JPH0746634B2 - Magnetron - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a magnetron provided with a filter device,
In particular, the present invention relates to a structure of a magnetron filter device suitable for a microwave oven using a high frequency drive power source.

[Background of the Invention]

FIG. 1 shows a conceptual diagram of the structure of a power supply for driving the magnetron. In FIG. 1, reference numeral 1 is a commercial power supply of 50 to 60 Hz, which generates a cathode current and a high voltage supplied to a magnetron 3 by a transformer 2. 4 is a smoothing capacitor, and 5
Is a rectifying diode. A part surrounded by a dotted line 6 is a magnetron 3 which is normally configured at present, and a part surrounded by a dotted line 7 is a filter device unit integrally attached to the magnetron 3, which is an inductance component by a chiyoke coil 8 and a part 9 The feedthrough capacitor is used to eliminate unnecessary radio waves (mainly TV noise) generated in the magnetron 3.

Recently, the so-called inverter power supply, which converts a commercial power supply into a high frequency of 10K to 100KHz, and thereby makes the transformer significantly smaller, is being developed and put into practical use.

FIG. 2 shows a conventional magnetron filter device having a conventional structure. A filter case 16 shaped into a box with a bottom is forcibly inserted into the seal cylinder 10 of the tube body of the magnetron, and the cathode in the tube is attached to the stem ceramic 11 which is vacuum-sealed in the seal cylinder and silver-brazed. Two supporting leads 12 pass through the stem ceramic together with the terminal 13 and are vacuum-tight and brazed with silver.
Each of the terminals 13 has a yoke coil 8 centered on a ferrite core fixed thereto, and the other end thereof has a feedthrough capacitor 9
It is connected to the. The feedthrough capacitor 9 is fixed to the filter case 16 via a chassis plate 9a having a ground potential. Further, a lid 17 is caulked and fixed to the filter case 16 at its four sides to shield higher harmonics and the like which are unnecessary radio waves of the magnetron. The above configuration corresponds to the portion surrounded by the dotted line 7 in FIG. Filter case 16 here
Since the cathode current supplied to the terminal 12 of the cathode inside is a relatively large current of 10 to 16 A in an ordinary magnetron, φ1.0 to 1.6
Thick wire rod is required. Further, if an attempt is made to include a transformer for supplying a cathode current in the filter case 16, the commercial power supply (50 or 60 Hz) has a low frequency, and therefore the transformer itself becomes large, which is not a good idea.

[Object of the Invention]

An object of the present invention is to provide a magnetron suitable only for driving with an inverter power supply that converts a commercial frequency power supply into a high frequency.

[Outline of Invention]

A magnetron that incorporates a heater transformer in the filter case, taking advantage of the small size of the transformer used for the inverter power supply.

Example of Invention

An embodiment of the present invention will be described below with reference to FIG. 16 is a tube seal 10 of the magnetron 3 as in the case of FIG.
A box-shaped plastic case or ceramics in which the lead-in wire 21 that also serves as the winding on the primary side of the transformer that supplies the cathode current has the core 22 of the transformer inside. Insulation box 23
Penetrates through the bottom of the. The penetrating portion is the insulating box 23.
The tubular portion 23a integrally formed with the above is fitted and fixed in the through hole of the side wall of the filter case 16. Insulation box
The core 23, which is a rectangular or circular (rectangular in FIG. 3) magnetic core, is wound with a secondary winding 24 and is connected to the terminal 13 connected to the cathode by arc welding or the like.
Here, the core 22 is made of ferrite with less high-frequency loss, but since the insulation is inferior to that of plastics, the winding portion of the lead wire 21 and the secondary winding 24 is made of an insulating sheet.
25 is preferably used as a base. Insulation box 23
The components inside are stored with almost no gap around the core 22, and since the secondary winding 24 uses a relatively thick wire rod, the movement against vibration can be suppressed considerably, but the insulation is improved. Therefore, when molded and fixed with the epoxy resin 26, it is easy to handle in a form integrated with the insulating box 23.

On the other hand, in order to supply a high voltage, one lead wire 27a of the inductance element 27 is connected to one end of the secondary winding, and the other lead wire 27b is connected to the feedthrough capacitor 28. Soldering is generally sufficient for this connection method,
Since the current flowing through the lead wires 27a and 27b of the inductance element 27 is 200 to 400 mA at the most, it can be a fine wire with a diameter of 0.5 or less. Therefore, winding using a wrapping tool as shown in FIG. . Alternatively, the lead wires 27a, 27b may be made of iron, nickel, or an alloy thereof, and one may be fixed to the cathode terminal and the other to the center conductor of the feedthrough capacitor 28 by spot welding. Further, the feedthrough capacitor 28 has a chassis plate 28a fixed to the filter case 16, which has a ground potential, like the double feedthrough capacitor shown in FIG. In the example of FIG. 3, the insulating box 23 and the feedthrough capacitor 28 are respectively provided in the filter case 16
It is mounted on the surface opposite to the side surface of 180 °, but may be fixed on the surface facing 90 ° or on the same surface for convenience of external wiring.

Next, regarding the fixing of the insulating box 23, as shown in FIG. Alternatively, they may be simply fixed with an adhesive material. Further, as shown in the partial view of FIG. 4, the through hole provided in the filter case 16 is burred to form a cylindrical portion 16a, and the cylindrical portion 2 of the insulating box 23
By inserting 3a, the function of blocking the electric wave leaking from this portion is improved. Further, as shown in FIG. 5, a metallic bush 30 having a separately formed hat portion can be fitted into the cylindrical portion 23a to further improve the radio wave leakage prevention function as compared with the example of FIG. I can.

〔The invention's effect〕

According to the present invention, in a magnetron driven by a high frequency power supply, a transformer for supplying a cathode current can be housed in a filter case in a highly insulating state, a radio wave leakage prevention function is improved, and a filter device with good assemblability is provided. It has an effect that it can be configured with high reliability.

[Brief description of drawings]

FIG. 1 is a diagram showing a basic circuit configuration of a magnetron drive power source, FIG. 2 is a diagram showing a conventional magnetron filter device, and FIG. 3 is a diagram showing an embodiment showing a magnetron filter device according to the present invention. 4 and 5 are views showing another embodiment of the portion for fixing the insulating box. 2 ... Transformer, 3 ... Magnetron, 13 ... Cathode terminal, 16 ... Filter case, 21 ... Lead wire, 22 ... Core, 23 ... Insulation box, 23a ... Cylindrical part, 24 ... Two Next winding, 2
7 ... Inductance element, 27a, b ... Lead wire, 28 ...
Feedthrough capacitor.

Claims (8)

[Claims] 1. A bottomed box type filter case fitted and fixed to the cathode input side of a magnetron tube driven by an inverter power supply, and a lid body having four sides crimped and fixed to the open side of the filter case. In a magnetron equipped with a filter device, a feedthrough capacitor for supplying a high voltage through its central conductor and a heater transformer for supplying a heater current whose outside is covered with an insulating box are fixed to the side surface of the filter case. The heater transformer is fixed inside the filter case through the insulating box, the feedthrough capacitor is connected to one of the cathode terminals of the magnetron body through an inductance element, and the secondary side of the transformer is the cathode. A magnetron having a filter device connected to a terminal. 2. The insulating box including the transformer is integrally formed with a lead-in wire for conducting a cathode current and a cylindrical portion on a surface abutting on the filter case, and a through hole provided in the filter case. The magnetron according to claim 1, which is fitted in the hole. 3. The magnetron according to claim 1, wherein the through hole of the filter case into which the cylindrical portion of the insulating box is fitted has a cylindrical portion formed by burring. 4. A metal bush having a tubular portion surrounding the tubular portion and a hat portion abutting on the filter case, in a through hole of a filter case into which the tubular portion of the insulating box is fitted. The magnetron according to claim 1, which is inserted. 5. The magnetron according to claim 1, wherein the tubular portion of the insulating box is inserted into the filter case, and the protruding portion is covered and fixed with a heat-shrinkable tube together with a cathode current introduction line. . 6. The magnetron according to claim 1, wherein the transformer contained in the insulating box is molded and fixed with a resin. 7. A lead wire of the inductance element, wherein one of the lead wires is wound around one of the secondary windings of the transformer and the other is wound around the center conductor of the feedthrough capacitor (wrapping). The magnetron according to item 1. 8. The lead wire of the inductance element is iron,
2. The magnetron according to claim 1, wherein nickel or an alloy thereof is spot welded to one of the cathode terminals and the other to the center conductor of the feedthrough capacitor.