JPH0734351B2 - Filter case for magnetron - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a metal box containing a cathode terminal lead-out part of a magnetron and a filter circuit element connected to the part.
The present invention relates to a magnetron filter case including a metal lid that covers the opening of the box body.

2. Description of the Related Art Generally, a cathode terminal lead-out portion of a magnetron and a filter circuit element connected to the portion are housed in a filter case. The filter case covers a metal box body and an opening of the box body. It consists of a metal lid.

In the magnetron device provided with such a filter case, the leakage of electromagnetic waves leaked through the cathode terminal lead-out conductor of the magnetron to the outside of the device can be prevented by the shield action of the filter case and the filter circuit.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention By the way, in order to obtain a sufficient shielding effect by the filter case, a gap generated in the fitting portion between the box body and the lid body,
Especially, a gap having a length exceeding a predetermined value becomes a problem. Therefore, by caulking the fitting portion intermittently, a long gap is not formed in the fitting portion, but since the box body and the lid body are made of a relatively thin metal plate,
Due to the elasticity (springback) of the lid itself, a gap is created between the opening edge of the box and the peripheral edge of the lid, causing a problem that electromagnetic waves leak from the gap.

The present invention provides a magnetron filter case in which a gap between the opening edge of the box and the peripheral edge of the lid is substantially eliminated, and leakage of electromagnetic waves from the gap is prevented.

The magnetron filter case of the present invention contains a cathode box lead-out portion of the magnetron and a filter circuit element connected to the cathode terminal lead-out portion, and a metal box having a curl-shaped opening edge curled outward. A metallic lid body that covers the opening of the box body and has a bent portion with a U-shaped cross section on the periphery, and the curled opening edge of the box body with the U-shaped bent portion of the lid body Is inserted over the entire circumference, and further, the outside of the bent portion is caulked intermittently and a large number of groove grooves are provided on the outside of the bent portion,
A deformed portion is formed on the edge portion of the opening, and the edge portion of the opening is sandwiched between the inner and outer surfaces by the bent portion.

Action With such a configuration, the restoring force of the curled opening edge of the box body is larger than the restoring force of the U-shaped bent section of the lid, so that the opening can be performed even when external pressure is applied during assembly, transportation, or handling. A large gap does not occur between the deformed portion of the end edge portion and the groove of the bent portion having a U-shaped cross section, so that leakage of electromagnetic waves can be prevented.

Embodiment In the embodiment shown in FIG. 1, a metal box 5 containing a stem 2 serving as a cathode terminal lead-out portion of a magnetron 1 and a choke coil 4 having one end connected to a cathode terminal pin 3 of the stem 2.
Has an opening edge 6 curled outwardly over the entire circumference. The metal lid 7 for covering the opening of the box 5 has a bent portion 8 having a U-shaped cross section over the entire circumference. The other end of the choke coil 4 is connected to a through electrode of a through capacitor 9 attached to the side wall of the box body 5, and the choke coil 4 and the capacitor 9 are LC
Configure a filter circuit. Further, a frame-shaped yoke 10 and an annular permanent magnet 11 for exciting the magnetron 1 are provided on the outer surface side of the bottom of the box body 5, and the through hole at the bottom of the box body 5 has a magnetron at its peripheral portion. 1 metal tube part 12
Is in close contact with.

The lid 7 is fitted to the box 5 as shown in FIG. That is, in the inside of the bent portion 8 having a U-shaped cross section of the lid body 7, after the curled opening edge portion 6 of the box body 5 is inserted over the entire circumference, the bent portion 8 is subjected to intermittent caulking. This caulking process is obtained by pressing in the direction shown by the arrow in FIG. A large number of grooved grooves 13 are formed on the bent portion 8 that has been caulked as a processing trace, but the box body 5
The opening end edge portion 6 is strongly held between the inner and outer surfaces inside the bent portion 8 of the lid 7. Opening edge 6 at the position of the groove 13
Is flattened as shown in FIG. 3, but the action of returning tends to work due to the elasticity of itself. At this time, since the restoring force of the curled opening end edge portion 6 of the box body 5 is larger than the restoring force of the U-shaped cross-section bent portion 8 of the lid body 7, the deformed portion of the opening end edge portion 6 and the U-shaped cross-section bent portion. No large gap is formed between the groove 8 of the portion 8 and the groove 13, and therefore, leakage of electromagnetic waves can be prevented. In addition, the opening edge portion 6 other than the position of the groove 13 maintains a curled state as shown in FIG. 4, and also has an action of engaging with the bent portion 8 deformed from the position of the adjacent groove 13. Therefore, the box body 5 and the lid body 3 are three-dimensionally irremovably fitted in the overlapping portion.

Next, an example in which the effect of the present invention is confirmed will be described.

The magnetron filter case of the embodiment of the present invention having the structure shown in FIG. 2 and the conventional magnetron filter case having the same structure except that the opening edge of the box is not curled in the structure shown in FIG. The results of measurement by the loss measurement method for each of the shielding effects are shown in FIG. 5 as curve A and curve B, respectively. In FIG.
2450MHz = 2.45GHz for fundamental wave, 2.45GHz × N for Nth harmonic
Is.

As is clear from FIG. 5, the magnetron filter case (curve A) of the embodiment of the present invention has a frequency of 2 GHz as compared with the conventional magnetron filter case (curve B).
It can be seen that the shielding effect is improved by 5 to 7 bB between -18 GHz.

EFFECTS OF THE INVENTION Since the present invention is configured as described above, even if the metal box body and the metal box body are warped or deformed, not only can they maintain a close fitting state, but both Since the overlapping portions are three-dimensionally fitted, electromagnetic wave leakage can be almost completely shielded.

[Brief description of drawings]

FIG. 1 is a side sectional view of a magnetron filter case according to the present invention before fitting, FIG. 2 is a cutaway perspective view after fitting the filter case, FIG. 3 and FIG.
FIG. 5 is a side sectional view of a part of the filter case, and FIG. 5 is a diagram showing the shielding effect of the magnetron filter case of the embodiment of the present invention in comparison with the shielding effect of the conventional magnetron filter case. 1 ... Magnetron, 2 ... Stem, 4 ... Choke coil, 5 ... Box, 6 ... Open edge, 7 ... Lid, 8
...... Bent part.

Claims (1)

[Claims] 1. A metal box body for accommodating a cathode terminal lead-out portion of a magnetron and a filter circuit element connected to the cathode terminal lead-out portion, and having a curled opening edge curled outward, and the box body. Of the metal cover having a bent portion having a U-shaped cross section at its peripheral edge, and the curled opening end edge portion of the box body extends over the entire circumference at the U-shaped bent portion of the lid body. By inserting and further caulking the outside of the bent portion intermittently and providing a number of groove grooves on the outside of the bent portion, a deformed portion is formed at the opening end edge portion, and the opening end edge portion is formed. A filter case for a magnetron, wherein the magnet is sandwiched between the inner and outer surfaces by the bent portion.