JP3001097U - High frequency oscillator - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a high-frequency oscillator for preventing leakage of harmonic components generated from a magnetron for a microwave oven. A pole piece 134 of an anode cylinder 131 having a plurality of anode vanes 133 on the inner peripheral surface thereof projecting toward the cathode filament 132 and forming a cavity resonance is provided with a choke 160 for preventing leakage of a specific harmonic. .

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a magnetron, and more particularly to a high frequency oscillator that prevents harmonic components generated from a magnetron for a microwave oven from leaking to the outside.

[0002]

[Prior art]

 In general, magnetrons are widely used in microwave ovens as microwave generation means.

By the way, the harmonic components leaking from the magnetron of the microwave oven cause the radio communication interference of televisions and radios. There are various factors such as defects in the sealing part of the microwave oven door and defects in the sealing of the turntable motor shaft that can cause the harmonics of the microwave to leak. It was an important issue because there was a danger of leaking to the. Therefore, various techniques have been proposed to shield the harmonic components leaking from the magnetron.

A typical example of the conventional technique is described in Korean Patent Application Publication No. 384 of 1993 (Korean Patent Application No. 3669 of 1990).

In this conventional example, as shown in FIG. 2, a plurality of anode vanes 2 that project toward the cathode filament 10 to form a cavity resonator are provided inside the anode cylinder 1. First and second magnetic pole pieces 5 and 6 for focusing a magnetic field are arranged to face each other at both open ends of the cylindrical body 1. Further, a first cylinder 20 for harmonic chokes and a second cylinder 21 for harmonic chokes are airtightly fixed to one end of the first metal tube 18 via an insulating tube 19 made of ceramic.

The flange portion 18 a of the first metal tube 18 is hermetically sealed at one open end of the anode cylinder 1 so as to cover the first magnetic pole piece 5 in an airtight manner. Further, the second and third metal pipes 33 and 34 are fixed inside the first metal pipe 18.

The cylindrical portion 33a of the second metal tube 33 has a length L1 corresponding to 1/4 of a specific harmonic wavelength λ1, the flange portion 33b extends outward, and A through hole 33c through which the antenna 24 as a conductor for deriving microwaves is inserted and a slot 33d (FIG. 3) having a length of 1/2 of a specific harmonic wavelength λ1 are formed in the ceiling portion.

Further, the cylindrical portion 34a of the third metal tube 34 has a length L2 corresponding to ¼ of another specific harmonic wavelength λ1, and the flange portion 34b is directed outward at the lower portion thereof. And a through hole 34c through which the antenna 24 is inserted is formed in the ceiling. Here, the space 40 defined by the cylindrical portion of the first metal pipe 18, the cylindrical portion 33a of the second metal pipe 33, and the flange portion 33b acts as a first choke, and the cylindrical portion 33a of the second metal pipe 33 is used. The space 41 defined by the cylindrical portion 34a and the flange portion 34b of the third metal tube 34 acts as a second choke.

The first choke 40 is set to have a length L1 so as to attenuate lower harmonics than the second choke 41. Further, the first cylinder 20 is connected so that the height thereof is L3 in order to shield the leakage of harmonics.

Further, a through hole 5 a through which the antenna 24 is inserted is formed on one side of the first magnetic pole piece 5.

Further, a pair of end pads 12 and 13 are fixed to both ends of the cathode filament 10 wound in a coil shape. At the connection point between the inside of the end pad 12 and the upper end of the cathode filament 10, one end of the cathode terminal lead conductor 7 penetrating the lower end pad 13 is fixed. Another cathode terminal lead conductor 8 is fixed to one side of the lower end pad 13.

These cathode terminal lead-out conductors 7 and 8 are fixed to terminal plates 14 and 15 which penetrate the stem insulator 9 and are hermetically welded to the outer surface. Between the second magnetic pole piece 6 and the stem insulator 9, a fourth metal tube 3 forming a part of the vacuum container is airtightly fixed by soldering or the like.

In FIG. 2, reference numeral 11 is a choke coil that is connected to a feedthrough capacitor (not shown) to form a filter, and reference numerals 2a to 2d are equalizing rings. Further, an annular permanent magnet (not shown) having a hole in the center is provided outside the first and second magnetic pole pieces 5 and 6 of the magnetron configured as described above. That is, the first and fourth metal tubes 18 and 3 are installed in a state where they are inserted into the central holes of the permanent magnets.

When a predetermined voltage is input to the magnetron configured as described above, the cathode filament 10 emits heat to generate a thermoelectron group.

The thermoelectron group is directed toward the anode vane 2, but since a magnetic flux is formed by the permanent magnet between the cathode filament 10 and the anode vane 2, the thermoelectron group makes a rotational motion. Like

When the thermoelectron group makes a rotational motion as described above, an LC resonance circuit is formed in the anode vane 2 to oscillate.

A high frequency of, for example, 2450 MHz is generated. This high frequency wave is guided to the upper part through the antenna 24 and is output to the waveguide (not shown) of the microwave oven. At this time, leakage of higher harmonic waves is blocked by the first choke 40 of the second metal tube 33, the second choke 41 of the third metal tube 34, and the first cylinder 20 for higher harmonic chokes.

[0018]

As described above, in the conventional magnetron, while the microwave including the fundamental wave of 2450 MHz and a specific harmonic component corresponding to an integral multiple of the fundamental wave is being output, the antenna 24 of the magnetron is used. Since the first and second chokes 40 and 41 and the first harmonic choke cylinder 20 are formed in order to shield the higher harmonic components emitted to the outside along the above, the manufacturing process of the magnetron is complicated. There was a problem that

Therefore, the present invention has been made to solve the above-mentioned problems, and a choke is provided on the first pole piece toward the anode vane to prevent the leakage of a specific harmonic. It is an object of the present invention to provide a high-frequency oscillator having the structure.

[0020]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, a high-frequency oscillator according to the present invention provides a first pole piece of an anode cylinder having a plurality of anode vanes on its inner peripheral surface which project in the cathode filament direction and form cavity resonance. It is characterized by the provision of a choke to prevent the leakage of water.

[0021]

【Example】

 An embodiment of a high frequency oscillator according to the present invention will be described in detail below with reference to the accompanying drawings.

In FIG. 1, the cylindrical anode cylinder 131 has a plurality of anode vanes 133 that protrude toward the cathode filament 132 supported by the end pads 137 and 138 to form a cavity resonance on the inner peripheral surface. Funnel-shaped first and second magnetic pole pieces 134 and 135 for focusing a magnetic field are provided at both open ends of the anode cylinder 131 so as to face each other. An insulating pipe 157 made of ceramic is sealed in the metal exhaust pipe 156, and a cylindrical metal pipe 158 is sealed in the insulating pipe 157. The flange portion 158a of the metal tube 158 is sealed at the open end of the anode cylinder 131 so as to cover the first magnetic pole piece 134. An antenna 159 as a microwave lead-out conductor extends from any one of the plurality of anode vanes 133, and the other end of the antenna 159 is connected to an exhaust pipe 156. A metal cap-shaped microwave output terminal 150 is fixed to the outside of the exhaust pipe 156.

At least one choke 160 is attached to the first pole piece 134 toward the anode vane 133. That is, at least one rod-shaped choke 160 having a length 1 corresponding to 1/4 of the specific harmonic wavelength λ is provided on the lower surface of the first magnetic pole piece 134 facing the second magnetic pole piece 135 toward the anode vane 133. It is attached so that certain harmonics are prevented from leaking out of the magnetron.

The open end of the ceramic cup-shaped stem insulator 143, through which the pair of cathode leads 141 and 142 are airtight, is sealed by the cylindrical metal tube 144, and the flange portion of the metal tube 144 is sealed. 144a is sealed at the open end of the anode cylinder 131 so as to cover the second magnetic pole piece 135.

The stem insulator 143 and the pair of cathode leads 141, 142 are connected to terminal pieces 145, 146 provided outside the stem insulator 143. An annular groove 143a having a width W1 mm or more and a depth h is formed between each one end of the pair of terminal pieces 145, 146 and the outer diameter of the stem insulator 143, and the terminal piece 145 or 146 and the metal pipe 144 are formed. Make sure to keep the insulation distance between and 15.5mm (spreading distance is 17.5mm or more).

Further, annular permanent magnets (not shown) having a hole in the center are provided outside the first and second magnetic pole pieces 134 and 135 of the magnetron, respectively, and the metal tube 158 and the metal tube 158 are provided in the holes. 144 are inserted respectively.

When a predetermined voltage is input to the magnetron configured as described above, the cathode filament 132 emits heat to generate a thermoelectron group.

The thermoelectron group is directed toward the anode vane 133, but since a magnetic flux is formed between the cathode filament 132 and the anode vane 133 by the permanent magnet, the thermoelectron group makes a rotational motion. Like As described above, when the thermoelectron group makes a rotational movement, the LC resonance circuit is formed in the anode vane 133 and oscillates.

That is, a high frequency of 2450 MHz is generated. This high frequency wave is guided to the upper part through the antenna 159 and is output to the waveguide (not shown) of the microwave oven. At this time, the choke 160 set to a length 1 which is 1/4 of the wavelength of the specific harmonic wave attenuates the specific harmonic component corresponding to an integral multiple of the fundamental frequency of 2450 MHz and blocks the leakage to the outside.

[0030]

[Effect of device]

 As described above, according to the high-frequency oscillator according to the present invention, it is possible to prevent the leakage of high-harmonic components to the outside by a simple structure and prevent electromagnetic interference to various electronic devices in the vicinity.

Obviously, various modifications according to the present invention can be implemented. In particular, the present proposal is not limited to the magnetron structure described as an example above, and the choke setting position is not limited to the first pole piece, and the harmonic component can be effectively blocked. It may be set to the position. That is, for example, the choke can be attached to the inner surface of the second magnetic pole piece 135 or any of the first and second magnetic pole pieces 134 and 135 or the inside of the anode cylinder 131.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of a magnetron according to the present invention.

FIG. 2 is a schematic vertical sectional view showing a structure of a conventional magnetron.

FIG. 3 is a plan view showing a configuration of a first metal tube in FIG.

[Explanation of symbols]

 131 Anode cylinder 132 Cathode filament 133 Anode vane 134 First magnetic pole piece 135 Second magnetic pole piece 137, 138 End pad 150 Microwave output terminal 156 Exhaust pipe 157 Insulation pipe 158 Metal pipe 158a Flange portion 159 Antenna

Claims (7)

[Scope of utility model registration request] 1. A choke for preventing leakage of a specific harmonic is provided on a pole piece of an anode cylinder having an inner peripheral surface having a plurality of anode vanes protruding in the cathode filament direction to form a cavity resonance. High frequency oscillator. 2. The high frequency oscillator according to claim 1, wherein at least one choke is provided. 3. The high frequency oscillator according to claim 1, wherein the choke is provided on an inner surface of the first pole piece. 4. The high-frequency oscillator according to claim 3, wherein the choke is provided toward the anode vane. 5. The choke has a specific harmonic wavelength of 1 /
4. A rod-shaped body having a length of 4. 4.
Alternatively, the high frequency oscillation device according to item 2. 6. The high-frequency oscillator according to claim 1, wherein an antenna of a conductor for deriving a microwave is passed through the first pole piece. 7. A cathode filament, an anode cylinder having a plurality of anode vanes projecting toward the cathode filament and forming a cavity resonator on an inner peripheral surface thereof, and a first cylinder attached to both ends of the anode cylinder. First and second magnetic pole pieces, an antenna for deriving a microwave from the cavity resonator, a permanent magnet that forms a magnetic flux in the cavity resonator, and at least one of the first and second magnetic pole pieces High-frequency oscillator comprising at least one rod-shaped choke mounted on the substrate and formed to have a constant length for a specific harmonic.