KR20040072887A - Cathode for electron tube - Google Patents

Abstract

PURPOSE: A cathode for an electron tube is provided to improve the property of electron radiation by preventing oxidation of a gas metal. CONSTITUTION: A cathode for electronic tube comprises a gas metal(16) constituted by nickel as a main component, an adhesion, an adhesion solvent for smelting the adhesion, and an electron radiating material layer(11). An alkali-earth metal oxide suspension is deposited on the electron radiating material layer. A metal compound is constituted by the same chemical group as the chemical group of the adhesion solvent in order to be smelted to the adhesion solvent.

Description

Electrode Tube Cathode {CATHODE FOR ELECTRON TUBE}

The present invention relates to a cathode for an electron tube, and more particularly to an anode for an electron tube that can improve electron emission characteristics of the cathode.

In general, an electron tube is an electronic device using electric conduction by electrons moving in a sealed container, and is an active element of an electronic circuit capable of rectifying, amplifying, oscillating, modulating, and demodulating (detecting). The electron tube has a cathode that emits electrons in the hermetic container, a control electrode that controls the flow of electrons emitted therein, and an electrode that collects electrons, that is, an anode, each having a positive or negative amount appropriate for the electrodes. A voltage is applied to control the magnitude and direction of the electron stream.

The cathode ray tube of the electron tube is used to tighten the electron flow to have a narrow cross-sectional area to make a beam state. The electron tube is used together with various other electronic components to form various electronic devices such as televisions, stereos, and other electronic devices, radio receivers, and communication devices.

1 is a cross-sectional view showing a cathode for an electron tube according to the prior art.

The cathode for an electron tube according to the prior art has a cylindrical sleeve (6) provided with a heating heater (2) inserted therein, and a main component of nickel (Ni) on the upper end of the sleeve (6). ), A base metal 5 containing a trace amount of a reducing agent such as magnesium (Mg), and barium (Ba) on the upper portion of the base metal (5), as well as strontium (Sr), calcium (Ca) and the like. It consists of an electron-emitting material layer (1) composed of alkaline earth metal oxides.

The electron-emitting material layer (1) is formed by applying an alkaline earth metal oxide suspension on the base metal (5), wherein the alkaline earth metal oxide suspension is an alkaline earth metal oxide containing barium and the alkaline earth metal oxide An adhesive for adhering on top of the base metal and an adhesive solvent for dissolving the adhesive are mixed.

The adhesive is mainly composed of nitrocellulose, and the adhesive solvent generally includes chemical groups of acetate, carbonate, and oxalate.

Such an electron tube cathode is manufactured by the following process.

First, an alkali earth metal carbonate suspension containing barium is applied onto the base metal and heated by the heater 2 in the vacuum evacuation process of the electron tube. Through this process, the alkaline earth metal carbonate is an alkaline earth metal oxide. Changes to.

Here, the alkaline earth metal oxide is an alkaline earth metal carbonate state before passing through a process such as a shopping mall, but for the sake of unification with the related art, the alkaline earth metal oxide will be described collectively.

In addition, in the high temperature activation process of 900 ° C. to 1000 ° C., an activation element such as silicon or magnesium included in the base metal 5 is diffused to an interface between the electron-emitting material layer 1 and the base metal 5 by diffusion. It moves and chemically reacts with the alkaline earth metal oxide contained in the electron-emitting material layer 1, and part of the alkaline earth metal oxide is reduced by the activating metal in the base metal to have semiconductor properties.

As a result, the electron-emitting material layer 1 becomes an oxygen deficient semiconductor lacking a part of the alkaline earth metal oxide, and has an electron emission characteristic of 0.5 to 0.8 A / cm 2 under normal temperature conditions.

However, in the conventional electron tube cathode configured as described above, the alkali earth metal oxide in the electron-emitting material layer 1 in the grain boundary of or adjacent to the base metal 5 and the activated metal in the base metal 5 During the reaction process, the reactant is formed of a high-resistance layer oxide, so that the cathode current is limited by the reactant, and the crystallization of the electron-emitting material is promoted by the generation of joule heat of the reactant.

In addition, the reactants limit the production of barium by preventing the activating element in the gaseous metal from diffusing into the electron-emitting material layer. For this reason, when a high current is used in the electron tube, the cathode current deteriorates rapidly and the life is shortened.

BaCO₃ (electron-emitting material) = BaO (electron-emitting material oxide) + CO₂ (1)

BaO (electro-radioactive oxide) + Mg (gas metal) = Ba + MgO (reactant) (2)

2BaO (electro-radioactive oxide) + Si (gas metal) = 2Ba + SiO₂ (reactant) (3)

4BaO (electro-radioactive oxide) + Si (gas metal) = 2Ba + Ba₂SiO₄ (reactant) (4)

As a method for improving the adverse effects of the reactants as described above, the cathode for an electron tube disclosed in Korean Patent Laid-Open Publication No. 10-1987-0001629 (Application No. 10-1986-0005652) is a base metal containing nickel (Ni) as a main component. And an electron-emitting material layer containing 0.1 to 20% by weight of rare earth metal oxides or 0.05 to 15% by weight of rare earth metals based on alkaline earth metal oxides containing at least barium on the base metal. In another embodiment, the cathode includes a coating layer composed of a base metal containing nickel (Ni) and a rare earth metal oxide having a thickness of 10 μm or less or a rare earth metal having a thickness of 6 μm or less and a coating layer thereof. Is provided with an electron-emitting material layer composed of an alkaline earth metal oxide containing at least barium.

In addition, as another embodiment of the Korean Patent Laid-Open Publication No. 10-1987-0001629, the cathode is a gas metal and barium containing nickel (Ni) as a main element and containing a rare-tube metal of 0.01 to 0.5% by weight (%) It is provided with an electron-emitting material layer composed of an alkaline earth metal oxide.

Here, the rare earth metal oxide is subjected to high temperature heat treatment in a reducing atmosphere of 800 ° C. or more before mixing with the alkaline earth metal oxide.

In addition, Japanese Patent Laid-Open Nos. 5-266783 (Application No. 2-408884) and Japanese Patent Laid-Open No. 7-211222 (Application No. 7-29409) related to the Korean Laid-Open Patent Publication No. 10-1987-0001629. The cathode for an electron tube interposed therein has been improved in order to have stable electrospinning characteristics for a long time, and is composed of a base metal containing nickel (Ni) as the main component and an alkaline earth metal oxide containing barium on the base metal. Consists of a layer of rare-earth metal oxide electron-emitting material, it is used for television cathodes operating under high current densities of 1.32 A / cm 2 to 2.64 A / cm 2.

In addition, the negative electrode disclosed in Japanese Patent Laid-Open No. 59-020941 has the purpose of reducing the thickness of the metal gas to prevent the movement of the negative electrode, preventing the depletion of the active metal during the lifetime of the negative electrode, and preventing the decrease of the strength of the base metal. Lanthanum (La) is contained in the form of LaNi ₅ and La ₂ O _{3 in} the base metal.

Further, US Application of Surface Science 2 (1979) page 173-186 shows a cathode formed by pressurizing a mixed powder of tungsten (W) and Ba ₃ Sc ₄ O ₉ by A.van Oostrom et al.

In addition, German Patent Publication No. 2626700 discloses an electron-emitting material for a high-pressure discharge lamp made of alkaline earth metal oxides such as BaO and tungsten oxide or a mixture of molybdenum (Mo) and rare earth metal oxides.

In addition, British Patent No. 1592520 shows an electron-emitting material layer for a discharge lamp in which Ba _2-X Sr _X CaWO _v (X = 0-0.5) is added to BeO and Y ₂ O ₃ .

Here, according to the cathode disclosed in Korean Unexamined Patent Publication No. 10-1987-0001629 and related Japanese Patent Application Laid-Open Nos. 5-266783 and 7-211222, the rare earth metal in the electron-emitting material layer Since the oxide reacts with alkaline earth metal oxides such as Sc ₂ O ₃ and BaCO ₃ and BaO to prevent oxidation of the gas metal, magnesium (Mg), silicon (Si), etc., which are active metals have It is described that it easily diffuses into the electron emitting material layer without forming a high-resistance oxide layer as a reactant in the vicinity thereof, which is represented by the following chemical formula.

BaCO ₃ = BaO + CO ₂ (5)

2Ni + CO ₂ = 2NiO + C (nickel surface) (6)

Sc ₂ O ₃ + ₃ CO ₂ = Sc ₂ (CO ₃ ) ₃ (electroradioactive material) (7)

BaO = Ba + O (8)

Ni + O = NiO (nickel surface) (9)

3Ba + 3O + 2Sc ₂ O ₃ = Ba ₃ Sc ₄ O ₉ (electroradioactive material) (10)

However, the negative electrode disclosed in the above cited documents should be subjected to high temperature heat treatment in a reducing atmosphere of 800 ° C. or higher before mixing the rare earth metal oxide with the alkaline earth metal oxide, and the rare earth metal oxide is sufficiently dissolved in the alkaline earth metal oxide suspension. Since the rare earth metal oxide should be included in the electron emitting material layer in a large amount, and because of this, the rare earth metal oxide is unevenly dispersed in the electron emitting material layer, so that the electron radiation characteristics are not uniform. Remains.

Meanwhile, the cathode for an electron tube disclosed in Korean Patent Laid-Open Publication No. 10-1999-0039660 (Application No. 10-1997-0059829) has a base metal containing nickel as a main component and an alkaline earth metal containing barium on the base metal. An electron-radiating material layer containing at least one of 0.0005 to 15% by weight of actinoid-based metal or 0.001 to 20% by weight of actinoid-based metal compound as the main component, and is disclosed in Korea Patent Publication No. 10-1999- 0009036 (Application No. 10-1997-0031298) uses an nitrate-based nitrate-based metal compound which is well soluble in an alkaline earth metal oxide suspension to further enhance the effect of electron radiation characteristics.

In addition, the cathode disclosed in Korean Laid-Open Patent Publication No. 10-1999-0039660 is operated under a high current density of 3.75 A / cm 2 by suppressing coarsening of electron-emitting materials by high temperature and residual gas during long time operation. Also in the cathode for an electron tube, it confirmed that it showed the stable electron emission characteristic for a long time.

However, the nitrate chemical group in the actinic nitrate-based metal compound included in the above-described negative electrode is not completely dissolved when the chemical group is different from the solvent of the nitrocellulose adhesive, which is the main component of the adhesive contained in the alkaline earth metal oxide suspension. There is a problem.

The present invention has been made to solve the above problems, and an object of the present invention is to prevent the oxidation of gaseous metals to improve dissolution of the metal compound, which serves to improve the electron-spinning characteristics of the cathode. By forming the same chemical group of the adhesive solvent and the chemical compound of the metal compound to dissolve the same, and further comprising a conductive metal to improve the conductivity of the electron-emitting material in the electron-emitting material layer, it is possible to significantly improve the electron radiation characteristics The present invention provides a cathode for an electron tube.

1 is a cross-sectional view showing a cathode for an electron tube according to the prior art.

2 is a cross-sectional view showing a cathode for an electron tube according to an embodiment of the present invention.

3 is a cross-sectional view showing a cathode for an electron tube according to another embodiment of the present invention.

*** Explanation of symbols for the main parts of the drawing ***

11: electrospinning material layer 12: heater

15: base metal 16: sleeve

111: coating layer

Electron tube cathode of the present invention for achieving the above object is a base metal containing nickel as a main component, an adhesive to adhere on the base metal, an adhesive solvent for dissolving the adhesive and the adhesive so as to be dissolved in the adhesive solvent And an electron-emitting material layer coated with an alkaline earth metal oxide suspension mixed with a metal compound composed of the same chemical group as the chemical group of the solvent.

In addition, the alkaline earth metal oxide suspension is characterized in that it further comprises a conductive metal to improve the conductivity of the electron-emitting material.

In addition, the cathode for an electron tube of the present invention for achieving the above object is a coating layer made of a base metal containing nickel as a main component, and an alkali earth metal oxide located between the base metal and the electron emitting material layer and containing barium. And an alkali earth metal oxide suspension mixed with an adhesive for adhering on the coating layer, an adhesive solvent for dissolving the adhesive, and a metal compound composed of the same chemical group as the chemical group of the adhesive solvent to dissolve in the adhesive solvent. It characterized in that it comprises an electron emitting material layer.

In addition, the coating layer and the alkaline earth metal oxide suspension is characterized in that it further comprises a conductive metal to improve the conductivity of the electron-emitting material.

Hereinafter, a cathode for an electron tube according to the present invention will be described with reference to the accompanying drawings.

As shown in FIG. 2, the cathode for an electron tube according to the exemplary embodiment of the present invention has a cylindrical sleeve 16 in which a heating heater 12 is inserted therein, and a main component of nickel is formed on top of the sleeve 16. Ni), as well as a base metal 15 containing a trace amount of a reducing agent such as silicon (Si), magnesium (Mg), and barium (Ba) as a main component on the base metal 15, In addition, it is composed of an electron emitting material layer 11 composed of an electron emitting material made of alkaline earth metal oxides such as strontium (Sr) and calcium (Ca).

The electron emitting material layer 11 is made by applying an alkaline earth metal oxide suspension on the base metal 15, and the alkaline earth metal oxide suspension is an alkali earth metal oxide containing barium and the electron emitting material layer. An adhesive for adhering (11) onto the base metal 15, an adhesive solvent for dissolving the adhesive, and a metal compound having the same chemical group as the adhesive solvent to dissolve in the adhesive solvent are included.

In addition, the alkaline earth metal oxide suspension further includes a conductive metal to improve conductivity of the electron-emitting material.

The adhesive is mainly composed of nitrocellulose, and the adhesive solvent includes at least one chemical group of acetate, oxalate, and carbonate. Examples of the adhesive solvent include butyl acetate ( butyl acetate, diethyl oxalate, and at least one of dimethyl carbonate.

The metal compound serves to improve the electron emission characteristics of the cathode by preventing the oxidation reaction of the base metal 15, the metal of the metal compound includes at least one of the rare earth metal and actinoid-based metal, At least one chemical group of acetate, oxalate, and carbonate is included to have the same chemical group as the adhesive solvent.

The conductive metal includes at least one of nickel (Ni), tungsten (W), molybdenum (Mo), tantalum (Ta) and rhenium (Re), and has a needle shape different in diameter and length.

The conductive metal has a needle shape to increase the probability of overlap in the electron-emitting material layer 11, and the diameter is preferably 5 microns (µm) or less and 50 microns (µm) or less in length. This is because when the diameter of the conductive metal is increased to 5 microns (μm) or more, the weight of the conductive metal in the electron-emitting material layer 11 is increased, and when the weight of the conductive metal is increased, the electron-emitting material layer is thereby caused. This is because the activation time of (1) becomes longer, and the disadvantage is that when the length of the conductive metal exceeds 50 microns (μm), an alkaline earth metal oxide suspension is sprayed using a spray gun to the base metal 15. This is because, in the process of coating and attaching to the upper surface, it may fail to pass through the nozzle of the spray gun or protrude outside the electron-emitting material layer 11.

In addition, the conductive metal is preferably formed in the electron-emitting material layer 11 to 0.3 wt% or more and 30 wt% or less. This is because when the content of the conductive metal is less than 0.3% by weight, the probability of overlapping the conductive metal is less effective, and when the content of the conductive metal is more than 30% by weight, the activation of the electron-emitting material layer 11 is caused. There are disadvantages such as longer time.

The cathode for an electron tube according to an embodiment of the present invention configured as described above is manufactured by the following process.

First, the alkaline earth metal oxide suspension is applied onto the base metal 15, and the alkaline earth metal oxide suspension is an alkaline earth metal oxide including barium (Ba), that is, barium (Ba) and strontium (Sr). And a binary or ternary oxide of calcium (Ca), an adhesive for bonding the electron-emitting material layer 11 on the base metal 15, for example, a nitrocellulose butyl acetate solution, and the like. In addition, the metal compound dissolved in the adhesive solvent, for example scandium acetate (scandium acetate) is made by adding and mixing in a small amount by weight.

The alkaline earth metal oxide suspension prepared as described above is applied on the base metal 15 to a thickness of about 60-100 μm by spraying or the like.

The subsequent process is heated by the heater 14 in the vacuum exhaust process of the electron tube as in the prior art, and the alkaline earth metal carbonate is converted into alkaline earth metal oxide and a part of the oxide is reduced and activated.

In such a cathode for an electron tube according to an embodiment of the present invention, the metal compound dissolved in the solvent of the adhesive is at least the same chemical group as the solvent of the adhesive for bonding the alkaline earth metal oxide on the base metal 15 Since the metal compound has the same chemical group as the solvent of the adhesive, the metal compound is sufficiently dissolved in the alkaline earth metal oxide suspension, so that the role of the metal in the metal compound in the alkaline earth metal oxide is sufficient. It is possible to further improve the electron emission characteristics of the cathode. Such a state is represented by the formula:

_{CH 3 COOC 4 H 9 + (} CH 3 COO) 3 Sc = 4CH 3 COO - + C 4 H 9 + + Sc + (11)

Equation (11) is a dissolution reaction of a metal compound having the same chemical group as that of the adhesive solvent, that is, butyl acetate, that is, scandium acetate, and a metal such as scandium (Sc) in the metal compound is rare earth metal as in the conventional negative electrode. And at least one of actinoid-based metals, and at least one of scandium (Sc), yttrium (Y), lantanium (La), and cerium (Ce) among the rare earth metals. In addition, at least one of actinium (actinium, Ac), thorium (thorium, Th), and protactinium (Pa) among the actinoid-based metals may maximize the effect.

In the rare earth metal compound, the rare earth metal sufficiently dissolved and dissolved in the electron-emitting material layer 11 reacts with alkaline earth metal oxides such as scandium (Sc) with BaCO 3 and BaO to oxidize the gas metal 15. This is because magnesium, silicon, and the like, which are activated metals, can easily diffuse into the electron-emitting material layer 11 without forming a high-resistance oxide layer at or near the grain boundary of the base metal 15. If expressed as:

BaCO₃ = BaO + CO₂ (12)

BaO = Ba + O (13)

2Ni + CO₂ = 2NiO + C, Ni + O = NiO (nickel surface) (14)

4Sc + 3CO₂ + 6O = Sc2 (CO₃) ₃ + Sc₂O₃ (electro-radioactive material) (15)

2Sc + 3O = Sc₂O₃

3Ba + 3O + 2 Sc₂O₃ = Ba₃Sc₄O ₉ (electroradioactive material) (17)

In the case of the actinoid compound, like the rare earth metal compound, the alkaline earth metal sufficiently dissolved and dissolved in the electron emitting material layer 11 reacts with the alkaline earth metal oxide, for example, thorium (Th) with BaCO 3 and BaO. Since the oxidation reaction of the base metal 15 is prevented, magnesium, silicon, and the like, which are active metals, are easily formed into the electron-emitting material layer 11 without forming a high-resistance oxide layer at or near the grain boundary of the base metal 15. By allowing it to be diffused, the electron emission characteristics of the cathode are improved.

Particularly, when the actinoid compound is contained, it exhibits stable electron emission characteristics for a long time in an electron tube cathode operated at a higher current density by suppressing high temperature during the long time operation of the cathode and coarsening of the electron emitting material due to residual gas.

Here, metal compounds such as rare earth metal compounds or actinoid compounds dissolved in the solvent of the adhesive have an effect when an amount of 0.0003% by weight or more and 15% by weight or less is contained in the electron-emitting material layer 11. It exhibits good properties, and if it contains more than 15% by weight, there is a problem such that the activation time of the electron-emitting material layer 11 is long.

The effect of improving the electron radiation characteristics even when containing a very small amount of the metal compound is that the metal compound has at least one chemical group as the solvent of the adhesive for bonding the alkaline earth metal oxide on the base metal 15. This is because it is sufficiently dissolved in the alkaline earth metal oxide suspension.

Meanwhile, a cathode for an electron tube according to another embodiment of the present invention will be described with reference to FIG. 3. Hereinafter, the same reference numerals are given to the same parts as the cathode for an electron tube according to the embodiment of the present invention.

In the cathode for an electron tube according to an embodiment of the present invention, if the metal in the metal compound in the electron-emitting material layer 11, for example, scandium (Sc) or the like is excessively excessive, the grain boundary of the base metal 15 during the cathode operation or In the vicinity, the reactant between the electron-emitting material layer 11 and the activating metal in the base metal 15 is hardly formed, so that the adhesion between the base metal 15 and the electron-emitting material layer 11 decreases significantly. This adverse effect is generated, and the lowering of the adhesive force may cause the electron-emitting material layer 11 to fall off from the base metal 15.

Therefore, the cathode for an electron tube according to another embodiment of the present invention is to compensate for the adhesion between the electron-emitting material layer 11 and the base metal 15 in the anode of the embodiment of the present invention. An anode for an electron tube according to another embodiment includes a base metal 15 containing nickel as a main component, a coating layer 111 formed on the base metal 15 and an alkali earth metal oxide containing barium, and the coating layer. An alkaline earth metal oxide containing barium (Ba) on the 111 and an alkali earth metal oxide are mixed with an adhesive and an adhesive solvent for bonding the alkaline earth metal oxide on the base metal 15 and a metal compound dissolved in the adhesive solvent. It consists of the electrospinning material layer 11 which apply | coated and attached the alkaline-earth metal oxide suspension.

The cathode for an electron tube according to another embodiment of the present invention, between the base metal 15 and the coating layer 11, the electron emitting material layer at or near the grain boundary of the base metal 15 during operation of the cathode. The reactant between the alkaline earth metal oxide of (11) and the activated metal in the base metal (15) is generated, and thus the adhesion between the base metal (15) and the electron-emitting material layer (11) is compensated for by using the reactant. I'm making it.

In addition, the cathode for the electron tube according to another embodiment of the present invention further includes a conductive metal for improving the conductivity of the electron emitting material in the coating layer 111, the conductive metal in the coating layer 111 is the electron emitting material layer. (11) at least one of nickel (Ni), tungsten (W), molybdenum (Mo), tantalum (Ta), and rhenium (Re), which are the same as the conductive metal in (11), the diameter of which is 5 microns (μm) or less and the length thereof Has a needle shape of 50 microns (μm) or less, and the conductive metal is effective when an amount of 0.3 wt% or more and 30 wt% or less is included in the coating layer 11.

Referring to the manufacturing process of the cathode for an electron tube according to another embodiment of the present invention as follows.

First, the base metal 11 and a coating layer 111 of an alkaline earth metal oxide containing at least barium on the base metal 11 are applied and applied, and on the coating layer 111, one embodiment of the present invention is applied. The electron emitting material layer 11 which is comprised similarly to the example is apply | coated and attached.

The subsequent process is heated by the heater 14 during the vacuum exhaust process of the electron tube as in one embodiment of the present invention, and the alkaline earth metal carbonate is converted to alkaline earth metal oxide and the oxide part is reduced to be activated.

As described above, the cathode for an electron tube according to the present invention has a high resistance that is a reactant between an alkali earth metal oxide included in an electron radiating material layer and an activation element included in a gas metal at or near the gas metal grain boundary during operation of the cathode. A layer oxide is formed, which prevents the diffusion of the active element in the gas metal into the electron emitting material layer and suppresses coarsening of the electron emitting material by residual gas generated during the reaction. It is applied to an electron tube used for operating a TV or a monitor, which has an effect of exhibiting stable electrospinning characteristics for a long time.

As described above, the negative electrode according to the present invention prevents the oxidation reaction of the gas metal and improves the electron emission characteristics of the negative electrode, so that the chemical compound of the adhesive solvent dissolving the adhesive can be sufficiently dissolved in the alkaline earth metal oxide suspension. By forming a group and a chemical group of the metal compound in the same manner, and by further including a conductive metal to improve the conductivity of the electron-emitting material in the electron-emitting material layer, there is an effect of remarkably improving the electron emission characteristics and the negative electrode according to the present invention Is applicable to cathode ray tube, photographing tube, transmitting tube, discharge tube and so on.

Claims (23)

A base metal containing nickel as a main component; Applying and applying an alkali earth metal oxide suspension in which an adhesive adhering on the base metal, an adhesive solvent for dissolving the adhesive, and a metal compound composed of the same chemical group as the chemical group of the adhesive solvent are dissolved so as to dissolve in the adhesive solvent. Electron tube cathode, characterized in that it comprises a layer of electron emitting material. The cathode of claim 1, wherein the alkaline earth metal oxide suspension further comprises a conductive metal to improve conductivity of the electron-emitting material. The cathode of claim 2, wherein the conductive metal comprises at least one of nickel (Ni), tungsten (W), molybdenum (Mo), tantalum (Ta), and rhenium (Re). The cathode for an electron tube according to claim 2, wherein the conductive metal has a diameter of 5 microns or less. The cathode for an electron tube according to claim 2, wherein the conductive metal has a length of 50 microns or less. 3. The cathode for an electron tube according to claim 2, wherein the conductive metal is contained in an amount of 0.3 to 30% by weight in the electron emitting material layer. The cathode of claim 1, wherein the alkaline earth metal comprises at least one of strontium (Sr) and calcium (Ca). The cathode for an electron tube according to claim 1, wherein the adhesive contains nitrocellulose as a main component. The cathode for an electron tube according to claim 1, wherein the adhesive solvent includes at least one chemical group of acetate, oxalate, and carbonate. The negative electrode for an electron tube according to claim 1, wherein the adhesive solvent comprises at least one of butyl acetate, dimethyl oxalate, and dimethyl carbonate. The cathode for an electron tube according to claim 9, wherein the metal compound includes at least one chemical group of acetate, oxalate, and carbonate. The cathode for an electron tube according to claim 1, wherein the metal of the metal compound contains at least one of a rare earth metal and an actinoid metal. The cathode of claim 12, wherein the rare earth metal in the metal compound includes at least one of scandium (Sc), yttrium (Y), lanthanum (La), and cerium (Ce). The cathode for an electron tube according to claim 12, wherein the actinoid-based metal in the metal compound includes at least one of actinium (Ac), thorium (Th), and float actinium (Pa). The cathode for an electron tube according to any one of claims 13 to 14, wherein the metal of the metal compound contains 0.0003 to 15% by weight in the electron emitting material layer. A base metal containing nickel as a main component; A coating layer formed between the base metal and the electron-emitting material layer and composed of an alkali earth metal oxide containing barium; Applying an adhesive to the coating layer, an adhesive solvent for dissolving the adhesive, and an alkali earth metal oxide suspension mixed with a metal compound composed of the same chemical group as the chemical group of the adhesive solvent to dissolve in the adhesive solvent. Cathode for an electron tube, characterized in that it comprises an electron emitting material layer. The cathode of claim 16, wherein the coating layer and the alkaline earth metal oxide suspension further include a conductive metal to improve conductivity of the electron emitting material. 18. The cathode for an electron tube according to claim 17, wherein the conductive metal has a diameter of 5 microns or less. 18. The cathode of claim 17, wherein the length of the conductive metal is less than 50 microns. The cathode for an electron tube according to claim 16, wherein said adhesive is based on nitrocellulose. The negative electrode of claim 16, wherein the adhesive solvent includes at least one chemical group of acetate, oxalate, and carbonate. 22. The negative electrode of claim 21, wherein the adhesive solvent comprises at least one of butyl acetate, diethyl oxalate, and diethyl carbonate. The cathode for an electron tube according to claim 16, wherein the metal compound includes at least one chemical group of acetate, oxalate, and carbonate.