JP2002015687A - Image display equipment and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reliable image display equipment which excels in adherence between a substrate and a side wall, and vacuum seal characteristics. SOLUTION: Concerning the image display equipment, within a vacuum envelope 1 which consists of a rear substrate 4 and a front substrate 5 estranged and arranged in parallel, carries out displays by carrying out excitation of luminescence of a phosphor screen 3 formed on an inside surface of the front substrate 5 with an electron beam emitted from two or more electron emission elements 2 arranged and formed on an inside surface of the rear substrate 4. The rear substrate 4 and the front substrate 5 are adhered and vacuum-sealed by an adhesive-cum-sealing agent 9 which consists of an indium alloy containing at least one element chosen from a group of silver, copper, hold, aluminum and antimony.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display device using a cold cathode type electron-emitting device and a method for manufacturing the same.

[0002]

2. Description of the Related Art An image display apparatus using a cold cathode type electron-emitting device displays an image by exciting a phosphor screen with an electron beam emitted from a large number of electron-emitting devices arranged in a matrix. And the whole can be formed into a thin flat plate, so FPD (Flat Panel Dispay)
Has attracted much attention as a display panel. As a specific structure of this image display device, a vacuum envelope is constituted by a rear substrate and a front substrate made of glass which are spaced apart and almost in parallel, and a large number of electron-emitting devices are formed on the inner surface of the rear substrate. The phosphor screens are arranged in a matrix and arranged on the inner surface of the front substrate. The back substrate and the front substrate face each other via a plate-like side wall arranged at a peripheral portion.

In manufacturing such an image display device, an exhaust pipe is provided on the rear substrate to keep the inside of the vacuum envelope at a high vacuum, and exhaust is performed by a vacuum pump while performing baking. However, since the front substrate and the rear substrate are arranged close to each other, it is extremely difficult to exhaust to a high vacuum state in a short time. As a method for solving such a problem, in a vacuum device, the entire vacuum device is evacuated to a high vacuum while baking both substrates with the front substrate and the rear substrate separated sufficiently, and a predetermined degree of vacuum is reached. Then, there is a method of joining the front substrate and the rear substrate via the side wall. This method requires a joining and sealing material or joining technique that can be used at high temperatures of 300 to 400 ° C. under high vacuum. For example, the bonding and sealing material has sufficient bonding strength for bonding the substrate and the side wall, the gas release from the bonding and sealing material at high temperature and high vacuum is small, High wettability is maintained,
It is required that the joining and sealing material pool and the joining and sealing material do not flow out of a predetermined position or fall off.

Generally, metals such as indium and gallium are used for joining or vacuum sealing glass members which cannot use an organic joining and sealing material.
This is because these metals exhibit wettability with glass when the temperature is raised to the melting point or higher. A metal having physical properties such as mercury that is repelled from the glass surface even when it is melted does not satisfy the requirements for such joining of glass members and vacuum sealing.

However, when a metal such as indium or gallium is used as a joining and sealing material for joining the rear substrate and the front substrate to the side wall in the above-described image display device, the melting point is much higher than the melting point as described above.
Since heat treatment at a high temperature such as 00 to 400 ° C. is imposed, the wettability of these metals to glass is reduced, and a problem arises in that a sufficient bonding or sealing effect cannot be exhibited.

[0006]

As described above, in a flat panel display using a cold cathode type electron-emitting device, a bonding and sealing material used for bonding between a substrate made of glass and a side wall and for vacuum sealing is used. When the wettability to glass is reduced by the high-temperature heat treatment, sufficient bonding and vacuum sealing performance cannot be maintained, and there is a problem that reliability is reduced.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a highly reliable image display device having excellent bonding and vacuum sealing performance between a substrate and a side wall, and a method of manufacturing the same.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a vacuum envelope comprising a rear substrate and a front substrate which are spaced apart and substantially parallel to each other, and an array formed on the inner surface of the rear substrate. In the image display device having a plurality of electron-emitting devices, and a phosphor screen formed on the inner surface of the front substrate and excited by the electron beam emitted from the electron-emitting device to emit light, silver, copper, gold, The back substrate and the front substrate are joined via an indium alloy layer containing at least one element selected from the group consisting of aluminum and antimony.

The vacuum envelope may further include a partition interposed between the rear substrate and the front substrate. In this case, at least one of the rear substrate and the front substrate and the partition are formed of an indium alloy. Joined through layers.

Further, according to the present invention, when manufacturing such an image display device, silver, copper, gold, indium is added to a predetermined position on the inner surface of at least one of the rear substrate and the front substrate.
An indium alloy to which at least one element selected from the group consisting of aluminum and antimony is added is placed and melted at a predetermined temperature, for example, at a temperature of 160 ° C. or more, and the indium alloy is welded, and then baked in a vacuum The method is characterized in that the back substrate and the back substrate are joined by the indium alloy through a process.

When the vacuum envelope further has a partition wall interposed between the rear substrate and the front substrate, the partition wall glass plate having substantially the same thermal expansion characteristics as at least one of the rear substrate and the front substrate. Using a member, one end of the plate-shaped glass member is previously integrated on one of the inner surfaces of the rear substrate and the front substrate, and thereafter, the indium alloy is placed at a predetermined position on the other inner surface of the rear substrate and the front substrate. And the other end of the sheet glass is joined to the other inner surfaces of the rear substrate and the front substrate.

Further, it is preferable that at least one of the baking and the bonding is performed at a temperature between the liquidus line and the solidus line of the indium alloy, and it is preferable that the bonding is performed in a vacuum.

According to the present invention, silver is added to indium,
There is provided an indium alloy for joining or vacuum sealing or joining and vacuum sealing obtained by adding at least one element selected from copper, gold, aluminum and antimony.

Elements such as silver, copper, gold, aluminum and antimony have the effect of increasing the melting point of indium when added to indium. When these elements are added alone or in combination in an appropriate amount to indium, a region in which two phases of a liquid phase and a solid phase coexist is generated when the element is kept at a high temperature in the subsequent heat treatment. In this sense, the heat treatment such as baking and bonding is desirably performed at a temperature between the liquidus line and the solidus line of the indium alloy.
In other words, at these heat treatment temperatures, the amounts of elements such as silver, copper, gold, aluminum, and antimony (the amount of these elements added) are set so that the indium alloy falls between the liquidus line and the solidus line on the binary or multiphase diagram. When adding these elements in combination, select the total amount).

The presence of the solid phase in such an indium alloy suppresses the surface contraction of the indium alloy due to surface tension, thereby ensuring sufficient wettability. Join
The features of the main component of the sealing member are fully utilized, and high bonding performance and vacuum sealing performance can be realized.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing a schematic configuration of a flat panel display using a cold cathode type electron-emitting device according to an embodiment of the present invention. This image display device displays an image by exciting and emitting light from a phosphor screen 3 with electron beams emitted from a large number of electron-emitting devices 2 in a vacuum envelope 1 formed in a plate shape as a whole. More specifically, it is configured as follows.

The vacuum envelope 1 is a glass container mainly composed of a glass back substrate 4 and a front substrate 5 which are arranged in a spaced apart and substantially parallel manner. Is provided with a plate-shaped side wall 6 made of glass at the periphery. The plate-like partition 6 is composed of the rear substrate 4 and the front substrate 5.
It is preferable that the back substrate 4 and the front substrate 5 have different thermal expansion coefficients when the rear substrate 4 and the front substrate 5 have different thermal expansion coefficients. It is desirable to be formed by a glass member having a coefficient. Further, between the rear substrate 4 and the front substrate 5, a number of spacers 7 for supporting the atmospheric pressure applied to the rear substrate 4 and the front substrate 5 are arranged.

The electron-emitting devices 2 are arranged in a matrix on the inner surface of the rear substrate 4 (the surface facing the front substrate 5). The electron-emitting device 2 is a known cold-cathode-type electron-emitting device. For example, the electron-emitting device 2 is continuous with both an insulating layer made of a SiO ₂ film and a gate electrode layer made of a Mo film laminated on a Si single crystal substrate. A large number of minute holes are formed in a matrix by etching, and a conical emitter made of, for example, Mo is formed in these holes. Further, the electron-emitting device 2 is connected to a driving circuit via a matrix wiring (not shown), and is driven by the driving circuit according to an image signal, so that an electron beam intensity-modulated according to the image signal is converted to a phosphor screen. Release towards 3.

The phosphor screen 3 is formed on the inner surface of the front substrate 5 (the surface facing the rear substrate 4), and emits light when excited by an electron beam emitted from the electron-emitting device 2. As a result, an image is displayed on the phosphor 3 by emitting light, and the user can see the displayed image through the front substrate 5. A metal back layer 8 is formed on the phosphor screen 3. When a full-color display device is configured as an image display device, the phosphor screen 3 is R
(Red), G (green), and B (blue) phosphor dots.

The inner surfaces of the rear substrate 4 and the front substrate 5 and the plate-like side wall 6 are joined by a joining and sealing material (indium alloy layer) 9 made of an indium alloy according to the present invention.
In addition, a vacuum seal of the vacuum envelope 1 is provided. The indium alloy serving as the bonding / sealing material 9 contains at least one element selected from the group consisting of silver, copper, gold, aluminum and antimony. By using such an indium alloy for the bonding and sealing material 9, the rear substrate 4 and the front substrate 5 made of glass are used.
Thus, the bonding performance between the plate-like side walls 6 also made of glass and the vacuum sealing performance are remarkably improved, and a highly reliable image display device can be realized.

The progress of the development of the above-mentioned indium alloy used as the bonding and sealing material 9 will be described below. The inventors have spent a lot of time elucidating the mechanism involved in joining glass and metal in order to solve the problems when using conventional metals such as indium and gallium as the joining and sealing materials for glass members. Came up with a new indium alloy. It is considered that the presence of oxygen is large for indium to wet or bond to glass. This causal relationship has been recognized in the experiments of the inventors. Therefore, the supply of oxygen is essential,
Normal wetting or bonding is provided by oxygen present on the glass surface or oxygen supplied from the atmosphere.

However, it has been found that when the specifications for the high-temperature heat treatment of the glass member to be joined become severe, such existing oxygen alone is not sufficient. In a situation where indium and glass are combined in a state where the supply of oxygen is insufficient, the force that separates indium from the glass surface due to the surface tension of the molten indium exceeds the bonding force between indium and the glass surface. As a result, after the heat treatment, hemispheres of indium corresponding to the surface tension remain on the surface of the glass member, and they cannot maintain a vacuum because they cannot form a continuous body.
In order to lower the surface tension of indium, a method of adding another element is conceivable. However, there is a problem that the melting point varies depending on the amount of addition, and a sufficient decrease in the surface tension cannot be expected. .

The inventors have found that such a problem can be solved if the indium alloy can exist partially as a solid without being completely melted at a predetermined temperature. That is, if an element having a function of increasing the melting point of indium by addition, such as silver, copper, gold, aluminum, or antimony, is added to indium, and the amount of addition is appropriately adjusted, a liquid melted at a predetermined temperature is obtained. It was found that a region in which two phases coexist, a phase and a solid phase, was obtained, and it was found that the presence of the solid phase could suppress surface contraction due to surface tension.

To confirm this effect, the inventors conducted the following experiment. Soda-lime glass dish placed on a hot plate heated to 300 ° C (1 m deep)
m) An ultrasonic soldering iron heated to about 300 ° C. by applying a ribbon of 0.1 mm thick 25% by weight silver-indium alloy to predetermined positions of a member and a flat lid member also made of soda lime glass. And welded.

Next, when the glass dish-like member and the plate-like lid member were heated at 300 ° C. for 1 hour under a vacuum of 3 × 10 ⁻⁶ Pa, the indium alloy was deposited on the glass surface of these members. Although melted, the melt of the indium alloy did not shrink due to surface tension and maintained its initial shape.

After the heat treatment, while maintaining the temperature of each member at 300 ° C., an appropriate amount of a 1 mm-high spacer is disposed between the glass dish-shaped member and the plate-shaped lid member. The members were joined. A vacuum leak test of a space formed between the glass dish-shaped member and the plate-shaped lid member was performed at room temperature. As a result, it was 1 × 10 ⁻⁹ atm · cc / sec or less. It was confirmed that.

When a glass member is bonded by using an indium alloy obtained by adding silver to indium as a bonding and sealing material, excellent bonding performance and vacuum sealing performance can be obtained even after high-temperature heat treatment. Therefore, the reliability of the image display device is improved by using the bonding and sealing material as the bonding and sealing material 9 of the vacuum envelope 1 in the image display device shown in FIG.

Next, among the manufacturing steps of the image display device according to the present embodiment, steps particularly related to the present invention will be described. A back substrate 4 having an electron-emitting device 2 formed on an inner surface thereof;
A front substrate 5 having a phosphor screen 3 and a metal back layer 8 formed on the inner surface thereof is opposed to each other with a plate-shaped side wall 6 and a spacer 7 interposed therebetween.
Constitutes the vacuum envelope 1. In this case, the rear substrate 4 and the front substrate 5 and the plate-like side wall 6 are joined together by a joining and sealing material 9 made of an indium alloy, and a vacuum seal is performed.

In an actual process, the rear substrate 4 and the front substrate 5 are sufficiently separated in a vacuum device (not shown).
These rear substrate 4 and front substrate 5 are, for example, 300 to 4
While baking at a temperature of about 00 ° C., the entire inside of the vacuum device is evacuated until a high vacuum is obtained. When a predetermined degree of vacuum is reached, the rear substrate 4 and the front substrate 5 are opposed to each other via the plate-shaped side wall 6, and the bonding and sealing material 9 is attached to the rear substrate 4.
And placed at a position facing the plate-like side wall 6 on the inner surface of the front substrate 5 and heated and melted to a temperature of, for example, 160 ° C. or more, so that the back substrate 4 and the front substrate 5 and the plate-like side wall 6 are joined and vacuum sealed.

The bonding and sealing material 9 has sufficient bonding strength for bonding with the rear substrate 4, the front substrate 5, and the plate-like partition 6, and also has the bonding and sealing material 9 even at high temperature and high vacuum. And the wettability to the rear substrate 4 and the front substrate 5 is maintained even at a high temperature, and the accumulation of the bonding and sealing material 9 and the flowing of the bonding and sealing material 9 from a predetermined position It must not protrude or spill.

Here, if the joining and sealing material 9 is formed of an indium alloy obtained by adding silver to indium as described above, the above-mentioned joining and sealing material 9 can be obtained from the above experimental results.
To meet the demands for Therefore, by using such a joining and sealing material 9, the image display having a high reliability can be efficiently achieved with a simple structure and a simple manufacturing process, and the joining and the vacuum sealing performance of the vacuum envelope 1 are excellent. The device can be manufactured, and its industrial effect is extremely high.

As the element to be added to indium, the melting point is increased by adding to indium,
In addition to silver, metal elements such as copper, gold, aluminum, and antimony may be used as long as they realize an indium alloy that realizes a solid-liquid two-phase that exhibits an effect of maintaining a shape during heat treatment at a high temperature of 0 ° C. It is valid. Needless to say, two or more elements selected from the group consisting of silver, copper, gold, aluminum, and antimony may be added to indium in combination. Further, the amounts of these elements to be added are determined depending on the heat treatment step to be performed, and are selected so that the liquidus line of the indium alloy has a composition higher than the heat treatment temperature. In other words, it is desirable that the heat treatment at the time of baking or bonding be performed at a temperature between the liquidus line and the solidus line of the indium alloy.

The present invention is not limited to the above embodiment, but can be implemented with various modifications. For example, in the image display device of the above embodiment, as described with reference to FIG. 1, the joining / sealing between the inner surface of the rear substrate 4 and the plate-like partition 6 and the inner surface of the front substrate 5 and the plate-like side wall 6 are made of an indium alloy. Although the joining is performed by the material 9, the present invention is not limited to this.

For example, as shown in FIG. 2, the rear substrate 4 and the plate-like side wall 6 are integrally formed in advance by integral molding or joining, and the inner surface of the front substrate 5 and the plate-like side wall 6 are joined and sealed with a sealing material 9. It may be joined, or conversely, FIG.
As shown in (1), the front substrate 5 and the plate-shaped side wall 6 may be integrally formed in advance by integral molding or bonding, and the inner surface of the rear substrate 4 and the plate-shaped side wall 6 may be bonded by a bonding and sealing material 9. .

In the above embodiment, the case where the indium alloy according to the present invention is used as the joining and sealing member 9 has been described. However, it is also possible to use the indium alloy as a member only for joining or only for vacuum sealing. further,
In the above embodiment, the partition 6 is provided between the rear substrate 4 and the front substrate 5.
However, the two substrates may be directly bonded and vacuum sealed with an indium alloy without such a partition.

The use of the indium alloy is not limited to the image display device using the above-described cold cathode type electron-emitting device, but may be applied between glass members or between a glass member and another member, or between these members. Widely applicable to vacuum seals. The present invention can also be implemented as a glass part using the above-described indium alloy as a joining member, a vacuum sealing member, or a joining and sealing member.

As described above, according to the present invention, an indium alloy in which at least one element selected from the group consisting of silver, copper, gold, aluminum and antimony is added to indium, and silver, copper, gold, aluminum and antimony are added to indium. Indium alloy for joining or vacuum sealing or joining and vacuum sealing to which at least one element selected from the group is added, and glass parts joined, vacuum-sealed or joined and vacuum-sealed with the indium alloy. Can also be provided.

[0038]

As described above, according to the present invention, it is possible to join and vacuum seal a glass vacuum envelope which requires a high vacuum and requires a high-temperature heat treatment step during manufacturing. Thus, it is possible to provide an image display device suitable as an FPD panel using a cold cathode type electron-emitting device, which has been difficult to realize.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a schematic configuration of an image display device according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a schematic configuration of an image display device according to another embodiment of the present invention.

FIG. 3 is a sectional view showing a schematic configuration of an image display device according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Vacuum envelope 2 ... Electron emission element 3 ... Phosphor screen 4 ... Back substrate 5 ... Front substrate 6 ... Side wall 7 ... Spacer 8 ... Metal back layer 9 ... Joining and sealing material

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takashi Nishimura 1-9-2 Hara-cho, Fukaya-shi, Saitama Pref. Inside the Toshiba Fukaya Plant (72) Inventor Akiyoshi Yamada 1-9-1-2 Hara-cho, Fukaya-shi, Saitama No. F-term in Toshiba Fukaya Plant (reference) 5C012 AA05 BC03 5C032 AA01 BB18 5C036 EE17 EF01 EF06 EF09 EG06 EH11

Claims (6)

[Claims] 1. A vacuum envelope comprising a rear substrate and a front substrate made of glass and arranged substantially in parallel at a distance from each other, a plurality of electron-emitting devices arranged on an inner surface of the rear substrate, and the front surface A phosphor screen formed on an inner surface of the substrate and excited by an electron beam emitted from the electron-emitting device to emit light, wherein the rear substrate and the front substrate are made of silver, copper, gold, aluminum and antimony. An image display device joined via an indium alloy layer containing at least one element selected from the group consisting of: 2. The vacuum envelope further includes a partition interposed between the rear substrate and the front substrate, wherein at least one of the rear substrate and the front substrate and the partition are formed of the indium alloy layer. The image display device according to claim 1, wherein the image display device is joined via a link. 3. A vacuum envelope comprising a rear substrate and a front substrate made of glass and arranged substantially in parallel at a distance from each other, and a plurality of electron-emitting devices arranged and formed on an inner surface of the rear substrate.
A phosphor screen formed on the inner surface of the front substrate and excited by an electron beam emitted from the electron-emitting device to emit light, wherein at least one of the rear substrate and the front substrate At a predetermined position on the inner surface, an indium alloy obtained by adding at least one element selected from the group of silver, copper, gold, aluminum and antimony to indium is placed, and the indium alloy is welded by melting at a predetermined temperature. And then bonding the back substrate and the back substrate with the indium alloy through a baking process in a vacuum. 4. The vacuum envelope further includes a partition interposed between the back substrate and the front substrate, and the partition is bonded to at least one of the back substrate and the front substrate with the indium alloy. 4. The method for manufacturing an image display device according to claim 3, wherein: 5. A plate glass member having substantially the same thermal expansion characteristics as at least one of the rear substrate and the front substrate is used as the partition, and the plate glass member is previously placed on one inner surface of the rear substrate and the front substrate. After that, the indium alloy is placed at a predetermined position on the other inner surface of the back substrate and the front substrate, and the sheet glass is bonded to the other inner surface of the back substrate and the front substrate. The method for manufacturing an image display device according to claim 4, wherein: 6. The method of claim 3, wherein at least one of the baking and the bonding is performed at a temperature between a liquidus line and a solidus line of the indium alloy. Manufacturing method of an image display device.