JPH11183884A - Display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lessen the leakage of the mercury vapor packed in a display device utilizing plasma discharge. SOLUTION: A plasma cell 2 is divided to a junction region where a sealing material 11 is disposed, a hermetically closed internal region which exists on the inner side thereof and an opened external region which exists on the outer side of the junction region. External electrodes 20 extended from the junction region to the external region and internal electrodes extended from the junction region to the internal region are formed on a substrate 8 of one side. The internal electrodes consist of a series connection of discharge electrodes 9 and pad electrodes 19. The internal region is filled with ionizable gas which generates an electric discharge according to the voltage impressed on the discharge electrodes 9 via the external electrodes 20 and the mercury vapor for preventing the deterioration of the discharge electrodes 9 by the electric discharge. Insulating films 21 covering the ends of the discharge electrodes 9 and the pad electrodes 19 are formed from part of the internal region to part of the junction region in order to prevent the abnormal electric discharge. The outermost end edges 21T of the insulating films 21 advancing into the junction region from the internal region retreat toward the internal region side from the outermost end edges 19T at the ends of the pad electrodes 19 to prevent the contact of the mercury vapor with the external electrodes 20 through the insulating films 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a display device utilizing plasma discharge. Specifically, the present invention relates to a sealing structure of a plasma cell included in a display device. More specifically, the present invention relates to a technique for preventing leakage of mercury vapor introduced into a plasma cell in order to improve reliability.

[0002]

2. Description of the Related Art A display device using a plasma discharge is of a flat panel type and has attracted attention as a large display. PDP using plasma discharge for direct display
(Plasma display panel) and PALC (Plasma Addressed Liquid Crystal Display) using a plasma cell for addressing a liquid crystal cell and the like have been actively developed. A plasma addressed liquid crystal display device is disclosed in, for example,
No. 31, the outline of which is shown in FIG.
This display device has a flat panel structure including a display cell 1, a plasma cell 2, and a common intermediate substrate 3 interposed between the display cell 1 and the plasma cell 2. The plasma cell 2 is composed of a lower substrate 8 bonded to the intermediate substrate 3, and an ionizable gas is sealed in a gap between the two. On the inner surface of the lower substrate 8, a striped discharge electrode 9 is formed. Since the discharge electrode 9 can be printed and baked on the flat substrate 8 by a screen printing method or the like, it is excellent in productivity and workability and can be miniaturized. A partition 10 is provided on the discharge electrode 9.
Are formed, and the gap filled with the ionizable gas is divided to form the discharge channel 12. This partition 1
0 can also be printed and baked by a screen printing method or the like, and the top portion is in contact with the lower surface side of the intermediate substrate 3. The striped discharge electrodes 9 function alternately as anodes A and cathodes K, and generate a plasma discharge between them. In addition,
The intermediate substrate 3 and the lower substrate 8 are joined to each other by a sealing material 11 such as a glass frit.

On the other hand, the display cell 1 is constituted by using a transparent upper substrate 4. The upper substrate 4 is adhered to the intermediate substrate 3 via a predetermined gap with an adhesive 6, and the gap is filled with an electro-optical material 7 such as a liquid crystal. The signal electrode 5 is formed on the inner surface of the upper substrate 4. This signal electrode 5 is orthogonal to the striped discharge channel 12. Pixels in a matrix are defined at intersections between the signal electrodes 5 and the discharge channels 12.

In the plasma addressed display device having such a configuration, a row-shaped discharge channel 1 in which a plasma discharge is performed is provided.
2 is switched in a line-sequential manner, and display driving is performed by applying an image signal to the column signal electrodes 5 on the display cell 1 side in synchronization with the scanning. When a plasma discharge is generated in the discharge channel 12, the inside becomes almost uniformly at the anode potential, and pixel selection for each row is performed. That is, the discharge channel 12 functions as a sampling switch. When an image signal is applied to each pixel in a state where the plasma sampling switch is turned on, sampling is performed and lighting or extinguishing of the pixel can be controlled. Even after the plasma sampling switch is turned off, the image signal is held in the pixel as it is.

[0005]

The discharge channel 12 of the plasma cell 2 is filled with mercury vapor in addition to an ionizable gas. The mercury vapor is used to suppress the sputtering of the discharge electrode 9 due to the plasma discharge and to secure the life of the plasma cell 2. However, the sealing structure of the conventional plasma cell 2 is not always perfect, and when a heat treatment or the like is performed in the manufacturing stage, the mercury vapor enclosed therein reacts with an external electrode for extracting a terminal to form an alloy (amalgam). There was a problem to do. When amalgamated, the amount of mercury vapor inside the cell becomes insufficient. Further, the volume of the external electrode changes due to amalgamation, and in the worst case, disconnection or the like occurs. An object of the present invention is to reduce the amalgamation described above.

[0006]

The following means have been taken in order to solve the above-mentioned problems of the prior art. That is, the plasma addressed display device according to the present invention has a flat panel structure including a display cell and a plasma cell which are overlapped with each other via an intermediate substrate. The display cell has an upper substrate joined to the intermediate substrate via a predetermined gap, an electro-optical material held in the gap, and a row of signal electrodes formed on the upper substrate. The plasma cell is configured using a lower substrate bonded to the intermediate substrate via a sealing material, and includes a bonding region in which the sealing material is disposed, and a sealed internal region located inside the bonding region. And an open outer region located outside the joining region. A row-shaped external electrode extending from the bonding region to the external region and a row-shaped internal electrode extending from the bonding region to the internal region are formed on the lower substrate, and the internal electrode is connected to the external electrode in the bonding region. Electrically connected. The internal region is filled with an ionizable gas that generates a discharge according to a voltage applied to the internal electrode via the external electrode, and mercury vapor that prevents deterioration of the internal electrode due to the discharge. Further, in order to prevent abnormal discharge, an insulating film covering an end of the internal electrode is formed from a part of the internal region to a part of the bonding region. As a characteristic feature, the outermost edge of the insulating film that has entered the bonding region from the inner region is receded from the outermost edge of the end of the internal electrode toward the inner region, and mercury vapor is removed from the insulating film. Through to prevent contact with the external electrode.

The present invention can be applied to ordinary plasma display devices in addition to the above-described plasma address display device. The plasma display device basically has a cell structure including a pair of substrates joined to each other via a sealing material. The cell structure is divided into a joint area in which the sealing material is disposed, a sealed internal area located inside the joint area, and an open external area located outside the joint area. On one side of the substrate is an external electrode extending from the bonding area to the external area,
An internal electrode extending from the bonding region to the internal region is formed, and the internal electrode is electrically connected to the external electrode in the bonding region. The internal region is filled with an ionizable gas that generates a discharge according to a voltage applied to the internal electrode via the external electrode, and mercury vapor that prevents deterioration of the internal electrode due to the discharge. Further, in order to prevent abnormal discharge, an insulating film covering an end of the internal electrode is formed from a part of the internal region to a part of the bonding region. As a feature,
The outermost edge of the insulating film that has entered the bonding region from the internal region is receded from the outermost edge of the end of the internal electrode toward the internal region, and mercury vapor is transferred to the external electrode through the side insulating film. Make it difficult to contact. Preferably, the internal electrode comprises a discharge electrode having a relatively coarse composition suitable for discharge and a pad electrode having a relatively dense composition so that mercury vapor is hardly permeated. The discharge electrode is connected to the external electrode via the pad electrode. The pad electrode is made of nickel or chromium. The inner electrode is made of nickel which does not easily react with mercury vapor, and the outer electrode is made of gold, silver or copper which easily reacts with mercury vapor. Further, the insulating film is made of a glass film.

In a plasma cell, an internal electrode and an external electrode are electrically connected to each other in a bonding region. An insulating film such as a glass film is also formed to prevent abnormal discharge at the end of the internal electrode, and a part of the insulating film also exists in the bonding region. An insulating film made of a glass film or the like transmits mercury vapor relatively easily. On the other hand, the external electrodes are made of gold, silver, copper, or the like in order to secure sealing properties in the bonding region. These metals have the property of reacting with mercury vapor to form amalgam. The present invention employs a structure in which the mercury vapor hardly comes into direct contact with the external electrode by retracting the insulating film serving as a passage for the mercury vapor from the internal electrode. With such a structure, amalgamation of the external electrode is reduced, and loss of mercury vapor filled in the discharge channel can be significantly suppressed.

[0009]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic view showing a display device according to the present invention, and shows a plasma-addressed display device. To facilitate understanding, portions corresponding to those of the plasma address display device shown in FIG. 4 are denoted by corresponding reference numerals. However, it goes without saying that the present invention can be applied not only to a plasma address type display device but also to a normal plasma display device. FIG. 1A is a schematic partial plan view of the present plasma addressed display device, and FIG. 1B shows a schematic sectional structure of a portion corresponding to FIG. These partial plan views (A) and partial cross-sectional views (B) focus on the vicinity of the bonding region of the plasma addressed display device.

As shown in FIGS. 1A and 1B, the present display device has a flat panel structure including a display cell 1 and a plasma cell 2 which are overlapped with each other via a sealing material 11 made of glass frit or the like. Have. The display cell 1 includes an upper substrate 4 joined to the intermediate substrate 3 with a predetermined gap, an electro-optical material 7 such as liquid crystal held in the gap, and a row of signal electrodes 5 formed on the upper substrate 4. Having.
As shown in (B), the column direction of the signal electrodes 5 is set perpendicular to the paper surface. Note that the upper substrate 4 and the intermediate substrate 3 are joined to each other by an adhesive 6.

On the other hand, the plasma cell 2 is configured using a lower substrate 8 bonded to the intermediate substrate 3 via a sealing material 11 such as a glass frit. The plasma cell 2 is divided into a joining region in which the sealing material 11 is arranged, a sealed inner region located inside the joining region, and an open outer region located outside the joining region. Row-shaped external electrodes 20 extending from the bonding region to the external region are provided on the lower substrate 8.
And a row-shaped internal electrode extending from the joint region to the internal region are formed, and the internal electrode is electrically connected to the external electrode in the joint region. As shown in (B), the row direction is parallel to the paper surface. In this embodiment, the internal electrode has a discharge electrode 9 having a relatively coarse composition suitable for discharge and a pad electrode 19 having a relatively dense composition so that mercury vapor is hardly permeated.
Consists of The discharge electrode 9 is connected to an external electrode 20 via a pad electrode 19.

The inner region includes an ionizable gas that generates a discharge in accordance with a voltage applied to the discharge electrode 9 via an external electrode (terminal electrode) 20, and a mercury vapor that prevents deterioration of the discharge electrode 9 due to plasma discharge. And are filled with. The discharge electrodes 9 are formed in a stripe shape along the row direction, and function alternately as anodes A and cathodes K. A partition 10 is formed on each anode A. The partition walls 10 are formed in rows over the entire internal region. Correspondingly, the partition 10 is also formed on the external electrode 20. These partitions 10 function as spacers between the intermediate substrate 3 and the lower substrate 8. The partition 10 is partially removed from the bonding area. A sealing material 11 such as a glass frit is provided on the removed portion.
Is supplied.

In order to prevent abnormal discharge, an insulating film 21 covering the ends of the discharge electrode 9 and the pad electrode 19 is formed from a part of the internal region to a part of the bonding region. Note that the external electrode 20 is also covered with the insulating film 21. Plasma discharge occurs stably at the center of the internal region, but becomes unstable at the periphery of the internal region. Since such abnormal discharge impairs the image quality of the display device, in the present embodiment, the insulating film 21 is formed so as to cover the end of the internal electrode. As the insulating film 21, a glass film is typically used. As a characteristic matter, the outermost edge 21T of the insulating film 21 that has entered the bonding region from the internal region.
Are receded from the outermost edge 19T of the end of the pad electrode 19 toward the internal region. With such a configuration, the mercury vapor is hardly brought into contact with the external electrode 20 through the insulating film 21. As shown in FIG. 3B, the pad electrode 19 has a structure between the insulating film 21 and the external electrode 20. As described above, the discharge electrode 9 located mainly in the inner region has a relatively coarse composition suitable for plasma discharge. Pad electrode 19 mainly located in the bonding region
Conversely, has a relatively dense composition so that mercury vapor is difficult to permeate. The discharge electrode 9 and the pad electrode 19 constituting the internal electrode generally use nickel which hardly reacts with mercury vapor. On the other hand, gold, silver, or copper is mainly used for the external electrode 20 located in the external region in order to enhance the sealing property in the bonding region. These metal elements easily react with mercury vapor to form amalgam. Note that chromium (Cr) may be used as the pad electrode in addition to nickel (Ni).
Chromium can maintain conductivity with the discharge electrode 9 and the external electrode 20 without any problem even when printing and baking. In addition, there is no need to worry about oxidation to become an insulator during printing and firing.

In order to reduce the problem of amalgamation of the external electrode 20, according to the present invention, as shown in FIG. The portion recedes from the outermost edge 19T of the portion toward the inner region side, so that mercury vapor hardly contacts the external electrode 20 through the insulating film 21. With such a structure, the path through which the mercury vapor reaches the portion where the external electrode (terminal electrode) 20 overlaps the pad electrode 19 is narrowed by the retreat of the outermost edge 21T of the protective film 21. Therefore, the amalgamation of the external electrode 20 is reduced, and the loss of the mercury vapor filled in the discharge channel is suppressed.

FIG. 2 shows a reference example of the plasma addressed display device, in which parts corresponding to those of the embodiment of the present invention shown in FIG. I have to. In this reference example, since the outermost edge 21T of the insulating film 21 has advanced to the position of the outermost edge 19T of the pad electrode 19, the mercury vapor filled in the internal region penetrates the insulating film 21 and easily. Reaches the end of the external electrode 20 and amalgamation occurs. In the plasma cell 2,
When nickel is used as a constituent material of the discharge electrode 9, mercury vapor is diffused in the inner region of the plasma cell 2 as described above. The purpose of this is to suppress the sputtering accompanying the plasma discharge of the discharge electrode 9 made of nickel and to secure the life of the plasma cell 2. Therefore, this mercury vapor forms amalgam with the external electrode 20 on the external region side,
Loss of mercury vapor in the discharge channel poses a reliability problem. As described above, the external electrode 20 is made of a metal material such as gold or silver, which easily forms amalgam.

The passage through which the mercury vapor leaks from the internal region to the external region includes an internal electrode formed of a discharge electrode 9 and a pad electrode 19 connected in series, and an insulating film 21 formed thereon.
You could think so. Of these, the internal electrodes are usually gold,
A conductive paste material made of nickel or the like other than silver or copper is used. For this reason, it is difficult to completely block mercury vapor, and the film quality is somewhat rough. However, the permeation of mercury vapor can be considerably prevented by keeping the pad electrode 19 in a relatively dense state while keeping the internal discharge electrode 9 of the internal electrode in a relatively rough state. In contrast, the insulating film 21
Is made of glass or the like and is originally provided to prevent abnormal discharge at the end of the discharge electrode 9. There is no problem if the insulating film 21 has a dense film quality capable of completely blocking mercury vapor. However, the plasma cell 2
In this case, there is a restriction in physical properties such as a lower substrate 8 and a coefficient of thermal expansion, and a glass coating is often used as the insulating film 21. Examination has revealed that the glass coating has a composition to which mercury vapor can permeate to some extent. The insulating film 21 is more dominant as a passage for mercury vapor than the internal electrode. Therefore, in the structure of the reference example as shown in FIG. 2, mercury vapor can relatively easily reach the vicinity of the portion of the external electrode 20 overlapping the pad electrode 19. By the way, the thickness of the pad electrode 19 is 5 to 2
It is set to about 0 μm, and the thickness of the insulating film 21 is 20 to 45 μm.
μm, and the thickness of the external electrode 20 is 5 to 15 μm.
m, and the thickness of the discharge electrode 9 is 30 to 55 μm.
Typically, it is set to a degree.

FIG. 3 is a schematic partial cross-sectional view showing another embodiment of the display device according to the present invention, and portions corresponding to those of the previous embodiment shown in FIG. And make it easy to understand. In the present embodiment, the discharge electrode 9 and the external electrode 20 are electrically connected directly in the joint region without the intermediate pad electrode. In other words, in this embodiment, the internal electrodes are constituted only by the discharge electrodes 9. Also in the present embodiment, the insulating film 2 that has entered the bonding region from the internal region
1 is the outermost edge 9T of the end of the discharge electrode 9.
The structure adopts a structure in which the mercury vapor recedes further toward the inner region side and is hard to contact the external electrode 20 through the insulating film 21. With such a configuration, amalgamation of the external electrode (terminal electrode) 20 is reduced, and loss of mercury vapor diffused in the discharge channel can be suppressed.

[0018]

As described above, according to the present invention,
The loss of the mercury vapor filled in the internal region of the plasma cell can be suppressed, and the life of the plasma cell can be improved. If the mercury vapor leaks to the outside, the plasma of the discharge electrode (particularly the cathode) is sputtered, and the metal particles adhere to the lower substrate or the intermediate substrate made of glass or the like, so that the transmittance is reduced.

[Brief description of the drawings]

FIG. 1 is a partial plan view and a partial sectional view showing an embodiment of a display device according to the present invention.

FIG. 2 is a partial sectional view showing a reference example of the display device.

FIG. 3 is a partial sectional view showing another embodiment of the display device according to the present invention.

FIG. 4 is a cross-sectional view illustrating an example of a conventional display device using plasma discharge.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Display cell, 2 ... Plasma cell, 3 ... Intermediate substrate, 4 ... Upper substrate, 5 ... Signal electrode, 7 ...
・ Electro-optical material, 8 ・ ・ ・ Lower substrate, 9 ・ ・ ・ Discharge electrode, 10 ・ ・ ・ Partition, 11 ・ ・ ・ Sealing material, 12 ・ ・ ・
Discharge channel, 19: pad electrode, 19T: outermost edge of pad electrode, 20: external electrode (terminal electrode), 21: insulating film, 21T: outermost edge of insulating film edge

Claims (10)

[Claims] 1. A flat panel structure comprising a display cell and a plasma cell which are overlapped with each other via an intermediate substrate, wherein the display cell is connected to the intermediate substrate via a predetermined gap, and And an array of signal electrodes formed on the upper substrate, and the plasma cell is configured using a lower substrate bonded to the intermediate substrate via a sealing material. A sealing region in which the sealing material is disposed, a sealed inner region located inside the joining region, and an open outer region located outside the joining region. A row-shaped external electrode extending from the bonding region to the external region and a row-shaped internal electrode extending from the bonding region to the internal region are formed on the substrate, and the internal electrode is electrically connected to the external electrode in the bonding region. Connected, the inner area is an external electrode Filled with an ionizable gas that generates a discharge according to the voltage applied to the internal electrode through the electrode and mercury vapor that prevents the internal electrode from deteriorating due to the discharge, and a part of the internal area to prevent abnormal discharge An insulating film covering the end of the internal electrode is formed from the inner region to a part of the bonding region, and the outermost edge of the insulating film that has entered the bonding region from the inner region is the outermost end of the end of the internal electrode. A display device, which is receded from the edge toward the inner region, so that mercury vapor is hardly brought into contact with an external electrode through the insulating film. 2. The internal electrode comprises a discharge electrode having a relatively coarse composition suitable for discharging and a pad electrode having a relatively dense composition so that mercury vapor is hardly permeated. The display device according to claim 1, wherein the display device is connected to the external electrode via a pad electrode. 3. The display device according to claim 2, wherein said pad electrode is made of nickel or chromium. 4. The display device according to claim 1, wherein said internal electrode is made of nickel which does not easily react with mercury vapor, and said external electrode is made of gold, silver or copper which easily reacts with mercury vapor. 5. The display device according to claim 1, wherein said insulating film is made of a glass film. 6. A cell structure comprising a pair of substrates joined to each other via a seal material, wherein the cell structure is a joint region where the seal material is arranged, and a sealed structure located inside the joint region. The substrate is separated into an inner region and an open outer region located outside the bonding region. One of the substrates has an external electrode extending from the bonding region to the outer region, and an external electrode extending from the bonding region to the inner region. Is formed, and the internal electrode is electrically connected to the external electrode in the joint region. The internal region is ionized to generate a discharge in accordance with a voltage applied to the internal electrode via the external electrode. An insulating film that is filled with a possible gas and mercury vapor that prevents deterioration of the internal electrode due to discharge, and covers the end of the internal electrode from a part of the internal area to a part of the bonding area to prevent abnormal discharge Are formed, and the internal territory is The outermost edge of the insulating film that has entered the bonding region from the inner electrode recedes toward the inner region from the outermost edge of the end of the internal electrode, and mercury vapor contacts the external electrode through the insulating film. A display device characterized in that it is made difficult. 7. The internal electrode comprises a discharge electrode having a relatively rough composition suitable for discharge and a pad electrode having a relatively dense composition so that mercury vapor is hardly permeated. 7. The display device according to claim 6, wherein the display device is connected to the external electrode via a pad electrode. 8. The display device according to claim 7, wherein said pad electrode is made of nickel or chromium. 9. The display device according to claim 6, wherein said internal electrode is made of nickel which does not easily react with mercury vapor, and said external electrode is made of gold, silver or copper which easily reacts with mercury vapor. 10. The display device according to claim 6, wherein said insulating film is made of a glass film.