JP3399703B2 - Anode for flat plate magnetron and method of manufacturing the same - 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 a cross-type magnetic field in which a direct-current magnetic field and a direct-current electric field are present in the electron tube at right angles to each other.
It is one of the field devices and is characterized by high efficiency of about 70%. FIG. 11 is a partial vertical sectional view of a conventional cylindrical magnetron. As shown in FIG. 11, a cylindrical anode 61 is formed with a plurality of vanes 62 protruding radially from the inside toward the central axis. The cylindrical anode 61 and the vanes 62 form a cavity resonator. Are configured.

The cathode 63 is arranged on the central axis of the cylindrical anode 61, and the space surrounded by the cathode 63 and the vane 62 is the working space. A pole piece 64 for uniformly forming a magnetic field in the working space is fixed to both upper and lower ends of the anode 61, and a magnet 66 is attached to the pole piece 64.
Are closely attached and fixed. Further, a large number of heat dissipation plates 67 are arranged between the cylindrical anode 61 and the yoke 65 in order to dissipate the heat generated by the anode loss. Note that the anode loss is that electrons emitted from the cathode are accelerated by the anode voltage,
It is generated by colliding with the anode.

In this structure, the inside of the anode 61 is evacuated and a magnetic field is applied to the working space by the magnet 66,
When a high voltage is applied from the power supply input unit 68 between the cathode 63 and the vane 62, electrons fly out from the cathode 63 toward the vane 62. The ejected electrons perform a cycloidal motion that advances toward the vane 62 while drawing a spiral in the action space by the magnetic field received from the magnet 66. Energy is applied to the cavity resonator from electrons traveling in a spiral in the action space, a high-frequency magnetic field is generated, and the microwave is extracted from the microwave output unit 69 as a microwave.

The main type of magnetron currently used in high-frequency heating equipment such as a microwave oven is a cylindrical type, but there is also a flat type magnetron. 12 is a vertical cross-sectional view of a conventional flat plate magnetron, and FIG. 13 is an external perspective view of the magnetron of FIG. As shown in FIGS. 12 and 13, a plurality of flat plate-shaped vanes 72 are formed on the flat plate-shaped anode 71 inside the housing 81 at the same pitch vertically to the cathode 73 and the sole portion 74. Make up the vessel. The vanes 72 are arranged so that the end faces of the vanes 72 form the side faces of the anode 71.

The cathode 73 is arranged at the lower left end of the anode 71, and the space between the sole portion 74 and the vane 72 is a working space. A pole piece 78 for uniformly forming a magnetic field in the working space is fixed to both side surfaces of the anode 71, and a magnet 76 having a yoke 75 is closely fixed to the pole piece 78. Further, the yoke 75 is provided with a heat dissipation plate 77 for radiating heat generated by anode loss.

In this structure, the inside of the anode 71 is evacuated, and a magnetic field is applied to the working space by the magnet 76,
Power input section 8 between the anode 71, the sole portion 74 and the vane 72
When a voltage is applied from 0, electrons fly out from the cathode 73 toward the vane 72. Electrons that popped out are magnets 7
The magnetic field received from 6 advances to the right in FIG. 12 while performing a cycloidal motion in the action space. Energy is applied to the cavity resonator from these electrons, a high-frequency magnetic field is generated, and the microwave is extracted from the microwave output section 79 as a microwave.

Further, 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.

In the conventional magnetron, modes are separated by a pressure equalizing ring. 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 modes capable of vibrating can be limited to the π mode and the 0 mode (all the anode vanes vibrate in the same phase).

A multi-wire saw is used for processing fine pitch grooves. The multi-wire saw moves a piano wire wrapped between pitched rollers while applying a solution (lapping liquid) in which abrasive particles are dispersed, and performs grooving and cutting. It is mainly used for processing magnetic heads and crystal oscillators. A processing pitch of 0.3 mm and a cutting margin of about 120 μm are possible.

[0011]

The conventional magnetron has an operating voltage of 4 kV and requires a transformer for 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 strength of the applied magnetic field in terms of phase matching. However, when the magnetic field strength is lowered, the oscillation efficiency is significantly reduced. Therefore, it is necessary to deal with it only by making the pitch finer.

However, when the operating voltage of 4 kV is changed to 100 V, the pitch of the anode vanes is 15% of the current one.
However, the processing becomes difficult as compared with the processing of the conventional anode. Further, in the magnetron, its oscillation frequency is determined by the resonance frequency of the cavity of the anode. This resonance frequency is influenced by the shape of the cavity resonator, but its size has a great influence.

In particular, in the flat plate magnetron, since the vanes are parallel to each other and it is difficult to form a gap to increase the capacitance C and the inductance L, it is necessary to increase the groove depth of the cavity resonator. For example, when the operating voltage is 100 V, in order to oscillate at the frequency of 2.45 GHz used for high frequency heating, the groove width of the cavity resonator is 0.1 to 0.25 mm and the groove depth is 30 m.
It will be about m. Therefore, since the height of the vane (groove depth) is extremely large with respect to the thickness of the vane, there is a problem in that the pitch may be displaced due to the deformation of the vane and the efficiency may be reduced. Further, there is a problem that it is difficult to attach a pressure equalizing ring (plate) to the vanes having such a fine pitch. Further, unlike the cylindrical magnetron, the flat plate magnetron has a problem in that the electric field strengths in the respective cavity resonators differ because the anode vanes have terminations.

The present invention provides a flat plate type magnetron anode which can be easily processed and can be easily attached with a pressure equalizing plate, and can prevent a decrease in efficiency due to deformation of a vane and a pitch shift, and a manufacturing method thereof. With the goal. Further, in addition to the above objects, it is another object of the present invention to provide a flat plate type magnetron anode capable of removing the disturbance of the high frequency electric field and improving the oscillation efficiency, and a manufacturing method thereof.

[0015]

Means for Solving the Problems of claims 1 invention, and two conductor groove having twice the pitch of the vanes is formed into a flat plate positive electrode is formed, identical to the pitch of the vane A flat plate type magnetron anode, characterized in that pressure equalizing plates, which are joined to an insulator in which grooves having a pitch are formed, are provided on both flat plate surfaces of the anode.

A second aspect of the present invention is the flat-plate magnetron anode according to the first or second aspect, characterized in that the pressure equalizing plate is fitted in groove portions provided on both flat plate surfaces of the anode.

[0017] The invention of claim 3, in claim 3, is a plate-type magnetron for anode and an end portion of the conductor of the equalizing pressure plate to be bonded to the vane formed in the positive electrode is folded .

[0018] The invention according to claim 4, bonding the steps of providing a groove on both flat surfaces of the flat anode, forming a plurality of vanes by grooving unit to the positive pole, and two conductors and insulators And a step of forming a pressure equalizing plate, forming a groove having the same pitch as the pitch of the vane on one surface of the insulator of the pressure equalizing plate by grooving means, A method for manufacturing a flat plate type magnetron anode, which includes a step of forming grooves having a pitch twice the pitch by the grooving means, and a step of fitting the pressure equalizing plate into the groove portions of the anode.

According to the invention of claim 1, having a two conductor groove is formed to have double the pitch of Beinpitchi been made form <br/> the tabular positive electrode, the Beinpitchi the same pitch Since the pressure equalizing plate formed by joining the insulator with the groove formed is provided on both flat plate surfaces of the anode, the structure of the cavity resonator is simplified and the pressure equalizing plate itself can be easily manufactured.

According to the invention of claim 2 , since the pressure equalizing plates are fitted in the grooves provided on both flat surfaces of the anode, the vanes are fixed by the pressure equalizing plates and the thermal conductivity is also improved by the pressure equalizing plates. To do. Furthermore, the structure is symmetrical because the vanes are connected to both ends of the pressure equalizing plate.

According to the invention of claim 3 , since the end of the conductor of the pressure equalizing plate joined to the vane is bent, the end of the conductor functions as a spring, and when brazing the vane and the pressure equalizing plate. A constant force is generated at the joint.

According to the invention of claim 4, the groove on both flat surfaces of the tabular anode is provided, a plurality of vanes formed by grooving means explicitly poles, equalizing by joining a two conductors and insulators A pressure plate is produced, and grooves having the same pitch as the vane pitch are formed on one surface of the insulator by the grooving means, and grooves having a pitch twice the vane pitch are formed on the one surface of the conductor by the grooving means, and then the even groove is formed. Since the pressure plate is fitted in the groove of the anode, the structure of the cavity resonator is simplified and the pressure equalizing plate itself is easily manufactured. Further, the vane is fixed by the pressure equalizing plate, and the thermal conductivity is also improved by the pressure equalizing plate. Furthermore, the structure is symmetrical because the vanes are connected to both ends of the pressure equalizing plate.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view of an oxygen-free copper block used in a flat plate type magnetron anode according to the present invention. The flat plate oxygen-free copper block 1 shown in FIG. 1 has a length of 10 mm and a width of 60.
mm x height 30 mm, upper part of block 10 mm x 60 m
A block having a length of 20 mm, a width of 60 mm, and a height of 5 mm is joined to the surface of m. Then, the flat plate surface 2 (60 mm × 30 mm) of the copper block 1 has a length of 5 mm × width of 60 mm.
C. A groove 3 having a depth of 2 mm was provided. Furthermore, wire diameter 0.1 is applied to the bottom surface 4 (10 mm × 60 mm) of the copper block 1.
Grooving (167 grooves) was performed with a multi-wire saw using 3 mm and abrasive grain No. GC1000, and as shown in FIG.
Cutting margin 0.15mm, depth 30m at 0.3mm pitch
m of bain 5 was formed. This constituted a cavity resonator, which was used as the anode 10. The reason why the copper block is composed of the two blocks is to make the upper part of the anode also serve as a lid when the flat plate magnetron is packaged, as described later. That is, the protrusion is formed on the anode and the ceramic package is joined.

Next, two pieces of an oxygen-free copper block 7 (one whose surface is silver-plated with an electroless silver plating solution) having a length of 1.5 mm × width of 50 mm × height of 1 mm are formed on an alumina block 6 as shown in FIG. Were joined by brazing as shown in FIG. 4 to produce a pressure equalizing plate 11. In the present embodiment,
A multi-wire saw was used as a grooving means for the pressure equalizing plate.
That is, as shown in FIG. 5, the surface of the alumina block 6 is cut at a pitch of 0.3 mm with a margin of 0.16 mm and a depth of 1 m.
Grooving of m was performed to form a grooved portion 9. Furthermore, a wire diameter of 0.2 mm and abrasive grains of No. GC3000 are used to cut the surface of the copper block 7 at a pitch of 0.6 mm.
Grooves having a depth of m and a depth of 0.4 mm were formed to form grooved portions 8. Since the kerf loss is large with respect to the cut margin, the grooving was performed twice.

Subsequently, the pressure equalizing plate 11 shown in FIG. 5 is fitted and adhered to the groove portion 3 of the anode 10 shown in FIG. 2 as shown in FIG. 6, thereby completing the flat plate type magnetron anode according to the present invention. It was Note that, as shown in FIG. 7, silver which is vertically shifted by a vane pitch and which is plated on the surface of the pressure equalizing plate 11 and copper of the vane 5 act as a silver-copper braze to form the pressure equalizing plate 11 and the vane 5. Joined. Further, the dimensions (cut margin) of the joint between the pressure equalizing plate 11 and the vane 5 are 0.15 mm and 0.12 mm, respectively, for the purpose of absorbing precision deviation during processing.

FIG. 8 is an exploded perspective view showing the structure of a flat plate type magnetron using an anode having no pressure equalizing plate.
FIG. 9 is an exploded perspective view showing the configuration of a flat plate type magnetron using an anode according to the present invention equipped with a pressure equalizing plate. Figure 8
9 and 9, a rod 19 for taking out a microwave output was brazed and joined to the center of one vane of the anode 21 outside the scope of the present invention and the anode 10 according to the present invention. Furthermore, in a vacuum container (10-8 Tor
Each anode 21, 10 was brazed with gold-germanium solder and joined to the housing 12 made of alumina ceramic to which the cathode 13 was die-bonded in step r). Pole pieces 14 for generating a magnetic field necessary for the working space are attached to both side surfaces of the housing 12. The working space is between the sole portion 20 and the vane. A heat sink 17 was provided on a galvanized iron yoke 15, and a ferrite magnet 16 was attached. Finally, the housing 12
The above-mentioned yoke 15 was attached to the housing 12 so as to cover the above, whereby a flat plate type magnetron was completed.

An anode voltage of 100 V was applied to each of the completed flat plate magnetrons from the power supply input section 18, and the anode-sole distance was 0.5 mm, the magnetic field strength was 1360 Gauss, and the emission current was 2.1 A at 2.45 GHz. The oscillation output was measured by a power meter. The oscillation output when using the anode outside the range of the present invention was 15 W, but the oscillation output when using the anode according to the present invention was 18 W.
It was 2W. The oscillation output is improved about 12 times.

Embodiment 2 In the pressure equalizing plate used in the first embodiment, as shown in FIG. 10, the end portion of the conductor 23 of the pressure equalizing plate 22 joined to the vane 5 formed on the anode 10 is bent by 120 degrees. . The pressure equalizing plate 22 manufactured in this manner is used as the anode 1 in the same manner as in the first embodiment.
The flat plate magnetron was assembled using the obtained anode 10 by fitting it into the groove 3 of No. 0. An oscillation output of 2.45 GHz was measured with a power meter under the same conditions as in the first embodiment. As a result, the oscillation output when the anode of this embodiment was used was 196W. That is, the oscillation output when using the anode according to the first embodiment of the present invention is about 13 times that of the oscillation output (15 W) when using the anode outside the scope of the present invention of the first embodiment. (182W)
Improved by about 8%.

Embodiment 3 In this embodiment, an alumina block 31 having a shape adapted to the intensity distribution of a high frequency electric field as shown in FIG. 11 is used. That is, the shape of the alumina block 31 is determined based on the intensity distribution curve of the high frequency electric field calculated by the electromagnetic field simulation. Further, the alumina block 31 is provided with two parallel grooves. Then, as shown in FIG. 12, a multi-wire saw is used as the grooving means, and the alumina block 31 is cut at a pitch of 0.3 mm by 0.16 mm.
Grooving with a depth of 1 mm was performed.

Then, wire diameter 0.2 mm, abrasive grains GC3
Use No. 000 to cut at a pitch of 0.6 mm 0.1
1.5m in height with 2mm and 0.4mm depth grooved
m x 50 mm wide x 1 mm high oxygen-free copper block 32
The two (the surface of which was silver-plated with an electroless silver plating solution) were joined to the two grooves of the alumina block 31 by brazing to manufacture a pressure equalizing plate 33. Therefore, the shape of the pressure equalizing plate 33 manufactured in this way is also adapted to the intensity distribution of the high frequency electric field. Since the kerf loss is large with respect to the cut margin, the grooving was performed twice.

Grooves suitable for the shape of the pressure equalizing plate were formed on both flat surfaces of the flat plate type anode, and after forming the vanes as in the first embodiment, the pressure equalizing plates were fitted and bonded to the grooves. Thus, another flat plate type magnetron anode according to the present invention was completed. The joining method and joining state of the pressure equalizing plate and the anode vane are as described in Embodiment 1 (see FIG. 7).

Then, as shown in FIG. 13, a flat plate magnetron was completed by using the flat plate magnetron anode 40 according to the operation procedure described in the first embodiment. An anode voltage of 100 V is applied from the power input unit 18 to the completed flat plate magnetron, and the distance between the anode and the sole is 0.5.
mm, a magnetic field strength of 1360 Gauss, and an emission current of 2.1 A, an oscillation output of 2.45 GHz was measured by a power meter. The oscillation output when the anode according to the present embodiment is used is 294 W, and the oscillation output when the anode according to the first embodiment is used (182
Compared with W), the oscillation output is improved by about 1.6 times.

Fourth Embodiment In this embodiment, a wet etching process is used as a groove forming means for the pressure equalizing plate. As an etching solution,
A mixture of 100 cc of distilled water and 100 cc of nitric acid and 10 g of silver nitrate was used. When grooving was performed by this process, it was possible to perform processing with the same accuracy (± 0.01 mm) as the multi-wire saw without generating burrs. Further, when the kerf loss is large compared to the cutting allowance, the etching process can perform grooving of the pressure equalizing plate more easily and in a larger amount than the multi-wire saw.

Fifth Embodiment In the present embodiment, forging is used as the grooving means of the pressure equalizing plate. Using a Cr-Mn steel forging die, ± 0.0
It was manufactured with an accuracy of 05 mm. The forging temperature was 800 ° C., and the atmosphere in the furnace was nitrogen. Since a mold is used, the projection has a taper and becomes a tapered shape (tip part 0.12 mm, root part 0.2 mm), but it can be processed with the same accuracy as the multi-wire saw (± 0.01 mm). It was

Embodiment 6 In the present embodiment, punching is used as the groove forming means for the pressure equalizing plate. It is necessary to make the punch smaller than the groove shape of the die by a certain amount of clearance. In the case of precise punching of oxygen-free copper, the practical clearance is 1 to 3% of the plate thickness, so it is 0.01 to 1 mm for a 1 mm thick steel plate.
It becomes 0.03 mm. Therefore, the width of each protrusion of the punch is 0.1 mm with respect to the width of each protrusion of the die of 0.15 mm.
It was set to 1 mm. WC-based cemented carbide was used for the processing tool. A punch having a width of each protrusion of 0.14 mm was used for edge finishing. In the present embodiment, processing with the same accuracy (± 0.01 mm) as the multi-wire saw could be performed.

[0036]

According to the first aspect of the present invention, two conductors each having a groove having a pitch twice that of the vane pitch formed on the flat plate-shaped anode and a groove having the same pitch as the vane pitch are formed. By equipping both flat surfaces of the anode with a pressure equalizing plate that is joined to an insulator, the structure of the cavity resonator is simplified and the pressure equalizing plate itself can be easily manufactured. Further, the processing accuracy can be improved, and the pressure equalizing plate can be easily attached even at a fine pitch, and the oscillation modes can be separated.

According to the invention of claim 2 , the vanes are fixed by the pressure equalizing plates by fitting the pressure equalizing plates into the groove portions provided on both flat plate surfaces of the anode. Can be prevented. This facilitates handling during assembly and transportation.
Further, since the pressure equalizing plate also improves the thermal conductivity, it is possible to prevent deformation of the vane and thermal fluctuation of the magnetic field due to heat. Further, since both ends of the pressure equalizing plate are connected to the vanes, the structure is symmetrical, so that the disturbance of the high frequency electric field is reduced and the output can be stabilized.

According to the third aspect of the invention, by bending the end of the conductor of the pressure equalizing plate that is joined to the vane, the end of the conductor functions as a spring, and when brazing the vane and the pressure equalizing plate. It is possible to apply a constant force to the joint portion, and as a result, it is possible to reduce variations in the joint state between the vanes.

[0039] According to the invention of claim 4, the groove on both flat surfaces of the tabular anode is provided, a plurality of vanes formed by grooving means explicitly poles, equalizing by joining a two conductors and insulators A pressure plate is produced, and grooves having the same pitch as the vane pitch are formed on one surface of the insulator by the grooving means, and grooves having a pitch twice the vane pitch are formed on the one surface of the conductor by the grooving means, and then the even groove is formed. By fitting the pressure plate into the groove of the anode, the structure of the cavity resonator becomes simple and the pressure equalizing plate itself can be easily manufactured. Further, the vane is fixed by the pressure equalizing plate, and the thermal conductivity is also improved by the pressure equalizing plate. Furthermore, the structure is symmetrical because the vanes are connected to both ends of the pressure equalizing plate.

[Brief description of drawings]

FIG. 1 is a perspective view of an oxygen-free copper block used in a flat plate type magnetron anode of the present invention.

2 is a perspective view of a flat plate type magnetron anode including a cavity resonator formed by forming a vane on the oxygen-free copper block of FIG. 1. FIG.

FIG. 3 is a perspective view of an alumina block used for a pressure equalizing plate.

FIG. 4 is a perspective view showing a state in which an oxygen-free copper block is joined to the alumina block of FIG.

5 is a perspective view of a pressure equalizing plate showing a state in which grooves are provided in the joined blocks of FIG.

6 is a perspective view of the flat plate type magnetron anode of the present invention showing a state in which the pressure equalizing plate of FIG. 5 is fitted in the groove of the anode of FIG. 2.

FIG. 7 is a partial enlarged view showing a joint portion between the pressure equalizing plate and the anode in FIG.

FIG. 8 is an exploded perspective view showing a configuration of a flat plate magnetron when an anode outside the scope of the present invention is used.

FIG. 9 is an exploded perspective view showing a configuration of a flat plate type magnetron when the anode according to the present invention is used.

10 is a partial cross-sectional view of the flat plate type magnetron anode of the present invention showing a state where a pressure equalizing plate of another embodiment is fitted to the anode of FIG.

FIG. 11 is a perspective view of another alumina block used for the pressure equalizing plate.

FIG. 12 is a perspective view of a pressure equalizing plate configured by joining a grooved alumina block and an oxygen-free copper block.

FIG. 13 is an exploded perspective view showing a configuration of a flat plate type magnetron when another anode according to the present invention is used.

FIG. 14 is a partial vertical cross-sectional view of a conventional cylindrical magnetron.

FIG. 15 is a vertical cross-sectional view of a conventional flat plate magnetron.

16 is a perspective view of the flat plate type magnetron of FIG. 15. FIG.

[Explanation of symbols]

1 Flat plate oxygen-free copper block 2 Flat surface 3 groove 4 bottom 5 Bain 6 Alumina block 7 oxygen-free copper block Grooving part of 8 oxygen-free copper block 9 Groove of alumina block 10 Flat anode 11 Pressure equalizing plate

─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP-A-52-48462 (JP, A) JP-A-49-16372 (JP, A) JP-A-49-69067 (JP, A) JP-A-5- 283878 (JP, A) JP-A-58-46546 (JP, A) JP-A-48-90464 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01J 23 / 18-23 /twenty two

Claims (4)

(57) [Claims] And two conductor groove is formed with a 1. A 2 times the pitch of the pitch of the flat positive pole formed Bain,
An anode for a flat plate magnetron, characterized in that pressure equalizing plates, which are joined to an insulator having grooves having the same pitch as the vane pitch, are provided on both flat plate surfaces of the anode. 2. The flat plate type magnetron anode according to claim 1, wherein the pressure equalizing plate is fitted in grooves formed on both flat plate surfaces of the anode. Wherein the plate type magnetron anode for according to claim 2, wherein the ends of the conductors of the equalizing pressure plate to be bonded to the vane formed explicitly electrode is bent. A step wherein providing the groove section on both flat surfaces of the flat anode, forming a plurality of vanes by grooving unit to the positive pole, the two conductors and equalizing the pressure plate by bonding insulator A step of producing, a step of forming grooves having the same pitch as the pitch of the vanes on one surface of the insulator of the pressure equalizing plate by the grooving means, and a double pitch of the vanes on one surface of the conductor of the pressure equalizing plate. And a step of fitting the pressure equalizing plate into the groove of the anode, the method for producing a flat plate magnetron anode.