JPS6243318B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a high frequency heating device.

The biggest problem with current devices of this type is eliminating uneven heating.

Conventionally, methods for solving this problem include providing a stirrer or a turntable. The former attempts to eliminate uneven heating by making the electric field strength in the heating chamber uniform by stirring the microwave in the heating chamber, and the latter aims to eliminate uneven heating by passing the object to be heated through electric fields of different strengths. This is intended to eliminate uneven heating by producing an effect similar to when all objects to be heated are placed under a uniform electric field.

However, installing a stirrer or a turntable inside the heating chamber is complicated and costly, and the effective volume of the heating chamber (the space in which the object to be heated can be placed) is
decreases, which is not desirable.

FIG. 1 shows a high-frequency heating means that has already been proposed to solve the above problem, where 1 is a heating chamber, 2
is a waveguide that communicates with the heating chamber through power feed ports 3a and 3b, and the power feed ports 3a and 3b are arranged in a line in the direction of microwave propagation as indicated by arrow A in the figure. 4 is a magnetron serving as a microwave supply means for supplying microwaves to the heating chamber 1 through the waveguide 2; 5 is a shorting plate disposed within the waveguide 2 perpendicular to the direction of propagation of the microwaves; The shorting plate is made of metal. Reference numeral 6 denotes a sliding means for sliding the shorting plate 5 in parallel to the direction of propagation of the microwave.

In such a device, when microwaves are oscillated from the magnetron 4 and the shorting plate 5 is continuously slid in the direction of arrow B in the figure by the sliding means 6, the shorting plate 5 is made of metal, so that the inside of the waveguide 2 is removed. The excitation phase of changes. When such a phase change occurs, the mode of the microwaves supplied into the heating chamber 1 from the power supply ports 3a and 3b also changes continuously, and therefore
The electric field strength within is also approximately uniform, and uneven heating does not occur.

However, in such a device, since the shorting plate 5 is made of metal, sparks occur between the shorting plate 5 and the waveguide 2, making it difficult to use in practice.

The present invention has been made in view of the above-mentioned problems, and will be described below with reference to Examples.

FIGS. 2A to 2C show one embodiment of the present invention, and the first
The difference from the figure is that the shorting plate 5 and the sliding means 6 are removed, and instead a dielectric resonator 11 is arranged between the feed ports 3a and 3b, and the dielectric resonator 11 is placed between the feed ports 3a and 3b. This is because a rotating means 12 is provided for rotating parallel to the surface in which the holes are formed. In addition, the same numbers are attached to the same parts in FIGS. 2A to 2C as in FIG. 1.

The coupling strength of the dielectric resonator 11 with the microwave changes depending on the coupling direction with the microwave. When the resonator 20 is most strongly coupled to the microwave A traveling in the direction perpendicular to the axc plane,
Coupling with microwaves traveling in other directions results in a weaker coupling force than the above, or no coupling at all.

Here, in the dielectric resonator 11 of this embodiment,
Two parallel surfaces 11a and 11b of such a resonator
Maximum coupling is assumed to occur with microwaves traveling perpendicular to

In the device of this embodiment configured in this way,
When the magnetron 4 oscillates microwaves and the rotating means 12 rotates the dielectric resonator 11, the surfaces 11a and 11b are positioned perpendicular to the direction of propagation of the microwaves (arrow direction in the figure). Then (resonance mode) (FIG. 2B), the microwave is coupled with the dielectric resonator 11, and the microwave is transmitted to the feed port 3a side located opposite to the magnetron 4, with the dielectric resonator 11 as the center. Almost never reached. Further, when the surfaces 11a and 11b are parallel to the direction of propagation of the microwave (non-resonant mode), the microwave does not couple with the dielectric resonator 11, so the microwave is transmitted from both the feed ports 3a and 3b to the heating chamber 1. It will be supplied to

In the above explanation, we have explained two extreme cases: a case where the microwave resonates most strongly with the dielectric resonator 11 and a case where it does not resonate at all. However, in reality, the dielectric resonator rotates in an analog manner. The bond strength also changes analogously. Therefore, the amount of microwaves supplied to the heating chamber 1 from both coupling ports 3a and 3b also changes.

This rotation of the dielectric resonator 11 is substantially the first rotation.
This has the same effect as the sliding of the shorting plate 5 in the device shown in the figure. In other words, due to a change in the coupling force of the dielectric resonator 11, the excitation phase of the microwave within the waveguide 2 changes. Therefore, since the mode of the microwaves supplied into the heating chamber 1 from each power supply port 3a, 3b changes continuously, the electric field strength within the heating chamber 1 is also uniform, and uneven heating does not occur. Further, since the dielectric resonator 11 is not made of a conductive material, sparks are not generated between the dielectric resonator 11 and the waveguide 2.

A suitable example of the dielectric resonator 11 is made of barium titanate with a relative dielectric constant εγ=90, and has a height a
A dielectric resonator having a length b of 15 mm, a length b of 1.5 mm, and a width c of 6 mm may be arranged such that the b×c plane is parallel to the plane of rotation of the dielectric resonator 11.

As is clear from the above description, the high-frequency heating device of the present invention can make the electric field distribution in the heating chamber uniform without using a stirrer or a turntable, so the effective volume is widened and the usability is improved. Furthermore, unlike the device shown in FIG. 1, there is no spark generated within the waveguide, so safety is high.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a conventionally proposed high-frequency heating device, FIGS. 2 A to C show embodiments of the present invention, FIG. 2 A is a sectional view, and FIGS. 2 B and C are top views. , FIG. 3 is a perspective view for explaining a dielectric resonator. 1... Heating chamber, 2... Waveguide, 3a, 3b...
Power feeding port, 11... dielectric resonator, 12... (rotation) means.

Claims (1)

[Claims] 1. A heating chamber, a waveguide disposed outside the heating chamber and having a plurality of power feeding ports for communication with the heating chamber, a microwave supply means for supplying microwaves to the heating chamber via the waveguide, and the above. A dielectric resonator disposed between the feed ports in a waveguide, and means for alternately changing the dielectric resonator into a resonant mode and a non-resonant mode with respect to the microwave passing through the waveguide. A high-frequency heating device characterized by: