JP3397276B2 - Anode for flat type magnetron and flat type magnetron - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat plate type magnetron anode used in a high frequency heating apparatus such as a microwave oven and a method for manufacturing the same.

[0002]

2. Description of the Related Art A magnetron is one of the crossed field devices in which a DC magnetic field and a DC electric field which are perpendicular to each other exist in an action space in an electron tube, and is characterized by a high efficiency of about 70%. .

FIG. 7 is a partial longitudinal sectional view of a conventional cylindrical magnetron. As shown in FIG. 7, the cylindrical anode 11
1, a plurality of vanes 112 are radially formed toward the center, and the anode 111 and the vanes 112 form a cavity resonator. The cathode 113 is arranged on the central axis of the cylindrical anode 111. A space between the cathode 113 and the vane 112 serves as an action space for electrons to move due to the electromagnetic field.

A magnet 116 for forming a uniform magnetic field in the working space is provided with an anode 11 via a pole piece 114.
The yokes 115 are attached to the upper and lower ends of the magnet No. 1, and a yoke 115 is provided so as to surround the upper and lower magnets 116 in order to form a closed magnetic field. Further, a heat dissipation plate 117 for dissipating heat generated by the anode loss is arranged between the anode 111 and the yoke 115. Anode loss is cathode 1
The electrons emitted from 13 are accelerated by the anode voltage,
It is generated by colliding with 11.

In such a structure, the inside of the anode 111 is evacuated, a magnetic field is applied to the working space by the magnet 116, and a high voltage is applied between the cathode 113 and the vane 112 from the power supply input section 118. Electrons fly out from the toward the bain 112. The ejected electrons make a so-called cycloidal motion in which a magnetic field received from the magnet 116 advances toward the vane 112 while drawing a spiral in the action space. Energy is applied to the cavity resonator from these electrons, a high-frequency electric field is generated, and the microwaves are extracted from the microwave output section 119 as microwaves.

At present, a cylindrical magnetron is mainly used as a magnetron used in a high-frequency heating apparatus such as a microwave oven, but a flat plate magnetron intended for operation at a low voltage has also been proposed. FIG. 8 is a schematic vertical sectional view of a conventional flat plate magnetron, and FIG. 9 is an external perspective view of the flat plate magnetron of FIG. As shown in FIGS. 8 and 9, a plurality of vanes 122 are formed vertically on the flat plate-shaped anode 121 in the alumina ceramic housing 120 with respect to the cathode 123 and the sole portion 124 at the same pitch.
The anode 121 and the vane 122 form a cavity resonator. The cathode 123 is disposed below the left end of the flat plate-shaped anode 121, and the space sandwiched between the sole portion 124 and the vane 122 serves as an action space for electrons to move due to the electromagnetic field.

Further, as shown in FIG. 9, magnets 125 for forming a uniform magnetic field in the working space are attached to both sides of the anode 121 via pole pieces 126 to form a closed magnetic field. In order to do so, a yoke 127 is provided so as to surround the magnets 125 on both sides. Further, the yoke 127 is formed with a heat dissipation plate 128 for radiating heat generated by anode loss.

In such a structure, the inside of the electrode is evacuated, the magnetic field is applied to the working space by the magnet 125, and the anode 121, the sole portion 124 and the vane 122 are formed.
When a voltage is applied from the power input unit 130 in the meantime, the cathode 12
Electrons fly out from 3 toward the vane 122. Due to the magnetic field received from the magnet 125, the ejected electrons proceed to the right in FIG. 8 while performing a cycloidal motion in the action space as in the cylindrical magnetron. Energy is applied to the cavity resonator from these electrons, a high-frequency electric field is generated, and the microwaves are extracted from the microwave output section 129 as microwaves.

In any of the above magnetrons, in the case of a magnetron using a split anode, oscillation in various modes occurs depending on the number of splits. Among them, the mode actually used is called a π mode in which the phase transition between adjacent resonators is equal to π radian, and the interaction is strongest. However, in the oscillation of the magnetron, if the oscillation frequencies of the π mode and other modes are close to each other, a jump (mode-jumping) from the π mode to another mode occurs even if the operating condition changes slightly, As a result, the oscillation frequency and output suddenly change. Therefore, it is necessary to close the coupling between the resonators and separate the resonance frequencies of the respective modes as much as possible.

As a measure against these problems, the conventional magnetron separates modes by a pressure equalizing ring or the like.
The pressure equalizing ring is one in which every other anode vane is connected by a conductor. This forces the potential of every other anode to oscillate in the same phase. Therefore, the vibrating modes can be limited to the π mode and the 0 mode (all the anode vanes vibrate in the same phase).

[0011]

In the conventional cylindrical magnetron, the operating voltage is as high as about 4 kV,
There is a problem that a high voltage transformer is required for the driving. In order to drive this with a household power supply voltage of 100 V, it is necessary to make the pitch of the anode vanes fine or to reduce the applied magnetic field strength in terms of phase matching.
However, if the magnetic field strength is lowered, the oscillation capability will be significantly reduced. Therefore, it is necessary to deal only with making the pitch finer.

However, when the operating voltage is changed from 4 kV to 100 V, the pitch of the anode vanes becomes about 15% of the current one, and the machining becomes difficult as compared with the conventional anode. The oscillation frequency of the magnetron is determined by the resonance frequency of the anode cavity resonator.
This resonance frequency is also affected by the shape of the anode cavity resonator, but its size has a large effect. In particular, in a flat plate magnetron, the vanes are parallel to each other, and it is difficult to form an air gap to increase the capacitance and the inductance. Therefore, it is necessary to increase the groove depth of the cavity resonator. For example, in the case of operating voltage of 100 V, in order to oscillate at the frequency of 2.45 GHz used for high frequency heating, the cavity width is 0.1 mm to 0.25 mm and the vane height (groove depth) is Therefore, there is a problem that the pitch may be deviated due to the deformation of the vanes and the efficiency may be lowered. It is also difficult to attach conductors such as pressure equalizing rings to every other vane having such a fine pitch.

The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to prevent deformation of the vanes and to electrically connect every other vane. An object of the present invention is to provide a flat plate type magnetron anode and a flat plate type magnetron which can improve the oscillation efficiency and can be easily and accurately processed.

[0014]

According to a first aspect of the present invention, a plurality of flat plate-shaped vanes are erected in a row at the same pitch, and the vanes are alternately displaced in a direction perpendicular to the arrangement direction. A flat-plate magnetron anode, in which the upper part of one flat plate surface of the anode is a plurality of vertically-arranged ones.
Of the plate-shaped vanes, the lower end is formed by the end faces of the odd-numbered vanes and the lower end is formed by the end faces of the even-numbered vanes.
The upper part of the other flat plate surface of the anode is formed by the end faces of the even-numbered vanes, and the lower part is formed by the end faces of the odd-numbered vanes, and the flat conductor is mechanically and electrically formed on both flat plate faces of the anode. It is a flat plate type magnetron anode characterized by being joined.

According to a second aspect of the present invention, in the first aspect, the conductor is mechanically and electrically joined only to the end faces of the odd-numbered vanes, and the equalizing plate is attached only to the end faces of the even-numbered vanes. A flat plate type magnetron anode comprising a pressure equalizing plate mechanically and electrically joined.

According to a third aspect of the present invention, in the first aspect , the groove processing for forming the vane end face on both flat plate surfaces of the anode is performed.
It is a flat plate type magnetron anode characterized by being forged or combined with a multi-wire saw and brazing.

According to a fourth aspect of the present invention, there is provided a flat plate type magnetron anode in which a plurality of flat plate-shaped vanes are erected in a line at the same pitch and the vanes are alternately displaced in a direction perpendicular to the arrangement direction. Then, the upper part of one plate surface of the anode is covered with a plurality of plate-shaped vanes standing in a line.
Then, the lower part is formed by the end faces of the odd-numbered vanes and the lower part is formed by the end faces of the even-numbered vanes, and the upper part of the other flat plate surface of the anode is formed by the end faces of the even-numbered vanes and the lower part is the odd-numbered part. And an anode for a flat plate magnetron formed by the end face of the vane, and a housing for accommodating the anode and having a protrusion having a pitch twice the vane pitch formed at a position on the inner wall surface corresponding to the anode vane. And a flat plate type magnetron.

According to a fifth aspect of the present invention, in the flat magnetron according to the fourth aspect, the surface of the protrusion and the groove formed between the protrusions are coated with a conductor.

According to a sixth aspect of the present invention, in the fourth aspect , the groove processing for forming the vane end surface on both flat plate surfaces of the anode is performed.
It is a flat plate type magnetron that is performed by forging or a combination of a multi-wire saw and brazing.

[0020]

DETAILED DESCRIPTION OF THE INVENTION

(Embodiment 1) FIG. 1 is a perspective view showing an embodiment of a flat plate type magnetron anode according to the present invention. As shown in FIG. 1, the anode 1 has a structure in which a plurality of flat plate-shaped vanes 2 and 3 are erected in a row at the same pitch, and these vanes 2 and 3 are perpendicular to the arrangement direction. Alternate in different directions. That is, the odd-numbered vanes 2 and the even-numbered vanes 3 are alternately shifted in a direction perpendicular to the arrangement direction, and the upper part of one flat plate surface 1a of the anode 1 (3 mm from the tips of the vanes 2 and 3 is (Up to the position) is formed by the end surface 2a of the odd-numbered vane 2 and the lower part thereof is formed by the end surface 3b of the even-numbered vane 3. The upper portion of the other flat plate surface 1b of the anode 1 is formed by the end surface 3b of the even-numbered vane 3, and the lower portion thereof is formed by the end surface 2a of the odd-numbered vane 2.

Further, as shown in FIG. 1, a flat plate-shaped pressure equalizing plate 4 made of a conductor is joined to both flat plate surfaces 1a and 1b of the anode 1. That is, the pressure equalizing plate 4 attached to the upper part of the one flat plate surface 1a of the anode 1 is mechanically and electrically bonded only to the end surface 2a of the odd-numbered vane 2,
The pressure equalizing plate 4 attached to the lower portion of the flat plate surface 1a is mechanically and electrically joined only to the end surface 3b of the even-numbered vane 3. Further, the pressure equalizing plate 4 attached to the upper part of the other flat plate surface 1b of the anode 1 is an end surface 3b of the even-numbered vane 3.
Is mechanically and electrically joined only to the end face 2a of the vane 2 of odd number, and the pressure equalizing plate 4 attached to the lower portion of the flat plate surface 1b is joined mechanically and electrically.

Next, a method for processing the flat plate type magnetron anode will be described. FIG. 2 is a side view of the oxygen-free copper block for an anode which has been grooved. As shown in FIGS. 2A and 2B, both flat plate surfaces 5a of the oxygen-free copper block 5 for the anode,
The grooves 6a, 6b, 7a and 7b were formed in 5b by forging. The flat plate surface 5a of the copper block 5 corresponds to the flat plate surface 1a of the anode 1, and the flat plate surface 5b of the copper block 5 corresponds to the flat plate surface 1b of the anode 1. The size of the copper block 5 is 1 vertical
It is 0 mm x 60 mm wide x 35 mm high. Grooves 6a, 6b, 7
a and 7b are flat plate surfaces 5a and 5 having a width of 60 mm and a height of 35 mm.
It was prepared by processing b with a cutting margin of 0.3 mm and a depth of 1 mm at a pitch of 0.6 mm. The grooves 6a and 7b and the grooves 6b and 7a
The positions of and are shifted by 0.3 mm.

Then, a groove having a wire diameter of 0.13 mm and a cavity of 150 μm and a depth of 30 mm was machined at a total of 167 points by a multi-wire saw. And
1mm x 50 at 1mm and 3mm from the top of the copper block 5
A flat plate-shaped pressure equalizing plate 4 made of oxygen-free copper of mm was brazed with Au-Ge solder. This produced the anode 1 shown in FIG. In the present embodiment, as described above, the multi-wire saw is used for the fine pitch groove processing. The multi-wire saw is a solution (lapping liquid) in which a piano wire wound between pitched rollers has abrasive powder dispersed.
It moves while applying a groove, and performs grooving and cutting. Mainly used for processing magnetic heads, crystal oscillators, etc. Processing pitch of 0.3 mm and cutting allowance of about 120 μm are possible.

By the above-mentioned processing means, the vanes 2 and 3 are alternately displaced at a fine pitch in a direction perpendicular to the arrangement direction.
Since the anode 1 having a complicated shape having
The processing time can be shortened and the processing accuracy can be improved. Moreover, odd-numbered vanes 2 and even-numbered vanes 3
And the upper surface of one flat plate surface 1a of the anode 1 is formed by the end surface 2a of the odd-numbered vane 2, and the lower part is formed by the end surface 3b of the even-numbered vane 3, and the other flat plate of the anode 1 is formed. Since the upper part of the face 1b is formed by the end face 3b of the even-numbered vane 3 and the lower part thereof is formed by the end face 2a of the odd-numbered vane 2, the flat plate faces 1a, 1b of the anode 1 are respectively formed on the upper and lower parts thereof. By simply mounting the pressure equalizing plate 4, the alternate vanes 2 and 3 can be easily electrically connected on both sides.
As a result, the modes can be separated and the oscillation efficiency can be improved.

Furthermore, since the vanes 2 and 3 are fixed by joining the pressure equalizing plate 4 to the vanes 2 and 3, it is possible to prevent deformation of the vanes and a reduction in oscillation efficiency due to pitch deviation, and it is possible to prevent the vanes from being required in the past. Eliminates the need for holding spacers. Further, since heat conduction is improved by the pressure equalizing plate 4, it is possible to prevent deformation of the vane and thermal fluctuation of the magnetic field due to heat.

FIG. 3 is an exploded perspective view showing the structure of a flat plate magnetron using the anode obtained as described above. As shown in FIG. 3, a rod 19 for extracting a microwave output was brazed with a silver-copper braze at the center of one vane of the anode 1 and joined. Furthermore, in a vacuum container (10 ^-8 To
rr), the anode 1 was brazed with a gold-germanium braze to a housing 12 (metallized Kovar on the joint 12a) made of alumina ceramic to which the cathode 13 was die-bonded, and joined.

Pole pieces 14 for generating a required magnetic field in the working space are attached to both side surfaces of the housing 12. A heat sink 17 was provided on a galvanized iron yoke 15, and a ferrite magnet 16 was attached to the inside of the yoke 15. Finally, the yoke 15 was attached to the housing 12 so as to cover the housing 12, thereby completing the flat plate type magnetron.

An anode voltage of 100 V is applied to the completed flat plate type magnetron from the power supply input section 18, and an oscillation output of 2.45 GHz is generated under the conditions of a distance between the anode and the sole of 0.5 mm, a magnetic field strength of 1360 Gauss, and an emission current of 2.1 A. It was measured by a power meter. As a result, 162W
The oscillation output was obtained, and the oscillation output was improved.

(Embodiment 2) FIG. 4 is a perspective view showing one embodiment of a housing for accommodating a flat plate type magnetron anode. As shown in FIG. 4, on the inner wall surface of the alumina ceramic housing 32 of the flat plate type magnetron, the vane pitches of the vane pitches were formed at the positions corresponding to the vanes 2 and 3 of the anode 1 (without the pressure equalizing plate) manufactured in the first embodiment. A plurality of protrusions 30 having a double pitch were formed. That is, the comb-shaped structure including the plurality of protrusions 30 is configured such that the end faces 2a, 3a of the vanes 2, 3 of the anode 1 are fitted into each protrusion 30. Since this comb-shaped structure is built in the mold of the ceramic housing 32, it can be easily and accurately manufactured.

Next, the surface of the protrusion 30, the groove 30a formed between the protrusions 30, and the joint 3 of the housing 32 are joined together.
2a was metallized with silver. As shown in FIG. 5, the anode 1 is incorporated in the housing 32, and the upper protrusion 30 having a two-stage comb structure has upper vanes 2 and 3, and the lower protrusion 30 has lower vanes 2 and 3. Joined each. Finally, a flat plate type magnetron having the same structure as that shown in FIG. 3 was manufactured. Anode voltage of 100 V is applied to the manufactured flat plate magnetron from the power input part, and the oscillation output of 2.45 GHz is measured by the power meter under the conditions of the anode-sole distance of 0.5 mm, the magnetic field strength of 1360 Gauss, and the emission current of 2.1 A. did. As a result, 159
An oscillation output of W was obtained, and an oscillation output equivalent to that of the first embodiment was obtained.

(Embodiment 3) In the above-described Embodiment 1, the groove processing of the copper block performed by forging is performed by a multi-wire saw and brazing. FIG. 6 is a side view of an oxygen-free copper block for an anode which is grooved by another means. As shown in FIG. 6, the oxygen-free copper block 35 is vertically divided by A-A, and each of the copper blocks 35c, 35 is cut.
Groove processing was performed on each d using a multi-wire saw. The wire diameter was 0.28 mm, the abrasive grain was GC1000, and the cutting speed was 0.1 mm / min. The flat plate surface 35a of the copper block 35 is the flat plate surface 1a of the anode 1 in FIG.
In addition, the flat plate surface 35b of the copper block 35 is the flat plate surface 1 of the anode 1.
Each corresponds to b.

During this groove processing, the upper and lower blocks 35c,
The groove machining position was shifted by 0.3 mm at 35d. The bottom of the upper copper block 35c was silver-plated, and the upper copper block 35c and the lower copper block 35d were brazed at a position A-A in a nitrogen atmosphere at 900 ° C. to make an anode.
It was found that the grooving of this embodiment has the same level of accuracy (± 10 μm) as the forging. In the case of this groove processing, it was possible to prevent the generation of R at the groove position switching portion AA in FIG.

[0033]

According to the anode for a flat plate magnetron and the flat plate magnetron of the present invention, grooves are formed on both flat plates of the anode at positions above and below the vane pitch by shifting the position by a vane pitch before the cavity resonator is processed. By joining the vanes with a structure having grooves having a pitch twice the vane pitch after processing the cavity resonator, mechanical and electrical joining of the vanes can be easily achieved. Further, by holding each vane on both flat plate surfaces, it is possible to prevent deviation of the pitch of the vanes and the resulting decrease in oscillation efficiency, as compared with the case of holding only one surface side, which is also advantageous for heat dissipation. Further, since all the vanes are held by both flat plate surfaces of the anode, it is possible to eliminate the need for spacers for holding the vanes.

[Brief description of drawings]

FIG. 1 is a perspective view of a flat plate type magnetron anode according to the present invention.

2 (a) and 2 (b) are side views showing a state in which an oxygen-free copper block which is the basis of the anode of FIG. 1 is grooved.

3 is an exploded perspective view showing a configuration of a flat plate magnetron using the anode of FIG. 1. FIG.

FIG. 4 is a perspective view showing a specific example of a housing used in the flat plate magnetron according to the present invention.

5 is an exploded perspective view showing a state where the anode of FIG. 1 (without a pressure equalizing plate) is incorporated in the housing of FIG.

6 (a) and 6 (b) are side views showing a state in which another groove processing is applied to the oxygen-free copper block which is the basis of the anode of FIG.

FIG. 7 is a partial vertical cross-sectional view of a conventional cylindrical magnetron.

FIG. 8 is a schematic vertical sectional view of a conventional flat plate magnetron.

9 is an external perspective view of the flat plate type magnetron shown in FIG. 8. FIG.

[Explanation of symbols]

1 anode 1a Flat surface 1b Flat surface 2 odd numbered bain 2a end face 3 Even number bain 3a end face 4 Pressure equalizing plate

Claims (6)

(57) [Claims] 1. A flat-plate magnetron anode comprising a plurality of flat-plate vanes standing in a row at the same pitch, wherein an upper part of one flat plate surface of the anode stands in the row.
Of the plurality of flat plate-shaped vanes, the lower part is formed by the end face of the odd-numbered vane and the lower part is formed by the end face of the even-numbered vane, and the upper part of the other flat plate surface of the anode is formed by the end-face of the even-numbered vane. In addition, the lower part is formed of the end faces of the odd-numbered vanes, and the flat plate-shaped conductor is mechanically and electrically bonded to both flat plate surfaces of the anode. 2. The pressure equalizer plate, wherein the conductor is mechanically and electrically joined only to the end faces of the odd-numbered vanes, and the equalizer plate is mechanically and electrically joined only to the end faces of the even-numbered vanes. The flat plate type magnetron anode according to claim 1, comprising a pressure plate. 3. The flat plate mold according to claim 1, wherein the groove processing for forming the vane end surface on both flat plate surfaces of the anode is performed by forging or a combination of a multi-wire saw and brazing. Anode for magnetron. 4. A flat-plate magnetron anode comprising a plurality of flat-plate vanes erected in a row at the same pitch, wherein an upper portion of one flat plate surface of the anode is erected in the row.
Of the plurality of flat plate-shaped vanes, the lower part is formed by the end face of the odd-numbered vane and the lower part is formed by the end face of the even-numbered vane, and the upper part of the other flat plate surface of the anode is formed by the end-face of the even-numbered vane. At the same time, the lower part is a flat plate type magnetron anode formed by the end faces of odd-numbered vanes,
By comprising a housing protrusion is formed with twice the pitch of the Beinpitchi at positions corresponding to the anode vane of the inner wall surface accommodates the anode
The characteristic flat plate magnetron. 5. The flat magnetron according to claim 4, wherein the surface of the protrusion and the groove formed between the protrusions are coated with a conductor. 6. The flat plate mold according to claim 4, wherein the groove processing for forming the vane end surface on both flat plate surfaces of the anode is performed by forging or a combination of a multi-wire saw and brazing. Magnetron.