KR100268243B1 - Cathod used in an electron gun - Google Patents

Abstract

PURPOSE: A cathode for electron gun is provided to obtain a long life time under a load with a high current density by securing a spreading path of a reducing agent included in a base metal in order to generate smoothly glass barium atoms. CONSTITUTION: A cathode for electron gun is installed on an upper opening of a sleeve(2) including a heater(4). The cathode for electron gun comprises a base metal(6). The base metal(6) of a cap shape includes elements such as Ni, Si, and Mg. A metal layer(12) is formed on an upper portion of the base metal(6). The metal layer(12) is formed with a pure Ni or Ni-Zr. An electron emission material layer is formed on the metal layer(12).

Description

Cathode for electron gun {Cathod used in an electron gun}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cathode for an electron gun used in a cathode ray tube, and more particularly to an anode for an electron gun that ensures a diffusion path of a reducing element contributing to the generation of free Ba atoms, thereby realizing long life under high current density loads.

A cathode ray tube is an apparatus for accelerating electrons emitted from an electron gun to a high voltage and landing on a phosphor of a screen, thereby realizing an image by excitation emission of the phosphor.

6 shows a general structure of a cathode for an electron gun used in such a cathode ray tube to emit electrons. In the figure, the heater 4 is installed inside the sleeve 2, and the upper portion thereof has a cap-like structure containing nickel (Ni) as a main component and a small amount of reducing elements such as silicon (Si) and magnesium (Mg). A base metal 6 is provided, on which an electron-emitting material layer 8 containing at least an alkali earth metal oxide containing barium as a main component is formed.

The oxide cathode configured as described above causes the metal oxide and the reducing element to react with the heat generated from the heater as an energy source, and the hot electrons are released using the generated free barium atoms. The electron emission capability in the electron gun cathode is determined by the supply amount of free barium atoms present in the metal oxide.

In recent years, however, cathode ray tubes have become increasingly finer and larger in size, and thus, it is necessary to develop cathodes capable of supplying free barium atoms for a long time at high current densities.

Accordingly, Korean Patent Application Publication No. 96-15634, previously filed by the applicant, discloses a lanthanum (La) compound and a magnesium (Mg) compound simultaneously or a La-Mg compound in an electron-emitting material layer containing an alkaline earth metal oxide. Disclosed is a cathode in which a compound is further contained, thereby suppressing evaporative consumption of free barium atoms.

However, the conventional cathode described above has a high current density of 2 to 3 A / cm 2 since the intermediate layer 10, which is a reaction product, is formed at the interface between the base metal 6 and the electron-emitting material layer 8 as shown in detail in FIG. 7. This results in shortened life at the load.

The intermediate layer 10 is produced by the reaction of barium oxide pyrolyzed in a metal oxide barium carbonate and a reducing agent silicon and magnesium to generate free barium atoms contributing to electron emission.

The free barium atoms generated by the reaction schemes 1 and 2 contribute to the electron emission, but reactants such as MgO and Ba ₂ SiO ₄ are generated to form a boundary between the base metal 6 and the electron emission material layer 8. The intermediate layer 10 is formed.

The intermediate layer 10 thus formed becomes a barrier to prevent late diffusion of the reducing agent contained in the base metal 6, thereby making it difficult to generate reactions of the free barium atoms requiring the reducing agent, thereby shortening the lifetime of the negative electrode. will be. In addition, since the intermediate layer 10 has a high resistance, there is a problem of limiting the dischargeable current density by disturbing the flow of the electron emission current.

On the other hand, Japanese Patent Application Laid-Open No. 3-257735 forms a metal layer mainly composed of tungsten, which has a reducing property which is equal to or lower than that of silicon or magnesium, and which is larger than nickel, between the base metal and the electron-emitting material layer. A cathode for an electron tube, in which a rare earth metal oxide is included in the electron-emitting material layer, the reaction product is decomposed by the rare earth metal oxide, and the reducing element of the metal layer contributes to the generation of free barium atoms.

However, the above-described negative electrode creates additional reaction products at the same time as the generation of free barium atoms, and shows a stable characteristic at the beginning of use, but has a problem in that the service life rapidly decreases with time.

Accordingly, the present invention aims to secure a late diffusion path of the reducing agent contained in the base metal to smoothly achieve the generation of free barium atoms, thereby realizing long life under high current density loads.

As a means for realizing the above object, the present invention forms a metal layer of nickel or nickel-zirconium as a main component on top of a base metal containing nickel as a main component and containing at least one type of reducing element, and at least on top of the metal layer. A cathode for an electron gun in which an electron-emitting material layer containing an alkali earth metal oxide containing barium is formed is proposed.

Here, the metal layer, which is the object of the present invention, is obtained by applying nickel or nickel-zirconium to the upper part of the base metal and heat-treating it or by depositing nickel or nickel-zirconium powder, and having a smaller particle size than the average particle of the base metal. It is formed to have.

The present invention also provides a structure in which a second electron emission material layer including at least a lanthanum compound and a magnesium compound or a lanthanum-magnesium composite compound is further formed on the alkali earth metal oxide including at least barium. It may include.

Based on the above configuration, in the present invention, the metal layer formed of particles smaller than the particles of the electron-emitting material layer effectively disperses the intermediate layer as a reaction product, thereby preventing the formation of the intermediate layer, which is a high resistance layer, and reducing the path of the reducing element. Since it contributes to late diffusion, the formation reaction of the free barium atoms required by the reducing element is continuously maintained to achieve long life at a high current density load of 2 to 3 A / cm 2.

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

Figure 2 is an enlarged cross-sectional view showing the main portion according to an embodiment of the present invention.

3 is a view showing the life characteristics according to another embodiment of the present invention.

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

5 is a view showing the life characteristics according to another embodiment of the present invention.

6 is a cross-sectional view showing a conventional cathode for electron guns.

7 is an enlarged cross-sectional view of a conventionally known cathode.

<Explanation of symbols for main parts of drawing>

6: base metal 8: electron emission material layer

10: intermediate layer 12: metal layer

80: second electron emitting material layer

Hereinafter, preferred embodiments for realizing the present invention will be described with reference to the accompanying drawings. For reference, in describing the present invention, the same reference numerals are used for the same parts as the components described through the drawings cited in the related art.

Example 1

In FIG. 1, the cathode for an electron gun, which is an embodiment of the present invention, is installed at an upper opening of a sleeve 2 in which a heater 4 is installed therein, and contains Ni as a main component and a small amount of reducing elements such as Si and Mg. A base metal 6 on the cap.

A _tertiary carbonate having (Ba.Sr.Ca) CO ₃ , which is an alkaline earth metal oxide containing at least Ba, on top of the base metal 6 is formed of pure Ni or Ni-Zr, or An electron-emitting material layer 8 made of (Ba.Sr) CO ₃ binary carbonate is formed.

In the present embodiment, the reaction product of BaO, Si, and Mg accumulated in the interface between the base metal 6 and the electron-emitting material layer 8 during the generation of free Ba atoms is dispersed. The metal layer 12 made of pure Ni or Ni-Zr is formed.

As shown in FIG. 2, the metal layer 12 of the present embodiment is formed to have a smaller particle size than the average particle of the base metal 6 so that the diffusion path itself of the reducing element contained in the base metal 6 is formed. This causes the reaction of BaO, Si, and Mg to occur in various places in the particles of the metal layer 12, and the intermediate layer 10, which is the reaction product, is dispersed to suppress accumulation, and the reducing element Si In other words, the diffusion of Mg facilitates the formation of free Ba atoms. In addition, the metal layer 12 is made of the same component as the base metal 6 by pure Ni or Ni-Zr, and thus does not produce an intermediate layer that is a reaction product unlike the conventional metal layer coated with W.

To this end, the metal layer 12, which is the object of the present embodiment, forms Ni or Ni-Zr at a thickness of 200 to 20,000 kPa on the upper part of the base metal 6 by sputtering, which is inert atmosphere or vacuum. It is obtained by heat-treating at 700-1,100 degreeC in atmosphere, and making alloying and diffusion between the base metal 6 and the metal layer 12.

The thickness of the metal layer 12 is preferably 200 to 20,000 Pa, but when the thickness is 200 Pa or less, the thickness is too small to secure a path of the reducing element, and when the thickness is 20,000 Pa or more, the diffusion of the reducing element is rather hindered. On the other hand, the thickness of the metal layer 12 according to the present embodiment is 3,000 to 10,000 kPa in the best embodiment.

On the other hand, the metal layer 12 of the present embodiment can be obtained by depositing Ni or Ni-Zr powder on the base metal 6. At this time, the deposition method can be realized by physical, chemical, mechanical methods such as spray (spray) method, printing method, electrodeposition method and metal salt solution method.

The upper portion of the formed metal layer 12 is formed by forming a ternary carbonate or binary carbonate with a thickness of 20 to 80 μm by a conventional spraying method. The cathode of this embodiment should not have a total thickness of more than 200 μm. .

Example 2

The cathode for an electron gun, which is the second embodiment of the present invention, proposes a method of using the second electron-emitting material layer pre- filed by the applicant in place of the electron-emitting material layer of the first embodiment.

Referring to FIG. 1, the present embodiment will be described as an alkaline earth metal oxide containing at least Ba on a metal layer 12 made of pure Ni or Ni—Zr, wherein the ternary carbonate is (Ba · Sr · Ca) CO ₃ or ( The second electron emission material layer 80 in which the La compound and the Mg compound are simultaneously or the La-Mg complex compound is further formed in the binary carbonate of Ba · Sr) CO ₃ .

The La compound and the Mg compound or the La-Mg composite compound are used to suppress the evaporation of free Ba atoms so as to provide a continuous supply, and 0.01 to 1% by weight of the carbonate weight is most preferable. When driving, the evaporation suppression effect of the glass Ba atoms is insignificant, and when 1 wt% or more, electron emission characteristics may be reduced during initial driving.

Therefore, according to the present embodiment, in addition to the effective dispersing action of the intermediate layer 10 by the metal layer 12, the evaporation of free Ba atoms generated by the reaction of BaO, Si, and Mg is applied to the second electron emitting material layer 80. It is suppressed by this, and sintering of a metal oxide is prevented accordingly.

In the metal layer 12 according to the present embodiment, pure Ni or Ni-Zr is applied on the upper portion of the base metal 6 to a thickness of 200 to 20.000 kPa, and heat-treated in an inert atmosphere or a vacuum atmosphere, and the base metal 6 and It is obtained by alloying and diffusing between the metal layers 12. In addition, the metal layer 12 of this embodiment may be obtained by depositing Ni or Ni-Zr powder on the base metal 6.

The second electron emission material layer 80 including the La compound and the Mg compound simultaneously or the La-Mg complex compound in the ternary carbonate or binary carbonate is further sprayed to a thickness of 20 to 80 μm on the upper portion of the metal layer 12 thus formed. It is to realize the cathode of this embodiment, which is coated so that the total thickness does not exceed 200 mu m.

The result of having assembled the cathode for electron guns according to the present embodiment described above to the cathode ray tube and inspecting the life characteristics thereof is shown in FIG. In the figure, A is a cathode of this embodiment in which a carbonate contains 0.5 wt% of a La-Mg compound and the metal layer 12 has a thickness of 3,000 to 5,000 kPa. In addition, in the drawing, B is an oxide cathode including 0.5 wt% of a La-Mg compound in carbonate, which is pre- filed by the present applicant, and C in the drawing is a conventional oxide cathode.

The life test is a measurement of the amount of electron emission current measured under continuous operation for 6,000 hours, and is performed at a current of 2,000 to 3,000 μA per cathode.

As a result, it can be seen that the cathode for the electron gun according to the present embodiment has a much improved lifespan characteristic at high current compared to the prior arts B and C. Specifically, the present invention shows that 90% of the initial current value is maintained even after 6,000 hours under high current density operation.

Example 3

As shown in FIG. 4, in the cathode for the tank gun according to the third embodiment of the present invention, a metal layer 12 made of pure Ni or Ni-Zr is formed on an upper portion of the base metal 6, and at least Ba is formed thereon. An electron-emitting material layer 8 made of ternary carbonates or binary carbonates is formed, and on top of the ternary carbonates or binary carbonates containing at least Ba, La and Mg compounds are added simultaneously or La-Mg complex compounds are further included. 2, the electron-emitting material layer 80 is formed.

In this embodiment, the reducing element of Ni or Ni-Zr in the above-mentioned Example 2 promotes the reduction of the free Ba atoms together with the reducing elements contained in the base metal 6, so that the evaporation of the free Ba atoms proceeds excessively. Considering what you can do.

Therefore, this embodiment is a method of dispersing the reaction product of BaO and Si and Mg thermally decomposed in the carbonate accumulated at the interface between the base metal 6 and the electron-emitting material layer 8, the pure Ni between the interface Or metal layer 12 made of Ni-Zr.

In addition, the present embodiment is a method for suppressing the evaporative consumption of the free Ba atoms in the electron-emitting material layer (8), the La compound and Mg compound in the carbonate or La-Mg complex compound containing 0.01 to 1% by weight The second electron emitting material layer 80 is formed.

To this end, the target metal layer 12 of the present embodiment is a pure Ni or Ni-Zr is applied to the upper portion of the base metal 6 to a thickness of 200 to 2,000 kPa, and heat-treated in an inert atmosphere or a vacuum atmosphere to base metal ( It is obtained by alloying and diffusing between 6) and the metal layer 12. Here, the thickness of the metal layer 12 according to the present embodiment is preferably 200 to 2,000 kPa in consideration of the thicknesses of the electron emitting material layer 8 and the second electron emitting material layer 80 formed thereon. In an embodiment, the thickness is 400-1,200 Hz.

On the other hand, the metal layer 12 of the present embodiment may be obtained by depositing Ni or Ni-Zr powder on the base metal 6.

The upper layer of the metal layer 12 is coated with an electron emitting material layer 8 made of ternary carbonate or binary carbonate with a thickness of 20 to 80 μm, and La compound and Mg compound are added to the ternary carbonate or binary carbonate. At the same time or by coating the second electron-emitting material layer 80 containing La-Mg composite compound to a thickness of 20 ~ 80㎛, it is possible to manufacture the cathode for the electron gun of this embodiment so that the total thickness does not exceed 200㎛ have.

The negative electrode for the electron gun according to the present embodiment described above was assembled to the cathode ray tube, and the result of inspecting its life characteristics is shown in FIG. 5. In the drawing, D represents a metal layer 12 having a thickness of 400 to 1,200 kPa, an electron-emitting material layer 80 formed thereon, and a La-Mg compound containing 0.5 wt% of carbonate in the upper portion thereof. Example cathode. In the drawings, E is a conventional oxide cathode.

The life test measures the amount of decrease in electron-emitting current under continuous operation for 6,000 hours, and is performed at a current of 2,000 to 3,000 μA per cathode.

As a result, the cathode for the electron gun according to the present invention can be seen that the life characteristics are significantly improved at a high current compared to the prior art. Specifically, the present invention shows that 95% of the initial current value is maintained even after 6,000 hours under high current density operation.

In addition, the cathode of the present invention shows a tendency that the maximum cathode current increases with a certain time more than the maximum cathode current (maximum current emitted from the cathode under constant driving conditions).

As can be seen through the embodiment described above, the electron gun cathode according to the present invention substantially solves the problems of the prior art.

That is, the present invention has a structure in which a metal layer made of fine particles is formed between a base metal containing a reducing element and an electron-emitting material layer made of carbonate, thereby dispersing the reaction product generated during generation of free Ba atoms and Since the late diffusion path is secured, release of free Ba atoms can be continuously realized.

In addition, the present invention provides a second electron emitting material layer containing the La compound and the Mg compound at the same time or La-Mg complex compound, or La compound and Mg compound at the same time or La-Mg complex compound in the electron emitting material layer Since it forms further, the evaporative consumption of free Ba atom can be suppressed.

Therefore, according to the present invention, since the release of free Ba atoms is continued by the interaction between the metal layer and the electron emission material layer or the second electron emission material layer and the evaporation consumption is suppressed, the life characteristics are maintained even at a high current density load of 2 to 3 A / cm 2. The effect can be improved.

In addition, although the oxide cathode of the present invention is well known to maintain long life at high current density, it is also possible to obtain the practicality of replacing the impregnated cathode, which is difficult to manufacture and expensive.

On the other hand, the present invention is not limited to the above-described specific preferred invention, and any person skilled in the art to which the present invention pertains can make various changes without departing from the gist of the present invention as claimed in the claims. It will be possible.

Claims (21)

Electron emission comprising a base metal containing nickel as a main component and containing at least one reducing element, a metal layer made of nickel as a main component formed thereon, and an alkaline earth metal oxide containing at least barium formed thereon Cathode for an electron gun comprising a material layer. The cathode for an electron gun according to claim 1, wherein the metal layer is made of nickel-zirconium. The cathode for an electron gun according to claim 1 or 2, wherein the metal layer is obtained by applying nickel or nickel-zirconium to the upper part of the base metal and heat-treating it. The cathode for an electron gun according to claim 3, wherein the metal layer is formed of particles smaller than the average particle size of the base metal. The negative electrode for an electron gun according to claim 1 or 2, wherein the metal layer is obtained by depositing nickel or nickel-zirconium powder on the base metal. The cathode for an electron gun according to claim 5, wherein the metal layer is formed of particles smaller than the average particle size of the base metal. The cathode for an electron gun according to claim 1, wherein the metal layer is formed to a thickness of 200 to 20,000 Pa. The cathode of claim 1, wherein the electron-emitting material layer further comprises a lanthanum compound and a magnesium compound or a lanthanum-magnesium composite compound. The cathode for an electron gun according to claim 8, wherein the metal layer is made of nickel-zirconium. The cathode for an electron gun according to claim 8 or 9, wherein the metal layer is obtained by applying nickel or nickel-zirconium to the upper part of the base metal and heat-treating it. The cathode for an electron gun according to claim 10, wherein the metal layer is formed of particles smaller than the average particle size of the base metal. The negative electrode for an electron gun according to claim 8 or 9, wherein the metal layer is obtained by depositing nickel or nickel-zirconium powder on the base metal. The cathode of claim 12, wherein the metal layer is formed of particles smaller than the average particle size of the base metal. The cathode for an electron gun according to claim 8, wherein the metal layer is formed to a thickness of 200 to 20,000 kPa. The method of claim 1, wherein the second electron emitting material layer obtained by forming a lanthanum compound and a magnesium compound simultaneously or a lanthanum-magnesium composite compound is further formed on the alkali earth metal oxide including at least barium on the upper portion of the electron emitting material layer. An electron gun cathode. The cathode for an electron gun according to claim 15, wherein the metal layer is made of nickel-zirconium. The cathode for an electron gun according to claim 15 or 16, wherein the metal layer is obtained by applying nickel or nickel-zirconium to the upper part of the base metal and heat-treating it. 18. The cathode of claim 17, wherein the metal layer is formed of particles smaller than the average particle size of the base metal. The negative electrode for an electron gun according to claim 15 or 16, wherein the metal layer is obtained by depositing nickel or nickel-zirconium powder on the base metal. 20. The cathode of claim 19, wherein the metal layer is formed of particles smaller than the average particle size of the base metal. The cathode for an electron gun according to claim 15, wherein the metal layer is formed to a thickness of 200 to 20,000 kPa.

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