JP2008251201A - Magnetron - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly reliable product by suppressing the unnecessary radiation and leakage of the microwave energy of a fundamental wave to a power supply side from a magnetron input side which arise from a product variation, and a preferential structure for productivity. <P>SOLUTION: A metal plate is formed into a hat shape projecting to an interaction space side, a half of its bottom is airtightly brazed to a metallized part of a stem for deriving a cathode terminal, the remaining half of the bottom forms a shape having no bottom so that it is not brought into contact with a lead wire which is not electrically and directly connected to the bottom side, its hat-shaped first and second metal plates 42, 43 the halves of which have no bottom are formed so that a bottomless part at the right side is reversed to that at the left side, and the metal plates are disposed so as to cover the same axis with their drawn parts having shapes with different inner diameters. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a magnetron used for microwave heating equipment such as a microwave oven or an industrial microwave oscillator, and more particularly to a structure for suppressing microwave energy input to a magnetron.

  FIG. 8 is a longitudinal sectional view of a conventional magnetron, and FIG. 9 is a longitudinal sectional view of an essential part thereof. The magnetron 1 includes a filament 3 located on the central axis, an anode cylinder 5 that coaxially surrounds the filament 3, an input side magnetic pole piece 7 provided at an open end below the anode cylinder 5, A cathode terminal derivation stem 31 protruding from the first metal tube 9 covering the input side magnetic pole piece 7, an output side magnetic pole piece 13 provided at the open end above the anode cylinder 5, and this output side magnetic pole A second metal tube 15 covering the piece 13 and a microwave emission antenna 19 protruding from the second metal tube 15 via an insulating tube 17 made of ceramics are provided.

  A plurality (even number) of anode vanes 20 are joined to the inner wall surface of the anode cylinder 5 radially toward the central axis of the anode cylinder 5. At the upper and lower end edges of each anode vane 20, a ring engaging recess 20 a for joining the pressure equalizing ring and a ring insertion recess 20 b for inserting the pressure equalizing ring in a non-contact manner are positioned in the radial direction of the anode cylinder 5. And the arrangement of the upper edge and the lower edge is reversed.

  The anode vanes 20 arranged in the circumferential direction are either one of the two pressure equalizing rings 22 and 24, which are a small diameter equalizing ring 22 and a large diameter equalizing ring 24 arranged concentrically with the central axis of the anode cylinder 5. Are joined to the ring engaging recess 20a and electrically connected every other sheet.

  The first annular permanent magnet 21 made of ferrite stacked on the outer end face of the input side pole piece 7 in a ring shape surrounding the first metal tube 9 has one magnetic pole magnetically connected to the input side pole piece 7. Combined with Further, the second annular permanent magnet 23 made of ferrite stacked in a ring shape surrounding the second metal tube 15 on the outer end face of the output side magnetic pole piece 13 has one magnetic pole at the output side magnetic pole piece 13. Magnetically coupled.

  The frame upper yoke 25 for magnetically coupling the other magnets of the first and second annular permanent magnets 21 and 23 is a passage through which the cathode terminal derivation stem 31 is inserted into the lower end portion. It has a hole 25a.

  In addition, a large number of radiating fins 27 are attached to the outer peripheral surface of the anode cylinder 5 in a multistage manner, and the outer surface of the lower end portion of the frame upper yoke 25 is made of a metal for preventing leakage of electromagnetic waves leaking from the device. A filter terminal 29 is attached, and a cathode terminal derivation stem 31 having a diameter smaller than that of the through hole 25a of the frame upper yoke 25 is airtightly brazed to the first metal tube 9, and the inside of the cathode terminal derivation stem 31 is inside. Are inserted through the cathode terminals 11a and 12a and are electrically connected to the lead wires 11 and 12 through the metal plates 11b and 12b.

  A through-type capacitor 33 is attached to the side surface of the filter case 29, and one end of the choke coil 35 is connected to the cathode terminals 11 a and 12 a of the cathode terminal derivation stem 31 located in the filter case 29. ing. The other end of the choke coil 35 is connected to the through electrode of the capacitor 33 so as to constitute an LC filter circuit for preventing leakage electromagnetic waves.

  In the magnetron 1 configured as described above, the choke ring 37 having an axial length of about ¼ wavelength is used as the second metal tube in order to suppress harmonic noise leaked to the microwave emission antenna 19 side. 15 is airtightly brazed.

In such a structure, the lead wires 11 and 12 serve as antennas, and fundamental wave microwave energy in the 2455 MHz band and unnecessary radiation noise other than the fundamental wave leak from the cathode side. In order to reduce unnecessary radiation noise, a high dielectric constant member and a metal tubular choke member are arranged in this order on the inner surface of the metal tube, and the choke member is electrically connected to one of a pair of lead wires. The structure which was made was invented (for example, refer patent document 1). If the fundamental microwave energy is suppressed and unnecessary radiation noise is reduced, the number of parts increases and the structure becomes complicated, resulting in an increase in cost and a decrease in productivity.
JP 2003-45347 A

  However, in the conventional magnetron as shown in FIGS. 8 and 9, unnecessary radiation in the 400 MHz to 800 MHz band and the microwave energy of the fundamental wave are reduced by the empty turn portion of the choke coil of the LC filter circuit. Variations in the length of the coil from the connection terminal to the empty turn due to variations in welding between the coil and the connection terminal, resulting in a change in the reflection phase point at the empty turn, resulting in increased unwanted radiation, and further A lot of microwave energy was leaked.

  Although the structure of Patent Document 1 can reduce unnecessary radiation and fundamental wave microwave energy, the number of parts increases and the structure becomes complicated, resulting in an increase in cost and a decrease in productivity.

  In view of the above-described problems, an object of the present invention is to provide a highly reliable magnetron that can stably and easily reduce unwanted radiation and fundamental microwave energy.

  In order to achieve the above object, according to a first aspect of the present invention, an active space is formed between an anode structure in which a plurality of vanes are formed in a central direction and the vane disposed on the central axis. The cathode assembly includes a spiral filament, first and second end hats provided at both ends of the filament, and a tip end fixed to the first end hat. A first lead wire penetrating the second end hat without contact, and a second lead wire having a tip fixed to the second end hat, the first and second lead wires being a cathode Soldered to the respective metal plates on the insulator upper surface metallization of the terminal lead stem, the connection terminals are airtightly brazed to the metal plates, and the first and second lead wires are the respective metal plates. Through In the magnetron that is electrically connected to each connection terminal, the metal plate forms a cap shape that protrudes to the working space side, and about half of its bottom is brazed in an airtight manner with the metallization of the cathode terminal lead-out stem. The other half of the bottom is shaped so that it does not have a bottom so that it does not come into contact with the lead wire that is not directly electrically connected. It has a configuration in which the shape is reversed and is arranged so as to be coaxially covered with a shape in which the inner diameter of the throttle portion is different.

  According to such a configuration, unnecessary radiation and fundamental microwave energy can be stably and easily reduced without increasing the cost.

  According to the second aspect of the present invention, the half-bottomless cap-shaped metal plate is deep-drawn with an iron material, and airtight brazing with the insulator upper surface metallization of the cathode terminal lead stem is performed on the cathode terminal lead stem. A material having a smaller thermal expansion coefficient than an iron material having the same thermal expansion coefficient is interposed therebetween.

  According to such a configuration, unnecessary radiation and fundamental microwave energy can be more stably and easily reduced.

  Further, the invention described in claim 3 is a microwave utilization device provided with the magnetron described in claim 1 or claim 2.

  According to such a configuration, it is possible to cope with the suppression of the fundamental microwave energy and the suppression of unnecessary radiation to the input unit, and it is possible to obtain a highly reliable microwave using device.

  As described in detail above, according to the first aspect of the present invention, the metal plate connecting the lead wire and the connection terminal forms a cap shape protruding toward the working space, and about half of the bottom of the metal plate is led out of the cathode terminal. Stem metallization, airtightly brazed to connection terminals and lead wires, and the other half of the bottom is shaped so that it does not come into contact with the other lead. It cancels out and the microwave energy of the fundamental wave can be reduced. Further, since two half-bottomed cap-shaped metal plates are coaxially arranged with different shapes of lead wires that do not contact, the microwave energy of the fundamental wave can be drastically reduced by a synergistic effect.

  Further, since the first and second metal plates having a half bottomless cap shape are arranged so as to cover the same axis with different inner diameters of the throttle portions, a capacitor is connected between them. Accordingly, the normal mode noise generated inside the magnetron is attenuated and absorbed by the capacitor from the pair of lead wires on the cathode side, so that leakage of unnecessary radiation to the power source side can be prevented. Furthermore, with regard to common mode noise, if the input side metal tube is placed close to the surface other than the half-bottomed hat-shaped bottomed portion, a capacitor is connected between the lead wire and ground, and the common mode noise Leakage to the power supply side can be prevented.

  In terms of the structure, there is no welding between the lead wire made of molybdenum and the choke member, and all the parts are connected by brazing. Therefore, the manufacturing is extremely easy and the mass productivity is remarkably improved.

  As described above, unnecessary radiation and fundamental microwave energy can be reduced stably and easily, and a highly reliable magnetron can be provided.

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

(Embodiment 1)
FIG. 1 is a longitudinal sectional view of a magnetron of the present invention. FIG. 2 is a longitudinal sectional view of the main part. The configuration shown in FIGS. 1 and 2 is different from the conventional configuration shown in FIGS. 8 and 9 in that the metal plate 42 is hermetically brazed to the connection terminals 11a and 12a on the metallization of the cathode terminal derivation stem 31. There are 43 shapes. Whereas the conventional metal plates 11b and 12b have a semicircular shape with an L-shaped cross section with a turn, the first metal plate 42 of the invention has a cap shape protruding toward the working space, and its bottom About half of the first lead is connected to the metallization of the cathode terminal lead-out stem 31 and the first connection terminal 11a in an airtight manner, and is electrically connected to the airtightly brazed first connection terminal 11a. The wire 11 is also brazed to the first metal plate 42. Further, the bottom portion of the remaining half of the first metal plate 42 has a half bottomless cap shape so as not to contact the second lead wire 12. Similarly, the second metal plate 43 has a shape in which the inner diameter of the throttle portion is different from that of the first metal plate 42, and the presence or absence of the bottom portion is opposite to that of the first metal plate 42. The first and second metal plates are arranged so as to cover the same axis, and have a structure that maintains a certain clearance so as not to be electrically short-circuited.

With the structure as described above, the metal plates 42 and 43 can suppress the microwave propagated from the input unit during the oscillation operation of the magnetron, and can suppress leakage to the power supply side. This is because the first half bottomless cap-shaped metal plate 42 is airtightly brazed to the first connection terminal 11 a and the first lead wire 11, and the remaining half of the bottom does not contact the second lead wire 12. Similarly, the second half-bottomless cap-shaped metal plate 43 is airtightly brazed with the second connection terminal 12 a and the second lead wire 12 and does not come into contact with the first lead wire 11. As described above, the continuous magnetic field is cut off by surrounding the lead wire in which the half-bottomless cap-shaped metal plate is not directly electrically connected, and the microwave energy of the fundamental wave is suppressed. Since the half bottomless hat-shaped metal plate is doubled, the effect is doubled, and leakage of the fundamental wave microwave energy to the power source side is Ef = 3.2 (V), Ib = 300 (mA), Eb = 4 (kV) without the filter circuit, the conventional 20 (mW / cm ² ) was reduced to 10 (mW / cm ² ).

  In addition, as described above, as a result of being coaxially arranged so as to cover the metal plate, a capacitance proportional to the surface area of the collar portion and the narrowed portion of the half-bottomless cap-shaped metal plate is generated, and the normal mode noise power source side Leakage can be prevented.

(Embodiment 2)
3 is a longitudinal sectional view of a main part of the magnetron according to the second embodiment of the present invention, and FIG. 4 is an assembled perspective view of the metal plate shown in FIG. In the deep drawing type shown in FIG. 3 and FIG. 4, a material suitable for deep drawing such as iron must be used. However, when metallization is performed directly, the temperature at the time of brazing is 800 (° C.). Since cracks occur due to the difference in thermal expansion between iron and ceramic until it returns to room temperature, it is used for the conventional metal plates 11b and 12b between the metallized and half-bottomed cap-shaped metal plates 42 'and 43'. The relay plates 44 and 45 made of the same material (example: 42% nickel-containing iron) are provided to ensure the reliability of the product. With the deep drawing amount 10 (mm) of this structure, leakage of the fundamental wave microwave energy to the power source side is Ef = 3.2 (V), Ib = 300 (mA), Eb = 4 (kV). In the state without the filter circuit, it is drastically reduced to 7 (mW / cm ² ) and an electrostatic capacity of 11 (pF) can be obtained, and leakage of normal mode noise to the power supply side can be further prevented.

(Embodiment 3)
5 to 7 are longitudinal sectional views of main parts of the magnetron according to the third embodiment of the present invention.

  Furthermore, as shown in FIGS. 5 to 7, if metal pieces 46, 47, 48 having the same potential as the first metal tubes 9, 9 ′ are provided between the half-bottomless cap-shaped metal plates, the common mode noise can be prevented. Leakage can be prevented. In particular, a capacitance of 37 (pF) can be obtained with a deep drawing (10 mm) type metal plate interval 0.5 (mm) shown in FIG. 7, and leakage of common mode noise to the power supply side can be suppressed. It was.

  In the conventional magnetron, the leakage of unnecessary radiation to the power supply side is suppressed by the L-C filter circuit of the choke coil 35 and the capacitor (400 pF) 33. However, the capacitance of 10 (pF) or more is present inside the magnetron. If it is obtained, the function as a CLC filter circuit is sufficiently exhibited, and leakage of unnecessary radiation can be suppressed even with a bypass capacitor having a relatively small capacitance.

  The present invention relates to input part propagation microwave energy and unwanted radiation suppression of a magnetron apparatus used for microwave heating equipment such as a microwave oven.

  The half-bottomless hat-shaped metal plate of the present invention can cope with suppression of fundamental microwave energy and unnecessary radiation to the input part, and is excellent in reliability. Therefore, microwave heating equipment such as a microwave oven or industrial microwave Effective for applications such as oscillators.

1 is a longitudinal sectional view of a magnetron configuration according to Embodiment 1 of the present invention. Main part longitudinal cross-sectional view of the magnetron in Embodiment 1 of this invention Partial configuration sectional view of a magnetron in Embodiment 2 of the present invention Assembly perspective view of the metal plate shown in FIG. Main part longitudinal cross-sectional view of the magnetron in Embodiment 3 of this invention Main part longitudinal cross-sectional view of the magnetron in Embodiment 3 of this invention Main part longitudinal cross-sectional view of the magnetron in Embodiment 3 of this invention Vertical section of a conventional magnetron Longitudinal section of the main part of a conventional magnetron

Explanation of symbols

2 First end hat 3 Filament 4 Second end hat 11 First lead wire 12 Second lead wire 11a First connection terminal 12a Second connection terminal 20 Bain 31 Cathode terminal lead stem 42 of the present invention First metal plate 43 Second metal plate of the present invention

Claims (3)

An anode structure in which a plurality of vanes are formed in a central direction, and a cathode structure that is disposed on the central axis and forms a working space between the vanes. The cathode structure includes a spiral filament and the filament. First and second end hats provided at both ends of the first end hat, and a first lead that is fixed to the first end hat and penetrates the second end hat without contacting the filament And a second lead wire having a tip fixed to the second end hat, and the first and second lead wires are made of respective metals on the insulator upper surface metallization of the cathode terminal lead stem. The connection terminals are brazed airtightly to the metal plate, and the first and second lead wires are electrically connected to the connection terminals via the respective metal plates. In the netron, the metal plate has a cap shape protruding to the working space side, and about half of the bottom is airtightly brazed with the metallization of the stem for leading out the cathode terminal, and the other half of the bottom is electrically The first and second metal plates, which are half-bottomless caps, have opposite bottoms, and the inner diameter of the throttle part A magnetron characterized by being arranged on the same axis in different shapes. The half-bottomless cap-shaped metal plate is made of a deep drawn shape with an iron material, and the airtight brazing with the insulator upper surface metallization of the cathode terminal derivation stem is equivalent to the thermal expansion coefficient of the cathode terminal derivation stem. 2. The magnetron according to claim 1, wherein a material having a smaller thermal expansion coefficient is interposed therebetween. A microwave using device comprising the magnetron according to claim 1.

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