JP2000330095A - Plasma address display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress abnormal arc discharge generated in a plasma cell of an AC driven plasma address display device. SOLUTION: This plasma address display device has a laminated structure where a display cell 1 provided with columns of signal electrodes Y and a plasma cell 2 provided with rows of discharge channels 5 are laminated on each other. Line sequential scanning is performed on the plasma cell 2 by exciting plasma discharge by sequentially applying selecting pulses across a pair of discharge electrodes X1, X2 arranged in a discharge channel 5, while image signals are applied to each signal electrode Y of the display cell 1 in synchronization with the line sequential scanning, for displaying an image. A pair of the discharge electrodes X1, X2 arranged on one discharge channel 5 enclosed by a pair of partition walls 7 are coated with a dielectric film 17, and AC plasma discharge is excited by making use of the dielectric property. Discharge electrodes X1, X2 each have a laminated structure wherein a transparent electrode 15 formed of a transparent conductive film 15 and a bus electrode 16 formed of a metallic film are laminated on each other. The bus electrode 16 is hidden on the bottom of the adjoining partition walls 7, while the transparent electrode 15 is open on the side from the bottom part of the partition walls 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma addressed display device in which a display cell and a plasma cell are overlapped with each other. More specifically, the present invention relates to a discharge electrode structure of an AC drive type plasma cell.

[0002]

2. Description of the Related Art FIG. 5 is a schematic partial sectional view showing a typical structure of an AC drive type plasma addressed display device. As shown in the drawing, the AC-driven plasma addressed display device is partitioned by partitions 7 parallel to each other on the glass substrate 4 on the back side, and is supported by the partitions 7 so as to be parallel to the substrate 4 on the back side. And a discharge channel 5 hermetically sealed by the intermediate sheet 3. A peripheral portion (not shown) of the intermediate sheet 3 is sealed with respect to the rear substrate 4 by, for example, a frit seal material, and the space between the intermediate sheet 3 and the rear substrate 4 is sealed. The closed space is filled with a discharge gas.
Further, a front substrate 8 on which the signal electrodes Y are provided is attached to the intermediate sheet 3. The signal electrode Y is formed on the rear surface of the front substrate 8. Liquid crystal 9 is filled between the front substrate 8 and the intermediate sheet 3 to form a liquid crystal layer.

The discharge channel 5 is provided with a pair of discharge electrodes X1 and X2 covered with a dielectric film 17. A reference electrode 19 is provided at an intermediate portion of the partition wall 7. Each of the discharge electrodes X1 and X2 has a laminated structure of a wide transparent electrode 15 and a narrow bus electrode 16. The transparent electrode 15 is made of, for example, ITO and has a thickness of several hundred nm. On the other hand, the bus electrode 16 is made of, for example, Cr / Cu
/ Cr laminated structure. Since the bus electrode 16 is formed of an opaque metal film, its width and position are restricted from an optical point of view. This is because the opaque bus electrode 16 lowers the aperture ratio. In addition, a predetermined signal voltage is not applied to the liquid crystal 9 to the partition 7 and its vicinity. Therefore, it is desirable that the partition 7 and the vicinity thereof be shielded from light. Therefore, from an optical point of view, it is desirable that the bus electrode 16 be provided at a position where the vicinity of the partition wall 7 can be shielded from light. That is, in one discharge channel 5, the bus electrode 16 is provided at a position near the partition 7, and the transparent electrode 15 extends to the center side of the discharge channel 5.

[0004] In the case of a transmission type display device, the dielectric film 17 must be formed of a transparent material. The dielectric film 17 made of a transparent material can be formed by a method of forming a low-melting glass paste by screen printing or a method of depositing a low-melting glass powder on an electrode surface by an electrodeposition method. On the dielectric film 17, a MgO film 18 which is a functional film
Is provided. As described above, in the AC drive type, the surfaces of the discharge electrodes X1 and X2 are not exposed, and the dielectric film 17
The discharge when the MgO film 18 exists is a so-called AC plasma discharge. That is, when the selection pulse applied between the pair of discharge electrodes X1 and X2 exceeds the discharge start voltage and discharge starts, the capacitance of the dielectric film 17 is charged by the discharge electrodes. When this charging ends, the plasma discharge automatically ends. In the case of the DC drive type, the surface of the discharge electrode is not covered with the dielectric film but is exposed. One of the pair of discharge electrodes becomes an anode and the other becomes a cathode, and a DC plasma discharge is generated between the two.

[0005]

An AC-driven plasma addressed display device has a more complicated structure than a DC-driven plasma addressed display device.
The film 18 can be formed on the dielectric film 17. The MgO film 18 has a relatively low work function and a good emission efficiency of secondary electrons required for plasma discharge, and also has excellent sputter resistance, and thus is highly useful in terms of the life of the display device. Since the MgO film 18 is insulative, a DC drive type cannot form an MgO film on the surface of the discharge electrode. On the other hand, a transparent electrode 15 made of ITO or the like is used as an electrode material in order to maximize the transmittance of the display device. However, since ITO is a material having a relatively high resistance value, in order to reduce the resistance of the wiring when increasing the size of the display device, for example, a bus wiring 16 of three layers of Cr / Cu / Cr is provided so as to overlap the transparent electrode 15. When a uniform discharge is sustained by this structure, the transmittance is small and the discharge voltage is stable, and the AC-driven plasma addressed display is superior to the conventional DC-driven plasma addressed display. The result is obtained. However, in practice, a uniform discharge state is not always maintained, and there is a case where an arc-like discharge occurs, the electrode is damaged, and the discharge channel cannot be scanned.

[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 basically has a stacked structure in which display cells having column-shaped signal electrodes and plasma cells having row-shaped discharge channels are stacked on each other. Line-sequential scanning of the plasma cell is performed by sequentially applying a selection pulse between a pair of discharge electrodes provided in each discharge channel to excite the plasma discharge, and each signal electrode of the display cell is synchronized with the line-sequential scanning. To apply an image signal to display an image. The row-shaped discharge channels are separated from each other by partition walls. A pair of discharge electrodes provided in one discharge channel surrounded by a pair of partition walls are covered with a dielectric film, and excite a plasma discharge by utilizing the dielectric properties. Each discharge electrode has a laminated structure in which a transparent electrode made of a transparent conductive film and a bus electrode made of a metal film are stacked. As a feature, the bus electrode is hidden at the bottom of an adjacent partition, while the transparent electrode is exposed laterally from the bottom of the partition. Specifically, the bus electrode is made of a metal film containing at least Cu, while the dielectric film is made of a low-melting glass containing at least PbO. More specifically, the bus electrode is formed of a three-layered metal film of Cr / Cu / Cr. The dielectric film is covered with an MgO film.

The bus electrode has, for example, a three-layer structure of Cr / Cu / Cr. The dielectric film covering this is, for example, PbO
And a low-melting glass containing Both are in contact with each other and may react with each other due to various heat treatments during the manufacturing process. When a chemical reaction occurs between the constituent material of the bus electrode and the constituent material of the dielectric film, foaming may be caused, thereby generating a pinhole in the dielectric film. This pinhole may cause arc-shaped abnormal discharge. Therefore, in the present invention, by disposing the bus electrode at the bottom of the partition,
I try to prevent the negative effects.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic diagram showing an embodiment of a plasma addressed display device according to the present invention. As shown in the figure, the present plasma address display device has a stacked structure in which a display cell 1 having a column-shaped signal electrode Y and a plasma cell 2 having a row-shaped discharge channel 5 are overlapped with each other. An intermediate sheet 3 made of thin glass or the like is interposed between the display cell 1 and the plasma cell 2. By sequentially applying a selection pulse between a pair of discharge electrodes X1 and X2 provided in each discharge channel 5 to excite a plasma discharge, line sequential scanning of the plasma cell 2 is performed. In addition, an image signal is applied to each signal electrode Y of the display cell 1 in synchronization with the line-sequential scanning to display an image. The signal electrode Y is formed by patterning a transparent conductive film such as ITO in a stripe shape. The display cell 1 is formed using the upper glass substrate 8, and a color filter 13 is formed on the inner surface thereof in addition to the signal electrode Y described above. The glass substrate 8 is bonded to the intermediate sheet 3 at a predetermined gap, and this gap is filled with an electro-optical material such as a liquid crystal 9.

The row-shaped discharge channels 5 are separated from each other by partition walls 7. This partition 7 is a lower glass substrate 4
It is formed in. For example, the partition wall 7 can be formed by printing and firing a low-melting glass paste. Each discharge channel 5 surrounded by a pair of partition walls 7, 7 has
It is filled with an ionizable gas. As this gas, for example, an inert gas such as helium, argon, neon, xenon, and krypton can be used. Further, a pair of discharge electrodes X1 and X2 provided in each discharge channel 5 are covered with a dielectric film 17, and use the dielectric properties to excite plasma discharge. Each of the discharge electrodes X1 and X2 has a laminated structure in which a transparent electrode 15 made of a transparent conductive film such as ITO and a bus electrode 16 made of a metal film are stacked. As a feature, the bus electrode 16 is hidden at the bottom of the adjacent partition 7, while the transparent electrode 15 is exposed from the bottom of the partition 7 to the side.

In this embodiment, the bus electrode 16 is made of a metal film containing at least Cu. More specifically, the bus electrode 16 is formed of a three-layer Cr / Cu / Cr metal film. This bus electrode 16 secures the necessary conductivity as wiring with an intermediate Cu layer, secures adhesion to the glass substrate 4 with a lower Cr layer, and protects the intermediate Cu layer with an upper Cr layer. .
On the other hand, the dielectric film 17 is made of low-melting glass containing at least PbO, and is formed by, for example, printing and firing.
In general, a plasma addressed display device uses a glass plate as a substrate 4
Is used, the dielectric film 17 has a lower melting point than P
It is necessary to use a low melting point glass paste containing bO. In this case, Cu contained in the bus electrode 16 may chemically react with PbO contained in the dielectric film 17,
To protect the discharge channel 5 from this adverse effect, the bus electrode 1
6 is hidden at the bottom of the partition wall 7. Since the main purpose of the bus electrode 16 is to ensure conductivity as a wiring, there is no problem in the optical function even if it is disposed immediately below the partition wall 7. Since the transparent electrode 15 extends toward the center of the discharge channel 5, it is possible to generate a uniform plasma discharge inside the discharge channel 5. The dielectric film 17 is covered with an MgO film 18. This MgO film 18
Has a low work function and a high secondary electron emission efficiency required for maintaining the plasma discharge, and also has excellent sputter resistance. The plasma discharge reduces the dielectric film 17 and the discharge electrodes X1 and X1.
2 is protected.

With continued reference to FIG. 1, the shape and size of the present plasma addressed display device and a method of manufacturing the same will be described in detail.
As shown, the arrangement pitch of the discharge channels 5 is 110
0 μm. The bus electrode 16 and the transparent electrode 15 each having a three-layer structure of Cr / Cu / Cr were formed by sputtering. The thickness of each layer of Cr / Cu / Cr is 0.1 μm / 2 μm / 0.1 μm. In addition, ITO
The transparent electrode 15 made of is 0.47 μm thick. The width of the bus electrode 16 is 75 μm, and the width of the transparent electrode 15 is 475.
μm. The gap between the pair of discharge electrodes X1 and X2 is 50 μm. As described above, the dielectric film 1
7 and the partition 7 were formed by a printing method. The material of the dielectric film 17 was NP-7972G (manufactured by Noritake Instruments Co., Ltd.), which is a kind of low-melting glass, and the thickness was set to 40 μm. Also,
The material of the partition walls 7 is also a kind of low melting point glass paste and is NP-7.
854G (manufactured by Noritake Instruments) was used. The width and height of the partition 7 are 300 μm and 200 μm, respectively. The discharge gas filling the discharge channel 5 is He / Xe
Was used. The content of Xe is 3%. The discharge gas pressure is 190 Torr. When the plasma address display device thus manufactured was continuously turned on, uniform discharge was maintained, and no arc-shaped abnormal discharge occurred.

As a comparative example, a plasma addressed display device having an electrode structure as shown in FIG. 2 was manufactured. Basically,
It is similar to the embodiment shown in FIG. 1, and corresponding parts are denoted by corresponding reference numerals. The difference of this comparative example from the present embodiment is that the bus electrode 16 having a three-layer structure of Cr / Cu / Cr is not hidden at the bottom of the partition wall 7,
That is, it is arranged in the discharge channel 5. This has the advantage that the aperture ratio is higher than in the embodiment shown in FIG. That is, in this comparative example, there is no need to hide the bus electrode 16 at the bottom of the partition 7, so that the thickness of the partition 7 can be reduced to 200 μm. On the other hand, in the embodiment shown in FIG. 1, the width of the partition 7 is 300 μm in order to hide the bus electrode 16 at the bottom of the partition 7. However, when 10 panels of the comparative example thus manufactured were lit, five abnormal discharges occurred during initial aging (within 30 hours after lighting).

As a result of the failure analysis, it was found that the abnormal arc-like discharge was caused by the pinhole PH existing in the dielectric film 17. That is, when the pinhole PH exists in the dielectric film 17, when a driving voltage is applied, the portion of the pinhole PH causes insulation breakdown due to insufficient withstand voltage, and an arc-shaped discharge occurs. Further investigation revealed that the pinholes were concentrated in the dielectric film 17 near the bus electrode 16. In this pinhole PH, the bus electrode 16 and the dielectric film 17 chemically react,
It is caused by foaming. The dielectric film 17 is formed by printing and firing a paste of lead glass powder. When the lead glass is melted during firing, it reacts with Cu contained in the bus electrode 16. Alternatively, when the partition 7 is printed and baked after the formation of the dielectric film 17, the lead glass component contained in the dielectric film 17 is remelted and reacts with the three-layer bus electrode 16 of Cr / Cu / Cr. . As a result of investigation, it has been found that this problem can be solved by adopting the structure as shown in FIG. That is, in the structure shown in FIG. 1, the bus electrode 16 is provided below the partition 7. In this case, even when the dielectric film 17 and the bus electrode 16 react and foam, the arc-shaped abnormal discharge does not occur due to the presence of the partition wall 7 thereon.

FIG. 3 is a photomicrograph of the comparative example shown in FIG. This micrograph was taken at a magnification of 30 times, and shows three partition walls and four discharge channels in the visual field. Pinholes indicated by arrows are clearly observed in the second discharge channel and the third discharge channel from the left. Although it is a little difficult to see, pinholes are also observed in the first discharge channel. These pinholes are in the immediate vicinity of the partition wall and are generated by a reaction between the bus electrode and the dielectric film.

FIG. 4 is a photomicrograph at a magnification of 300 times, which is an enlarged view of one pinhole. Pinholes generated near the partition walls cause abnormal arc-like discharge.

[0016]

As described above, according to the present invention,
In an AC-driven plasma addressed display device, the bus electrode forming the upper layer of the discharge electrode is hidden at the bottom of an adjacent partition, while the transparent electrode forming the lower layer is exposed laterally from the bottom of the partition. . With such an electrode configuration, uniform AC plasma discharge is maintained, and a highly reliable plasma addressed display device can be manufactured.

[Brief description of the drawings]

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

FIG. 2 is a partial sectional view showing a comparative example of the plasma addressed display device.

FIG. 3 is a micrograph of a comparative example.

FIG. 4 is a micrograph of a comparative example.

FIG. 5 is a schematic partial cross-sectional view showing a typical configuration of an AC drive type plasma addressed display device.

[Description of Signs] 1 ... Display cell, 2 ... Plasma cell, 3 ... Intermediate sheet, 4 ... Glass substrate, 5 ... Discharge channel, 7 ... Partition, 8 ... Glass substrate, 9 liquid crystal, 15 transparent electrode, 16 bus electrode, 17
..Dielectric film, 18: MgO film, X1: discharge electrode, X2: discharge electrode, Y: signal electrode.

Continued on the front page F term (reference) 2H089 HA36 QA16 5C040 FA01 FA09 GB03 GC05 GC06 GC12 MA20 5C094 AA03 AA24 AA37 AA55 AA60 BA43 CA19 DA13 DA14 DB04 DB10 EA04 EA05 EA10 EB02 FA01 FA02 FB02 FB12 FB20 GA10

Claims (4)

[Claims] 1. A stacked structure in which a display cell having a column-shaped signal electrode and a plasma cell having a row-shaped discharge channel are stacked on each other, and between a pair of discharge electrodes provided in each discharge channel sequentially. A plasma address for performing line sequential scanning of a plasma cell by applying a selection pulse to excite a plasma discharge and applying an image signal to each signal electrode of a display cell in synchronization with the line sequential scanning to perform image display In the display device, the row-shaped discharge channels are separated from each other by partition walls, and a pair of discharge electrodes provided in one discharge channel surrounded by the pair of partition walls are covered with a dielectric film, and the dielectric property thereof is reduced. Each discharge electrode has a laminated structure in which a transparent electrode made of a transparent conductive film and a bus electrode made of a metal film are overlapped, and the bus electrode is used to form an adjacent partition wall. While hidden at the bottom,
The plasma addressed display device, wherein the transparent electrode is exposed laterally from a bottom of the partition. 2. The plasma addressed display device according to claim 1, wherein said bus electrode is made of a metal film containing at least Cu, and said dielectric film is made of a low-melting glass containing at least PbO. 3. The plasma addressed display device according to claim 2, wherein said bus electrode is formed of a three-layered metal film of Cr / Cu / Cr. 4. The plasma addressed display device according to claim 2, wherein said dielectric film is covered with an MgO film.