JPS59941B2 - magnetron device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates primarily to improvements in magnetrons used in microwave ovens.

Conventional microwave oven magnetrons consist of a cathode that emits electrons, an anode cylinder located around the cathode to form a cavity, multiple vanes fixed to the inner wall of the anode cylinder, and placed at both ends of the anode cylinder. A permanent magnet placed outside the anode cylinder supplies a magnetic field through the magnetic poles to the working space surrounded by the vanes.

In contrast to such a conventional magnetron, permanent magnets 1a and 1b are arranged inside an anode cylinder 5 as shown in FIG.
Small and inexpensive magnetrons are being put into practical use by increasing the efficiency of magnetic utilization.

In this type of magnetron in which the permanent magnets 1a and Ib are arranged inside the anode cylinder 5, the permanent magnet 1b is arranged close to the central axis of the anode cylinder 5.
It is not possible to provide the output antenna 4 on the central axis of the antenna.

Therefore, in the conventional magnetron of this kind, the anode cylinder 5 is placed at the center of the output antenna side of the yoke 8 which surrounds the heat sink 9 along the center of the heat sink 9, and the output antenna 4 is placed along the ventilation axis passing through the central axis of the anode cylinder. A structure as shown in FIG. 2, which is arranged on a line perpendicular to a-a', is adopted.

However, in a magnetron with such a structure, the relationship between the antenna 4 and the yoke 8 is asymmetrical, so when the magnetron is mounted through a waveguide or through the open screw holes 12 made at four locations on the yoke 8, , the tightening of the gasket part 10, which is provided concentrically with the output antenna 4, and the waveguide or open circuit becomes unbalanced, resulting in a partial contact failure, resulting in discharge, radio wave leakage, and even unnecessary radiation. There was a problem that leakage occurred.

Also, when mounting it on a waveguide, it is easier to tighten it on both sides of the waveguide 13 by making it symmetrical with respect to the ventilation axis, as shown in Fig. 3, due to the positional relationship. This is a reliable method.

However, in this case, since the output antenna 4 of the magnetron is located at a position far away from the central axis of the waveguide 13, it becomes difficult for the output antenna 4 to excite radio waves into the waveguide 13 without reflection.

This is because electromagnetism teaches that in order to most effectively excite radio waves within a waveguide, the output antenna 4 should be located at the maximum point of the electric field distribution of the radio waves propagating within the waveguide, that is, on the center line of the waveguide 13. This is because it must be located.

Therefore, the present invention solves the above-mentioned conventional drawbacks with a simple configuration.

Note that common parts in FIGS. 1 to 4 are designated by the same reference numerals.

That is, la and 1b are permanent magnets, 2 is a vane, 3 is a conductor connecting the vane 2 and the output antenna, 4 is the output antenna, 5 is an anode cylinder, 6 is a cathode lead that supports the cathode 7 and supplies voltage, and I is a cathode lead. A cathode that emits electrons, 8 a yoke that surrounds the heat sink 9 to form a ventilation path and a return magnetic path for the permanent magnet, and also serves as a supporting body for mounting the magnetron in an open manner; 9 a heat sink; 10 is a gasket that makes electrical contact between the magnetron anode and the waveguide etc. on which the magnetron is attached, 11 is a shield case that prevents radio wave leakage from the ceramic plate side, 12 is a screw hole for mounting, and 13 is a guide. Waveguide a/ is the ventilation axis and b is the electric field distribution within the waveguide.

In FIG. 4, in the magnetron, the central axes of the output antenna 4 and the anode cylinder 5 are located on the ventilation axis a-a', and the output antenna 4 is located approximately at the center of the cooling plate 9, and therefore approximately at the center of the yoke 8. , the anode cylinder 5 is located at a position offset from the center.

By adopting the above structure, the output antenna 4 and the gasket part 10 are located approximately at the center of the magnetron, so the tightening of the gasket part 10 is uniform when the magnetron is installed in a waveguide or in the open. The occurrence of electrical discharges due to defects, radio wave leakage, unnecessary radiation leakage, etc. can be greatly reduced.

Also, when installing the magnetron in the waveguide 13, if the magnetron is installed symmetrically, the output antenna 4 will be on the center line of the waveguide 13, so impedance matching will be easily achieved, and the radio waves emitted from the magnetron will be
It is possible to guide nearly 0% into the waveguide 13.

On the other hand, since the anode cylinder 5 is located at a position biased to one side on the ventilation axis a-a' with respect to the cooling plate 9, the air is cooled from the side (a side) nearer to the anode cylinder 5 of the two openings of the ventilation passage. When cooling air is sent into the ventilation passage by a fan, the anode cylinder 5 is moved to the cooling plate 9.
The effect of forcibly removing the air around the anode cylinder 5 is greater than when it is in the center of the anode cylinder.

Therefore, it has been experimentally confirmed that the cooling of the anode cylinder 5 of the magnetron is enhanced.

As described above, according to the present invention, the central axes of the anode cylinder and the output antenna are provided on a straight line with the ventilation axis, the antenna is provided in the center of the cooling plate, and the anode cylinder is provided on the entrance side of the ventilation path, so that the magnetron When installed, the tightening of the gasket around the antenna is stable, preventing electrical discharge, radio wave leakage,
Less leakage of unnecessary radiation.

Furthermore, the anode cylinder also has the effect of being well cooled.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of a conventional magnetron, Fig. 2 is a bottom view of the magnetron, Fig. 3 is a sectional view of the magnetron attached to a waveguide, and Fig. 4 is an embodiment of the present invention. FIG. 2 is a bottom view of the magnetron device. 1a, 1b...Permanent magnet, 2...Vane, 4...Output antenna, 5...Anode cylinder, 6...Cathode lead , 7... cathode, 8... yoke, 9... heat sink.

Claims (1)

[Claims] 1. A plurality of vanes, an anode cylinder, an output antenna connected to the vane by a conductor and not on a concentric axis with the anode cylinder, and an output antenna that is provided on a plane perpendicular to the central axis of the anode cylinder and has an outer periphery. a plurality of cooling plates each having a substantially rectangular shape;
a cooler having an air guide configuration with openings on two opposing long sides of the cooling plate to serve as entrances and exits of ventilation passages, the center axis of the anode cylinder and the output antenna being aligned with the ventilation axis of the cooler. The output antenna is arranged on a straight line, and the central axis of the anode cylinder is shifted from the center of the cooling plate, so that the output antenna is arranged approximately at the center of the cooling plate.