JP2003068220A - Magnetron - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetron in which positional deviation of cathodes is hardly caused even if its external terminals for supplying a voltage to a filament are under considerable force. SOLUTION: This magnetron comprises a cathode 15 of which the opening end portion of a cylinder-like metal envelope 24 is hermetic-sealed to a stem insulating body 20, and a filament 19 is disposed at a central axis portion of an anode 8, and a pair of cathode leads 16 for supporting the cathode 15, and sealing metal plates 23 which are hermetic-jointed to the face on the vacuum vessel side of the stem insulating body 20. And each cathode lead 16 is connected with an external terminal 22 by being inserted into a through hole 21 of the stem insulating body 20, and a protruded portions 22a which abuts against the inside face of the through hole 21 is formed on the outside surface of the external terminal 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetron mounted on a microwave oven or the like for generating microwaves.

[0002]

2. Description of the Related Art FIG. 6 is a sectional view of a cathode portion of a conventional magnetron for a microwave oven, and FIG. 7 is a sectional view of a main portion in FIG.

In the figure, reference numeral 100 denotes a cathode composed of a filament 104 sandwiched between a pair of cathode leads 101 via a top hat 102 and an end hat 103. The filament 104 is fed by an external terminal 105. Emits thermoelectrons.

The cathode lead 101 is fixed to a sealing metal plate 107 that is airtightly joined to a stem insulator 106 made of ceramic, and the external terminal 105 inserted through a through hole 106a of the stem insulator 106 is a cathode lead. It is joined to 101.

However, in the above-described structure, the gap S is formed between the external terminal 105 and the through hole 106a of the stem insulator 106 in consideration of the dimensional intersection of the parts. Therefore, during the assembly process, when a force is applied to the external terminal 105, the cathode lead 101 moves around the portion where the cathode lead 101 and the sealing metal plate 107 are fixed between the gaps S as a fulcrum. 100 is displaced from the predetermined position, and the filament 10
4 has a problem such as disconnection and deterioration of operating characteristics.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetron in which the position of the cathode is unlikely to shift even if a force is applied to the external terminal for supplying power to the filament.

[0007]

SUMMARY OF THE INVENTION The present invention comprises a cylindrical metal container which is hermetically bonded to an anode and constitutes a part of a vacuum container,
A stem insulator in which the open end of the cylindrical metal container is airtightly bonded to the periphery thereof, a cathode in which a filament is arranged on the central axis of the anode, a pair of cathode leads supporting the cathode, and the cathode. A magnetron including a sealing metal plate that is in close contact with the outer circumference of the lead and is airtightly bonded to the surface of the stem insulator on the vacuum container side, and an external terminal that is inserted through a through hole of the stem insulator and is connected to the cathode lead. In addition, a protrusion that abuts the inner surface of the through hole is formed on the outer periphery of the external terminal.

With the above structure, when a negative voltage, for example, a high voltage of 4 kV is applied to the cathode and a magnetic field is further applied to the cathode shaft, electrons emitted from the filament are swirled by the power supplied from the external terminal. The swirling electrons oscillate in synchronization with the high frequency electric field of the anode, and microwaves are emitted.

Further, since a protrusion that abuts the inner surface of the through hole is formed on the outer periphery of the external terminal, an assembly process until the magnetron is completed, for example, power is supplied to the cathode to feed the filament. Even if a force is applied to the external terminal in the step of forming a carbonized layer on the surface, the inspection step of confirming the operation, etc., the protrusion prevents the cathode lead from moving in the gap between the external terminal and the through hole. It Therefore, since no force is applied to the portion where the cathode lead and the sealing metal plate are fixed, the cathode is not displaced from the predetermined position, the filament is broken, and the operating characteristics are deteriorated. Can be prevented.

Further, since the protrusion is located in the vicinity of the opening of the through hole facing the vacuum container when the external terminal and the cathode lead are connected, the protrusion is , The cathode lead is formed at the farthest position on the through hole from the portion of the sealing metal plate to which the cathode lead is fixed, and the protrusion allows the cathode lead to move even if a force is applied to the external terminal. It is possible to prevent the filament from being broken and the operating characteristics from being deteriorated because the cathode is not displaced from a predetermined position due to the restriction.

Further, a tubular metal container which is airtightly joined to the anode and constitutes a part of the vacuum container, a stem insulator whose open end is airtightly joined to the periphery of the tubular metal container, and a center of the anode A cathode in which a filament is arranged on the shaft, and a pair of cathode leads supporting the cathode,
A sealing metal plate that is in close contact with the outer periphery of the cathode lead and is airtightly bonded to the surface of the stem insulator on the vacuum container side, and an external terminal that is inserted from a through hole of the stem insulator and is connected to the cathode lead The magnetron is characterized in that a protrusion is formed on the inner surface of the through hole so as to contact the outer periphery of the external terminal.

With the above structure, the inner surface of the through hole is formed with the convex portion that comes into contact with the outer periphery of the external terminal. Therefore, the assembly process until the magnetron is completed, for example,
Even if a force is applied to the external terminal in the step of forming a carbonized layer on the surface of the filament by supplying power to the cathode, the inspection step for confirming the operation, etc., the gap between the external terminal and the through hole is caused by the convex portion. Thus, the movement of the cathode lead is restricted. Therefore, since no force is applied to the portion where the cathode lead and the sealing metal plate are fixed, the cathode is not displaced from the predetermined position, the filament is broken, and the operating characteristics are deteriorated. It can be prevented.

Further, since the convex portion is located in the vicinity of the opening of the through hole facing the vacuum container when the external terminal and the cathode lead are connected, the convex portion is , The cathode lead is formed at the farthest position on the through hole from the portion of the sealing metal plate to which the cathode lead is fixed, and the convex portion ensures the movement of the cathode lead even when a force is applied to the external terminal. It is possible to prevent the filament from being broken and the operating characteristics from being deteriorated because the cathode is not displaced from a predetermined position.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a longitudinal sectional view of a magnetron showing a first embodiment of the present invention, FIG. 2 is a longitudinal sectional view of a main part in FIG. 1, and FIG. 3 is a sectional view taken along line AA '.

Reference numeral 1 is a magnetron body which is a bipolar vacuum tube covered with a yoke 2 and a radiation fin 3.

Reference numeral 4 is a capacitor 5 for suppressing noise.
And the case where the choke coil 6 is built in.
A lid 7 is attached in close contact with the opening so that noise does not leak outside.

Reference numeral 8 denotes a magnetron anode, which is made of oxygen-free copper and constitutes an anode cylinder 9 which constitutes a part of the vacuum wall of the main body 1, and which is radially formed on the inner circumference of the anode cylinder 9. An even number of vanes 10 are provided, and every other one of the vanes 10 is connected by a small diameter (inner) inner strap ring 11 and a large diameter (outer) outer strap ring 12 to oscillate in a stable π mode. Is configured.

Reference numeral 13 is a ring-shaped permanent magnet disposed above and below the anode 8. The magnetic field of the permanent magnet 13 is provided with the cathode 15 which will be described later and is provided at the tip of the vane 10 and the center of the anode cylinder 9. Each of the pole pieces 14 is provided for concentrating in the working space between them.

A cathode 15 is composed of a filament 19 sandwiched between both ends of a pair of cathode leads 16 via a top hat 17 and an end hat 18, and the filament 19 heats the filament 19 by supplying power from the cathode lead 16. Electrons are emitted. Since the temperature of the filament 19 at this time is as high as about 1800 ° C., the top hat 17, the end hat 18,
The cathode lead 16 is made of molybdenum having a high melting point and a high hardness.

Reference numeral 20 denotes a high heat resistant stem insulator made of alumina ceramic or the like, and the cathode lead 16 and an external terminal 22 described later are inserted through a pair of through holes 21.

Reference numeral 22 denotes an external terminal formed in a cylindrical body by a metal steel plate whose surface is plated with nickel. The outer terminal 22 has a protrusion 22a formed on the outer periphery thereof so as to contact the inner surface of the through hole 21. Has been done. The one end opening 22b of the external terminal 22 is connected to the cathode lead 16
And then joined by brazing, and the other end opening 22
The choke coil 6 is provided on the bent portion 22d formed from
Are joined together by welding. The protrusion 22a is located in the vicinity of an opening of the through hole 21 that faces a later-described cylindrical metal container 24 when the one end opening 22b and the cathode lead 16 are connected. With this configuration, for example, even when a force is applied to the external terminal 22 in a step of forming a carbonized layer on the surface of the filament 19 by supplying power to the cathode 16 or an inspection step for confirming the operation, the protruding portion 22a is Since the cathode lead 16 is in contact with the inner surface of the through hole 21, the movement of the cathode lead 16 is restricted by the gap S between the external terminal 22 and the through hole 21, and the cathode 15 is not displaced from a predetermined position. .

Reference numeral 23 is a sealing metal plate on which a flat surface portion 23a and a cylindrical portion 23b are formed. The flat surface portion 23a is hermetically joined to a joint portion formed on the peripheral edge of the through hole 21 by brazing. The cylindrical portion 23b is airtightly joined to the outer circumference of the cathode lead 16 by brazing, and reliably seals the outside air from the outside terminal 22 side.
In addition, since the flat surface portion 23a is formed in an elliptical shape, it is possible to place the sealing metal plate 23 on the stem insulator 20 regardless of the left-right directionality during the assembly work. 24, which improves workability, is a cylindrical metal container that is airtightly joined to the anode 8 and forms a part of a vacuum container, and the open end of the cylindrical metal container 24 has a cylindrical metal of the stem insulator 20. It is airtightly joined to the joint portion of the cylindrical metal container 24 formed on the outer peripheral edge of the container 24 side by brazing.

Reference numeral 25 is a concave groove formed in an annular shape between the joint portion of the stem insulator 20 with the cathode lead 16 and the joint portion of the cylindrical metal container 24, and the concave groove 25 is the cathode. It is formed to increase the surface area of the stem insulator 20 so that thermoelectrons output from the leads 16 are not discharged to the cylindrical metal container 24 side. Further, the joint portion of the cathode lead 16 and the joint portion of the cylindrical metal container 24 are formed on the same plane of the stem insulator 20, and the surface of each joint portion is molybdenum (Mo). ) And manganese (Mn) are applied, and after a dry firing process is performed, nickel (Ni) plating for improving brazing is applied to form a metallized layer.

With the above structure, when a negative voltage, for example, a high voltage of 4 kV is applied to the cathode 15 and further power is supplied from the external terminal 22 so that a current of about 10 A flows to the filament 19, the permanent magnet The magnetic field from 13 swirls the electrons emitted from the filament 19, and the swirling electrons oscillate in synchronization with the high-frequency electric field of the anode 8 to emit microwaves.

Then, the external terminal 22 is subjected to a force in an assembly process until the magnetron is completed, for example, a process of supplying power to the cathode 15 to form a carbonized layer on the surface of the filament 19 and an inspection process for confirming the operation. Even if is added, since the protrusion 22a is in contact with the inner surface of the through hole 21, the movement of the cathode lead 16 is restricted by the gap S between the external terminal 22 and the through hole 21. Therefore, no force is applied to the portion of the sealing metal plate 23 to which the cathode lead 16 is fixed, so that the cathode 1
It is possible to prevent the filament 19 from breaking and the operating characteristics from deteriorating without the 5 being displaced from the predetermined position.

The protrusion 22a is farthest from the portion of the sealing metal plate 23 on the through hole 21 when the one end opening 22b of the external terminal 22 and the cathode lead 16 are connected. Since it is formed at the position, even if a force is applied to the external terminal 22, the movement of the cathode lead 16 can be reliably regulated by the protrusion 22a.

Next, the second embodiment of the present invention will be described with reference to FIG.
And it demonstrates based on FIG. FIG. 4 is a longitudinal sectional view of a main part of a magnetron showing a second embodiment of the present invention, and FIG. 5 is a longitudinal sectional view of the stem insulator. The same components as those in the first embodiment are designated by the same reference numerals, and only different portions will be described.

Reference numeral 26 denotes an external terminal formed in a cylindrical body by a metal steel plate whose surface is plated with nickel. One end opening 26a of the external terminal 26 is inserted into the cathode lead 16 and joined by brazing. The end of the choke coil 6 is joined by welding to the bent portion 26c formed from the other end opening 26b.

Reference numeral 27 denotes a high heat resistant stem insulator made of alumina ceramic or the like, and a pair of through holes 28 through which the cathode lead 16 and the external terminal 26 are inserted are formed, and the inner surface of the through hole 28 is formed. A convex portion 27a is formed on the outer periphery of the external terminal 26. The convex portion 27a is located near the opening of the through hole 28 facing the cylindrical metal container 24 when the one end opening 26a and the cathode lead 16 are connected.

With the above-described structure, the external terminal is used in an assembly process until the magnetron is completed, for example, a process of supplying a power to the cathode 15 to form a carbonized layer on the surface of the filament 19 and an inspection process for confirming the operation. Even if a force is applied to 26, since the convex portion 27 a is in contact with the outer periphery of the external terminal 26, the movement of the cathode lead 16 is restricted by the gap S between the external terminal 26 and the through hole 28. . Therefore, since no force is applied to the portion of the sealing metal plate 23 to which the cathode lead 16 is fixed, the cathode 15 is not displaced from a predetermined position, the filament 19 is broken, and the operating characteristic is It can prevent the deterioration.

Further, the convex portion 27a corresponds to the external terminal 2
When the one-end opening 26a of No. 6 and the cathode lead 16 are connected, since it is formed at the farthest position on the through hole 28 from the portion of the sealing metal plate 23, a force is applied to the external terminal 26. Even if the pressure is applied, the movement of the cathode lead 16 can be reliably regulated by the convex portion 27a.

[0033]

According to the first aspect of the present invention, the cathode in which the filament is arranged on the central axis portion of the anode, the pair of cathode leads for supporting the cathode, and the outer periphery of the cathode lead are closely attached to the stem insulator. A sealing metal plate airtightly bonded to the surface of the vacuum container side, and an external terminal inserted into the through hole of the stem insulator and connected to the cathode lead, and the through hole on the outer periphery of the external terminal. Since a protrusion that abuts the inner surface of the magnetron is formed, the magnetron is completed in an assembly process, for example, a process of supplying a power to the cathode to form a carbonized layer on the surface of the filament, an inspection process for confirming the operation, etc. Even if a force is applied to the external terminal, the protrusion contacts the inner surface of the through hole,
The movement of the cathode lead is restricted by the gap between the external terminal and the through hole. Therefore, since no force is applied to the portion of the sealing metal plate to which the cathode lead is fixed, the cathode is not displaced from the predetermined position, the filament is broken, and further the operating characteristics are deteriorated. There is an effect such as prevention.

According to the second aspect of the present invention, the protrusion is located in the vicinity of the opening of the through hole facing the vacuum container when the external terminal and the cathode lead are connected. Since the portion is located farthest on the through hole from the portion of the sealing metal plate to which the cathode lead is fixed, even if a force is applied to the external terminal, the protrusion can move the cathode lead. Is reliably regulated, and the cathode does not shift from the predetermined position,
There is an effect that the filament can be prevented from being broken and the operating characteristics can be prevented from being deteriorated.

According to the third aspect of the present invention, the cathode in which the filament is arranged on the central axis portion of the anode, the pair of cathode leads for supporting the cathode, and the vacuum of the stem insulator in close contact with the outer periphery of the cathode lead are provided. A sealing metal plate hermetically bonded to the surface on the container side, and an external terminal inserted through the through hole of the stem insulator and connected to the cathode lead, and the outer surface of the external terminal on the inner surface of the through hole. Since a convex portion that abuts against the external terminal is formed, even if a force is applied to the external terminal during the assembly process until the magnetron is completed, the convex portion can move the cathode lead in the gap between the external terminal and the through hole. Regulated. Therefore, since no force is applied to the portion of the sealing metal plate to which the cathode lead is fixed, the cathode is not displaced from the predetermined position, the filament is broken, and further the operating characteristics are deteriorated. There is an effect such as prevention.

According to claim 4 of the present invention, the convex portion is
When the external terminal and the cathode lead are connected to each other, since the through hole is located in the vicinity of the opening facing the vacuum container, the convex portion is the portion of the sealing metal plate to which the cathode lead is fixed. From the farthest position on the through hole from, even if a force is applied to the external terminal, the convex portion surely regulates the movement of the cathode lead, and the cathode does not shift from a predetermined position, There is an effect that the filament can be prevented from being broken and the operating characteristics can be prevented from being deteriorated.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a magnetron showing a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of a main part in FIG.

FIG. 3 is a cross-sectional view taken along the line A-A ′.

FIG. 4 is a longitudinal sectional view of a magnetron showing a second embodiment of the present invention.

FIG. 5 is a vertical cross-sectional view of the stem insulator.

FIG. 6 is a cross-sectional view of a cathode portion of a conventional magnetron for a microwave oven.

7 is a cross-sectional view of the main parts in FIG.

[Explanation of symbols]

8 anode 24 Tubular metal container 20 Stem insulator 19 filament 15 cathode 16 cathode lead 23 Sealed metal plate 21 through holes 22 External terminal 22a protrusion

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Satoshi Nakai             2-5-3 Keihan Hondori, Moriguchi City, Osaka Prefecture             Within Yo Denki Co., Ltd. (72) Inventor Noriyuki Okada             2-5-3 Keihan Hondori, Moriguchi City, Osaka Prefecture             Within Yo Denki Co., Ltd. (72) Inventor Setsuo Hasegawa             2-5-3 Keihan Hondori, Moriguchi City, Osaka Prefecture             Within Yo Denki Co., Ltd. F term (reference) 5C029 HH02 HH03

Claims (4)

[Claims] 1. A tubular metal container that is airtightly joined to an anode to form a part of a vacuum container, a stem insulator to which an open end of the tubular metal container is airtightly joined, and a center of the anode. A cathode in which a filament is arranged on a shaft portion, a pair of cathode leads that support the cathode, a sealing metal plate that is in close contact with the outer periphery of the cathode lead and is airtightly bonded to the surface of the stem insulator on the vacuum container side, A magnetron having an external terminal inserted through a through hole of the stem insulator and connected to the cathode lead, wherein a protrusion that abuts an inner surface of the through hole is formed on an outer periphery of the external terminal. And magnetron. 2. The magnetron according to claim 1, wherein the protrusion is located near an opening of the through hole facing the vacuum container when the external terminal and the cathode lead are connected. . 3. A cylindrical metal container which is airtightly bonded to the anode and constitutes a part of a vacuum container, a stem insulator whose opening end of the cylindrical metal container is airtightly bonded to the periphery thereof, and a center of the anode. A cathode in which a filament is arranged on a shaft portion, a pair of cathode leads that support the cathode, a sealing metal plate that is in close contact with the outer periphery of the cathode lead and is airtightly bonded to the surface of the stem insulator on the vacuum container side, A magnetron having an external terminal inserted through a through hole of the stem insulator and connected to the cathode lead, wherein a convex portion that abuts an outer periphery of the external terminal is formed on an inner surface of the through hole. And magnetron. 4. The magnetron according to claim 4, wherein the convex portion is located in the vicinity of an opening of the through hole facing the vacuum container when the external terminal and the cathode lead are connected. .