KR19980056319U - Magnetron cathode structure - Google Patents

Abstract

The present invention relates to the structure of the cathode portion of the magnetron, the filament 17 for emitting hot electrons, the filament electrodes (23, 25) for supporting the filament 17, and the filament electrodes (23, 25) through the External connection terminals 29 and 31 for supplying power to the filament 17, choke coils 30 and 32 connected to the external connection terminals 29 and 31 to remove line noise transmitted through the power line. And the ferrite 36 wound around the choke coils 30 and 32 to absorb low frequency noise transmitted through the power line, and improve the shapes of the choke coils 30 and 32 and the ferrite 36 to form a cathode. It can effectively eliminate the line noise leaking to the outside through the part.

Description

Magnetron cathode structure

The present invention relates to a magnetron used in a microwave heating apparatus such as a microwave oven, and more particularly, to a cathode portion structure of a magnetron for removing line noise leaking through a power line.

In general, microwave magnetrons generate microwave energy in the 2450MHz band at the anode cylinder and generate harmonic components having frequencies corresponding to integer multiples of the fundamental waves.

At this time, the energy of the fundamental wave and harmonic components generated in the anode cylinder is radiated to the output of the magnetron and transferred to the cavity of the microwave oven through the waveguide. It is organically dispersed and propagates outside through the lead wire.

As described above, in addition to causing radio communication disturbance of energy transmitted to the outside, it may also harm the human body. In some regions, the limit of leakage is regulated by law.

Currently, in the case of the microwave magnetron, harmonics ranging from the second harmonic (4900 MHz) to the seventh harmonic (7350 MHz) and frequencies from 30 KHz to 2 GHz are regulated or recommended standards, but the fundamental wave (2450 MHz) and its fundamental wave are Most of harmonic components are leaked to the output part of the magnetron, and some of them have 3 ~ 4% of the microwave energy leaked to the cathode part, so it is necessary to reduce the fundamental and harmonics of the fundamental wave and noise of 15KHz ~ 2GHz band. Do.

Accordingly, in the conventional magnetron structure of the magnetron for suppressing microwave energy leaking through the cathode portion, as shown in FIG. 1, the anode shield in which the lower shield cup 1 surrounding the funnel-shaped pole piece is not shown. Molybdenum lead wires 3 and 4, which are cathode support members for supporting the filament 2, are welded and hermetically contacted to one end surface of the lower shield cup 1, and have upper and lower shields. It is welded to the hats 5 and 6.

The lead wires 3 and 4 are electrically connected to external connection terminals 8 and 9 which are connected to power terminals, not shown, through through holes formed in the insulating ceramic 7, and the external connection terminals. One end of the choke coils 10 and 11 is electrically connected to (8, 9).

In addition, the other ends of the choke coils 10 and 11 are connected to a capacitor 12 disposed in the side wall portion of the filter box, and within the choke coils 10 and 11, a fundamental wave of 2450 MHz is applied. The negative electrode structure was constructed by inserting and fixing the ferrites 10a and 11a absorbing the noise along the longitudinal direction of the choke coils 10 and 11.

By the way, in the negative electrode structure of the conventional magnetron configured as described above, the microwave energy propagated to the outside through the lead wires 3 and 4 is LC based on the L value of the choke coils 10 and 11 and the C value of the capacitor 12. Leakage can be suppressed by the resonant circuit and the ferrites 10a and 11a, but the limit of the desired frequency band is limited due to the structure and price of the L value of the choke coils 10 and 11 and the C value of the capacitor 12. There was a problem that was impossible.

In addition, since a separate capacitor for constituting the LC resonant circuit must be disposed, not only the configuration is complicated but also the manufacturing cost increases.

In addition, since one end of the lead wires 3, 4 is connected to the filament 2, and the other end of the lead wires 3, 4 is connected to the external connection terminals 8, 9, Harmonics are easily propagated to the outside through the cathode to generate line noise, which is supplied to the magnetron through lead wires 3 and 4 and external connection terminals 8 and 9 connected to the filament 2. Flowing out to the power supply line, this power line is connected to the power supply of the microwave oven has a problem that causes an external device malfunction.

Therefore, the present invention has been made to solve the above problems, and by improving the shape of the choke coil and ferrite to effectively remove the line noise leaking to the outside through the cathode portion to prevent the malfunction of the device and at the same time structure The purpose is to provide a negative electrode structure of the magnetron that can be simple to reduce the cost.

In order to achieve the above object, the magnetron structure of the magnetron according to the present invention includes a filament for emitting hot electrons, a filament electrode for supporting the filament, an external connection terminal for supplying power to the filament through the filament electrode, and a power source And a choke coil connected to the external connection terminal to remove line noise transmitted through the line, and a ferrite wound around the choke coil to absorb low frequency noise transmitted through the power line.

1 is a longitudinal cross-sectional view of a cathode structure of a magnetron according to the related art;

2 is a longitudinal sectional view of a magnetron according to an embodiment of the present invention;

3 is a configuration diagram of a choke coil according to a second embodiment of the present invention,

4 is a configuration diagram of a choke coil according to a third embodiment of the present invention,

5 is a configuration diagram of a choke coil according to a fourth embodiment of the present invention,

6 is a configuration diagram of a choke coil according to a fifth embodiment of the present invention,

7 is a configuration diagram of a choke coil according to a sixth embodiment of the present invention;

8 is an equivalent circuit diagram of an inductor applied to the present invention.

* Description of the symbols for the main parts of the drawings *

12: working space 13: anode cylinder

15: vane 17: filament

20: upper shield hat 21: lower shield hat

23: first filament electrode 25: second filament electrode

27: insulated ceramic 29, 31: external connection terminal

30, 32: choke coil 33, 35: upper and lower pole pieces

36: ferrite 37, 39: upper and lower shield cup

41, 43: magnet 45: antenna ceramic

47: exhaust pipe 49: antenna

51 antenna cap 53, 55 upper and lower yoke

57: cooling fin

Hereinafter, with reference to the accompanying drawings an embodiment of the present invention will be described in detail.

As shown in Fig. 2, inside the anode cylinder 13 formed in a cylindrical shape by a copper pipe or the like, a plurality of shafts 10 to 12 vanes 15 are formed to form a plurality of resonant cavities to induce high frequency components. It is arrange | positioned at equal intervals toward a direction, and these anode cylinders 13 and the vane 15 comprise an anode part.

In addition, the inner and outer straps 15a and 15b are connected to each other by the vanes 15 so as to obtain a constant resonance frequency by varying capacitances in the upper and lower portions near the tip end side of the vanes 15, respectively. A working space 12 is formed between the front end portions of the plurality of vanes 15 and the filaments 17 near the central axis of the anode cylinder 13, and the tungsten (Tungsten) is formed to generate high heat in the working space 12. A filament heater 17 (hereinafter referred to as a filament) wound in a spiral shape by mixing and sintering W) and thorium oxide (ThO ₂ ) is disposed coaxially with the anode body 13.

Upper and lower shield hats 20 and 21 are fixed to both ends of the filament 17 so as to prevent radiation of hot electrons, which do not contribute to oscillation, from being radiated in the central axis direction. In the center portion, a first filament electrode 23, which is a central support made of molybdenum, is welded to the lower end of the upper shield hat 20 through a through hole 22 formed in the center portion, and the bottom of the lower shield hat 21 is fixed. A molybdenum second filament electrode 25 is welded to the surface.

The first filament electrode 23 supports the upper shield hat 20 while passing through the central axis of the filament 17, and the first and second filament electrodes 23 and 25 support and fix the cathode of the magnetron. Electrically connected to the first and second external connection terminals 29 and 31 connected to the power supply terminals 30b and 32b through the through holes formed in the 27, the current is supplied to the filament 17.

One end of the first and second choke coils 30 and 32 is electrically connected to the first and second external connection terminals 29 and 31 to remove or attenuate line noises. The other ends of the first and second choke coils 30 and 32 are connected to a capacitor 34 disposed in the side wall of the filter box, and inside the first and second choke coils 30 and 32. Ferrites 36, which absorb low-frequency noise at frequencies in the low-frequency region, are inserted and fixed along the longitudinal directions of the first and second choke coils 30,32.

In addition, the top and bottom of the funnel shape, which is a magnetic body that forms a magnetic flux on both side openings of the anode cylinder 13 to form a magnetic flux uniformly in the working space 12 formed by the filaments 17 and the vanes 15. The pole pieces 33 and 35 are welded together.

Upper and lower shield cups 37 and 39 are hermetically welded to upper and lower portions of the upper and lower pole pieces 33 and 35, respectively, and the anode body is disposed on upper and lower portions of the upper and lower shield cups 37 and 39, respectively. The antenna ceramic 45 and the insulating ceramic 27 are hermetically welded to seal the inside of the vacuum chamber 13 with a vacuum.

In addition, ring-shaped magnets 41 and 43 are disposed on the outer surfaces of the upper and lower shield cups 37 and 39 to maintain a constant magnetic field distribution in the anode cylinder 13, and constitute an output portion of the magnetron. A cylindrical antenna ceramic 45 is insulated from the upper opening end of the upper shield cup 37 to insulate the antenna cap described later.

Further, in the drawing, an exhaust pipe 47 made of copper is joined to an upper end of the antenna ceramic 45, and near the inner central portion of the exhaust pipe 47, the vane is output to output high frequency oscillated in the resonance cavity. The end of the antenna 48 is fixed in the exhaust pipe 47 while the antenna 48 derived from 15 extends axially through the through hole 33b of the upper pole piece 33.

In addition, the outer surface of the exhaust pipe 47 protects the welded and fixed portion of the exhaust pipe 47 as well as prevents sparking due to electric field concentration and acts as a high frequency antenna, and simultaneously emits a high frequency output to the outside. The antenna ceramic 45 and the antenna cap 51 are placed on it.

In addition, the outer and outer yoke 53, 55 for determining the amount of magnetic flux in the anode cylinder 13 is connected to the outside of the anode cylinder 13, the anode cylinder 13 And a plurality of aluminum cooling fins 57 are disposed between the anode yoke 55 and the lower yoke 55 by the clamp member 55a fixed to the anode cylinder 13 and the lower yoke 55. 43) and covered by the upper and lower yokes 53 and 55 for forming a porcelain.

The first and second choke coils 30 and 32 are sufficiently insulated with an insulating enamel on the coil surface at 3.3V, as shown in FIGS. 2 to 7 to remove or attenuate line noises on AC power lines. The two wires are twisted together to form the filter circuit according to the inductor, capacitor, and L and C existing between the two wires.

In addition, the first and second external connection terminals 29 and 31 are connected to the choke coils 30 and 32 so that an alternating current between the two lines alternately reduces line noise.

Hereinafter, the effect of the cathode portion structure of the magnetron configured as described above will be described.

First, when power is applied through the first and second external connection terminals 29 and 31, the first external connection terminal 29 → the first filament electrode 23 → the upper shield hat 20 → the filament 17 → The lower shield hat 21 → the second filament electrode 25 → the second external connection terminal 31 is a closed circuit is configured to supply the operating current to the filament 17 is heated.

When the filament 17 is heated to a high temperature, it begins to emit hot electrons into the working space 12.

At this time, a strong electric field is formed in the working space 12 between the outer surface of the filament 17 and the vanes 15 by the driving voltage applied to the second filament electrode 25 and the anode, and the strong electric field is a vane. Starting at (15) it leads to filament (17).

On the other hand, the magnetic flux generated from the two magnets (41, 43) is led along the lower poly (38) toward the working space 12, the guided magnetic flux proceeds to the upper pole piece 36 through the working space 12 While being distributed in a magnetic circuit consisting of the upper yoke 53, the lower yoke 55, the upper pole piece 33, the lower poly 35 and the working space 12, a high magnetic flux density in the working space 12 is achieved. Form.

Therefore, the hot electrons emitted from the surface of the hot filament 17 into the working space 12 travel toward the vane 15 or the anode body 13 by the strong electric field present in the working space 12 and at the same time the working space ( 12) It receives a force perpendicular to the direction of travel due to the strong magnetic flux density present in the circle and moves in a circular direction as the electrons advance toward the anode.

The movement of the electrons is made in all the working spaces 12, and the electrons form a group of electrons in accordance with the structural resonance circuit of the vanes 15, and the vanes 15 are repeatedly carried out to the vanes 15 having a high potential. ) Generates a 2450 MHz band (fundamental wave) microwave, which is a resonance frequency corresponding to the speed at which the electron group rotates.

Therefore, the microwave energy generated by the vanes 15 is transmitted to the output of the magnetron while being conducted through the antenna 49 and transferred to the cavity of the microwave oven through the antenna cap 51 connected to the outside.

On the other hand, even if the oscillation is ideally made in the anode cylinder 13, various microwaves are generated by temperature increase or reflection wave or impedance defects of the microwave and the magnetron, and most of the microwaves generated by the anode cylinder 13 are antennas ( It is conducted through 49) and various frequencies are loaded.

At this time, the filament 17 existing in the working space 12 is affected by the harmonics generated in the anode cylinder 13, which is a harmonic noise among the microwave energy, and the filament 17 acts as an antenna to transmit radio waves. To receive.

The received filament 17 transmits noise to the connected first and second filament electrodes 23 and 25. The filament electrodes 23 and 25 and the external connection terminals 29 and 31 are also connected to an external power source. Line noise is transmitted through the power line to apply power.

Accordingly, in order to remove or attenuate line noise propagated through the AC power line through the cathode part, two wires of the insulated first and second choke coils 30 and 32 are shown in FIGS. 2 to 7. Similarly, each of the windings on one ferrite 36, each winding and then twisting each other or twisting each other, or alternately winding to filter according to the L, C present between the inductor and capacitor and the two wires of the coil itself Configure the circuit.

At this time, the first and second external connection terminals 29 and 31 for supplying AC power to the filament 17 through the first and second filament electrodes 23 and 25 are twisted first and second choke coils. AC current between two alternating lines is connected to 30 and 32 to reduce line noise in reverse phase, and external connection terminals 29 and 31 can perform the same fastening, thus simplifying work. .

On the other hand, the filter inserted in the power line is a kind of low pass filter, the pass band frequency is mainly 50 / 60Hz commercial frequency. In the power supply line, considering the noise transfer mode, a filter is formed using a symmetrical component that reciprocates between the power supply lines in a form overlapping the load current.

The inductor used for the power supply line acts as a single L as shown in FIG. 8A or a mutual inductance M as shown in FIG. 8B.

8 (A) is inserted in series to the power line to block the noise transmitted between the power lines with a high impedance of Z = ω L, Figure 8 (B) is inserted between the lines of the power line to induce mutual induction M It suppresses the noise transmitted between the power line and the ground.

According to the cathode portion structure of the magnetron according to the present invention as described above, by improving the shape of the choke coil (30, 32) and the ferrite 36 to effectively remove the line noise leaking to the outside through the cathode portion of the device It can prevent the malfunction and at the same time reduce the cost by its simple structure.

Claims (6)

A filament 17 for emitting hot electrons, Filament electrodes 23 and 25 for supporting the filament 17, External connection terminals 29 and 31 for supplying power to the filament 17 through the filament electrodes 23 and 25; Choke coils 30 and 32 connected to the external connection terminals 29 and 31 so as to eliminate line noise transmitted through a power line; Cathode portion structure of the magnetron, characterized in that consisting of a ferrite (36) absorbing low-frequency noise transmitted through the power line. The method according to claim 1, The choke coil (30, 32) is a negative electrode structure of the magnetron, characterized in that insulated to be wound around one ferrite (36). The method according to claim 1, The choke coil (30, 32) is a magnetron structure of the magnetron, characterized in that the two wires are wound around the ferrite (36), respectively. The method according to claim 1, The choke coil (30, 32) is a magnetron structure of the magnetron, characterized in that the two wires are wound around the ferrite 36 and then twisted with each other. The method according to claim 1, The choke coil (30, 32) is the cathode structure of the magnetron, characterized in that the two wires are wound around the ferrite (36). The method according to claim 1, The choke coil (30, 32) is the cathode structure of the magnetron, characterized in that the two wires are wound alternately in the ferrite (36).