JP2002062403A - Light absorbing antireflection body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To separately control the adjustment of transmittance and antireflection conditions without excessively improving the precision of thickness of each layer with respect to a light absorbing antireflection body formed on the display surface of an image display and having good contrast performance and a good effect of shielding a leakage electromagnetic field. SOLUTION: In a light absorbing antireflection body 10 comprising a light absorbing film 11 formed on a substrate 22 and an antireflection multilayer film 12 formed on the film 11 as a multilayer structure, a fine powder having a high refractive index is contained in the light absorbing film 11 and the refractive index of the film 11 is made equal to that of the substrate 22 by adjusting the content of the fine powder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light-absorbing anti-reflective member formed on a display surface of an image display device such as a cathode ray tube, and more particularly to a cathode ray tube using flat panel glass. And a light-absorbing anti-reflective body.

[0002]

2. Description of the Related Art In recent years, for example, a cathode ray tube (CDT) used as a computer display has been used.
With the flattening of the outer surface shape of the display surface (face panel), those having a large panel thickness difference between the center part and the corner part due to explosion-proof characteristics are becoming mainstream.

By the way, the cathode ray tube generally raises the light emission luminance of the fluorescent screen, lowers the reflectance at the interface between the panel and the fluorescent screen, or lowers the transmittance by the light absorption of the panel glass. , Good contrast is obtained. However, in the flattened cathode ray tube as described above, a difference in transmittance occurs due to a difference in thickness between the center portion and the peripheral portion of the panel, and thus the luminance uniformity in the central portion and the peripheral portion of the panel deteriorates. Could be done. Therefore, in order to obtain good contrast performance in a flattened cathode ray tube, it is necessary to increase the glass transmittance (to make it low-clear) and to impart light absorbing properties to a film formed on the surface of the panel glass. ,
It is essential to make the total transmittance equivalent, so that good contrast can be obtained.

As a film or the like formed on the surface of a panel glass, a light-absorbing anti-reflective body having a multi-layer structure and having functions of light-absorbing, anti-reflective and conductive properties is known (for example, see Japanese Patent Application Laid-Open No. H11-157556). JP-A-6-510382, JP-A-9-
No. 156964). These light-absorbing anti-reflective bodies exhibit properties other than contrast performance, such as an anti-reflection function utilizing the interference effect of light and a function of shielding electromagnetic waves generated from inside the cathode ray tube by conductivity. Has become.

[0005]

However, none of the conventional light-absorbing anti-reflection bodies can independently control contrast performance, anti-reflection performance, and conductive performance individually. For example, when the transmittance of the panel glass is increased and the transmittance of the light-absorbing antireflection body itself is decreased, an equivalent contrast is obtained.
For this purpose, the light absorbing layer in the light absorbing antireflective body needs to be thickened, so that light incident from the glass side (emission from the fluorescent screen of the cathode ray tube) is generated at the interface between the glass and the light absorbing antireflective body. It will be greatly reflected. Therefore, in this case, there is a possibility that the display image on the cathode ray tube may be seen twice.

On the other hand, for example, Japanese Patent Application Laid-Open No. 11-120
No. 943 discloses that in a thin film structure having a two-layer structure, light transmittance and reflection characteristics can be separately set depending on the thickness of each layer, that is, ruthenium fine particles of the two-layer structure are included. The value of the transmittance is varied by the thickness of the light absorbing layer, and the light absorbing layer is made conductive,
Further, it discloses that the phase of reflected light at each interface between the light absorbing layer and the outermost silica film is controlled by the optical film thickness so as to obtain low reflection characteristics. It is considered that forming a film with a small number of layers is advantageous from the viewpoint of productivity. However, as a constraint on the film thickness determined from the antireflection conditions, an accuracy of about ± 2% is required, whereas the accuracy of the film thickness required for adjusting the transmittance may be about ± 5 to 8%. That is, there is a demerit that the manufacturing margin of the film thickness uniformity with respect to the transmittance is limited by the antireflection condition of the antireflection function.

Accordingly, the present invention provides a light-absorbing reflection control device capable of individually controlling the transmittance adjustment and the antireflection conditions independently of each other without making the thickness of each layer unnecessarily high. It is intended to provide a preventive body.

[0008]

SUMMARY OF THE INVENTION The present invention is a light-absorbing anti-reflective body devised to achieve the above object, and comprises a light-absorbing film formed on a substrate constituting a display surface of an image display device. And an anti-reflection multilayer film formed of a multilayer structure on the light absorption film, and at least one of the layers is a conductive thin film, and attenuates reflected light with respect to incident light by light interference. In the antireflection body, the light absorbing film contains a high refractive index fine powder, and the refractive index of the light absorbing film is substantially equal to the refractive index of the base material by adjusting the content of the high refractive index fine powder. It is characterized by having been made.

In the light-absorbing anti-reflection body having the above-mentioned structure, the interface reflection between the outermost anti-reflection multilayer film and the air layer outside thereof, and the interface between the layers constituting the anti-reflection multilayer film. The anti-reflection conditions are set and low reflection characteristics are obtained by the light interference interaction of reflection and the interface reflection between the anti-reflection multilayer film and the light absorption film, but the reflection loss at the interface between the light absorption film and the substrate is obtained. Can be almost neglected because the refractive index between them becomes substantially equal by adjusting the content of the high refractive index fine powder. Therefore, when forming the light-absorbing anti-reflection body, it is possible to independently control the transmittance, the reflectance, and the like thereof.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A light-absorbing antireflection body according to the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing a schematic configuration of an example of a light-absorbing antireflection body according to the present invention, and FIG. 2 is a cathode ray tube (CRT; an example of an image display device using the light-absorbing antireflection body). Cathode Ra
y Tube).

Here, first, before describing the light-absorbing anti-reflection body according to the present invention, a cathode ray tube using the light-absorbing anti-reflection body will be briefly described. As shown in FIG. 2, the cathode ray tube includes a picture tube valve (funnel) 21 formed in a funnel shape, and a panel glass 22 provided with a fluorescent screen on an inner surface at an opening of the picture tube valve 21. It is installed. An electron gun 23 for emitting an electron beam is sealed at the rear end of the picture tube valve 21. Further, at the neck portion of the picture tube valve 21,
Deflection yoke 24 for deflecting an electron beam from electron gun 23
Is attached. The electron beam emitted from the electron gun 23 irradiates the phosphor screen of the panel glass 22 after being deflected by the deflection yoke 24.

In the cathode ray tube having such a configuration, the outer surface of the panel glass 22 is formed flat. An antireflection film 25 is formed on the outer surface of the panel glass 22 for the purpose of enhancing contrast. As the antireflection film 25, the light absorbing antireflection member described in the present embodiment is used.

Next, the schematic structure of the light-absorbing anti-reflection body will be described. As shown in FIG. 1, the light-absorbing anti-reflection body 10 is formed on the outer surface of a panel glass 22 of a cathode ray tube, and a light-absorbing film 11 disposed on the panel glass 22 and And an antireflection multilayer film 12 having a multilayer structure disposed on the light absorption film 11.

The light absorbing film 11 is, for example, 10 n
m, comprising a light-absorbing dry gel film having a physical thickness of at least m, and containing a high-refractive-index fine powder that is a colorless high-refractive-index material for adjusting an optical refractive index, as described in detail below. It is. Further, the light absorbing film 11 also contains organic or inorganic pigment fine particles as a coloring pigment component.

On the other hand, the anti-reflection multilayer film 12 attenuates reflected light with respect to incident light by light interference, and at least one layer of the multilayer structure has a surface resistance of 1000.
It is formed by a conductive thin film of Ω / □ or less. Specifically, taking the simplest two-layer structure as an example,
The antireflection multilayer film 12 includes a TiN (titanium nitride) film 12 a formed as a second conductive layer with a physical thickness of 12 nm on the light absorbing film 11, and a third outermost layer thereon ( A physical film thickness of 70 to 110 nm (for example, 8
5 nm) and a refractive index of 1.52 or less (for example, 1.52)
(SiO 2) film 12b.

Incidentally, the TiN film 12 is used as the conductive thin film.
In addition to a, for example, a transparent transition metal film such as ITO (tin-doped indium oxide), SnO2 (tin oxide), ZnOx (zinc oxide), or NbN (niobium nitride), or an Ag (silver) film It is conceivable to use a metal thin film such as Ni-Fe (nickel-iron alloy).

The anti-reflection multilayer film 12 is made of the above-mentioned T
Instead of a two-layer structure composed of the iN film 12a and the SiO2 film 12b, a multilayer structure of three or more layers, for example, ITO / SiO2 /
It may be composed of TiO2 / SiO2. With such a multilayer structure, it is possible to obtain low-reflection characteristics over a wider band.

Next, a description will be given of a method of forming the light absorbing anti-reflection member 10 having the above-described structure on the outer surface of the panel glass 22.

In forming the light-absorbing anti-reflection body 10, first, the light-absorbing film 1 is formed on the outer surface of the panel glass 22.
Form one.

As a raw material for forming the light absorbing film 11, a silica film sol-gel solution is used. That is, an alcohol is added to silicon alkoxide [Si (OC2H5) 4] to form a mixed solution, and water required for hydrolysis and an acid or alkali as a catalyst are added, and this is used as a starting material. And, in this solution, an inorganic or organic pigment component such as carbon black or alkali blue lake is blended as a coloring component, and tin oxide fine particles are blended as a colorless high refractive index material for adjusting the optical refractive index. A base paint is obtained by adding a very small amount of a solid dispersion material in a solution.

The alcohol added to the starting material may be any material in which the metal alkoxide can be dissolved, and may be methanol, ethanol, n-propyl alcohol, n-butanol, octanol, diacetone alcohol or the like. As a catalyst that promotes hydrolysis to prevent the formation of precipitates and the separation of liquid phase, one or a combination of two or more of hydrochloric acid, sulfuric acid, nitric acid, acetic acid, and ammonia is used. As the coloring component, a coloring agent such as a pigment is selected according to the characteristics of the cathode ray tube. However, it is difficult for the particle system to exceed 500 nm due to the limitation of the film thickness.
A particle size of １００100 nm is desired. Dielectric materials such as titanium oxide, zirconium oxide, aluminum oxide, and silicon nitride can be considered as the colorless high refractive index material in addition to tin oxide.
Ultrafine particles of 0 nm are desired. However, the colorless high-refractive-index material is a high-refractive-index fine powder having a bulk refractive index of 1.6 or more, such as tin oxide fine particles. As the dispersant in the coating solution, one or more of an anion, a cation, a nonionic surfactant, an epoxy resin, polyvinylpyrrolidone, and the like may be used.

That is, the light absorbing film 11 is made of an alcohol solution of a silicon alkoxide having a functional group of -OH group (alcohol group) and -OR group (alkoxyl group) as a starting material. A base paint is prepared by blending a component and a colorless high-refractive index material such as tin oxide fine particles, and further adding a small amount of a dispersant, and applying the base paint to the outer surface of the panel glass 22 of the cathode ray tube, At a temperature t (for example, t <160 ° C.).

As a method for forming the light absorbing film 11, which is a coating film of the base paint, for example, a wet coating method is employed. In this wet coating method, the spin coating method is most suitable for obtaining a uniform film thickness. In addition to the spin coating method, a roll coating method, a bar coating method, a dip coating method, a spray method, an estrusion method and the like can be used. However, the present invention is not limited to these forming methods.

After the formation of the light absorbing film 11, a second TiN film 12a is formed on the light absorbing film 11, and a third SiO 2 film 12b is formed thereon. As a result, on the outer surface of the panel glass 22, the light-absorbing antireflection body 10 in which the antireflection multilayer film 12 has a two-layer structure of the TiN film 12a and the SiO2 film 12b is formed.

As a method for forming the second and subsequent layers of the antireflection multilayer film 12, for example, DC active sputtering is employed. This DC active sputtering method,
This is best for obtaining a uniform film thickness distribution over a large area.
Then, by adopting a simple film configuration, it is possible to increase manufacturing productivity.

Each of the sputterings is performed at 0.1 to 1 P
The film is formed in the pressure-controlled atmosphere a. In addition,
The anti-reflection multilayer film 12 can be formed by using a sol-gel wet coating method other than the sputtering method. However, in order to obtain a conductive layer having a surface resistance of 1000Ω / □ or less (for example, the TiN film 12a), a sputtering method is preferable. Further, a film can be formed by a vacuum evaporation method, but the present invention is not limited to these film formation methods.

When the light-absorbing antireflection body 10 of the present embodiment is formed on the outer surface of the panel glass 22 by the above-described procedure, the compounding ratio of the colorless high-refractive-index material in the base paint, that is, A significant feature is that the refractive index of the light absorbing film 11 is adjusted as described below by adjusting the content of the colorless high refractive index material in the absorbing film 11.

Here, the relationship between the content of the colorless high refractive index material in the light absorbing film 11 and the refractive index of the light absorbing film 11 will be described in detail. FIG. 3 is an explanatory diagram showing a specific example of a base coating composition when forming a light absorbing film, and FIGS. 4 and 5 are explanatory diagrams showing an example of characteristics of the formed light absorbing film.

For example, as shown in FIG. 3, when the main solvent component of the base paint is selected and the pigment and the solvent ratio are fixed, tin oxide fine particles are used as a colorless high-refractive index material, and the condition of the mixing ratio is variable. The case where the light absorption film 11 is formed by the above is considered. As the variable conditions of the mixing ratio of the tin oxide fine particles, the weight ratio of tin oxide to silica solid content as a solid dispersion material is 20% (condition 1) and 30%, respectively.
(Condition 2) and 60% (Condition 3) will be exemplified.

A base paint under the above conditions 1 to 3 was prepared, and each of the base paints was a glass substrate having a refractive index of 1.52 (5 mm).
4 and 5 show the results of measuring the reflectance and the transmittance when spin-coated at a thickness of about 400 nm on the panel glass 22 of (thickness). From these results, it can be seen that when the mixing ratio of tin oxide is increased, the transmittance of the light absorbing film 11 is reduced, and the refractive index is increased. On the other hand, when the mixing ratio of tin oxide is reduced, on the other hand, the transmittance of the light absorbing film 11 is increased, so that the refractive index is reduced.

When the refractive index of the panel glass 22 and the refractive index of the light absorbing film 11 are compared, the compounding ratio of tin oxide is increased and the transmittance of the light absorbing film 11 is reduced. It can be seen that the larger the difference, the higher the reflectivity of the panel glass 22 and the light absorbing film 11 becomes. This is panel glass 2
This is because, when the refractive index difference between the light absorbing film 2 and the light absorbing film 11 increases, the reflection loss at the interface between them increases (see arrow A in FIG. 1).

Therefore, in the light-absorbing anti-reflection body 10 of the present embodiment, the refractive index of the light-absorbing film 11 becomes substantially equal to the refractive index of the panel glass 22 by setting the mixing ratio of tin oxide to 20%. As a result, the reflection loss at the interface between the panel glass 22 and the light absorbing film 11 is reduced. Specifically, since the refractive index of the bulk of tin oxide is about 1.6, the mixing ratio (weight ratio with respect to silica solid content) of the tin oxide is set to 20%, so that the light absorbing film 11 has Refractive index is 1.4
It is about 5 to 1.55, which is substantially equal to 1.52 which is the refractive index of the panel glass 22.

That is, in the light-absorbing anti-reflection body 10 of this embodiment, as shown in FIG.
Reflection at the interface with the second film 12b (see arrow B in the figure) and its S
The respective lights of the interfacial reflection between the iO2 film 12b and the second-layer TiN film 12a (see arrow C in the figure) and the interfacial reflection between the TiN film 12a and the light absorbing film 11 (see arrow D in the figure) Although antireflection conditions are set by interference interaction and low reflection characteristics are obtained, reflection loss at the interface between the light absorbing film 11 and the panel glass 22 can be ignored by the above-described refractive index adjustment. The rate can be controlled individually and independently.

The transmittance is controlled mainly by the thickness of the light absorbing film 11. The film thickness accuracy of the light absorbing film 11 when only the transmittance is controlled is about ± 5 to 8% as an allowable value, and the transmittance at this time can be kept within ± 2%. In applying a pigment-dispersed paint, generally, high-precision coating methods include a spin coating method and a roll coating method. However, as long as the required film thickness accuracy can be achieved, the present invention employs these film forming methods. It does not depend.

On the other hand, the control of the reflectance is mainly
This is performed depending on the thickness of the antireflection multilayer film 12. The antireflection multilayer film 12 utilizing optical interference requires strict management depending on the refractive index and the film thickness of the films to be stacked. In order to adjust the phase condition in which the light waves overlap, it is necessary to adjust the phase at the wavelength level of the light, and its accuracy is required to be about ± 2% in terms of film thickness. As a manufacturing process for forming a uniform film thickness distribution over a large area such as a cathode ray tube with the required accuracy, a sputtering method is suitable. Production can be realized.

As described above, the light-absorbing anti-reflection body 10 of the present embodiment is formed of the light-absorbing film 11 formed on the panel glass 22 and the multilayer structure on the light-absorbing film 11.
Further, at least one layer is made of a conductive thin film (TiN film 12).
a) The anti-reflection multilayer film 12 of FIG.
Therefore, if the light-absorbing anti-reflection body 10 is used for, for example, a flattened cathode ray tube, the influence of panel thickness accompanying the flattening of the outer surface shape of the face panel of the cathode ray tube is eliminated, and light absorption with low reflection is achieved. Thus, it is possible to provide a surface treatment film having a shielding effect of a leakage electromagnetic field by providing conductivity.
That is, surface treatment suitable for a flat cathode ray tube using low-clear glass can be realized.

In addition, in the light-absorbing anti-reflection body 10 of the present embodiment, the refractive index of the light-absorbing film 11 is adjusted to the refractive index of the panel glass 22 by adjusting the content of a colorless high-refractive-index material such as tin oxide fine particles. And almost the same. Therefore, the reflection loss at the interface between the light absorbing film 11 and the panel glass 22 can be almost neglected since the refractive indexes between them are substantially equal. That is, since the refractive index of the light absorbing film 11 can be easily adjusted by the weight ratio of the colorless high refractive index material, the management of the characteristics of the light absorbing antireflection body 10 can be greatly simplified. In addition, it can be easily combined with an existing production line, and does not require a special cost (such as a new additional device in a paint application process) for the above-described characteristic management.

Further, the light-absorbing antireflection body 1 of the present embodiment
0 means that the reflection loss at the interface between the light absorbing film 11 and the panel glass 22 can be almost neglected, so that light emission from the phosphor screen side is reflected at the film interface and the phosphor screen side is projected again by using low-clear glass. The problem of the double image due to the light absorption can be prevented by attenuating the light intensity by the light absorbing film 11.

Further, the light absorbing anti-reflection body 10 of the present embodiment forms the light absorbing anti-reflection body 10 because the reflection loss at the interface between the light absorbing film 11 and the panel glass 22 can be almost ignored. The transmittance and reflectivity of the light absorbing film 1
1 and the thickness of the antireflection multilayer film 12 can be controlled individually and independently. That is, even when the light absorption film 11 is formed by using the spin method, which is inferior in film thickness uniformity as compared with the sputtering method, film formation unevenness due to light interference can be prevented. Manufacturing margin when forming the absorptive anti-reflection body 10 can be increased.

Further, the light-absorbing antireflection body 1 of the present embodiment
Reference numeral 0 denotes a face panel of a cathode ray tube, because not only a colorless high-refractive index material such as tin oxide fine particles but also organic or inorganic pigment fine particles are blended in a base paint on which the light absorbing film 11 is based. When used as an anti-reflection film for
A selective absorption filter considering RGB luminance can be realized.
That is, since the degree of freedom in selecting a pigment is high, the body color of the cathode ray tube screen can be changed as desired. Also, since the degree of freedom to control the transmittance distribution of the cathode ray tube is large,
In particular, it is possible to suppress the red electron beam having low luminous efficiency, and it is possible to improve the focus performance.

In this embodiment, the case where the present invention is applied to a flat panel glass of a cathode ray tube has been described. However, the present invention is not limited to the application to a cathode ray tube, and for example, an LCD (Liquid Crystal Display). FED (Field Emiss), which is the same self-luminous display as the cathode ray tube
The present invention can be similarly applied to a flat glass panel of a display device such as an ion display.

[0042]

As described above, according to the light-absorptive antireflection body of the present invention, the refractive indices of the light-absorbing film and the substrate become substantially equal by adjusting the content of the high-refractive-index fine powder. The reflection loss at the interface between them becomes almost negligible. Therefore, for example, even when used in an image display device having a flat display surface, a display image does not appear double, good contrast performance can be provided, and a shielding effect of a leakage electromagnetic field can be reduced. It is possible to realize a surface treatment film having a certain thickness. Furthermore, since the refractive index of the light absorbing film can be easily adjusted by adjusting the content of the high refractive index fine powder, the transmittance adjustment and the antireflection conditions can be individually adjusted without making the thickness of each layer more than necessary. It becomes possible to control individually and independently, and the management of the characteristics in the light-absorbing antireflection body can be greatly simplified.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a schematic configuration of an example of a light-absorbing antireflection body according to the present invention.

FIG. 2 is a schematic perspective view showing an entire image of a cathode ray tube which is an example of an image display device using a light absorbing anti-reflection body.

FIG. 3 is an explanatory view showing one specific example of a base coating composition when forming a light absorbing film in a light absorbing anti-reflection body.

FIG. 4 is an explanatory diagram illustrating an example of characteristics of a formed light absorbing film, and is an explanatory diagram illustrating a distribution state of transmittance with respect to back side incident light.

FIG. 5 is an explanatory diagram illustrating an example of characteristics of a formed light absorbing film, and is an explanatory diagram illustrating a distribution state of a reflectance with respect to front side incident light.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Light absorption antireflection film, 11 ... Light absorption film, 12 ... Antireflection multilayer film, 12a ... TiN film, 12b ... SiO2
Film, 22: panel glass, 25: anti-reflection film

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01J 9/20 G02B 1/10 A H05K 9/00 Z F term (Reference) 2K009 AA05 AA06 AA07 BB02 CC02 CC03 CC14 CC42 DD02 DD04 EE03 4K029 AA08 AA09 BA46 BA60 BB02 BC03 BC07 BD01 CA05 DC05 DC34 DC39 FA01 5C028 AA10 5E321 AA21 GG11 GH01

Claims (5)

[Claims] 1. A light-absorbing film formed on a base material constituting a display surface of an image display device, and a multilayer structure formed on the light-absorbing film, and at least one of the layers is a conductive thin film. In a light-absorbing anti-reflective body comprising an anti-reflection multilayer film that attenuates reflected light with respect to incident light by light interference, the light-absorbing film contains a high-refractive-index fine powder,
A light-absorbing antireflective body, wherein the refractive index of the light-absorbing film is made substantially equal to the refractive index of the substrate by adjusting the content of the high-refractive-index fine powder. 2. The light-absorbing film having a refractive index of 1.45 to 1.45.
The light-absorbing anti-reflective body according to claim 1, wherein the number is 55. 3. The light-absorbing film is prepared by mixing a high-refractive-index fine powder having a bulk refractive index of 1.6 or more with an alcohol solution of silicon alkoxide having a functional group of —OH group and —OR group. The light-absorbing anti-reflective body according to claim 1, wherein the light-absorbing anti-reflective body is formed based on a base paint. 4. The light absorption according to claim 3, wherein when the high-refractive-index fine powder is tin oxide, the weight ratio of tin oxide to silica solids in the base paint is approximately 20%. Anti-reflective body. 5. The light-absorbing anti-reflective body according to claim 3, wherein organic or inorganic pigment fine particles are blended in the base paint.