JP2001167731A - Discharge lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To significantly improve efficiency of a hot cathode discharge lamp and a cold cathode discharge lamp compared to the prior art, and also realize a discharge lamp life span at least equal to the prior art. SOLUTION: The discharge lamp has a rare gas-filled bulb and electrodes containing electron emission materials. The electron emission materials contain first metal element components consisting of at least one selected from Ba, Sr and Ca, and second metal element components consisting of at least one selected from Ta, Zr, Nb, Ti and Hf, and is based on at least one complex oxide selected from an MI4MII2O9 type crystal, an MIMII2O6 type crystal, an MIMIIO3 type crystal, an MI5MII4O15 type crystal, an MI7MII6O22 type crystal, and an MI6MIIMIII4O18 type crystal. When operating the hot cathode, a pressure of the filled gas is in the range of 60 to 270 Pa. When operating the cold cathode, a pressure of the filled gas is in the range of 1,300 to 20,000 Pa.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a hot cathode discharge lamp and a cold cathode 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 light sources and displays for general lighting has been actively promoted. For example, the replacement of incandescent light bulbs with bulb-type fluorescent lamps with higher energy efficiency and longer life, and the replacement of cathode ray tubes with liquid crystal displays with lower energy consumption are progressing rapidly. Along with that,
Fluorescent lamps are rapidly being used for light bulb-type fluorescent lamps and as backlight light sources for liquid crystal displays. Similarly, for cathode ray tubes such as cathode ray tubes, plasma displays, and fluorescent display tubes, there is a demand for electrodes having high energy efficiency and capable of saving energy.

Conventionally, BaO has been used as an electrode of a fluorescent lamp.
Oxide electrodes containing as a main component are generally used. Such an electrode is described in, for example, JP-A-59-75553. However, an oxide electrode containing BaO as a main component has good electron emission properties, but has high specific resistance. Therefore, when a large electron emission current is to be obtained, the temperature becomes high. As a result, the vapor pressure increases and the amount of evaporation increases, resulting in a problem that the life is shortened. Also, B
In the case of an oxide electrode containing aO as a main component, it is necessary to apply a current to a tungsten coil coated with a carbonate of Ba to convert the carbonate into an oxide, and to perform decarboxylation at that time. However, when this electrode is applied to a fluorescent lamp having a thin tube, decarboxylation tends to be insufficient, and as a result, carbon dioxide gas remains in the lamp bulb, causing unstable discharge or an extremely high luminance maintenance ratio. The problem is that it becomes worse.

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. The electrode has problems that it is susceptible to thermal shock, easily deteriorated by sputtering with Hg ions or rare gas ions, and has a small usable current density.

With respect to such a conventional fluorescent lamp electrode, the present inventors have proposed an electrode having a structure in which a ceramic semiconductor is housed in a cylindrical container having one end opened and one end closed. Various improvements have been made to the electrodes and to the discharge lamp using the electrodes (Japanese Patent Publication No.
No. 103627, Japanese Patent No. 2628312, Japanese Patent No. 2773174, Japanese Patent No. 2754647, Japanese Unexamined Patent Application Publication No.
-43546, JP-A-6-267404,
JP-A-9-129177, JP-A-10-1218
9, JP-A-6-302298, JP-A-7-302
No. 142031, JP-A-7-262983,
JP-A-10-3879). These electrodes have characteristics that they have good sputtering resistance and are hard to evaporate, so they are hardly deteriorated and have a long life. However, further improvements in sputtering resistance and resistance to evaporation are desired.

[0006]

In a hot cathode discharge lamp, generally, the lower the gas pressure, the higher the brightness. However, there is a problem that the life of the electrode is shortened when the filling gas pressure is reduced.

[0007] For example, WO 97/48121 states that "a phosphor is coated on the inner surface of a bulb, and Ba, Sr, C
a conductive oxide containing a first component consisting of at least one of a, a second component consisting of at least one of Zr and Ti, and a third component consisting of at least one of Ta and Nb, and having an aggregated porous structure. A ceramic cathode containing an electron-emitting material having a conductor layer or a semiconductor layer formed of at least one of carbides, nitrides and oxides of Ta or Nb on a surface thereof in a cylindrical container having a bottom; Is filled with a rare gas, and the charged pressure of the rare gas is 10
A ceramic cathode fluorescent discharge lamp having a pressure of Torr to 170 Torr "is described. This discharge lamp is of a type in which the ceramic cathode operates as a hot cathode. In this publication, the effect of the present invention is to realize high brightness and long life in a thin tube lamp.

In the embodiment of the publication, the outer diameter is 4 mm and the inner diameter is 3 m
m, using a discharge lamp with a bulb 100 mm long,
The lamp was turned on at a frequency of 30 kHz, a voltage of 80 V, and a lamp current of 30 mA, and the arc discharge life and luminance were measured. Here, the arc discharge life means that the arc discharge cannot be sustained,
This is the time required to shift to glow discharge. In this embodiment, an arc discharge life of about 4000 hours is obtained when the filling gas pressure is 10 Torr (1330 Pa) or more. However, when the filling gas pressure is 5 Torr (667 Pa), the arc discharge life is about 1000 hours. And the brightness has also been reduced.

On the other hand, a cold cathode discharge lamp can be easily made into a thin tube.
Because of their high efficiency, low power consumption, and long life, they are often used in, for example, liquid crystal display applications. In order to improve the luminous efficiency of the cold cathode discharge lamp, for example, Japanese Patent Application Laid-Open No. 9-356
No. 84 and JP-A-11-273617 propose to provide an emitter (electron emission material) on an electrode.

[0010] In the cold cathode discharge lamp, the luminous efficiency is improved when the gas pressure is reduced. Further, since the starting voltage can be reduced, the load on the transformer can be reduced. However, when the gas pressure in the cold cathode discharge lamp is reduced, the electrodes are easily sputtered, and the life is shortened.

SUMMARY OF THE INVENTION An object of the present invention is to provide a hot cathode discharge lamp and a cold cathode discharge lamp with significantly improved efficiency as compared with the conventional one and realizing a life equal to or longer than the conventional one.

[0012]

The above object is achieved by the following (1).
This is achieved by the present invention according to (5). (1) It has a valve filled with a rare gas and an electrode,
The electrode includes an electron emitting material, and the electron emitting material comprises
A metal component containing a first component comprising at least one of Ba, Sr and Ca and a second component comprising at least one of Ta, Zr, Nb, Ti and Hf;
^I ₄ M ^II ₂ O ₉ type crystals, M ^I M ^II ₂ O ₆ type crystals, M ^I M ^II O ₃ type _{^{crystal, M I 5 M II 4 O}} 15 type _{^{crystal, M I 7 M II 6 O}} 22 type crystals and _{^{M I 6 M II M II 4}} O 18 type as a main component at least one complex oxide selected from the crystal, the a pressure of rare gas 60~270Pa within the valve, the electrodes hot cathode A discharge lamp that operates. (2) having a valve filled with a rare gas and an electrode,
The electrode includes an electron emitting material, and the electron emitting material comprises
A metal component containing a first component comprising at least one of Ba, Sr and Ca and a second component comprising at least one of Ta, Zr, Nb, Ti and Hf;
^I ₄ M ^II ₂ O ₉ type crystals, M ^I M ^II ₂ O ₆ type crystals, M ^I M ^II O ₃ type _{^{crystal, M I 5 M II 4 O}} 15 type _{^{crystal, M I 7 M II 6 O}} 22 type crystals and a main component at least one complex oxide selected from the _{^{M I 6 M II M II 4}} O 18 type crystals, the pressure of the rare gas within said valve a 1300～20000Pa, the electrodes cold cathode A discharge lamp that operates. (3) the electron emitting material, the discharge lamp of the above (1) or (2) as a main component M ^I ₅ M ^II ₄ O ₁₅ type crystal. (4) In the electron-emitting material, when the molar ratio of the first component is X and the molar ratio of the second component is Y with respect to the total of the first component and the second component, 0.8 ≦ X / The discharge lamp according to any one of (1) to (3), wherein Y ≦ 1.5. (5) The discharge lamp according to any one of (1) to (4), wherein a part of the second component in the electron-emitting material is contained as a carbide and / or a nitride.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The above composite oxide contained in the electron emitting material used in the present invention has a low vapor pressure. Therefore, B
Electrode deterioration due to evaporation is less than that of a conventional electrode material mainly containing aO. In addition, the above-mentioned WO97
Ba-Zr-T described in US Pat.
Electrode deterioration is reduced as compared with an electrode made of an a-based composite oxide. Therefore, when applied to an electrode that performs hot cathode operation, the electrode life is significantly prolonged.

According to the present invention, when the electron-emitting material containing the composite oxide is applied to a hot cathode discharge lamp, the gas pressure is 60 to 270 Pa, which is significantly lower than that of a conventional hot cathode discharge lamp. The efficiency is significantly improved. In addition, at this time, the life of the discharge lamp is equal to or longer than that of the conventional hot cathode discharge lamp.

The above-mentioned composite oxide is hardly consumed even by ion sputtering. Therefore, even in a cold cathode operation in which ion sputtering is intensified due to a large cathode drop voltage, wear is small and a long life is realized.

In the present invention, when the electron-emitting material containing the composite oxide is applied to a cold cathode discharge lamp, the charged gas pressure is 1300 compared to a conventional cold cathode discharge lamp commercially available.
Since the pressure is relatively low, that is, up to 20,000 Pa, the luminous efficiency is remarkably improved, and the starting voltage can be lowered. In addition, at this time, the life of the discharge lamp is equal to or longer than that of the conventional cold cathode discharge lamp.

The reason why the electron-emitting material used in the present invention achieves the above-mentioned high characteristics is that it contains the above-mentioned composite oxide.

Hereinafter, the electron emitting material used in the present invention will be described in detail.

Electron emitting materials The electron emitting materials used in the present invention are Ba, Sr and Ca.
A first component comprising at least one of the following: Ta, Zr, N
b, a second component comprising at least one of Ti and Hf is included as a metal element component. The first component is a low work function electron emission component. The second component is a component necessary for lowering the resistance and increasing the melting point of the electron-emitting material. The proportion of Ta in the second component is 98 atomic% or less, preferably 95 atomic% or less. Ta in the second component
Is too high, the evaporation temperature of the first component (especially Ba) becomes low, and the life of the discharge lamp may be slightly shortened.

The electron emission material used in the present invention contains a composite oxide as a main component. When the first component is represented by M ^I and the second component is represented by M ^II , the composite oxide is represented by M ^I ₄
M ^II ₂ O ₉ type crystals, M ^I M ^II ₂ O ₆ type crystals, M ^I M ^II O ₃ type _{^{crystal, M I 5 M II 4 O}} 15 type _{^{crystal, M I 7 M II 6 O}} 22 type crystals and M ^At least one selected from ^I ₆ M ^II M ^II ₄ O ₁₈ type crystals
Is a seed. The electron-emitting material used in the present invention includes compounds other than composite oxides (excluding carbides and nitrides described later) because of its high performance as an electron-emitting material and high stability as a compound. Preferably not. Among the above composite oxides, at least M ^I ₅ M ^II ₄
It preferably contains O ₁₅ type crystals. When containing M ^I ₅ M ^II ₄ O ₁₅ type crystal, lamp life is longest. M ^I ₅ M
^{In the II} ₄ O ₁₅ type crystal, the molar ratio of oxygen is not limited to 15. In the actual product, the range of the molar ratio of oxygen is expressed as 15 ± δ due to the presence of oxygen defects and the like.
Here, δ is preferably 0.5, more preferably 0.3.
It is. If the molar ratio of oxygen is in such a range,
The effect of suppressing the consumption of the electron-emitting material due to evaporation and sputtering is enhanced.

Note that WO 97/24749 discloses that
It is described that Ba ₅ Ta ₄ O ₁₅ can be selected as an electron-emitting substance for coating an electrode of a low-pressure discharge lamp. However, in the publication Example of Ba ₅ Ta ₄ O ₁₅ is not described, the characteristics has not been confirmed.

The electron-emitting material is, in addition to the above composite oxide,
It may contain carbides and / or nitrides, especially M ^II carbides such as TaC. This carbide or nitride is contained as a result of part of the second component becoming carbide or nitride in the process of producing the electron-emitting material, as described later.
Since these carbides and nitrides are substances having a high melting point and high conductivity, even if they are contained, the electron emission characteristics and the sputtering resistance are not impaired at all. The second
Of the components, for example, Ta is likely to be carbide, and Zr is likely to be nitride.

The presence of each crystal in the electron-emitting material can be confirmed by X-ray diffraction. FIG. 6 shows a typical X-ray diffraction pattern of the electron-emitting material used in the present invention. The pattern shown in FIG. 6 is for an electron emitting material consisting essentially of a single phase of ^MI ₅ M ^II ₄ O ₁₅ . Electron-emitting material used in the present invention is preferably composed mainly of M ^I ₅ M ^II ₄ O ₁₅ type crystal as mentioned above, it is more preferably composed of substantially only the crystal. However, as described above, there is no problem even if carbides and / or nitrides are contained. Note that the M ^I ₅ M ^II ₄ O ₁₅ type crystal as a main component, when comparing the maximum peak intensity of each crystal in X-ray diffraction pattern, of _{^{M I 5 M II 4 O 1}} 5 other than the crystalline maximum peak intensity less than 50% of the maximum peak intensity of M ^I ₅ M ^II ₄ O ₁₅ type crystal, preferably means that 30% or less. The determination as to whether or not the other composite oxide is the main component is performed in the same manner. However, for example, B
When two or more kinds of oxides whose maximum peak positions are almost the same, such as aZrO ₃ and Ba ₅ Ta ₄ O ₁₅ , are generated at the same time, the intensity of the second largest peak is used, and it compares the maximum peak of M ^I ₅ M ^II ₄ O ₁₅ type crystal.

In the electron-emitting material, when the molar ratio of the first component is X and the molar ratio of the second component is Y with respect to the total of the first component and the second component, preferably 0.8 ≦ X / Y ≦ 1.5, more preferably 0.9 ≦ X / Y ≦ 1.2. If X / Y is too small, the first component will be depleted early due to discharge, and the sputtering resistance will be insufficient. On the other hand, if X / Y is too large, the electron-emitting material is likely to be evaporated and scattered by sputtering during discharge. Therefore, in any case, for example, when the present invention is applied to a discharge lamp, the brightness is easily reduced due to blackening of the tube wall.

The electron emission material may contain a metal element component other than the first component and the second component. As such a metal element component, an element M (M is Mg, Sc,
Y, lanthanoid, V, Cr, Mo, W, Fe, Ni and at least one of Al). Element M is
It is added as needed to improve sinterability. The content of the element M in the electron-emitting material is preferably 10% by mass or less, more preferably 5% by mass or less in terms of oxide. If the content of the element M is too large, the melting point of the electron-emitting material becomes low, so that the vapor pressure at the time of high temperature use becomes high and the life is shortened. On the other hand, the content of the element M is preferably 0.5% by mass or more in order to sufficiently exert the effect of the addition of the element M. The content in terms of oxide means an oxide having a stoichiometric composition, that is, MgO,
Sc ₂ O ₃ , Y ₂ O ₃ , lanthanoid oxide (La ₂ O
₃ etc.), V ₂ O ₅ , Cr ₂ O ₃ , MoO ₃ , WO ₃ , Fe
It is the content calculated in terms of ₂ O ₃ , NiO and Al ₂ O ₃ .

The element M contains M ^I in the above-mentioned composite oxide.
Or a part of M ^II or a state mixed with the composite oxide as an oxide, a nitride, a carbide, or the like without being substituted. Note that the fact that part of M ^I or part of M ^{II in} the composite oxide crystal is replaced by another metal element can be confirmed by a shift in peaks and a change in peak intensity ratio in X-ray diffraction. it can.

The electron-emitting material used in the present invention exhibits excellent performance as an electron-emitting material at an operating temperature (normally, about 900 to 1400 ° C. for a hot cathode and about 700 to 1000 ° C. for a cold cathode), and has a large discharge current. Even when the temperature becomes high by flowing, the consumption is small due to the low vapor pressure.

Manufacturing Method of Electron Emitting Material In order to obtain the electron emitting material used in the present invention as a powder or a sintered body, for example, a method shown in FIG. 1 can be used. Hereinafter, each step will be described.

[0029]Weighing process In the weighing step, the starting materials are weighed according to the final composition.
Compounds used as starting materials are oxides and / or
Compounds that become oxides upon firing, such as carbonates and oxalates
Or the like may be used, but usually the compound containing the first component
Is BaCO_Three, SrCO_ThreeAnd CaCO_ThreeUsing
And the compound containing the second component is Ta._TwoO_Five,
ZrO_Two, Nb_TwoO_Five, TiO_TwoAnd HfO_TwoUsing
Is preferred. Further, as a starting material of the element M,
MgCO_Three, Sc_TwoO_Three, Y_TwoO_Three, Lanthanoid oxide
(La_TwoO_ThreeEtc.), V_TwoO_Five, Cr_TwoO_Three, MoO_Three, WO_Three,
Fe _TwoO_Three, NiO and Al_TwoO_ThreeIt is preferable to use
No.

Mixing Step In the mixing step, the weighed starting materials are mixed to obtain a raw material powder. For mixing, a method such as a ball mill method, a friction mill method, and a coprecipitation method can be used. After mixing, drying is performed by a dehydration heating drying method or a freeze drying method.

[0031] In the firing step baking step, the raw material powder may be calcined in an oxidizing atmosphere as in air or in a reducing atmosphere, but since the electron emission property becomes excellent, preferably calcined in a reducing atmosphere . The firing temperature is preferably 800 to 1700 ° C, more preferably 800 to 1500 ° C, and still more preferably 9 to 1700 ° C.
00 to 1300 ° C. If the firing temperature is too low, M ^I ₅ M
Complex oxides such as ^II ₄ O ₁₅ are not easily generated, and the performance as an electron-emitting material tends to be insufficient. On the other hand, if the firing temperature is too high, sintering proceeds and it becomes difficult to pulverize, and the composite oxide may be melted or decomposed. The firing time (temperature holding time) may be generally about 0.5 to 5 hours. This baking may be performed in a powder state, or may be performed in a state in which the powder is molded for easy handling.

As a gas constituting the reducing atmosphere, a neutral gas such as nitrogen, an inert gas such as Ar, a reducing gas such as CO or H _2, or a gas containing carbon (for example, benzene or monoxide) Carbon etc.). When calcined in these gases, carbides and / or nitrides of the second component may be simultaneously generated in addition to the composite oxide.

[0033] In the pulverization step grinding process, grinding the electron-emitting material obtained in the firing step. For this pulverization, a ball mill or airflow pulverization may be used. By providing a pulverizing step, the particle size of the electron-emitting material can be reduced, and the particle size distribution can be narrowed.
The electron emission property can be improved and its variation can be reduced.
Therefore, it is preferable to provide a pulverizing step. When a sintered body is finally obtained, the process proceeds to the next forming step.

After the pulverization, a granulation step is provided if necessary.
In the granulation step, the pulverized powder is granulated using an aqueous solution containing an organic binder such as polyvinyl alcohol (PVA), polyethylene glycol (PEG), and polyethylene oxide (PEO). Granulation means is not particularly limited, for example, spray drying method, extrusion granulation method, tumbling granulation method, mortar,
A method using a pestle or the like can be used.

Molding Step In the molding step, a compact having the desired electrode shape is obtained by compression molding.

Sintering Step In the sintering step, the compact is fired to obtain a sintered body (electrode). The firing temperature is preferably from 800 to 2000 ° C, more preferably from 1100 to 1700 ° C. If the firing temperature is too low, the density of the sintered body tends to be insufficient, and if the firing temperature is too high, a compositional deviation occurs or it tends to react with the setter. The firing time may usually be about 0.5 to 5 hours.

It should be noted that a molding step may be provided after the mixing step, and the firing step may also serve as the sintering step.

The firing atmosphere is not particularly limited, and may be an oxidizing atmosphere such as in air or the above-described reducing atmosphere.

Method for Manufacturing Electron Emitting Material Film In obtaining the electron emitting material as a film, for example, a method shown in FIG. Less than,
Each step will be described.

[0040] performed in the same manner as the weighing process shown in weighing Scheme 1.

Mixing Step The mixing step is performed in the same manner as in the mixing step shown in FIG.

Slurry Preparation Step In the slurry preparation step, a mixture of starting materials is slurried. When performing wet mixing in the mixing step,
It is preferable that the mixing step also serves as a slurry preparation step. The dispersion medium used for slurrying may be aqueous or organic as described in the mixing step.

In the slurry preparation step, a binder is added as required. The type of the binder is not particularly limited, and for the organic dispersion medium, for example, ethyl cellulose, may be appropriately selected from various ordinary binders such as polyvinyl butyral, and for the aqueous dispersion medium, for example, polyvinyl alcohol, cellulose, A water-soluble acrylic resin or the like may be used.

The solid concentration in the slurry or the viscosity of the slurry may be appropriately determined according to the method of forming the coating film. Generally, the viscosity of the slurry is preferably about 0.01 to 10 ⁵ mPa · s. .

The coating film-forming step In this step, a coating film is formed on the substrate surface using a prepared slurry. The base material is not particularly limited, and may be any of various metals and ceramics.

The method for forming the coating film is not particularly limited, and may be appropriately selected from various methods such as a printing method, a doctor blade method, and a spraying method according to the required film thickness and the like.

Firing Step In the firing step, the coating film is fired in the same manner as the firing step in the method shown in FIG.

In the method shown in FIG. 2, the composite oxide is formed in the coating film. However, in addition to the method shown in FIG. 2, a method in which the composite oxide is generated before forming the coating film is also used. it can. That is, a coating film is formed in the same manner as in the above-mentioned coating film forming step using the electron-emitting material powder obtained by using the method shown in FIG. 1, and this coating film is subjected to a heat treatment for drying and removing the binder. , An electron emission material film may be obtained.

Electrode The above-mentioned electron-emitting material is applied to an electrode operating as a hot cathode or an electrode operating as a cold cathode.

FIG. 3 shows an example of electrodes for hot cathode operation. This electrode has a structure in which a granule 2 made of a ceramic semiconductor is accommodated in a cylindrical container 1 having one end opened and one end closed.
The above-mentioned electron-emitting material is used as a ceramic semiconductor for this electrode. In addition, it may be used for the cylindrical container 1. This electrode functions as a cold cathode at the beginning of energization,
This type shifts to hot cathode operation by self-heating.

As another hot cathode, for example, the above-mentioned electron-emitting material is formed into a rod-shaped sintered body, and this sintered body is inserted into a hollow portion of a tungsten coil and fixed to form a hot cathode. May be. In addition, a hot cathode can be formed by forming an electron emission material film on the surface of a base material that is a linear body (a coil-shaped or double-coiled filament or the like) or a plate-shaped body. As the base material, for example, W,
Various metals such as Mo, Ta, Ni, Zr, Ti, or alloys containing at least one of these, or Zr
Ceramics such as O ₂ , Al ₂ O ₃ , MgO, AlN, and Si ₃ N ₄ or ceramics containing at least one of these (SIALON, etc.) can be used. In addition, a coating film containing a composite oxide-containing powder or a raw material powder that produces a composite oxide by firing and a coating film containing a conductive material are laminated by a printing method or a sheet method, and this is fired. To form a stacked electrode.

Conventionally, a metal tubular body made of Ni or the like is generally used for the cold cathode. When an emitter is used, the tubular body is used as an electrode base material and the peripheral surface thereof is used. For example, an emitter coating made of BaO is provided. When the present invention is applied to a cold cathode discharge lamp, a coating containing the above-mentioned electron-emitting material may be provided on the surface of the electrode substrate instead of the conventional emitter coating. In addition, as a constituent material of the electrode substrate, in addition to Ni, for example, W, Ti, Zr, Mo, T
A high melting point metal such as a or an alloy containing at least one of these metals can be preferably used.

When the electron-emitting material used in the present invention is used as a film, the thickness of the film may usually be about 5 to 1000 μm. The average particle size of the electron emitting material particles in the electron emitting material film is preferably 0.05 to 20 μm, and more preferably 0.1 to 10 μm. In order to further reduce the average particle size in the film, fine particles that are difficult to handle must be used. In addition, such fine particles are likely to aggregate into secondary particles, so that the particle size distribution is widened and it is difficult to form a uniform coating film. On the other hand, if the average particle size in the film is too large, the particles of the electron-emitting material tend to fall off, and the workability during coating is also poor, and the electron-emitting properties are also poor.

[0054] In the discharge lamp 4 shows a configuration example of a discharge lamp of hot cathode operation having an electrode shown in FIG. 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 60 to 270 Pa, preferably 60 to 200 Pa. By setting the pressure of the rare gas in this range,
The luminous efficiency can be significantly improved, and a sufficiently long lifetime can be realized.

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. Further, 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 turned 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 section 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.

FIG. 5 shows an example of the configuration of a discharge lamp operating in the cold cathode mode. It should be noted that only the vicinity of the pipe end is shown in FIG.

This discharge lamp has a bulb 9 which is coated with a phosphor 9A on the inner surface and hermetically sealed. A rare gas is sealed in the valve 9. The pressure of the rare gas in the valve 9 is 1300 to 20000 Pa, preferably 26 to 20,000 Pa.
It is 00-13000 Pa. By setting the pressure of the rare gas in this range, the luminous efficiency can be significantly improved, and a sufficiently long lifetime can be realized.

The lead wire 5 is inserted through the end of the valve 9. At the end of the lead wire 5 existing in the valve 9, an internal introduction line 6A is provided through a stem 9B closing the valve end. A conductive pipe 7 serving as an electrode substrate is connected to the internal introduction line 6A. On the inner peripheral surface of the conductive pipe 7, an electron emission material film 2A is formed. This discharge lamp has a structure in which mercury is supplied into a bulb during a sealing process.

The present invention is applicable not only to the discharge lamp having the structure shown in FIGS. 4 and 5. For example, the invention can be applied to various types of discharge lamps already proposed by the present inventors in the above publications.

[0061]

EXAMPLES Example 1 (Hot Cathode Discharge Lamp) An electron-emitting material was manufactured according to the following procedure.

First, BaCO ₃ , Ta ₂ O ₅ and ZrO ₂ were prepared as starting materials for the first and second components.
The mixture was wet-mixed for 20 hours using a ball mill. The molar ratio of the starting materials is represented by the molar ratio X of the first component and the molar ratio Y of the second component.
Was selected from the range where 0.9 ≦ X / Y ≦ 1.2.

Next, after drying the mixture, 1100
In air at a temperature selected from the range of 1400 ° C.
After firing for an hour, an electron emission material was obtained. Each electron-emitting material was wet-pulverized by a ball mill for 20 hours, and then dried to obtain an electron-emitting material powder having an average particle diameter of 0.8 μm.

When these powders were analyzed by X-ray diffraction, substantially no peak other than the composite oxide was observed in all the powders. Table 1 shows the crystal forms determined as the main components of each powder by X-ray diffraction. Also, FIG. 6 shows a _{Ba 5 (Ta 0.9 Zr 0. 1} ) 4 O 15 X -ray diffraction pattern of the powder of crystal.

In these electron-emitting material powders, the composition ratio of the metal element component was almost the same as that of the starting material. The composition ratio of the metal element components was measured by X-ray fluorescence analysis.

Next, a 1% aqueous solution of polyethylene oxide was added to each electron emitting material powder to form a slurry. This slurry was applied to a tungsten double coil filament mounted on a stem, and the slurry was applied in air for 10 minutes.
After drying at 0 ° C. for 30 minutes, an electrode was obtained. The application amount of the electron emission material was 1.0 mg. This coating amount is 1/5 of the usual amount, but this is to evaluate the lamp life in a short time.

Next, this electrode was used for a total length of 100 m of the bulb.
m, outer diameter 8 mm, filling gas Ar, filling material Hg (filling amount 5 m
g), incorporated in a discharge lamp having a driving power supply frequency of 30 kHz and a lamp current of 120 mA to obtain a measurement sample. Note that a plurality of samples were prepared for each powder while changing the filling gas pressure within the range shown in Table 1. Since the vapor pressure of mercury is several Pascals, in Table 1, the gas pressure including the mercury vapor pressure is used as the filling gas pressure.

For comparison, a BaO-based electron-emitting material {(Ba, Sr, Ca) O +
A discharge lamp sample using ZrO ₂作 製 was also prepared.

A continuous lighting test was performed on these samples to evaluate luminous efficiency and lamp life. Table 1 shows the results. The luminous efficiency shown in Table 1 is a relative value when the luminous efficiency of a sample using a BaO-based electron-emitting material and the filling gas pressure is 270 Pa is defined as 100%. In addition, the lamp life shown in Table 1 is the time until the arc discharge becomes unstable and the lamp voltage fluctuates by 20% or more.

[0070]

[Table 1]

From Table 1, it can be seen that, when the alkaline earth metal oxide as the conventional emitter is used, the luminous efficiency is increased by setting the filling gas pressure to 270 Pa or less, but the lamp life is significantly shortened. On the other hand, the composite oxide limited in the present invention, in particular, Ba ₅ (Ta _0.9 Zr _0.1 ) ₄
In the sample of the present invention using the electron-emitting material containing the O ₁₅ crystal, the lamp life is sufficiently long even when the filling gas pressure is 270 Pa or less. The sample of the present invention has a sealed gas pressure of 60.
Up to Pa, the lamp life is equal to or longer than that of the conventional emitter, and the luminous efficiency at the filling gas pressure of 60 Pa reaches about 1.7 times that of the comparative sample having the same lamp life.

Example 2 (Cold Cathode Discharge Lamp) Using a part of the electron emission material produced in Example 1, a cold cathode discharge lamp sample having the structure shown in FIG. 5 was produced. The electrodes are
Using a Ni cylinder as a base material, the inner peripheral surface of this base material is
It was manufactured by forming an electron emission material film in the same manner as in Example 1. The application amount of the electron emission material was 2 mg. This electrode was assembled in a discharge lamp having a total length of the bulb of 100 mm, an outer diameter of 3 mm, a filling gas Ar (filling gas pressure of 5300 Pa), a filling substance Hg (filling amount of 2 mg), and a driving power supply frequency of 30 kHz to obtain a measurement sample. Since the vapor pressure of mercury is several Pascals, the gas pressure including the vapor pressure of mercury is used here.

For comparison, a sample was also prepared in which an electrode substrate itself was used as an electrode without forming a coating film of an electron-emitting material.

A continuous lighting test was performed on these samples to evaluate luminous efficiency and lamp life. The results shown in FIGS. 7 to 9 were obtained. 7 to 9,
The sample of the present invention using the composite oxide as the electron-emitting material is indicated by (A), and the sample using the BaO-based electron-emitting material as the electron-emitting material is indicated by (B). (C)
It is indicated by.

FIG. 7 shows the relationship between the lamp current and the lamp voltage for each of (A) to (C). If the lamp conditions (bulb size and sealed gas pressure) are the same, the lower the lamp voltage, the higher the luminous efficiency. Since lamp current and luminance are almost proportional, the lamp current (luminance)
Are the same and the lamp voltage is low, the same brightness can be obtained with less power, that is, the efficiency is high. From FIG. 7, it can be seen that the lamp voltage is high and the luminous efficiency is low in the case of (C) using only the Ni cylinder, but that the luminous efficiency is improved when the electron emission material used in the present invention is coated because the lamp voltage is lowered. .

FIG. 8 shows the relationship between the lighting time and the lamp voltage for each of (A) to (C). This result is obtained when the lamp current is 5 mA. In FIG. 8, in (C) using a Ni cylinder, the lamp voltage is 1
Although stable after 0000 hours, the lamp voltage is high and the luminous efficiency is low. In the case of (B) coated with a BaO-based electron-emitting material, the lamp voltage is low at first, but after 3000 hours or more, BaO and the like and the enclosed mercury are amalgamated to deplete mercury. As a result, the lamp voltage increased, and the lamp eventually stopped lighting. On the other hand, the sample (A) of the present invention is 10,000
It can be seen that the lamp voltage is maintained low even after the elapse of time, the luminous efficiency is high, and the life is long.

FIG. 9 shows the relationship between the lighting time and the luminance maintenance ratio for each of (A) to (C). This result is obtained when the lamp current is 5 mA. In FIG. 9, a BaO-based electron emitting material was coated (B).
However, after 2000 hours, the luminance maintenance ratio decreases to 85%. This is presumably because the amalgamation of BaO or the like with mercury causes discoloration of the bulb wall of the bulb to proceed.
In contrast, the sample of the present invention (A) is 10,000
Even after a lapse of time, the luminance maintenance rate of about 90% was exhibited.
The luminance maintenance ratio is better than (C) using a cylinder made.
As can be seen from FIG. 7, (A) has a low lamp voltage,
It is considered that the electrode was less consumed by ion sputtering, and as a result, discoloration of the tube wall, which was caused by amalgamation of the electron-emitting material and mercury, was suppressed.

In FIGS. 8 and 9, the lamp current 5
The results at mA were shown, but the effect of the present invention was observed in the entire range of the lamp current (1 to 10 mA) shown in FIG. 7 as in FIGS. 8 and 9.

FIG. 7 to FIG.
The results when the pressure was set to 00 Pa were shown, but the charged gas pressure was 130 Pa.
Also in the range of 0 to 20000 Pa, it has been confirmed that the present invention improves the efficiency of the lamp and prolongs the life, similarly to the results shown in FIGS.

In each of the above embodiments, Ba was used as the first component, and Ta and Zr were used as the second component.
In the case where at least one of Sr and Ca is used in place of at least a part of Nb, Ti and Hf in place of at least one of Ta and Zr, Similar effects were obtained.

[0081]

As described above, the electron-emitting material used in the present invention contains the above-mentioned composite oxide, so that it is less likely to evaporate at high temperatures.
In addition, there is little consumption when ion sputtering is performed. Therefore, the discharge lamp of the present invention using this electron-emitting material exhibits a lamp life equal to or longer than that of the related art even when the luminous efficiency is significantly improved as compared with the related art by setting the filling gas pressure lower than before. Therefore, according to the present invention, an extremely efficient discharge lamp can be put to practical use.

[Brief description of the drawings]

FIG. 1 is a flowchart showing steps in producing an electron emitting material used in the present invention as a powder or a sintered body.

FIG. 2 is a flowchart showing steps in producing an electron-emitting material used in the present invention as a film.

FIG. 3 is a cross-sectional view illustrating a configuration example of an electrode.

FIG. 4 is a sectional view showing a configuration example of a hot cathode discharge lamp.

FIG. 5 is a sectional view showing a configuration example of a cold cathode discharge lamp.

FIG. 6 is an X-ray diffraction pattern of the electron-emitting material used in the present invention.

FIG. 7 is a graph showing a relationship between a lamp current and a lamp voltage in a cold cathode discharge lamp.

FIG. 8 is a graph showing a relationship between a lighting time and a lamp voltage in a cold cathode discharge lamp.

FIG. 9 is a graph showing a relationship between a lighting time and a luminance maintenance ratio in a cold cathode discharge lamp.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Container 2 Electron emission material 2A Electron emission material film 3 Mercury dispenser material 4 Metal pipe 5 Lead wire 6 Lead wire expansion part 6A Internal introduction line 7 Conductive pipe 9 Valve 9A Phosphor 9B Stem 10 Discharge space

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Akira Takeishi 1-13-1 Nihonbashi, Chuo-ku, Tokyo Inside TDK Corporation (72) Inventor Makoto Takahashi 1-13-1 Nihonbashi, Chuo-ku, Tokyo TDK Incorporated (72) Inventor Masatada Yodogawa 1-13-1 Nihonbashi, Chuo-ku, Tokyo FDC term (reference) 5C015 BB02 CC02 CC03 CC04

Claims (5)

[Claims] 1. A valve in which a rare gas is sealed, and an electrode, the electrode including an electron-emitting material, wherein the electron-emitting material comprises a first component comprising at least one of Ba, Sr, and Ca. , Ta, Zr, Nb, and a second component consisting of at least one Ti and Hf as the metal element ^{_{component, M I 4 M II 2 O}} 9 type crystals, M ^I M ^II ₂ O ₆ type crystals, M ^I M ^II O ₃ type ^{_{crystal, M I 5 M II 4 O}} 15 type crystal, the at least one composite selected from M ^I ₇ M ^II ₆ O ₂₂ type crystals and ^{_{M I 6 M II M II 4}} O 18 type crystals A discharge lamp mainly composed of an oxide, wherein the pressure of the rare gas in the bulb is 60 to 270 Pa, and the electrode performs a hot cathode operation. 2. A valve having a rare gas sealed therein and an electrode, the electrode including an electron-emitting material, wherein the electron-emitting material comprises a first component comprising at least one of Ba, Sr and Ca. , Ta, Zr, Nb, and a second component consisting of at least one Ti and Hf as the metal element ^{_{component, M I 4 M II 2 O}} 9 type crystals, M ^I M ^II ₂ O ₆ type crystals, M ^I M ^II O ₃ type ^{_{crystal, M I 5 M II 4 O}} 15 type crystal, the at least one composite selected from M ^I ₇ M ^II ₆ O ₂₂ type crystals and ^{_{M I 6 M II M II 4}} O 18 type crystals The pressure of the rare gas in the valve is 1300-200
00 Pa, wherein the electrode performs a cold cathode operation. Wherein the electron emission material, the discharge lamp according to claim 1 or 2 as a main component M ^I ₅ M ^II ₄ O ₁₅ type crystal. 4. The method according to claim 1, wherein the molar ratio of the first component to the total of the first component and the second component is X,
The discharge lamp according to claim 1, wherein when the molar ratio of the second component is Y, 0.8 ≦ X / Y ≦ 1.5. 5. The discharge lamp according to claim 1, wherein a part of the second component is contained as a carbide and / or a nitride in the electron emission material.