JPH0968314A - Electronic oven range - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a filter with a higher safety while lowering the leakage of a noise from a magnetron of an electronic oven range. SOLUTION: A ferrite ring 50 is formed in the perimeter of a metal gasket 18 linked to an anode piece of a magnetron 10 and an anode current flowing into a case body of the magnetron 10 from a cooking storage is supplied to the anode piece therethrough.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a microwave oven,
In particular, it relates to a technique for reducing the leakage of noise generated in the magnetron to the outside.

[0002]

2. Description of the Related Art Generally, a microwave oven uses a magnetron (high frequency oscillation tube) to generate a high frequency of about 2450 MHz, which is introduced into a cooking cabinet to heat food. However, the magnetron is not only for this useful frequency,
It also oscillates in a wide frequency range from 0 kHz to several tens of GHz. If radio waves having these frequencies leak to the outside of the microwave oven casing, they may interfere with other electronic devices (for example, radio interference) or cause malfunctions.

As a countermeasure against this, for example, JP-A-63-11
There is a technique described in Japanese Patent No. 6388. FIG. 4 is a peripheral circuit diagram of the magnetron in this conventional technique, FIG. 5 is a structural diagram of the magnetron in this conventional technique, (a) is a vertical partial sectional view, and (b) is a transverse sectional view. In FIG. 5, a high voltage is applied to the magnetron via the heater lead portion 11. The high voltage causes thermoelectrons to flow from the cathode heater 16 toward the anode piece (vane) 15. Two permanent magnets 14 are provided in the space between the cathode heater 16 and the anode piece 15.
Due to this, a magnetic field is applied, and the action of this magnetic field causes oscillation of microwaves. The anode piece 15 has an antenna 17
Is attached, and microwave energy is emitted from the antenna 17 into the air. Since the anode piece 15 is connected to the housing of the magnetron via the metal gasket 18, when the magnetron is attached to the microwave oven cooker, the anode current flows into the anode piece 15 through the cooker or ground.

Between the cathode heater 16 and the two heater leads 11, fixed K type low-pass filters each composed of a choke coil 13 and a feedthrough capacitor 12 are incorporated (see FIG. 4). This choke coil 13
Prevents the high frequency current from flowing out of the magnetron 10 as an inductive reactance, and the feedthrough capacitor 1
2 serves to release the noise current leaking from the heater lead wire to the ground. At this time, for example, the coil 13
Has an inductance of 1.5 μF, and the capacitor 12 has a capacitance of 500 pF.

However, since the noise suppression effect is not sufficient with the above filter alone, a power supply filter is generally additionally used. FIG. 6 is a schematic diagram of a magnetron oscillator circuit with a power filter added. AC100
A power supply filter 20 including a choke coil and a capacitor is provided at the entrance of the V power supply line, and the magnetron 1
The noise generated at 0 is suppressed from leaking to the outside of the microwave oven casing through the power supply line.

In recent years, malfunction of electronic equipment due to noise generated by electric (or electronic) equipment has become a more serious problem, and reduction of noise leakage has been more severely demanded. Therefore, in addition to the above method, a noise reduction filter is also formed outside the heater lead portion 11 of the magnetron 10. Figure 7 shows the choke coil 4
This is an example of configuring a T-type low-pass filter circuit by adding 0, and FIG. 8 is an example of configuring a common mode choke coil circuit using a ferrite ring 41 and two heater lead wires in common. These filters reduce noise leakage from the magnetron 10 to the power supply side.

[0007]

However, all of the filters having the above-mentioned configurations have magnetron heaters (cathodes).
Since it is located on the side, a high voltage of 3 to 4 kV is applied and a problem easily occurs in terms of safety.

The present invention has been made to solve the above problems, and an object thereof is to provide a microwave oven in which leakage of noise is reduced while considering safety.

[0009]

SUMMARY OF THE INVENTION The present invention, which has been made to solve the above problems, provides an element having a high impedance characteristic in a high frequency region in a path from an anode of a magnetron to a kitchen which is an electrically common ground. It is characterized in that it is inserted and an anode current is caused to flow through the element.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The element is made of a material having a large dielectric constant in a high frequency region, for example, ferrite, and a ferrite ring is formed around a gasket connected to an anode piece of a magnetron. Since the magnetron is attached to the microwave oven so that the microwave oven's microwave oven (strictly speaking, the waveguide) serves as the magnetron's ground, the anode current flows from the oven to the anode piece of the magnetron via this ferrite ring.

Further, since the magnetron is attached to the cooking cabinet by a screw or the like, a ferrite ring is formed around the screw mounting hole of the cooking cabinet, through which the anode current flows from the cooking cabinet to the casing of the magnetron and further to the anode. You may make it flow into one side.

[0012]

According to this, leakage of high frequency noise is reduced, and the filter element is in a place where high voltage is not applied, so that safety is maintained.

[0013]

1 is a perspective view of a magnetron which is an embodiment of a microwave oven according to the present invention, and FIG. 2 is a circuit diagram around the magnetron. In FIG. 1, a ferrite ring 50 is provided around the metal gasket 18 and is connected to the housing via the ferrite ring 50. The housing of the magnetron 10 is connected to a cooking space, which is a common ground, via mounting screws 19, as described later. That is, in terms of a circuit, the ferrite ring 50 functions as a feedthrough capacitor having high impedance in a high frequency band. Therefore, leakage of high frequency components of the radio wave oscillated by the magnetron 10 to the outside is attenuated.

FIG. 3 is a side sectional view of a microwave oven casing for explaining another embodiment. Magnetron 10
It is attached to the waveguide 62 at the upper rear of the cooking chamber 61.
When the magnetron 10 oscillates, the microwave energy emitted from the antenna 17 is diffused into the cooking chamber 61 through the waveguide 62. As shown in Fig. 3, magnetron 1
0 contacts the waveguide 62 only at the mounting screw 19. A ferrite ring 60 is arranged around the mounting screw hole on the waveguide 62 side so as to surround it. For this reason,
The anode current flowing from the waveguide 62 to the anode piece of the magnetron 10 always passes through the ferrite ring 60, and the circuit is the same as in FIG.

[Brief description of drawings]

FIG. 1 is a perspective view of a magnetron which is an embodiment of a microwave oven according to the present invention.

FIG. 2 is a circuit diagram around the magnetron of the embodiment of FIG.

FIG. 3 is a side sectional view of a microwave oven for explaining another embodiment of the microwave oven according to the present invention.

FIG. 4 is a circuit diagram around a conventional magnetron.

5A and 5B are a vertical partial cross-sectional view and a horizontal cross-sectional view, respectively, showing the structure of the magnetron shown in FIG.

FIG. 6 is a schematic diagram of a conventional magnetron oscillator circuit.

FIG. 7 is a circuit diagram around a conventional magnetron.

FIG. 8 is a circuit diagram around a conventional magnetron.

[Explanation of symbols]

 10 ... Magnetron 15 ... Anode piece 18 ... Metal gasket 19 ... Mounting screw 50 ... Ferrite ring 60 ... Ferrite ring

Claims (3)

[Claims] 1. An electron characterized in that an element having a high impedance characteristic in a high frequency region is inserted in a path from a magnetron anode to a cooking cabinet which is an electrically common ground, and an anode current is caused to flow through the element. range. 2. The microwave oven according to claim 1, wherein the element is a ferrite ring formed around a gasket connected to the anode piece of the magnetron. 3. The microwave oven according to claim 1, wherein the element is a ferrite ring formed around a member for attaching the magnetron to the cooking cabinet.