JPS6258596A - High frequency heater - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an improvement in heating unevenness reducing means for a high frequency heating device.

2. Prior Art Japanese Patent Publication No. 7583/1983 proposes to provide a magnetron approximately at the center of the upper surface of the heating chamber, and to provide a stirrer blade directly below the output antenna of the magnetron. In this conventional example, unless a sufficient distance is maintained between the stirrer blade and the tip of the output antenna, sparks may occur near the tip of the output antenna and damage the magnetron. but,
Recently, there has been a growing need for lighter, thinner, shorter and smaller products, and it has become necessary to provide high-frequency heating devices that reduce idle space and have compact external dimensions. In the conventional example, in order to prevent sparks, it is necessary to maintain a sufficient distance between the stirrer blade and the tip of the output antenna, and to widen the idle space between the stirrer blade and the top surface of the heating chamber, making it impossible to meet the above needs. It's here.

Problem to be Solved by the Invention When attempting to reduce the idle space between the top surface of the heating chamber and the stirrer blade, sparks occur between the stirrer blade and the tip of the output antenna of the magnetron.

There is a risk of damage to the magnetron.

Means for solving the problem: A magnetron is installed opposite to the output antenna of the magnetron, and its long side is approximately half the wavelength of the wavelength used.

A rotating antenna made of a metal disk having a substantially rectangular radiation opening whose short side is larger than 1/4 of the wavelength used is provided.

Effect By configuring as described above, no spark is generated even if the tip of the output antenna is brought close to the rotating antenna or even if the tip of the output antenna is passed through the radiation port of the rotating antenna. Idle space can be reduced.

Embodiment The structure and operation of a high-frequency heating device according to an embodiment of the present invention will be explained with reference to the drawings.

In Fig. 3, 1 is a heating chamber that stores the object to be heated, 2 is a magnetron that generates high frequency energy, and heating chamber 1
It is attached directly to the top surface of the 6 is an output antenna of the magnetron 2.

Reference numeral 4 denotes a rotating antenna that combines with the electromagnetic field radiated from the output antenna 6 and re-radiates it, and is located approximately at the upper center of the heating chamber 1. A vane 5 is made of a dielectric material that transmits high frequencies. An antenna cover 7 supports and covers the rotating antenna 4, and is made of a dielectric material that is transparent to high frequencies. 8
is an air outlet consisting of a large number of small holes, and is provided to introduce air from an air blower fan 9 for cooling the magnetron 2 into the heating chamber 1. 10 is a motor for rotating the blower fan 9. 1) The air from the blower fan 9 is sent to the heating chamber 1.
It is a wind control plate that makes it easier to get inside. 12 is the rear of the outer box, 1
3 is the top surface of the outer box. 14 is the front 7 flange of the heating chamber 1, 15 is the operation panel attached to this front flange, 16
is a door provided at the entrance of the heating chamber 1 so as to be openable and closable.

FIG. 1 is an enlarged view showing the mounting structure of the rotary antenna 4 in FIG. 3. A fixed shaft 17 provided on the antenna cover 7 rotatably supports a rotating shaft 18 of the rotary antenna 4.

The rotating shaft 18 is formed of a dielectric material that transmits high frequencies, and a part of the rotating shaft 18 extends to form a cylindrical portion 19 that surrounds the tip of the output antenna 6, and a blade 5 is integrally formed on the outer periphery of the cylindrical portion 19. The horizontal plate 24 is fixed. The rotating antenna 4 is attached to the horizontal plate 24 by protrusions 20 provided at several locations. The rotating shaft 18 and the cylindrical portion 19 are integrally formed via a connecting surface 21 that faces the tip of the output antenna 3.

At the joint portion between the cylindrical portion 19 and the horizontal plate 24, a protruding portion 22 is provided on the cylindrical portion 19 side, and a rising portion 26 is provided on the horizontal plate 24 side. The protruding portion 22 is used to position the horizontal plate 24 when the horizontal plate 24 is coupled to the cylindrical portion 19 by press fitting, and the rising portion 23 is such that the horizontal plate 24 and the cylindrical portion 19 are at right angles to each other, and the horizontal plate 24 is This is to minimize the slope of the curve. Reference numeral 25 denotes a low-friction washer made of fluororesin or the like, which is inserted to reduce the friction between the tip of the rotating shaft 18 and the antenna cover 7.

Figure 2 shows the rotating antenna 4 seen from the direction of arrow AB in Figure 1.
This shows the positional relationship between the output antenna 3 and the output antenna 3. In FIG. 2, only those made of metal are shown. The rotating antenna 4 is composed of a metal disk having a substantially rectangular radiation opening 26 in the center. Long side 2 of radiation port 26
The dimension 2 of the magnetron 2 is larger than 1/2 of the wavelength used by the magnetron 2, and the dimension ν of the short side 28 is larger than 1/4 of the wavelength used. That is, the radiation aperture 26 has a size approximately equal to the cross section of a waveguide that transmits the TE mode electromagnetic field. An output antenna 3 is located approximately at the center of the radiation port 26, and a rotary antenna 4 rotates around the output antenna 3. Numeral 29 is a small hole into which a protruding piece 20 is inserted, and is used to connect the horizontal plate 24, which is integrated with one blade 5, and the rotating antenna 4. Note that the outer diameter of the nine-turn antenna 4 is selected so as not to match an even number multiple of 1/2 of the wavelength used.

Next, the effects of the embodiment configured as described above will be explained. A part of the high frequency energy radiated from the output antenna 6 of the magnetron 2 is radiated downward from the radiation port 26 at the center of the one-rotation antenna 4, and the rest is radiated from the rotary antenna 4 and the upper surface 6 of the heating chamber 1. After passing between the two, it is radiated from around the rotating antenna 4 to below the antenna cover 7. In other words, the high frequency energy radiated from the output antenna 3 is radiated from the center and the periphery of the rotary antenna 4, so the positional relationship between the tip of the output antenna B and the radiation port 26 (9) The external dimensions of the rotary antenna 4 and the dimensions of the radiation port 26. By making relative adjustments, the object to be heated placed in the heating chamber 1 can be heated from the periphery and the center, and uniform heating can be achieved. Furthermore, the one-rotation antenna 4 is a cooling fan? Since it is designed to rotate by applying wind from the blade to the blade 5,
The direction of the electric field radiated from the radiation port 26 changes from time to time, allowing for more uniform heating.

The sizes of the long side 27 and short side 28 of the radiation port 6 are selected to be the same as the cross-sectional dimensions that can transmit the fundamental mode TE of a waveguide normally used for high power, so the output antenna 6 Even if the output antenna 6 and the rotary antenna 4 are brought close to each other so that the antenna passes through the radiation port 6, the heating chamber 1 is completely burnt out without any object to be heated inside.

It has been experimentally confirmed that no spark occurs between the output antenna 6 and the rotating antenna 4.

Furthermore, since the outer diameter of the 9-turn antenna 4 is selected so as not to match an even multiple of 1/2 of the wavelength used, the electric field will not be at its maximum at the peripheral edge of the 9-turn antenna 4.

Abnormal heating of the blades 5 and the horizontal plate 24 made of dielectric material can be avoided.

Effects of the Invention As described above, according to the present invention, the antenna is disposed opposite to the output antenna of the magnetron and centered approximately thereon.

and the fundamental mode TE of waveguides used for high power.
Since the rotary antenna is made of a metal disk and has a radiation aperture with the same cross-sectional dimensions as those capable of transmitting, no spark will be generated even if the output antenna passes through the radiation aperture. Therefore, the positional relationship between the output antenna and the rotating antenna can be freely selected.

The idle space between the rotating antenna and the upper surface of the heating chamber can be reduced, and the entire high-frequency heating device can be made compact.

Further, by selecting the outer diameter of the nine-turn antenna so that it does not match an even multiple of 1/2 of the wavelength used, abnormal heating of the dielectric blades and horizontal plate can be avoided.

[Brief explanation of the drawing]

FIG. 1 is an enlarged view of the main part showing how the rotary antenna 4 is mounted in a high-frequency heating device according to an embodiment of the present invention.
Figure 2 shows the output antenna 3 seen from the direction of the AB arrow in Figure 1.
FIG. 6 is a schematic cross-sectional view of a main part of the high-frequency heating device of the present invention. 1. Heating chamber, 2. Magnetron. 6... Output antenna, 4... Rotating antenna. 6...Top surface, 26...Radiation port. 27... Long side, 28... Short side.

Claims (1)

[Claims] A magnetron (2) is directly attached to the top surface (6) of the heating chamber (1) that stores the object to be heated, and this magnetron (2)
The long side (27) is larger than 1/2 of the wavelength to be used, and the short side (27) is installed opposite to the output antenna (3) of
8) is a substantially rectangular radiation aperture (2
A high-frequency heating device characterized in that the outer diameter of the rotary antenna (4) does not match an even multiple of 1/2 of the wavelength used.