JP3333421B2 - Flat 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-type magnetron used for a high-frequency heating device such as a microwave oven.
In particular, the present invention relates to a general-purpose flat-plate type magnetron capable of efficiently extracting a microwave having a desired output and frequency.

[0002]

2. Description of the Related Art A magnetron is one of crossed field devices in which a DC magnetic field and a DC electric field are perpendicular to each other in a working space in an electron tube. The oscillation mode includes an A-type oscillation and a B-type oscillation. There is.

[0003] The A-type oscillation depends only on the magnetic field strength and is caused by the periodic rotational movement of electrons by the magnetic field. Also,
Unlike the B-type oscillation mode described later, the oscillation wavelength is not so affected by the cavity resonator which is an external circuit.
The oscillation wavelength is determined only by the magnetic field, and the following relationship is established. λ = α / H where λ is the oscillation wavelength, H is the magnetic field strength, and α is 2πmc / e
Becomes Here, since m indicates the mass of the electron and e indicates the charge of the electron, the constant α is theoretically 1065
Although it is 0, it is experimentally a value of 10000 to 13000. In the A-type oscillation, there are a trajectory of electrons that take away energy from the AC electric field and a trajectory of electrons that give energy to the AC electric field, and it is necessary to remove the former from the orbit.

Next, B-type oscillation will be described with reference to FIG. FIG. 2 is a diagram showing a configuration of a conventional cylindrical magnetron. As shown in the figure, a plurality of vanes 22 are radially formed on the cylindrical anode 21 toward the center, and this constitutes a cavity resonator. The cathode 23 is arranged on the central axis of the cylindrical anode, and the cathode 23 and the vane 22 are arranged.
Is the working space.

At both upper and lower ends of the anode 21, pole pieces 24 for forming a uniform magnetic field in the working space are attached in close contact with a magnet 26 having a yoke 25,
A radiating plate 27 for dissipating heat generated due to anode loss is disposed between the anode 21 and the yoke 25. The anode loss occurs when electrons emitted from the cathode 23 and accelerated by the anode voltage collide with the anode 21.

An electrode (end hat) 30 exists perpendicular to the direction of the magnetic field across the working space, and electrons are confined in the working space by applying a negative potential to the end hat 30. .

In this configuration, the inside of the anode 21 is evacuated, a magnetic field is applied to the working space by the magnet 26, and the cathode 23-
When a high voltage is applied between the two, electrons jump from the cathode 23 toward the vane 22. Then, the jumped-out electrons perform a cycloidal motion that proceeds toward the vane 22 while drawing a spiral in the action space by the magnetic field received from the magnet 26. As a result, these electrons impart energy to the cavity resonator, generating a high-frequency electric field, which is extracted from the microwave output unit 29 as a microwave.

At present, cylindrical magnetrons are mainly used for high-frequency heating devices such as microwave ovens.
There is also a flat magnetron. 3 and 4 are a cross-sectional view and a perspective view, respectively, of the flat-type magnetron.
The flat anode 41 shown in FIG.
Are formed perpendicularly to the cathode 43 and the sole portion 51, and this constitutes a cavity resonator. The cathode 43 is
It is arranged at the lower left end of the anode 41, and the space between the sole 51 and the vane 42 is the working space. On both sides of the anode 41, pole pieces for forming a uniform magnetic field in the working space are attached in close contact with the magnet of the yoke, and the yoke is provided for releasing heat generated by anode loss. A radiator plate 47 is provided.

In this configuration, the inside of the anode 41 is evacuated, and a magnetic field is applied to the working space by the magnet 46.
When a voltage is applied between the anode 41, the sole 51, and the vane 42 from a power input portion, electrons jump from the cathode 43 toward the vane 42.

[0010] Then, the electrons that have jumped out of the magnet 4
3 moves to the right in FIG. 3 while performing cycloidal motion in the working space similarly to the cylindrical magnetron by the magnetic field received from the electron, and energy is applied to the cavity from these electrons, and a high-frequency electric field is generated. It is extracted from the microwave output unit 49.

In the case of a magnetron using a divided anode, oscillations in various modes can occur depending on the number of divisions. The mode mainly used in the B-type oscillation is the phase between adjacent resonators. The transition is equal to π radian and is called the π mode which has the strongest interaction.

However, in the oscillation of the magnetron, this π
If the oscillation frequency of one mode is close to the oscillation frequency of another mode,
A mode-jumping from π mode to another mode occurs in response to slight changes in operating conditions.
As a result, the oscillation frequency and the output change abruptly, so that it is necessary to make the coupling between the resonators denser and separate the resonance frequencies of the respective modes as much as possible.

In a conventional magnetron, such modes are separated by using an equalizing ring in which every other anode and vane are connected by a conductor. In other words, the potential equalizing ring forces the potential of every other anode to oscillate in the same phase, so that the oscillating modes are π mode and 0 mode (all anodes and vanes oscillate in the same phase). Can be limited to

[0014]

As described above, in the conventional magnetron, a constant magnetic field is applied to the working space by the magnet bonded to the yoke, so that a microwave having a constant frequency and a constant output is generated. Was to get. Therefore, the output and frequency to be obtained from the magnetron cannot be changed according to the purpose of use.

In particular, this magnetron has extremely useful characteristics that it has a very high oscillation efficiency and can obtain a large output at a low cost. Therefore, application to not only a microwave oven but also a wide range of technical fields is desired. Therefore, it has been an important issue how to realize a versatile magnetron that can be widely applied to various fields such as communication, radar, and electronic equipment.

Therefore, the present invention solves the above problems,
It is an object of the present invention to provide a highly versatile plate magnetron capable of efficiently extracting microwaves having a desired output and frequency.

[0017]

According to a first aspect of the present invention, a cathode for generating electrons, an anode having a plurality of vanes provided at the same pitch, and a cathode sandwiched between the cathode and the anode are provided. In a flat-type magnetron having a magnet portion that forms a uniform magnetic field in the working space, and electrodes disposed on opposite sides of the working space and perpendicular to the direction of the uniform magnetic field, the magnet portion is located in the working space. The strength of the magnetic field to be formed is varied.

According to a second aspect of the present invention, there is provided a pole piece in which the magnet portion is disposed on both sides of the working space so as to face each other, and a magnet which is in close contact with the pole piece and the yoke and is magnetically coupled. Wherein the magnet is movable.

The third invention is characterized in that the length of the pole piece can be changed.

A fourth aspect of the present invention is characterized in that the length of the yoke can be changed.

According to a fifth aspect of the present invention, there is provided a flat-type magnetron wherein a positive and a negative potential can be selectively applied to the electrode.

For this reason, the output can be made variable in accordance with the change in the potential of the electrode, the frequency can be made variable in accordance with the change in the distance between the magnets, and oscillation of the oscillation can be achieved by applying a positive potential to the electrode. Interfering electrons can be excluded from the working space.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a flat-type magnetron according to the present invention. As shown in FIG.
The flat magnetron includes an anode 11, a vane 12, a cathode 13, a pole piece 14, a yoke 15, a magnet 16, and an end hat 20. The space between the anode 11 and the cathode 13 arranged in the vertical direction is the working space 18. Electrodes for giving positive and negative potentials, that is, end hats 20 are disposed opposite to each other at both ends in the horizontal direction of the working space 18, and a magnetic field required for the working space 18 is provided on the side of both end hats 20. The pole pieces 14 to be generated are arranged to face each other. The magnet 16 is arranged further to the side of the hole piece 14 . The magnet 16 has a yoke 15, which is in contact with the anode 11. What forms the magnetic field in the working space 18 is the magnet 16, the pole piece 14, and the yoke 15, which are magnetically coupled, and collectively form a magnet portion.

Here, the magnet 16 is attached to the side surface of the housing and is made of a ferrite magnet. The yoke 14
Since it also serves as a radiator plate for dissipating heat generated by anode loss, it is made of zinc-plated iron. Also,
In order to make the gap (distance between the magnet parts) of the magnet part which influences the magnetic field strength of the working space 18 movable, the flat magnetron has the pole piece 14 and the yoke 15 formed in a bellows shape to reduce the distance between the magnet parts. It is variable within a range of 20 mm. Magnet 1
6 can be moved accordingly. In addition,
The anode 11 was prepared by using the method for manufacturing a flat magnetron anode disclosed in Japanese Patent Application No. 7-181367.

Next, an outline of the operation of the flat type magnetron will be described. First, when the bellows of the pole piece 14 and the yoke 15 are operated to set a desired distance between the magnet parts, a desired magnetic field is formed on the working space 18. Here, when a voltage is applied to the end hat 20, the cathode 13
Electrons jump out of the device.

The ejected electrons travel under the influence of the magnetic field in the action space 18 while performing cycloidal motion, and energy is applied to the cavity from the electrons to generate a high-frequency electric field. Therefore, a microwave having a frequency and an output corresponding to the distance between the magnets, that is, the operation amounts of the pole piece 14 and the yoke 15 is extracted.

The flat-type magnetron shown in FIG. 1 allows the positive and negative potentials to be selectively applied to the end hat 20, makes the magnet 16 movable, and makes the yoke length and the pole piece length variable. , And a desired output and frequency can be obtained. That is, in the flat-type magnetron, a positive potential is applied to the end hat 20 to remove electrons that hinder oscillation from the working space, and the output is manipulated by changing the potential.

The magnet 16 is made movable and the yoke length and the pole piece length are made variable using the bellows-like pole piece 14 and yoke 15, thereby changing the distance between the magnet parts and controlling the frequency. I do.

Specifically, the anode voltage is set to 100 V,
The distance between the soles is 0.5 mm and the magnetic field strength is 1360 Ga
uss (distance between magnets 30 mm), end-hat potential-
When 10V and emission current are 2.1A,
An oscillation output of 160 W (2.5 GHz) can be obtained.

Then, the magnetic field strength is set to 1090 Gauss.
When it is changed to s, an oscillation output of 3 W to 7 W is obtained at a frequency of 3.1 GHz to 5.1 GHz. When a potential of +10 V is applied to the end hat section 20 , 3.1 GHz
At a frequency of up to 5.1 GHz, an oscillation output of 10 W to 20 W is obtained, which is three times that of the former.

[0031]

As described above in detail, according to the first to fourth aspects of the present invention, the magnet portion is configured to be capable of changing the magnetic field intensity formed in the working space. The oscillation frequency can be varied. In particular, magnets,
By varying the pole piece length or the yoke length, the magnetic field strength can be varied according to the change in the distance between the magnet parts, and the frequency can be varied.

According to the fifth aspect of the present invention, since the positive and negative potentials are applied to the electrodes, by applying a positive potential to the electrodes, the electrons which hinder the oscillation can be excluded from the working space. Becomes possible.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a flat-type magnetron according to the present invention.

FIG. 2 is a configuration diagram of a conventional cylindrical magnetron.

FIG. 3 is a cross-sectional view of a conventional flat-type magnetron.

FIG. 4 is a perspective view of a conventional flat-type magnetron.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Anode 12 Bain 13 Cathode 14 Pole piece 15 Yoke 16 Magnet 20 End hat

Continuation of the front page (56) References JP-A-8-162030 (JP, A) JP-A-8-78153 (JP, A) JP-A 54-129961 (JP, U) JP-A 52-32263 (JP U.S. Pat. No. 5,162,030 (JP, U) Patent 122945 (JP, C2) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01J 23/10 H01J 23/05

Claims (4)

(57) [Claims] 1. A cathode for generating electrons, an anode having a plurality of vanes provided at the same pitch, a magnet unit for forming a uniform magnetic field in a working space between the cathode and the anode, and both sides of the working space. In the flat-type magnetron having electrodes disposed so as to be opposed to each other and perpendicular to the direction of the uniform magnetic field, the magnet units are disposed to be opposed to both sides of the working space.
Pole piece and the pole piece and yoke
Moving the magnet
A flat-type magnetron , wherein the intensity of a magnetic field formed in the working space is varied. 2. A cathode for generating electrons and a plurality of vanes.
An anode provided at the same pitch, and sandwiched between the cathode and the anode
A magnet part for forming a uniform magnetic field in a separated working space;
Perpendicular to the direction of the uniform magnetic field on opposite sides of the space
In the flat-type magnetron having the electrodes disposed, the magnet units are disposed on both sides of the working space so as to face each other.
Pole piece and the pole piece and yoke
And a magnetically coupled magnet.
The magnetic field strength formed in the working space is
Flat type magnetron characterized by variable degree . 3. A cathode for generating electrons and a plurality of vanes.
An anode provided at the same pitch, and sandwiched between the cathode and the anode
A magnet part for forming a uniform magnetic field in a separated working space;
Perpendicular to the direction of the uniform magnetic field on opposite sides of the space
In the flat-type magnetron having the electrodes disposed, the magnet units are disposed on both sides of the working space so as to face each other.
Pole piece and the pole piece and yoke
And a magnet that is magnetically coupled to the yoke.
The strength of the magnetic field formed in the working space
A flat plate type magnetron characterized by changing. 4. A cathode for generating electrons and a plurality of vanes.
An anode provided at the same pitch, and sandwiched between the cathode and the anode
A magnet part for forming a uniform magnetic field in a separated working space;
Perpendicular to the direction of the uniform magnetic field on opposite sides of the space
And a plate-type magnetron having an electrode disposed thereon, and a positive and a negative potential can be selectively applied to the electrode.
A flat-type magnetron characterized by the following .