JP2001084917A - High-frequency heating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently restrain unwanted radiation waves leaking from an input part of a magnetron to the outside of a shield case. SOLUTION: This device is provided with a shield case 6 for surrounding an input part 10 of a magnetron 1 and having a metallic lid 7, a feed-through capacitor 14 penetrating through the shield case 6, a lead wire 16 connected to the feed-through capacitor 14, an input terminal 8 fixed on the tip of the lead wire 16 in order to supply high-voltage current, and a conductive spiral cylinder 18 for coaxially surrounding the lead wire between the input terminal 8 and the feed-through capacitor 14 via an insulative lead wire cover 17. This spiral cylinder 18 is fixed to a metallic cover 9 surrounding the feed-through capacitor 14, the metallic cover 9 is fixed to a shield case 6, a transmission mode of a coaxial path cannot be formed between the lead wire 16 and the spiral cylinder 18, and unwanted radiation waves are efficiently restrained from leaking to the outside of the metallic cover 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in means for suppressing unnecessary radiation waves leaking from an input section of a magnetron in a high-frequency heating device.

[0002]

2. Description of the Related Art In a conventional high-frequency heating device, in order to suppress unnecessary radiation waves leaking from an input portion of a magnetron, the input portion is surrounded by a metal shield case, and an input terminal protruding outside the shield case is provided. An LC filter composed of a choke coil containing ferrite and a feedthrough capacitor is provided between the input portions.

In this feedthrough capacitor, a straight through lead wire is passed through a through hole provided in a shield case via an insulating material.

[0004]

In the above-described LC filter, a coaxial line is formed between the through hole of the shield case and the through lead, and an unnecessary radiation wave of several tens MHz or more, which is easily radiated from the through lead to the space. Therefore, there is a problem that it is sometimes difficult to sufficiently suppress unnecessary radiation waves depending on a load condition of the high-frequency heating device or the like.

[0005]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a shield case with a metal lid surrounding a magnetron input section for generating high-frequency energy to be supplied to a heating chamber. A ferrite choke coil connected to the input part in the shield case, a feedthrough capacitor connected to the choke coil and penetrating the shield case, a lead wire connected to the feedthrough capacitor, and a An input terminal fixed to the tip of the lead wire, and a conductive spiral tube surrounding the lead wire between the input terminal and the feedthrough capacitor coaxially via an insulating lead wire cover,
This spiral tube is fixed to a metal cover surrounding the through capacitor, and the metal cover is fixed to the shield case, so that electromagnetic waves that have entered the metal cover through the through capacitor and the lead wire are fixed. An object of the present invention is to prevent a transmission mode of a coaxial line from being formed between helical cylinders, thereby efficiently suppressing unnecessary radiation waves that leak to the outside of a metal cover.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a shield case with a metal lid surrounding an input portion of a magnetron for generating high-frequency energy to be supplied to a heating chamber, and a ferrite choke connected to the input portion in the shield case. A coil, a feedthrough capacitor connected to the choke coil and passing through the shield case, a lead wire connected to the feedthrough capacitor, an input terminal fixed to the end of the lead wire for supplying a high voltage current, A conductive helical tube surrounding the lead wire between the input terminal and the feedthrough capacitor coaxially via an insulating lead cover, and a metal cover surrounding the helical tube around the feedthrough capacitor And the metal cover is fixed to the shield case.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS.

FIG. 1 shows a high-frequency heating apparatus according to an embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a main body of a magnetron that generates high-frequency energy, and 1a denotes a magnetron output antenna that protrudes into the waveguide 2 and is coaxially coupled. Reference numeral 4 denotes a high-frequency radiation port on the connection surface between the heating chamber 3 and the waveguide 2. Reference numeral 5 denotes an object to be heated such as food. 6 and 7 are components of the magnetron, 6 is a metal shield case, and 7 is a lid of the shield case 6. Reference numeral 8 denotes an input terminal for supplying a high-voltage current to the magnetron 1 from an external high-voltage power supply (not shown). A conductive spiral cylinder 18 coaxially surrounding the lead wire 16 fixed to the input terminal 8 via an insulating lead wire cover 17 forms a shield case 6.
Is attached to a metal cover 9 fixed to the cover. 9a
Is a ventilation hole provided in the metal cover 9.

FIG. 2 is a sectional view of a main part of the magnetron 1 as viewed from the direction of arrow A in FIG.

In FIG. 2, reference numeral 10 denotes an input unit for supplying power to a filament (not shown) of the magnetron 1. Reference numeral 11 denotes a support portion made of an insulating material for supporting the input unit 10. Reference numeral 12 is a choke coil containing ferrite. Reference numeral 13 denotes a through lead wire having one end protruding from the through capacitor 14 into the shield case 6. The choke coil 12 and the feedthrough capacitor 14 form an LC filter. The other end of the through lead 13 is connected to a lead 1 extending from the through capacitor 14 outside the shield case 6.
The input terminal 8 is fixed to the terminal of the lead wire 16.

The metal cover 9 surrounds the feedthrough capacitor 14 and confines the electromagnetic waves passing through the feedthrough capacitor 14.

The lead 16 to which the input terminal 8 is attached
Is drawn out of the cover 9 through the inside of the spiral tube 18 from the inside of the metal cover 9, and then the metal cover 9 is screwed to the shield case 6. 19 is a screw for that purpose. 1b is a flange for attaching the magnetron 1 to the waveguide 2, and 1c is a hole for passing an attachment screw (not shown).

FIG. 3 is an enlarged view of the vicinity of the spiral cylinder 18 surrounded by a dotted line in FIG. Numeral 20 denotes an incident electromagnetic wave which goes into the spiral tube 18 to leak to the outside along the lead wire 16. The lead wire 16 is an inner conductor, the spiral tube 1
Assuming a coaxial line with 8 as an external conductor, the directions of the magnetic fields surrounding the lead wire 16 are 21a and 21b, and the surface current induced by the magnetic field to flow on the inner surface of the spiral tube 18 is 22; The electric field between the lead 16 and the helical tube 18 is shown at 23. These directions of the magnetic field, the surface current, and the electric field are transmission modes when the incident electromagnetic wave 20 leaks outside through the space between the lead wire 16 and the spiral tube 18.

However, the surface current 22 cannot flow in the direction indicated by the dotted arrow due to the gap 18a in the spiral tube 18.

Therefore, the amount of the electromagnetic wave 24 leaking out of the incident electromagnetic wave 20 is extremely small. That is, unnecessary radiation waves leaking from the input unit 10 of the magnetron 1 to the outside through the feedthrough capacitor 14 attached through the shield case 6 can be efficiently suppressed.

In order to efficiently and smoothly insert the input terminal 8 of the terminal of the lead wire 16 into the spiral tube 18, the cross-sectional shape of the spiral tube 18 corresponds to that of the connection terminal 15. Is desirable.

FIGS. 4, 5 and 6 show the shape or cross section of a surface perpendicular to the central axis of the helical cylinder 18 as viewed from the direction of arrow B in FIG. 3, respectively. FIG.
Is an ellipse, and FIG. 6 is a rectangle.

In any of these shapes shown in FIGS. 4 to 6, since the area of the gap between the lead wire 16 and the helical tube 18 is sufficiently small, it goes without saying that unnecessary radiation can be sufficiently suppressed.

[0020]

As described above, according to the present invention,
A shield case with a metal lid surrounding the input part of the magnetron for generating high-frequency energy to be supplied to the heating chamber, a ferrite choke coil connected to the input part in the shield case, A feedthrough capacitor penetrating the shield case, a lead wire connected to the feedthrough capacitor, an input terminal fixed to the end of the lead wire for supplying a high voltage current, and a lead wire between the input terminal and the feedthrough capacitor And a conductive spiral tube surrounding the through-hole capacitor in a coaxial manner via an insulating lead wire cover, and the spiral tube was fixed to a metal cover surrounding the feedthrough capacitor, and the metal cover was fixed to a shield case. In this way, the lead wire spirals into the metal cover through the feedthrough capacitor. As it is impossible to form a transmission mode of the coaxial line between the suppress efficiently unnecessary radiation wave to be leaked to the outside of the metal cover.

That is, unnecessary radiation waves leaking from the input section of the magnetron to the outside through the feedthrough capacitor attached through the shield case can be efficiently suppressed.

Further, in a case where the input terminal is passed through the spiral tube while the connection terminal is fixed to the lead wire, the shape of the spiral tube can be made elliptical or rectangular.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a configuration of an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a principal part when the magnetron of FIG. 1 is viewed from the direction of arrow A.

FIG. 3 is an enlarged view of a portion surrounded by a dotted line in FIG. 2;

FIG. 4 is a diagram illustrating an example of a shape when FIG. 3 is viewed from a direction of an arrow B;

FIG. 5 is a diagram illustrating an example of a shape when FIG. 3 is viewed from a direction of an arrow B;

FIG. 6 is a diagram showing an example of the shape when FIG. 3 is viewed from the direction of arrow B.

[Explanation of symbols]

1: magnetron, 3: heating room, 6: shield case,
7: lid, 8: input terminal, 9: metal cover, 10: input section, 12: choke coil, 14: feedthrough capacitor, 1
6: lead wire, 17: lead wire cover, 18: spiral tube.

Claims (1)

[Claims] 1. A shield case (6) with a metal lid (7) surrounding an input part (10) of a magnetron (1) for generating high-frequency energy to be supplied into a heating chamber (3).
A ferrite choke coil (12) connected to the input section (10) in the shield case (6); and a feedthrough capacitor (14) connected to the choke coil (12) and passing through the shield case (6). ), A lead wire (16) connected to the feedthrough capacitor (14), an input terminal (8) fixed to the end of the lead wire (16) to supply a high voltage current, and the input terminal (8). And the lead wire (16) between the capacitor and the feedthrough capacitor (14).
And a conductive helical tube (18) surrounding the through-condenser (14) coaxially with an insulating lead wire cover (17). The metal cover (18) surrounds the helical tube (18). 9) A high-frequency heating apparatus, wherein the metal cover (9) is fixed to the shield case (6).