JPH0845659A - Waveguide tube switcher for high frequency heating device - Google Patents

Abstract

PURPOSE:To provide a wavegtuide tube switcher for high frequency heating device, with which it is practicable to suppress the microwaves propagating in the circumferential direction of a conductor plate for reducing the intensity of electric field and to suppress generation of electric discharge so that the safety and the reliability are enhanced. CONSTITUTION:Slits 90a in radial arrangement are formed in a pair of conductor discs 90 constituting a waveguide tube switcher for a high frequency heating device. Thereby the advancing direction of the microwaves intruding to the gap between the discs 90 and the wall of waveguide tube is restricted only to the radial direction, and it is practicable to set off the resonance conditions, reduce the intensity of electric field in the gap, and suppress the electric discharge.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waveguide switching device for a high frequency heating device used in a microwave heating device such as a microwave oven.

[0002]

2. Description of the Related Art A waveguide switching device for a high-frequency heating device of this type is used to switch a plurality of excitation ports in a microwave oven so as to perform optimum heating for a load. 7 (a) and 7 (b) are a plan view and a sectional view showing the configuration of such a waveguide switching device for a high-frequency heating device,
FIG. 8 is an exploded perspective view showing the structure of the main part of the waveguide switching device for the high frequency heating device shown in FIG.

In FIGS. 7 and 8, a rectangular waveguide 1 extending upward is connected to a magnetron (not shown), and microwaves from the magnetron propagate. The lower end of the waveguide 1 is connected to the waveguide switching device 3,
The waveguide switching device 3 is connected in a T-shape to the other waveguides 5 and 7 that are branched to the left and right. The microwave propagating through the waveguide 1 is switched by the waveguide switching device 3 and propagated to either the waveguide 5 or 7.

As is clear from the cross-sectional view shown in FIG. 7B, the waveguide switching device 3 is a pair of waveguides provided in parallel to the H-plane, which is the plane where the long sides of the cross-section of the waveguide 1 contact. It has circular conductor plates 9 facing each other. The pair of circular conductor plates 9 has a pair of rotating shafts 11 extending vertically from the center of the outer surface thereof.
It can rotate around this rotating shaft 11.

Further, as can be seen from FIG. 7B, a substantially cylindrical conductor 13 is disposed between the pair of opposing circular conductor plates 9, and the conductor 13 is a circular conductor plate 9.
Can rotate in any direction with the rotation of, and when provided to the waveguide 5 as shown, the waveguide 5 can be shielded from microwaves. As a result, the microwave from the waveguide 1 is propagated only to the waveguide 7 via the waveguide switch 3.

Further, a choke structure 15 is provided in the gap portion of the H surface of the waveguide, which opposes the pair of circular conductor plates 9 on the upper and lower sides thereof. An opening 15a is formed on the H surface that is a part of the choke structure 15, and the opening 15a is the maximum point of the reflected microwave. The distance between the opening 15a and the dead end of the choke structure is ¼λg, and the distance between the opening 15a and the circumferential edge of the circular conductor plate 9 is ¼λg. The position of the circular periphery of the circular conductor plate 9 is the minimum point of the microwave level.

In the waveguide switching device for a high frequency heating apparatus constructed as described above, the circular conductor plate 9 and the H surface of the waveguide are electrically connected, and both end surfaces of the conductor 13 are the H of the waveguide. Since it is connected to the surface, the waveguide 5 is cut off by this, and the microwave from the waveguide 1 is switched and propagated toward the waveguide 7.

The choke structure 15 provided in the waveguide switching device for the high-frequency heating device configured and operating as described above is
While holding the circular conductor plate 9 rotatably, the rotating shaft 1
The microwave leakage from the gap 1 is suppressed, and the peripheral portion of the circular conductor plate 9 and the wall of the waveguide are electrically short-circuited so that the peripheral portion of the circular conductor plate 9 and the wall of the waveguide are electrically connected. It is intended to be continuous.

[0009]

When the size of the waveguide is changed due to demands for miniaturization and the like while maintaining the structure of the waveguide switching device for the high-frequency heating device configured as described above, a circular shape is used. Among microwaves that enter the gap between the conductor plate and the wall of the waveguide, there is a problem in that the electric field strength due to the microwave component propagating in the circumferential direction increases and the possibility of generating discharge increases.

The present invention has been made in view of the above,
The purpose is to suppress the microwave propagating in the circumferential direction of the conductor plate to reduce the electric field strength, suppress the occurrence of discharge, and improve the safety and reliability of the waveguide switching device for high-frequency heating devices. To provide a container.

[0011]

In order to achieve the above object, a waveguide switching device for a high-frequency heating apparatus according to the present invention is a waveguide that shares an H-plane, which is a plane where the long sides of a rectangular waveguide cross section contact. By providing a pair of rotatably opposed conductor plates parallel to the H-plane and sharing a rotation axis at the pipe branch point, and by setting a conductor vertically provided between the pair of conductor plates in front of the waveguide, In a waveguide switching device for a high-frequency heating device, in which a waveguide is cut off and a choke structure is formed in a gap on the H surface of the waveguide facing the conductor plate, radial slits are formed in the conductor plate. Is the gist.

Further, the waveguide switching device for the high-frequency heating apparatus of the present invention has a rotation axis parallel to the H-plane at the waveguide branch point sharing the H-plane, which is the plane where the long sides of the rectangular waveguide cross section contact. A pair of rotatably opposed conductor plates that share the same are provided, and the waveguide is cut off by setting a conductor vertically provided between the pair of conductor plates in front of the waveguide, and In a waveguide switching device for a high-frequency heating device in which a choke structure is formed in a gap between H faces of the waveguides facing each other, a radial slit is formed in a wall portion of the waveguide facing the conductor plate. Use as a summary.

Furthermore, the waveguide switching device for a high-frequency heating device of the present invention is parallel to the H-plane at the waveguide branch point sharing the H-plane, which is the plane where the long sides of the rectangular waveguide cross section contact, and the rotation axis is A pair of rotatably opposed conductor plates that share the same are provided, and the waveguide is cut off by setting a conductor vertically provided between the pair of conductor plates in front of the waveguide, and In a waveguide switching device for a high-frequency heating device, wherein a choke structure is formed in a gap between H faces of the waveguides facing each other, a gap between the conductor plate and a wall portion of the waveguide facing the conductor plate. The gist of the present invention is to have a projecting portion that is periodically formed in the circumferential direction of the conductor plate so as to periodically change the height of the portion in the rotation direction of the conductor plate.

The waveguide switching device for a high-frequency heating device according to the present invention is characterized in that the projecting portion is formed by press squeezing.

Further, the waveguide switching device for the high-frequency heating device of the present invention has a rotation axis parallel to the H-plane at the waveguide branch point sharing the H-plane, which is the plane where the long sides of the rectangular waveguide cross section contact. A pair of rotatably opposed conductor plates that share the same are provided, and the waveguide is cut off by setting a conductor vertically provided between the pair of conductor plates in front of the waveguide, and In a waveguide switching device for a high-frequency heating device, wherein a choke structure is formed in a gap between H faces of the waveguides facing each other, a gap between the conductor plate and a wall portion of the waveguide facing the conductor plate. A dielectric plate having openings formed periodically in the same direction as the circumferential direction of the conductor plate so as to periodically change the height of the portion in the rotation direction of the conductor plate is formed on the conductor plate and the conductor plate. The gist is that it is provided between the wall portion of the waveguide and the wall portion of the waveguide which face each other.

[0016]

In the waveguide switching device for the high frequency heating device of the present invention,
Radial slits are formed in the conductor plate, and the traveling direction of the microwaves that enter the gap between the conductor plate and the wall of the waveguide is limited only to the radial direction.

Further, in the waveguide switching device for a high frequency heating apparatus of the present invention, a radial slit is formed in the wall portion of the waveguide facing the conductor plate, and the gap between the conductor plate and the wall of the waveguide is formed. The traveling direction of microwaves that enter the part is limited only to the radial direction.

Further, in the waveguide switching device for the high-frequency heating apparatus of the present invention, the height of the gap between the conductor plate and the wall portion of the waveguide facing the conductor plate is set in the rotating direction of the conductor plate. It has protrusions that are periodically formed in the circumferential direction of the conductor plate so as to change periodically, and the traveling direction of microwaves that enter the gap between the conductor plate and the wall of the waveguide is only in the radial direction. Is limited to.

In the waveguide switching device for the high-frequency heating device of the present invention, the protrusion is formed by press-squeezing.

Further, in the waveguide switching device for a high frequency heating apparatus of the present invention, the height of the gap between the conductor plate and the wall portion of the waveguide opposed to the conductor plate is set in the rotational direction of the conductor plate. A dielectric plate having openings formed periodically in the same direction as the circumferential direction of the conductor plate so as to be changed cyclically is provided between the conductor plate and the wall portion of the waveguide facing the conductor plate, The traveling direction of microwaves that enter the gap between the conductor plate and the wall of the waveguide is limited only to the radial direction.

[0021]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view of a circular conductor plate 90 used in a waveguide switching device for a high frequency heating apparatus according to an embodiment of the present invention. The waveguide switching device for a high frequency heating device to which the circular conductor plate 90 is applied has the same structure as that shown in FIGS. 7 and 8, and the waveguide switching device for a high frequency heating device shown in FIGS. The only difference is that the circular conductor plate 90 is used instead of the circular conductor plate 9 in the switch.

The circular conductor plate 90 of this embodiment shown in FIG.
A plurality of slits 90a are formed radially at predetermined intervals in the circumferential direction. A circular conductor plate 90 in which a plurality of slits 90a are radially formed is shown in FIGS.
When used in place of the circular conductor plate 9 in the waveguide switching device for the high frequency heating device shown in FIG. 1, the traveling direction of the microwave entering the gap between the circular conductor plate 90 and the waveguide wall by the plurality of slits 90a. Are restricted only in the radial direction of the circular conductor plate 90 and flow only in the direction parallel to the slit 90a.

This is because the skin current on the surface of the circular conductor plate 90 due to the microwaves propagating in the direction parallel to the slit 90a, that is, the radial direction of the circular conductor plate 90, flows in the direction parallel to the slit, so that the influence of the slit is not exerted. On the contrary, the direction perpendicular to the slit, that is, the circular conductor plate 9
Circular conductor plate 9 by microwaves propagating in the direction of rotation 0
Since the skin current on the surface of 0 flows in the direction perpendicular to the slit, the slit acts as a series impedance. That is, since the direction of the high-frequency current is limited by the slit 90a and the propagation constant does not change for the microwave propagating in the radial direction of the gap portion, it acts as a series impedance for the microwave in the rotating direction. Increase the propagation constant. Therefore, due to the action of the series impedance, the microwave propagating in the circumferential direction of the circular conductor plate 90 is blocked or the phase constant is changed to cause resonance (the electrical length in the circumferential direction of the circular conductor plate 90 approaches an integral multiple of the wavelength. And a resonance phenomenon occurs). As a result, it is possible to reduce the electric field strength in the gap portion, and consequently suppress the discharge in the gap portion.

When the end portion of the circular conductor plate is bent to increase the strength, the gap between the end portion of the circular conductor plate and the waveguide wall is partially narrowed, and the gap in the rotation direction is increased. The operation is similar to that of a ridge waveguide, the wavelength shortening effect appears, the difference between the electrical length and the physical length increases, and the possibility of resonance in the rotation direction increasing even when the physical length deviates from the resonance condition. However, even in such a case, by providing the slit 90a as shown in FIG. 1 of the present invention, the resonance condition can be removed.

FIG. 2 is a perspective view of a waveguide wall 21 applied to a waveguide switching device for a high frequency heating apparatus according to another embodiment of the present invention. The waveguide switching device for a high frequency heating device to which the waveguide wall 21 is applied has the same structure as that shown in FIGS. 7 and 8, and the waveguide for a high frequency heating device shown in FIGS. The only difference is that the waveguide wall 21 is used in place of the waveguide walls 22, 23 (FIG. 8) in the pipe switch.

The waveguide wall 21 of this embodiment shown in FIG. 2 has a plurality of slits 21a radially formed at predetermined intervals. When the waveguide wall 21 in which the plurality of slits 21a are radially formed is used instead of the waveguide walls 22 and 23 in the waveguide switching device for the high frequency heating device shown in FIGS. Plural slits 2 on the tube wall 21
1a acts in the same manner as in the embodiment shown in FIG. 1 to reduce the electric field strength in the gap portion, thereby preventing the danger of discharge.

Further, the slit 21 provided in the waveguide wall 21
a acts as a slit not only on the gap portion but also on the cavity portion of the high-frequency heating device waveguide switching device configured as shown in FIGS. 7 and 8, and also for the microwave of the cavity portion, It acts so as to propagate only in the radial direction. Therefore, the slit 21a shown in FIG. 2 corresponds to the slit 9 shown in FIG.
The effect is greater than 0a.

FIG. 3 is a perspective view of a circular conductor plate 91 applied to a waveguide switching device for a high frequency heating apparatus according to still another embodiment of the present invention. The waveguide switching device for a high frequency heating device to which the circular conductor plate 91 is applied has the same structure as that shown in FIGS. 7 and 8, and the waveguide switching device for a high frequency heating device shown in FIGS. The only difference is that the circular conductor plate 91 is used instead of the circular conductor plate 9 in the switch.

The circular conductor plate 91 of this embodiment shown in FIG.
A plurality of protrusions 91a are formed at predetermined intervals in the circumferential direction,
The height of the gap between the conductor plate 91 and the waveguide wall facing the conductor plate is periodically changed by the plurality of protrusions 91a in the rotating direction of the conductor plate. is there. The protruding portion 91a is formed on the gap portion side.

By using the circular conductor plate 91 having the plurality of protrusions 91a formed in this manner in place of the circular conductor plate 9 in the waveguide switching device for the high frequency heating device shown in FIGS. The portion 91a can act as a stub in the radial direction and as a stop band filter in the rotational direction. In particular, when the protrusion 91a is formed to be long in the radial direction, the protrusion 91a operates in the same manner as a ridge waveguide with respect to microwaves propagating in the radial direction, shortens the wavelength, and reduces the circular conductor plate. The radius of 91 can be further reduced. Further, the microwave propagating in the rotation direction can be blocked by appropriately selecting the height and width of the protruding portion 91a. In this way,
It is possible to reduce the electric field strength in the gap portion and avoid the risk of discharge.

FIG. 4 is a cross-sectional view showing the protrusion 91a shown in FIG. 3 formed by pressing (squeezing). As shown in the figure, by forming the protrusion 91a by press working, it is possible to manufacture at low cost.

FIG. 5 is a perspective view of a dielectric plate 31 applied to a waveguide switching device for a high frequency heating apparatus according to another embodiment of the present invention. The waveguide switching device for a high-frequency heating device to which the dielectric plate 31 shown in the same figure has the same structure as that shown in FIGS. 7 and 8, and is for the high-frequency heating device shown in FIGS. The only difference is that the dielectric plate 31 is provided between the circular conductor plate 9 and the waveguide walls 22 and 23 facing the circular conductor plate in the waveguide switching device.

In the dielectric plate 31 of this embodiment shown in FIG. 5, a plurality of openings 31a are formed at predetermined intervals in the circumferential direction, and the circular conductor plate 9 and the circular conductor plate 9 are formed by the plurality of openings 31a. The height of the gap between the waveguide walls 22 and 23 facing each other is periodically changed in the rotation direction of the circular conductor plate.

The dielectric plate 31 having the plurality of openings 31a formed in this manner is used for the circular conductor plate 9 and the waveguide walls 22 and 23 in the waveguide switching device for the high-frequency heating device shown in FIGS. By providing the gap between the openings 31a, a protrusion is formed by the dielectric between the openings 31a, so that the electric field strength of the gap is reduced as in the embodiment shown in FIG. 3, thereby preventing the risk of discharge. can do.

The dielectric plate 31 is a pair of circular conductor plates 9
Alternatively, it may be simply provided so as to be sandwiched between the waveguide walls 22 and 23, may be adhered to the circular conductor plate 9, or may be adhered to the waveguide wall, or may be a dielectric material. Two plates 31 may be provided and each dielectric plate 31 may be bonded to both the circular conductor plate 9 and the waveguide walls 22 and 23.

Further, the dielectric plate 31 is designed such that the height of the protruding portion of the dielectric between the openings 31a is the same as the height of the gap portion, and the dielectric material is made of a slippery material such as Teflon. By doing so, the gap portion can also serve as a spacer, and the processing of the gap portion can be facilitated.

FIG. 6 is a perspective view showing another dielectric plate 32 obtained by cutting off the peripheral edge of the dielectric plate 31 shown in FIG.
The dielectric plate 32 having the peripheral edge removed in this manner can also function in exactly the same manner as the dielectric plate 31 shown in FIG.

[0039]

As described above, according to the present invention,
A conductor plate is formed by forming radial slits in the conductor plate, forming radial slits in the wall portion of the waveguide facing the conductor plate, or forming protrusions periodically in the circumferential direction of the conductor plate. And periodically changing the height of the gap between the wall of the waveguide facing the conductor plate in the rotating direction of the conductor plate,
Alternatively, a dielectric plate having openings formed periodically in the same direction as the circumferential direction of the conductor plate is provided between the conductor plate and a wall portion of the waveguide opposite to the conductor plate, and the conductor plate and the conductor are provided. The height of the gap between the plate and the wall of the waveguide opposite to the plate is periodically changed in the rotating direction of the conductor plate, so that the gap between the conductor plate and the waveguide wall enters the gap. Since the wave traveling direction is limited to the radial direction only, the resonance condition is not satisfied, the electric field strength in the gap portion can be reduced, discharge can be suppressed, and safety and reliability can be improved. Since the electrical length of the gap at the end of the conductor plate in the rotation direction can be changed, the size of the waveguide can be arbitrarily selected, and the size can be reduced.

[Brief description of drawings]

FIG. 1 is a perspective view of a circular conductor plate used in a waveguide switching device for a high-frequency heating device according to an embodiment of the present invention.

FIG. 2 is a perspective view of a waveguide wall applied to a waveguide switching device for a high-frequency heating device according to another embodiment of the present invention.

FIG. 3 is a perspective view of a circular conductor plate applied to a waveguide switching device for a high-frequency heating device according to still another embodiment of the present invention.

FIG. 4 is a press process (squeezing process) for the protrusion shown in FIG.
It is sectional drawing which shows what was formed by.

FIG. 5 is a perspective view of a dielectric plate applied to a waveguide switching device for a high-frequency heating device according to another embodiment of the present invention.

6 is a perspective view showing another dielectric plate obtained by cutting off the peripheral edge of the dielectric plate shown in FIG. 5. FIG.

7A and 7B are a plan view and a cross-sectional view showing a configuration of a waveguide switching device for a high-frequency heating device.

8 is an exploded perspective view showing a configuration of a main part of the waveguide switching device for the high-frequency heating device shown in FIG.

[Explanation of symbols]

 1, 5 and 7 Waveguide 3 Waveguide switch 9 Pair of circular conductor plates 11 Rotating shaft 13 First conductor 15 Choke structure 21 Waveguide wall 21a, 90a Slit 31, 32 Dielectric plate 31a Opening 90 , 91 circular conductor plate 91a protrusion

Claims (5)

[Claims] 1. A pair of rotatably opposed conductor plates, which are parallel to the H-plane and share a rotation axis, are provided at waveguide branch points sharing the H-plane, which is a plane in which long sides of a rectangular waveguide cross section are in contact. By setting a conductor vertically provided between the pair of conductor plates in front of the waveguide, the waveguide is blocked, and a choke structure is provided in a gap on the H surface of the waveguide facing the conductor plate. A waveguide switching device for a high-frequency heating device according to claim 1, wherein radial slits are formed in the conductor plate. 2. A pair of rotatably opposed conductor plates, which are parallel to the H-plane and share a rotation axis, are provided at waveguide branch points sharing the H-plane, which is the plane where the long sides of the rectangular waveguide cross section are in contact. By setting a conductor vertically provided between the pair of conductor plates in front of the waveguide, the waveguide is blocked, and a choke structure is provided in a gap on the H surface of the waveguide facing the conductor plate. A waveguide switch for a high-frequency heating device, wherein a radial slit is formed in a wall portion of the waveguide facing the conductor plate. 3. A pair of rotatably opposed conductor plates, which are parallel to the H plane and share a rotation axis, are provided at waveguide branch points sharing the H plane, which is a plane where the long sides of the rectangular waveguide cross section contact. By setting a conductor vertically provided between the pair of conductor plates in front of the waveguide, the waveguide is blocked, and a choke structure is provided in a gap on the H surface of the waveguide facing the conductor plate. In the waveguide switching device for a high-frequency heating device, the height of the gap between the conductor plate and the wall portion of the waveguide facing the conductor plate is periodically adjusted in the rotation direction of the conductor plate. 1. A waveguide switching device for a high-frequency heating device, comprising: a protruding portion which is periodically formed in a circumferential direction of the conductor plate so as to be changed. 4. The waveguide switching device for a high frequency heating apparatus according to claim 3, wherein the protrusion is formed by press-squeezing. 5. A pair of rotatably opposed conductor plates that are parallel to the H-plane and share a rotation axis are provided at waveguide branch points that share the H-plane, which is the plane where the long sides of the rectangular waveguide cross section contact. By setting a conductor vertically provided between the pair of conductor plates in front of the waveguide, the waveguide is blocked, and a choke structure is provided in a gap on the H surface of the waveguide facing the conductor plate. In the waveguide switching device for a high-frequency heating device, the height of the gap between the conductor plate and the wall portion of the waveguide facing the conductor plate is periodically adjusted in the rotation direction of the conductor plate. A dielectric plate having openings formed periodically in the same direction as the circumferential direction of the conductor plate is provided between the conductor plate and the wall portion of the waveguide facing the conductor plate. A waveguide switching device for a high-frequency heating device, characterized in that