JPS61190834A - Magnetron for microwave oven - Google Patents

Abstract

PURPOSE:To reduce spuriousness in the body of a magnetron, by holding cathode input lines and cathode supports separately on a ceramic stem, and connecting the lines and the supports to each other through inductors provided on the vacuum side of the stem. CONSTITUTION:A cathode 3 made of a thorium-tungsten filament is secured with an end chip 20 and end flanges 21, 22 to cathode supports 23, 24 made of molybdenum or the like, in the center of an anode cylinder 1, so that a magnetron is constructed. Cathode input lines 25, 26 hermetically penetrate a ceramic stem 19 provided at an input portion 50. Choke coils 32, 33 effective for reduction of leak are connected to the vacuum-side ends of the cathode input lines 25, 26 from the cathode 3, and connected to the supports 23, 24 through coupling metal members 27, 28, 34, 35 on the inside surface of the stem 19. As a result, the deterioration of hermetically coupled portions is reduced, and an external filter is made simple and compact.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a magnetron for an electron lens, and particularly to an improvement in the structure of its cathode support structure.

[Background technology and its problems]

A cathode support structure in a conventional microwave oven magnetron is constructed as shown in FIG. 4, in which both ends of a spirally wound cathode 400 are fixed to a pair of end hats 41 and 42, either directly or via an end chip F43. There is. And, in both ends, 41 and 42, Moripfun (
A pair of cathode support rods 44 and 45 made of Mo) are fixed. These cathode support rods 44, 45 pass through respective through holes 47, 48 of the ceramic stem 46 and are hermetically fixed to terminals 49, 51 which are hermetically soldered to their outer surfaces. Reference numerals 52 and 53 represent the soldered portions. Further, a metal container 54 , which constitutes a part of the vacuum container, is hermetically connected to the upper end surface of the ceramic stem 46 at a soldered portion 55 .

However, in such a conventional structure, molybdenum (Mo
A pair of cathode support rods 44 and 45 made of
Since the cathode is hermetically sealed at the lower end face and extended to the outside, it needs to be quite long, the parts cost is relatively high, and it is difficult to obtain sufficient cathode support strength. Also, the difference between Mo material and Copal (product name) terminal 49.51! ! F1jk bonding is difficult, and the airtight solder joint becomes high in temperature due to conduction heat from the cathode 40, making it difficult to obtain high reliability of this joint.

On the other hand, the structure shown in FIG.
This is proposed in newsletter No. 747, etc.

This consists of a ceramic stem 46 and each cathode support rod 44.45
The structure is such that the hermetic joint with the cathode stem 46 is hermetically brazed using bonding rings 56 and 57 on the cathode 40 side of the cathode stem 46, that is, on the side facing the vacuum region. In that case, a step is provided between the soldered portion 55 between the ceramic stem 46 and the metal container 54 and the soldered portions 52 and 53 between the ceramic stem 46 and the cathode support rods 44 and 45, so that the gap between them is The withstand voltage performance is improved. However, even with this structure, Mo
The cathode support rods 44, 45 manufactured by the manufacturer must be made longer, which is still costly, and the soldered portions of the cathode support rods 44, 45! There is a disadvantage that heating of 52.53 is unavoidable. Furthermore, in any of the examples, the ceramic stem 4
6, the cathode support rods 44, 45, and the metal container 54 are located at different positions in the tube axis direction, which disadvantageously complicates the process of forming a metallized layer for soldering them.

[Purpose of the invention]

An object of the present invention is to provide a magnetron for a microwave oven that has a small number of parts, has a filter effect, and has significantly improved reliability and workability.

[Summary of the invention]

In order to achieve the above object, the present invention provides an electron input line in which a cathode input line and a cathode support are separated, and both are connected in a gaseous manner to an inductor placed on the vacuum side of a ceramic stem. This is a microwave magnetron.

[Embodiments of the invention]

The magnetron of this invention is constructed as shown in FIGS. 1 to 3, with FIG. 2 showing an enlarged view of the main part of FIG. 1, and FIG. 3 showing the vicinity of the ceramic stem 19 taken out. It is something that

That is, on the inner surface of the steel anode cylinder 1, a plurality of copper vanes 2 are arranged radially toward the center. At the center of the anode cylinder 1, there is disposed a cathode 3 made of a spirally carbonized trichum tungsten filament, and each end of the cathode 3 has an end tip 20,
It is fixed to the end hat 22. This end tip 20. The end hat 21 is attached to a rod-shaped cathode support 23, and the end hat 22 is attached and swung to a rod-shaped cathode support 24. These cathode supports 23, 24 are made of a high melting point metal such as molybdenum. Further, a radiator 6 consisting of a plurality of aluminum fins is fixed to the outer periphery of the anode cylinder 1. Further, iron pole pieces 4.5 are fixed to both ends of the anode cylinder 1, respectively, and annular ferrite magnets 7, 8 are arranged on the outside of each pole piece 4.5 in the tube axis direction. . A ferromagnetic yoke 29 is provided to surround the anode cylinder 1, radiator 6, and ferrite magnet 7.8, and is attached to the ferrite magnet 7.8. An output portion 30 is protruded from one of the pole pieces 5, and this output portion 30 includes a cylindrical sealed metal body 14, a ceramic cylinder 15, a sealed metal body 16, an exhaust pipe 17, an end cap 31,
It consists of an antenna feeder 13, and this antenna feeder 13 is connected to one of the panes 2. Further, an input section 50 is provided on the other sol piece 4 in a protruding manner. That is, a ceramic stem 19 projects through the ferrite magnet 7 via a metal sealing body 18 made of a thin iron plate with a thickness of 0.4 m. This ceramic stem 19 has a recess V formed on its outer surface on the atmosphere side, and two through holes H1H and I, respectively, are formed in the tube axis direction, and cathode input lines 25. 26 is penetrated. Further, on the vacuum side inner surface of the ceramic stem 19, an annular metallized surface S1 is formed on the outside (periphery), and a metallized surface S divided into four parts is formed on the inside.
, IS, ,S4 ,S, is formed. The metal sealing body 1 is provided on the annular metallized surface S1.
B is the metallized surface divided into four parts S, , S, , S,
, s, have joint metal bodies 27°2B and 34.35 hermetically sealed by silver brazing, respectively. The above bonded metal bodies 2'l, 2B.

34.35 is made into a plate shape and made of an iron-nickel alloy with a coefficient of thermal expansion close to that of ceramic, and the bonded metal body 27.2
8 covers the through holes H, H, respectively, and each joining metal body 27! , 2g, one end of the cathode input line 25, 26 passes through each of the cathode input lines 25, 2g and is fixed in a vacuum-tight manner. The other ends of the cathode input lines 25 and 26 are connected to feedthrough capacitors 10 and 11 fixed to the shield deck 9, respectively.

In addition, Shield GEX 9 has the above ceramic stem 19.
and is attached to the yoke 29, covering a part of the feedthrough capacitor 10.11. Further, the bonded metal body 34
35, cathode supports 23 and 24 are respectively passed through and fixed in a vacuum-tight manner. And the joining metal bodies 21, 34
Both ends of an inductor, such as a choke coil 320, are connected to each of the protrusions 27a and 34aK. Further, both ends of an inductor, such as a choke coil 33, are connected to each of the protrusions 28m and 35m of the metal body 28°350. In this invention, the cathode input line 25, 26 and the cathode support 23, 24 are separated, and are electrically connected via choke coils 32 and 33, respectively. In this case, as is clear from the figure, each choke coil 32, 33 is located on the vacuum side of the ceramic stem 19, and is a noise suppressing choke coil formed of, for example, a coiled copper wire. It also serves as a path for cathode current and anode current. and cathode input line 25.
26, choke coils 32, 33, joining metal body 27.
2B.

34.35, cathode support 23.2'4, entoch, f2
0, and is electrically connected to the cathode 3 via an end hat 21 and an end hat 22.

The present invention can also be applied to a structure in which the through-hole of the stem is hermetically sealed on the inner surface on the vacuum side only by a joining metal body, and the cathode input line is electrically connected to the back surface of the joining metal body on the atmosphere side.

〔Effect of the invention〕

According to the invention, the cathode input lines 25, 26 and the cathode support 23. 24, an element (chi) that affects the fundamental wave, harmonics, line noise, etc. and is effective in reducing leakage from the cathode 3 side.

- Kucoil 32.33)'lk, can be inserted. As a result, spurious noise can be reduced in the magnetron main body, and the external filter can be easily constructed or downsized. Further, since heat conduction from the cathode support to the joining metal body and the cathode input line is suppressed, deterioration of the airtight joint is reduced.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing a microwave oven magnet according to an embodiment of the present invention, FIG. 2 is a cross-sectional view showing an enlarged main part of FIG. 1, and FIG. The sectional view showing the vicinity of the ceramic stem, and FIGS. 4 and 5, are sectional views showing a conventional magnetron for a microwave oven. DESCRIPTION OF SYMBOLS 1... Anode cylinder, 3... Cathode, 19... Ceramic stem, 23.24... Cathode support, 25.26.
...Cathode input line, 21,211,34.35...Joining metal body, 321.33...Inductor (choke),
H, H...through hole, ■...recess. Applicant's agent Patent attorney Takehiko Suzue Figure 2 Figure 3

Claims (2)

[Claims] (1) A ceramic stem is hermetically sealed and protrudes from one open end of the anode cylinder, and the ceramic stem is penetrated through a through hole formed in the ceramic stem and connected to the inner surface of the ceramic stem on the vacuum side via a bonded metal body. a hermetically sealed cathode input line;
In a microwave oven magnetron comprising a rod-shaped cathode support disposed along the axis of the positive and negative cylinders and supporting a cathode, the cathode input line and the cathode support are separated,
A magnetron for a microwave oven, characterized in that both are electrically connected via an inductor placed on the vacuum side of the ceramic stem. (2) The magnetron for a microwave oven according to claim 1, wherein the inductor is electrically connected to a part of the bonded metal body.