JPS61292893A - 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 the Invention The present invention relates to a high-frequency heating device, and more particularly to a radio wave leakage prevention structure for an openable and closable door provided at the entrance of a heating chamber of a high-frequency heating device.

A conventional high-frequency heating device heats or cooks food placed in a heating chamber using high-frequency energy supplied from a magnetron, which is a source of high-frequency radio waves. This high-frequency heating device is equipped with a door that can be opened and closed.

There is a slight gap between the main body of the heating chamber and the door.
Radio waves leak to the outside through this gap.

It is necessary to keep the amount of leakage below the legally permissible value, taking into account all negative effects on the human body, etc., and for this purpose, a leakage prevention mechanism is mainly provided on the door surface.

A typical mechanism for preventing radio wave leakage in doors is the choke method, in which a choke structure with a groove for attenuating radio waves is placed around the periphery of the door, extending from the entrance of the radio wave passage formed by the heating chamber and the door to the groove. There is a means to set the dimension of the groove and the length of the groove to be one wavelength of the radio wave used. According to this method, the entrance of the radio wave path is equivalent to being short-circuited in terms of impedance, and has the advantage of preventing radio wave leakage. However, on the other hand, since the length of the groove is specified, There was a problem in downsizing the overall structure of the heating device. Also as another radio wave leakage prevention mechanism.

For example, JP-A No. 58-216388 and JP-A No. 52-
As shown in Publication No. 40461, a means for preventing leakage of radio waves by arranging periodic structures in radio wave paths and f-z-shaped structures to regulate the direction of radio wave propagation has also been put into practical use. However, it was not possible to respond to the need for smaller doors.

The problem that the invention aims to solve It is difficult to make the door smaller.

A means for solving the problem, that is, the present invention provides the above-mentioned device by providing a groove (hereinafter referred to as groove) surrounded by metal having a substantially U-shaped cross section in one peripheral portion of the door body. At the same time, the opening of the groove is opened facing the opening peripheral wall (opening flange part or sash plate part) of the heating chamber, and an insulating plate having conductive stripes on the surface is placed at the bottom of the groove. and also houses the base portions of at least one pair of leaky radio wave transmission lines having bent pieces, and electrically connects the conductive wire and the base portions of the transmission lines to form a leaky radio wave transmission line. The opening side of the transmission line is aligned with the opening side of the groove, and the transmission line is supported so as not to contact the inner wall of the groove, and the transmission line is provided periodically in the longitudinal direction of the groove. In addition, radio wave leakage is reduced by selecting specific conditions such as the shape, position, length, and width of the transmission line.

Moreover, by configuring a thin door, the high frequency heating device can be made smaller.

The impedance of the transmission line is changed by changing the shape, length, width, etc. of the leakage radio wave transmission line, so that the impedance when looking inside from the opening of the groove is open, and the leakage radio waves are multi-reflected. decreases over and over again.

Example An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing the appearance of the high-frequency heating device of the present invention. In the figure, 1 is a heating chamber that stores the object to be heated, and 2 is a cabinet that surrounds the heating chamber 1f.

The front edge of the cabinet 2 extends the metal plate that makes up the cabinet 2 and surrounds the door 3.

A sash plate 4 is formed as a part of the opening peripheral wall of the heating chamber 1. Reference numeral 5 denotes a flange portion that surrounds the entire circumference of the opening of the heating chamber 1, and constitutes a part of the peripheral wall of the opening of the heating chamber. Reference numeral 6 denotes an operation section and display section for operating the high-frequency heating device, 7 a door handle, and 8 a viewing window.

FIG. 2 is a cross-sectional view showing an embodiment of the high-frequency heating device of the present invention, and FIG. 6 is an enlarged cross-sectional view of the main part of FIG. The same parts as in Figure 1 are indicated by the same numbers. As shown in the figure, a part of the side wall 9 of the heating chamber 1 is bent to form a flange part,
Its extension has an upright satshu plate 4,
This sash plate 4 and the flange portion constitute a heating chamber opening peripheral wall 5 that fully supports the door. In front of the flange portion, radio wave seal portions disposed on the peripheral edge of the door body B are placed facing each other, and the two are partially in contact with each other. The radio wave seal mechanism is composed of a groove formed of metal and a plurality of transmission lines housed within the groove. That is, there is a metal groove 10 having a substantially U-shaped cross section in the door body 3, forming a groove space 11. Also, the opening 1 of the groove 10
2 is open toward the flange portion 5. There are heat-resistant elastic bodies 13a and 13b in the groove space 11, and an insulator plate 14 made of a ceramic material or a heat-resistant plastic material is placed on one side of the elastic bodies. 15 (15a, 1
5b) is a conductive line formed on the surface of the insulator plate 14, and is formed into a transmission line having the necessary line width, thickness, and length by baking, photoresist, or the like. 16 (16a
, 16b) is an elongated metal member that constitutes the center of the base portion of the leaky radio wave transmission line, and one end thereof becomes a bent portion 17 (17a, 17b) and the conductive wire 1
5 (15a, 15b) to be electrically connected. The other ends are horizontal ends 18 (18a, 18a,
18b) to face the flange portion 5. In this way, the leakage radio wave transmission line constituted by the base portion and the conductive wire is arranged periodically in the longitudinal direction of the groove. In the figure, 19 is the opening 12 of the groove.
20 is a gap portion through which radio waves leak.

Figure 4 is a partially cutaway perspective view showing details of the radio wave seal mechanism;
FIG. 5 is an enlarged perspective view of a main part showing the shape of a conductive wire that is a component of a transmission line. In FIG. 4, the plastic cover covering the groove opening has been removed.

In FIG. 4, the groove 10 is surrounded by a flat bottom surface 21 and vertical walls 22a, 22b perpendicular to the bottom surface 21.
Its cross section is U-shaped, has a predetermined length, and forms the door periphery. The outer wall 23a of this groove 10.

23b has a side wall portion 24 that is engaged with the side wall portion 23b, and these side wall portions serve as supports for a transmission line, which will be described later.

In these side wall portions that are in close contact with the outer wall surface of the groove 10.

horizontal ends 18 (18a, 18b, 18c) partially extended and bent at right angles and parallel to the bottom surface 21;
, 18d), whose horizontal ends are also parallel to the flange surface of the heating chamber. Width W of this horizontal end
is 20~25■, and the pitch 'fP in the longitudinal direction of the groove is 3
5 to 50 ■. Each horizontal end is connected to an elongated metal member 16 (16a, 16b) that is perpendicular to the end surface, and the tip thereof is bent at right angles toward the inside of the groove to form a bent portion 17 (17a, 16b). 17b)'
t-forming. That is, the portion formed by 16, 17, and 18 is the base portion of the transmission line. Heat-resistant elastic bodies 13a and 13b are fixed on the bottom surface 21 of the groove,
Furthermore, a flat insulator plate 14 made of a heat-resistant resin material or a ceramic material is fixedly supported on this. 15
is a conductive wire formed on the insulator plate 14, and its line width, length, thickness, and shape are appropriately selected so that the amount of leakage is at a low level. As shown in FIGS. 26a and 26b, the ends of the conductive wire 15 have a larger surface area than the conductive wire 15, and are electrically connected to the bent portions 17a and 17b to prevent leakage of radio waves. transmission line is formed.

FIG. 6 is a perspective view showing another example of the structure of the conductive filament. In the figure, there is a second insulator plate 27 on top of the insulator plate 14, and conductive wires 15 are provided on both the front and back surfaces of the second insulator plate 27. For example, between the ends 26c and 26a, a coil of conductive wires is connected. The coil pitch, overall length, etc. are closely related to the amount of leakage. Here, the conditions are that the cross-sectional area of the line is 1 to 2-2 and the total length is 60 to 80 cm.

A conductive wire made of copper with a diameter of about 2 to 4 tan.

A transmission line is formed by two transmission line base parts with a width of 2.5 to 5 cm and a straight part length of about 15 mm, each having a horizontal end face and a bent part, and this transmission line assembly is aligned in the longitudinal direction of the groove. The amount of radio wave leakage when arranged in the same direction was less than the legally regulated value, confirming that it is a highly safe means of preventing radio wave leakage.

The amount of radio wave leakage is reduced by such a transmission line configuration because the impedance of the transmission line can be freely changed by forming a thin, long, or coiled line, and the impedance of the transmission line can be changed freely from the opening of the groove. This is thought to be due to the fact that when the internal impedance is made to be open, leakage radio waves are reduced through multiple reflections.

Effects of the Invention As described above, according to the present invention, as a door component in a high frequency heating device, a base portion of a transmission line made of a metal plate is electrically connected to the base portion of a transmission line in a groove having a rectangular cross section. A transmission line for leakage radio waves is formed by the conductive wires formed on the insulator plate, and by periodically arranging the transmission line in the longitudinal direction in the groove, the flange which is the opening peripheral wall of the heating chamber is formed. This has the advantage of suppressing radio waves leaking from the gap between the door and the door to an extremely low level, providing a safe high-frequency heating device. Furthermore, in the radio wave sealing means, the leakage prevention effect can be achieved even if the depth of the groove and the height of the base portion of the transmission line housed in the groove are smaller than 1 of the radio wave wavelength for convenience, so it is possible to reduce the size of the door and This has the advantage that the device can be made more compact.

As another embodiment of the present invention, it is also possible to partially form conductive wires on a plurality of insulator plates and combine them to form a flat coil. The same effect as the present invention can be obtained even if the opening of the U-shaped groove and the transmission line are rotated by 90 degrees to face the sash plate, and the side wall surface of the U-shaped groove is in contact with the flange.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the external appearance of a high-frequency heating device according to an embodiment of the present invention, FIG. 2 is a sectional view of the high-frequency heating device according to an embodiment of the present invention, and FIG. 3 is an enlarged view of the main part of FIG. 2. 4 is a sectional view, and FIG. 5 is a partially cutaway perspective view showing the radio wave sealing mechanism in the present invention. FIG. 6 is an enlarged perspective view of a main part showing the shape of a conductive wire that is a part of a transmission line. 1...Heating chamber, 3...Door. 5... Opening peripheral wall, 10... Groove. 14... Insulator plate, 16... Metal member. 17...Bending portion, 18...Horizontal end portion. 15... Conductive filament.

Claims (1)

[Claims] In a heating chamber that stores an object to be heated and a door that can be opened and closed at the opening of the heating chamber, a metal groove (10) having a substantially U-shaped cross section is provided at the periphery of the door (3). The opening is opened facing the opening peripheral wall (5) of the heating chamber (1), and a metal member (16) and a bent portion (
A base portion of a leaky radio wave transmission line consisting of a horizontal end portion (17) and a horizontal end portion (18), and an insulator plate (14) having a conductive line (15) on its surface are housed, and a bent portion (18) of the base portion is housed. 17
) and the conductive wire (15) are electrically connected to form a leakage radio wave transmission line, and the horizontal end side of this radio wave transmission line is the opening of the groove (10),
A high-frequency heating device characterized in that grooves (10) are provided periodically in the longitudinal direction.