JPS58212094A - 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 The present invention relates to a high frequency heating device with an improved radio wave leakage prevention mechanism.

A microwave oven, which is a typical example of a conventional high-frequency heating device, uses a contact method using conductive grooves and grooves as a means to prevent radio wave leakage from the gap created between the heating chamber and the door.
Methods using radio wave absorbing materials, choke methods using resonance, etc. have been proposed and put into practical use.

One of the difficulties in constructing this radio wave leakage prevention mechanism is countermeasures against harmonics.

The l2+jL contact method also has the property 1 for this harmonic.
Although this is sufficient in principle, manufacturing precision is required to maintain contact precision. Also, the object to be heated q) (l
This contact method has a drawback in that the performance deteriorates significantly when the i-piece adheres.

Most radio wave absorbing materials exhibit only one or two times their performance within a predetermined band, and do not exhibit sufficient performance for both the fundamental wave and its harmonics.

However, in order to take advantage of the resonance, the choke system that uses resonance inevitably has an effect on the wavelength of the fundamental wave.
- Law is necessary. The conventional choke system configuration will be described below. Figure 1 shows a typical conventional choke-type radio wave leakage prevention mechanism. a is a block diagram, and Cb is a balance circuit.

The choke-type radio wave leakage prevention mechanism of 71″L is based on the radio wave passage 3 created by the flange 1 and the access door 2.
% of the fundamental wavelength of radio waves leaked from one person Z) Length B
A choke cavity 6 is arranged starting from 1', and this is a 4-component structure, and the Z-direction . First drawback. In addition, the impedance zB when looking from the choke cavity 6 side IJ':::aB to the choke cavity 6 side is ideally configured to be infinite for the fundamental wave. It is to the right for harmonics. Furthermore, if the impedance of this radio wave leakage prevention mechanism when looking at the space behind and behind the termination terminal C7 is ZL, then the equivalent circuit of this radio wave leakage prevention mechanism is as shown in figure b. One interference turn ZA of defense+l゛-n+8 is here λgi is the leakage radio wave wavelength, and e is the radio wave path length C5-E17.4°I11.6I:y J'-'Ip7. <u
41 (m, a, 1.

Since the oscillation wave number of the magnetron Q1, which is a typical example of a high-frequency heating device, fluctuates within 2460150 MH2 depending on the load, the radio wave length is limited to 7 monme due to the same restriction.

Therefore, for the fundamental wave, ZB −== j =:>−
v, Peng βe9keC'y:), it becomes ZA O, and the second harmonic becomes ZBo.

From 1entβC to O, ZA becomes ZL.

In the fundamental wave, the change in ZL, that is, the heating chamber 797
Although the variation in the gap at the C end caused by the assembly of the second part 1 and the door 2 can be absorbed by (-), for the second harmonic,
The second lack -1- has less margin.

(・In view of these circumstances, the invention introduces a parallel transmission line used for radio wave transmission into a radio wave leakage prevention mechanism, and connects a T-branch line to a part of the transmission line to create a new 7, 7, 9
To provide a radio wave leakage prevention mechanism with a mechanism that has ↑゛ which can be compared with the fundamental wave for harmonics θk of 4 mechanisms: S5-)El-J
The target is

The present invention will be explained below with reference to the drawings.

FIG. 2 shows the radio wave leakage prevention mechanism of the present invention, in which a is a purchase diagram and b is an equivalent circuit thereof.

The parts in the figure that are compared with Figure 1 are -k > 4.), -
4゛.

A group of 6 transmission lines 11 having a width W and arranged at a gap S with a transmission line M=i which are adjacent to and opposite to the heating chamber opening flange 1 are formed. This transmission line 6 (,1) A branch line 7 is placed at a certain length from end A of radio wave path 3.
, and its depth is approximately % of the leakage radio wave wavelength. The isometric circuit Q of such a transmission line is shown in figure b, as is well known in microwave engineering.

Here, the big difference from Figure 1 is that the width of the transmission line is W.
Because it is constrained by t<L, ? =
1. The presence of L-type rosettes. Considering this II band parameter and calculating the ZAO value by adjusting the depth of the branching path 7 to the A wavelength, the shorter el is, the ZA t, +
1'1 of the mechanism for preventing small wave leakage βb of the present invention as it approaches zero. Noh or 1f, I got the solidity to do 4, 1, 30 questions of EL to prove [this].

When measured as 12 o'clock, e is 12 ho or e+-30J
We were able to obtain a radio wave leakage tit result that is μ~Akira lower than that of II, and were able to theoretically and experimentally explain the radio wave leakage prevention mechanism of Shikou 4. This conclusion is well-known in the past.The fact that the radio wave 1 route in the Chofuka method, which was used as J-, reaches Chori-ku 111111, and the fact that the J' method is 'A wave IK,' is as shown in the present invention. By using a radio wave leakage prevention mechanism in which a transmission line consisting of T branches with a gap S of /1" is periodically arranged, the length el up to the branch point can be made sufficiently smaller than the % wavelength. Radio wave leakage in the Z direction, 1 (1 ≦) J heavy equipment tf#
-\#1 shows the feature that the j' method can be configured more compactly than the conventional choke method.

Since the depth of this ``wave leakage prevention + machine groove can be set to approximately % of the depth of the branching path, the depth of this branching path - J'' method is It is only necessary to effectively set the V4 wavelength to harmonics.

FIG. 3 is a block diagram of a means for preventing leakage of city waves 11 of a high-frequency heating apparatus according to a practical example of the present invention.

The branch paths 8a, 8b, Bo, 8d, and Be are filled with a dielectric material 9 having a predetermined dielectric constant, and the depth of the branch path filled with this dielectric material is adjusted to the fundamental wave of the leakage radio wave. In contrast, a branch path without a dielectric is constructed so as to have a false wavelength with respect to harmonics, and a branch path without a dielectric is constructed so as to have a false wavelength with respect to harmonics.

FIG. 4 is a sectional view of a radio wave leakage prevention means 11 showing another embodiment of the present invention.

These branch paths 10a and 10b have the same depth.

100. Shine mutually into the branch path for 10d and 10e/
(The eagle of the dielectric material of the same material is changed, and the depth of the branch path which is a false wavelength is formed for each base wave and harmonic wave based on the same constraint. In Figs. 2 to 4, 1.2 is the terminal short-circuit surface of the branch path.

In the configuration shown in Fig. 3, the T-branch path length is determined based on the dielectric constant of the dielectric material,7 while in the configuration shown in Fig. 4, the T-branch path length is determined based on the dielectric constant of the dielectric material. By configuring the filling rate of the dielectric material in the branch path appropriately, the fundamental wave and harmonics are made to have false wavelengths with equal constraints on -C, and the selection of the dielectric material is wide. It has the advantage of being

Note that it is not necessary to completely illuminate the dielectric material in the branch path for the fundamental wave, but in order to make the branch path more compact,
It is clear that the complete light beam will be the most compact.

Although FIG. 4 shows a case in which the dielectrics are individualized, a structure in which a one-piece dielectric whose thickness is periodically changed may be inserted into the branch path may be used.

Further, this radio wave leakage prevention means may be arranged on the access door or on the heating chamber side.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention provides a high-frequency heating device having a novel radio wave leakage prevention means in which transmission lines having a T-shaped cross section and having a branch line whose terminal end is short-circuited are arranged periodically. The filling rate of the dry city layer is 74. (1) Countermeasures against harmonics can be analytically designed.

(2) Measures against the fundamental wave and harmonics can be taken simply by changing the 1' ratio by filling the dielectric layer, making the design easy and the selection of the dielectric material easy.

(3) The radio wave leakage prevention means can be made more compact.

(4) The depth of the branch path is constant and manufacturing control is easy.

It has the following effects.

[Brief explanation of the drawing]

Fig. 1 shows the radio wave leakage μm month 1° + life structure of the conventional choke method, a is the configuration diagram, b is the equivalent circuit diagram, and Fig. 2 is the radio wave leakage prevention mechanism of the present invention, a is the configuration diagram. . b is an equivalent circuit diagram, and FIG. 3 shows one implementation of the present invention ψ11 at 71
Fig. 4 is a sectional view of a radio wave leakage prevention means showing another embodiment of the present invention. 1... Heating chamber flange, 2... Access door, 3... Radio wave passage, 6... Transmission line, 7.8 &, 8b. ac, sa, 86,101L, 10b, IC1゜10
d, 106... Branch road, 9, 11...
Dielectric 12... Short circuit surface. − Name of representative Patent attorney Toshio Nakao et al. 18th
1 Figure, 9 Figure 2 Figure 3 OL Figure 4

Claims (1)

[Claims] A heating chamber for accommodating an object to be heated, an access door for taking the object into and out of the heating chamber, and a radio wave leak prevention means provided in a radio wave passage formed by the heating chamber and the access door. The radio wave leakage prevention means has a periodic arrangement of transmission lines each having a T-shaped cross section and having a branch path whose terminal end is short-circuited, and the branch path includes dielectric layers having different filling factors. High frequency heating device.