JP2003016952A - Magnetron - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetron hardly deformed even when force is applied to an external terminal for feeding power to a filament. SOLUTION: An external terminal 22 connected to a cathode lead 16 is formed of a cylindrical metal body opened at both ends. One end opening 22a of the cylindrical metal body is inserted and connected to the cathode lead 16, and the other end opening 22b is crushed and formed into a plate shape.

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. 9 is a sectional view of a cathode portion of a conventional magnetron for a microwave oven.

In FIG. 1, a filament 100 made of thorium tungsten is sandwiched between a top hat 101 and an end hat 102 made of molybdenum, and is supported by a pair of cathode leads 103 and 104 extending from the top hat 101 and the end hat 102. ing.

Then, the cathode leads 103, 104
Is fixed to the sealing metal plate 106 that is airtightly bonded to the stem insulator 105 made of ceramic, and the stem insulator 10
5, the external terminal 107 inserted through the through hole 105a
It is joined to the cathode leads 103 and 104.

By the way, the external terminal 107 is formed of a hollow cylindrical pipe whose both ends are opened. The opening on one end side is inserted into the cathode leads 103 and 104 to be joined, and the opening on the other end side is A connecting portion 107a for connecting the choke coil 108 for noise suppression is formed.

However, in this configuration, the external terminal 10
Since the connecting portion 107a of No. 7 is formed only by the thickness portion of the material, it may be bent when a force is applied to this connecting portion 107a during the assembly process, so that the power supply to the filament 100 and the choke coil 108 cannot be connected. There was a problem such as.

As a countermeasure against this, it is conceivable to increase the material thickness, but since the through hole 105a of the stem insulator 105 also becomes larger by increasing the tube diameter, the through hole 10
The joint area between the sealing metal plate 106 and the stem insulator 105, which are hermetically joined to the peripheral edge of the 5a, is reduced, and there is a concern that the hermetically joined portion may be broken in vacuum. This is the sealing metal plate 1
Although it can be solved by increasing 06 to widen the bonding area, generally, the cylindrical metal container 109 is set to the ground potential, whereas the filament 100, the cathode lead 103, 10
The cathode part composed of 4 etc. has a negative value of, for example, 4 k
Since a high voltage of V is applied to operate, the stem insulator 1
The creepage distance between the end of the cylindrical metal container 109 brazed to the metallized surface around 05 and the sealing metal plate 106 becomes short, and discharge easily occurs. Therefore, when trying to increase the creepage distance, the stem insulator 105 and the tubular metal container 1
09 became large, which led to an increase in size of the magnetron.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetron which is difficult to be deformed even when a force is applied to an external terminal for feeding a filament.

[0009]

According to the present invention, a cylindrical metal container which is airtightly bonded to an anode part and constitutes a part of a vacuum container, and an open end of the cylindrical metal container is airtightly bonded to the periphery thereof. A stem insulator, a cathode in which a filament is arranged on the central axis portion of the anode portion, a pair of cathode leads supporting the cathode, and a surface of the stem insulator that is in close contact with the outer circumference of the cathode lead and is on the vacuum container side surface. A magnetron comprising an airtightly sealed metal plate and an external terminal inserted from a through hole of the stem insulator and connected to the cathode lead, wherein the external terminal is composed of a metal cylinder having openings at both ends. The one end opening of the metal cylinder is inserted into and connected to the cathode lead, and the other end opening is formed by crushing into a flat plate shape.

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 applied to the cathode shaft, the electrons emitted from the filament are rotated by the power supplied from the external terminal. The rotating electrons oscillate by emitting microwaves in synchronization with the high frequency electric field of the anode part.

Since the other end opening of the external terminal is crushed into a flat plate to increase its thickness, an assembly process until the magnetron is completed, for example, power is supplied to the cathode to carbonize the surface of the filament. Even when a force is applied to the external terminal in the step of forming a layer, the inspection step of confirming the operation, etc., the external terminal is not bent, and power can be reliably supplied to the cathode. Further, by reducing the thickness of the external terminal, the outer diameter of the external terminal and the through hole are reduced, so that the magnetron is not increased in size, and in addition, it is airtightly joined to the peripheral edge of the through hole. Since a sufficient bonding area can be secured between the sealing metal plate and the stem insulator, it is possible to prevent vacuum breakage of the airtight bonding portion due to the progress of oxidation.

Further, since the other end opening is formed by bending, the end of the choke coil for suppressing noise is engaged with the bent portion, and the choke coil and the external terminal are connected. Connection can be secured.

Further, a tubular metal container which is airtightly joined to the anode part and constitutes a part of the vacuum container, a stem insulator in which an open end of the tubular metal container is airtightly joined to the periphery thereof, and the anode part A cathode having a filament arranged on the central axis of the core, a pair of cathode leads supporting the cathode, and a sealing metal plate that is in close contact with the outer circumferences of the cathode leads and is airtightly bonded to the surface of the stem insulator on the vacuum container side. A magnetron having an external terminal inserted through the through hole of the stem insulator and connected to the cathode lead, wherein the external terminal is composed of a metal cylinder having openings at both ends,
The through hole is formed of a large diameter portion and a small diameter portion, the cathode lead is inserted from the small diameter portion to the large diameter portion, and is joined to the external terminal at the large diameter portion. To do.

With the above structure, since the thickness increases by increasing the outer diameter of the external terminal, an assembly process until the magnetron is completed, for example, power is supplied to the cathode to form a carbonized layer on the surface of the filament. Even when a force is applied to the external terminal in a process, an inspection process for confirming an operation, etc., the external terminal is not bent, and power can be reliably supplied to the cathode. Further, since only the cathode lead is inserted into the small-diameter portion, it is not necessary to increase the diameter of the small-diameter portion even if the outer diameter of the external terminal is large, so that the magnetron is not enlarged. In addition, a sufficient bonding area can be secured between the sealing metal plate and the stem insulator, which are airtightly bonded to the peripheral edge of the through hole, so that vacuum break of the airtight bonding portion due to progress of oxidation can be prevented.

Further, since the abutment portion with which the one end opening portion of the external terminal abuts is formed in the large diameter portion, when the external terminal is inserted into the large diameter portion, the one end opening portion is Since it abuts on the abutting portion, the positioning in the height direction can be performed with a simple structure without providing a jig component for positioning.

Further, since the brazing material is interposed between the one end opening of the external terminal and the abutting portion, the cathode lead and the external terminal are securely joined by brazing. be able to.

Further, since the external terminal is formed by rolling a metal steel plate into a cylindrical body, when the material of the cylindrical body is used, when it is cut into a predetermined length, chips are projected into the opening. Since it becomes easier, this chip removal processing step is necessary, but since a steel plate can be easily processed with a die, the generation of chips can be suppressed.

Further, since the surface of the metal steel sheet is provided with a metal layer, when the material of the cylindrical body is used, even if the metal layer can be provided on the outer peripheral surface, the inner peripheral surface can be formed. Since it is difficult to apply a metal layer to the surface, corrosion due to rust or the like occurs at the inner peripheral portion. However, if a steel plate is used, it is possible to apply a metal layer to the entire surface in advance, so even if it is formed into a cylindrical body, the metal layer is applied to the inner peripheral surface, and corrosion due to rust etc. can be suppressed. .

[0019]

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 an essential part in FIG. 1, and FIG. 3 is an enlarged sectional view showing an enlarged part of the same. 4 is a vertical cross-sectional view of the external terminal.

Reference numeral 1 denotes a magnetron main 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 is a magnetron anode, which is made of oxygen-free copper and constitutes an anode cylinder 9 that constitutes a part of the vacuum wall of the main body 1, and radially inside 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 denotes a ring-shaped permanent magnet arranged above and below the anode 8, and a magnetic field of the permanent magnet 13 is provided to a tip of the vane 10 and a cathode 15 to be described later provided at the center of the anode cylinder 9. Each of the pole pieces 14 is provided for concentrating in the working space between them.

Reference numeral 15 denotes a cathode composed of a filament 19 sandwiched between 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 having a surface plated with nickel (in this embodiment, a metal steel plate having a material thickness of 0.25 mm), and one end opening of the external terminal 22. 22a is the cathode lead 16
And then joined by brazing, and the other end opening 22
b is formed by crushing into a flat plate shape. The crushed portion is formed with a bent portion 22c which is bent in the direction of the stem insulator 20, and the end portion of the choke coil 6 is joined to the bent portion 22c by welding. With this configuration, the bent portion 22c has a double thickness because two steel plates overlap each other (in the present embodiment, the thickness is 0.5 m).
m), for example, in the step of forming a carbonized layer on the surface of the filament 19 by supplying electric power to the cathode 15, the inspection step for confirming the operation, etc., there is no bending even if force is applied to the bent portion 22c. .

Reference numeral 23 is a sealing metal plate for sealing the entry of outside air from the external terminal 22 side.
Electrically separates the cathode leads 16 from each other,
The joint portion formed on the peripheral edge of the through hole 21 is hermetically joined by brazing.

Reference numeral 24 denotes a cylindrical metal container which is airtightly bonded to the anode 8 and constitutes a part of a vacuum container, and the opening end of the cylindrical metal container 24 has a cylindrical metal container 24 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 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.

Numeral 26 is a gap formed by the side wall of the cathode lead 16, the end of the outer lead 22, the stem insulator 20, and the lower surface of the sealing metal plate 23. Even if the external terminal 22 is touched and pressed to the sealing metal plate 23 side, by forming the gap 26, the sealing metal plate 26 is pushed up until it is separated from the stem insulator 20. I try not to.

With the above structure, the thickness of the other end opening 22b of the external terminal 22 is increased by crushing it into a flat plate shape, so that the step of supplying power to the cathode 15, for example, a carbonized layer on the surface of the filament 19 is performed. The other end opening 22 in the step of forming
Even if a force is applied to b, it will not bend, and power supply to the cathode 15 can be ensured. Further, by reducing the thickness of the external terminal 22, the outer diameter of the external terminal 22 and the through hole 21 are reduced, so that the magnetron is not increased in size, and in addition, the periphery of the through hole 21 is hermetically sealed. Since a sufficient bonding area can be secured between the sealing metal plate 23 and the stem insulator 20 to be bonded, it is possible to prevent vacuum breakage of the airtight bonding portion due to progress of oxidation. Further, the bent portion 22c can engage the end portion of the choke coil 6, and the connection between the choke coil 6 and the external terminal 22 can be ensured.

Further, since the external terminal 22 is formed by rolling a metal steel plate into a cylindrical body, the external terminal 22 can be easily processed with a die and the generation of chips can be suppressed.

Further, since a metal steel plate having a surface coated with a metal layer in advance is used, the metal layer is provided on the inner peripheral surface of the external terminal 22 even if it is formed into a cylindrical body, and rust, etc. It is possible to suppress corrosion due to.

Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 5 is a longitudinal sectional view of a main part of a magnetron showing a second embodiment of the present invention, FIG. 6 is an enlarged sectional view of an enlarged main part in FIG. 5, FIG. 7 is a sectional view of a stem insulator, and FIG. FIG. 5 is a vertical cross-sectional view of an external terminal. 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 27 is an external terminal formed in a cylindrical body by a metal steel plate whose surface is plated with nickel.
As the metal steel plate at this time, a thick metal steel plate (a steel plate having a material thickness of 0.5 mm in this embodiment) is used so as not to be deformed even when a force is applied, so that the metal steel plate has a large outer diameter. There is. Then, one end opening portion 27a of the external terminal 27
Is inserted into the cathode lead 16 and melted with a brazing material 29 described later to be joined by brazing.
b is connected by inserting the end portion of the choke coil 6. With this configuration, for example, in the step of forming a carbonized layer on the surface of the filament 19 by supplying power to the cathode 15, the inspection step of confirming the operation, etc., force is applied to the other end opening 27b of the external terminal 27. It never bends. Further, since both end openings 27a and 27b of the external terminal 27 have substantially the same diameter, it is not necessary to confirm the directionality of the external terminal 27 at the time of assembly, and the productivity is improved.

Reference numeral 28 denotes a through hole through which the cathode lead 16 and the external terminal 27 are inserted, and a step is formed in the through hole 28, and the large diameter portion 28 having a large inner diameter is formed by this step.
a and a small diameter portion 28b smaller than the inner diameter of the large diameter portion 28a are formed, and the cathode lead 16 has the small diameter portion 2a.
It is inserted from 8b to the large diameter portion 28a, and is joined to the external terminal 27 at the large diameter portion 28a. In addition, the external external terminal 27 is provided at the portion where this step is formed.
The external terminals 27 are arranged with a ring-shaped brazing material 29 having substantially the same diameter as the outer diameter of the outer terminals 27 interposed therebetween. The portion where the step is formed is referred to as an abutting portion 30, and the height direction of the external terminal 27 is positioned by abutting.

With the above-described structure, since the thickness increases by increasing the outer diameter of the external terminal 27, the step of supplying power to the cathode 15, for example, the step of forming a carbonized layer on the surface of the filament 19, the operation confirmation Even if a force is applied to the external terminal 27 in the inspection step or the like, the bending does not occur, and it is possible to reliably supply power to the cathode 15. Further, since only the cathode lead 16 is inserted into the small diameter portion 28b, the external terminal 27
Since it is not necessary to increase the diameter of the small diameter portion 28b even if the outer diameter of the sealing metal plate is increased, the magnetron is not increased in size, and the sealing metal plate is airtightly joined to the peripheral edge of the through hole 28. Since a sufficient bonding area between 23 and the stem insulator 20 can be secured, it is possible to prevent vacuum breakage of the airtight bonding portion due to progress of oxidation.

The external terminal 27 is connected to the first hole 28.
Since the one end opening 27a abuts the abutting portion 30 when inserted in a, the positioning in the height direction can be performed with a simple configuration without providing a positioning jig component.

The one end opening 27 of the external terminal 27
By interposing a brazing material between a and the contact portion 30, the cathode lead 16 and the external terminal 27 can be reliably joined by brazing.

Further, since the external terminal 27 is formed into a cylindrical body by rolling a metal steel plate, it can be easily processed with a die and the generation of chips can be suppressed.

Furthermore, since a metal steel plate having a metal layer applied on the surface is used, the metal layer is applied to the inner peripheral surface of the external terminal 27 even if it is formed into a cylindrical body. It is possible to suppress corrosion due to.

[0043]

According to the first aspect of the present invention, a pair of cathode leads for supporting the cathode, and a sealing metal plate that is in close contact with the outer circumference of the cathode leads and is airtightly joined to the surface of the stem insulator on the vacuum container side. And an external terminal inserted into the through hole of the stem insulator and connected to the cathode lead, wherein the external terminal is composed of a metal cylinder having openings at both ends, and one end opening of the metal cylinder has the cathode. Since the other end opening is inserted and connected to the lead and the other end opening is crushed into a flat plate shape, the other end opening of the external terminal increases in thickness by being crushed into a flat plate shape. Even if a force is applied to the opening at the other end, it does not bend. Therefore, the power supply to the cathode can be ensured, and the outer diameter and the through hole of the external terminal can be reduced by reducing the thickness of the external terminal. Since the bonding area between the sealing metal plate that is airtightly bonded to the peripheral edge of the through hole and the stem insulator is sufficient, it is possible to prevent vacuum breakage of the airtight bonding portion due to progress of oxidation.

According to the second aspect of the present invention, since the other end opening is formed by bending, the end of the choke coil for suppressing noise is engaged with the bent portion, and the choke coil and the external portion are engaged. The effect that the connection with the terminal can be surely achieved.

According to a third aspect of the present invention, a pair of cathode leads for supporting the cathode, and a sealing metal plate that is in close contact with the outer circumference of the cathode leads and is airtightly joined to the surface of the stem insulator on the vacuum container side, Inserted from a through hole of the stem insulator, an external terminal connected to the cathode lead is provided, and the external terminal is composed of a metal cylindrical body having openings at both ends,
The through hole is formed of a large diameter portion and a small diameter portion, and the cathode lead is inserted from the small diameter portion to the large diameter portion, and is joined to the external terminal at the large diameter portion. Since increasing the outer diameter of the terminal increases the thickness, it will not bend even if force is applied to the external terminal during the assembly process until the magnetron is completed, and it is possible to reliably supply power to the cathode. . Further, even if the outer diameter of the external terminal increases, the diameter of the small-diameter portion does not have to increase, so that the magnetron does not increase in size, and in addition, the seal that is airtightly joined to the peripheral edge of the through hole is used. Since a sufficient bonding area between the metal stopping plate and the stem insulator can be ensured, it is possible to prevent vacuum breakage of the airtightly bonded portion due to progress of oxidation.

According to the fourth aspect of the present invention, since the abutting portion with which the one end opening portion of the external terminal abuts is formed in the large diameter portion, the one end opening is inserted when the external terminal is inserted into the large diameter portion. Since the portion abuts on the abutting portion, there is an effect that the positioning in the height direction can be performed with a simple configuration without providing a jig component for positioning.

According to the fifth aspect of the present invention, since the brazing material is interposed between the one end opening of the external terminal and the abutting portion, the cathode lead and the external terminal are securely brazed. There is an effect that they can be joined.

According to claim 6 of the present invention, since the external terminal is formed by rolling a metal steel plate into a cylindrical body, the external terminal can be easily machined by a die and the generation of chips can be suppressed. Play.

According to claim 7 of the present invention, since the metal layer is formed on the surface of the metal steel sheet, the metal layer is formed on the inner peripheral surface even when formed into a cylindrical body, which may cause corrosion. It has the effect of suppressing corrosion.

[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 vertical cross-sectional view of the relevant part.

FIG. 3 is an enlarged cross-sectional view in which the main part is enlarged.

FIG. 4 is a vertical cross-sectional view of the external terminal.

FIG. 5 is a longitudinal cross-sectional view of a main part of a magnetron showing a second embodiment of the present invention.

FIG. 6 is an enlarged sectional view in which the main part is enlarged.

FIG. 7 is a cross-sectional view of the stem insulator.

FIG. 8 is a vertical cross-sectional view of the external terminal.

FIG. 9 is a vertical cross-sectional view of a main part of a conventional magnetron.

[Explanation of symbols]

8 anode 24 Tubular metal container 20 Stem insulator 19 filament 15 cathode 16 cathode lead 23 Sealed metal plate 21, 28 through holes 22, 27 External terminals 22a, 27a One end opening 22b, 27b Opening at the other end 28a Large diameter part 28b Small diameter part 30 Contact part 29 Brazing material

   ─────────────────────────────────────────────────── ─── 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. (72) Inventor Kiyota Taniguchi             2-5-3 Keihan Hondori, Moriguchi City, Osaka Prefecture             Within Yo Denki Co., Ltd. F term (reference) 5C029 HH03

Claims (7)

[Claims] 1. A tubular metal container which is airtightly joined to an anode part and constitutes a part of a vacuum container, a stem insulator in which an open end of the tubular metal container is airtightly joined to the periphery thereof, and the anode part. A cathode in which a filament is arranged on the central axis portion of the cathode, 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 In the magnetron, the external terminal is composed of a metal cylinder having openings at both ends, one end opening of the metal cylinder is inserted into and connected to the cathode lead, and the other end opening is formed by crushing into a flat plate shape. A magnetron that is characterized by 2. The magnetron according to claim 1, wherein the other end opening is formed by bending. 3. A tubular metal container which is airtightly joined to the anode part and constitutes a part of a vacuum container, a stem insulator to which the open end of the tubular metal container is airtightly joined to the periphery thereof, and the anode part. A cathode in which a filament is arranged on the central axis portion of the cathode, 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 In the magnetron, the external terminal is composed of a metal cylinder having openings at both ends, the through hole is formed of a large diameter portion and a small diameter portion, and the cathode lead is formed from the small diameter portion to the large diameter portion. A magnetron, characterized in that the magnetron is inserted over and is joined to the external terminal at the large diameter portion. 4. The abutment portion with which the one end opening of the external terminal abuts is formed in the large diameter portion.
The described magnetron. 5. A brazing material is interposed between the one end opening of the external terminal and the abutting portion.
The described magnetron. 6. The magnetron according to claim 1, wherein the external terminal is formed by rolling a metal steel plate into a cylindrical body. 7. The magnetron according to claim 6, wherein a metal layer is provided on a surface of the metal steel plate.