JPH11213858A - Cathode structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To properly conduct heat transfer from a heater wide to a cathode sleeve for the prevention of the breakage of a coat layer by winding the heater wire having the surface covered with an insulating material on the circumferential surface of the cathode sleeve consisting of a conductive material and having a cathode base, and covering the heater wire with a coat layer. SOLUTION: A circular cathode base 11, consisting of a porous V base with a porosity of about 20% impregnated with an electron-emitting material is fitted and brazed to one end opening part of a cylindrical cathode sleeve 12 formed of Mo and having openings in both ends. The surface of a heater wire 13 formed of a conductive metal (for example, copper) is covered with an insulating coating layer 14 of about 100 μm thickness formed by electrode position by the use of, for example, alumina, and the heater wire 13 is wound directly on the circumference of the cathode sleeve 12. A cost layer 15 of about 0.35 mm thickness is formed adhering closely on the circumferential surface of the cathode sleeve 12 having the heater wire 13 wound thereon by plasma flame coating, and fixed so as not to be peeled off by an external force. As a result of this, a cathode structure in which the heater wire 13 is surely fixed can be provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a cathode structure.

[0002]

2. Description of the Related Art Conventionally, a cathode structure used for an electron tube is disclosed in Japanese Utility Model Laid-Open No. 1-165549.
FIG. 3 is a sectional view showing the structure of the cathode assembly. In FIG. 3, reference numeral 1 denotes a cathode base, which has an electron-emitting substance. Reference numeral 2 denotes a cylindrical cathode sleeve, which is formed of a conductive metal. The cathode base 1 is fitted and fixed to one end of the cathode sleeve 2. Reference numeral 3 denotes a primary insulating coating layer, which is formed in a cylindrical shape on the outer peripheral surface of the cathode sleeve 2. The primary insulating coat layer 3 is formed by plasma spraying alumina powder.

[0003] Reference numeral 4 denotes a heater wire, which is made of a conductive metal wire. The heater wire 4 is provided on the outer peripheral surface of the primary insulating coat layer 3 by being wound around the cathode sleeve 2 in a coil shape along the axial direction, and is connected to a power source (not shown). Reference numeral 5 denotes a secondary insulating coat layer made of alumina, which is formed in a cylindrical shape on the outer peripheral surface of the primary insulating coat layer 3 so as to cover the heater wire 4. The secondary insulating coating layer 5 is formed by flame spraying an alumina powder.

Since the heater wire 4 is bare and wound around the cathode sleeve 2, it is necessary to provide electrical insulation for the cathode sleeve 2 and electrical insulation between the heater wires 4.

Therefore, the primary insulating coat layer 3 is provided between the cathode sleeve 2 and the heater wire 4 to maintain electrical insulation of the heater wire 4 from the cathode sleeve 2. The secondary insulating coat layer 5 is located outside the primary insulating coat layer 3 and maintains electrical insulation between the heater wires 4 and the outside of the heater wires 4.

In the cathode assembly having such a configuration, when a current is supplied from a power supply to the heater wire 4, the heater wire 4 generates heat due to resistance heating. This heat is conducted from the primary insulating coat layer 3 through the cathode sleeve 2 to heat the cathode base 1.
The cathode substrate 1 is heated to emit electrons.

In this cathode assembly, the primary insulating coating layer 3 is formed by plasma spraying, and the secondary insulating coating layer 5 is formed by flame spraying. In the plasma spraying and the flame spraying, alumina powder is fed into a heat source, melted and sprayed to form coat layers 3 and 5 on the outer peripheral surface of the cathode sleeve 2 and the outer peripheral surface of the primary insulating coat layer 3. When the coating layer is formed by this thermal spraying, the cathode sleeve 2 is rotated around its axis to receive the alumina powder, thereby forming the coating layers 3 and 5 on the entire outer circumferential surface of the cathode sleeve 2 in the circumferential direction. I am trying to do it.

However, when the coating layers 3 and 5 are formed while rotating the cathode sleeve 2 about its axis as described above, the cathode sleeve 2 rotates eccentrically, and the injection of alumina to the cathode sleeve 2 becomes uneven. The coating layers 3 and 5 formed on the cathode sleeve 2
May vary in thickness. Further, when performing thermal spraying, the alumina powder is a material having a high melting point, so that it is not completely dissolved. 3, 5 are formed. As described above, irregularities occur on the outer peripheral surfaces of the coat layers 3 and 5 in which the alumina particles in the semi-dissolved state are accumulated.

In this case, irregularities may occur on the outer peripheral surface of the primary insulating coat layer 3. Therefore, when the heater wire 4 is wound in a coil shape around the outer peripheral surface of the primary insulating coat layer 3, a gap is formed between the heater wire 4 and the concave portion of the primary insulating coat layer 3 so that the heater wire 4 is There is a portion that does not adhere sufficiently to the outer peripheral surface of the layer 3.

Further, when the secondary insulating coating layer 5 is formed on the outer peripheral surface of the primary insulating coating layer 3, the presence of a gap between the heater wire 4 and the primary insulating coating layer 3 causes the secondary insulating coating layer 5 to be in contact with the primary insulating coating layer 3. The contact area with the insulating coat layer 3 decreases, and the bonding strength of the secondary insulating coat layer 5 to the primary insulating coat layer 3 decreases. For this reason, when vibration generated in the heater wire 4 when the heater wire 4 is energized is applied to the secondary insulating coat layer 5, the secondary insulating coat layer 5 is cracked or the secondary insulating coat layer 5 is Peel from

[0011]

As described above, the conventional cathode assembly is provided with the primary insulating coat layer 3 for electrically insulating the cathode sleeve 2 and the heater wire 4 from each other.
Is provided with a secondary insulating coat layer 5 for insulation fixing.

For this reason, in the manufacturing process of the cathode structure, the thermal spraying for forming the insulating coat layer must be performed twice, and the manufacturing cost is high. Further, the adhesion between the primary insulation coat layer 3 and the heater wire 4 is poor, and the degree of heat transfer from the heater wire 4 to the cathode substrate 1 via the primary insulation coat layer 3 may be reduced. Further, the bonding strength of the secondary insulating coat layer 5 to the primary insulating coat layer 3 is reduced, and cracks and peeling occur in the secondary insulating coat layer 5, whereby the insulating effect of the secondary insulating coat layer 5 on the heater wire 4 is reduced. Heater wire 4
May be short-circuited at each of the coil portions. If the cathode structure is used for a traveling wave tube mounted on an artificial satellite, there is a problem in vibration resistance.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a cathode structure which has good heat conduction from a heater wire to a cathode sleeve, prevents breakage of a coat layer, and is easy to manufacture. And

[0014]

According to a first aspect of the present invention, there is provided a cathode assembly comprising: a cathode base; a cathode sleeve formed of a conductive material provided with the cathode base; A heater wire covered with an insulating material;
A coating layer formed on the outer peripheral surface of the cathode sleeve so as to cover the heater wire.

According to the structure of the present invention, the heater wire can be wound directly on the outer peripheral surface of the cathode sleeve, so that the heater wire is easily manufactured. Heat can be efficiently transmitted to the cathode base via the cathode sleeve. The coat layer can be formed in close contact with the outer peripheral surface of the cathode sleeve and the insulating coating layer of the heater wire, and can be securely fixed without being peeled off by an external force.

According to a second aspect of the present invention, in the cathode structure according to the first aspect, an insulating material forming a layer covering the surface of the heater wire and an insulating material forming a coat layer on an outer peripheral surface of the cathode sleeve are provided. It is the same.

According to the structure of the present invention, the heater wire can be reliably fixed by integrally forming the insulating coating layer of the heater wire and the coat layer of the cathode sleeve. Further, the electrical insulation of the heater wire can be further improved.

According to a third aspect of the present invention, in the cathode structure according to the first aspect, the material forming the coat layer on the outer peripheral surface of the cathode sleeve is a conductive material. According to the configuration of the present invention, the coat layer can be formed of a conductive material.

A cathode structure according to a fourth aspect of the present invention comprises a cathode base, a cathode sleeve formed of an insulating material and provided with the cathode base, a heater wire wound around the outer peripheral surface of the cathode sleeve, A coating layer formed on an outer peripheral surface of the sleeve and made of an insulating material for covering the heater wire and fixing the heater wire.

According to the structure of the present invention, the heater wire can be wound directly on the outer peripheral surface of the cathode sleeve, so that the heater wire can be easily manufactured. Heat can be efficiently transmitted to the cathode base via the cathode sleeve. The coat layer can be formed in close contact with the outer peripheral surface of the cathode sleeve and the insulating coating layer of the heater wire, and can be securely fixed without being peeled off by an external force.

According to the fifth aspect of the present invention, in the cathode structure according to the fourth aspect, the insulating material forming the cathode sleeve is the same as the insulating material forming the coat layer on the outer peripheral surface of the cathode sleeve. It is characterized by. According to the present invention, the heater wire can be securely fixed by integrally forming the insulating layer of the heater wire and the coat layer of the cathode sleeve.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIG. FIG. 1 shows a cathode structure according to this embodiment. In FIG. 1, reference numeral 11 denotes a cathode substrate. The cathode substrate 11 is of an impregnated type in which a porous tungsten substrate having a porosity of 20% is impregnated with an electron emitting substance. The cathode base 11 has, for example, a circular shape. Reference numeral 12 denotes a cathode sleeve, and the cathode sleeve 12 is formed of molybdenum. The cathode sleeve 12 has a cylindrical body whose both ends are open. The cathode base 11 is fitted to one end opening of the cathode sleeve 12 with the electron emission surface on the outside, and is brazed using a ruthenium-molybdenum brazing material.

Reference numeral 13 denotes a heater wire. The heater wire 13 is formed of a conductive metal, for example, copper. The surface of the heater wire 13 is covered with an insulating coating layer 14. The insulating coating layer 14 is formed by electrodeposition using an insulating material, for example, alumina. The thickness of the insulating coating layer 14 is, for example, 100 μm. The heater wire 13 is directly wound around the outer peripheral surface of the cathode sleeve 12, and is connected to a power source (not shown).

Reference numeral 15 denotes a coating layer. The coating layer 15 covers the outer peripheral surface of the cathode sleeve 12 and the heater wire 13 wound around the outer peripheral surface of the cathode sleeve 12. It is fixed on top. The coat layer 15 is formed by plasma spraying using, for example, an insulating material, specifically, alumina which is the same material as the material forming the insulating coating layer 14 of the heater wire 13. The coat layer 15 has a thickness of, for example, 0.35 mm.

According to this configuration, the insulating coating layer 14 formed on the surface of the heater wire 13 provides electrical insulation between the cathode sleeve 12 and the heater wire 13 wound around the cathode sleeve 12, and various parts of the heater wire 13. The mutual electrical insulation and the electrical insulation to the outside of the heater wire 13 are ensured, respectively. A coat layer 15 formed on the outer peripheral surface of the cathode sleeve 12 fixes the heater wire 13 wound around the cathode sleeve 12.

For this reason, in this cathode assembly, the heater wire 13 is not wound around the outer peripheral portion of the insulating coat layer formed directly on the outer peripheral surface of the cathode sleeve 12 as in the prior art, but is provided on the outer peripheral surface of the cathode sleeve 12. Since the heater wire 13 can be wound directly, manufacturing is easy. Further, in this cathode assembly, the heater wire 13 is closely attached to the outer peripheral surface of the cathode sleeve 12 so that the heat of the heater wire 13 can be efficiently transmitted to the cathode base 11 via the cathode sleeve 12. Further, in this cathode assembly, the coating layer 15 is
2 can be formed in close contact with the outer peripheral surface of the heater wire 13 and the insulating coating layer 14 of the heater wire 13. Therefore, the coat layer 15 does not peel off due to external force, and the heater wire 13 is connected to the cathode sleeve 12.
Can be securely fixed.

In this embodiment, the material for forming the coating layer 15 is the same insulating material (alumina) as the insulating material (alumina) for forming the insulating coating layer 14 that covers the surface of the heater wire 13. In this case, the coat layer 15
The heater wire 13 is securely fixed on the outer peripheral surface of the cathode sleeve 12 integrally with the insulating coating layer 14 of the heater wire 13, and the electrical insulation of the heater wire 13 is further enhanced.

The cathode assembly according to this embodiment has a vacuum degree of 10 ^-7.
When a test was conducted for 10 hours by supplying electricity so that the heater temperature became 1300 ° C. inside the vacuum chamber of Torr, the temperature of the cathode substrate 11 was stable without change, and the coating layer 15 did not peel off.

The material for forming the coat layer 15 on the outer peripheral surface of the cathode sleeve 12 can be formed of a conductive material. In particular, when the material for forming the coat layer 15 is formed of the same conductive material as the material for forming the cathode sleeve 12, for example, molybdenum, the fixing strength of the coat layer 15 is further increased, and the peeling from the cathode sleeve 12 can be completely suppressed. it can.

If the cathode assembly of this embodiment is used for an electron gun assembly, a highly reliable electron gun assembly can be obtained. When this electron gun assembly is used for an electron tube, a highly reliable electron tube can be obtained.

A second embodiment will be described with reference to FIG. FIG. 2 shows a cathode structure according to this embodiment. In FIG. 2, reference numeral 21 denotes a cathode base.
Is an oxide form in which an oxide is formed on the surface of a base metal, for example. The cathode base 21 has, for example, a circular shape. 22 is a cathode sleeve, this cathode sleeve 22 is an insulating material,
For example, it is formed of 99.5% alumina. The cathode sleeve 22 has a cylindrical body whose both ends are open.
The cathode substrate 21 has the electron emission surface on the outside and the cathode sleeve 2
2 is fitted and fixed to a cap 23 made of tantalum fitted and fixed to one end opening.

Reference numeral 24 denotes a heater wire, and the heater wire 24 is formed of a conductive metal, for example, copper. Heater wire 24
Is wound directly around the outer peripheral surface of the cathode sleeve 22 and is connected to a power source (not shown).

A coating layer 25 covers the outer peripheral surface of the cathode sleeve 22 and the heater wire 24 wound around the outer peripheral surface of the cathode sleeve 22. It is fixed on top. The coating layer 25 is formed by plasma spraying using an insulating material, for example, the same insulating material as the insulating material forming the cathode sleeve 22, specifically, alumina. The thickness of the coat layer 25 is, for example, 0.3 mm.

According to this configuration, the cathode sleeve 22 made of an insulating material ensures electrical insulation between the cathode sleeve 22 and the heater wire 24 wound therearound. The coat layer 25 made of an insulating material secures electrical insulation between the respective portions of the heater wire 24 wound around the cathode sleeve 22 and electrical insulation to the outside of the heater wire 24, and also connects the heater wire 24 to the cathode sleeve 22. Fix it.

For this reason, in this cathode assembly, the heater wire 24 can be wound directly on the outer peripheral surface of the cathode sleeve 22 without directly forming the coat layer 25 on the outer peripheral surface of the cathode sleeve 22, which facilitates manufacture. It is. Further, in this cathode structure, the heater wire 24 is directly adhered to the outer peripheral surface of the cathode sleeve 22 so that the heat of the heater wire 24 can be efficiently transmitted to the cathode base 21 via the cathode sleeve 22. Further, in this cathode assembly, the coating layer 25 is
2 can be formed in close contact with the outer peripheral surface of the heater wire 24, so that the coat layer 25 does not peel off even when an external force is applied, and the heater wire 24 can be securely fixed.

If the insulating material forming the cathode sleeve 24 and the insulating material forming the coat layer 25 on the outer peripheral surface of the cathode sleeve 24 are the same, the cathode sleeve 24 and the coat layer 25
And the heater wire 24 can be securely fixed.

The cathode assembly of this embodiment is set to a degree of vacuum of 10 ^-7.
Electricity was supplied to the heater inside the vacuum chamber at 1300 ° C. to conduct the test for 10 hours. As a result, the temperature of the cathode substrate 21 did not change and was stable, and the coating layer 25 did not peel off.

If the cathode assembly of this embodiment is used for an electron gun assembly, a highly reliable electron gun assembly can be obtained. When this electron gun assembly is used for an electron tube, a highly reliable electron tube can be obtained. The present invention is not limited to the above-described embodiment, but can be implemented with various modifications.

[0039]

According to the cathode structure of the first aspect of the present invention, the heater wire can be wound directly on the outer peripheral surface of the cathode sleeve, thereby facilitating the manufacture. And the heat of the heater wire can be efficiently transmitted to the cathode base via the cathode sleeve. Further, the coat layer can be formed in close contact with the outer peripheral surface of the cathode sleeve and the insulating coating layer of the heater wire, and can be securely fixed without being peeled off by an external force.

According to the second aspect of the present invention, the insulating coating layer of the heater wire and the coat layer of the cathode sleeve are integrally formed, so that the heater wire can be securely fixed by the coat layer and the electrical insulation of the heater wire can be improved. Can be even higher.

According to the third aspect of the present invention, the coat layer can be formed of a conductive material. According to the cathode structure of the fourth aspect of the present invention, the heater wire can be wound directly on the outer peripheral surface of the cathode sleeve, and the manufacture is easy.
The heater wire is closely attached to the outer peripheral surface of the cathode sleeve, so that the heat of the heater wire can be efficiently transmitted to the cathode base via the cathode sleeve. Further, the coat layer can be formed in close contact with the outer peripheral surface of the cathode sleeve and the insulating coating layer of the heater wire, and the heater wire can be securely fixed without peeling off the coat layer by an external force. According to the fifth aspect of the present invention, the coat layer of the cathode sleeve and the insulating coating layer of the heater wire can be integrally fixed to the heater wire.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a cathode structure according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a cathode structure according to a second embodiment.

FIG. 3 is a cross-sectional view illustrating a conventional cathode assembly.

[Explanation of symbols]

 11: cathode base, 12: cathode sleeve, 13: heater, 14: insulating coating layer, 15: coat layer, 21: cathode base, 22: cathode sleeve, 24: heater, 25: coat layer.

Claims (5)

[Claims] 1. A cathode base, a cathode sleeve made of a conductive material provided with the cathode base, a heater wire wound around an outer peripheral surface of the cathode sleeve and covered with an insulating material, And a coat layer formed on the outer peripheral surface to cover the heater wire. 2. The material for forming a coat layer on the outer peripheral surface of the cathode sleeve is the same as the insulating material for forming a layer covering the surface of the heater wire. Cathode structure. 3. The cathode structure according to claim 1, wherein the material forming the coat layer on the outer peripheral surface of the cathode sleeve is a conductive material. 4. A cathode base, a cathode sleeve formed of an insulating material and provided with the cathode base, a heater wire wound on an outer peripheral surface of the cathode sleeve, and a heater wire on an outer peripheral surface of the cathode sleeve. And a coat layer made of an insulating material formed so as to cover the cathode structure. 5. The cathode structure according to claim 4, wherein the insulating material forming the cathode sleeve is the same as the insulating material forming the coat layer on the outer peripheral surface of the cathode sleeve.