JPS6398940A - Magnetron - Google Patents

Abstract

PURPOSE:To maintain a high output efficiency and to restrict the unnecessary radiation from the input/output part, by extending an antenna lead in a desired length from the connection with strap rings vertical to the axis of an anode cylinder, penetrating a link hole furnished at a pole piece which is installed from the anode cylinder end surface, and extending it up to an output antenna. CONSTITUTION:A pair of strap rings 40 and 41 with different diameters mounted inside vanes 39 and connected alternately to the vanes, an output antenna 45 mounted in the axial direction of an anode cylinder 30, and an antenna lead 42 with one end connected to the strap ring 41 of the larger diameter, an extending part entered from the connection almost vertical to the axis of the anode cylinder 38, and the other end extended up to the output antenna 45, are provided. By providing the strap rings inside the vanes, the electric field distribution in the antenna lead extending space can be formed in a good shape, and the unnecessary radiation to the output side can be restricted. And by extending the antenna lead to combine much more with the electromagnetic field generated in a small resonant hollow, the output efficiency can be made higher.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetron, and more particularly to an improved anode structure and output F1η body that suppress unnecessary radiation from the magnetron input/output section.

BACKGROUND OF THE INVENTION In recent years, with the rapid spread of microwave ovens, the technology of microwave ovens has been relentlessly pursued in order to meet demands and goals in terms of both demand and supply, such as smaller size, lighter weight, and lower price. In view of the above-mentioned circumstances, magnetrons installed in microwave ovens are also required to be smaller, lighter, more efficient, have lower noise, and be lower in price. Figure 3 shows the layout of a conventional general magnetron. In the figure, 1 is an anode cylinder, 2 is a plurality of vanes arranged inside the anode cylinder, and 3 is arranged on both ends of the vane in the axial direction of the anode cylinder tube, alternately with the plurality of vanes every other vane. A strap ring consisting of two pairs of connected rings, 4 is an antenna lead, one end of which is connected to any one of a plurality of vanes at a desired position, and a coupling hole of a pole piece 5 provided at the end of the anode cylinder. 6 through V↓ to an output antenna section 7 whose other end is disposed in the axial direction of the anode cylindrical tube. This antenna lead 4 is cut to the same length as the exhaust pipe 8 which becomes the exhaust path when evacuating the inside of the anode cylinder, and is integrally connected and fixed to the exhaust pipe at the cut part of the exhaust pipe as shown in the figure. .

The cathode section 9 is composed of a spiral filament arranged concentrically with the anode cylinder at the center of the anode cylinder, and end hats 10 and 11 are arranged at both ends of the helical filament. Each end hat is connected to a support lead 12, 13 arranged in the axial direction of the anode cylinder tube. Each support lead is silver-copper soldered to a cathode stem 14 made of a ceramic material disposed on the end face of the anode cylinder opposite to the output antenna part, and this cathode stem is connected via a silver-copper brazed cathode side tube 15. The anode is fixedly assembled on the end face of the anode cylinder. 16 is the pole piece on the cathode stem side, 17.18
19, 20 are permanent magnets, 21 are heat dissipation fins press-fitted into the anode cylindrical tube, 22 and 23 are yoke forming a magnetic circuit, Reference numeral 24 is a core choke coil, 25 is a Tatetsu capacitor, and 26 is a filter box.

One way to increase the magnetron output efficiency in such a conventional magnetron structure is to connect the antenna lead to the vane as close to the center of the anode cylinder as possible. By the way, as is clear from the structure of the conventional magnetron, since a strap ring is disposed at the end on the vane side, the connection position is limited due to the structure. In addition, considering the characteristics, the electromagnetic field distribution in the space near where the strap ring is arranged is extremely disordered as will be described later, so the connection position of the antenna lead to the vane should be adjusted to prevent unnecessary radio waves from coupling with the antenna lead. In a connection structure in which the anode is moved toward the inner wall of the anode cylinder, the efficiency decreases. In other words, it is difficult to say that the conventional magnetron structure satisfies both high output efficiency and suppression of unnecessary radiation at the same time.

FIG. 4 shows the electric field distribution on the vane side end face of a conventional magnetron anode structure measured by the present inventors. In the figure, 27 is the inner surface of the anode cylinder, 28 and 29 are vanes facing each other within the anode cylinder, 30 to 33 are strap rings, and 34 is a portion to which an antenna lead is connected. From the figure, it can be seen that in the conventional structure in which the strap ring is placed at the end on the vane side, the electric field is greatly disturbed near the strap ring. It is also recognized that a certain amount of electric field exists in the space formed between the opposing vanes and into which the cathode portion is inserted and loaded. This indicates that a part of the microwave energy generated within the anode cylinder is combined with the cathode part, and it is thought that this disturbs the movement of electrons emitted from the cathode part. It is thought that this promotes unnecessary radiation toward the cathode stem side.

By the way, as a structure for making the magnetron smaller and lighter, a structure in which the output antenna section is provided in a direction perpendicular to the axis of the anode cylindrical tube is considered. Such a structure was developed in Japanese Patent Application Laid-Open No. 56-394.
This is shown in Publication No. 3.

However, the strap ring structure disclosed in this publication is considered to be arranged on both end faces of the vane, as mentioned above, and is not a structure for suppressing unnecessary radiation.

On the other hand, a unique magnetron structure is disclosed in US Pat. No. 4,310,786 by Beverly D., Kumpfer et al. The main feature of this structure is the support structure for the cathode section. That is, the cathode section is supported by a pair of pole pieces.

The second feature is a structure in which a pair of strap rings are arranged at the center of the vane in the axial direction of the anode cylindrical tube. The present inventors measured the electric field distribution at the vane side end of an anode structure in which such a strap ring is arranged inside the vane, and obtained the following results.

This electric field distribution characteristic is shown in FIG. In the same figure, 35
is the inner wall of the anode cylinder, and 38 and 37 are a pair of strap rings. There are two major differences in characteristics between this structure and conventional anode structures. The first point is that the electric field distribution on the end face of the vane is orderly, and the second point is that the electric field distribution is symmetrical with respect to the tube axis, and that the electric field distribution in the space between the opposing vanes is symmetrical with respect to the tube axis. Since the electric field strength is extremely weak, the coupling of microwave energy to the cathode portion is weak. That is, it is thought that if such an anode structure is used, the movement of electrons will be less likely to be disturbed by microwaves, and the suppression of unnecessary radiation that is coupled to the cathode portion and leaks will be significantly improved.

By the way, the output structure disclosed in the U.S. patent mentioned above, that is, the microwave energy derivation structure in which one end of the antenna lead is shaped into a loop and the tip is attached to the vane, is as follows.
It has the following disadvantages. This means that it is difficult to increase the output efficiency of the magneto to the level achieved by the conventional output derivation structure shown in FIG. The reason for this is due to the pair of strapping structures. In other words, the resonant frequency of the small resonant cavity formed by the adjacent vanes and the inner surface of the anode cylinder is determined by the inductance Lr and capacitance Cr of the cavity when there is no strap ring, and the capacitance caused by the loading of the strap ring, as is well known. C
It is related to s. Further, the ratio between C' and Cs needs to be set to an appropriate ratio from the viewpoint of oscillation mode separation.

In other words, in order to obtain with a pair of straps the visual value that was conventionally obtained with two pairs of strap rings, it is necessary to increase the length of the strap ring disposed within the small resonant cavity.

In other words, the diameter of the strap ring is required to be larger than that of the conventional method. For this reason, the connection position of the antenna lead to the vane is moved closer to the inner wall surface of the anode cylinder than in the past, resulting in weaker coupling and lower efficiency. If you dare to improve the efficiency using conventional technology, you can make the antenna lead longer, but from the above, increasing the length can only be achieved outside the anode cylinder, so as a result, it means lengthening the output antenna part. This necessitates miniaturization or an impractical configuration.

Problems to be Solved by the Invention As described above, according to the conventional magnetron structure, when strap rings are arranged on both end faces of the vane, the connection position of the antenna lead to the vane, which increases output efficiency, is close to the strap ring. Therefore, there is a problem in that it combines with the disordered electric field distribution near the strap ring and tends to cause unnecessary radiation.On the other hand, when the strap ring is placed inside the vane, the conventional structure has the problem that the output efficiency decreases. Ta.

The present invention solves these conventional problems and provides a compact magnetron that maintains high output efficiency and suppresses unnecessary radiation from the human output section.

Means for Solving the Problems In order to solve the above problems, the magnetron of the present invention includes a pair of strap rings arranged inside a plurality of vanes and alternately connected to every other vane; An antenna lead having one end connected to the large-diameter ring of the pair of strap rings is provided at approximately the center of any adjacent vane of the vane, and this antenna lead extends from the strap ring connection point to the anode cylindrical tube axis. The anode has a structure in which the anode is extended for a desired length in a direction perpendicular to the anode cylinder end face, and is passed through a coupling hole provided in a pole piece attached to the anode cylinder end face to extend to the output antenna section.

Function: With the above configuration, the antenna lead is connected to the two vanes via the strap ring, and the degree of coupling can be increased by substantially lengthening the extension of the antenna lead within the small resonant cavity. By providing an antenna lead extension perpendicular to the axis of the anode cylindrical tube, the electric field coupling of the antenna lead can be increased and output efficiency can be increased, while the strap ring is placed inside the vane to create an orderly electric field distribution space. The antenna lead can be extended inside the antenna, and unnecessary radiation can be suppressed.

Example An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a sectional view of a main part of a magnetron showing an embodiment of the present invention, and FIG. 2 is a perspective view of the main part.

In the figure, 38 is an anode cylinder, 39 is a plurality of vanes disposed within the anode cylinder, 40 and 41 are arranged on the same plane approximately in the center of the anode cylinder in the axial direction of the vanes, and a plurality of vanes and A pair of strap rings 42 with different diameters are connected alternately, and 42 is an antenna lead, one end of which is connected to a large diameter strap ring 40 at approximately the center of adjacent vanes of a plurality of vanes, and is connected to an anode cylinder. After extending the anode cylinder several times in a direction perpendicular to the tube axis, bending it in the direction of the axis of the anode cylinder, and extending it nearly on the same plane as the end face on the vane side, the pole piece 4 is attached from one end face of the anode cylinder.
The inside of the exhaust pipe 46, which is a component of the output antenna part 45, is bent to pass through the coupling hole 44 provided in the anode cylindrical tube 3, and after penetrating the coupling hole, an appropriate bent part is provided. It extends concentrically. The figure shows an assembly configuration diagram that occurs after the exhaust pipe and antenna lead are cut together, and one end of the antenna lead is also fixed in this way. 47 is a pole piece attached from the other end of the anode cylinder; 48 is an antenna side tube; 49 is a side tube made of ceramic material, which is one component of the output antenna section; 5
0 is the antenna cap.

In the configuration described in item 1, by arranging the strap ring inside the vane, the electric field distribution in the antenna lead extension space can be made orderly, unnecessary radiation to the output (till) can be suppressed, and the electromagnetic field generated in the small resonant cavity can be suppressed. By extending the antenna lead for more coupling, the output efficiency can be increased.

Note that the shape of the antenna lead may be a round bar, a plate, or a round bar partially shaped like a plate.

Effects of the Invention As described above, the magnetron of the present invention provides the following effects.

(1) By connecting the antenna lead directly to the strap ring placed inside the vane and extending it as desired within the small resonant cavity and extending to the output antenna section, high output efficiency is achieved while suppressing unnecessary radiation. be able to.

(2) To counter the deformation of the strap ring caused by the antenna lead being pushed toward the anode cylinder side due to the change in volume of the antenna lead that occurs when it is cut integrally with the exhaust pipe, the antenna lead has many bends and the anode cylinder tube By having an antenna lead section that extends in a direction approximately perpendicular to the axis, the stress that may occur when cutting the exhaust pipe can be sufficiently absorbed by the antenna lead, preventing deformation of the strap ring, resulting in a highly reliable magnetron. can be provided.

(3) By arranging a strap ring inside the vane, unnecessary radiation toward the cathode stem side can be sufficiently suppressed.

[Brief explanation of the drawing]

FIG. 4 is a cross-sectional view of a magnetron showing a conventional example, FIG. 4 is an electric field distribution diagram in a conventional anode structure, and FIG. 5 is an electric field distribution diagram in an anode structure which is the basis of the present invention. 38... Anode cylinder, 38... Vane,
40.41...Strap ring, 42...
...Antenna lead, 45...Output antenna section. Name of agent: Patent attorney Toshio Nakao and 1 other person
2 Figure N3 Figure 4 Figure 5

Claims (1)

[Claims] a plurality of vanes arranged radially within the anode cylinder; a pair of strap rings with different diameters arranged inside the vanes and connected to the vanes alternately; and an output arranged in the axial direction of the anode cylinder tube. an antenna portion; and a portion extending substantially perpendicularly to the anode cylindrical tube axis from this connection point where one end is connected to the large-diameter strap ring of the strap ring, and the other end extends to the output antenna portion. A magnetron having an antenna lead.