JP2000067759A - Gas discharge display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide high brightness and high luminescent efficiency at low discharge voltage by forming a protecting layer containing alkali metal or a protecting layer formed by stacking a layer comprising alkali metal on an electrode on a discharge space side. SOLUTION: As alkali metal, cesium is especially preferable. As a material forming a protecting layer, an oxide and a composite oxide of alkali earth metals or other metal such as lanthanum are listed, but magnesium oxide is most preferable. The thickness of the protecting layer is preferable to be 5000-7500 Å. The alkali metal is contained in the protecting layer or formed as a layer on the protecting layer. In the case contained in the protecting layer, the content of alkali metal is preferable to be 100 ppm or more. In the case forming a layer on the protecting layer, the thickness of the layer is to be 10-100 Å. The layer of alkali metal is preferably formed in a resistance heating vapor deposition method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a gas discharge display device. More specifically, the present invention relates to a gas discharge display device having a low discharge voltage, high luminance, and high luminous efficiency.

[0002]

2. Description of the Related Art Conventionally, there has been known a gas discharge display device which displays information by causing a discharge gas sealed in a sealed discharge space to emit light (for example, Japanese Patent Publication No. 54-1979).
No. 22068, JP-A-3-16623). Of these publications, the gas discharge display device described in the former publication covers an electrode provided on a substrate with an insulating layer made of alumina, silicon dioxide or silicon nitride, and forms an alkali metal such as cesium on the insulating layer. Is provided. In this gas discharge display device, by replacing the lead-containing low-melting glass conventionally used as an insulating layer with the above-described material, the reaction between alkali metal and lead is prevented, and the discharge voltage of the secondary electron emission layer is reduced. We are trying to reduce it.

On the other hand, the gas discharge display device of the latter publication is an improvement of the former gas discharge display device, and aims at shortening the manufacturing time by encapsulating gaseous cesium in a discharge space. . However, in any of the gas discharge display devices disclosed in the above publications, there is a possibility that components generated in the gas discharge display device may be sputtered by plasma generated in the discharge space during discharge. To prevent this spatter,
A protective layer having excellent sputter resistance is generally provided in a portion in contact with the discharge space.

[0004] Here, characteristics required for the material constituting the protective layer include a high secondary electron emission ratio, excellent spatter resistance, and a long life in order to lower the discharge starting voltage. As a material that almost satisfies this property,
Generally, magnesium oxide (MgO) is used.

[0005]

SUMMARY OF THE INVENTION A gas discharge display device comprises:
As a thin full-color display device that can be used as a television by colorization, it is attracting attention especially as a large flat display for high-definition video. ing. Furthermore, development for consumer use,
In consideration of replacement with a CRT, it is necessary to achieve higher luminance and higher luminous efficiency in a state of a lower discharge voltage in order to permeate the world widely.

It is known that the discharge voltage largely depends on the secondary electron emission ratio of the protective layer. Although a material having a lower secondary electron emission ratio than MgO is also known, it has problems such as being chemically unstable or lacking in sputter resistance. on the other hand,
Materials having better sputter resistance than MgO have a problem that the discharge voltage is high. An object of the present invention is to achieve higher luminance and higher luminous efficiency at a lower discharge voltage.

[0007]

Means for Solving the Problems The present inventors have found that the presence of an alkali metal in or on a protective layer allows the protective layer to have a high discharge voltage at a low discharge voltage without impairing the spatter resistance. The present inventors have found that brightness and high luminous efficiency can be realized, and have reached the present invention. Thus, according to the present invention, at least a discharge space and an electrode, and a protective layer containing an alkali metal formed on the electrode on the discharge space side or a protective layer in which a layer made of an alkali metal is laminated are provided. A gas discharge display device is provided.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, the principle by which the discharge voltage can be reduced is considered as follows. Alkali metals such as cesium are positively charged atoms, and when this is adsorbed on the protective layer, the cesium is positively charged and the protective layer is negatively charged. At this time, the space charge layer formed by the charged protective layer bends the level from the surface to a certain depth. With this curvature, the surface level and the vacuum level are also reduced. The electron affinity will effectively decrease from χ to χeff. The bending depth is considered to be about 100 °, and the escape probability of excited electrons generated within this depth increases due to the substantial decrease in electron affinity. As a result, it is considered that the discharge voltage can be reduced.

The gas discharge display device of the present invention includes a gas discharge display device such as a plasma display panel (PDP) and a plasma addressed liquid crystal display device. Further, the present invention can be applied to any of an AC type and a DC type gas discharge display device. Alkali metals include lithium, sodium, potassium, rubidium, cesium and francium. Of these alkali metals, cesium is preferred.

The materials constituting the protective layer include alkaline earth metals such as magnesium, calcium, barium and strontium, lanthanum, yttrium, cerium, and the like.
Examples include oxides of other metals such as hafnium, and composite oxides. However, in the present invention, any material that can be generally used for the protective layer of the gas discharge display device can be used without being limited to these materials. A particularly preferred material is MgO. The thickness of the protective layer is preferably 5000 to 7500 °.

Here, the alkali metal may be contained in the protective layer, or a layer may be formed on the protective layer. When contained in the protective layer, the alkali metal is 100 pp
m or more, preferably 500 to 1000
More preferably, it is contained in ppm. When the amount is less than 100 ppm, the effect of reducing the discharge voltage is not produced, which is not preferable. On the other hand, if it is more than 1000 ppm, it becomes difficult to form a protective layer, which is not preferable. When a layer is formed on the protective layer, the thickness of the layer is 1
Preferably it is 0-100 °. If the thickness is less than 10 °, the effect of reducing the discharge voltage will not be produced, and it will be difficult to uniformly dispose it on the protective layer. When the thickness is more than 100 °, it is not preferable because electron emission from the protective layer is hindered. Particularly preferably, the alkali metal is either contained in the protective layer at 500-1000 ppm or is present on the protective layer as a layer with a thickness of 10-100 °.

It has been known that alkali metals are generally highly reactive and therefore difficult to form a uniform film. However, the device of the present invention can be uniformly present on the surface of the protective layer by the following method. Specifically, when a layer made of an alkali metal is formed on the protective layer, examples of the formation method include a resistance heating evaporation method and a sputtering method. Among these, the resistance heating evaporation method is preferable, and the conditions are preferably performed under the conditions of an evaporation pressure of 5 × 10 ^{−5 to} 5 × 10 ⁻⁴ torr and a temperature of 100 to 150 ° C. When an alkali metal is contained in the protective layer, a method in which an alkali metal is added to a deposition source or a method in which a protective layer is formed by vapor deposition while irradiating alkali metal ions, protection using a paste containing an alkali metal alkoxide is performed. A method of forming a layer by a printing method and the like can be given. Further, there is also a method of depositing the alkali metal on the protective layer by introducing a gas generated by heating the alkali metal at the same time as introducing the discharge gas into the discharge space. In the case of this method, gaseous alkali metal can be present in the discharge space at the time of discharge, so that discharge characteristics can be improved.

Next, the material constituting the electrode under the protective layer is not particularly limited, and any known material can be used. Such materials include metals such as nickel, cobalt, copper, zinc, chromium, iron,
Alloys of these metals are mentioned. In addition, ITO, NES
A transparent metal oxide such as A can also be used as a material for the electrode.

Next, a discharge space is usually formed between a pair of substrates, and the electrodes and the protective layer are formed on at least one of the substrates. The substrate that can be used in the present invention is not particularly limited, and may be an inorganic insulating substrate such as a Pyrex glass substrate, a soda lime glass substrate, or a ceramic substrate, or an inorganic insulating substrate such as a silicon substrate having an inorganic insulating film formed on the surface. A semiconductor substrate; Of these, it is preferable to use an inorganic insulating substrate.

The gas discharge display of the present invention is preferably an AC type gas discharge display having a dielectric layer. In this device, the protective layer is formed on the dielectric layer. Therefore, the dielectric layer can be protected from the plasma generated in the discharge space by the protective layer, and the discharge voltage can be reduced by the alkali metal present in or on the protective layer. As the dielectric layer, a layer made of low-melting glass is usually used. Note that, instead of the low melting point glass, a material forming the protective layer may be used as a material of the dielectric layer.

Here, the configuration of a more specific AC type and surface discharge type PDP will be described. General said P
FIG. 1 shows the configuration of the DP. It should be noted that the present invention can be used for PDPs of other driving systems and / or structures.
The PDP 20 includes a display substrate and a rear substrate. The display-side substrate includes a metal film 26 (for example, a laminated film of Cr / Cu / Cr, Al) serving as a bus electrode and a transparent electrode 25 (for example, ITO, NE) on an inorganic substrate 27 (for example, a glass substrate).
A display electrode made of SA (SnO ₂ )) is formed in a stripe shape, and a dielectric layer 24 is formed so as to cover the electrode. A protective layer 29 containing an alkali metal is formed on the dielectric layer 24.
Is formed. When a layer made of an alkali metal is formed, the layer is usually formed of a protective layer 2
9 on the entire surface. On the other hand, the back substrate is an inorganic substrate 2
3 (for example, a glass substrate), the address electrodes A are formed in a stripe shape, the address electrodes A are covered with a dielectric layer 28, and the partition 21 is formed on the dielectric layer 28, and the partition 21 is formed.
It has a configuration in which the phosphor layer 22 of the three primary colors of RGB is covered on the dielectric layer 28 therebetween and the wall surface of the partition wall. FIG.
In the figure, D indicates a display surface, EU indicates a unit light emitting element, and EG indicates one pixel.

[0017]

The present invention will be described below in more detail with reference to examples. Example 1 A transparent electrode having a thickness of about 0.3 μm was formed on a substrate made of soda lime glass. Next, on the transparent electrode, about 3
A bus electrode having a thickness of μm was formed. Next, a dielectric layer having a thickness of about 50 μm was formed so as to cover the bus electrode and the transparent electrode.

Further, on the dielectric layer, about 60
A display-side substrate was obtained by forming a protective layer made of MgO of 00 °. When forming the protective layer, MgO containing 100 ppm of cesium (purity 99.
99%). Separately from the display side substrate, an address electrode having a thickness of about 2 μm was laminated on a soda lime glass substrate. Subsequently, a back substrate was able to be manufactured by forming a dielectric layer, partition walls, and a phosphor layer by known means.

The display-side substrate and the back substrate were bonded at an interval of about 200 μm, and a discharge gas was filled in the discharge space, whereby an AC type surface discharge type PDP could be obtained. Examples 2 and 3 The vapor deposition source contained 500 ppm of cesium (Example 2) and 10 ppm.
A PDP was prepared in the same manner as in Example 1 except that it contained 00 ppm (Example 3).

Example 4 A cesium-free deposition source was used.
Except for irradiating the protective layer with cesium ions with a gun,
A PDP was prepared in the same manner as in Example 1. Of ion irradiation
The conditions are as follows: acceleration voltage 400 V, current density on the protective layer surface
10 μA / cm ^TwoAnd The resulting protective layer is a secondary ion
Approximately 1000p as measured by mass spectrometry (SIMS)
pm of cesium.

Example 5 A PDP was produced in the same manner as in Example 1 except that a cesium gas heated and vaporized was sealed in a discharge space at the same time as a discharge gas using an evaporation source containing no cesium.

Example 6 A PDP was prepared in the same manner as in Example 1, except that a cesium-free deposition source was used, and a layer made of cesium having a thickness of 10 ° was formed on the protective layer by resistance heating deposition. did.

Example 7 The protective layer was formed such that the cesium concentration was 10
A PDP was produced in the same manner as in Example 1, except that the paste was added by a printing method using a paste to which cesium alkoxide was added so as to be 00 ppm.

Comparative Example 1 A PDP was prepared in the same manner as in Example 1 except that an evaporation source containing no cesium was used.

Comparative Examples 2 and 3 Cesium was added at 10 ppm (Comparative Example 2) and 50 p
Except for including pm (Comparative Example 3), a PDP was prepared in the same manner as in Example 1. Examples 1 to 3 and Comparative Examples 1 to
The discharge starting voltage of PDP No. 3 was measured, and the relationship with the amount of cesium added was shown in FIG. Further, the discharge starting voltages of Examples 4 to 7 were 174 V, 169 V, 170 V, and 178 V, respectively. From FIG. 2 and Examples 4 to 7, it was found that when cesium was contained in the protective layer, or when a layer made of cesium was formed on the protective layer, the firing voltage could be reduced.

Further, with respect to Examples 3, 4 and 7, the change over time in the discharge voltage was measured, and the results are shown in FIG. From FIG. 3, it was found that when cesium was included in the protective layer by ion irradiation or printing, the change in discharge voltage with time was smaller than that in the case where cesium was included by evaporation. When the protective layers of Examples 3, 4 and 7 were measured by SIMS, the protective layer formed by the vapor deposition method had a cesium concentration gradually decreasing from the dielectric layer side. In contrast, when cesium was included in the protective layer by ion irradiation or printing, the cesium concentration did not change. From this result, it was found that a change in the concentration of cesium in the protective layer leads to a temporal deterioration of the discharge voltage.

[0027]

According to the present invention, a gas discharge display device having high luminance and high luminous efficiency can be obtained at a lower discharge voltage.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of a PDP.

FIG. 2 is a graph showing the relationship between the discharge starting voltage and the amount of cesium added to the PDPs of Examples 1 to 3 and Comparative Examples 1 to 3.

FIG. 3 is a graph showing the discharge voltage of each of the PDPs of Examples 3, 4 and 7 over time.

[Explanation of symbols]

 Reference Signs List 20 PDP 21 Partition wall 22 Phosphor 23, 27 Inorganic substrate 24, 28 Dielectric layer 25 Transparent electrode 26 Metal film 29 Protective layer A Address electrode D Display surface EU Unit light emitting element EG 1 pixel

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Manabu Ishimoto 4-1-1 Kamikadanaka, Nakahara-ku, Kawasaki-shi, Kanagawa F-term in Fujitsu Limited (reference) 5C040 AA01 AA02 DD11

Claims (2)

[Claims] 1. An electrode comprising at least a discharge space and an electrode, and a protective layer containing an alkali metal or a protective layer formed by laminating a layer made of an alkali metal formed on the electrode on the discharge space side. Gas discharge display device. 2. The method according to claim 1, wherein the alkali metal is cesium, the protective layer is made of magnesium oxide, and cesium is contained in the protective layer.
The gas discharge display device according to claim 1, which is contained at a concentration of 00 ppm or more.