JPH10283944A - Magnetron - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the external leak of an undesired radiation by forming recessed portions protruding to a joining portion inner periphery side or protrusion portions alternately protruding to the joining portion inner periphery side and an outer periphery side in the 1/4 wavelength pitch of an arbitrary higher harmonic extending over the whole length of the joining portion outer periphery of a shield case and a shield case cap. SOLUTION: A shield case cap 7 is fitted to the opening end of a shield case 5, and is calked so as to form quadrangle pyramid shape recessed portions 8 extending over the whole periphery of the joining portion A thereof. The recessed portions 8 are formed so as to be in the pitch of 1/4 wavelength mm or less of a high frequency to be prevented, and simultaneously are calked so as to protrude to the inner periphery side of the fitting portion of the shield case 5 and the shield case cap 7. For example, when the prevention of the leak of the fifth harmonic is required, the fifth harmonic is 12.25 GHz so that the 1/4 length of the wavelength thereof is 6 mm. Accordingly, the pitch of the recessed portions 8 is set to 6 mm or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetron used for a microwave heater such as a microwave oven.

[0002]

2. Description of the Related Art A magnetron of this type generates unnecessary radiation in a large frequency band from a low frequency to a high frequency in addition to a fundamental oscillation frequency. The fundamental frequency of the magnetron is 2450 MHz, and its fifth harmonic is 12.25.
GHz, the sixth harmonic is 14.7 GHz, and the seventh harmonic is 1
7.15 GHz.

[0003] The current band of satellite broadcasting is 11.7-12.
It is 7 GHz, and the band required by the recent development of communication technology is about 18 GHz.

Therefore, if unnecessary radiation such as the fifth harmonic leaks from the magnetron, there is a problem that the reception of radio and television is interrupted.

Therefore, a conventional magnetron is disclosed in Japanese Utility Model Laid-Open Publication No.
As disclosed in Japanese Patent No. 2146, a filter including an inductor and a feedthrough capacitor is provided on the cathode input side of the magnetron, and unnecessary radiation leaking to the cathode input terminal side is removed by this filter.

In such a configuration, the inductor is housed in a shield case having a lower surface opening, and the lower surface opening of the shield case is closed with a shield case lid and caulked and fixed to the periphery of the shield case. By preventing a gap from being formed at the joint between the case and the shield case lid, unnecessary radiation leaking from the magnetron body into the shield case is prevented from leaking outside the shield case.

[0007]

However, the caulking portion of the shield case and the shield case lid has dimensional variation and deformation of each component and the elasticity of the material itself, so that there is a gap between the shield case and the shield case lid. Some gaps occur. Further, even when caulking is performed without a gap, deformation may occur due to external pressure or the like applied after manufacturing, and a gap may be generated in the caulked portion.

For example, a quarter wavelength of the fifth harmonic is 6
mm, and when a gap of about 6 mm or more is formed in the caulked portion, there is a problem that the fifth harmonic leaks to the outside.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a magnetron that prevents a gap from being formed at a joint between a shield case and a shield case lid and that does not leak unnecessary radiation to the outside.

[0010]

SUMMARY OF THE INVENTION The present invention provides a magnetron body, a filter connected to the input side of the magnetron body, a shield case for accommodating the filter, and a fitting covering the opening of the shield case. The shield case and the shield case cover are provided on the outer periphery of the joint between the shield case and the shield case cover at a pitch of a quarter wavelength of an arbitrary harmonic over the entire circumference. A concave portion protruding toward the inner peripheral side of the joining portion.

The present invention also provides a magnetron body, a filter connected to the input side of the magnetron body, a shield case for accommodating the filter, and a shield case fitted over the opening of the shield case. A cover, and a joint between the shield case and the shield case cover is provided at a pitch of a quarter wavelength of an arbitrary harmonic over the entire circumference at an inner circumferential side of the joint between the shield case and the shield case cover. And concave portions protruding outward are formed alternately.

The recess may have a quadrangular pyramid shape.

Further, the concave portion may have a triangular pyramid shape.

Further, the recess may have a conical shape.

Preferably, the recess is a groove having a substantially triangular cross section which is continuous in the longitudinal direction of the shield case.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

Reference numeral 1 denotes a magnetron main body, in which a cathode, a vane, a magnetic pole piece (not shown), and the like are arranged. The magnetron generates microwaves when the magnetron operates. Reference numeral 2 denotes a pair of permanent magnets disposed on both sides in the axial direction of the magnetron main body 1, and reference numeral 3 denotes a yoke surrounding the magnetron main body 1 and the permanent magnet 2. Reference numeral 4 denotes a plurality of heat sinks mounted on the outer periphery of the magnetron main body 1 for cooling the magnetron main body 1.

Reference numeral 5 denotes a shield case provided on the input side of the magnetron main body 1, which has a box shape with an entire lower surface opened, and has an opening formed in the center of the surface in contact with the magnetron main body 1. In this opening, the magnetron body 1
Of the cathode input terminals (both are not shown).

An inductor (not shown) is accommodated in the shield case 5 and is connected to a cathode input terminal of the magnetron body 1. This inductor includes a fillite core and electric wires (both not shown) wound around the outer periphery of the ferrite core.

Reference numeral 6 denotes a feedthrough capacitor connected to the inductor, which is fixed through the shield case 5. A filter is formed by the inductor and the feedthrough capacitor 6, and removes unnecessary radiation leaking from the cathode input terminal.

Reference numeral 7 denotes a shield case lid, which covers an opening on the lower surface of the shield case 5 and is fixed to the shield case 5 by caulking at a joint A thereof. Thus, the inside of the shield case 5 is closed, so that unnecessary radiation in the shield case 5 does not leak to the outside.

FIG. 3 is an enlarged sectional view of a joint A between the shield case 5 and the shield case lid 7. The shield case lid 7 is fitted to the open end of the shield case 5 and its joint A
Is crimped so as to form a quadrangular pyramid-shaped concave portion 8 over the entire circumference. The pitch P of the concave portion 8 is formed to be equal to or less than 分 の mm of the wavelength of the harmonic to be prevented, and protrudes toward the inner peripheral side of the fitting portion between the shield case 5 and the shield case lid 7. Caulked.

For example, when it is desired to prevent the leakage of the fifth harmonic, since the fifth harmonic is 12.25 GHz, its wavelength is about 24 mm, and the length of a quarter of the wavelength is 6 mm. Therefore, the pitch P of the recess 8 is set to 6 mm or less.

By forming the concave portion 8 at the joint between the shield case 5 and the shield case lid 7 and deforming the gap, it is possible to prevent the generation of a gap due to the elastic force of both parts, thereby preventing leakage of harmonics. it can.

In this embodiment, the shape of the recess 8 is a quadrangular pyramid, but it may be a triangular pyramid as shown in FIG. 4 or a cone as shown in FIG.
Pitch P is 1/4 mm of the wavelength of the harmonic to be prevented.
The same effects and advantages as those of the above-described embodiment can be obtained by being formed below.

Further, as shown in FIG. 6, the concave portion 8 may be a groove having a substantially triangular cross section continuous in the vertical direction of the shield case 5. By forming the groove, the shield case 5, the shield case lid 7 Is more reliably fixed, so that leakage of harmonics can be more reliably prevented.

As shown in FIG. 7, the concave portions 8 may be formed alternately on the outer peripheral surface and the inner peripheral surface of the fitting portion of the shield case 5 and the shield case lid 7, and with this configuration, the shield case 5 5 and the shield case lid 7 are more securely fixed, and leakage of harmonics can be more reliably prevented.

[0028]

According to the structure of the first aspect of the present invention, by forming a concave portion at the joint between the shield case and the shield case lid and deforming the same, it is possible to prevent the generation of a gap due to the elastic force of both parts. As a result, leakage of harmonics can be prevented.

Further, according to the configuration of the second aspect of the present invention, the joint between the shield case and the shield case lid is alternately formed with concave portions protruding on the inner peripheral side and the outer peripheral side of the joint, thereby deforming the joint. Since the generation of the gap due to the elastic force of the component can be more reliably prevented, the leakage of the harmonic can be prevented.

[Brief description of the drawings]

FIG. 1 is a side view of a magnetron showing an embodiment of the present invention.

FIG. 2 is a side view of the shield case according to the first embodiment.

FIG. 3 is a sectional view of the same.

FIG. 4 is a side view of a shield case showing another embodiment.

FIG. 5 is a side view of a shield case showing another embodiment.

FIG. 6 is a side view of a shield case showing another embodiment.

FIG. 7 is a cross-sectional view of a shield case showing another embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 magnetron body 5 shield case 6 feedthrough capacitor 7 shield case lid 8 recess

Claims (6)

[Claims] 1. A magnetron main body, a filter connected to an input side of the magnetron main body, a shield case accommodating the filter, and a shield case lid fitted over an opening of the shield case. The outer periphery of the joint between the shield case and the shield case lid projects at an interval of one-fourth wavelength of the arbitrary harmonic to the inner peripheral side of the joint between the shield case and the shield case lid over the entire circumference. A magnetron having a recess. A magnetron main body, a filter connected to an input side of the magnetron main body, a shield case accommodating the filter, and a shield case lid fitted over the opening of the shield case. At the joint between the shield case and the shield case lid, the pitch between the shield case and the shield case lid is set to an inner peripheral side and an outer peripheral side at a pitch of a quarter wavelength of an arbitrary harmonic over the entire circumference. A magnetron characterized by alternately forming projecting recesses. 3. The magnetron according to claim 1, wherein the recess has a quadrangular pyramid shape. 4. The magnetron according to claim 1, wherein the concave portion has a triangular pyramid shape. 5. The magnetron according to claim 1, wherein the concave portion has a conical shape. 6. The magnetron according to claim 1, wherein the recess is a groove having a substantially triangular cross section which is continuous in a longitudinal direction of the shield case.