JP2001084916A - High-frequency heating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently restrain undesired radiation waves which leak from the input part of a magnetron to the outside of a shield case. SOLUTION: This device is provided with a connecting terminal 15 to be connected detachably to an input terminal 8 projecting from a feed-through capacitor 14 formed on an input part 10 of a magnetron 1, a lead wire 16 fixed to the connecting terminal 15 and for supplying high-voltage current from the outside, and a conductive spiral cylinder 18 for partially and coaxially surrounding the lead wire 16 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 input terminal 8 and the connecting terminal 15, 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 in relation to electromagnetic waves which entered the metallic cover 9 through the feed-through capacitor 14, and unwanted radiation waves to be leaked to the outside of the metallic cover 9 is restrained efficiently.

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 this choke coil and penetrating the shield case, an input terminal protruding from the feedthrough capacitor, and detachably connected to this input terminal A connection terminal to be connected, a lead wire fixed to the connection terminal to supply a high-voltage current from the outside, and a conductive spiral tube surrounding a part of the lead wire coaxially through an insulating lead cover. Is fixed to a metal cover surrounding the feedthrough capacitor, the input terminal, and the connection terminal. The electromagnetic wave intruding into the metal cover through the feedthrough capacitor by being fixed to the above shield case, so that the transmission mode of the coaxial line cannot be formed between the lead wire and the spiral tube, This is to efficiently suppress unnecessary radiation waves that are to leak to the outside of the metal cover.

[0006]

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a shield case with a metal lid surrounding an input part of a magnetron for generating high-frequency energy to be supplied to a heating chamber, and a ferrite-containing choke connected to the input part in the shield case. A coil, a through-capacitor connected to the choke coil and penetrating the shield case, an input terminal protruding from the through-capacitor, a connection terminal detachably connected to the input terminal, and fixed to the connection terminal. A lead wire for supplying a high-voltage current from the outside, and a conductive spiral tube surrounding a part of the lead wire coaxially through an insulating lead wire cover are provided. The input terminal and the connection terminal are fixed to a metal cover surrounding the connection terminal, and the metal cover is fixed to the shield case. That.

[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 for generating high-frequency energy, and 1a denotes a magnetron output antenna projecting into the waveguide 2 and 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 16 denotes a lead wire for supplying a high-voltage current from an external high-voltage power supply (not shown) to the magnetron 1. A conductive helical tube 18 is provided to coaxially surround a part of the lead wire 16 via an insulating lead cover 17. The spiral tube 18 is attached to a metal cover 9 fixed to the shield case 6. 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 is a through lead wire protruding from the through capacitor. Choke coil 12 and feedthrough capacitor 1
4 forms an LC filter. Through lead wire 13
Is connected to the input terminal 8. Reference numeral 15 denotes a connection terminal fixed to the lead wire 16 and detachably connected to the input terminal 8 on the feedthrough capacitor 14 side. This connection terminal 1
The lead wire 16 to which the wire 5 is attached passes through the spiral tube 18 from outside the metal cover 9 and is incorporated into the cover 9. After connecting the connection terminal 15 to the input terminal 8, the metal cover 9 is shielded. It can be attached to the case 6. The metal cover 9 surrounds the feedthrough capacitor 14, the input terminal 8, and the connection terminal 15, and is for confining electromagnetic waves passing through the feedthrough capacitor 14. Reference numeral 19 denotes a screw for fixing the metal cover 9 to the outside of the shield case 6. 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 of the dotted arrow due to the gap 18a in the spiral tube 18.

Therefore, the amount of the electromagnetic wave 24 leaking to the outside of the incident electromagnetic wave 20 is extremely small. That is, unnecessary radiation waves leaking from the input section 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 connection terminal 15 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 of the surface of the spiral cylinder 18 in a direction perpendicular to the central axis of the spiral cylinder 18 as seen from the direction of arrow B in FIG. 3, that is, the sectional shape. ,
FIG. 5 shows an elliptical shape, and FIG. 6 shows a rectangular shape.

In any of the 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.

[0018]

As described above, according to the present invention,
A shield case with a metal lid surrounding the input portion of the magnetron for generating high-frequency energy to be supplied into the heating chamber, a ferrite choke coil connected to the input portion in the shield case, A feedthrough capacitor penetrating the shield case, an input terminal protruding from the feedthrough capacitor, a connection terminal detachably connected to the input terminal, and a lead wire fixed to the connection terminal and supplying a high-voltage current from outside;
A conductive helical tube surrounding a part of the lead wire coaxially through an insulating lead wire cover is provided, and the helical tube is made of metal surrounding the feedthrough capacitor, the input terminal, and the connection terminal. By fixing the metal cover to the shield case, the transmission mode of the coaxial line between the lead wire and the helical cylinder against electromagnetic waves penetrating into the metal cover through the feedthrough capacitor. Is not formed, and unnecessary radiation waves that are leaking to the outside of the metal cover are 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 main parts 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
5: connection terminal, 16: 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). ), An input terminal (8) protruding from the feedthrough capacitor (14), and a connection terminal (1) detachably connected to the input terminal (8).
5), a lead wire (16) fixed to the connection terminal (15) and supplying a high-voltage current from the outside, and a lead wire (1).
A conductive helical cylinder (18) surrounding a part of 6) coaxially via an insulating lead cover (17);
This spiral tube (18) is connected to the feedthrough capacitor (14),
A high-frequency heating device fixed to a metal cover (9) surrounding the input terminal (8) and the connection terminal (15), and the metal cover (9) fixed to the shield case (6). .