JPH09167572A - Magnetron - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetron capable of certainly preventing noise leakage by electrically joining a shield case for shielding a cathode terminal side and a shield case cap by means of the shape of parts without depending upon junction due to calking only. SOLUTION: A magnetron comprising a filter connected to a cathode terminal of a magnetron main body and the filter and part of the cathode terminal covered by means of a shield case 1 and a shield case cap 2, wherein junction of the shield case 1 with the shield case cap 2 is made by allowing a taper- shaped protrusion part 2a provided at the tip end part of the shield case cap 2 to be pressurized into a through hole 1a provided at the end part of the shield case 1.

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 microwave heating equipment such as a microwave oven and radar. More specifically, the present invention relates to a magnetron in which a filter is provided on the cathode terminal side in order to suppress noise generated during operation of the magnetron, and the filter portion is covered by a shield case to reduce noise.

[0002]

2. Description of the Related Art In a magnetron, a microwave having a predetermined oscillation frequency (fundamental wave), for example, 2450 MHz is oscillated and taken out from an output antenna. In addition to the microwave having a predetermined frequency, noise of several hundred kHz to several tens GHz is generated. Occurs and leaks from the cathode terminal. When this noise leaks from the magnetron, it leaks as it is from the microwave oven and the like using the magnetron, which interferes with reception of radio, television, satellite communications, and the like. Therefore, in order to prevent these noises, as shown in FIG. 5, a filter composed of the ceramic capacitor 3 and the choke coil 4 is provided on the cathode terminal 5 side to block noise on the line and shield the cathode terminal 5 side. Noise radiated in the air by being covered by the case 1 and the shield case lid 2 is prevented from leaking to the outside. In FIG. 5,
The magnetron body is not shown, and only the filter portion connected to the input end 6 and the cathode terminal 5 of the magnetron body is shown.

Inside the main body of the magnetron, particularly harmonics, which are integral multiples of the fundamental wave, are easily generated. Of the harmonics, the 5th harmonic (5 times the fundamental wave 2450 MHz, 1
2.25 GHz) also matches the frequency band of satellite broadcasting,
There is a demand for noise suppression, and regulations are becoming more stringent, especially in Europe.

As a conventional noise suppressing means, a filter and a shield case are used as described above. A filter connected to the cathode terminal prevents noise on the low frequency side, and a shield case radiates from the cathode terminal. It also prevents the leakage of high frequency noise. Therefore, the shield case and the shield case lid are also joined to prevent noise from leaking.

A conventional method of joining a shield case and a shield case lid is, for example, as disclosed in Japanese Patent Laid-Open No. 63-221536, a flange portion is provided at an end of the shield case and the flange portion is used as the shield lid. A method is adopted in which the caulking is performed by fitting the cavity into the cavity provided in, and by caulking with a tooth profile having a pitch of ¼ of the wavelength of noise for preventing leakage. Further, Japanese Patent Publication No. 7-34351 discloses a method in which the end portion of the shield case is curled, the shield case lid is inserted over the entire circumference, and the outside is caulked intermittently by a large number of grooves. .

[0006]

As described above, the conventional shield case and shield case lid are joined by overlapping the shield case and the shield case lid and intermittently caulking them. That is, no processing is performed on the parts, and the countermeasure is mainly based on the shape of the caulking jig. Therefore, the parts are inexpensive, but the caulking strength varies due to dimensional tolerances of the parts and variations in the plate thickness of the parts. Further, the jig shape is deformed due to the wear of the jig, and the caulking strength is changed.
As a result, the joining force of the caulked portion decreases depending on the location.
In addition, since only caulking is performed, deformation due to the elasticity of the material itself occurs after caulking, and a gap is likely to occur.

[0007] Joining by caulking has many of these unstable elements, and stable joining of the two cannot be obtained. As a result, there is a problem in that a gap is formed in the front and rear of a portion where the caulking is insufficient, radio waves of unnecessary radiation leak, and other electronic devices are disturbed as noise.

The present invention solves such a problem and does not rely on only caulking to join the shield case and the shield case lid which shield the cathode terminal side, and ensures the electrical connection by the shape of the parts. An object of the present invention is to provide a magnetron capable of reliably preventing noise leakage.

[0009]

A magnetron according to the present invention is a magnetron in which a filter is connected to a cathode terminal of a magnetron body, and a portion of the filter and the cathode terminal is covered by a shield case and a shield case lid. The shield case and the shield case lid are joined by press-fitting a tapered protrusion provided at the tip of the shield case lid into a through hole provided at the end of the shield case. .

The through-holes and the protrusions are continuously provided at the end of the shield case and the tip of the shield case lid, and the pitch of the through-holes and the protrusions prevents the leakage of noise wavelength. It is preferable that the distance is set to 1/4 or less, because even if there is a small gap between the joints, it is possible to prevent the radio waves of unnecessary radiation from leaking and becoming noise.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the magnetron of the present invention will be described with reference to the drawings.

FIG. 1 is an explanatory view of a joint portion between a shield case and a shield case lid of the magnetron of the present invention, FIG. 2 is a perspective explanatory view of a joining process, and FIG. 3 is a through hole of the shield case and a projection portion of the shield case lid. FIG. 6 is an explanatory diagram of a dimensional relationship of.

The magnetron of the present invention has the same structure as the conventional magnetron with respect to the magnetron body which is the vacuum tube part and the filter part connected to the cathode terminal, and the description thereof is omitted. The present invention is characterized by the structure of the joint portion between the shield case and the shield case lid that covers the cathode terminal of the magnetron body and the filter portion connected to the cathode terminal.

As shown in FIGS. 1 and 2, the shield case of the present invention is provided with a through hole 1a at its end. Further, a projection 2a is provided at the tip of the shield case lid 2 so that it can be fitted into the through hole 1a of the shield case 1.
Is provided. As shown in FIGS. 1 and 2, the protruding portion 2a is preliminarily bent in a direction perpendicular to the tip portion thereof, and the tip portion of the shield case lid 2 encloses the end portion of the shield case 1. It has been folded, but it is not a perfect bag and the mouth opens,
The end of the shield case 2 is bent so that it can be easily inserted.

After using the thus formed shield case 1 to mount a choke coil and a capacitor forming a filter therein, the shield case lid 2 is covered. At this time, the ends of the shield case 1 and the shield case lid 2 are in the state shown by the solid lines in FIG. After that, when the tip of the shield case lid 2 is bent (caulked) to the shield case 1 side with a jig, as shown by the chain double-dashed line in FIG. 1, the protrusion 2a is fitted and fixed in the through hole 1a. To be done. That is, as shown in the explanatory view of FIG. 2, the protrusion 2a has a tapered shape with a thin tip and a thick root, such as a triangular shape. The tapered shape of the protrusion 2a has a through hole 1a at the tip.
Is smaller than the diameter of the through hole 1a, and its root portion is larger than the diameter of the through hole 1a. Therefore, at first, the protrusion 2a is easily inserted into the through hole 1a, and the protrusion 2a
Although the insertion is stopped at the root portion larger than the diameter of the through hole 1a, by further pressing (pressing) with a constant pressure, the mutual edge portions bite and are firmly fixed.

The dimensional relationship between the through hole 1a and the protrusion 2a is
For example, it is set as follows. First, the pitch P (see FIG. 3) of the through holes 1a and the protrusions 2a is formed to have the same size and is formed to, for example, about 3 to 6 mm. This is surely electrically short-circuited at the fitting portion between the through hole 1a and the protrusion 2a, but even if a gap is formed between them, it is difficult for a radio wave having a wavelength of four times or more the length of the gap to pass therethrough. By utilizing this property, the fifth harmonic (12.5 GHz: 1/4 wavelength) of the fundamental wave (2450 MHz) of the magnetron for microwave ovens, which has recently become a problem, is about 6.1 m.
This is to prevent the leakage of m).

The diameter D of the through hole 1a (see FIG. 3)
Is formed to have a thickness of, for example, about 1 to 3 mm. If the diameter is too large, high-frequency noise is likely to leak, so it is preferable that the diameter is small, and if it is too small, the fitting force with the protrusion 2a becomes weak, and both are taken into consideration. That is, the quarter wavelength of the fifth harmonic, which is a problem with high frequency noise, is about 6.1 mm, and if it is 3 mm or less, the leakage can be sufficiently prevented, and if it is 1 mm or more, the bonding force is sufficient. This is because it can be obtained.

Further, the width W of the root portion of the protrusion 2a (see FIG. 3)
(Refer to FIG. 3) and the height H (see FIG. 3) of the protrusion 2a is formed to be about 1 to 3 mm. If the width of the root part is about 1 mm larger than the diameter of the through-hole 1a, it is possible to obtain a sufficient joining force by biting into the edge part of the shield case and the shield case lid made of iron or the like and having a plate thickness of about 0.4 mm. is there.

When the tip of the shield case lid 2 is bent and fitted (caulked) on the side of the shield case 1 described above, it may be bent with a flat jig, and a relatively small force may be applied. The productivity can be improved and the equipment maintenance can be reduced, and the effect of electrical connection is constant and stable joining can be obtained. In this case, as shown in FIG. 4, the flange portion 1b, which is inevitably formed at the end of the shield case 1 at the time of drawing, is escaped and caulked, so that the pull-out strength of the shield case lid 2 is further improved. And more stable joining can be obtained.

[0020]

As described above, according to the present invention, the connection between the cathode terminal and the shield case covering the filter portion and the shield case lid is not simply caulked.
Since the fitting is performed by fitting the through hole and the protruding portion, the edge portion of the component is fixed by being bitten. As a result, it is possible to ensure reliable electrical connection and mechanical strength, and it is possible to sufficiently suppress microwave noise such as harmonics.

Also in terms of assemblability, it is not necessary to take an extra configuration in the shape of the caulking jig, so that stable productivity can be obtained and the life of the jig can be greatly improved.

Further, by escaping the flange portion at the end of the shield case to caulk, the removal strength of the shield case lid is improved, more stable joining is obtained, and a magnetron of high quality and high productivity can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a joint portion between a shield case and a shield case lid of a magnetron of the present invention.

FIG. 2 is a perspective explanatory view of a joining process between the shield case and the shield case lid of FIG.

FIG. 3 is an explanatory diagram of a dimensional relationship between a through hole of a shield case and a protrusion of a lid.

FIG. 4 is a diagram showing a state of a joint portion when a flange is formed on an end portion of a shield case.

FIG. 5 is a diagram showing a state in which a filter is connected to the cathode terminal of the magnetron.

[Explanation of symbols]

 1 Shield case 1a Through hole 2 Shield case lid 2a Projection

Claims (2)

[Claims] 1. A magnetron in which a filter is connected to a cathode terminal of a magnetron body, and a portion of the filter and the cathode terminal is covered by a shield case and a shield case lid, wherein the shield case and the shield case lid are joined together. A magnetron formed by press-fitting a tapered protrusion provided at the tip of the shield case lid into a through hole provided at the end of the shield case. 2. The noise through which the through hole and the protrusion are continuously provided at the end of the shield case and the tip of the shield case lid, and the pitch of the through hole and the protrusion prevents leakage. The magnetron according to claim 1, wherein the magnetron is provided so as to have a wavelength of ¼ or less.