectance to external light (hereinafter, referred to as “antireflection film”). (Referred to as surface reflectance) can be reduced to about 75% or less while maintaining a low value.

[0005]

However, when a light absorbing layer is used as an anti-reflection film, unlike the case where a dielectric layer is used, the surface reflectance and the reflectance for light from the internal phosphor screen (hereinafter referred to as the reflectance). (Referred to as internal reflectance).

[0006] For example, in the above-mentioned publication, the internal reflectivity becomes as large as about 16 to 20%. As a result, as shown in FIG. In addition to the light T1 that passes through the glass material (glass substrate) 12 and the antireflection film 11 as it is, the light is internally reflected at the interface between the glass material 12 and the antireflection film 11, and then internally reflected at the fluorescent layer 13 to prevent reflection. Since the light T2 transmitted through the film 11 is generated, a so-called ghost phenomenon occurs.

[0007] The present invention has been made in view of the above circumstances, and even when formed on the surface of a planar cathode ray tube,
It is an object of the present invention to provide an inexpensive conductive antireflection film which can sufficiently prevent external light from reflecting on the surface and also suppresses internal reflection from a low value to prevent occurrence of a ghost phenomenon.

Further, in general, it is necessary to provide a layer having a conductive function in the conductive antireflection film, and it is desirable that the conductive property can be controlled independently of the light transmittance determined by the light absorbing layer. Therefore, in addition to the above objects, the present invention also aims to provide a conductive antireflection film capable of independently controlling the conductivity and the light transmittance during film production.

[0009]

According to the present invention, a conductive antireflection film is formed on a glass substrate in the order of first
An anti-reflection film laminated from a layer to a fourth layer, wherein one of the first layer and the second layer is formed of a transparent conductive layer, and the first layer and the second layer are The other of us,
One of the third layer and the third layer is a light absorption layer, the other is a high refractive index dielectric layer, and the fourth layer is a low refractive index dielectric layer.

Also, the refractive index n of the high refractive index dielectric layer
Is 2.00 or more, and the refractive index n of the low refractive index dielectric layer is
Is preferably from 1.35 to 1.60. Further, it is preferable that the light absorbing layer is made of a material selected from oxides, carbides, oxycarbonitrides, and metals containing the transition metal. Further, the conductor layer is made of IT
It is preferable to be composed of O (stannic oxide indium) or SnO ₂ .

Here, as preferred specific embodiments of the above-mentioned layer constitution, for example, there are the following four layer constitutions. That is, as a first specific layer configuration, the first layer is T
iC layer, the second layer is an ITO layer, and the third layer is TiO ₂
Layer, the fourth layer being a SiO ₂ layer. As a second specific layer configuration, the first layer is a layer made of oxycarbonitride of Ti, the second layer is an ITO layer, and the third layer is TiO ₂
Layer, the fourth layer being a SiO ₂ layer.

In a third specific layer configuration, the first layer is an ITO layer, the second layer is a layer made of oxycarbonitride of Ti, the third layer is a TiO ₂ layer, and the fourth layer is a TiO ₂ layer. Layer is SiO
_{It has two} layers.

Further, as a fourth specific layer structure, the first layer is an ITO layer, the second layer is a TiO ₂ layer, the third layer is a layer made of Ti oxycarbonitride, Layer is Si
It is an O ₂ layer. Note that each layer described above includes each of the above-described materials as a main material, and does not necessarily mean that other impurities are completely excluded.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a conductive anti-reflection film according to an embodiment of the present invention will be described with reference to the drawings. The conductive antireflection film according to the embodiment of the present invention is formed on the surface of a cathode ray tube, and reduces surface reflection of external light on the surface of the cathode ray tube. The configuration is an anti-reflection film formed by laminating a first layer to a fourth layer on a glass substrate in order from the glass substrate side, wherein one of the first layer and the second layer is One of the first layer and the second layer, and the third layer, one of which is a light-absorbing layer, and the other is a dielectric layer having a refractive index n of 2.00 or more. And the fourth layer has a refractive index n of 1.35 to 1.60.
Made of a dielectric layer.

By adopting such a layer structure, the light transmittance of the entire film is set to an arbitrary value of about 40 to 80%, and the original surface antireflection effect can be maintained satisfactorily while preventing the light from the internal phosphor screen from being emitted. The reflectance (internal reflectance) can be reduced to 10% or less.

Moreover, since the conductive anti-reflection film is composed of a small number of layers such as four, the production equipment can be simplified, and the production cost can be reduced.

An important feature of the conductive antireflection film is that the conductive function is mainly provided not to the light absorbing layer but to the transparent conductive layer, so that the light absorbing function and the conductive function are provided in different layers. Like that. This has the effect that the conductivity and the light transmittance can be independently controlled. However, it does not exclude that the above-described light absorption layer has conductivity. The light absorbing layer is set to have a light transmittance of 45 to 80% with respect to light having a wavelength of 550 nm.

Further, it is more preferable that the light absorbing layer is made of a material selected from oxides, carbides, oxycarbonitrides, and metals containing the transition metal of the transition metal. The conductor layer is made of ITO or SnO.
More preferably, it consists of ₂ .

The transition metals mentioned above include titanium (Ti), chromium (Cr), nickel (Ni), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), and tantalum (Ta). ) Etc. are used. Further, SiO 4 constituting the fourth layer, which is the uppermost layer, is formed.
_{The two} layers function as a protective layer.

The method for forming the light absorbing layer is not particularly limited, and a CVD method, a sputtering method, or the like can be employed. Examples of the sputtering method include an RF sputtering method and a DC reactive sputtering method. In particular, it is desirable to use a DC reactive sputtering method and to use a mixed gas of nitrogen, a rare gas and an oxidizing gas as a sputtering gas.

Hereinafter, the conductive antireflection film of the present invention will be described in more detail with reference to examples using specific numerical values.

[0022]

Example 1 As shown in FIG. 1, a conductive anti-reflection film according to Example 1 was formed on a glass substrate G as a first layer made of titanium carbide (TiC) (light absorbing layer). A layer (conductor layer) made of indium tin oxide (ITO) as the second layer, and titanium oxide (TiO ₂ ) as the third layer.
Is formed by sequentially laminating a layer made of silicon oxide (SiO ₂ ) as a fourth layer. It should be noted that the halftone-dotted region means the light absorbing layer (FIG. 2).
The same applies to ４4).

Here, in Example 1, the optical constant of each layer (the refractive index (n) when the complex refractive index is represented by n-ik)
And extinction coefficient (k)) and geometric film thickness (nm)
Are shown in Table 1. The right side in Table 1 shows the surface reflectance, the internal reflectance, and the film transmittance of the conductive antireflection film of Example 1 with respect to light having a wavelength of 550 nm.

[0024]

[Table 1]

Further, the surface of the visible light region of the conductive anti-reflection film of Example 1, the internal reflection characteristics (the horizontal axis is the wavelength of incident light (nm), the left vertical axis is the light reflectance (%)) and the light FIG. 5 shows the transmittance (the right vertical axis shows the light transmittance (%)). The measurement in this case is performed by measuring the spectral reflectance when the measuring light is incident on the conductive antireflection film at an incident angle of 5 ° (5 ° reflection measurement; Examples 2 to 5 below). 4 and Comparative Example).

<Embodiment 2> As shown in FIG. 2, a conductive antireflection film according to Embodiment 2 is formed on a glass substrate G as a first layer made of titanium oxycarbonitride (TiCON) (light absorbing layer). ) As indium tin oxide (ITO) as the second layer
, A layer made of titanium oxide (TiO ₂ ) as a third layer, and a layer made of silicon oxide (SiO ₂ ) as a fourth layer.

Here, in Example 2, the optical constant of each layer (the refractive index (n) when the complex refractive index is represented by n ± ik)
And extinction coefficient (k)) and geometric film thickness (nm)
Are shown in Table 2. The right side in Table 2 shows the surface reflectance, the internal reflectance, and the film transmittance of the conductive antireflection film of Example 2 with respect to light having a wavelength of 550 nm.

[0028]

[Table 2]

Further, the surface of the conductive antireflection film of Example 2 in the visible light region, the internal reflection characteristics (the horizontal axis is the wavelength of incident light (nm), the left vertical axis is the light reflectance (%)) and the light FIG. 6 shows the transmittance (the right vertical axis shows the light transmittance (%)).

<Embodiment 3> As shown in FIG. 3, a conductive antireflection film according to Embodiment 3 is formed on a glass substrate G as a first layer made of indium tin oxide (ITO) (conductor). Layer) as the second layer, titanium oxycarbonitride (TiCON)
, A layer made of titanium oxide (TiO ₂ ) as a third layer, and a layer made of silicon oxide (SiO ₂ ) as a fourth layer.

Here, in Example 3, the optical constant of each layer (the refractive index (n) when the complex refractive index is represented by n ± ik)
And extinction coefficient (k)) and geometric film thickness (nm)
Are shown in Table 3. The right side in Table 3 shows the surface reflectance, the internal reflectance, and the film transmittance of the conductive antireflection film of Example 3 with respect to light having a wavelength of 550 nm.

[0032]

[Table 3]

Further, the surface of the visible light region of the conductive anti-reflection film of Example 3 and its internal reflection characteristics (the horizontal axis is the wavelength of incident light (nm), the left vertical axis is the light reflectance (%)) and the light FIG. 7 shows the transmittance (the right vertical axis shows the light transmittance (%)).

<Embodiment 4> As shown in FIG. 4, a conductive antireflection film according to Embodiment 4 is formed on a glass substrate G as a first layer made of indium tin oxide (ITO) (a conductor). Layer), a layer made of titanium oxide (TiO ₂ ) as the second layer, a layer (light absorbing layer) made of titanium oxycarbonitride (TiCON) as the third layer, and silicon oxide (S) as the fourth layer.
iO ₂ ).

Here, in Example 4, the optical constant of each layer (refractive index (n) when the complex refractive index is represented by n ± ik)
And extinction coefficient (k)) and geometric film thickness (nm)
Are shown in Table 4. The right side in Table 4 shows the surface reflectance, the internal reflectance, and the film transmittance of the conductive antireflection film of Example 4 with respect to light having a wavelength of 550 nm.

[0036]

[Table 4]

Further, the surface of the conductive anti-reflection film of Example 4 in the visible light range, the internal reflection characteristics (the horizontal axis is the wavelength of incident light (nm), the left vertical axis is the light reflectance (%)) and the light FIG. 8 shows the transmittance (the right vertical axis shows the light transmittance (%)).

<Comparative Example> As a comparative example, the one described in JP-A-10-87348 was used.

That is, the conductive anti-reflection film of the comparative example
Titanium nitride (TiN _x ) as a first layer on a glass substrate
, A layer made of silicon nitride (SiN _x ) as a second layer, and a layer made of silicon oxide (SiO ₂ ) as a third layer. The geometric thickness of each layer is 18 nm for the first layer, 9 nm for the second layer,
The third layers are each set to 72 nm.

In this comparative example, the surface reflectance, the internal reflectance and the film transmittance for light having a wavelength of 550 nm were 0.53%, 16.62% and 55.48%, respectively. Furthermore, the surface and internal reflection characteristics in the visible light region of the conductive antireflection film of this comparative example (the horizontal axis is the wavelength of incident light (n
m) and the vertical axis shows the light reflectance (%) in FIGS. 9 and 10.

In this comparative example, since both the light absorbing function and the conductive function are provided to the titanium nitride layer as the first layer, it is difficult to independently control the light transmittance and the conductivity.
Table 5 summarizes the surface reflectance, the internal reflectance, and the film transmittance for light having a wavelength of 550 nm for each of Examples 1 to 4 and Comparative Example described above.

[0042]

[Table 5]

As is clear from Table 5 and FIGS. 5 to 10, in the conductive anti-reflection film of this embodiment, the film transmittance can be set to an optimum value for a planar cathode ray tube, and the surface reflectance can be adjusted. While maintaining a low value of, the internal reflectance can be significantly reduced.

The conductive anti-reflection film of the present invention is not limited to the above-described embodiment, and for example, an SnO ₂ layer can be used as the conductor layer. Further, the light absorbing layer can be made of various materials selected from transition metal oxides, carbides, oxycarbonitrides, and metals containing the transition metal, instead of those of the embodiment. . Further, the film thickness and the like of the embodiment can be appropriately changed.

[0045]

As described above, the conductive anti-reflection film of the present invention comprises a four-layer light anti-reflection film formed on a glass substrate. One of the first and second layers is composed of a transparent conductive layer, and the other is a light absorbing layer, and the other is a dielectric layer having a refractive index n of 2.00 or more. And the fourth layer has a refractive index n
Are composed of 1.35 to 1.60 dielectric layers. With such a configuration, it is possible to greatly reduce the internal reflectance while maintaining the surface reflectance at a low value in a state where the film transmittance is set to a predetermined value. When the refractive index n of the high-refractive-index dielectric layer is smaller than 2.00, it becomes difficult to obtain a desired reflectance-reducing effect.

This makes it possible to prevent the occurrence of a ghost image, which has been a problem in the prior art, while satisfying the conditions as a conductive anti-reflection film formed on a planar cathode ray tube. Since the number is small, the manufacturing cost can be reduced.

Further, by providing the conductive function mainly to the transparent conductive layer instead of the light absorbing layer, the light absorbing function and the conductive function are provided to different layers. This makes it possible to independently control the conductivity and the light transmittance.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a layer configuration of a conductive anti-reflection film according to Example 1 of the present invention.

FIG. 2 is a schematic diagram showing a layer configuration of a conductive anti-reflection film according to Example 2 of the present invention.

FIG. 3 is a schematic diagram illustrating a layer configuration of a conductive anti-reflection film according to a third embodiment of the present invention.

FIG. 4 is a schematic diagram showing a layer configuration of a conductive anti-reflection film according to Example 4 of the present invention.

FIG. 5 is a graph showing reflection characteristics (surface reflection and internal reflection) and light transmittance of the conductive antireflection film according to Example 1 of the present invention.

FIG. 6 is a graph showing reflection characteristics (surface reflection and internal reflection) and light transmittance of a conductive anti-reflection film according to Example 2 of the present invention.

FIG. 7 is a graph showing reflection characteristics (surface reflection and internal reflection) and light transmittance of a conductive anti-reflection film according to Example 3 of the present invention.

FIG. 8 is a graph showing reflection characteristics (surface reflection and internal reflection) and light transmittance of a conductive anti-reflection film according to Example 4 of the present invention.

FIG. 9 is a graph showing surface reflection characteristics of a conductive anti-reflection film according to a comparative example.

FIG. 10 is a graph showing internal reflection characteristics of a conductive antireflection film according to a comparative example.

FIG. 11 is a diagram for explaining a problem of the related art.

[Explanation of symbols]

 G, 12 Glass substrate 11 Anti-reflection film 13 Fluorescent layer

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masayuki Okaba 1-3324 Uetakecho, Omiya City, Saitama Prefecture Inside Fuji Photo Optical Co., Ltd. (72) Inventor Hiroaki Nakaoka 700, Konakacho, Sano City, Tochigi Prefecture F-term (reference) in Kiki Co., Ltd. 2K009 AA07 BB02 CC03 CC14 DD04 EE03

Claims (8)

[Claims] 1. An anti-reflection film formed by laminating a first layer to a fourth layer on a glass substrate in order from the glass substrate side, wherein one of the first layer and the second layer is provided. Comprises a transparent conductor layer, and the other of the first layer and the second layer, and the third
A conductive anti-reflection film, wherein one of the layers is a light absorption layer, the other is a dielectric layer having a high refractive index, and the fourth layer is a dielectric layer having a low refractive index. 2. The high refractive index dielectric layer has a refractive index n of 2.00 or more, and the low refractive index dielectric layer has a refractive index n of 1.35 to 1.60. The conductive antireflection film according to claim 1, wherein 3. The light absorbing layer according to claim 1, wherein the light absorbing layer is made of a material selected from oxides, carbides, oxycarbonitrides, and metals containing the transition metal.
Or the conductive antireflection film according to 2. 4. The conductive anti-reflection film according to claim 1, wherein the conductive layer is made of ITO or SnO ₂ . 5. The method according to claim 1, wherein the first layer is a TiC layer, and the second layer is an IC layer.
TO layer, the third layer is a TiO ₂ layer, and the fourth layer is SiO
The conductive anti-reflection film according to claim 1, wherein the film has _two layers. 6. The first layer is a layer made of Ti oxycarbonitride, the second layer is an ITO layer, the third layer is a TiO ₂ layer,
The conductive anti-reflection film according to claim 1, wherein the fourth layer is a SiO ₂ layer. 7. The first layer is an ITO layer, and the second layer is a T layer.
i a layer made of oxycarbonitride, wherein the third layer is a TiO ₂ layer,
The conductive anti-reflection film according to claim 1, wherein the fourth layer is a SiO ₂ layer. 8. The method according to claim 1, wherein the first layer is an ITO layer, and the second layer is a T layer.
an iO ₂ layer, wherein the third layer is a layer made of Ti oxycarbonitride;
The conductive anti-reflection film according to claim 1, wherein the fourth layer is a SiO ₂ layer.