JPS6211475B2 - - Google Patents

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Publication number
JPS6211475B2
JPS6211475B2 JP56151867A JP15186781A JPS6211475B2 JP S6211475 B2 JPS6211475 B2 JP S6211475B2 JP 56151867 A JP56151867 A JP 56151867A JP 15186781 A JP15186781 A JP 15186781A JP S6211475 B2 JPS6211475 B2 JP S6211475B2
Authority
JP
Japan
Prior art keywords
groove
radio wave
heating chamber
chiyoke
harmonic
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
JP56151867A
Other languages
Japanese (ja)
Other versions
JPS5853180A (en
Inventor
Yasushi Iwabuchi
Tadashi Funamizu
Tetsuo Kubota
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hitachi Netsu Kigu KK
Original Assignee
Hitachi Netsu Kigu KK
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hitachi Netsu Kigu KK filed Critical Hitachi Netsu Kigu KK
Priority to JP15186781A priority Critical patent/JPS5853180A/en
Priority to GB08224298A priority patent/GB2106360B/en
Priority to US06/410,956 priority patent/US4475023A/en
Priority to CA000410083A priority patent/CA1184616A/en
Publication of JPS5853180A publication Critical patent/JPS5853180A/en
Publication of JPS6211475B2 publication Critical patent/JPS6211475B2/ja
Granted legal-status Critical Current

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Description

【発明の詳細な説明】[Detailed description of the invention]

本発明は高周波エネルギーによつて食品などの
被加熱物を加熱処理するもので電波漏洩防止用チ
ヨーク溝を備えた高周波加熱装置に関するもので
ある。 近時、IC、マイコンなど小形で多機能を持つ
電子部品が高周波加熱装置の制御回路に積極的に
とり入れられ、操作パネルの小形化、薄形化が進
んでおり、こういつた操作パネルと釣合のとれた
薄形ドアが要望されている。また複雑な操作を自
動化する傾向が多くなつており、電子回路関係に
コストが掛かるようになつてきているので、機械
部品特にドア機構の低コスト化が要望されてい
る。 それらの高周波加熱装置のドアとしては、チヨ
ーク溝と電波吸収材のフエライトを併用したもの
が多いが、フエライトをドア全周にとりつけるた
めコストが高いものであつた。さらにチヨーク溝
自体の減衰効果を増し、フエライトを除去しよう
とする提案がなされている。 この提案は次に述べる通りである。 使用波長λの1/4の深さを持つチヨーク溝の一面 をλ/4の長さの導体片、いわゆるスリツトを周期的 に並べた電波伝搬方向規制装置として使いチヨー
ク溝の減衰効果を増す提案が米国特許27772402
(1956.11.27特許)、同2850706(1958.9.2特許)に
おいてなされている。上記特許と同様な電波漏洩
防止構造が同3767884(日本特開昭48―81146、日
本特公昭53―4660)に提案されているが、この提
案ではスリツト(スロツト)がチヨーク溝に入る
前の電波伝搬経路の一面となつており、スリツト
と対向する金属面との間隔を誘電体を充てんする
ことにより強制的にとつているものである。これ
はスリツトが部分的に対向金属面と接触すると実
質的にスリツトの長さがλ/4より短かくなり、電波 伝搬方向規制装置(電磁エネルギーモード維持構
造物)としての作用が低下するためである。この
ものではドアと加熱室開口部周縁の隙間に入射す
る電波が多くなり、基本波および高周波の漏洩を
防止するには導電性ゴムを追加したり、漏洩電波
の伝搬経路を複雑にして大きな減衰効果を出す必
要があり、ドアの薄形化、低コスト化には不向き
である。 また、約λ/4のスリツトを有する金属壁でチヨー ク溝を二つに分割して減衰効果を増すことが英国
特許1392498、日本特公昭51―22663等多数提案さ
れているが、これらでは実質的にチヨーク溝が大
形化し、ドアの薄形化、低コスト化には不向きで
ある。 さらに、チヨーク溝内に上記のようなスリツト
でない別の周期構造体を入れたものが、日本特公
昭54―21574、日本特公昭52―40461に提案されて
いるが、チヨーク溝を形成する面そのものでなく
別のものを追加する必要があり、さらに高調波に
対しては考慮されていないので、実用にするため
にはフエライト等の追加も必要となり、コスト的
に不利である。 なお、ドア周縁部に金属製の爪状体を所定間隔
ごとに設けたものが、日本特開昭55―41679に提
案されている。周知のようにチヨーク部の入口は
電界最大位置となるが、この電界最大位置におい
て、加熱室開口端縁部に金属接触するシーラ板の
端部切口と上記爪状体の三角形状の先端切口とが
対向しているので局部的に著しい電磁界集中が起
こり、チヨーク部の入口付近でスパークや異常加
熱が発生し易い。また、チヨーク部に必要な長さ
である電波の1/4波長を加熱室開口端縁部と平行
方向のみにとる構成であるため、チヨーク部寸法
が大きくなり、ドアの小形化には不向きである。 上記のように従来のドアは小形化、薄形化、低
コスト化には不向きであつた。 そこで、本発明は基本波用チヨーク溝と高周波
用チヨーク溝とを逆向きに対向させて、一つの入
口を持つ一つの電波減衰空胴をドアの周縁に設
け、高調波用チヨーク溝の壁面自体を複数の波板
に分割し、この波板の形状、寸法に特定の関係を
与えることにより、基本波および高調波に対する
電波漏洩を極力押えるというように簡単な電波漏
洩防止構造を持ち、小形化、薄形化、低コスト化
がはかれるドアを備えた高周波加熱装置を提供す
ることを目的とする。 次に本発明の一実施例を図面とともに説明す
る。 第1図は本発明の高周波加熱装置の一例を示す
外観図である。1は外箱で、2はドア、3はドア
2の厚さと釣合のとれた厚みの操作パネルであ
る。操作パネル3は用途によつて種々様々に変え
られるが、自動加熱の場合を例にして説明する。
4は高周波出力、残存加熱時間などを示す表示装
置、5はメニユーごとの最適加熱パターンを決め
るメニユー選定ボタン、6は仕上りの程度を好み
に合わせて選ぶ仕上り調節つまみ、7は加熱を開
始するときに押す加熱ボタン、8はドアを開ける
ためのドア開ボタンである。 第2図は第1図に対応する本発明の高周波加熱
装置の要部断面図である。9は高周波エネルギー
を発生する高周波発振器で、10は高周波発振器
9からの高周波エネルギーを加熱室11に伝送す
るための導波管である。12は均一加熱を行なう
ためのターンテーブルで、この上に被加熱物を置
く。均一加熱装置としてはターンテーブル12以
外にもスターラ、回転アンテナ、固定アンテナな
どがあり、いずれを用いてもよい。13はドア2
の前面に取付けられた透明板で、透明板13はド
アカバー14によつてドア前板15に固着されて
いる。ドア前板15にはドア後板16がネジ17
によつて取付けられている。ドア前板15とドア
後板16とはともに金属板から成り、加熱室11
の開口部周縁18に対向した電波減衰空胴19を
形成する。20は加熱室11に面した透明板で、
21は金網(あるいは穴あき金属板)である。透
明板13、金網21および透明板20を通して加
熱室11が覗けるようになつている。22はドア
2をとり囲むサツシである。 第3図は第2図で示した電波減衰空胴19付近
の拡大図である。誘電加熱周波数たとえば2450M
Hzに対する電波漏洩を防止するための基本波用チ
ヨーク溝19aと上記周波数の第2高調波4900M
Hzに対する電波漏洩を防止するための第2高調波
用チヨーク溝19bを互いに逆向きに対向させ
て、一つの入口23を持つ一つの電波減衰空胴1
9を形成している。基本波用チヨーク溝19aで
は入口23から短絡面15aまでのL字形の電波
伝搬経路を誘電加熱周波数の自由空間波長λoに
対して約λo/4としている。基本波用チヨーク溝1 9aを加熱室11に近い側に配置すると共にこの
溝19aの一壁面16aを加熱室開口部周縁18
との接触面としている。第2高調波用チヨーク溝
19bでは入口23から短絡面15bまでのL字
形の電波伝搬経路を約λo/8としている。第2高調 波用チヨーク溝19bの壁面15cを第6図に示
すように複数の台形状の波板15wに分割し、こ
の波板15wには先端15w′を電波減衰空洞1
9の内部に向かつて折り曲げた先端面15Tを設
け、この先端面15Tとほぼ平行に対向するよう
に基本波用チヨーク溝19aの一壁面16aの端
部にも折り曲げ面16Tを設け、基本波用チヨー
ク溝19aおよび第2高調波用チヨーク溝19b
を共に加熱室開口部周縁18に対して直角方向と
平行方向から成るL字形の電波伝搬経路を形成し
ている。第7図に示すように、隣り合う先端面1
9T間の空隙寸法Bを電波減衰空洞19の入口寸
法Aより大きくしている。 次に、本発明の高周波加熱装置の作用を説明す
る。 第4図、第5図および第6図は第2高調波用チ
ヨーク溝の壁面15c自体を整合ポスト24,2
5を変形して波板15wとした過程を説明するも
のである。第4図の電波減衰空胴19の入口23
には導体丸棒24すなわちマイクロ波理論で整合
素子として知られている整合ポストが複数個配置
されている。導体丸棒24の長さ、直径、間隔な
どを適当に選ぶことにより、外部に漏洩しようと
する電波を能率よく電波減衰空胴19内に導き入
れることができる。さらに、第3図で示したよう
に電波減衰空胴19内の2方向の電波伝搬経路長
を約λo/4とλo/8にすることにより基本波および
第2 高調波に対してそれぞれ入口23で高インピーダ
ンスを生じさせることができる。一部の電波は電
波減衰空胴19の入口23を通過して外部へ漏洩
する。この外部へ漏洩する電波を少なくするには
導体丸棒24と加熱室開口部周縁18との平均的
な導体表面間距離を小さくして両導体24,18
間を低インピンダンスとし、上記口23の高イン
ピーダンスとの間の反射を大きくする必要があ
る。この点では、第4図の導体丸棒24よりも第
5図のように導体角棒25の方が適している。し
かし、導体角棒25を多数並べて第2高調波用チ
ヨーク溝19bの一壁面を形成すると、第2高調
波チヨーク溝19b内の空間容積が導体角棒25
の容積の分だけ小さくなるので共振のQが小さく
なり減衰効果の点で不利となる。 そこで、本発明では、導体丸棒24や導体角棒
25の上記有効な作用を保持し、欠点のみ除去し
た整合ポストとして働くものとして第6図、第7
図に示した波板15wを用いている。第7図及び
つぎの表により電波減衰空胴19の入口23付近
での波板15wの作用を説明する。 λo:自由空間波長(2450MHzのとき122.3mm) m:各モードのx方向の電界最大点の数 しや断波長(x方向の波長)λc=2a/m 管内波長(z方向の波長) x方向の電界最大位置xnax=Na/2m(N=1,3
, 2m−1)
The present invention relates to a high-frequency heating device for heating an object such as food using high-frequency energy, and is provided with a chiyoke groove for preventing leakage of radio waves. In recent years, small, multifunctional electronic components such as ICs and microcomputers have been actively incorporated into the control circuits of high-frequency heating equipment, and operation panels have become smaller and thinner. A well-fitting, thin door is desired. Furthermore, there is a growing tendency to automate complex operations, and as electronic circuits become more expensive, there is a demand for lower costs for mechanical parts, especially door mechanisms. Many of the doors of these high-frequency heating devices use a combination of a chiyoke groove and ferrite, which is a radio wave absorbing material, but the cost is high because the ferrite is attached to the entire circumference of the door. Furthermore, proposals have been made to increase the damping effect of the chiyoke groove itself and to remove ferrite. This proposal is as follows. A proposal to increase the attenuation effect of the chiyoke groove by using one side of the chiyoke groove, which has a depth of 1/4 of the used wavelength λ, as a radio wave propagation direction regulating device in which λ/4 length conductor pieces, so-called slits, are arranged periodically. is US Patent 27772402
(1956.11.27 patent) and 2850706 (1958.9.2 patent). A radio wave leakage prevention structure similar to the above patent was proposed in 3767884 (Japanese Patent Publication No. 48-81146, Japanese Patent Publication Publication No. 53-4660), but in this proposal, the radio wave leakage prevention structure is This is one surface of the propagation path, and the distance between the slit and the opposing metal surface is forcibly maintained by filling it with a dielectric. This is because when the slit partially contacts the opposing metal surface, the length of the slit becomes substantially shorter than λ/4, and its function as a radio wave propagation direction regulating device (electromagnetic energy mode sustaining structure) decreases. be. With this type, many radio waves enter the gap between the door and the heating chamber opening, and to prevent leakage of fundamental waves and high frequencies, it is necessary to add conductive rubber or to complicate the propagation path of the leaked radio waves, resulting in large attenuation. It is necessary to produce an effect, and it is not suitable for making doors thinner and lowering costs. In addition, many proposals have been made, such as British Patent No. 1392498 and Japanese Patent Publication No. 1972-22663, to increase the damping effect by dividing the cheese yoke groove into two with a metal wall having a slit of about λ/4. The yoke groove becomes large, making it unsuitable for making doors thinner and lower in cost. Furthermore, a structure in which a periodic structure other than the above-mentioned slits is inserted into the chiyoke groove has been proposed in Japanese Patent Publication No. 54-21574 and Japanese Patent Publication Publication No. 52-40461, but the surface forming the chiyoke groove itself Moreover, since harmonics are not taken into account, it is also necessary to add ferrite etc. for practical use, which is disadvantageous in terms of cost. Note that a door in which metal claw-like bodies are provided at predetermined intervals on the periphery of the door has been proposed in Japanese Patent Application Laid-open No. 41679/1983. As is well known, the electric field is at the maximum position at the entrance of the cheese yoke, and at this position, the end cut of the sealer plate that makes metal contact with the opening edge of the heating chamber and the triangular tip cut of the claw-shaped body Since they are facing each other, significant electromagnetic field concentration occurs locally, and sparks and abnormal heating are likely to occur near the entrance of the choke section. In addition, since the configuration is such that the 1/4 wavelength of the radio waves, which is the length required for the front yoke, is taken only in the direction parallel to the opening edge of the heating chamber, the size of the yoke becomes large, making it unsuitable for downsizing the door. be. As mentioned above, conventional doors are not suitable for miniaturization, thinning, and cost reduction. Therefore, in the present invention, the fundamental wave channel groove and the high frequency channel channel are opposed in opposite directions, and one radio wave attenuation cavity with one entrance is provided at the periphery of the door, and the wall surface of the harmonic channel channel itself. By dividing the wave plate into multiple corrugated plates and giving a specific relationship to the shape and dimensions of the corrugated plates, it has a simple radio wave leakage prevention structure that suppresses radio wave leakage to the fundamental wave and harmonics as much as possible, making it more compact. An object of the present invention is to provide a high-frequency heating device equipped with a door that can be made thinner and lower in cost. Next, one embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an external view showing an example of the high frequency heating device of the present invention. 1 is an outer box, 2 is a door, and 3 is an operation panel whose thickness is balanced with the thickness of the door 2. Although the operation panel 3 can be changed in various ways depending on the application, the case of automatic heating will be explained as an example.
4 is a display device that shows high frequency output, remaining heating time, etc., 5 is a menu selection button that determines the optimal heating pattern for each menu, 6 is a finish adjustment knob that allows you to select the degree of finish according to your preference, and 7 is when to start heating. 8 is the heating button to press, and 8 is the door open button to open the door. FIG. 2 is a sectional view of a main part of the high-frequency heating device of the present invention corresponding to FIG. 1. 9 is a high frequency oscillator that generates high frequency energy, and 10 is a waveguide for transmitting the high frequency energy from the high frequency oscillator 9 to the heating chamber 11. 12 is a turntable for uniform heating, on which the object to be heated is placed. In addition to the turntable 12, the uniform heating device includes a stirrer, a rotating antenna, a fixed antenna, etc., and any of them may be used. 13 is door 2
The transparent plate 13 is fixed to the door front plate 15 by a door cover 14. The door front plate 15 is attached to the door rear plate 16 with screws 17.
installed by. Both the door front plate 15 and the door rear plate 16 are made of metal plates, and the heating chamber 11
A radio wave attenuation cavity 19 is formed opposite the opening periphery 18 of the opening. 20 is a transparent plate facing the heating chamber 11;
21 is a wire mesh (or perforated metal plate). The heating chamber 11 can be seen through the transparent plate 13, the wire mesh 21, and the transparent plate 20. 22 is a sash surrounding the door 2. FIG. 3 is an enlarged view of the vicinity of the radio wave attenuation cavity 19 shown in FIG. Dielectric heating frequency for example 2450M
Fundamental wave groove 19a to prevent radio wave leakage at Hz and second harmonic of the above frequency 4900M
One radio wave attenuation cavity 1 having one inlet 23 with second harmonic channel grooves 19b facing each other in opposite directions to prevent radio wave leakage for Hz.
9 is formed. In the fundamental wave channel groove 19a, the L-shaped radio wave propagation path from the inlet 23 to the short-circuit surface 15a is approximately λo/4 with respect to the free space wavelength λo of the dielectric heating frequency. The fundamental wave channel groove 1 9a is arranged on the side closer to the heating chamber 11, and one wall surface 16a of this groove 19a is connected to the heating chamber opening periphery 18.
This is the contact surface with the In the second harmonic channel groove 19b, the L-shaped radio wave propagation path from the inlet 23 to the shorting surface 15b is approximately λo/8. The wall surface 15c of the second harmonic channel groove 19b is divided into a plurality of trapezoidal corrugated plates 15w as shown in FIG.
A bent end surface 15T is provided inside the groove 9, and a bent surface 16T is also provided at the end of one wall surface 16a of the fundamental wave chiyoke groove 19a so as to face the end surface 15T substantially parallel to the end surface 15T. Chiyoke groove 19a and second harmonic chiyoke groove 19b
Together, they form an L-shaped radio wave propagation path consisting of directions perpendicular and parallel to the heating chamber opening periphery 18. As shown in FIG. 7, adjacent tip surfaces 1
The gap dimension B between 9T is made larger than the entrance dimension A of the radio wave attenuation cavity 19. Next, the operation of the high frequency heating device of the present invention will be explained. 4, 5 and 6, the wall surface 15c of the second harmonic chiyoke groove itself is connected to the alignment posts 24, 2.
5 to explain the process of transforming the corrugated plate 15w. Entrance 23 of the radio wave attenuation cavity 19 in FIG.
A plurality of conductor round bars 24, that is, matching posts known as matching elements in microwave theory, are arranged. By appropriately selecting the length, diameter, spacing, etc. of the conductor round rods 24, radio waves that would otherwise leak to the outside can be efficiently introduced into the radio wave attenuation cavity 19. Furthermore, as shown in FIG. 3, by setting the radio wave propagation path lengths in two directions in the radio wave attenuation cavity 19 to approximately λo/4 and λo/8, the entrance 23 is provided for the fundamental wave and the second harmonic, respectively. can produce high impedance. Some of the radio waves pass through the entrance 23 of the radio wave attenuation cavity 19 and leak to the outside. In order to reduce the radio waves leaking to the outside, the average distance between the conductor surfaces of the conductor round bar 24 and the heating chamber opening periphery 18 is made small.
It is necessary to have a low impedance between the openings 23 and the high impedance of the opening 23, and to increase the reflection between the openings 23 and the high impedances. In this respect, the square conductor bar 25 shown in FIG. 5 is more suitable than the round conductor bar 24 shown in FIG. However, if a large number of square conductor bars 25 are arranged to form one wall surface of the second harmonic channel groove 19b, the space volume inside the second harmonic channel groove 19b becomes smaller than the square conductor bars 25.
Since the Q of resonance is reduced by the volume of , the Q of resonance becomes small, which is disadvantageous in terms of damping effect. Therefore, in the present invention, the conductor round bar 24 and the conductor square bar 25 have the above-mentioned effective functions and work as alignment posts with only the defects removed, as shown in FIGS. 6 and 7.
The corrugated plate 15w shown in the figure is used. The action of the corrugated plate 15w near the entrance 23 of the radio wave attenuation cavity 19 will be explained with reference to FIG. 7 and the following table. λo: Free space wavelength (122.3 mm at 2450 MHz) m: Cutoff wavelength of the maximum point of the electric field in the x direction of each mode (wavelength in the x direction) λc = 2a/m Inner wavelength (wavelength in the z direction) Maximum position of electric field in x direction x nax = Na/2m (N=1,3
, 2m−1)

【表】 加熱室11から外部へ漏洩しようとする電波は
一般に加熱室開口部周縁18とドア2との接触部
の長手方向(x方向)にいくつかの電界最大点E
naxを持つ高次モードである。例えば、365×260
mmの開口を持つ加熱室11の場合、表に示すよう
に電波の漏洩方向に対応するz方向を伝搬方向と
する導波管内を2450MHzの電波が伝搬すると想定
してみる。この場合、長手方向の寸法aが365mm
に対してはTE10〜TE50までの5種の高次モード
が伝搬可能であり、aが260mmに対してはTE10
TE40までの4種の高次モードが伝搬可能であ
る。電界最大点Enaxの総数はaが365mmに対して
13で、aが260mmに対して10である。加熱室11
内にはターンテーブル12あるいは回転アンテナ
等の電界撹拌装置が加熱むらを少なくするために
設けられ、電界最大点Enaxが時間と共に変化し
ている。さらに、どの高次モードが漏洩電波とし
てz方向に侵入してくるかは加熱室11内の共振
モード、導波管10の結合位置、負荷の位置や
量、高周波発振器の動作点等の種々の要因に左右
され、解析は困難である。整合ポストとしての波
板15wは電界最大位置xnaxに設けるのが最も
効果的である。しかし、上記のように実際にはそ
の位置が流動的である。そこで等間隔に置くこと
にすると、あらゆる高次モードの各電界最大位置
naxに波板15w対応させるためには、加熱室
11の開口の長手方向(x方向)が365mmに対し
てはこの長さを電界最大点の総数13で割つた28
mmのピツチ以下で波板15wを並べる必要があ
る。同様にして長手方向(x方向)が260mmに対
しては、この長さを電界最大点の総数10で割つた
26mm以下で波板15wを並べる必要がある。隣り
合う波板15wの間の空隙寸法Bは波板15wの
先端15w′付近において、電波減衰空胴19の
入口寸法Aより大きくとつており、かつ先端15
Tと折り曲げ面16Tとが平面同志で向かい合つ
ているので、波形の先端15w′では第7図のよ
うに電界がz方向に揃えられる。これは、入口2
3において、電波減衰空胴19内へ伝搬するz方
向の電界成分(第7図内の実線矢印)を増し、電
波減衰空胴19内へ伝搬できないx方向の電界成
分(第7図の点線矢印)を減らす作用を波板15
wが持つことを意味する。つまり、波板15wは
加熱室開口部周縁18とドア2との間を漏洩する
あらゆる高次モードの電波を電波減衰空胴19内
に能率よく入れる整合ポストの作用を持ち、外部
へ漏洩する電波を減少させる。さらに、第3図で
示したように電波減衰空胴19内の2方向の電波
伝搬経路長を約λo/4と約λo/8にして基本波およ
び第 2高調波に対してそれぞれ高インピーダンスにし
ている。加熱室開口部周縁18と基本波用チヨー
ク溝19aの壁面16aとがドア2の閉成時に平
面接触するようになつており、実質的に両者の相
互間の間隙は少ないので、この接触部に入り込む
漏洩電波自体も少ない。また、接触部は低インピ
ーダンス(伝送線路としての特性インピーダン
ス)で、上記入口23の高インピーダンスとの反
射が大きいので、波板15wに達する電波も微少
になつている。この微少電波を波板15wの整合
ポストの作用により、電波減衰空胴19内へ能率
よく導き入れ、この空胴19内の空間の蓄積エネ
ルギーとして保持し、一部は壁面での損失電力と
して消費される。 一方、空隙寸法B>入口寸法Aという寸法関係
を保ち、かつ加熱室開口部周縁18に対向する波
板15wの導体面を多くして、両導体間のインピ
ーダンスを低くするために、波形15wは根本1
5w″の幅が広く、先端15w′で幅の狭い台形状
にしている。この両導体間のインピーダンスと上
記入口23の高インピーダンスとの反射を大きく
して、入口23を通過して外部へ向かう漏洩電波
をさらに少なく押えている。 第8図は365×260mmの開口を持つ加熱室11に
2450MHzの周波数で700Wの高周波電力を供給
し、ターンテーブル12に水275mlを入れたビー
カを載せて加熱した場合の電波漏洩量を示す。操
作パネル側において加熱室開口部周縁18と基本
波用チヨーク溝19aの壁面16aとの接触部の
間隙を第8図の横軸のラツチ側ギヤツプとした。
曲線Aは第2高調波用チヨーク溝19bの加熱室
開口部周縁18と対向する壁面15cを従来のス
リツトや上記実施例の整合ポストと等価な波板1
5wのない平面としたいわゆるチヨーク単独の場
合(同図A′で断面斜視図を示す)の電波漏洩特
性である。曲線Bは上記壁面15cにλo/12(10 mm)の長さのスリツトを設けた(同図B′で断面斜
視図を示す)もので、曲線Cは上記壁面15cを
波板15wから構成した(図同C′で断面斜視図
を示す)ものである。第8図から曲線C,曲線
B、曲線Aの順に電波漏洩量が少ないことが明ら
かである。すなわち波板15wを設けたドア2を
備えた高周波加熱装置が最も電波漏洩量が少な
く、フエライトや導電性ゴム等を除去し得るので
低コスト化に適している。 さらに、電波減衰空胴19は第3図で示したよ
うに基本波用チヨーク溝と第2高調波用チヨーク
溝とを互いに逆向きに対向させており、各チヨー
クさらに、電波減衰空洞19は第3図で示したよ
うに基本波用チヨーク溝と第2高調波用チヨーク
溝とを互いに逆向きに対向させており、各チヨー
ク溝におけるL字形の電波伝搬経路長は加熱室開
口部周縁18と平行方向(z方向)と直角方向
(y方向)の長さの和をそれぞれλ/4、λ/8
にしている。したがつて電波減衰空洞19のy方
向およびz方向の寸法が共に小さくできるので、
ドアの小形化、薄形化が図れ、小形化薄形化した
操作パネルと釣合のとれたデザイン上望ましい外
観に仕上げることができる。また、波板15wの
先端面15Tと基本波用チヨーク溝19aの壁面
16a端部の折り曲げ面16Tとが平面同志で向
かい合つているため、電磁界の集中によるスパー
クや異常加熱の発生を防止することができる。 以上のように、本発明によると、L字形の基本
波用チヨーク溝とL字形の第2高調波用チヨーク
溝とを逆向きに対向させた一つの入口を持つ一つ
の電波減衰空洞をドアの周縁に設け、基本波用チ
ヨーク溝を加熱室に近い側に配置すると共にこの
溝の一壁面を加熱室開口部周縁と平面接触させ、
第2高調波用チヨーク溝の加熱室開口部周縁部と
対向する壁面を先端を折り曲げた複数の台形状の
波板に分割し、かつこの波板間の空隙寸法を電波
減衰空洞の入口寸法より大きくすることにより簡
単な構成で電波漏洩を少なくし、スパークや異常
加熱の発生もなく、かつ小形化、薄形化、低コス
ト化に適するドアを備えた高周波加熱装置を提供
することができる。
[Table] Radio waves that are about to leak from the heating chamber 11 to the outside generally occur at several electric field maximum points E in the longitudinal direction (x direction) of the contact area between the heating chamber opening periphery 18 and the door 2.
It is a higher order mode with nax . For example, 365×260
In the case of the heating chamber 11 having an opening of mm, it is assumed that a 2450 MHz radio wave propagates in a waveguide whose propagation direction is the z direction corresponding to the leakage direction of the radio wave, as shown in the table. In this case, the longitudinal dimension a is 365mm
For a of 260 mm, five higher-order modes from TE 10 to TE 50 can propagate, and for a of 260 mm, TE 10 to TE 50 can be propagated.
Four higher order modes up to TE 40 can be propagated. The total number of electric field maximum points E nax is for a of 365 mm.
13, and a is 10 for 260 mm. Heating chamber 11
Inside, an electric field stirring device such as a turntable 12 or a rotating antenna is provided to reduce uneven heating, and the electric field maximum point E nax changes with time. Furthermore, which higher-order mode enters in the z direction as a leakage radio wave depends on various factors such as the resonance mode in the heating chamber 11, the coupling position of the waveguide 10, the position and amount of the load, and the operating point of the high-frequency oscillator. It depends on many factors and is difficult to analyze. It is most effective to provide the corrugated plate 15w as an alignment post at the maximum electric field position x nax . However, as mentioned above, its position is actually in flux. Therefore, if we decide to place them at equal intervals, in order to correspond to the corrugated plate 15w at each maximum electric field position x nax of all higher-order modes, the longitudinal direction (x direction) of the opening of the heating chamber 11 is 365 mm, so this length is required. 28 divided by the total number of maximum electric field points 13
It is necessary to arrange the corrugated plates 15w at a pitch of mm or less. Similarly, if the longitudinal direction (x direction) is 260 mm, divide this length by the total number of maximum electric field points, 10.
It is necessary to line up corrugated sheets 15W with a width of 26mm or less. The gap dimension B between adjacent corrugated plates 15w is larger than the entrance dimension A of the radio wave attenuation cavity 19 near the tip 15w' of the corrugated plate 15w, and
Since T and the bending surface 16T face each other on a plane, the electric field is aligned in the z direction at the tip 15w' of the waveform as shown in FIG. This is entrance 2
3, the electric field component in the z direction (solid line arrow in FIG. 7) that propagates into the radio wave attenuation cavity 19 is increased, and the electric field component in the x direction that cannot propagate into the radio wave attenuation cavity 19 (dotted line arrow in FIG. 7) is increased. ) to reduce the effect of corrugated plate 15
It means that w has. In other words, the corrugated plate 15w has the function of a matching post that efficiently introduces all high-order mode radio waves leaking between the heating chamber opening periphery 18 and the door 2 into the radio wave attenuation cavity 19, and the radio waves leaking to the outside. decrease. Furthermore, as shown in FIG. 3, the radio wave propagation path lengths in the two directions within the radio wave attenuation cavity 19 are set to approximately λo/4 and approximately λo/8, respectively, to provide high impedance for the fundamental wave and the second harmonic. ing. The heating chamber opening periphery 18 and the wall surface 16a of the fundamental wave cheese yoke groove 19a come into plane contact when the door 2 is closed, and since there is substantially little gap between them, this contact portion There are also fewer leakage radio waves entering. Further, since the contact portion has a low impedance (characteristic impedance as a transmission line) and is largely reflected from the high impedance of the inlet 23, the radio waves reaching the corrugated plate 15w are also very small. This minute radio wave is efficiently introduced into the radio wave attenuation cavity 19 by the action of the matching post of the corrugated plate 15w, and is retained as energy stored in the space inside this cavity 19, and a part of it is consumed as power loss on the wall surface. be done. On the other hand, in order to maintain the dimensional relationship of gap dimension B>inlet dimension A and increase the conductor surface of the corrugated plate 15w facing the heating chamber opening periphery 18 to lower the impedance between both conductors, the waveform 15w is Root 1
It has a trapezoidal shape with a wide width of 5w'' and a narrow width at the tip 15w'.The reflection between the impedance between these two conductors and the high impedance of the entrance 23 is increased, and the conductor passes through the entrance 23 and goes to the outside. This further suppresses leakage radio waves. Figure 8 shows a heating chamber 11 with an opening of 365 x 260 mm.
The amount of radio wave leakage is shown when 700 W of high frequency power is supplied at a frequency of 2450 MHz and a beaker containing 275 ml of water is placed on the turntable 12 and heated. On the operation panel side, the gap between the contact area between the heating chamber opening periphery 18 and the wall surface 16a of the fundamental wave chain yoke groove 19a is defined as the latch side gap on the horizontal axis in FIG.
Curve A indicates that the wall surface 15c of the second harmonic cheese yoke groove 19b facing the heating chamber opening periphery 18 is formed with a corrugated plate 1 equivalent to the conventional slit or the matching post of the above embodiment.
This is the radio wave leakage characteristic in the case of a so-called chiyoke alone (a cross-sectional perspective view is shown in figure A'), which is a flat surface without 5w. Curve B indicates that a slit with a length of λo/12 (10 mm) is provided in the wall surface 15c (a cross-sectional perspective view is shown in Figure B'), and curve C indicates that the wall surface 15c is constructed of a corrugated plate 15w. (C' in the figure shows a cross-sectional perspective view). It is clear from FIG. 8 that the amount of radio wave leakage is smaller in the order of curve C, curve B, and curve A. That is, a high-frequency heating device equipped with a door 2 provided with a corrugated plate 15w has the smallest amount of radio wave leakage, and is suitable for cost reduction because it can remove ferrite, conductive rubber, and the like. Furthermore, as shown in FIG. 3, the radio wave attenuation cavity 19 has a fundamental wave channel groove and a second harmonic channel groove facing each other in opposite directions. As shown in Figure 3, the fundamental wave channel groove and the second harmonic channel channel are opposed to each other, and the length of the L-shaped radio wave propagation path in each channel is equal to the heating chamber opening periphery 18. The sum of the lengths in the parallel direction (z direction) and perpendicular direction (y direction) is λ/4 and λ/8, respectively.
I have to. Therefore, the dimensions of the radio wave attenuation cavity 19 in both the y direction and the z direction can be reduced,
The door can be made smaller and thinner, and it can be finished with a desirable appearance in terms of design that is in balance with the smaller and thinner operation panel. In addition, since the tip surface 15T of the corrugated plate 15w and the bent surface 16T of the end of the wall surface 16a of the fundamental wave cheese yoke groove 19a face each other on a plane, sparks and abnormal heating due to concentration of electromagnetic fields are prevented from occurring. be able to. As described above, according to the present invention, one radio wave attenuation cavity having one entrance in which the L-shaped fundamental wave channel groove and the L-shaped second harmonic channel groove are opposed to each other is installed in the door. a groove for the fundamental wave is arranged on the side closer to the heating chamber, and one wall surface of this groove is brought into planar contact with the periphery of the opening of the heating chamber,
The wall surface of the second harmonic chiyoke groove facing the heating chamber opening periphery is divided into a plurality of trapezoidal corrugated plates with bent tips, and the gap size between the corrugated plates is determined from the entrance size of the radio wave attenuation cavity. By increasing the size, it is possible to provide a high-frequency heating device equipped with a door that reduces radio wave leakage with a simple configuration, does not generate sparks or abnormal heating, and is suitable for downsizing, thinning, and cost reduction.

【図面の簡単な説明】[Brief explanation of the drawing]

第1図は本発明の高周波加熱装置の一実施例を
示す外観図、第2図は第1図に対応する本発明の
高周波加熱装置の一実施例を示す要部断面略図、
第3図は第2図における電波減衰空胴19付近の
拡大断面図、第4図、第5図および第6図は第2
高調波用チヨーク溝19bの壁面15c自体を整
合ポスト24,25を変形して波板15wとした
過程を説明するための説明図、第7図は電波減衰
空胴19の入口23付近での波板15wの作用を
説明するための図、第8図はチヨーク単独(曲線
A)、スリツト(曲線B)および本発明の波板1
5w(曲線C)を備えた各ドアにおける電波漏洩
量を比較した図である。 2……ドア、11……加熱室、15c……第2
高調波用チヨーク溝19bの壁面、15w……波
板、16a……基本波用チヨーク溝19aの壁
面、18……加熱室開口部周縁、19……電波減
衰空胴、19a……基本波用チヨーク溝、23…
…電波減衰空胴19の入口、A……入口寸法、B
……空隙寸法。
FIG. 1 is an external view showing an embodiment of the high-frequency heating device of the present invention, and FIG. 2 is a schematic sectional view of essential parts showing an embodiment of the high-frequency heating device of the present invention corresponding to FIG.
Figure 3 is an enlarged sectional view of the vicinity of the radio wave attenuation cavity 19 in Figure 2, and Figures 4, 5, and 6 are
An explanatory diagram for explaining the process of transforming the wall surface 15c of the harmonic chiyoke groove 19b itself into a corrugated plate 15w by deforming the alignment posts 24 and 25. FIG. A diagram for explaining the action of the plate 15w, and FIG.
5 is a diagram comparing the amount of radio wave leakage in each door equipped with 5w (curve C). 2...Door, 11...Heating chamber, 15c...Second
Wall surface of the harmonic chiyoke groove 19b, 15w... Corrugated plate, 16a... Wall surface of the fundamental wave chiyoke groove 19a, 18... Heating chamber opening periphery, 19... Radio wave attenuation cavity, 19a... For fundamental wave Chiyoke Groove, 23...
...Entrance of radio wave attenuation cavity 19, A...Entrance dimensions, B
...Gap size.

Claims (1)

【特許請求の範囲】[Claims] 1 加熱室開口部を開閉するドアの周縁に基本波
用チヨーク溝19aと第2高調波用チヨーク溝1
9bとを逆向きに対向させて一つの入口23を持
つ一つの電波減衰空洞19を構成し、基本波用チ
ヨーク溝19aを加熱室11に近い側に配置する
と共にこの溝19aの一壁面16aを加熱室開口
部周縁18と平面接触させ、第2高調波用チヨー
ク溝19bの加熱室開口部周縁18と対向する壁
面15cを複数の台形状の波板15wに分割し、
この波板15wには先端15w′を電波減衰空洞
19の内部に向かつて折り曲げた先端面15Tを
設け、この先端面15Tとほぼ平行に対向するよ
うに上記壁面16aの端部にも折り曲げ面16T
を設け、基本波用チヨーク溝19aおよび第2高
調波用チヨーク溝19bを共に加熱室開口部周縁
18に対して直角方向と平行方向から成るL字形
の電波伝搬経路を形成し、かつ隣り合う先端面1
5T間の空隙寸法Bを電波減衰空洞19の入口寸
法Aより大きくしたことを特徴とする高周波加熱
装置。
1 A chiyoke groove 19a for the fundamental wave and a chiyoke groove 1 for the second harmonic are provided on the periphery of the door that opens and closes the heating chamber opening.
9b are opposed in the opposite direction to form one radio wave attenuation cavity 19 having one inlet 23, and the fundamental wave chiyoke groove 19a is arranged on the side closer to the heating chamber 11, and one wall surface 16a of this groove 19a is arranged. A wall surface 15c facing the heating chamber opening periphery 18 of the second harmonic chiyoke groove 19b is divided into a plurality of trapezoidal corrugated plates 15w, which are brought into planar contact with the heating chamber opening periphery 18;
This corrugated plate 15w is provided with a tip surface 15T which is bent so that the tip 15w' faces inside the radio wave attenuation cavity 19, and a bent surface 16T is also provided at the end of the wall surface 16a so as to be opposed substantially parallel to this tip surface 15T.
The fundamental wave channel groove 19a and the second harmonic channel groove 19b together form an L-shaped radio wave propagation path consisting of a direction perpendicular and a direction parallel to the heating chamber opening periphery 18, and the adjacent tips Side 1
A high frequency heating device characterized in that a gap dimension B between 5T is larger than an entrance dimension A of a radio wave attenuation cavity 19.
JP15186781A 1981-09-25 1981-09-25 High frequency heater Granted JPS5853180A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
JP15186781A JPS5853180A (en) 1981-09-25 1981-09-25 High frequency heater
GB08224298A GB2106360B (en) 1981-09-25 1982-08-24 Microwave heating apparatus
US06/410,956 US4475023A (en) 1981-09-25 1982-08-24 Microwave heating apparatus with fundamental and second higher harmonic chokes
CA000410083A CA1184616A (en) 1981-09-25 1982-08-25 Microwave heating apparatus with fundamental and second higher harmonic chokes

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP15186781A JPS5853180A (en) 1981-09-25 1981-09-25 High frequency heater

Publications (2)

Publication Number Publication Date
JPS5853180A JPS5853180A (en) 1983-03-29
JPS6211475B2 true JPS6211475B2 (en) 1987-03-12

Family

ID=15527953

Family Applications (1)

Application Number Title Priority Date Filing Date
JP15186781A Granted JPS5853180A (en) 1981-09-25 1981-09-25 High frequency heater

Country Status (1)

Country Link
JP (1) JPS5853180A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0297234U (en) * 1989-01-18 1990-08-02

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5541679A (en) * 1978-09-19 1980-03-24 Sharp Kk Door for high frequency heating device

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5541679A (en) * 1978-09-19 1980-03-24 Sharp Kk Door for high frequency heating device

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0297234U (en) * 1989-01-18 1990-08-02

Also Published As

Publication number Publication date
JPS5853180A (en) 1983-03-29

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