KR20030090040A - A Cathode of Color Cathode Ray Tube - Google Patents

Abstract

PURPOSE: A cathode for color cathode ray tube is provided to lengthen a lifetime and emit stably electrons by forming a gaseous metal material and an electron radiation material layer with different components. CONSTITUTION: A cathode for color cathode ray tube includes a triode portion, a prefocus lens portion, and a main lens portion. The triode portion is formed with a plurality of cathodes for emitting electron beams, a control electrode for controlling the amount of the electron beams, and an accelerating electrode for accelerating the electron beams. The prefocus lens portion is formed with two or more electrodes. The main lens portion is formed with a focusing electrode for focusing the electron beams and an anode electrode. Each cathode include a gaseous metal material(37) and an electron radiation material layer(35). The gaseous metal material(37) is formed on a cylindrical sleeve(32) including a heater(34). The gaseous metal material(37) is composed of nickel as a principal component. The electron radiation material layer(35) is formed on the gaseous metal material(37). The gaseous metal material(37) is composed of barium oxide and strontium oxide.

Description

Cathode for color cathode tube {A Cathode of Color Cathode Ray Tube}

The present invention relates to a color cathode ray tube, and more particularly, a color that extends the life of the cathode and emits more electrons by varying constituent materials of the base metal and the electron emitting material layer forming the cathode for the color cathode ray tube. It relates to a cathode for a cathode ray tube.

Referring to the drawings in detail, as shown in FIG. 1, an inline electron gun for a cathode ray tube includes a first grid which is a common lattice of three independent cathodes 3 and three cathodes 3 spaced apart from the cathode. (4) and the second electrode 5, the third electrode 6, the fourth electrode 7, the fifth electrode 8, and the sixth electrode arranged at regular intervals from the first electrode 4 9), the shield cup having the BSC (Bulb Space Connector) 11 attached to the neck of the tube while electrically connecting the electron gun and the tube to the upper part of the sixth electrode 9 ( It is composed in the order of 10).

In addition, the electron gun is connected to a power source through a stem pin 1 and a heater 2 embedded in the cathode 3 emits electrons from the surface of the cathode, which is transferred to the first electrode 4 as a control electrode. The electron beam 13 is controlled by this, and the electron beam 13 is accelerated by the 2nd electrode 5 which is an acceleration electrode, the 2nd electrode 5, the 3rd electrode 6, the 4th electrode 7, and The electron beam is partially focused or accelerated by the shear focusing lens formed between the fifth electrodes 8 and further focused or focused by the focus electrode fifth electrode 8 and the anode electrode sixth electrode 9 which are the main lens forming electrodes. In addition, inner electrodes are embedded in the electrodes to freely control an electric field. In addition, passing through the shadow mask 14 provided at a predetermined interval on the inner surface of the screen 15 impinges on the fluorescent surface 17 to emit light.

In addition, a deflection yoke 12 for deflecting the electron beam 13 emitted from the electron gun to the entire screen 15 is located on the outer wall of the funnel of the cathode ray tube, thereby deflecting the electron beam 13 to the entire fluorescent surface 17. The center purity magnet 16 is installed to adjust the purity of the screen center.

FIG. 2 is a cross-sectional view of a conventional cathode for color cathode ray tube 3, a cylindrical sleeve 32 in which a cathode heating heater 34 is inserted in the cathode 3, silicon (Si), It contains a trace amount of reducing elements such as magnesium (Mg), the main metal is nickel (Ni), the main metal and the barium (Ba) on the upper portion of the base metal 31, and other strontium (Sr ) And an electron-emitting material layer 33 composed of alkaline earth metal oxides such as calcium (Ca).

Looking at the manufacturing method and technology of the conventional negative electrode 3 having the structure as described above are as follows.

First, a disc-shaped gaseous metal (31) containing a small amount of reducing elements such as silicon (Si) and magnesium (Mg) is contained on a cylindrical cylindrical sleeve 32 having a heater as a heating source of a cathode. Form. The base metal 31 contains 0.02 to 0.04% by weight of silicon (Si) as a reducing agent, and a very small amount of magnesium (Mg) as 0.035 to 0.065% by weight.

In addition, an alkaline earth metal oxide having a barium (Ba) oxide as a main component is formed on the base metal 31. An alkaline earth metal oxide composed of a ternary metal oxide represented by (Ba, Sr, Ca) O is an electron-emitting material. Layer 33 is formed.

The method of forming the electron emitting material layer is a suspension (suspension, suspension) form by mixing ternary carbonate (Triple Carbonation) consisting of (Ba, Sr, Ca) CO ₃ with an organic solvent such as nitrocellulose (Nitrocellulose) Make. Subsequently, the suspension is coated on the base metal by spraying or electrodeposition to form the electron-emitting material layer 33.

Thereafter, the cathode 3 manufactured as described above is mounted on an electron gun for use in a cathode ray tube, and then the electron gun is inserted into the cathode ray tube and subjected to an exhaust process of vacuuming the cathode ray tube while heating to about 600 °. When the cathode for the color cathode ray tube 3, which has undergone the exhaust process, is subjected to an activation process of heating to a high temperature of 900 to 1000 °, the electron-emitting material layer 33 has a semiconducting property. When a constant voltage is applied, electrospinning is performed. This is represented by the following scheme.

BaCO ₃ (heating) = BaO + CO _{2 ↑} ---------------- ①

4BaO + Si = 2Ba + Ba ₂ SiO ₄ ------------ ②

2BaO + Si = Ba + SiO ₂ ---------------- ③

BaO + Mg = Ba + MgO ------------------ ④

^{_{Ba = Ba 2 + + 2e -}} ( E generated) ----------- ⑤

In the process as described above, Ba ₂ SiO ₄ , SiO _2, etc. are formed at the boundary between the electron-emitting material layer 33 and the base metal 31 as shown in the reaction equations ②, ③, ④ during operation of the cathode 3. .

Therefore, since the reaction product thus formed becomes a barrier called an intermediate layer, magnesium (Si) or silicon (Si) of the gaseous metal prevents diffusion into the electron-emitting material layer 33 and free barium (Ba), which is an electron radiation source, Makes the production difficult. The intermediate layer thus results in shortening the lifetime of the oxide cathode.

In addition, this intermediate layer has a high resistance, which hinders the flow of electron emission and has a problem of limiting the current density.

In recent years, televisions and other devices using CRTs have increased demands for high current density and long-life cathodes according to the trend of high definition and enlargement. However, conventional cathodes (3) have an electron emission performance according to resistance and an intermediate layer. Due to the shortened lifetime of the negative electrode has a problem that does not meet these requirements.

Therefore, in order to solve such a problem, the research which extends the lifetime of an oxide cathode is performed conventionally.

For example, Japanese Patent Application Laid-Open No. 64-41137 describes a technique of improving the lifetime by containing Eu ₂ O ₃ , which is a rare earth metal oxide, in an existing electron-emitting material layer 33, and US Pat. No. 4,797,593 describes a rare earth metal. It has been reported to improve the life of the negative electrode by dispersing materials such as oxides Sc ₂ O ₃ , Y ₂ O ₃ in the existing ternary carbonate.

This indicates that the rare earth metal inhibits the interlayer formation and evaporation of the free barium, thereby increasing the lifetime of the cathode.

However, since the rare earth metal promotes sintering of the oxide at the operating temperature of the cathode, thereby reducing the amount of electrons released by reducing the reaction region with the reducing agent, the conventional cathode as described above has an amount of electron emission after a certain time has elapsed. This tends to fall suddenly.

In addition, the cathode described above has a poor cut off drift characteristic, which is measured on a screen and shows a change in the cathode voltage immediately before the electron beam exiting the cathode disappears, and has a small amount of gas present in the cathode ray tube. Due to the high reactivity, electron emission is poor.

In addition, in order to solve the above problems, a cathode for a color cathode ray tube having an actinium compound (a) added to the electron emitting material layer 33 has been proposed. However, in the case of the cathode, the lifespan decreases in the region of high current density, and as time passes, electron emission is not stabilized.

Accordingly, an object of the present invention is to solve the above-mentioned problems, and by varying the constituents of the gas metal and the electron-emitting material layer of the cathode for the color cathode ray tube, the lifetime is improved in a high current density region and the color is stable for a long time. The present invention provides a cathode for a cathode ray tube.

1 is a cross-sectional view of a typical cathode ray tube.

2 is a cross-sectional view of a cathode for a color cathode ray tube according to the prior art.

3 is a cross-sectional view showing a first embodiment of a cathode for a color cathode ray tube according to the technique of the present invention;

4 is a cross-sectional view showing a second embodiment of a cathode for a color cathode ray tube according to the technique of the present invention;

5 is a graph showing the maximum current (MIK) amount of the prior art and the present invention.

Figure 6 is a graph comparing the lifetime of the negative electrode of the prior art and the present invention.

7 is a graph comparing the cut-off drift characteristics of the prior art and the present invention.

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

3: cathode 4: first electrode

5: second electrode 13: electron beam

31, 37: base metal 32: sleeve

34: heater 33, 35, 36: electromagnetic radiation material layer

a: actinium group compound

The first technical solution of the present invention for achieving the above object is a three-pole portion consisting of a plurality of cathodes for emitting an electron beam, a control electrode for adjusting the radiation amount of the electron beam and an acceleration electrode for accelerating to the screen; A prefocus lens unit including at least two electrodes which focus a certain amount of the electron beam, a focusing electrode to which a focus voltage is applied to focus the electron beam on a screen, and an anode electrode to which an anode voltage is applied In the electron gun for a color cathode ray tube including a main lens portion, the cathode comprises a base metal mainly composed of nickel formed on a cylindrical sleeve incorporating a heater, and an electron emitting material layer composed of barium oxide and strontium oxide on the base metal. It is.

The second technical solution of the present invention is characterized in that the actinium compound is contained in the electron-emitting material layer.

Another technical solution of the present invention is characterized in that the base metal includes at least one of tungsten and magnesium.

And, preferably, a three-pole portion consisting of a plurality of cathodes for emitting an electron beam, a control electrode for adjusting the radiation amount of the electron beam and an acceleration electrode for accelerating to the screen, and at least two to serve to focus the electron beam a certain amount In the electron gun for color cathode ray tube comprising a prefocus lens unit consisting of the above electrodes, and a main lens unit consisting of a focusing electrode to which the focus voltage for focusing the electron beam on the screen and a positive electrode to which the anode voltage is applied, The cathode includes a gaseous metal mainly composed of nickel formed on a cylindrical sleeve incorporating a heater, and an electron-emitting material layer composed of an alkaline earth metal oxide mainly composed of barium oxide on the gaseous metal, wherein the gaseous metal includes tungsten and It is characterized by containing magnesium.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 and 4 are cross-sectional views of a cathode for a color cathode ray tube according to the present invention, a gas containing a small amount of reducing elements and having a main component of nickel (Ni) on an upper end of a cylindrical sleeve 32 in which a cathode heating heater 34 is inserted. Electron-emitting material composed of an alkaline earth metal oxide containing tungsten (W) and magnesium (Mg) in the metal 31 and a barium oxide, a strontium oxide, and an actinium compound (a) on the base metal 37. With layers 35 and 36.

The content of tungsten (W) contained in the base metal 37 is 0.1 to 10% by weight based on the entire base metal 37, and the content of magnesium (Mg) is based on the entire base metal 37 0.01 to 1% by weight.

In addition, the barium (Ba) of the alkaline earth metal oxide constituting the electron emission material layers 35 and 36 is 50 to 65% based on the alkaline earth metal oxide, and the strontium (Sr) is 35 to 50%. . The actinium compound (a) contained in the electron-emitting material layer 35 is composed of 0.001% by weight to 1% by weight.

In the present invention, a large amount of tungsten (W) and magnesium (Mg) contained in the base metal 37 can be used as a reducing agent to facilitate electron emission.

6BaO + W = 3Ba + Ba ₃ WO ₆ ------------ ⑥

Ba ₃ WO ₆ + 6Mg = 3Ba + W + 6MgO --------- ⑦

Tungsten (W) present in the gas metal 37 as in Scheme ⑥ reacts with barium oxide (BaO) to generate intermediate reactants of free barium (Ba) and Ba ₃ WO _{6, which} are electron-emitting sources, and again Reaction equation ⑦ As such, Ba ₃ WO ₆ as an intermediate reactant reacts with magnesium (Mg) as a reducing element to reduce free barium (Ba) and tungsten (W) again.

Since the produced tungsten (W) can be used as a reducing agent again, it is possible to smoothly generate free barium (Ba) for a long time to achieve a stable electron radiation.

In addition, the tungsten (W) contained in the base metal 37 is more preferably present in an amount of 1 to 5% by weight, so that the reaction with the electron emitting material layers 35 and 36, thermal expansion in nickel (Ni), and the like become stable. When the cathode is operated for a long time at high current density, the cut-off drift characteristic showing the change in the cut-off voltage immediately before the electron beam from the cathode disappears appears to be stable.

In addition, an alkaline earth metal oxide composed of barium (Ba) and strontium (Sr) is composed of a needle-like binary coprecipitation oxide of (Ba, Sr) O. The binary coprecipitation oxide is obtained by dissolving nitrates such as Ba (NO ₃ ) ₂ and Sr (NO ₃ ) ₂ in pure water and then coprecipitation using NaCO ₃ as precipitation.

The binary alkaline earth metal oxide obtained as described above has a lower number of singlet than the ternary alkaline earth metal oxide, which is a negative electrode 3 for a conventional color cathode ray tube. In addition, in the case of binary alkaline metal oxides composed of multiple bonds of barium oxide and strontium oxide, the density of bonding of barium (Ba) and strontium (Sr) oxides is barium (Ba), strontium (Sr), and calcium (Ca) oxide. Since the bonding strength of the binary oxide consisting of a combination of barium (Ba) and strontium (Sr) oxides is weaker than that of the ternary alkaline earth metal oxide, the added actinium compound ( a) is uniformly present in the electron-emitting material layers 35 and 36 made of binary alkaline earth metal oxides, and can easily react with them.

That is, the actinium compound (a) added not only functions as a reducing agent, but also inhibits the formation of an intermediate layer.

Therefore, at the same cathode temperature, not only can the current of the binary alkaline earth metal oxide be increased, but also the current density can be increased.

Embodiment 1 of the present invention is formed by the following method in the structure of a cathode as shown in FIG.

First, a base metal containing nickel (Ni) as a main component and containing tungsten (W) and magnesium (Mg) as reducing elements is prepared. That is, the base metal 37 is composed of a nickel alloy containing 3% by weight of tungsten (W) and 0.25% by weight of magnesium (Mg). The nitrates of Ba (NO ₃ ) ₂ , Sr (NO ₃ ) ₂ and Ca (NO ₃ ) ₂ are dissolved in pure water and then co-precipitated in the form of carbonate using Na ₂ CO ₃ to obtain co-precipitated ternary carbonates.

0.1 wt% of Th (NO ₃ ) ₄ -5H ₂ O, an actinium compound (a), is added to the ternary carbonate to form a mixture, and the mixture is mixed with an organic solvent such as nitrocellulose. To form a suspension (suspension).

Subsequently, the suspension is coated on the base metal by a spray method to form the electron emission material layer 35.

The cathode for the color cathode ray tube formed as described above is inserted and fixed in the electron gun, the electron gun is sealed in the bulb for the cathode ray tube, and then exhausted to form a vacuum, and the cathode for the color cathode ray tube subjected to the exhaust process is 900 to 1000. After the activation process of heating to a high temperature of ??, the electron-emitting material layer 35 has a semiconductor property, and then, when a constant voltage is applied to the electron gun, the electron emission is performed.

Another embodiment 2 of the present invention is a structure of the negative electrode as shown in Figure 4 is formed by the following method.

A base metal 37 composed of a nickel alloy containing nickel (Ni) as a main component and containing 3% by weight of tungsten (W) and 0.25% by weight of magnesium (Mg) is prepared. The nitrates of Ba (NO ₃ ) ₂ and Sr (NO ₃ ) ₂ are dissolved in pure water and then co-precipitated in the form of carbonate using Na ₂ CO ₃ to obtain co-precipitated binary carbonates.

0.1 wt% of Th (NO ₃ ) ₄ -5H ₂ O, an actinium compound (a), is added thereto to form a mixture, and mixed with an organic solvent such as nitrocellulose. To form a suspension. Subsequently, the suspension is coated on the base metal by a spray method to form the electron-emitting material layer 36. The cathode for the color cathode ray tube formed as described above is subjected to the above process so that electron radiation can be carried out.

After that, the cathode ray tube was completed by a usual manufacturing process to measure the initial electron emission amount. The initial electron emission characteristic is measured by the maximum current generated from the cathode under a certain driving condition, that is, the amount of current called MIK, and the cathode lifetime characteristic is evaluated as the residual rate at a given time with respect to the initial MIK.

That is, as shown in Figure 5, the maximum current and the MIK amount showing the initial electron emission characteristics, the cathode of Example 2 of the present invention has the largest value, the life cycle characteristics of Figure 6 in the graph showing the initial electron emission characteristics The lifetime characteristic, expressed as the residual current for a certain time with respect to the current amount, i.e., MIK, is expressed relative to the initial electron emission (MIK) value.

Therefore, as shown in FIG. 6, it can be seen that Example 1 of the present invention is superior to the conventional cathode, and Example 2 of the present invention exhibits superior characteristics than Example 1 of the present invention.

FIG. 7 is a graph showing cut off drift characteristics of the cathode 3 during long time operation. The cut off drift characteristic is measured on a screen, and the negative voltage immediately before the electron beam from the cathode disappears is called a cut off voltage, and the cut off voltage is changed over time. The change according to this is called a cut off drift characteristic. The smaller the amount of cutoff drift, the larger the amount of electron emission.

Therefore, FIG. 7 shows the cut off drift compared to an initial value, and in the case of the cathode of the present invention containing tungsten (W) and magnesium (Mg) in the base metal, the cut off drift is shown. It can be seen that the amount of is small and stabilizes over time.

As described above, it can be seen that the cathode of the present invention has a smaller amount of cut-off drift, longer life, and a greater amount of maximum current than the conventional cathode. In addition, the cathode of the present invention is not only useful for showing a high current density, but also can achieve stable electron radiation for a long time at a high current density.

Claims (9)

It consists of a three-pole portion consisting of a plurality of cathodes for emitting an electron beam, a control electrode for adjusting the radiation amount of the electron beam and an acceleration electrode for accelerating to the screen, and at least two or more electrodes that serve to focus the electron beam a certain amount An electron gun for a color cathode ray tube comprising a prefocus lens unit, a main lens unit comprising a focusing electrode to which a focus voltage for focusing the electron beam on the screen, and a cathode electrode to which an anode voltage is applied, The cathode is a cathode for a cathode ray tube comprising a gas metal mainly composed of nickel formed on a cylindrical sleeve containing a heater, and an electron emitting material layer composed of barium oxide and strontium oxide on the gas metal. The method of claim 1, A cathode for a cathode ray tube, characterized in that the actinium compound is contained in the electron-emitting material layer. The method of claim 1, The cathode for a cathode ray tube, characterized in that at least one of tungsten and magnesium in the base metal. The method of claim 1, Alkaline earth metal oxide constituting the electron emitting material layer is a negative electrode for a color cathode ray tube, characterized in that the proportion of barium is 50 ~ 65%. It consists of a three-pole portion consisting of a plurality of cathodes for emitting an electron beam, a control electrode for adjusting the radiation amount of the electron beam and an acceleration electrode for accelerating to the screen, and at least two or more electrodes that serve to focus the electron beam a certain amount An electron gun for a color cathode ray tube comprising a prefocus lens unit, a main lens unit comprising a focusing electrode to which a focus voltage for focusing the electron beam on the screen, and a cathode electrode to which an anode voltage is applied, The cathode includes a gaseous metal mainly composed of nickel formed on a cylindrical sleeve including a heater, and an electron-emitting material layer composed of an alkali earth metal oxide containing barium oxide as a main component on the base metal. A negative electrode for a color cathode ray tube, characterized in that tungsten and magnesium are contained in the base metal. The method of claim 5, The base metal is a negative electrode for a color cathode ray tube, characterized in that the content of tungsten 0.1 to 10% by weight based on the base metal. The method of claim 5, The base metal is a negative electrode for a color cathode ray tube, characterized in that the magnesium content of 0.01 to 1.0% by weight based on the base metal. The method of claim 5, The electron-emitting material layer is a negative electrode for a color cathode ray tube, characterized in that it comprises at least one of barium oxide, strontium oxide, calcium oxide, actinium compound. The method of claim 5, Alkaline earth metal oxide constituting the electron emitting material layer is a negative electrode for a color cathode ray tube, characterized in that the proportion of barium is 50 ~ 65%.