JPH044683B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a magnetron in which a metal exhaust pipe also serves as an electromagnetic wave emission terminal.

Conventional structure and its problems In general, a magnetron used in a microwave oven, etc., consists of a cathode 1, a stem 2 for leading out the cathode terminal, an anode cylinder 3, an anode vane 4, a magnetic pole piece 5, and a seal. It includes a wearable metal cylinder 6, a ceramic ring 7, an exhaust pipe 8 made of a soft metal such as copper, and an electromagnetic wave guiding conductor 9 made of a soft metal such as copper.
The electromagnetic wave deriving conductor 9 that extends from the anode vane 4 and passes through the small hole 10 of the magnetic pole piece 5 enters the exhaust pipe 8 and is connected to the crush sealing part 11 of the exhaust pipe 8, as shown in FIG. They are crimped together, and the exhaust pipe 8 also serves as an electromagnetic wave emission terminal. In addition, 12 and 13 in the figure are magnetic flux concentration yoke plates, 1
4 and 15 are annular permanent magnets, and 16 is a frame-shaped yoke, which constitute an external excitation circuit for the magnetron.

By the way, as the electromagnetic wave deriving conductor 9, the second
As shown in the figure, a flat metal rod with a rectangular cross section that is bent in the thickness direction is used. Therefore, when the exhaust pipe 8 is crushed and pinched off together with the conductor 9 in the final stage of the exhaust process, that is, when the crushed sealing part 11 is formed, the conductor 9 is almost never eccentric in its width direction, and is always The conductor 9 was crimped near the center of the crush sealing part 11, and predetermined output characteristics could be obtained. But for that,
It is important to match the direction of compression during pinch-off with the thickness direction of the conductor 9, and determining the direction of compression requires a considerable amount of time and effort. Furthermore, since the small hole 10 of the magnetic pole piece 5 is circular, there is a risk that the conductor 9, which has slightly expanded due to crushing during pinch-off, is likely to come into contact with the inner peripheral surface of the small hole 10.

Therefore, as shown in FIG. 3, it is conceivable to use an electromagnetic wave deriving conductor 12 made of a metal rod with a circular cross section. However, unless the cross-sectional area of the conductor 12 is made larger than before, the mechanical strength in the width direction will be insufficient, and the conductor 12 will tend to be eccentric. Not only does this eccentricity cause a change in the output characteristics, but also the conductor 12 is crimped at a position away from the center of the crushed sealing part 11.
The risk of contacting the conductor 12 with the inner circumferential surface of the conductor 12 increases. Furthermore, increasing the cross-sectional area of the conductor 12 not only increases cost but also increases the amount of conductor elongation during compression, which also increases the risk of contact.

OBJECTS OF THE INVENTION Therefore, an object of the present invention is to provide a magnetron in which compression during pinch-off is not limited to one direction, and in which the electromagnetic wave deriving conductor is hardly eccentric.

Structure of the Invention In the magnetron of the present invention, a metal rod with a circular cross section is used as the conductor for deriving electromagnetic waves, and a narrow part is provided between the base end of the exhaust pipe and the crushing sealing part. will be described in detail below along with embodiments shown in the drawings.

DESCRIPTION OF THE EMBODIMENTS In FIGS. 4 and 5, the electromagnetic wave deriving conductor 12 extending from the anode vane 4 is made of a copper rod-shaped body with a circular cross section. 14 and is integrally crimped. The exhaust pipe 13 has a constricted part 15 between a base end 13a hermetically soldered to the ceramic ring 7 and a crushing seal part 14, and the conductor 12 passes through the constricted part 15.

The narrowed portion 15 is obtained by pressing the exhaust pipe as in the conventional method, but a mandrel made of a hard metal wire is inserted into the exhaust pipe in advance.
The cross-sectional shape after pressing becomes approximately a figure 8 shape as shown in FIG. 6, and a generally circular opening 16 formed by the mandrel is obtained in the center thereof, and the conductor 12 is loosely inserted into this opening 16. . The short diameter of the opening 16 can be set to approximately 1.1 to 1.6 times the diameter of the conductor 12. Further, the hollow portions 17 and 18 extending to both sides serve as air passages during evacuation.

Effects of the Invention In the magnetron according to the present invention configured as described above, the direction of compression during pinch-off can be arbitrarily selected from a rotation angle of 360 degrees around the tube axis. Further, even if a relatively small diameter conductor is used for the electromagnetic wave deriving conductor, there is almost no eccentricity, and a predetermined output characteristic can always be obtained. Furthermore, it is possible to eliminate the risk of the conductor coming into contact with the inner circumferential surface of the small hole of the magnetic pole piece.

[Brief explanation of drawings]

Fig. 1 is a side cross-sectional view showing a conventional magnetron and its external excitation circuit, Figs. 2 and 3 are cross-sectional views mainly showing the joint between the electromagnetic wave deriving conductor and the exhaust pipe, and Figs. Fig. 6 shows an embodiment of the present invention, Fig. 4 is mainly a sectional view of the joint between the electromagnetic wave deriving conductor and the exhaust pipe, Fig. 5 is mainly an exploded perspective view of the exhaust pipe, and Fig. 6 is It is a cross-sectional view of the narrow part of the same exhaust pipe. 12... Electromagnetic wave deriving conductor, 13... Exhaust pipe,
15...Narrowing part.

Claims (1)

[Claims] 1. An electromagnetic wave deriving conductor that extends from an anode vane and is in a metal exhaust pipe or that is crimped to a collapsed sealing part of the exhaust pipe is made of a metal rod with a circular cross section, and the exhaust pipe has a base end thereof and a A magnetron characterized by having a constricted part between it and a crushing sealing part.