JPS6258594A - 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.

Conventional technology All stages of magnetrons are installed approximately in the center of the top surface of the heating chamber, and a stirrer blade is placed directly below the output antenna of this magnetron. A proposal to provide such a system is found in Japanese Patent Publication No. 52-7583.

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 keep 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.
It has become difficult to meet the above needs.

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.

The only way to solve the problem is to install it opposite the output antenna of the magnetron, so that the long side of the magnetron is at the center of the antenna.

A rotating antenna having a substantially rectangular radiation opening whose short side is larger than the width of the used wavelength is provided.

Effect By configuring as described above, no spark is generated even if the output antenna tip is brought close to the rotating antenna, or even if the output antenna tip is passed through the radiation port of the rotating antenna, so that the single rotation antenna and the top surface of the heating chamber are connected to each other. The total amount of 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 houses all the objects to be heated, and 2 is a magnetron that generates high-frequency energy.
It is attached directly to the top surface 6 of the. 3 is the 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 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 completely cooling the magnetron 2 into the heating chamber i. 10 is a motor for rotating the ventilation fan 9. Reference numeral 11 indicates the air from the blower fan 9 to the heating chamber 1.
It is a wind control plate that can be easily entered inside. 12 is the rear of the outer box, 1
6 is the top surface of the outer box. 14 is a front flange of the heating chamber 1, 15 is an operation panel attached to this front flange, 16
is a door provided at the entrance of the heating chamber 10 so as to be openable and closable.

FIG. 1 is an enlarged view showing the mounting structure of the rotary antenna 4 in FIG. 6. 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 3. A cylindrical portion 19 is formed on the outer periphery of the cylindrical portion 19 and is integrated with the blade 5. The horizontal plate 24 is completely 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 facing 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 23 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 is composed of a metal flat plate having a substantially rectangular radiation hole 26 in the center. Long side 2 of radiation port 26
The dimension xd of 7 is larger than the percentage of the wavelength used by the magnetron 2, and the dimension y of the short side 28 is larger than the percentage of the wavelength used. That is, the radiation aperture 26 has a size approximately equal to the cross section of the waveguide through which the entire electromagnetic field of the TE1o mode is transmitted. An output antenna 6 is located approximately at the center of the radiation port 26, and a rotary antenna 4 rotates around the entire center of the output antenna 3. 29 is protrusion piece 2
A horizontal plate 24 integrated with one blade 5 through a small hole into which 0 is inserted.
This is for coupling the rotary antenna 4 to the rotary antenna 4.

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 3 of the magnetron 2 is radiated downward from the radiation port 26 at the center of the nine-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 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, since the one-rotation antenna 4 is rotated 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 changes from time to time, allowing for more uniform heating.

The sizes of the long side 27 and the 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 TEIO of waveguides normally used for high power applications, so the output antenna 5 is located at the radiation port. Even if the output antenna 3 and the rotary antenna 4 are brought completely close to each other by penetrating through the heating chamber 1, the heating chamber 1 is in an empty firing state with no material 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 9 According to the present invention, it is installed opposite to the output antenna of the magnetron, and the long side is thicker than % of the used wavelength (the short side is larger than % of the used wavelength). Since a rotating antenna with a substantially rectangular radiation opening is provided, sparks will not occur even if the output antenna passes through the radiation opening.Therefore, the positional relationship between the output antenna and the rotating antenna can be freely selected. The total idle space between the upper surface of the heating chamber and the upper surface of the heating chamber can be reduced, and the entire high-frequency heating device can be made compact.

[Brief explanation of drawings]

FIG. 1 shows the mounting structure of the rotating antenna 4 in the high-frequency heating device according to an embodiment of the present invention. In the enlarged view of the main parts shown,
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. 3...Output antenna, 4...Rotating antenna. 6...Top surface, 26...Radiation port.

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
6) A high-frequency heating device characterized in that a rotating antenna (4) having a rotary antenna (4) is provided.