JPS63213245A - Substrate with anti-reflection coating - Google Patents

Abstract

PURPOSE:To decrease reflectance by providing an anti-reflection coating which a metal oxide thin film layer is made to chromoplast between a translucent substrate and a conductor pattern composed of a conductive metal. CONSTITUTION:The following units are provided: a translucent substrate 1, translucent thin film layer 2 composed of metal oxide arranged on the substrate, conductor pattern layer 3 arranged on the layer 2, and anti-reflection coating 2a which the layer 2 facing the layer 3 is made to chromoplast by a heat treatment. An incident outside light on the substrate 1 enters into a chromoplast coating 2a, is absorbed into the coating 2a, and attenuates, but some of the light proceeds to the outside of the substrate by reflecting on an interface with aluminum. At that time, some light is reflected on the interface between the substrate 1 and the layer 2a, is absorbed into the layer 2a, and reflectance decreases.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a substrate with an antireflection film that can be used for thin film EL elements, fluorescent display tubes, filters, and the like. The present invention will be explained below regarding a fluorescent display tube.

[Prior art]

As an anti-reflection coating for conventional fluorescent display tubes,
No. 115137 discloses an invention of a structure consisting of an antireflection film made of a colored thin film deposited on a transparent insulating substrate, and a wiring conductor and an anode conductor made of a metal thin film disposed on the antireflection film. .

However, the conventional example is an example in which the light emitted from the phosphor layer is applied to a front-emission type fluorescent display tube in which the light emitted from the phosphor layer is emitted from the other side of the substrate through the transparent insulating substrate. Therefore, if a colored thin film is present in a portion other than the anode conductor, the light emission of the phosphor layer is inhibited, so the colored thin film had to be stamped out by means of photolithography. In general, colored thin films contain many metal oxides and are difficult to etch, and since the anode conductor is aluminum, it is easy to etch and can be etched by both acid and alkali. It was not easy to improve the accuracy when etching was done in one go. Furthermore, etching twice increases the number of steps, which increases costs.

In addition, the fluorescent display tube shown in Fig. 3 is published in Japanese Patent Application Laid-open No.
It is described in No. 9, and ITOlI is placed on the substrate ll.
Transparent conductive oxide film 12 such as n, 03 and At) [13
This structure is characterized in that a composite electrode is formed by laminating the composite electrode layers, and the composite electrode layer is heat-treated in air or in a nitrogen atmosphere to blacken the interface of the composite electrode. In this conventional example, the blackened conductive oxide film 12 has an antireflection effect.

However, since this anti-reflection film 12 is a conductive film, it must be patterned in order to be used in a fluorescent display tube, and this problem is similar to that of the conventional example described above in which the anti-reflection film 12 is patterned using photolithography. There was a point.

In FIG. 3, 14 is an insulating layer, and 15 is a phosphor layer.

16 is a grid, 17 is a filamentary cathode, and 18 is an envelope.

[Object of the invention] The present invention forms a thin film of a metal oxide having transparent insulating properties, forms a wiring conductor and an anode conductor of a conductive metal on this thin film, and heat-treats the conductor so that they overlap with the conductive metal. The object of the present invention is to provide a substrate with an antireflection film that has an antireflection effect by coloring only a portion of the transparent insulating thin film.

[Structure of the invention]

In order to achieve the above-mentioned object, the present invention provides a transparent substrate and a transparent thin film layer made of a metal oxide disposed on the substrate. a conductor pattern layer; and the translucent M facing the conductor pattern layer.
It is characterized by having an antireflection film formed by coloring the III layer by heat treatment.

[For production]

External light incident on the transparent substrate enters the colored antireflection layer, where it is absorbed and attenuated.

A portion is reflected at the interface with aluminum and travels outside the substrate, and at this time, a portion is reflected at the interface between the substrate and the antireflection layer and absorbed by the antireflection layer.

In addition, if the thickness of the anti-reflection film is set to a certain appropriate value, the light reflected at the aluminum interface will interfere with the light reflected at the interface between the substrate and the anti-rht layer, weakening each other. The light intensity will be further reduced.

Furthermore, when reflected light exits from the substrate, some light is reflected by the surface of the substrate and absorbed into the substrate.

〔Example〕

The present invention will be described below with reference to embodiments shown in the drawings.

FIG. 1 shows an embodiment in which the antireflection coated substrate of the present invention is applied to a front-emission type fluorescent display tube.

The structure of the front-emitting type fluorescent display tube has a light-transmitting property, and a light-transmitting substrate 1 is used as a part of the envelope so that light emitted within the envelope can be observed through the substrate. An example of the transparent substrate 1 is a glass substrate. A light-transmitting thin film layer 2 of metal oxide is provided on the inner surface of this substrate 1. This metal oxide may be a thin film layer 2 that is transparent in a thin film state but has some color and has light transmitting properties. When subjected to various heat treatments, it becomes an oxygen-deficient metal oxide, and the transparent thin film layer becomes colored and changes into a colored thin film layer. Examples of metal oxides that have a powerful effect include titanium oxide, tungsten oxide, molybdenum oxide, vanadium oxide, and niobium oxide.

In this example, titanium oxide is used.

The light-transmitting thin film layer 2 of titanium oxide formed on the entire inner surface of the substrate 1 has a thickness of 500 to 600 nm, and is almost colorless and transparent. A mesh-like or stripe-like anode conductor 3 made of aluminum is formed on the surface of the transparent thin film layer 2.
a and a wiring conductor 3b connected from this anode conductor 3a to an external lead terminal are formed by batting, and these are collectively made into a conductor pattern layer 3. Note that the metal formed in the conductor pattern layer 3 may be any metal other than aluminum that is easily oxidized. The light-transmitting thin film layer 2 facing the conductive pattern layer 3 changes into a colored light-transmitting thin film layer by heat treatment, thereby forming an antireflection film 2a.

Next, a black insulating layer 4 is provided on the substrate except for the anode pattern portion including the anode conductor 3a.

A phosphor 5 is adhered to the anode pattern portion to constitute the anti-reflection coated substrate of the present invention.

In order to make a fluorescent display tube using this substrate with anti-reflection film, a grid 6 is arranged at a certain distance from the phosphor layer 5 of the above-mentioned anti-reflection substrate 1, and then a grid 6 is arranged at a certain distance from the grid 6. A filament-like cathode 7 is placed in a stretched structure, and the electrodes are covered with a container (not shown) and sealed to the substrate. After evacuating the gas in the container, the container is sealed in a high vacuum state to form a fluorescent display tube. Complete.

Next, a method for manufacturing the antireflection-equipped substrate of the present invention will be explained.

A thin film forming liquid containing several percent of an organic metal and consisting of a vehicle, eight agents, etc. is uniformly applied to one surface of a light-transmitting substrate 1, for example, a transparent glass substrate. An example of an organic metal is an organic titanium compound. Specific examples of organic titanium compounds include tetraalkoxytitanium compounds such as tetraisoproxytitanium (TPT) and tetra-n-butoxytitanium (TBT).

In addition, as a compound group of tetraalkoxytitanium polymers, tetraisopropoxytitanium monomer, tetra-n-butoxytitanium dimer, tetramer, heptamer, monomer, etc.
There is a 0-mer.

In addition, as a titanium acylate compound group, tree n-
There is a tetramer of butoxytitanium monostearate, polyhydroxytitanium stearate.

Furthermore, the titanium chelate compound group includes diisoproxy bisacetylacetonatotitanium (TAA),
di-n-butoxy bis(triethanolaminate),
Titanium (TAT), tetrakis(2-ethylhexanediorad)titanium (TOG), dihydroxy bis(lactato)titanium (TLA), and the like.

Such an organic titanium compound is generally liquid itself or soluble in an organic solvent, so that it can form a liquid thin film forming liquid. This thin film forming liquid can be uniformly applied to the back surface of the glass substrate 21 using a roll coater 20 as shown in FIG.

The glass substrate 21 is transported horizontally, as shown by the dashed line in FIG. When the glass substrate 21 reaches the top of the glass substrate 23, the transfer roller 22 stops, and the glass substrate 21 comes to a stop slightly tilted as shown by the solid line in FIG. Then, the lifting prevention ring 24 descends and comes into contact with the glass substrate 21.
The glass substrate 21 is pressed against the application roller 23. The application roller 23 has a receiver containing the thin film forming liquid 25 rotating clockwise in the tray 26, so that the thin film forming liquid is transferred to the application roller 23.
It sticks to 3 and is pumped out. Since the glass substrate 21 acts as a stopper for the pumped thin film forming liquid,
The liquid is collected in a wedge-shaped space between the glass substrate 21 and the application roller 23. After a certain period of time after the glass substrate 21 has stopped, that is, when a predetermined amount of the thin film forming liquid 25 has accumulated,
The glass substrate 21 is moved by a transfer roller 22 and an application roller 23.
Transported by.

The thin film forming liquid 25 is attached to the back surface of the glass substrate 21 by the method described above.

The glass substrate 21 contains organic titanium in an amount of 2% when converted to Tie 2, and has a thin film forming liquid 25 made of a vehicle or a solvent evenly adhered thereto. After gradual evaporation, 5
When held at 00-600℃ for 10 minutes, titanium oxide (T
ie, ) becomes a thin film. The thickness of this titanium oxide thin film is 500 to 600 mm, and the refractive index is required to be 2.1 or more.

Next, aluminum, which is a conductive metal, is deposited on the titanium oxide thin film by a known deposition method such as sputtering or vapor deposition. The thickness of the deposited aluminum thin film is approximately 1.1
It is on the order of μm. A resist is applied to the surface of the aluminum thin film 3, the resist layer is exposed to light to form a conductor pattern, and then an etching process is performed to dissolve unnecessary aluminum to form a conductor pattern. That is, a conductive pattern is formed using aluminum on the titanium oxide thin film 2 by means of photolithography.

Next, an anode segment is patterned using a black insulating layer 4 mainly composed of low-melting point glass.

That is, the black insulating layer 4 is formed by screen printing on the entire surface except for the anode segment portion where the phosphor layer 5 is formed.

Next, the black insulating layer 4 is fixed by a firing process, and the titanium oxide layer in contact with the aluminum conductor pattern 3 is colored blue. The firing temperature in this firing step is 520°C to 600°C, and the firing time is maintained for about 10 to 20 minutes.

The reason why the blue color develops through such heat treatment is thought to be as follows.

First, the light-transmitting thin film layer of metal oxide, that is, the titanium oxide layer in this example, contains organic titanium, which is an organic metal, on the order of several percent. When the titanium oxide is thinly deposited and fired in air at 500 to 600°C, only titanium oxide is formed on the substrate. Aluminum is deposited on the titanium oxide layer and heat-treated at 520 to 600°C, so that the aluminum in contact with the titanium oxide removes oxygen from the titanium oxide and oxidizes to become aluminum oxide. Titanium oxide, which has been deprived of oxygen by aluminum, is reduced to oxygen-deficient titanium oxide.

It is presumed that the formation of oxygen-deficient titanium oxide is the reason why the transparent titanium oxide layer becomes colored.

A titanium oxide thin film having a thickness in the range of 500 to 600 Å is suitable for low reflectance, but if the thickness is less than 500 Å, the colored layer will be too thin, resulting in little light absorption and high reflectance. Furthermore, when the film thickness is 600 Å or more, the light reflected at the aluminum interface and the light reflected at the interface between the substrate and the antireflection layer become less likely to interfere with each other, and their mutually weakening effects are reduced, resulting in a high reflectance as well.

In addition, it was necessary that the refractive index of the titanium oxide film be 2.1 or higher, but if the refractive index is lower than 2.1, the reflectance will be high although the color will change, and the anti-reflection effect will not work. It was experimentally found that it was small.

The temperature at which the titanium oxide layer on which the aluminum layer is disposed is fired and discolored is 520°C to 600°C, but 520°C
If the firing temperature is below 600'C, the reduction effect of titanium oxide will not be sufficient, the blue color will be pale, and the anti-reflection effect will be weak. become unable. If the substrate does not soften even at 600°C or higher, the firing temperature may be 600"C or higher, but if the temperature exceeds 650°C, the aluminum will start to melt and deform, so it is not recommended to fire at a temperature lower than that at which the aluminum will not deform. It becomes necessary.

The antireflection effect of the antireflective film-coated substrate formed by the method described above will be explained with reference to FIG.

Incident light A1 on the substrate 1, light A2 entering the inside of the substrate 1, and a part become reflected light A on the surface of the substrate 1 and go out to the outside.
The light A2 incident into the substrate 1 passes through the substrate 1 and the antireflection film 2.
At the interface of a, the light A is divided into the light A that enters the anti-reflection plate 142a and the light A that is reflected into the substrate 1. The light A4 incident on the anti-reflection film is reflected at the interface of the aluminum conductor pattern and becomes one reflected light A, which travels toward the outside of the substrate 1, but further reaches the anti-reflection film side at the interface between the anti-reflection film 2a and the substrate 1. Although some of the light is reflected by the substrate 1 and absorbed by the antireflection film, some of it exits the substrate 1 to the outside. However, the reflected light A6 reflected by the aluminum surface is absorbed by the antireflection film 2a and the glass substrate 1, but a part of it exits to the outside of the substrate 1. Then, the light reflected by another incident light B at the interface between the substrate 1 and the antireflection film and the reflected light A5 interfere with each other and weaken each other. Therefore, if the incident light is 100%, the reflected light is 4
is as follows.

FIG. 5 is a graph showing the relationship between light wavelength and reflectance. For comparison, the solid line shows the reflectance of a substrate without an anti-reflection film coated with Al or Minilam, which has a reflectance of 97 to 98%.6 The substrate with an anti-reflection film of the present invention has a reflectance of 400 nm.
The reflectance was 40% near +w, and gradually decreased up to about 650 nm, with a minimum value of 22%, and then gradually increased to about 23% at 800 nm.

〔Effect of the invention〕

As explained above, the anti-reflection film coated substrate of the present invention has an anti-reflection film made of a colored metal oxide thin film layer provided between a light-transmitting substrate and a conductor pattern made of a conductive metal. Therefore, it is possible to lower the reflectance due to the interference effect and absorption effect, and when used in a fluorescent display tube, it has the effect of improving the visibility of the display section even under high illuminance.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the main parts of a fluorescent display tube using the anti-reflection coated substrate of the present invention, FIG. 2 is a cross-sectional view explaining the reflection mechanism of incident light, and FIG. 3 is a conventional anti-reflection FIG. 4 is a sectional view of a film-coated fluorescent display tube, FIG. 4 is a sectional view of a roll coater for applying the antireflection film of the present invention, and FIG. 5 is a graph showing the relationship between wavelength and reflectance. 1...Transparent substrate 2...Transparent thin film layer of metal oxide 2a...Anti-reflection film 3...
...Conductor pattern layer patent applicant Futaba Electronics Industries Co., Ltd. No. 1
Figure 2

Claims (2)

[Claims] (1) A translucent substrate, a translucent thin film layer made of metal oxide deposited on this substrate, a conductor pattern layer disposed on this translucent thin film layer, and a conductor pattern layer that is opposite to this conductor pattern layer. 1. A substrate with an anti-reflection film, comprising: an anti-reflection film obtained by coloring the light-transmitting thin film layer by heat treatment. (2) The antireflection coated substrate according to claim 1, wherein the metal oxide is one selected from titanium oxide, tungsten oxide, molybdenum oxide, vanadium oxide, and niobium oxide.