JPS6398936A - Magnetron - Google Patents

Abstract

PURPOSE:To restrict the unnecessary radiation from the input/output part and to maintain a high operational rate, by providing a pair of strap rings connected alternately to plural vanes inside the plural vanes, and an antenna lead with an end connected to an optional vane. CONSTITUTION:Plural vanes 39 arranged radially in an anode cylinder 38, a pair of strap rings 40 and 41 mounted in the vanes and connected alternately to the vanes, and an output antenna 46 mounted in the axial direction of the anode cylinder are arranged, while an antenna lead 42 with one end connected to a specific position of the side surface of an optional vane in the axial direction of the anode cylinder, and the other end extended up to the output antenna is provided. By arranging the strap rings 40 and 41 inside the vanes 39, the electric field distribution in the antenna extending space is formed in a good shape, and the unnecessary radiation transmitting along the antenna lead can be restricted. And, since there is no strap ring at the side surface of the vanes, the antenna lead can be connected to the vanes closely to the operation space, the combination with the microwave energy can be made larger, and a high operational rate can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to magnetrons, and more particularly to improved anode structures and output structures that suppress unnecessary radiation from magnetron input/output sections.

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 the demands and reputations of both supply and demand for smaller size, lighter weight, and lower prices. Considering the above circumstances, the magnetron installed in this microwave oven has been made smaller, lighter, more efficient, and has lower noise.
There is a demand for lower prices. The structure of a conventional general magnetron is shown in FIG. In the figure, 1 is an anode cylinder, 2 is a plurality of vanes arranged in the anode cylinder, 3 is a vane anode 1': arranged at both ends of the J tube axis, and alternately with a plurality of vanes. A strap ring consisting of two pairs of rings connected every other pair, 4 is an antenna lead, one end of which is connected to any one of the plurality of vanes at a desired position, and a pole piece provided at the end of the anode cylinder. 5 and extends to an output antenna section 7 whose other end is arranged in the axial direction of the anode cylindrical tube. The antenna lead 4 is cut at the same time as the exhaust pipe 8 which serves as an exhaust path when evacuating the inside of the anode cylinder, and is integrally connected and fixed to the exhaust pipe at the cut portion 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 one anode cylindrical 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 has a cathode side tube 15 soldered with silver-copper. The anode is fixedly assembled to the end face of the anode cylinder through the anode. 16 is the pole piece on the cathode stem side, 17.
18 is a dielectric member and metal tube for suppressing unnecessary radiation toward the power/l-dostem side, 19.2o is a permanent magnet, 21 is a heat dissipation fin press-fitted into the anode cylindrical tube, and 22.23 forms a magnetic circuit. Yoke to do, 24 is core person choke coil, 2
5 is a condenser, 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. However, 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 positions are limited. 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 west 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 Patent 1 α4.310.786 by Beverly D., Kurnpfer 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. Also the second
is characterized by a structure in which a pair of strap rings are placed in the axial center of one anode cylindrical tube of the vane. The inventors
For an anode structure in which such a strap ring is placed inside the vane, the electric field distribution at the end of the vane was measured and the following results were obtained. This electric field distribution characteristic is shown in FIG. In the figure, 35 is an anode cylinder inner wall, and 36 and 37 are a pair of strap rings.

There are two major differences in characteristics between this structure and the conventional anode structure.
There are points. The first point is that the electric field distribution on the vane side end face is orderly, and the second point is that the electric field distribution is symmetrical with respect to the tube axis, and the electric field in the space between the opposing vanes. Since the 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 above-mentioned US patent, that is, the microwave energy deriving structure in which one end of the antenna lead is formed into a loop shape and the tip thereof is connected to the vane has the following disadvantages. This means that it is difficult to increase the output efficiency of the magnetron to the level achieved by the conventional output derivation structure shown in FIG. The reason for this is due to the pair of strap ring 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 L' and capacitance Cr of the cavity when there is no strap ring, as is well known.
and the volume caused by strap ring loading, tCI
is related. Further, the ratio of Cr 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 capacitance value 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 efficiency using conventional technology, you can make the antenna lead longer, but as mentioned above, this can only be achieved outside the anode cylinder, so as a result, it is necessary to make the output antenna part longer. This means that we are forced to go backwards toward miniaturization or to create 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 that it is likely to combine with the disordered electric field distribution near the strap ring and cause unnecessary radiation. On the other hand, when the strap ring is placed inside the vane, it is not possible to achieve high output efficiency with the conventional configuration. The problem was that it couldn't be done.

The present invention solves these conventional problems and provides a magnetron that is compact and has excellent performance, which can suppress unnecessary radiation from the input/output section and maintain high output efficiency.

Means for Solving the Problems In order to solve the above-mentioned problems, the magnetron of the present invention includes a pair of strap rings that are connected to the inside of a plurality of vanes alternately at every other vane, and a pair of strap rings that are connected alternately to the plurality of vanes. The antenna lead has one end connected to two vanes.

Operation With the above configuration, the antenna lead is arranged in a space within the circular plane of the anode where the electric field distribution is orderly, so coupling with unnecessary modes is suppressed and unnecessary radiation propagating through the antenna lead is suppressed. In addition, since a strap ring was previously provided, there was a restriction in moving the connection position of the antenna lead to the vane closer to the working space side, but by placing the strap ring inside the vane, it was difficult to connect the antenna lead to the vane. The connection position can be placed on the working space side, and the coupling with the microwave energy can be made thicker, resulting in higher output efficiency.

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 inside the anode cylinder, and 40 and 41 are arranged on the same plane of the anode cylinder in the axial direction, and are mutually connected to the plurality of vanes. A pair of strap rings with different diameters are connected every other time, and 42 is an antenna lead, one end of which is connected at a predetermined position on the side end surface of any one of the plurality of vanes in the axial direction of the anode cylindrical tube. ing. This antenna lead is bent at an appropriate bend 45 in front of a coupling hole 44 provided in a pole piece 43 attached to the anode cylindrical end surface.
After passing through the coupling hole 44 1'j, an appropriate bent portion is provided again, and the output antenna part 46 is arranged in the axial direction of the anode cylindrical tube.
It extends concentrically inside the exhaust pipe 47 which is a component of the exhaust pipe 47. The figure shows an assembly configuration diagram after cutting the exhaust pipe and the antenna lead together, and one end of the antenna lead is also fixed as shown in the figure. The distance from the anode cylindrical tube axis to the position where the antenna lead is connected to the vane is approximately the same distance as the distance from the anode cylindrical tube axis to the large diameter strap ring. 48 is a pole piece attached from the other end of the anode cylinder, 49 is an antenna side tube, 50 is a side tube made of ceramic material and is a single groove component of the output antenna portion, and 51 is an antenna cap.

In the above configuration, by arranging the strap ring inside the vane, the electric field distribution in the space in which the antenna lead extends can be made orderly, and unnecessary radiation to the output side can be suppressed. In addition, since no strap ring is arranged on the end face of the vane, the connection position of the antenna lead to the vane can be moved closer to the working space side, increasing coupling with microwave energy and achieving high output efficiency. Can be done.

Furthermore, since one end of the antenna lead is connected to the vane, the exhaust pipe can be cut in the same way as in the conventional case.

In the present invention, the connection surface of the antenna lead to the vane is limited to the end surface on the vane side, and the connection position is not limited to the one embodiment of the present invention as long as the output efficiency can be maintained at a high level. In addition, various conventional techniques for increasing output efficiency (for example, loop-shaped wiring) may be used for the wiring of the antenna lead. You may move the connection to the opposite side.

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

1) By arranging the strap ring inside the vane, the electric field distribution in the space in which the antenna lead extends can be made orderly, and unnecessary radiation propagating through the antenna lead can be suppressed.

(2) Since there is no strap ring on the end face of the vane side, the antenna lead can be connected to the vane close to the working space, and the coupling with microwave energy can be increased, resulting in high output efficiency.

(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 sectional view of a conventional magnetron, FIG. 4 is an electric field distribution diagram in a conventional anode assembly, and FIG. 5 is an electric field distribution diagram in an anode assembly of the present invention. 3rd... Anode cylinder, 39... Vane,
40.41...Pair of strap rings, 42
...Antenna lead, 46...Output antenna section. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Turei 2 x Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] a plurality of vanes arranged radially within the anode cylinder; a pair of strap rings arranged inside the vanes and connected to the vanes alternately; and an output antenna section arranged in the axial direction of the anode cylinder; and an antenna lead having one end connected to a predetermined position on a side end surface in the axial direction of an anode cylindrical tube of the vane and the other end extending to the output antenna section.