JPS6398937A - Magnetron - Google Patents

Abstract

PURPOSE:To restrict the unnecessary radiation and to maintain a high output operation rate, by providing a pair of strap rings connected alternately to plural vanes inside the vanes, and providing an antenna lead whose one end is connected to a strap ring with a larger diameter, extending in the axial direction of an anode cylinder. CONSTITUTION:While a pair of strap rings 40 and 41 with different diameters arranged inside vanes 39 connected altarnately to the vanes are arranged, an antenna lead 42 with one end connected to a strap ring of the larger diameter side, extending from the connection in the axial direction of an anode cylinder 38, penetrating a pole piece 43 provided at a linking hole 44, and with the other end extended up to an output antenna 46, is provided. By arranging the strap rings inside the vanes, the electric field in the antenna lead extending space is formed in a good shape, and the unnecessary radiation to the output side can be restricted. And, since the antenna lead is arranged in a highly dense electric field space through the strap rings, the combination with the microwave energy can be made larger sufficiently, and a high output efficiency 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 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 designed to be smaller, lighter, more efficient, and have 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 and extends to an output antenna section 7 whose other end is disposed 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 disposed concentrically with the anode cylinder at the center of the anode cylinder, and entnodes 10 and 11 are arranged at both ends of the helical filament.

Each node is connected to a support lead 12.13 arranged in the axial direction of the anode cylinder tube. Each support lead is soldered with a silver weight to a cathode stem 14 made of ceramic material arranged on the axis side of the anode cylindrical tube opposite to the output antenna part, and this cathode stem is connected to a cathode side tube 15 which is soldered with silver copper. The anode is fixedly assembled to the end face of the cylinder via the anode. 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, 19.20 is a permanent magnet, 21 is a heat dissipation fin press-fitted into the positive cylindrical tube, and 22.23 is a joint forming a magnetic circuit. Iron, 24 is core person choke coil, 2
5 is a feedthrough capacitor, and 26 is a filter box.

One means of increasing the magnetron output efficiency in such a conventional magnetron structure is to arrange the connection position of 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, the conventional magnetron structure cannot be said to be a structure that simultaneously satisfies both high output efficiency and unnecessary radiation suppression.

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 an anode cylinder inner wall surface, 28 and 29 are vanes facing each other in the anode cylinder, 30 to 33 are strap rings, and 34 is a portion to which an antenna lead is connected. From the figure, the conventional method of placing a strap ring on the end of the vane side is also W.
In the structure, it is observed that 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 part of the microwave energy generated within the positive birch cylinder is coupled with the cathode part, and is thought to disturb the movement of electrons emitted from the cathode part. This is thought to encourage unnecessary radiation toward the cathode stem.

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

However, the strampling 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 lateral radiation.

On the other hand, Reverly D, Kump f e
A unique magnetron structure is disclosed in US Pat. 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 the fifth
As shown in the figure. In the figure, 35 is an anode cylinder inner wall, 36.
37 is 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.
The second point is that the electric field distribution is quite symmetrical with respect to the tube axis, and the electric field strength in the space between opposing vanes is extremely weak, so the coupling of microwave energy to the cathode is weak. It is. In other words, if such an anode structure is used, it is considered that the suppression of unnecessary radiation, which occurs when the movement of electrons is disturbed by microwaves, forms a cone, combines with the cathode portion, and leaks, is considered to be significantly improved.

By the way, the output structure disclosed in the above-mentioned US patent, which is a microwave energy derivation structure in which one end of the Nawachi antenna lead is formed into a loop shape and the tip thereof is connected to the vane, has the following disadvantages. That is, the inner cone allows the output efficiency of the magnetron to be reduced to the efficiency achieved by the conventional output-only structure shown in FIG. The reason for this is due to the pair of strap ring structures. That is, to determine the resonant frequency of the small resonant cavity formed by the nine adjacent vanes and the inner surface of the anode cylinder, the inductance Lr and capacitance Cr of the cavity when no strap ring is used, as is well known.
and the capacitance Cs caused by strapping loading. Further, the ratio of Cr and 08 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. That is, it requires a larger strap ring 'B' than 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, and the 9-coupling becomes weaker, resulting in a decrease in efficiency. If you dare to improve the efficiency using conventional technology, you can make the antenna lead longer, but as mentioned above, increasing the length can only be achieved outside the anode cylinder, so as a result, it means lengthening the output antenna part. Therefore, it is necessary to go against the trend of 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. There was always a problem if I couldn't do it.

The present invention solves these conventional problems and provides a compact magnetron with excellent performance that suppresses unnecessary radiation from the input/output section and maintains 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 the plurality of vanes, which are alternately connected to every other vane; An antenna lead having one end connected to the larger diameter strap ring of the pair of strap rings is provided at approximately the center of any adjacent vane, and the antenna lead is connected to the connecting point of the strap ring. It has a structure that extends in the axial direction of the cylindrical tube and reaches the output antenna section.

Operation With the above configuration, the antenna lead is connected to the two vanes via the strap ring, which substantially increases the extension length in the high density space of microwave energy in the small resonant cavity of the antenna lead. Since the coupling with wave energy can be increased, unnecessary radiation can be suppressed while producing high 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 arranged in the anode cylinder, 40 is a vane] 1.11
A pair of strap rings with different diameters are disposed on the same plane approximately in the center of the polar cylinder tube axis and are connected alternately to a plurality of vanes, 42 is an antenna lead, and one end is connected to a plurality of vanes. (11) Adjacent vanes are connected to a large-diameter strap ring 40 at approximately the center thereof, and from this connection point to a coupling hole 44 provided in a pole piece 43 attached from the anode cylindrical end surface is positive (j
An output antenna section is arranged approximately parallel to the axial direction of the cylindrical tube, has an appropriate bent part 45 in front of the coupling hole 44, and after passing through the coupling hole 44, is again provided with an appropriate bent part, and is arranged in the axial direction of the anode cylindrical tube. It is made to extend concentrically inside the exhaust pipe 47 which is a component of 46. 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.

48 is a pole piece attached from the other end of the anode cylinder;
Reference numeral 9 denotes an antenna side tube, 50 a measuring tube made of a ceramic material and a one-groove one-hole part of the output antenna portion, and 51 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. Furthermore, since the antenna lead is arranged in a high-density electric field space via the strap ring, the coupling with microwave energy can be sufficiently increased, and high output efficiency can be obtained.

In addition, since the antenna lead from the coupling hole of the pole piece to the strap ring is arranged in the axial direction of the anode cylindrical tube, the antenna lead can be easily mounted on the strap ring, and at least two bent parts can be attached to the antenna lead. By providing this, the antenna lead absorbs the change in volume of the antenna lead when it is cut integrally with the exhaust pipe, so that deformation of the strap ring caused by the antenna lead being pushed toward the anode cylinder side can be prevented.

Note that the shape of the antenna lead may be either round or plate-shaped, but if it is a round bar, it is better to have at least one bent part shaped into a plate so that the stress on the strap ring during cutting can be easily absorbed by the antenna lead. That is clear.

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

(1) By directly connecting the antenna lead to the stranding arranged in the high-density electric field space inside the vane, it is possible to suppress unnecessary radiation while achieving high output efficiency.

(2) Since the antenna lead is provided with at least two bent portions, the stress generated when cutting the exhaust pipe can be sufficiently absorbed by the antenna lead, preventing deformation of the strap ring, and providing a highly reliable magnetron. .

(3) By arranging the antenna lead from the coupling hole of the hole piece to the strap ring in the axial direction of the anode cylinder tube, the antenna lead and the strap ring can be easily connected and assembled.

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

[Brief explanation of the drawing]

4 is a sectional view of a conventional magnetron, FIG. 4 is an electric field distribution diagram in a conventional anode groove body, and FIG. 5 is an electric field distribution diagram in a positive magnetron structure of the present invention. 38... Anode cylinder, 39... Vane, 40
...Large diameter strap ring, 41...
・Small diameter strap ring, 42...Antenna lead, 43.48...Pole piece, 44.
...Coupling hole, 46...Output antenna part. Name of agent: Patent attorney Masao Nakao, 1st person
Figure 2 Figure 3 Figure 3/'

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 a pair of strap rings arranged from both end surfaces of the anode cylinder. A pole piece, an output antenna portion disposed in the axial direction of the anode cylindrical tube, and one end connected to the large diameter strap ring of the strap ring and extending from this connection point in the axial direction of the anode cylindrical tube to connect the pole piece. and an antenna lead provided in the piece, passing through the coupling hole and having the other end extending to the output antenna section.