JPS6398935A - Magnetron - Google Patents

Abstract

PURPOSE:To eliminate a deformation of strap rings and vanes, and to restrict the unnecessary radiation from the input/output part, by forming a pair of strap rings connected alternately to the vanes, and furnishing a cutting to make one end of an antenna lead connected to the strap rings in a flat form having a space. CONSTITUTION:Plural vanes 57 arranged radial in an anode cylinder 56, a pair of strap rings 58 and 59 arranged in the vanes and connected alternately to the vanes, and an output antenna 64 mounted vertical to the axis of the anode cylinder are arranged, while an antenna lead 60, in which a cutting 62 is formed to have a space same as or more than the diameter of the strap rings at one end of its flat portion 61, connected to the strap rings near the entrance of the cutting 62, and the other end is extended up to the output antenna, is provided. A stress to the antenna lead when it is cut off together with an exhaust pipe is absorbed by the flat portion 61 to eliminate the deformation of the strap rings and the vanes, and the unnecessary radiation transmitting along the antenna lead is restricted by the antenna lead connected directly to the strap rings arranged inside the vanes.

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 inconvertible radiation from magnetron input/output sections.

BACKGROUND OF THE INVENTION With the rapid spread of microwave ovens in recent years, the technology of microwave ovens has been relentlessly pursued in order to meet the demands and goals of both demand and supply, such as smaller size, lighter weight, and lower price. 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 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 L1 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 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.

Further, 9 is a cathode section, which is composed of a spiral filament arranged concentrically with the anode cylinder at the center of the anode port jJ, 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 pipe 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 is a dielectric member and a metal tube for suppressing unnecessary radiation toward the cathode stem side, 19 and 20 are permanent magnets, 21 is a radiation fin press-fitted into the anode cylindrical tube, and 22 and 23 are yoke forming a magnetic circuit. , 24 is core person choke coil, 25
is a d-conductor, 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 arranged at the end on the vane side, the drawing-1 connection position is 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 inner wall of the anode cylinder, the efficiency decreases. In other words,
It is difficult to say that the conventional magnetron structure is a structure that provides both high output efficiency and unnecessary radiation suppression 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 circular portion, 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. As can be seen from the figure, in the conventional structure in which the strap ring is arranged 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 coupled with the cathode part, and is thought to disturb the movement of electrons emitted from the cathode part. It is thought that unnecessary radiation toward the cathode stem side is promoted through the irradiation.

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 +1°ζ structure disclosed in this publication is considered to be arranged on both end faces of the vane as described above, and is not a structure for suppressing unnecessary radiation.

Meanwhile, Beverly D.
A unique magnetron structure is disclosed in US Pat. No. 4,310,786 by 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 36 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 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 strength in the space between the opposing vanes. This is because the coupling of microwave energy to the cathode part is weak. In other words, if such an anode structure is used, the movement of electrons will be disturbed by microwaves, and the suppression of unnecessary radiation that combines with the cathode portion and leaks out will be significantly improved.

By the way, the output structure disclosed in the above US patent, that is, the microwave energy deriving structure in which one end of the antenna lead is shaped into a loop and the tip is made into a vane, is as follows:
It has the following disadvantages. This is because it is difficult to increase the output efficiency of the magnetron to the level achieved by the conventional output derivation structure shown in Figure 3.The reason for this is 1.
Due to the pair of strap rings +Nr'IV. 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 of the cavity when there is no strap ring, the capacitance C, and the amount caused by the loading of the strap ring, as is well known. In addition, the ratio between C' and 03 needs to be set to an appropriate ratio from the viewpoint of oscillation mode separation.In other words, the capacitance value that was conventionally obtained by two pairs of strapping is changed to one pair of strap rings. In order to achieve this with a strap ring, it is necessary to increase the length of the strap ring disposed within the small resonant cavity. That is, the diameter of the strap ring must be larger than that of the conventional one. 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, weakening the coupling and causing a decrease in efficiency. If you want 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 it means lengthening the output antenna part as a result. This necessitates miniaturization or an impractical configuration. In order to improve this problem, the present inventors have already proposed a configuration in which the antenna lead is directly connected to the strap ring. An example of this +j, 1 construction is shown in Figure 6. In the figure, 38 is an anode cylinder, 39 to 4
8 is a vane, and 49.50 is a pair of strap rings, which are connected to the vanes in alternating fashion. 51
numeral 1111 is an antenna 1111 tube arranged from the anode cylinder in a direction perpendicular to the axis of the anode cylindrical tube, 52 is a ceramic side tube that is silver-copper brazed to the antenna 11111 tube, and 53 is an exhaust gas that is silver-copper brazed to the ceramic side tube. It's a pipe. Reference numeral 54 denotes an antenna lead, one end of which is connected to a strap ring, which is arranged concentrically within the coupling hole 55, the antenna fill pipe, the ceramic side pipe, and the exhaust pipe, and is evacuated after evacuation within the anode cylinder to a predetermined level. It is cut and sealed integrally with the pipe, and the other end is identified at this cut. The dashed dotted line in 1 indicates the exhaust pipe and antenna lead before cutting, and they are cut in the direction indicated by the arrow in the figure. At this time, due to the volume change of the antenna lead, the antenna lead is pushed toward the anode cylinder side, and the strap ring connected to the antenna lead is deformed toward the center of the anode cylinder, and the vane (38 in the figure) to which this strap ring is connected is Also, due to stress during cutting, the straps may bend toward the adjacent vane (39 in the figure), and in the worst case, the strap rings or vanes may come into contact with each other, making it impossible to operate normally.

Problems to be Solved by the Invention As described above, when using a configuration in which a strap ring is provided inside the vane as a means for suppressing unnecessary radiation and the antenna lead is directly connected to the strap ring as a means for increasing output efficiency, the antenna lead is connected inside the vane. There was a problem in that the strap ring and vane were deformed during the cutting and sealing process of the exhaust pipe, making it impossible for the magnetron to operate normally.

The present invention solves these conventional problems and suppresses unnecessary radiation from the input and output parts by eliminating deformation of the strap ring and vane on the inner wall surface of the anode cylinder after vacuum film treatment inside the anode cylinder. The present invention provides a magnetron that is compact and has excellent performance while maintaining high output efficiency.

Means for Solving the Problems In order to solve the above problems, the magnetron of the present invention includes a pair of strap rings inside a plurality of vanes, which are alternately connected to every other vane, and the strap rings. One end of the antenna lead connected to the anode is made into a flat shape, and a notch with a predetermined gap is formed in this flat part, and the other end is connected to the strap ring near the entrance of this notch, and the other end is connected to the anode cylindrical tube shaft. The output antenna section is fixedly supported by extending to an output antenna section disposed perpendicularly to the output antenna section.

Function: With the above configuration, the flattened portion of the antenna lead absorbs the stress applied to the anode cylinder side when the antenna lead is cut integrally with the exhaust pipe, thereby preventing deformation of the strap ring and vane.

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 magnetron showing an embodiment of the present invention, and FIG. 2 is a perspective view of the main parts thereof.

In the figure, 56 is an anode cylinder, 57 is a plurality of vanes disposed within the anode cylinder, 58 and 59 are arranged on the same plane approximately at the center of the anode cylinder in the axial direction of the vanes, and are staggered with the plurality of vanes. A pair of strap rings 60 of different diameters are connected every other time to the antenna lead, and one end is attached to any adjacent vane of the plurality of vanes (57a in FIG. 2).

57b) is connected to a large-diameter strap ring 59 at approximately the center j'' lS.The strap ring connecting end of this antenna lead has a flat shape 61 of a predetermined length.
This flattened portion 61 is provided with a notch 62 having a gap equal to or larger than the diameter of the strap ring. Further, the flattening direction of the flattened portion is the vane 57.
It is placed so that it faces oppositely. One end of the antenna lead having such a structure is connected to the strap ring near the entrance of the notch. This connection may be brazed or caulked. Therefore, even after assembling the connection with the strap ring, there is a cut 3' from this strap ring connection part.
The flattened portion is formed so that a predetermined length of the notch gap remains until reaching the innermost part of the lS.

The antenna lead extends from this strap ring connection point in a direction perpendicular to the axis of the anode cylinder, passes through a coupling hole 63 provided on the side surface of the anode cylinder, and extends to the output antenna section 64 at the other end. This output antenna section 64 includes a ceramic side pipe 65, an exhaust pipe 66 and an antenna cap 6.
7, and the antenna lead is cut and sealed integrally with the exhaust pipe. Therefore, the other end of the antenna lead is fixedly supported by the J41 pipe as shown in the figure. 68
is a cathode part arranged concentrically with the anode cylinder in the center of the anode cylinder, and is composed of a spiral filament, and end halos (89.70) are provided at both ends of the cathode part. Each end hat is connected to a support lead 71, 72 arranged in the axial direction of the anode cylinder tube. These support leads are supported by silver-copper soldering to a cathode stem 73 made of a ceramic material disposed at one end surface (ill) of the anode cylinder.

The cathode stem is a silver-copper brazed cathode side tube 74.
The anode is assembled by welding to the end face of the cylinder via the anode. 75.7
6 is the pole piece, 77.78 is the permanent magnet, 79.80
81 is a radiating fin press-fitted into the anode cylindrical tube, and 82 and 83 are heat insulating plates that insulate the permanent magnet from radiant heat from the anode cylindrical tube. 84 is a filter box, 85 is a choke coil, and 86 is a feedthrough capacitor.

In the above configuration, when the antenna lead is pushed toward the anode cylinder side due to the volume change at the cut portion of the antenna lead that occurs when the other end of the antenna lead is cut and sealed integrally with the exhaust pipe, one end of the antenna lead is cut. By absorbing the above-mentioned pressing force by the flattened portion having the recessed portion, deformation of the strap ring near the antenna lead connection portion or deformation of the vane to which the strap ring is connected could be eliminated.

It is obvious that the fixed end of the exhaust pipe of the antenna lead should also have a desired flat shape.

Further, in the above embodiments, the base material of the antenna lead was described as a round bar, but it may be a plate material having a desired thickness. Even in this case, if the thickness of the matrix does not match the gist of the present invention, processing is performed so that both ends of the antenna lead have a desired flattened shape.

Effects of the Invention The magnetron of the present invention provides the following effects.

(1) By making the antenna lead at the connecting end of the strap ring flat with a notch, this flat part absorbs the stress of the antenna lead when it is cut integrally with the exhaust pipe, eliminating deformation of the strap ring and vane. can do.

(2) The antenna lead arrangement structure is directly connected to the strap ring placed inside the vane, which makes it possible to orderly distribute the electric field in the space in which the antenna lead extends, and to increase the coupling with microwave energy, so there is no need to propagate through the antenna lead. It is possible to suppress radiation and achieve high output efficiency.

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

(4) By making the flattened plane of the antenna lead face the vane, even if the flattened plane has a large area, it is possible to arrange the antenna lead while minimizing disturbances in the electromagnetic field distribution within the small resonant cavity.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a magnetron showing an example of a magnetron showing an embodiment of the present invention, FIG. 4 is an electric field distribution diagram in a conventional anode structure, FIG. 5 is an electric field distribution diagram in an anode structure of the present invention, and FIG. The figure is a cross-sectional view of another conventional magnetron. 56... Anode cylinder, 57... Vane,
58, 59...Pair of strap rings, 6
0... Antenna lead, 61... Flat shaped part, 62... Notch part, 64... Output antenna part. Name of agent Patent attorney Toshio Nakao and one other person 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 provided in a direction perpendicular to the anode cylinder tube axis. A notch having a gap equal to or larger than the diameter of the strap ring is formed in the antenna part and the flattened part at one end, and is connected to the strap ring near the entrance of the notch, and the other end is connected to the output antenna. a magnetron having an antenna lead extending to the top of the magnetron;