JPS6258598A - 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. Description of the Related Art Japanese Patent Publication No. 7586/1986 proposes that a magnetron is provided approximately at the center of the upper surface of the heating chamber, and a stirrer blade is provided 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.

However, recently, there has been a growing need for lighter, thinner, shorter, and smaller devices, 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, which makes it impossible to meet the above needs. Ta.

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 Problems A magnetron is provided opposite to the output antenna of the magnetron, and its long side approximately centered on the output antenna is thicker than 1/2 of the wavelength used.

A rotating antenna having a substantially rectangular radiation opening whose short side is larger than 1/4 of the wavelength used is provided, and a notch having a width larger than 1/2 of the wavelength used is provided at the periphery of the antenna.

Effect By configuring as described above, no spark is generated even if the tip of the output antenna is brought close to the full-rotation antenna, or even if the tip of the output antenna is passed through the radiation port of the full-rotation antenna. Idle space can be completely 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 Figure 6, 1 is a heating chamber that houses all the objects 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 3 and re-radiates it, and is located approximately in 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 with high frequency transparency.

Reference numeral 8 denotes an air blowing port consisting of a large number of small holes, which is provided to allow air from a blowing fan 9 for completely cooling the magnetron 2 to enter the heating chamber 1. 10 is a motor for rotating the ventilation fan 9. Reference numeral 11 denotes a baffle plate that makes it easier for the wind from the blower fan 9 to enter the heating chamber 1. 12 is the rear of the outer box,
10 is the top surface of the outer box. 14 is the front flange of heating chamber 1, 15 is a companion operation panel attached to this front 7 flange, 1
Reference numeral 6 denotes 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 frequency waves, and a part of the rotating shaft 18 extends to form a cylindrical portion 19 that surrounds the tip of the output antenna 6. A cylindrical portion 19 is formed on the outer periphery of the cylindrical portion 19 and is integrally formed with the blade 5. 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 through a connecting surface 21 that faces the tip of the output antenna 6.

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 2 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 press-fitted into the cylindrical portion 19, and the rising portion 23 is such that the horizontal plate 24 and the cylindrical portion 19 form a right angle to each other, and the horizontal plate 24 The purpose is to minimize the total slope of . 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 6 and the output antenna 6. In FIG. 2, only those made of metal are shown. The rotating antenna '4 has a substantially rectangular radiation opening 26 in the center.
It is made up of a flat metal plate with a holder. The dimension X of the long side 27 of the radiation aperture 26 is larger than 1772, which is the working wavelength of the magnetron 2, and the dimension y of the short side 28 is thicker than 1/4 of the working wavelength. That is, the radiation aperture 26 has a size comparable to the cross section of a waveguide that transmits the TE10 mode electromagnetic field. An output antenna 6 is located approximately in the center of the radiation port 2B, and a rotary antenna 4 rotates around this output antenna 3.

Reference numeral 29 denotes a small hole into which the protruding piece 20 is inserted, which is integrated with the two blades 5 to connect the horizontal plate 24 and the rotating antenna 4. 30 is a notch provided to adjust the position of high frequency energy radiation from the periphery of the rotating antenna 4;
The width 2 of this cut 3o is larger than 1/2 of the wavelength used.

Next, all the effects of the embodiment configured as described above will be explained. A part of the high-frequency energy radiated from the output antenna 3 of the magnetron 2 is radiated downward from the antenna cover 7 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 frequency energy radiated from the output antenna 3 is radiated from the center and periphery of the rotating antenna 4, so the positional relationship between the tip of the output antenna filter and the radiation port 26, the size of the notch 30 of the rotating antenna 4 and the radiation port 26, etc. By relatively adjusting the temperature, the object to be heated placed in the heating chamber 1 can be heated from the periphery and center of the object and can be heated uniformly. Furthermore, since the rotating antenna 4 is configured to rotate Q by applying the wind from the cooling fan 9 to the blades 5, the direction of the electric field radiated from the radiation port 26 and the notch 30 changes from time to time, making it even more Allows for uniform heating.

The sizes of the long side 27 and short side 28 of the radiation port 6 are selected to be similar to the cross-sectional dimensions that allow transmission of the fundamental mode TE10 of a waveguide normally used for high power applications, so the output antenna 3 is located at the radiation port. Even if the output antenna 3 and the rotary antenna 4 are brought close to each other by penetrating through the heating chamber 1, the heating chamber 1 is completely burnt out with no object to be heated inside.

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

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

In addition, since the rotary antenna has a radiation port with a cross-sectional size similar to that capable of transmitting the fundamental mode port 10 of a waveguide used for high power, even if the output antenna completely passes through the radiation port, No spark occurs. therefore,
The positional relationship between the output antenna and the rotating angle can be freely selected, and the idle space between the rotating antenna and the top surface of the heating chamber can be reduced.

The entire high-frequency heating device can be made compact.

Furthermore, by adjusting the dimensions of the radiation opening and the notch, uniform heating, which is the original purpose of the rotating antenna, can be improved.

[Brief explanation of drawings]

FIG. 1 is an enlarged view of the main parts showing the structure of the installation of a rotary antenna in a high-frequency heating device according to an embodiment of the present invention, and FIG. 2 is an output antenna 6 and a rotary antenna viewed from the direction of arrow AB in FIG. 4, and FIG. 6 is a schematic cross-sectional view of the main part of the high-frequency heating device of the present invention. 1... Heating chamber, 2... Magne I Ron. ro...output antenna, 4...rotating antenna. 6...Top surface, 26...Radiation port. 27...long side, 28...short side. Ro0...cut, Z...width.

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 rotating antenna (4) having a width (6) is provided, and a width (
A high-frequency heating device characterized in that it is provided with a notch (30) having a shape of z).