JPS5916714B2 - High frequency heating device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high-frequency heating device that prevents frequency components other than the fundamental wave from being transmitted into a heating chamber by imparting frequency selectivity to a waveguide section.

A high-frequency heating device with a closed structure has a door portion for taking in and out the heated object, and in order to ensure safety, this door portion must be provided with a structure to prevent radio wave leakage.

In the conventional technology, the radio wave leakage prevention structure is designed for the fundamental wave with the highest power level, so the leakage prevention effect is not sufficient for frequencies other than the fundamental wave. Furthermore, if a leakage prevention structure that is effective over a wide band 5 is to be adopted, the structure must become complicated and large. In order to improve this point, there is a known technique in which conductor rods of different lengths are made to protrude inside the waveguide to prevent noise frequencies other than the fundamental wave from entering the heating chamber. The frequency to be blocked is determined by the length, and the frequency width is very narrow. Therefore, considering that the noise distribution usually changes over time, implementation is difficult. In addition, by increasing the number of conductor rods, it is possible to widen the frequency range that can be blocked, but this band is limited to a frequency band lower than the fundamental wave, and the blocking effect is limited to a frequency band higher than the fundamental wave. There isn't. The present invention has been developed in view of the drawbacks mentioned above, and has been improved by eliminating noise frequencies other than the fundamental wave within the waveguide and transmitting only the fundamental wave to the heating chamber. This simplifies the leakage prevention structure and more completely prevents radio wave leakage.

In order to transmit only the fundamental wave to the heating chamber and block the propagation of other noise frequencies, a plurality of conductor rods or a plurality of conductor plates having a width in the tube axis direction are installed inside the waveguide. They should be inserted parallel to or at an angle to the electric field in the waveguide, and both ends of these conductors should be in contact with the waveguide tube wall. By inserting one conductor having a width in the tube axis direction and having both ends contact the waveguide tube wall, the conductor has blocking characteristics against the fundamental wave, but if multiple conductors are inserted, As a result, they are electromagnetically coupled to form a resonant circuit, with the characteristic that only the fundamental wave is transmitted and other frequencies are blocked.

Embodiments of the present invention will be described with reference to the accompanying drawings.

In Fig. 1, 1 is a heating chamber, 2 is a heating chamber to 0-A, and 3 is a heating chamber.
4 is a waveguide, 4 is a coupling hole between the heating chamber and the waveguide, 5 is a magnetron antenna, 6 is a magnetron, and 7 is a conductor plate inserted into the waveguide.

FIG. 2 is an enlarged and partially cutaway perspective view of the waveguide section of FIG. 1, in which the conductor plate has a width in the axial direction of the waveguide.

In this case, in terms of the circuit, each conductor plate functions as an inductive element, and the interval between each conductor plate functions as a capacitive element, and the center interval of each conductor plate is approximately By choosing λ/2, only the fundamental wave can be passed. In addition, if the conductor plate is inserted into a high-frequency heater that has been impedance matched without changing the conductor plate, the impedance matching will be lost, but in this case, the slope of the conductor plate with respect to the electric field in the waveguide will be changed. The impedance matching can be re-established by changing the waveguide or by translating the conductor plate along the cross section of the waveguide.

Furthermore, although a conductor plate was used in the above embodiments, the same effect and characteristics can be obtained even if the negative part or the whole part is replaced with a conductor rod.

As explained above, the present invention configures a circuit that allows only the fundamental wave to pass through by arranging a plurality of conductor plates or conductor rods with their ends in contact with each other at appropriate intervals within a waveguide. It has become possible to more completely prevent electric wave leakage, and to simplify the structure of the door to prevent electric wave leakage.

Furthermore, since the configuration is simple, it can be implemented at low cost.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a high-frequency heater showing an embodiment of the present invention, and FIG. 2 is a perspective view showing a main part of the waveguide with a part thereof cut away. 3... Waveguide, 7... Conductor plate.

Claims (1)

[Claims] 1 In a high-frequency heating device that transmits radio waves from a high-frequency oscillator to a heating chamber through a waveguide, a plurality of conductor rods, a plurality of conductor plates, or a plurality of conductor plates and conductor rods are guided in the waveguide. A component of a resonant circuit in which each conductor is electromagnetically coupled by inserting it parallel to or at an angle to the electric field in the wave tube and bringing both ends of the conductor rod or plate into contact with the waveguide wall. A high-frequency heating device characterized in that most frequency components other than the fundamental wave of the high-frequency oscillator are reflected to the high-frequency oscillator side, and only the fundamental wave is sent into the heating chamber.