JPH1092293A - Electron tube cathode - Google Patents

Abstract

(57) Abstract: An electron tube cathode capable of suppressing the formation of an intermediate material layer formed at an interface between a metal substrate and an electron emitting material layer and exhibiting stable electron emission characteristics for a long time under a high current density state. I will provide a. SOLUTION: A cap-shaped metal base 2 containing nickel (Ni) as a main component and containing a trace amount of a reducing metal element such as silicon (Si) and magnesium (Mg); And a donut-shaped thin film region 3 containing a reducible metal element on the surface of the cap-shaped metal substrate 2 in the electron tube cathode having an electron-emitting material layer 4 made of an alkaline earth metal oxide containing barium (Ba). . By forming the donut-shaped thin film region 3, the formation of an intermediate material layer at the interface between the cap-shaped metal substrate 2 and the electron-emitting material layer 4 is suppressed, and even if the device operates in a high current density state, it will be used for a long time. Stable electron emission characteristics are maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron tube cathode, and more particularly, to an electron tube cathode configured to exhibit high electron emission characteristics in a stable state for a long period of time.

[0002]

2. Description of the Related Art Conventionally, a cathode used for an electron tube such as a cathode ray tube, a display tube, or an image pickup tube is fitted with a metal sleeve containing a heater for heating, and one end of the metal sleeve. An indirectly heated cathode structure provided with a cap-shaped metal substrate or the like to which is attached.

FIG. 3 is a cross-sectional view showing an example of the configuration of such a known electron tube cathode.
No. 4130.

In FIG. 3, an electron tube cathode is made of nickel-nickel.
A metal sleeve 31 made of a high melting point metal such as a chromium (Ni-Cr) alloy is fitted to one end of the metal sleeve 31 and contains nickel (Ni) as a main component and silicon (S)
i), a cap-shaped metal substrate 32 containing a trace amount of a reducing metal element such as magnesium (Mg), zirconium (Zr), etc.
And barium (Ba) applied on the surface of the metal base 32.
An electron emitting material layer 33 made of an alkaline earth metal oxide containing helium and a heating heater 3 contained in a metal sleeve 31
4 is provided.

In the electron tube cathode having such a configuration, when heating power is supplied to the heater 34, the heat generated by the heater 34 is transmitted to the metal sleeve 31 and the metal base 32, and then to the electron emitting material layer 33. Then, thermoelectrons are emitted from the electron emitting material layer 33.

[0006]

Recently, in image display electron tubes such as cathode ray tubes, display tubes, and image pickup tubes,
As the definition of the image to be obtained is advanced, those cathodes capable of operating in a high current density state and having stable electron emission characteristics over a long period of time are particularly strongly desired. It has become

In the known electron tube cathode, barium silicate (Ba ₂ SiO ₄ ), barium magnesia (BaMgO ₂ ), or barium zirconate (Ba ₂ SiO ₄ ) is formed at the interface between the metal substrate 32 and the electron emitting material layer 33 during operation. An intermediate material layer (resistive layer) made of BaZrO ₃ ) or the like is formed. These intermediate material layers are accelerated when the electron tube cathode is operated in a high current density state, and the formed intermediate material layer is formed. The layer exhibits a high resistance, which hinders a current flowing at the interface between the metal substrate 32 and the electron emitting material layer 33. At this time, if a high voltage is applied between the cathode and the grid electrode to force high electron emission against the formed intermediate material layer, large Joule heat is generated in the intermediate material layer. As a result, the temperature rises and the formation of an intermediate material layer is promoted, thereby causing a vicious cycle. The intermediate material layer formed at the interface between the metal substrate 32 and the electron emitting material layer 33 is particularly formed in a region facing the electron beam passage hole of the first grid electrode.

As described above, when the known electron tube cathode is operated in a high current density state, the operation in the high current density state is hindered by the formation of the intermediate material layer. There is a problem that stable electron emission characteristics cannot be exhibited for a long time in the state.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to suppress the formation of an intermediate material layer formed at the interface between a metal substrate and an electron emitting material layer, and to provide a long current at a high current density. An object of the present invention is to provide an electron tube cathode capable of exhibiting stable electron emission characteristics over time.

[0010]

In order to achieve the above object, an electron tube cathode according to the present invention comprises a metal substrate and an electron emitting material layer deposited on the metal substrate, and has a surface portion of the metal substrate, that is, a metal substrate. At the interface between the metal substrate and the electron emitting material layer,
Means for forming a donut-shaped thin film region containing a reducing metal element is provided.

According to the above means, during operation, a large amount of barium (Ba) is deposited on the surface of the metal substrate by a reaction occurring between the donut-shaped thin film region containing a high concentration of the reducing metal element and the electron emitting material layer. ) Is generated, and barium silicate (Ba ₂ ) is formed at the interface between the metal substrate and the electron emitting material layer.
An intermediate material layer such as SiO ₄ ) is formed, but when the concentration of barium (Ba) increases, new barium (Ba)
Is suppressed, so that barium silicate (Ba ₂ Si) on the surface of the metal substrate (the interface between the metal substrate and the electron emitting material layer) facing the electron beam passage hole of the first lattice electrode is suppressed.
The formation of an intermediate material layer such as O ₄ ) is also suppressed.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In an embodiment of the present invention, an electron tube cathode is a metal substrate containing nickel (Ni) as a main component and a trace amount of a reducing metal element such as silicon (Si) and magnesium (Mg). And an electron-emitting substance layer made of an alkaline earth metal oxide containing barium (Ba), which is applied on the metal substrate, wherein a donut-like thin film containing a reducing metal element on a surface portion of the metal substrate. An area is formed.

In a preferred example of the embodiment of the present invention, the donut-shaped thin film region has an inner diameter which is equal to or slightly larger than the diameter of the electron beam passage hole of the first lattice electrode, and an outer portion which reaches the outer periphery of the metal base. Having a diameter.

According to these embodiments of the present invention, during operation of the electron tube cathode, the surface portion of the metal base is
A large amount of barium (Ba) is generated by the reaction between the donut-shaped thin film region containing the high-concentration reducing metal element and the electron-emitting material layer, and barium silicate (barium silicate) is formed at the interface between the metal substrate and the electron-emitting material layer. An intermediate material layer such as Ba ₂ SiO ₄ ) is formed. And a large amount of barium (B
When the concentration of barium (Ba) increases due to the generation of a), the generation of new barium (Ba) is suppressed, and at the same time, the surface portion of the metal substrate facing the electron beam passage hole of the first grid electrode. Barium silicate (Ba ₂ Si) at (the interface between the metal substrate and the electron emitting material layer)
The formation of an intermediate material layer such as O ₄ ) is also suppressed.

As described above, according to the embodiment of the present invention, the high resistance state based on the intermediate material layer is alleviated, and the current flowing at the interface between the metal substrate and the electron emitting material layer is greatly increased by the intermediate material layer. Since it is not hindered, it is possible to exhibit stable electron emission characteristics for a long time in a high current density state.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a structural view showing a main part of an embodiment of an electron tube cathode according to the present invention, wherein FIG.
(B) is a configuration diagram of the cap-like metal base side viewed from the line AA ′.

In FIGS. 1 (a) and 1 (b), 1 is a cylindrical metal sleeve made of a nickel-chromium (Ni-Cr) alloy which is a high melting point metal, 2 is nickel (Ni) as a main component and a trace amount. A cap-shaped metal substrate containing silicon (Si) as a reducing metal element, 3 is a donut-shaped thin film region containing a reducing metal element, and 4 is an electron emitting material made of an alkaline earth metal oxide containing barium (Ba). Layer 5 is a heater for heating, 6 is a first grid electrode, and 7 is an electron beam passage hole.

The cylindrical metal sleeve 1 has a cap-shaped metal base 2 fitted at one end, and a heater 5 inserted therein. The doughnut-shaped thin film region 3 is formed on the surface of the cap-shaped metal substrate 2, and the electron-emitting material layer 4 is applied to the surface including the donut-shaped thin film region 3. The first grid electrode 6 is spaced apart from the electron emitting material layer 4, and an electron beam passage hole 7 is provided at a position facing the center of the electron emitting material layer 4. The donut-shaped thin film region 3 is configured such that the inner diameter portion (the portion where the surface of the cap-shaped metal base 2 is exposed) is substantially equal to or slightly larger than the diameter of the electron beam passage hole 7. Is configured to reach a region substantially equal to the outer diameter of the cap-shaped metal base 2. In this case, the cap-shaped metal base 2 and the donut-shaped thin film region 3 constitute a composite metal base 8.

An example of a method for manufacturing the electron tube cathode having the above-described structure, particularly, the cap-shaped metal substrate 2 having the donut-shaped thin film region 3, that is, the composite metal substrate 8, is as follows. Cap-shaped metal base 2 containing nickel (Ni) as a main component and a trace amount of silicon (Si) as a reducing metal element 2
Is manufactured by a known manufacturing process, for example, press working using a press machine or the like. The surface of the obtained cap-shaped metal substrate 2 is masked in a donut shape, and after masking, a binder material composed of nitrocellulose and butyl acetate is applied, and the applied portion is dried. Next, the cap-shaped metal base 2
The surface of the cap-shaped metal substrate 2 is removed by masking the surface of the metal substrate 2 using a sputtering device and sputtering rhenium (Re) on the surface using a sputtering device.
A donut-shaped thin film region 3 of rhenium (Re) is formed.

Next, the cap-shaped metal substrate 2 on which the donut-shaped thin film region 3 is formed is heat-treated in an atmosphere furnace of hydrogen gas (H ₂ ) to scatter the binder material composed of nitrocellulose and butyl acetate, thereby removing the cap-shaped metal substrate 2. And the cap-shaped metal substrate 2 reacts with the donut-shaped thin film region 3 of rhenium (Re). Through such a process, a donut-shaped thin film region 13 containing a high-concentration reducing metal element is formed on the surface of the cap-shaped metal base 2. Subsequently, the cap-shaped metal substrate 2 on which the donut-shaped thin film region 13 is formed
A ternary carbonate {(Ba, Sr, Ca) CO ₃ } containing barium (Ba), strontium (Sr), and calcium (Ca) is spray-coated thereon using a spray gun, and a cap-shaped metal substrate is applied. An electron emitting material layer 4 having a thickness of about 80 μm is formed on the substrate 2. Thereafter, through a known manufacturing process such as a process of fitting the cap-shaped metal base 2 to one end of the metal sleeve 1 and a process of inserting and disposing the heater 5 from the other end of the metal sleeve 1, the electron tube cathode is formed. Manufactured.

The electron tube cathode configured as described above operates as follows. When heating power is supplied to the heating heater 5, heat generated by the heating of the heating heater 5 is transmitted to the metal sleeve 1 and the cap-shaped metal base 2, then to the electron emitting material layer 4, and from the electron emitting material layer 4. Thermal electrons are emitted.

When such a thermionic emission operation is performed, on the surface of the cap-shaped metal substrate 2, the donut-shaped thin film region 3 containing a high-concentration reducing metal element and the electron-emitting material layer 4 are interposed. A large amount of barium (B
a) is generated, and an intermediate material layer such as barium silicate (Ba ₂ SiO ₄ ) is formed at the interface between the cap-shaped metal substrate 2 and the electron emitting material layer 4. When the barium (Ba) concentration is increased to some extent due to the generation of a large amount of barium (Ba), the generation of new barium (Ba) is suppressed, so that barium silicate (Ba ₂ SiO _{2) is used.
4} ) The formation of an intermediate material layer is suppressed, and barium silicate () is formed at the interface between the cap-shaped metal substrate 2 and the electron emitting material layer 4 facing the electron beam passage hole 7 of the first grid electrode 6 having a large current density. The formation of an intermediate material layer such as Ba ₂ SiO ₄ ) can also be suppressed.

As described above, in the electron tube cathode according to the present embodiment, even if the current density flowing through the cathode is increased, the formation of an intermediate material layer such as barium silicate (Ba ₂ SiO ₄ ) is suppressed. The generation of Joule heat due to the intermediate layer of the resistance is reduced, and stable electron emission characteristics can be exhibited over a long period of time even when operated in a high current density state.

Here, FIG. 2 is a characteristic diagram comparing the electron emission characteristics of the electron tube cathode according to the present embodiment with a known electron tube cathode.

In FIG. 2, the vertical axis represents the electron activity expressed as a relative value to the value (100) when the operation elapsed time is 0, and the horizontal axis represents the operation elapsed time expressed in kilohours (Kh). A shows the characteristics of the electron tube cathode according to the present embodiment, and curve B shows the characteristics of the known electron tube cathode.

As shown by the curve B in FIG. 2, in the known electron tube cathode, the emissivity gradually decreases as the operation elapsed time becomes longer, and the relative value of the emissivity becomes 65% in 10,000 hours. , 15000 hours, the relative value of the electron activity decreases to about 50%, whereas the electron tube cathode according to the present embodiment has the same decrease in the electron activity as the operation elapsed time becomes longer. Even so, the rate of reduction is considerably smaller than that of the known electron tube cathode.
In 0000 hours, the relative value of the electron activity becomes 85%, 150
At 00 hours the relative value of the electron activity only drops to about 80%. Thus, the electron tube cathode according to the present embodiment is
It can be seen that it has much better life characteristics than known electron tube cathodes.

In this embodiment, the donut-shaped thin film region 3
The inner diameter of the doughnut-shaped thin film region 3 may be approximately equal to the diameter of the electron beam passage hole of the first lattice electrode 6, and may be slightly larger than the diameter of the electron beam passage hole of the first lattice electrode 6.
The effect of providing is remarkable. The outer diameter of the donut-shaped thin film region 3 may be selected so as to reach the outer periphery of the cap-shaped metal base 2.

In this case, as the reducing metal element contained in the donut-shaped thin film region 3, in addition to rhenium (Re),
Among elements such as hafnium (Hf), zirconium (Zr), silicon (Si), aluminum (Al), tungsten (W), molybdenum (Mo), tantalum (Ta), niobium (Nb), and magnesium (Mg) One or more are used.

The doughnut-shaped thin film region 3 may be formed by ion implantation instead of the above-described sputtering using a sputtering apparatus.

The donut-shaped thin film region 3 may be in the form of a thin film layer containing a large amount of reducing metal elements, or may be in the form of an alloy layer integrated with the cap-shaped metal base 2. However,
In the case of forming a thin film layer, heat treatment is performed before depositing the electron emitting material layer 4 made of an alkaline earth metal oxide containing barium (Ba) to form an alloy with the cap-shaped metal base 2. It is desirable to achieve

After operating the electron tube cathode of this embodiment and the known electron tube cathode for 10,000 hours, respectively, the electron emitting materials 4 and 33 were removed from the surface of the cap-shaped metal base 2 and a minute X-ray having a beam diameter of about 100 μm was obtained. An intermediate product formed at the center of the surface of the cap-shaped metal bases 2 and 32 using the analyzer;
That is, when the amount of barium silicate (Ba ₂ SiO ₄ ) was compared, the amount of the electron tube cathode formed in this embodiment was about の that of the known electron tube cathode, and the amount was small. On the other hand, in the electron tube cathode according to the present embodiment, a large amount of intermediate products are formed around the cap-shaped metal substrate 2, which confirms that a large amount of barium (Ba) related to electron emission was generated. . This is the reason why the electron tube cathode of this embodiment can maintain good electron emission characteristics.

In the above embodiment, an example was described in which the reducing metal element in the cap-shaped metal substrate 2 was silicon (Si), but the reducing metal element in the cap-shaped metal substrate 2 in the present invention was described. The element is not limited to silicon (Si), and other reducing metal elements, for example, magnesium (M
The same effect can be obtained by using g), zirconium (Zr), tungsten (W), or a composite thereof.

[0034]

As described above, according to the present invention, during operation of the electron tube cathode, the surface portion of the metal substrate facing the electron beam passage hole of the first grid electrode (the interface between the metal substrate and the electron emitting material layer). Part), the formation of the intermediate material layer is suppressed,
Since the high-resistance state based on the intermediate material layer is relaxed, the current flowing at the interface between the metal substrate and the electron-emitting material layer is not significantly obstructed by the intermediate material layer, and the device operates continuously at a high current density state. Even so, there is an effect that stable electron emission characteristics can be maintained for a long time.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a main part of one embodiment of an electron tube cathode according to the present invention.

FIG. 2 is a characteristic diagram comparing the electron emission characteristics of the electron tube cathode according to the present embodiment and a known electron tube cathode.

FIG. 3 is a cross-sectional view showing an example of a configuration of a known electron tube cathode.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Metal sleeve 2 Cap-shaped metal base 3 Donut-shaped thin film area 4 Electron emitting material layer 5 Heater 6 First lattice electrode 7 Electron beam passage hole

Claims (2)

[Claims] 1. A metal substrate containing nickel as a main component and a trace amount of a reducing metal element such as silicon and magnesium, and an electron deposited on the metal substrate and made of an alkaline earth metal oxide containing barium. An electron tube cathode comprising a radiating material layer, wherein a donut-shaped thin film region containing a reducing metal element is formed on a surface portion of the metal substrate. 2. The donut-shaped thin film region has an inner diameter that is equal to or slightly larger than the diameter of the electron beam passage hole of the first lattice electrode, and an outer diameter that reaches the outer periphery of the metal base. 2. The electron tube cathode according to claim 1, wherein: