JPH10161549A - Picture display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of the discontinuity caused by the resistance abnormality of the electrodes that are reacted to diffusion and the occurrence of the abnormal electric discharge caused by the damage to a cover glass by employing the crystalline glass as the cover glass layer which covers the joint sections of electric discharge and terminal electrodes in the region between a partition and a frit seal. SOLUTION: A terminal electrode 14 is formed as an external leader line electrode to connect electric discharge electrodes (an anode electrode and a cathode electrode) 9 to an external driving circuit. The electrode 14 is directly connected to the electrodes 9 in a plasma cell. A partition 10, which is formed on the electrodes 9, should be formed slightly separated from a frit seal 11 and a cover glass 17 is formed in this region to cover these electrodes. Note that a crystalline glass is used as the glass 17. A stringent control for the calcination temperature is required for the crystalline glass. However, the flowability is small and diffusion reaction with the electrodes 9 and 14 is hard to be generated. Thus, the occurrence of abnormal resistive values at electrode joint sections and discontinuity are prevented.

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 (so-called plasma address display device) for displaying an image by driving an electro-optical material layer using plasma.

[0002]

2. Description of the Related Art For example, as a method for increasing the resolution and contrast of a liquid crystal display, a method of providing an active element such as a transistor for each display pixel and driving the same, that is, a so-called active matrix address method is known. is there.

However, in this case, since it is necessary to provide a large number of semiconductor elements such as thin film transistors,
In particular, when the area of the display is increased, there is a concern about the yield problem, and there is a problem that the cost is inevitably increased.

Therefore, as a means for solving this problem,
A method has been proposed in which discharge plasma is used as an active element instead of a semiconductor element such as a MOS transistor or a thin film transistor.

[0005] An image display device (hereinafter, referred to as a plasma address display device) that drives a liquid crystal using the discharge plasma includes a liquid crystal layer that is an electro-optic material layer and a plasma cell that discharges the plasma. , Adjacent to each other via a dielectric thin plate made of glass or the like.

In the above-mentioned plasma addressed display device, the plasma cell is divided into a line-shaped plasma chamber by a partition, and the plasma chamber in which the plasma discharge is performed is sequentially switched and scanned, and the transparent electrode facing the liquid crystal layer is interposed. The liquid crystal layer is driven by applying a signal voltage in synchronization with this.

[0007]

By the way, in the above-mentioned plasma addressed display device, the discharge electrode is formed by printing and firing a conductive paste so that a plurality of electrode lines are arranged in parallel at equal intervals. On the other hand, the partition partitioning the plasma chamber is formed by printing and firing an insulating paste on the discharge electrode.

[0008] However, in order to perform the evacuation and the introduction of the discharge gas in each plasma chamber at once,
A small space is formed between the plasma chamber and the frit seal so that gas can flow between the plasma chambers through this space.

Here, the discharge electrode in the region between the partition and the frit seal is usually covered with a cover glass layer. The main purpose is to prevent abnormal discharge from occurring due to the discharge electrodes in this area.

The area covered by the cover glass layer usually corresponds to a discharge electrode and an electrode joint for connecting the discharge electrode to an external circuit, and the cover glass layer is laminated on the electrode joint.

As a material of such a cover glass layer, an amorphous glass is used because it is easy to flow by baking and is easily airtightly coated.

However, when amorphous glass is used as the cover glass, the following disadvantages occur.

That is, since the amorphous glass easily flows, it interdiffuses with the terminal electrode and the discharge electrode, and melts and mixes with the glass contained in these electrode materials to cause an oxidation-reduction reaction. When such an oxidation-reduction reaction occurs, foaming occurs at the interface between the cover glass and the terminal electrode, or at the interface between the cover glass and the discharge electrode, and the cover glass is damaged, thereby impairing the function of preventing the above-described abnormal discharge. It is.

Further, when the amorphous glass diffuses into the joint between the terminal electrode and the discharge electrode, the reaction between the terminal electrode material and the discharge electrode material is promoted, which may cause poor sintering of the joint. Poor sintering results in an abnormal resistance value, which may cause a problem in that the joints of the electrodes generate heat during electric discharge and are disconnected.

Accordingly, the present invention has been proposed in view of such a conventional situation, and has as its object to reduce the diffusion reaction between a cover glass layer and an electrode and improve the reliability of a plasma addressed display device. I do.

[0016]

According to the present invention, in order to achieve the above-mentioned object, a predetermined gap is formed on a first substrate having a plurality of substantially parallel discharge electrodes formed on one main surface. A second substrate in which a thin dielectric plate is disposed, a periphery thereof is sealed with a seal portion to form a plasma cell, and an electrode substantially orthogonal to the discharge electrode is formed on an opposite surface on the thin dielectric plate. In the image display device is superimposed via an electro-optic material layer, on the discharge electrode, a partition partitioning the plasma cell is formed apart from the seal portion, at least in the region between the partition and the seal portion A cover glass layer is formed to cover each of the electrodes, and the cover glass layer is made of crystalline glass.

As described above, when crystalline glass is used for the cover glass layer instead of amorphous glass, the crystalline glass has low fluidity, so that a diffusion reaction with the electrode hardly occurs, and the cover glass is damaged. The occurrence of abnormal discharge and disconnection due to abnormal resistance of the electrodes are prevented.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a plasma addressed display device of this embodiment.
And as shown in FIG. 2, it has a so-called flat panel structure in which an electro-optical display cell 1, a plasma cell 2, and a dielectric sheet 3 interposed therebetween are laminated.

The dielectric sheet 3 is made of thin glass or the like and functions as a capacitor by itself. Therefore, in order to sufficiently secure the electrical coupling between the electro-optical display cell 1 and the plasma cell 2 and to suppress the two-dimensional spread of electric charges, it is preferable that the dielectric sheet 3 is as thin as possible. Specifically, for example, a thin glass plate having a thickness of about 50 μm is used.

The electro-optical display cell 1 is formed by bonding a glass substrate (upper substrate) 4 on the dielectric sheet 3 with a predetermined gap maintained by a spacer 6.

A gap between the dielectric sheet 3 and the upper substrate 4 is filled with a liquid crystal material as an electro-optical material, and a liquid crystal layer 7 is formed. In addition, as the electro-optic material, a material other than the liquid crystal can be used.

Here, the dimension of the gap between the upper substrate 4 and the dielectric sheet 3 is, for example, 4 to 10 μm, and is kept substantially uniform over the entire display surface.

On the surface of the upper substrate 4 facing the dielectric sheet 3, a plurality of data electrodes 5 made of a transparent conductive material and extending in the row direction, for example, are arranged in parallel in the column direction while maintaining a predetermined interval. Are arranged.

On the other hand, the plasma cell 2 is composed of the dielectric sheet 3 and a glass substrate (lower substrate) 8 disposed below the dielectric sheet 3.

On a surface of the lower substrate 8 facing the dielectric sheet 3, a plurality of anode electrodes 9A and cathode electrodes 9K extending in a direction orthogonal to the data electrodes 5, that is, in a column direction.
Are alternately arranged in parallel while maintaining a predetermined interval, and constitute a discharge electrode group.

The center of the upper surface of each of the anode electrode 9A and the cathode electrode 9K is extended along the electrodes.
A partition 10 having a predetermined width is formed. And each partition 1
The top of 0 is in contact with the lower surface of the dielectric sheet 3, and the gap between the lower substrate 8 and the dielectric sheet 3 is kept substantially constant.

Further, the dielectric sheet 3 has a frit seal 11 using a low melting point glass or the like at the outer peripheral edge.
Accordingly, the plasma cell 2 is hermetically bonded to the lower substrate 8, and the plasma cell 2 is configured as a closed space.
An ionizable gas such as helium, neon, argon, or a mixture thereof is sealed in the closed space.

In the above-described plasma addressed display device, a plurality of discharge channels (spaces) 12 separated by each partition 10 are formed in parallel in the row direction in the gap between the lower substrate 8 and the dielectric sheet 3. This discharge channel 12 is orthogonal to the data electrode 5.

Accordingly, each data electrode 5 is a unit of column drive, and each discharge channel 12 is a unit of row drive. As shown in FIG.

When a driving voltage is applied between the anode electrode 9A and the cathode electrode 9K corresponding to a predetermined discharge channel 12 in the plasma address display device having the above configuration, the gas sealed in the discharge channel 12 is discharged. When ionized, plasma discharge occurs and is maintained at the anode potential.

When a data voltage is applied to the data electrode 5 in this state, the data voltage is applied to the liquid crystal layer 7 corresponding to the plurality of pixels 13 arranged in the column direction corresponding to the discharge channel 12 in which the plasma discharge has occurred. Written.

When the plasma discharge ends, the discharge channel 12 becomes a floating potential, and the data voltage written in the liquid crystal layer 7 corresponding to each pixel 13 is held until the next writing period (for example, after one field or one frame). Is done. In this case, the discharge channel 12 functions as a sampling switch, and the liquid crystal layer 7 of each pixel 13 functions as a sampling capacitor.

The liquid crystal operates by the data voltage written in the liquid crystal layer 7, and display is performed in pixel units. Therefore, the discharge channel 12 for generating the plasma discharge
Are sequentially scanned, and a data voltage is applied to each data electrode 5 in synchronization with the scanning, whereby the liquid crystal layer 7 is driven in the same manner as in the active matrix addressing method, and a two-dimensional image can be displayed.

The basic configuration of the plasma addressed display device has been described above. In this plasma addressed display device, the discharge address 9 (anode electrode 9A, cathode electrode 9
In order to connect K) to an external drive circuit, the terminal electrode 14 is formed as an external lead electrode as shown in FIG.

The terminal electrode 14 is directly connected to the discharge electrode 9 in the plasma cell. FIG. 5 shows an enlarged view of the connection between the terminal electrode 14 and the discharge electrode 9.

First, the discharge electrode 9 is formed in a stripe shape by applying a paste containing Ni and firing it.

The discharge electrode 9 is not formed directly on the lower substrate 8 but is formed via a base glass layer 15.

In this embodiment, the discharge electrode 9 and the underlying glass layer 15
Have been simultaneously etched by the sandblasting method, and thus have the same shape.

On the other hand, the terminal electrode 14 is
1, is drawn out of the plasma cell 2, and the tip of the plasma cell 2 is directly connected to the discharge electrode 9.

The terminal electrode 14 is made of the frit seal 11
It is formed by applying and baking a paste of gold (Au) or silver (Ag) in consideration of the adhesiveness to the like. Note that, as the paste used at this time, a gold paste that does not cause migration is preferable. In particular, by using a gold paste having a shrinkage rate of 25% or more during firing,
The solubility of mercury can be suppressed, and amalgamation can be further suppressed. Here, the shrinkage ratio of the gold paste can be calculated by comparing the film thickness before and after firing, and is specifically calculated by the following equation (2).

[0042]

(Equation 2)

The partition 10 formed on the discharge electrode 9
Must be formed slightly apart from the frit seal 11, and in this region, a cover glass 17 is formed to cover these electrodes. The area where the cover glass 17 is formed is a hatched area in FIG.

Here, amorphous glass is usually used as the cover glass layer 17 covering the joint of the electrodes. However, when an amorphous glass is used, a diffusion reaction occurs with the terminal electrode 14 and the discharge electrode 9, and the cover glass is damaged, causing abnormal discharge, or an abnormal resistance value at the junction between the electrodes 9 and 14. In some cases, heat is generated during discharge to cause disconnection due to a defect.

Therefore, in this plasma addressed display device, crystalline glass is used as the cover glass layer 17. Crystalline glass is required to be strictly controlled for the firing temperature and the like. However, since the flowability is small, it is difficult to cause a diffusion reaction with the electrodes 9 and 14, and it is possible to prevent an abnormal resistance value and disconnection at the electrode junction. And is superior to amorphous glass.

The cover glass layer 17 satisfies the following condition (3) when the coefficient of thermal expansion of the cover glass layer 17 is α ₁ and the coefficient of thermal expansion of the lower substrate 8 is α _2. desirable.

[0047]

(Equation 3)

[0048] If the thermal expansion coefficient alpha ₂ of the thermal expansion coefficient alpha ₁ and the lower substrate 8 of the cover glass layer 17 is out of this condition, i.e. when the difference alpha ₁ and alpha ₂ is large, the lower the time of firing the glass There is a high possibility that the side substrate will crack. In particular,
The coefficient of thermal expansion α ₁ of the cover glass layer 17 is set to 40 × 10 ^{−7 to} 6
0 × 10 ⁻⁷ / ° C., the coefficient of thermal expansion α ₂ of the lower substrate 8 is 35 × 1
It is realistic to set the range from 0 ^-7 to 50 × 10 ^-7 / ° C. In addition, these thermal expansion coefficients are values measured under temperature conditions of 30 to 300 ° C.

The thickness of the cover glass layer 17 after firing is preferably 10 μm or more, more preferably 30 μm or more. When the thickness of the cover glass layer 17 is less than 10 μm, abnormal discharge cannot be sufficiently prevented.
Further, in order to sufficiently secure the airtightness of the plasma cell, the thickness of the cover glass layer needs to be 30 μm or more.

[0050]

As is clear from the above description, in the present invention, since crystalline glass is used as the cover glass layer covering the joint between the discharge electrode and the terminal electrode in the region between the partition and the frit seal, Diffusion reaction of the glass to the electrode joint is suppressed, and disconnection due to abnormal resistance of the electrode due to the diffusion reaction and abnormal discharge due to damage to the cover glass can be prevented.
Therefore, it is possible to improve the reliability of the plasma addressed display device.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing a configuration example of a plasma addressed display device with a part cut away.

FIG. 2 is a schematic sectional view illustrating a configuration example of a plasma addressed display device.

FIG. 3 is a schematic diagram showing an arrangement of data electrodes, discharge electrodes, and discharge channels.

FIG. 4 is a schematic plan view schematically showing a cover glass layer formation region.

FIG. 5 is a schematic cross-sectional view of a main part showing a cover glass layer forming region.

[Description of Signs] 1 electro-optical display cell, 2 plasma cell, 3 dielectric sheet, 4 upper substrate, 5 data electrode, 7 liquid crystal layer, 8
Lower electrode, 9 discharge electrode, 10 partition, 11 frit seal, 14 terminal electrode, 17 cover glass layer

Claims (3)

[Claims] 1. A dielectric thin plate is disposed with a predetermined gap on a first substrate having a plurality of discharge electrodes substantially parallel to each other formed on one main surface, and the periphery thereof is sealed by a seal portion. In the image display device, wherein a plasma cell is formed, and a second substrate on which an electrode substantially orthogonal to the discharge electrode is formed on the opposite surface of the dielectric thin plate via an electro-optic material layer, On the discharge electrode, a partition partitioning the plasma cell is formed apart from the seal portion, and at least in a region between the partition and the seal portion, a cover glass layer is formed covering each of the electrodes, An image display device, wherein the cover glass layer is made of crystalline glass. 2. The thermal expansion coefficient of the cover glass layer is α ₁ ,
_2. The image display device according to claim 1, wherein when the coefficient of thermal expansion of the substrate is α ₂ , the following condition is satisfied. (Equation 1) 3. The image display device according to claim 1, wherein the thickness of the cover glass layer is 10 μm or more.