JP2000067810A - Discharge lamp electrode and discharge lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To extend the service life of a hot cathode fluorescent discharge lamp. SOLUTION: This discharge lamp electrode comprises a cylindrical container 1 having one end closed and an electron emission material 2 received in the container 1, and the container 1 and the electron emission material 2 has a main constituent including, a composite oxide containing nitrogen and/or a composite oxide containing, as metal element constituents, a first constituent comprising at least one kind of Ba, Sr and Ca, a second constituent comprising at least one kind of Zr and Ti, and a third constituent comprising at least one kind of Ta and Nb. In the discharge lamp electrode, the content of the first constituent in the exposed surface of the electron emission material 2 viewed from an opening side of the container 1 is higher than that in the end face on the opening side of the container 1. The electron emission material 2 is a porous body having an air gap rate of 45-80%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp electrode used for a backlight of a liquid crystal display device, a compact fluorescent lamp, a small fluorescent discharge lamp used for a reading light source such as a facsimile or a scanner, and this electrode. With a discharge lamp.

[0002]

2. Description of the Related Art In recent years, social demands for energy saving and resource saving have been increasing, and in response to this, energy saving of displays and light sources for general lighting has been actively promoted. For example, replacing a CRT with a liquid crystal display that consumes less energy, or replacing an incandescent light bulb with
Replacement with bulb-type fluorescent lamps, which have higher energy efficiency and longer life, is rapidly progressing. Along with this, the use of thin-tube fluorescent discharge lamps for a backlight light source of a liquid crystal display and a bulb-type fluorescent lamp is rapidly advancing.

[0003] Generally, fluorescent discharge lamps are classified into hot cathode fluorescent discharge lamps utilizing arc discharge due to thermionic emission, and cold cathode fluorescent discharge lamps utilizing glow discharge utilizing secondary electron emission. The hot cathode fluorescent discharge lamp has a smaller cathode drop voltage than the cold cathode fluorescent discharge lamp, and therefore has a higher luminous efficiency with respect to electric power. Further, the hot cathode fluorescent discharge lamp can increase the current density by utilizing thermionic emission, so that it is easy to increase the brightness as compared with the cold cathode fluorescent discharge lamp. Therefore, hot cathode fluorescent lamps
It is suitable for a light source that requires a large amount of luminous flux, such as a large-area backlight for a liquid crystal display, a bulb-type fluorescent lamp, and a reading light source such as a facsimile or a scanner.

[0004] As a conventional electrode for a hot cathode fluorescent discharge lamp, for example, a fluorescent discharge lamp electrode in which a tungsten coil is coated with an alkaline earth metal containing a part of a transition metal and barium is known (Japanese Patent Application Laid-Open No. H10-163,837). No. 59-75553). However, since the electrode described in the publication requires preheating to start thermionic emission, it is difficult to make the electrode as thin as a cold cathode fluorescent discharge lamp. Therefore, thin,
It is difficult to use it for a liquid crystal display for a notebook personal computer that requires light weight, and it is also unsuitable for miniaturizing a compact fluorescent lamp.

On the other hand, JP-A-4-73858 discloses an electrode having a structure which does not require preheating to form a thin tube. This electrode is obtained by depositing an emitter material composed of an oxide of barium, calcium, and strontium on a double coil of tungsten. But,
In a discharge lamp using an electrode having this structure, so-called ion sputtering, in which Hg ions or rare gas ions generated during discharge collide with the electrode and scatter electron-emitting substances, occurs remarkably. If the ion sputtering is remarkable, the electron emission material is depleted during the discharge, and a stable arc discharge cannot be maintained for a long time. Also,
The phenomenon in which the inner wall of the glass tube of the lamp is blackened by the scattered electron-emitting substances (tube wall blackening) occurs, and the luminous flux maintenance ratio is reduced at an early stage.

Further, US Pat. No. 2,686,274 describes a rod-shaped electrode obtained by reducing a ceramic such as Ba ₂ TiO ₄ into a semiconductor. Electrodes have problems that they are susceptible to thermal shock, easily deteriorated by sputtering with Hg ions or rare gas ions, and have low current density.

With respect to such a conventional electrode for a hot cathode fluorescent discharge lamp, the present inventors have proposed an electrode having a structure in which a ceramic semiconductor is housed in a cylindrical container having one end open and one end closed. Various improvements have been made to this electrode and to a discharge lamp using this electrode (Japanese Patent Publication No. 6-103627, Japanese Patent Application Laid-Open No. 1-65764, Japanese Patent Application Laid-Open No. 2-186550, Japanese Patent Application Laid-Open 2-18
No. 6527, JP-A-4-43546, JP-A-6-267404, JP-A-9-129117, JP-A-10-12189, JP-A-6-302
298, JP-A-7-142031, JP-A-7-262983, and JP-A-10-3879. The electrode of this structure has a feature that it does not require preheating and can be made into a thin tube, and has a long life because deterioration due to ion sputtering or evaporation is suppressed. However, in order to eliminate the need to replace the backlight of a liquid crystal display, it is necessary to make the life of the electrodes longer than the life of the device on which the display is mounted, and for this purpose, the life of the electrodes needs to be further improved There is. Further, in the fluorescent discharge lamp, if the on / off operation is frequently repeated, the electrode deteriorates remarkably, and the life is extremely shortened.
It is necessary to suppress shortening of the service life due to repeated turning off.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to extend the life of a hot cathode fluorescent lamp.

[0009]

The above object is achieved by the following (1).
To (8). (1) A first component having a cylindrical container having an open end, and an electron-emitting material contained in the container, wherein the container and the electron-emitting material are at least one of Ba, Sr, and Ca. And a composite oxide containing at least one of Zr and Ti and a third component consisting of at least one of Ta and Nb as a metal element component and / or a composite oxide containing nitrogen as a main component. A discharge lamp electrode wherein the content of the first component on the exposed surface of the electron-emitting material as viewed from the opening side of the container is higher than the content of the first component on the end surface on the opening side of the container. (2) A first component having a cylindrical container having an open end, and an electron-emitting material contained in the container, wherein the container and the electron-emitting material are made of at least one of Ba, Sr, and Ca. And a composite oxide containing at least one of Zr and Ti and a third component consisting of at least one of Ta and Nb as a metal element component and / or a composite oxide containing nitrogen as a main component. An electrode for a discharge lamp, wherein the electron-emitting material is a porous body having a porosity of 45 to 80%. (3) The discharge lamp electrode according to the above (1) or (2), wherein the density of the container is 60% or more of the theoretical density. (4) The discharge lamp electrode according to any of (1) to (3) above, wherein the discharge surface has an average radius of curvature of 10 to 150 μm. (5) Carbide containing at least one of Ta, Nb and Ti and / or carbide on the exposed surface of the electron emission material viewed from the opening side of the container and the end surface on the opening side of the container and the outer surface and / or the bottom surface of the container. The above (1) where a nitride exists
The electrode for a discharge lamp according to any one of (1) to (4). (6) When the first component is represented by M ^I , the second component is represented by M ^II , and the third component is represented by M ^III , the container and the electron-emitting material are M ^I M ^II O ₃ type crystal, M ^I ₅ M ^III ₄ O ₁₅ type crystal, M ^I
₇ M ^III ₆ O ₂₂ type crystal, M ^I M ^III O ₂ N type crystal and M ^I ₆
The discharge lamp electrode according to any one of the above (1) to (5), comprising at least one kind of crystal selected from M ^II M ^III ₄ O ₁₈ type crystals. (7) In the crystal, a part of M ^III is replaced by M ^II, the discharge lamp electrode of the (6) a part of M ^II is replaced by M ^III. (8) A discharge lamp having the discharge lamp electrode according to any one of (1) to (7).

The present inventors have found that ion sputtering of electrodes in a hot cathode fluorescent discharge lamp occurs remarkably during glow discharge. Then, it has been found that by applying the present invention, it is possible to make a quick transition from glow discharge to arc discharge, and the present invention has been achieved.

Specifically, by setting the content of the first component on the exposed surface of the electron-emitting material higher than the content of the first component on the end face on the opening side of the container, in other words, by setting the content of the opening of the container. By setting the content of the first component low on the side end face, the conductivity of the end face on the opening side of the container is increased, and discharge is easily generated on the exposed surface of the electron emission material. Therefore, the container functions sufficiently as a conductive path, and the occurrence of unstable discharge at the end face on the opening side of the container is suppressed, and a stable arc spot can be quickly formed on the exposed surface of the electron emission material. Therefore, a quick transition from glow discharge to arc discharge becomes possible.

If the electron-emitting material is made of a porous material having a porosity of 45% or more, the thermal conductivity in the electron-emitting material becomes critically low, so that the temperature partially rises and the arc is quickly released from the glow discharge. It is possible to shift to discharge.
On the other hand, if the porosity is too high, the electron-emitting material will fall off during discharge and the life will be shortened. However, if the porosity is suppressed to 80% or less, the dropout of the electron-emitting material will be suppressed. There is no hindrance to longer life due to shortening.

As described above, according to the present invention, it is possible to remarkably suppress the deterioration of the electrode during lighting, and it is particularly effective when the number of times of glow discharge increases due to frequent repetition of ON / OFF.

[0014]

DETAILED DESCRIPTION OF THE INVENTION The configuration example of the discharge lamp electrode of the discharge lamp electrodes present invention, shown in FIG. The discharge lamp electrode includes a cylindrical container 1 having one end opened, and an electron-emitting material 2 accommodated in the container 1. In the discharge lamp tube, ions such as Hg ions generated by the discharge fly from the direction of the counter electrode and collide with the electrode. At this time, the ions are blocked by the container 1 and collide with the electron emission material 2. Will be reduced. The container 1 functions as a conductive path for supplying a current to the electron-emitting material 2 while preventing the electron-emitting material 2 from being sputtered by ions.

In the present invention, each of the container 1 and the electron-emitting material 2 contains a composite oxide or a composite oxide containing nitrogen as a main component, and at least one of Ba, Sr and Ca as a metal element component. A second component composed of at least one of Zr and Ti, and a third component composed of at least one of Ta and Nb. First
The compound containing the component is a low work function electron emitting component. The second component is a component necessary for increasing the melting point of the electron-emitting material. Further, Ti and the third component of the second component serve as a supply source of a compound for constituting a sputtering preventing layer described later. When the container 1 is made of the same material as the electron emission material 2, it is possible to electrically and mechanically firmly join them.

The first component, the second component, and the third component constitute a composite oxide or a composite oxide containing nitrogen.
When the first component is represented by M ^I , the second component is represented by M ^II , and the third component is represented by M ^III , the electron-emitting material and the container are M ^I M ^II O ₃
Type _{^{crystals, M I 5 M III 4 O}} 15 type _{^{crystal, M I 7 M III 6 O}} 22 type crystal, M ^I M ^III O ₂ N type crystals and _{^{M I 6 M II M III 4}} O 18
It is preferable to include at least one crystal selected from the type crystals. In these crystals, a part of M ^III is sometimes substituted by M ^II, part of M ^II is sometimes are replaced by M ^III. The presence of these crystals can be confirmed by X-ray diffraction. In addition, the fact that a part of the element is replaced by another element means that X
It can be confirmed by the shift of the peak in the line diffraction.

In the container and the electron-emitting material, the atomic ratio of the first component is X, the atomic ratio of the second component is Y, and the atomic ratio of the third component is the total of the first component, the second component and the third component. Where Z is preferably 0.8 ≦ X / (Y + Z) ≦ 2.0, 0.05 ≦ Y ≦ 0.6, 0.4 ≦ Z ≦ 0.95, more preferably 0.8 ≤X / (Y + Z) ≤1.6, 0.1≤Y≤0.4, 0.6≤Z≤0.9. If X / (Y + Z) is too small, the first component will be depleted early due to discharge. On the other hand, X / (Y +
When Z) is too large, evaporation and scattering of the electron-emitting material are apt to occur during discharge, so that the lamp tube blackening becomes severe and the lamp brightness is reduced. If Y is too small, the melting point of the electron-emitting material will be low, and densification will easily proceed. Therefore, when firing in a reducing atmosphere to produce the electron-emitting material, the porosity of the electron-emitting material should be set to an appropriate value. Is difficult to keep. As a result, it becomes difficult to make the electron-emitting material porous, and it becomes difficult to maintain stable discharge. On the other hand, if Y is too large, the resistance of the electron-emitting material becomes too high, and it becomes difficult to maintain stable discharge.
If Z is too small, carbides and / or nitrides are less likely to be formed on the surface of the container and the surface of the electron-emitting material when the electron-emitting material is manufactured by firing in a reducing atmosphere.
As a result, the resistance to ion sputtering becomes insufficient. On the other hand, if Z is too large, evaporation and scattering of the container and the electron-emitting material become severe when firing in a reducing atmosphere to produce the electron-emitting material.

The electron emitting material is preferably a porous body. By using a porous material, the thermal conductivity can be lowered, and the temperature can be easily increased partially, so that it is easy to quickly shift from glow discharge to arc discharge, and to maintain stable arc discharge. Becomes easier.
When the electron-emitting material is a porous material, the porosity is preferably 45 to 80%, more preferably 55 to 75%. If the porosity is too low, a sufficient heat storage effect for thermionic emission cannot be obtained, and the transition from glow discharge to arc discharge becomes difficult, and the transition may not be possible. on the other hand,
If the porosity is too high, the electron-emitting material tends to fall off during the discharge, so that the life of the electrode is shortened.

As will be described later, the porous electron-emitting material can be obtained, for example, by firing a granulated calcined body without compression molding. The electron-emitting material manufactured by this method shows a property in which particles connected to other particles in at least one place are aggregated, and the shape of each particle is generally
It has irregular shape, spherical shape or needle shape. In such a porous electron-emitting material, one surface of a plurality of particles existing on the surface (exposed surface) on the container opening side becomes a discharge surface. The average radius of curvature of the discharge surface, that is, the average value of the radius of curvature of the particles present on the exposed surface is preferably 10 to 1
It is 50 μm, more preferably 20 to 100 μm. The radius of curvature when the particle has an irregular shape is the radius of a circumcircle of the particle. The radius of curvature of the discharge surface can be determined from a scanning electron micrograph of the cross section of the electrode. By setting the radius of curvature of the discharge surface within the above range, stable arc discharge can be easily maintained. If the arc discharge is not stable, voltage fluctuations and temperature fluctuations occur in the electrodes, and the electrode life is shortened. Setting the radius of curvature within the above range is particularly effective when the lamp current is 5 to 500 mA. Since the preferred average radius of curvature of the discharge surface decreases as the lamp current decreases, the specific average radius of curvature may be appropriately selected from the above range according to the lamp current. In addition, if the lamp current is 5 mA or more, it is generally sufficient for thermionic emission.
When the present invention is applied to a thin tube lamp of less than mm, the lamp current is generally 500 mA or less.

The shape of the container is not particularly limited as long as it has a cylindrical shape with one end opened, that is, a cylindrical shape having a bottom portion. The size of the container is not particularly limited and may be appropriately determined depending on the diameter of the lamp. However, since the electrode of the present invention is particularly suitable for a thin tube lamp, the maximum diameter of the container is preferably 1 to 5 mm. The length of the container is preferably 0.5 to 5 mm. Further, the thickness of the side wall of the container is 0.2 to
It is preferably 1 mm. Also, the thickness of the container bottom is
It is preferably 0.2 to 2 mm.

The exposed surface of the electron emission material as viewed from the opening side of the container and the end surface on the opening side of the container are provided with Ta, Nb and Ti.
Preferably, a carbide and / or nitride containing at least one of the following is present. This carbide and / or nitride constitutes a sputtering prevention layer. This sputtering prevention layer is for protecting the electron-emitting material from the ions flying to the electrode. However, since the first component needs to be exposed on the exposed surface of the electron-emitting material, the sputtering prevention layer needs to be a porous film or a mesh film at least on the surface of the electron-emitting material. The thickness of the sputtering prevention layer is preferably about 3 to 10 μm. If the sputtering prevention layer is too thin, the effect of preventing ion sputtering tends to be insufficient. On the other hand, if the sputtering prevention layer is too thick, it becomes difficult to expose the electron emission material. Note that the carbide and / or nitride may be present not only at the exposed surface of the electron-emitting material, but also at positions other than the end surface on the opening side of the container.

Carbides and nitrides constituting the anti-sputtering layer have better conductivity than the material constituting the container. For example, by forming the above-mentioned sputtering prevention layer on the surface of the container, the specific resistance on the surface of the container is reduced to 10%.
Since it can be set to about 500 μΩcm, it becomes possible for the container to sufficiently function as a conductive path. The power supply to the discharge lamp electrode of the present invention is generally performed not only through the end face on the opening side of the container but also through the outer surface and / or the bottom surface of the container. Preferably, it is also present on the bottom surface.

Ta, N contained in the sputtering prevention layer
As the carbide and / or nitride containing at least one of b and Ti, in addition to the nitride or carbide of each element, a nitride or carbide containing a plurality of metal element components,
It may be a solid solution containing both carbon and nitrogen.

In the present invention, the content of the first component on the exposed surface of the electron emission material as viewed from the opening side of the container is higher than the content of the first component on the end surface on the opening side of the container. By providing the content of the first component with such a distribution, it is possible to quickly shift from glow discharge to arc discharge as described above.

Means for imparting such a distribution to the content of the first component is not particularly limited. For example, as a first means, there is a method of making the raw material composition of the container different from the raw material composition of the electron emission material. As a second means, there is a method in which the sputtering prevention layer has a different composition on the surface of the container and the surface of the electron emission material. As a third means, there is a method in which the aperture ratio of the sputtering prevention layer, which is a porous film or a network film, is different between the surface of the container and the surface of the electron-emitting material. In the case where the second means and the third means are used, the container and the electron-emitting material may have the same composition. Further, two or more of the first to third means may be used in combination.

The content of the first component on the exposed surface of the electron emission material as viewed from the opening side of the container and the content of the first component on the end surface on the opening side of the container are measured by electron beam probe microanalysis (EPMA). be able to. In the measurement by EPMA, an arbitrary count number for each element is set as a threshold, and the content of the first component may be compared assuming that the element exists in a region showing a count equal to or more than the threshold.

Next, a method for manufacturing an electrode for a discharge lamp will be described.

FIG. 2 shows a manufacturing process of the electrode. The basic flow of this manufacturing process is the same as that of a normal ceramic manufacturing process.

In this manufacturing process, first, starting materials are weighed and mixed according to the respective compositions of the container and the electron-emitting material (step S1). Compounds used as starting materials
Oxides or compounds that become oxides upon firing, for example,
Although carbonates and oxalates may be used, the compounds containing the first component usually include BaCO ₃ , SrCO ₃ and CaC
It is preferable to use O _3, and it is preferable to use ZrO ₂ and TiO ₂ for the compound containing the second component, and to use Ta ₂ O ₅ and Nb ₂ O ₅ for the compound containing the third component. preferable. For mixing, any of a ball mill method, a friction mill method, a coprecipitation method, and the like may be used.

Next, the mixed starting materials are calcined (step S2). The calcination conditions are not particularly limited, but usually 8
Heat treatment may be performed at 00 to 1300 ° C. for about 30 minutes to 5 hours. The calcination may be performed in a powder state or in a state in which the powder is formed.

Next, the obtained calcined body is pulverized by a ball mill method or an air current pulverization method (step S3) to obtain a calcined powder. Then, the calcined powder is granulated and granulated using an aqueous solution containing an organic binder such as polyvinyl alcohol, polyethylene glycol, and polyethylene oxide (step S4). The granulation means is not particularly limited, and for example, a spray drying method, an extrusion granulation method, a tumbling granulation method, a method using a mortar, a pestle, and the like can be used. The porosity in the electron-emitting material can be controlled by the amount of binder added during the granulation. The porosity can also be controlled by adding an organic polymer compound after granulation.

Next, the granules for a container are compression-molded to obtain a container-shaped compact (step S5). The pressure at this time is preferably 20 to 500 MPa. Then, the molded body is filled with granules for an electron emission material (step S6). It is preferable not to apply pressure during this filling. When pressure is applied, the necessary voids cannot be formed in the electron-emitting material regardless of the amount of binder or other polymer compound added during granulation, so that sufficient heat storage for thermionic emission The effect cannot be obtained. Therefore, preheating is required at the start of discharge. However, in order to prevent the electron emission material from falling off during discharge, it is preferable that the granules in the container are in contact with almost all of the other surrounding granules. If necessary, light pressure may be applied to such an extent that the granules are not deformed.

Next, the container and the granules filled therein are simultaneously reduced and fired (step S7) to obtain a sintered body (electrode).
Is obtained (step S8). The firing atmosphere is preferably a reducing gas such as hydrogen or carbon monoxide, an inert gas or a neutral gas such as argon or nitrogen, or an inert gas or a neutral gas containing a reducing gas. The density of the container after firing is preferably at least 60% of the theoretical density, particularly preferably at least 85%. By providing voids in the above-described range in the electron-emitting material and by densifying the container in this way, the effect of the present invention can be further improved, and, as described later, the container surface and the electron-emitting material surface Can produce different amounts of carbide and nitride.

In order to form carbide on the electrode surface, firing may be performed in an inert gas or neutral gas atmosphere containing a gas of a compound containing carbon. Further, by making the binder removed during firing insufficient, carbon can be supplied from the binder or the organic polymer compound to form a carbide. In addition, a firing furnace at least partially composed of carbon is used, or carbon powder or an organic polymer compound is put in the furnace, or the molded body is buried in carbon powder or an organic polymer compound and fired. Also by
The formation of carbides is possible. Further, two or more of the above means may be used in combination. Among these, a means for supplying carbon from the atmosphere, furnace material, and carbon powder in the furnace is preferable.
On the other hand, in order to form a nitride on the electrode surface, firing may be performed in a nitrogen atmosphere or an atmosphere containing a compound containing nitrogen, and by using together with the above carbide forming means, a carbide and a nitride are formed. It is possible to

Even when the container and the electron-emitting material have the same composition, the amount of carbide per unit area on the surface of the container is larger than the amount of carbide per unit area on the surface of the electron-emitting material. The same applies to the amount of nitride. This is because the compact as the container is pressurized and the granules as the electron emission material are not pressurized. The carbides and nitrides grow from the vicinity of the crystal grain boundaries of the container and the electron-emitting material to cover the crystal grains and form a film.
Since the growth proceeds more rapidly in a container that is pressure-formed, the area covered with carbide or nitride in the container is larger than that of the electron-emitting material. Therefore, even if both have the same composition, the content of the first component is higher in the container, and in the present invention, the container and the electron-emitting material can be made to have the same composition, and the production labor can be saved.

In the present invention, a sputtering prevention layer made of carbide and / or nitride can be formed on the electrode surface by using a vacuum deposition method, a sputtering method, or the like, in addition to the above means. When using these methods, the film formation may be stopped before the carbide and / or nitride completely covers the electrode surface.

The firing temperature is preferably from 1400 to 2000 ° C. If the firing temperature is too low, the formation reaction of the complex oxide or the complex oxide containing nitrogen does not proceed sufficiently,
At the time of lighting, the electron emission material tends to evaporate. On the other hand, if the firing temperature is too low, it is difficult to form carbides and nitrides by the above means. On the other hand, if the firing temperature is too high, the granules are melted, so that it is difficult to make the electron-emitting material a desirable property.

The discharge lamp 3 shows a configuration example of a discharge lamp using the electrode of the present invention.
It should be noted that only the vicinity of the pipe end is shown in FIG. This discharge lamp has a structure that can be made thin.

This discharge lamp is coated with a phosphor on its inner surface,
It has a hermetically sealed valve 9. A rare gas (at least one of He, Ne, Ar, Kr, and Xe) is sealed in the valve 9. The pressure of the rare gas in the valve 9 is preferably 1330 to 22600 Pa. By setting the pressure of the rare gas in this range, high brightness and long life can be achieved.

The lead wire 5 is inserted through the end of the valve 9. An enlarged lead wire portion 6 is formed at an end of the lead wire 5 present in the bulb 9. A conductive pipe 7 is connected to the lead wire enlarging portion 6. If the lead wire 5 can be connected to the conductive pipe 7 by other means, the lead wire enlarged portion 6 may not be provided. The conductive pipe 7 may be made of a material having a high electric conductivity, but a material that emits little gas in a vacuum.
For example, if Ni is used, the generation of gas containing impurities during the manufacture of the discharge lamp is suppressed, and stable discharge is possible.
preferable. However, the conductive pipe 7 may be made of ceramics. The container 1 is disposed in contact with the conductive pipe 7, and the electron emitting material 2 is filled in the container 1. A metal pipe 4 filled with a mercury dispenser material 3 is disposed between the container 1 and the lead wire enlarging portion 6 in the conductive pipe 7. The metal pipe 4
It is a tubular body having both ends opened, and may be made of a metal such as Ni. A slit-shaped opening (not shown) is formed in a portion of the conductive pipe 7 surrounding the metal pipe 4. Mercury in the mercury dispenser material 3 is converted into steam by high-frequency heating or the like on the metal pipe 4, passes between the metal pipe 4 and the lead wire enlarging portion 6 and between the metal pipe 4 and the container 1, and passes through the opening. Released into the discharge space 10. The opening is not limited to the slit shape and may have any shape as long as the opening can release mercury vapor and does not hinder the holding of the container 1. Further, it is not essential to provide the mercury dispenser material 3, and it may be configured to supply mercury into the bulb during the sealing process.

The electrode of the present invention is applicable not only to the discharge lamp having the structure shown in FIG. For example, the invention can be applied to various types of discharge lamps already proposed by the present inventors in the above publications.

[0042]

EXAMPLE 1 Ba was used as the first component, Zr was used as the second component, and the third component was used.
Ta is selected as a component, and Ba is used as a starting material for these components.
CO ₃ , ZrO ₂ and Ta ₂ O ₅ were prepared. For the electron-emitting material, the starting materials were weighed so that the ratio of Ba, Zr and Ta was Ba: Zr: Ta = 1.3: 0.2: 0.8, and wet-mixed for 20 hours by a ball mill. The starting materials were weighed so that Ba: Zr: Ta = 1.0: 0.5: 0.5 for the container, and mixed in the same manner.

Next, after the mixture was dried, the pressure was 10MPa.
Molded with a. The obtained molded body is placed in the air at 110
Calcination was performed at 0 ° C. for 2 hours. The obtained calcined product was wet-pulverized by a ball mill for 20 hours, dried, then added with an aqueous solution containing polyvinyl alcohol, and granulated using a mortar and pestle to granulate.

Next, the granules for a container were molded at a pressure of 200 MPa to obtain a cylindrical molded body having one end open and the other end closed (density: 3.6 g / cm ³ ). After filling the granules for an electron emission material into the molded body, the compact was fired at 1600 ° C. for 2 hours in a carbon furnace in a nitrogen gas flow atmosphere to obtain an electrode sample No. 104 shown in Table 1. The sample dimensions are
The outer diameter was 2.3 mm, the inner diameter (diameter of the granule container) was 1.7 mm, and the length was 1.7 mm. The density of the container was 6.8 g / cm ³ , which was 90% or more of the theoretical density. In this sample, the composition ratio of the metal element component in the electron emission material is Ba: Zr: Ta = 1.0: 0.2: 0.7, and the composition ratio of the metal element component in the container is Ba: Zr: Ta: Zr: Ta = 1.0: 0.5: 0.5 These composition ratios were measured by X-ray fluorescence analysis.

In Table 1, A is the content of the first component on the exposed surface of the electron-emitting material as viewed from the opening side of the container, and B is the content of the first component on the end surface on the opening side of the container. . Therefore, a sample with A / B> 1 is a sample of the present invention. In this case, the content rate is E
It is an abundance ratio (area ratio) of the first component measured by PMA. In the measurement by EPMA, the count number of the element to be measured was divided into seven levels, and it was determined that the element was present in a region where the count number was 3 or more. It should be noted that the setting of the number of division levels of the count number and the setting of the threshold level did not affect the determination as to whether or not A / B> 1 was satisfied.

Sample Nos. 101 to 103 shown in Table 1
Is an electrode sample manufactured in the same manner as in Sample No. 104 except that the composition of the electron-emitting material is different. The lower the ratio of Ba to all metal element components, the smaller the A / B. .

The EPMA image used for A / B measurement is shown in FIG.
To FIG. These EPMA images are obtained when the electrodes are viewed from the opening side of the container, and FIGS.
6 and 7 show the Ba distribution and the Ta distribution of Sample No. 102, respectively.
8 and 9 show sample No. a distributions, respectively.
101 shows a Ba distribution and a Ta distribution, respectively. In each of the figures, a region having a high brightness is a region having a high element concentration.

FIG. 4 shows a sample of the present invention, in which Ba on the surface of the container is slight, while Ba on the surface of the electron-emitting material is relatively large. FIG. 6 shows a comparative sample in which a relatively large amount of Ba exists on the surface of the container in addition to the surface of the electron-emitting material. FIG. 8 is also a comparative sample, in which the Ba on the surface of the container is small, but the Ba on the surface of the electron-emitting material is also small. On the other hand, T
Regarding the a distribution, it can be seen that Ta exists on both the surface of the container and the surface of the electron-emitting material in FIGS. 5, 7 and 9.

The porosity shown in Table 1 is the porosity of the electron-emitting material of each sample determined from a scanning electron micrograph of the cross section. The porosity was adjusted by filling an organic polymer compound (phenol resin powder) into the molded body in addition to the granules, and controlling the filling amount. Sample No.104
FIG. 10 shows a scanning electron micrograph of a cross section parallel to the axial direction. From the figure, it can be seen that the electron-emitting material has a needle shape and is integrated with the container. The average radius of curvature of the discharge surfaces of these samples was 10 to 50 μm.

Each of these electrode samples was used for the entire length of the bulb.
00mm, outer diameter 5mm, filling gas Ar, filling pressure 9.3kP
a, enclosure Hg, drive power frequency 30kHz, lamp current 3
Embedded in the discharge lamp of 0 mA, to measure the transition time T _GA from a glow discharge to an arc discharge. Table 1 shows the results.

[0051]

[Table 1]

From Table 1, it can be seen that if A / B> 1, the transition time _TGA is extremely short, 0.5 seconds or less.

Sample No. 104 was subjected to powder X-ray diffraction. Also, powder X-ray diffraction was performed on an electrode sample prepared in the same manner as in Sample No. 104 except that at least one of the composition of the electron-emitting material, the composition of the container, and the firing conditions was changed. As a result, in both the electron-emitting material and the container, Ba ₇ Ta ₆ O ₂₂ , Ba
At least one crystal of TaO ₂ N, Ba ₅ Ta ₄ O ₁₅ , Ba ₆ ZrTa ₄ O ₁₈ and BaZrO ₃ was confirmed.
In addition, from the shift of the peak position in the X-ray diffraction, it was presumed that a part of Ta was replaced by Zr and a part of Zr was replaced by Ta in each crystal. In the X-ray diffraction chart obtained by this measurement, the sample No.
11 and 12 show examples of the electron-emitting material 104 and the container, and FIGS. 13 to 15 show X-ray diffraction charts of electron-emitting materials of other samples. FIG. 15 is based on Cr-Kα, and the others are based on Cu-Kα.

In the above powder X-ray diffraction, the presence of carbides present on the container surface could not be clearly confirmed.
A disk-shaped sintered body was prepared under the same molding pressure and firing conditions, and X-ray diffraction was performed on the sintered body. FIG. 16 shows the results. FIG. 16 shows that a TaC film was formed on the surface of the sintered body. Further, observation with a scanning electron microscope revealed that this TaC film was a crystalline film. When the specific resistance of this TaC film was measured by a four-terminal method, it was 60 to 180 μΩcm. In addition, this Ta
The thickness of the C film was 3-5 μm.

Example 2 The above sample N was prepared except that the starting materials were blended such that the constituent ratio of the metal element components was Ba: Zr: Ta = 1.2: 0.3: 0.7.
An electrode sample was prepared in the same manner as in o.104. That is, in this sample, the mixing ratio of the starting materials was the same in the electron-emitting material and the container. The A / B of this sample was 2.0, which was included in the present invention.

Example 3 An electrode sample was prepared in the same manner as in Sample No. 104 of Example 1 except that the porosity was as shown in Table 2. For these samples, the transition time T
_GA was measured. In addition, the life was examined by measuring the duration of the arc discharge. Table 2 shows the results.

[0057]

[Table 2]

[0058] From Table 2, by the porosity and 45 to 80%, T _GA as short as 0.1 seconds, and 400
It can be seen that an arc discharge life of 0 hours or more can be obtained.
On the other hand, when the porosity is 40%, the _TGA is significantly increased to 10 seconds or more, and the life is significantly shortened. Also, it can be seen that the life is shortened even when the porosity is 85%. This is because the electron emission material was dropped during the lighting.

The A / B of the samples shown in Table 2 were all 5 or more.

Example 4 An electrode sample was prepared in the same manner as in Sample No. 104 of Table 2 except that the average radius of curvature of the discharge surface was as shown in Table 3. The average radius of curvature of the discharge surface was changed by classifying the granules after granulation with a mesh and controlling the particle size of the granules.

With respect to these, the stability of the arc spot was examined by setting the lamp current to the value shown in Table 3. Table 3 shows the results. The evaluations shown in Table 3 were: ：: the arc spot did not move for 10 hours or more, Δ: the arc spot moved within 5 minutes, ×: no arc discharge (only glow discharge in which the entire electrode was discharged). .

[0062]

[Table 3]

Table 3 shows that when the lamp current is 5 to 500 mA, the discharge can be maintained for a long time without moving the arc spot by selecting the average radius of curvature of the discharge surface from the range of 10 to 150 μm. When the arc spot moves, voltage fluctuations occur and ion sputtering tends to occur, and thermal shock is applied to the electron-emitting material, so that the life of the electrode is shortened.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a configuration example of a discharge lamp electrode of the present invention.

FIG. 2 is a flowchart for explaining a manufacturing process of a discharge lamp electrode according to the present invention.

FIG. 3 is a sectional view showing a configuration example of a discharge lamp having a discharge lamp electrode of the present invention.

FIG. 4 is a drawing substitute photograph showing a structure of a ceramic material, and is an EPMA image showing a Ba distribution on the surface of an electrode for a discharge lamp.

FIG. 5 is a drawing substitute photograph showing a structure of a ceramic material, and is an EPMA image showing a Ta distribution on a discharge lamp electrode surface.

FIG. 6 is a drawing substitute photograph showing the structure of a ceramic material, and is an EPMA image showing the Ba distribution on the surface of the discharge lamp electrode.

FIG. 7 is a drawing substitute photograph showing the structure of the ceramic material, and is an EPMA image showing the Ta distribution on the surface of the discharge lamp electrode.

FIG. 8 is a drawing substitute photograph showing the structure of the ceramic material, and is an EPMA image showing the Ba distribution on the surface of the discharge lamp electrode.

FIG. 9 is a drawing substitute photograph showing the structure of the ceramic material, and is an EPMA image showing the Ta distribution on the surface of the discharge lamp electrode.

FIG. 10 is a scanning electron microscope photograph of a cross section of an electrode for a discharge lamp, which is a drawing substitute photograph showing a particle structure.

FIG. 11 is a powder X-ray diffraction chart of an electron-emitting material.

FIG. 12 is a powder X-ray diffraction chart of a container.

FIG. 13 is a powder X-ray diffraction chart of the electron emission material.

FIG. 14 is a powder X-ray diffraction chart of the electron emission material.

FIG. 15 is a powder X-ray diffraction chart of the electron emission material.

FIG. 16 is an X-ray diffraction chart of a disc-shaped sintered body produced under the same conditions as the container.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Container 2 Electron emission material 3 Mercury dispenser material 4 Metal pipe 5 Lead wire 6 Lead wire enlargement part 7 Conductive pipe 9 Valve 10 Discharge space

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Makoto Takahashi 1-13-1 Nihonbashi, Chuo-ku, Tokyo TDK Corporation (72) Inventor Masatada Yodogawa 1-13-1 Nihonbashi, Chuo-ku, Tokyo TDK Co., Ltd. (72) Inventor Taku Harada 1-13-1, Nihonbashi, Chuo-ku, Tokyo TDC Corporation F-term (reference) 5C015 AA03 CC02 CC03 CC04 CC14 EE06

Claims (8)

[Claims] 1. An electronic device comprising: a cylindrical container having an open end; and an electron-emitting material accommodated in the container, wherein the container and the electron-emitting material are at least one of Ba, Sr, and Ca. A composite oxide containing one component, a second component composed of at least one of Zr and Ti, and a third component composed of at least one of Ta and Nb as a metal element component and / or a composite oxide containing nitrogen. An electrode for a discharge lamp, which is a main component, wherein the content of a first component on an exposed surface of the electron-emitting material as viewed from the opening side of the container is higher than the content of the first component on an end surface on the opening side of the container. 2. An electronic device comprising: a cylindrical container having an open end; and an electron-emitting material accommodated in the container, wherein the container and the electron-emitting material are made of at least one of Ba, Sr, and Ca. A composite oxide containing one component, a second component composed of at least one of Zr and Ti, and a third component composed of at least one of Ta and Nb as a metal element component and / or a composite oxide containing nitrogen. An electrode for a discharge lamp in which a main component is an electron-emitting material and is a porous body having a porosity of 45 to 80%. 3. The discharge lamp electrode according to claim 1, wherein the density of the container is 60% or more of the theoretical density. 4. The discharge surface has an average radius of curvature of 10 to 150 μm.
The discharge lamp electrode according to claim 1, wherein m is m. 5. A carbide containing at least one of Ta, Nb and Ti on an exposed surface of an electron-emitting material and an end surface on an opening side of the container as viewed from an opening side of the container and an outer surface and / or a bottom surface of the container. The electrode for a discharge lamp according to any one of claims 1 to 4, wherein a nitride is present. 6. The first component is M ^I , the second component is M ^II , and the third component is M ^I.
When representing the component M ^III, the container and the electron emission material, M ^I M ^II O ₃ type _{^{crystal, M I 5 M III 4 O}} 15 type _{^{crystal, M I 7 M III 6 O}} 22 type crystal, M ^I M ^III O ₂ N type crystals and _{^{M I 6 M II M III 4}} O 18 type according to claim 1 comprising at least one crystal selected from crystal
5. The electrode for a discharge lamp according to any of 5. 7. In the above crystal, part of M ^III is M ^II
7. The electrode for a discharge lamp according to claim 6, wherein M ^{I I} is substituted and a part of M ^{I I} is substituted by M ^III . 8. A discharge lamp having the discharge lamp electrode according to claim 1.