JPH07288086A - Gas discharge tube and dielectric composition - Google Patents

Abstract

PURPOSE:To improve a discharge characteristic, and facilitate manufacture by forming a protective layer of a discharge surface of a discharge electrode as a film which contains a prescribed dielectric or the like and has porosity not more than 30%. CONSTITUTION:Line-shaped display discharge electrodes Sx and Sy are formed in the vertical direction on a front glass plate FG, and a covering dielectric DL is formed on this as a surface protective layer. In order to improve light transmission, the Sx and the Sy are formed in a thin line, or is formed of a transparent electrode material, for example, an ITO (InaSn oxide) film, and light transmissivity is enhanced. The protective layer is formed as a film which contains a chemical formula AX or a thermally decomposed material of this and a dielectric containg at least a single kind of component melted at a temperature not higher than 850 deg.C and has porosity not more than 30%. A of the chemical formula is composed of an element capable of forming a stable oxide dielectric not less than 1000 deg.C, and X is composed of a group selected from respective groups such as F, Cl and Br. Oxide which belongs to an I to IIIa group of an element periodic table and is selected from the atomic number not more than 71 is contained in material powder.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas discharge tube and a dielectric composition useful for the same, and more particularly to a gas discharge tube which is excellent in gas discharge characteristics and easy to manufacture and a dielectric useful for coating the discharge electrode thereof. Body composition.

[0002]

2. Description of the Related Art Conventionally, many gas discharge tubes (hereinafter abbreviated as discharge tubes) such as fluorescent lamps and plasma display panels (hereinafter abbreviated as PDP) are known. Among these discharge tubes, the discharge tube having an electrode coated with a dielectric is applied to an AC-driven discharge tube. Further, even in a DC-driven discharge tube, an electrode covered with a dielectric can be applied to an ion generating electrode or the like. Although there are many factors that affect the discharge characteristics of such discharge tubes, the characteristics of the dielectric material in contact with the discharge surface are the largest that affect the discharge characteristics.
In the following, a PDP having a complicated structure will be described as an example.

In the PDP, two or more flat substrates are used so that a large number of display cells can be easily formed and a thin type can be achieved. A transparent glass front plate is used for the display surface. Although various materials can be applied to the back plate, inexpensive soda lime glass for windows is used for both. The front and rear plates facing each other are sealed with seal glass to form an airtight container for containing the discharge gas. Usually, an exhaust hole formed in the back plate and a chip tube connected thereto are used to introduce a discharge gas after exhausting the inside of the container and chip off the chip tube to complete the PDP.

An example of a general PDP structure is shown in FIG. 1 as a partial schematic sectional view.

In FIG. 1, line-shaped display discharge electrodes Sx and Sy are vertically formed on a front glass plate FG, and a coating dielectric DL is formed thereon as a surface protection layer. Sx and Sy are formed in a thin line shape in order to improve light transmission, or a transparent electrode material such as ITO (In-
Sn oxide) film to increase the light transmittance. Normally, the coating dielectric of the display discharge electrode is composed of a glass layer and a surface protective layer, but like the electrode, a transparent glass layer is selected, and the protective layer is usually a thin vapor deposition film such as MgO. This protective layer also has a good light transmittance. Line-shaped write electrodes W are formed on the back plate BP in a direction orthogonal to Sx and Sy, and the surface thereof is covered with a phosphor PH powder. An address pulse is applied to one of Sx and Sy together with a display discharge pulse and also serves as an address electrode. 1 at the intersection of this and the write electrode when viewed from the display direction.
The two display cells correspond. Usually, electrodes dedicated to display discharge are commonly connected. A partition wall that is also a spacer between the front plate and the rear plate is formed between each cell, and functions to prevent erroneous discharge between adjacent cells and color bleeding. In FIG. 1, it is omitted because it is a partition wall parallel to the write electrode. The cell spacing in the horizontal direction is maintained at a distance that does not cause erroneous discharge. As the discharge gas, one that emits ultraviolet rays such as Xe is selected, and it is sealed alone or together with another rare gas.

The above-mentioned PDP is classified as a surface discharge type because display discharge occurs in a direction parallel to the substrate. This surface discharge type is devised so as to prevent the phosphor from being deteriorated by the ions generated by the discharge. Further, in this configuration, since the light emission of the phosphor is directly observed, it is classified as a reflection type. There is also a configuration in which the display is viewed from the back plate side of FIG. In this case, since the light emission is seen through the phosphor film, it is classified as a transmissive type, and naturally the writing electrode must be made of a material having a high light transmissivity. If the transmissive phosphor coating area is the same as that of the reflective type, the reflective type can realize about 60% higher brightness than the transmissive type.

Conventionally, various materials have been studied as the covering dielectric material, but the mainstream at present is MgO. It is known that the MgO film illustrated in FIG. 1 is formed by applying a thin film technique and has a high secondary electron emissivity (hereinafter referred to as γ). However, the thin film technology is expensive because the equipment is expensive and the mass productivity is poor.
On the other hand, as a coating dielectric for the display discharge electrode, a thickness of about 20 to 60 μm has been conventionally used in order to increase the withstand voltage and appropriately reduce the electrostatic capacitance. If this coating is made of MgO alone, not only becomes more expensive, but the coating film is likely to peel off due to the difference in thermal expansion from the substrate. Therefore, a two-layer structure of a MgO layer of 1 μm or less and a glass is usually adopted, but the two steps are complicated in PDP manufacturing.

Methods for improving these have also been investigated.
For example, by applying an inexpensive thick film technology, MgO, Mg
Powder such as (OH) ₂ is used. These powders are kneaded with a liquid vehicle so as to have printability. On the printed film, the liquid vehicle is scattered during the thermal process of drying and baking,
g (OH) ₂ is decomposed into MgO to form a powdery protective layer. There are roughly two types of thick film technology.

The first method does not use a high temperature adhesive. The disadvantages are that the protective material powder is non-adhesive, its adhesive force after firing is weak, and the workability of PDP assembly is poor. Also,
Since the protective layer obtained by powder filling has a porosity of 40% or more, it has a low withstand voltage and is easily affected by the underlying glass layer. Furthermore, since the surface is rough, reflecting the particle size of the powder, the characteristics vary greatly among many discharge cells. This results in a smaller operating margin. The operation margin is represented by the difference between the minimum of the maximum lighting voltages of each cell and the maximum of the minimum sustaining voltages. The maximum lighting voltage is the upper limit value of the lighting voltage in the addressable range.

The second method uses a fixing agent.
If you mix the low melting point glass of the general adhesive with the protective material,
A dense and smooth film is formed and the adhesion is good. However, the low melting point glass impairs the stability of the discharge characteristics.

Therefore, it is not possible to obtain the results of simultaneously satisfying the denseness, smoothness and discharge characteristics of the coating film by the two conventional methods as described above. Further, a drawback common to both is that the protective layer has a small light transmittance, and therefore cannot be used in a surface discharge type or a reflection type PDP which requires high brightness.

As is clear from the above description, the conventional P
In the current situation, DP cannot achieve both the easy and inexpensive process and the excellent characteristics.

[0013]

DISCLOSURE OF THE INVENTION The present invention solves these problems of the prior art and provides a gas discharge tube having excellent discharge characteristics and easy to manufacture, and a dielectric composition for coating a discharge electrode, which is useful for the gas discharge tube. The purpose is to provide.

[0014]

As a result of various studies on these problems of the prior art, the present inventors have completed the present invention for solving the above problems.

The above object of the present invention can be achieved by the following gas discharge tube.

That is, the first aspect of the present invention is a gas discharge tube in which a discharge electrode is formed in a container containing a discharge gas, the protective layer on the surface of the discharge electrode having the following 1),
85 with the chemical formula AX shown in 2) or this thermal decomposition product.
A gas discharge tube comprising a dielectric containing at least one component that melts at 0 ° C. or less and formed as a film having a porosity of 30% or less.

1) A in the chemical formula is a melting point of 1000 ° C. or higher,
It is composed of elements having a volume resistance of 1 × 10 ¹³ Ω · cm or more and capable of forming a stable oxide dielectric.

2) X in the chemical formula is F, Cl, Br, I,
It is composed of at least one group selected from each group of SO _{4 ,} NO _{3 ,} CO _{3 ,} CN and OH.

Further, it is achieved by the following dielectric composition for coating a discharge electrode of a gas discharge tube.

That is, the second aspect of the present invention is the dielectric powder 1
A dielectric composition in which 00 parts by weight and 25 to 70 parts by weight of a liquid vehicle are kneaded, wherein the powder has the following 1) and 2).
850 ℃ with the chemical formula AX shown in or the thermal decomposition product
A dielectric composition for coating a discharge electrode of a gas discharge tube, which comprises at least one component having the following melting point.

1) A in the chemical formula is a melting point of 1000 ° C. or higher,
It is composed of elements having a volume resistance of 1 × 10 ¹³ Ω · cm or more and capable of forming a stable oxide dielectric.

2) X in the chemical formula is F, Cl, Br, I,
It is composed of at least one group selected from each group of SO _{4 ,} NO _{3 ,} CO _{3 ,} CN and OH.

The present invention will be described in more detail below.
A form to which the simplest thick film technique can be applied will be mainly described.

The best protective layer for achieving the objects of the present invention is
It is to form a dense and smooth film using a stable material having a large γ. The present inventors, by dispersing an oxide having a large γ in a specific material that can be melted in the heating step,
The inventors have found that a protective layer having characteristics equal to or higher than those of conventional ones can be manufactured more easily and cheaply than the conventional PDP manufacturing process, and completed the present invention.

The characteristics required for the protective layer as the covering dielectric for the display discharge electrode are that it is stable against discharge and that the discharge voltage can be lowered. Of course, the durability of the PDP formation process and the price are also examined. Further, in the case of forming a coating dielectric on the front glass plate in a reflective PDP or the like, transparency is also important. A substance having a high γ is suitable for lowering the discharge voltage, but generally, the periodic table I
˜IIIa group elements are preferable, and oxides containing these elements are excellent in easiness to make and use.

In order to obtain excellent characteristics of the PDP, the material powder used for the protective layer of the discharge electrode for display contains at least one element selected from atomic number 71 or less in the groups I to IIIa of the periodic table of elements. Compounds are included. The material powder is typically an oxide containing these elements (hereinafter referred to as a specific oxide), but may be a compound in the form of being converted into a specific oxide in the process. If these elements are included, they may be composites with other elements. However, the higher the ratio of the above elements, the γ
Tends to increase. Also IIa and IIIII
Group Ia is preferable because even a single element can form a stable oxide. Since it is difficult to obtain a stable oxide with the group Ia element alone, it is preferable to combine it with another element, and particularly, a composite oxide with the group IIa or group IIIa element is preferable. MgO is considered to be the most excellent in the comprehensive characteristic evaluation. However, the individual composition selection of the protective layer is determined from the results of measured discharge characteristics (discharge sustaining voltage and stability, operation margin, etc.) that form discharge tubes of the same shape.

The element A of the chemical formula AX used in the present invention is preferably an element capable of forming an oxide dielectric having a melting point of 1000 ° C. or higher when thermally decomposed. If the melting point of the produced oxide is 1000 ° C. or lower, it is easy to melt in the melt and the stable discharge characteristics are maintained, which is not preferable.

Next, the characteristic feature of the powder material used in the dielectric composition of the present invention is that it has a fixing and dense smoothing action which is a function of the low melting point glass. For this reason, it is essential to include a component that melts during the protective layer forming step.
The appropriate melting temperature is determined by the constituent material of the PDP and the process temperature as described below.

When soda-lime glass for windows is used as the substrate, the maximum temperature at which glass deformation is negligible is about 650 ° C. When the heat resistance of the adherend substrate is high, a coating material having a higher melting point can be used. However, the higher the temperature, the greater the unnecessary reaction with the adhered substrate such as the electrode and the greater the economic burden. Usually, it is sufficient to set 850 ° C. to the maximum temperature, preferably 650 ° C. or lower.

On the contrary, it is preferable that the melting point of the dielectric material is higher because of the requirement that it is not deformed in the subsequent process of assembling the PDP. As a main post-process, there is usually a heating and evacuation process at 350 ° C
This removes the adsorbed impure gas from the PDP constituent members. Further, in the sealing step using the seal glass, the working temperature varies depending on the glass used, but generally 450 to 5
50 ° C is adopted. Therefore, the melting point of the electrode coating material is 350 ° C. or higher, preferably 450 ° C. or higher.
However, as will be described later, thermal decomposition of the melt produces a high-melting point substance, which improves heat resistance. In addition, in a mixed system with a small amount of melt, the deformation of the coating layer can be reduced even at the melting temperature or higher. Therefore, it is not necessary to set the minimum melting temperature of the starting material.

The powder material used in the dielectric composition of the present invention contains at least one component represented by the chemical formula AX represented by the following 1) or 2) or a thermal decomposition product having a melting point of 850 ° C. or lower.

1) A in the chemical formula is an element capable of forming an oxide dielectric having a melting point of 1000 ° C. or higher.

2) X in the chemical formula is F, Cl, Br, I,
It is composed of at least one group selected from each group of SO _{4 ,} NO _{3 ,} CO _{3 ,} CN and OH.

Since the thermal decomposition reaction is complicated and has not been accurately identified, the above-mentioned meltable substances are collectively referred to as AX and the like unless otherwise specified. However, if AX or the like is selected, a single component or two components can be used. A mixture having a melting point of 850 ° C. or lower can be easily selected by the above mixing.

Al and S are preferable as the A element.
Examples of i, Zr, etc., and elements forming the specific oxide are given.
These elements form an oxide having a high melting point and a high insulating property. Not preferable are In, Sn, Zn and R.
u, Mo, Rh, W, Re and the like, oxides of these elements have high conductivity. For transition metal elements such as Ti, V, Mn, Fe, Ni, and Co, oxides having high insulating properties also exist, but the insulating properties are likely to change due to valence variation, which is not preferable.
Further, elements such as B, Pb, and Bi are not preferable because the melting point of the oxide is low. Other complex oxides, which are not exemplified, can be selected in consideration of the high melting point, the high insulating property and the stability thereof as described above. High melting point is a measure of stability,
It refers to a substance that does not solidify the melt by reacting with the melt in a short time, and may be twice the melting temperature of AX or the like. For example, A
If the melting temperature of X etc. is 850 ° C, the melting point is 1700 ° C.
The above oxides can be used safely. The higher the insulating property is, the more preferable, but it is common sense that the volume resistance at room temperature is 10 ¹³ Ω · cm or more for use as a dielectric.

The protective layer in which the specific oxide is dispersed in the AX or the like shows excellent characteristics, and the AX or the like is 70 vol% or less.
Even if it is more than the above, it is possible to obtain the one without characteristic deterioration. This is a clear difference from the prior art that the characteristics of the protective layer deteriorate when the specific oxide is mixed with 10 vol% of low melting point glass.

As the material powder used for the protective layer, the above A
It is possible to mix dielectric powders that do not melt except X or the like. For example, a specific oxide essential to the present invention or a high melting point substance for improving heat resistance, which is a periodic table I to IIIa.
An oxide containing at least one element selected from atomic number 71 or less in the group may be further added. There is a required amount of melt to form a dense and smooth protective layer and adhere it to the substrate. With only powder that does not melt, the packing density is 50 vo
This is because it is difficult to set l% or more, and the fixing force is also small. To increase the operating margin of PDP, porosity is 30
A protective layer having a vol% or less is preferable, and more preferably 10
vol% or less. For this reason, 30 vol% or more, preferably 40 vol% or more of the protective layer must be filled with the melt. In general, the packing density of the powder is smaller and the wetting with the melt is not perfect. In addition, the volume of the melt decreases due to evaporation, thermal decomposition, etc. during the process. Taking these into consideration, it is desirable that 50 vol% or more of the protective layer material is melted. The adherence of the protective layer depends on the type of powder, but the larger the melting amount, the better. Generally, at 25 vol% or more, preferably at 50 vol% or more, good workability of PDP assembly can be obtained.

The A element of the chemical formula AX used in the present invention is preferably an element capable of forming an oxide dielectric having a melting point of 1000 ° C. or higher when thermally decomposed as described above.

As described above, it is particularly preferable that the element A can form a specific oxide.

The first reason is that γ such as AX is large. If γ of AX or the like is larger than that of the specific oxide, γ of the entire protective layer can be increased. Since the amount of the specific oxide added can be reduced even when γ is about the same, the porosity of the protective layer can be easily reduced, and the adhesion is strong. Even if such AX or the like does not melt, it can be used as a dispersant. However, since AX and the like are generally not as stable as oxides, it is still necessary to disperse the specific oxide.

The second reason is that AX can be thermally decomposed to form a specific oxide.

For example, when X is each group of SO ₄ , NO ₃ , CO ₃ and OH, each group is eliminated to produce a specific oxide, and even in the case of each group of F, Cl, Br and I. In the oxygen-containing atmosphere, the specific oxide is similarly produced. When the specific oxide powder and the melt are mixed, the surface of the protective layer is likely to be coated with the melt substance. If the melt-forming material is unstable or γ is not large, the surface characteristics are disadvantageous to the important discharge characteristics. However, if the specific oxide is decomposed and produced using the above AX or the like as a melt, the specific oxide is surely produced on the surface.

The required amount of the specific oxide depends on the production method.
When the specific oxide is not generated from AX or the like and only the specific oxide powder is added, the required amount of the specific oxide is large for the reason described above. This is to prevent the specific oxide from being completely covered with AX or the like. Therefore, at this time, the density, smoothness and adhesion of the protective layer are likely to be sacrificed. The amount of the specific oxide powder added varies depending on the powder shape and particle size of the specific oxide, etc.
% Or more, preferably 50 vol% or more.

When the specific oxide is produced only by decomposition of AX or the like, the addition amount of the specific oxide may be small. This is because the thermal decomposition of AX or the like starts from the melting surface and fine crystals are uniformly generated. Since the thermal decomposition reaction of AX and the like is complicated, it is difficult to accurately quantify the thermal decomposition product. Therefore, the production amount of the specific oxide is expressed by an X-ray diffraction peak. In this case, good discharge characteristics can be obtained if the specific oxide is observed in the X-ray diffraction peak of the protective layer. From this result, if the formation of the specific oxide is recognized in the X-ray diffraction peak, the amount of the specific oxide powder to be added may be 30 vol% or less. If the integrated value of the diffraction line peak is larger than that of the specific oxide, it may be smaller. Also, when the specific oxide is produced by both of the above methods, the addition amount of the specific oxide may be similarly small.

The third reason is that it is easy to form a transparent protective layer.

The AX and the specific oxide used in the present invention are colorless and transparent. However, it is not always transparent in a mixed system. The reason why the film becomes opaque is that there are phases with different refractive indices. For example, the presence of voids in the membrane should be avoided, preferably at least 5 vol% or less. It is often difficult to match the refractive index, and even if the refractive index is similar, the crystal grain boundary often becomes a reflective phase, and thus tends to become opaque. In such a case, the film can be made transparent by setting the crystal particle size to be half the wavelength of light or less. If only AX or the like is used as a protective material and a part of this is decomposed to generate a specific oxide, a protective layer having a light transmittance of 60% or more can be obtained.
The reason for this is that since the whole is melted, there are no voids, and the crystal diameter and amount of the specific oxide can be controlled small. If an amorphous type is selected as AX or the like that does not become an oxide, there is no problem in transparency, but even a crystalline type has high transparency. It is presumed that this is because AX and the like have strong ionicity and are soft, so that the crystal grain boundaries are easily relaxed. Needless to say, the A element such as AX that does not become an oxide may not be a specific oxide. As described in the related art, the light transmittance of 60
% Or more of the protective layer is useful for a reflection type PDP which can obtain high brightness.

When an oxide is formed by thermal decomposition, all A
It is not very preferable to decompose X and the like into oxides. Since the oxide used in the present invention has no plasticity at 850 ° C. or lower,
This is because the protective layer cannot be rearranged and the volume reduction caused by decomposition cannot be filled. However, the porosity of the protective layer is 30%
If the filling rate of the powder and the decomposition reduction rate of AX and the like as described below can be sufficiently used. For example, if 50 vol% of a powder having a filling rate of 50% and 50 vol% of AX having a decomposition reduction rate of 50 vol% are mixed, a protective layer having a porosity of 25% can be obtained even if AX is completely decomposed into an oxide. To be The amount of oxides generated by decomposition can be roughly estimated by the porosity, but it may be set in consideration of the discharge characteristics and the light transmittance of the protective layer.

When the thermal decomposition reaction occurs, the decomposition gas may become a problem. Gas toxicity and corrosiveness. NO ₃ , CO ₃ and O can be used as the X group which causes less decomposition gas.
H and the like are preferable. Considering the selectivity of the melting point and the controllability of the decomposition reaction, it is most preferable to contain a NO ₃ group.

AX and the like are preferably compound compounds rather than single compounds. This is because the degree of freedom in selection such as melting temperature and thermal expansion is increased. With a single compound, thermal decomposition occurs rapidly at a specific temperature and is difficult to control, and the protective layer is likely to be deformed or the porosity tends to increase. Sublimation compounds cannot prevent sublimation. In addition, since large crystals are likely to be generated when cooled and solidified after melting, surface irregularities also become large.

Regarding the thermal expansion, in a PDP in which various thermal processes are adopted, cracks occur when the difference in thermal expansion between the substrate and the protective layer is large, and peeling occurs in extreme cases. However, in the case of the present invention, the adhesive force of AX or the like involved in the adhesion is relatively small, and the ionicity of AX or the like is strong and soft, so the stress due to the difference in thermal expansion is relaxed and small. Therefore, even if the thickness is about 50 μm, the degree of freedom of thermal expansion is very large in the protective layer of the present invention.

The chemical formula AX used in the dielectric composition of the present invention includes one that changes into AX by heating. For example, a substance containing water of crystallization or a substance in which NaHCO ₃ is thermally decomposed into Na ₂ CO ₃ . Those containing water of crystallization are usually dehydrated up to about 350 ° C. A water component that exists at a temperature higher than this is also called structural water and has a complicated structure containing an OH group. Therefore, it is obvious that these compounds are also included in the present invention.

The dielectric composition of the present invention has a general structure except for the above-mentioned dielectric material, and has workability suitable for film formation and patterning.

The dielectric powder generally has an average particle size of 30 μm or less. The dielectric can be dissolved in a liquid vehicle with which it is mixed, but it is not preferable because the suitability of the liquid vehicle (solubility of resin, etc.) often changes.

Liquid vehicles have good workability (eg printability)
Most commonly, the polymer component is dissolved in a solvent. Examples of the polymer include celluloses such as methyl, ethyl and nitro, resins such as acryl and epoxy, and those in which an inorganic salt is dissolved in water to be in a sol or gel state. Examples of the solvent include pine oil, butyl carbitol, butyl carbitol acetate, cellosolve, water and various glycols.

The ratio of the dielectric powder to be mixed is determined in consideration of workability. For thick film printing, which is the most economical, 100 parts by weight of powder and 25 to 70 parts by weight of liquid vehicle. If it is less than 25 parts by weight, the viscosity becomes too high and it is not suitable for printing. If it exceeds 70 parts by weight, it becomes difficult to maintain the shape due to insufficient viscosity, and even if it can be retained, it is difficult to secure the thickness. If the above dielectric composition is used, 20 μm is obtained by applying the thick film technology.
A film of about m can be easily obtained. Therefore, it is possible to easily form the coating dielectric with only the protective layer material without forming the base glass layer.

Although the present invention is characterized by the dielectric composition for forming the protective material for covering the discharge electrode, the protective layer formed from this can be easily formed by a technique other than the thick film technique, for example, a thin film technique. It will be clear what will be achieved. Further, the applied gas discharge tube is the same as the conventional one except for the protective layer material, and therefore other general construction methods, materials, formation techniques and the like can be used.

Hereinafter, the present invention will be described more specifically by way of examples.

[0058]

EXAMPLES Examples 1 to 16 and Comparative Examples 1 to 4 Soda lime glass was used for the front plate FG and the back plate BP, and the line-shaped display discharge electrodes Sx and Sy were used for the front glass plate.
Was formed of an ITO film. Further, a base glass layer (not shown) is further coated with a glass powder (P by Nippon Electric Glass Co., Ltd.).
L3232), a coated dielectric DL made of various materials was formed as a surface protection layer. The thickness of this coated dielectric was constant at about 40 μm for the base glass layer + the protective layer. To form the protective layer, the total of 100 powders shown in Table 1 should be used.
10 parts by weight of butyl carbitol acetate
Vehicle containing 30% t% ethyl cellulose dissolved
An ink in which 0 part by weight was kneaded was used. The ink viscosity and the number of times of printing were adjusted, and firing was performed in the air at a firing temperature of 580 ° C. for 10 minutes (Examples 1 to 16 and Comparative Examples 3 and 4), except where otherwise specified, to obtain a predetermined thickness.

In Comparative Examples 1 and 2, the firing temperature was 300.
It was baked at 10 ° C. for 10 minutes so as to have a predetermined thickness.

Next, on the rear glass plate BP, a linear write electrode W was formed of an ITO film in a direction orthogonal to the linear display discharge electrodes Sx and Sy on the front glass plate FG. Further, the surface thereof was coated with phosphor PH powder. A partition wall (not shown), which is a spacer between the front plate and the rear plate, was formed on this in parallel with the write electrode.

The peripheral portions of the front plate and the back plate thus formed, which are opposed to each other, are sealed with seal glass, and the exhaust holes formed in the back plate and the tip tube connected thereto are used to
After exhausting the inside of the container, Xe was introduced as a discharge gas, and the tip tube was tipped off to form a PDP.

The characteristics of the PDP thus formed were measured. The obtained operation margins (measured at the number of cells of 128 × 128 at the initial stage and after 5000 hr respectively) are shown in Tables 1 and 2. The constituent members of the PDP, the shape, the gas conditions, the driving conditions, and the like were the same, and the discharge voltage was set to be almost the same value.

[0063]

[Table 1]

[0064]

[Table 2] As is clear from the results of Tables 1 and 2, Examples 1 to 1
3 and Comparative Examples 1 and 2 have Mg (NO ₃ ) ₂ · as AX.
The ratio of 6H ₂ O and KNO ₃ was changed. Mg
(NO _{3) 2} · 6H ₂ after O firing in many embodiments 1 Mg
Since O is generated, margin fluctuation is small.

On the other hand, in Comparative Examples 1 and 2, MgO was not produced, and the margin disappeared within several hours. Examples 2 and 3 are obtained by subjecting the protective layers of Comparative Examples 1 and 2 to oxygen plasma treatment, and MgO is generated on the surface, and therefore show the same good characteristics as Example 1. Examples 4 and 5 correspond to Example 1
This is an example of using a powder obtained by heat-treating the powder material in advance at 290 ° C. and 420 ° C., that is, a thermally decomposed product (intermediate decomposition product). In Example 4, about 5H ₂ O of Mg (NO ₃ ) ₂ .6H ₂ O was decomposed and scattered, and in Example 5, further decomposition progressed and a part of the remaining H ₂ O and NO ₃ salt. Is being disassembled. Of course, KNO ₃ may have evaporated or decomposed, but in any case, it has a complicated composition. However, since it is sufficiently melted by firing at 580 ° C., the porosity of the protective layer is small and the transparency is good. Since these powders have lower hygroscopicity than Example 1, a stable composition can be obtained.

In Examples 6 and 7, Mg was added to the compositions of Comparative Examples 1 and 2.
50% by volume of O was added, and in Examples 8 and 9, La ₂ O ₃ .TiO ₂ was added instead of MgO of Examples 6 and 7.

Comparative Examples 3 and 4 use only powders of MgO and Mg (OH) _{2 which} are not melted as the protective material, and have a small operation margin. Example 1 compared to these
0 is the AX Mg (OH) ₂ and Mg (NO _{3) 2} · 6
Although a protective layer was formed by decomposing all H ₂ O into MgO, the protective layer has good characteristics because of its large density and smooth surface. In addition, Examples 6 to 10 and Comparative Example 3
Since the powder-added protective layers of # 4 and # 4 have low transparency,
The DP configuration was used.

In Examples 11 to 15, instead of KNO ₃ of Example 1, CsNO ₃ , RbNO ₃ , Al (NO ₃ ) ₃ ,
It uses KCl and MgF. In Example 16, the protective layer was formed only by the composition of Example 1 without using the base glass layer.

As is clear from the results of the above Examples and Comparative Examples, the protective layer of this Example has a large operating margin and good stability. Although the above examples demonstrate the limited materials, it will be clear that there are many combinations that satisfy the gist of the present invention due to chemical similarity. It will be fully understood from the examples that the proper selection varies depending on the structure of the discharge tube, the material, the process used, etc., and can be determined experimentally.

[0070]

From the above examples and explanations, if the dielectric composition of the present invention is used for the protective layer for coating the discharge electrode of a gas discharge tube, the following effects can be obtained, and therefore the characteristics are good. Gas discharge tube can be obtained at low cost.

1) A protective layer equivalent to or more than a protective layer obtained by applying a thin film technique which is said to have excellent characteristics can be obtained by applying a simple thick film technique.

2) As compared with the protective layer obtained by applying the conventional thick film technique, a protective layer excellent in operation margin, stability, transparency and the like can be obtained.

[Brief description of drawings]

FIG. 1 is a partial schematic sectional view showing a gas discharge tube of the present invention.

[Explanation of symbols]

FG: front glass plate, BP: rear plate, Sx, Sy: display discharge electrode, W: writing electrode, DL: coated dielectric, P
H: phosphor.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tatsumasa Yokoi, 1-3-1, Noritake Shinmachi, Nishi-ku, Nagoya-shi, Aichi Noritake Company Limited Limited 36 (72) Inventor Naoya Kikuchi 3-chome, Noritake-shinmachi, Nishi-ku, Nagoya, Aichi 1-36 Noritake Company Limited (72) Inventor Masaaki Ito 3-36 Noritake Shinmachi, Nishi-ku, Nagoya-shi Aichi Prefecture Noritake Company Limited

Claims (6)

[Claims] 1. A discharge electrode covered with a dielectric is formed in a container containing a discharge gas, and a protective layer on the discharge surface is formed by chemical formula AX represented by the following 1) or 2) or its thermal decomposition. And a dielectric containing at least one component having a melting point of 850 ° C. or less, and an oxide containing at least one element selected from atomic number 71 or less in Group I to IIIa of the Periodic Table of Elements, and having a porosity A gas discharge tube characterized by being formed as a film of 30% or less. 1) A in the chemical formula is an element capable of forming a dielectric oxide having a melting point of 1000 ° C. or higher. 2) X in the chemical formula is F, Cl, Br, I, SO _{4 ,} NO
It is composed of at least one group selected from each group of _{3 ,} CO _{3 ,} CN and OH. 2. The gas discharge tube according to claim 1, wherein the visible light transmittance of the protective layer is 60% or more, and the electrode and the covering dielectric material are adhered and formed on the inner surface of the display glass constituting the discharge gas container. 3. The gas discharge tube according to claim 1, wherein all of the chemical formula AX is decomposed into oxides, and the protective layer is formed of dielectric powder having a melting point of 1000 ° C. or higher. 4. A dielectric composition in which 100 parts by weight of a dielectric powder and 25 to 70 parts by weight of a liquid vehicle are kneaded, and the powder has an atomic number of 71 in Group I to IIIa of the Periodic Table of Elements. At least one elemental compound selected from the following is included, and the chemical formula A represented by the following 1) or 2)
A dielectric composition comprising at least one component of X or a thermal decomposition product thereof having a melting point of 850 ° C. or lower. 1) A in the chemical formula is an element that can form an oxide dielectric having a melting point of 1000 ° C. or higher. 2) X in the chemical formula is F, Cl, Br, I, SO _{4 ,} NO
It is composed of at least one group selected from each group of _{3 ,} CO _{3 ,} CN and OH. 5. The dielectric composition according to claim 4, wherein A in the chemical formula contains at least one element selected from atomic numbers 71 and less in the groups I to IIIa of the periodic table of elements. 6. The powder according to claim 4 or 5, wherein all powders have the chemical formula AX or a thermal decomposition product thereof at 850 ° C.
An oxide containing at least one element selected from the atomic number 71 or less in the group I to IIIa of the Periodic Table of Elements is decomposed and produced from the melt, which is composed of components having the following melting points, and is visible in the deposited film. A dielectric composition capable of having a light transmittance of 60% or more.