JP2673347B2 - High frequency heating equipment - Google Patents

Description

【発明の詳細な説明】 産業上の利用分野 本発明は高周波加熱装置のドア構造の改良に関する。 従来の技術 高周波加熱装置のドア周縁に特性インピーダンスの異
なる溝を深さ方向に設け，この溝の深さ方向の特性イン
ピーダンスを不連続にすることにより実質的に深さが使
用波長の４分の１より小さくしても，溝の入口でのイン
ピーダンスが最大となり，チョーク溝を同様に漏洩電波
を少なくすることができるという提案が特開昭60−2519
0号公報にある。この従来例では，溝の深さ方向に幅の
異なる溝を設けたり，溝の周壁の形状を深さ方向に変形
するなどかなり形状が複雑である。また，特性インピー
ダンスの不連続部における反射防止を考慮する必要があ
る。 また，第７図で示すように，ドア５の外周に電波漏洩
防止用の空胴共振器12を屈曲形成してロ字状断面とし，
空胴共振器12の一周壁である張出面11の端部切口と空胴
共振器12の他の壁面（第１の壁面８）とを対向させた入
口25を有する構造が実開昭61−795号公報に示されてい
る。この従来例では空胴共振器12の周壁が複数の導体片
に分割されているとは記載されていない。したがって空
胴共振器12内には第８図に示す進行方向がyz面以外にも
生じる高次モードの電波が入ってくるため，空胴共振器
12が共振状態から外れ，電波漏洩防止効果が小さくな
る。仮りに第７図の空胴共振器12の立ち上がり面23と張
出面11を長手方向（ｘ方向）に使用波長の1/2より小さ
い幅の導体片に分割したと考える。この場合，空胴共振
器12を等価容量Ｃと等価インダクタンスＬとから成る並
列共振素子をドア５の長手方向（ｘ方向）に複数個並べ
たものとみなせる。各並列共振素子において，後述の
（２）式で示すように、空胴共振器12の入口25の第１の
壁面８側端部と空胴断面の面積中心Ｏの距離l_Mと、入口
寸法25との比l_M/Gが大きいほど等価容量Ｃが大きくな
る。第７図の空胴共振器12では で，後述する本発明の に比べて等価容量Ｃが小さくなる。その分だけ後述の
（３）式より等価インダクタンスＬを大きくして漏洩電
波の周波数に共振させるようにしなければならない。そ
のため，後述の（１）式から明らかなように，空胴共振
器12の断面ABを大きくする必要があるので，従来例の空
胴共振器12は大形となり，ドアの小形化，低コスト化に
は不向きである。 なお，第７図は実開昭61−795号公報の明細書の図面
の各部寸法を同一比率で示したものであり，また構成要
素の名称および番号は本発明と対応する部分は同じにし
てある。 発明が解決しようとする問題点 溝の深さ方向に，複雑な形状をした溝を設ける必要が
あり，また，特性インピーダンスの不連続部における反
射防止に手間が掛かったり，ドアの小形化に不向きな点
である。 問題点を解決するための手段 ドア周囲に口字状断面を持つ漏洩電波防止用の空胴共
振器を設け，この空胴共振器の４面のうち３面のドアの
周囲の長手方向に設けた多数のコ字状導体片で形成し，
残りの一面とコ字状導体片の端部切口とを互いに対向さ
せて上記空胴共振器に漏洩電波を導き入れる入口とし、
かつこの入口のコ字状導体片に対向する壁面側端部と空
胴断面の面積中心Ｏの距離l_Mと、入口寸法Ｇとの比l_M/G
を1.5以上とし，入口をふさぐ誘電体カバーを設け，そ
の最外周内面に設けた突起片をコ字状導体片の取付穴に
係止したものである。 作 用 上記のように構成することにより，コ字状導体片によ
り漏洩しようとする電波はTEM波として口字状断面の空
胴共振器内に導びき入れられる。この空胴共振器は，近
似的に１巻きの筒状コイルとして空胴断面積に比例した
等価インダクタンスＬと，空胴の入口付近の乱れ電界に
基づく等価容量Ｃとから成る並列共振素子を形成する。
空胴の入口を小さくするほどＣが大きくなり，その分だ
けＬを小さくできる。すなわち空胴断面積を小さくでき
る。口字状断面の各辺がそれぞれ使用波長の４分の１よ
りも小さい寸法で，電波シール効果が最大となる。 実施例 本発明の一実施例による高周波加熱装置の構成および
作用を図面とともに説明する。 第１図および第２図において,1は加熱室で,2は加熱室
１の開口部を取り囲むフランジで,3は外箱である。４は
加熱室１内を覗くためにドア５の中央部にできるだけ広
範囲に設けた***群である。６はこの***群４の周囲を
取り囲む段部でこの段部６は***群４の内面に固着した
透光性のドア内カバー15の端部が清掃の際などにはがれ
るのを防ぐと共に，ドア５閉成時にフランジ２と平面接
触する封口面７の平面度を良くするものである。８は封
口面７の端部よりフランジ２に対して略直角に折り曲げ
た第１の壁面である。９は第１の壁面８の端部よりフラ
ンジ２に対して略平行に延長した第２の壁面である。10
は第２の壁面９に溶接した多数のコ字状導体片である。
このコ字状導体片10は第２の壁面９に溶接される取り付
け面19と，第１の壁面８にほぼ平行に対向する立ち上が
り面23と，端部切口を第１の壁面８に対向させた張出面
11との３面から成る。ドア５の周囲の長手方向に対する
各コ字状導体片10の幅Ｄ（第３図のｘ方向）は使用波長
の２分の１よりも小さくしている。 又，第１の壁面８とコ字状導体片10とで囲まれた口字
状断面は狭小な入口25を有する空胴共振器12を形成す
る。この空胴共振器12の入口25をふさぐ不透明な誘電体
カバー13の最外周内面から突き出した突起片14はコ字状
導体片10の立ち上がり面23に設けた取り付け穴18に引っ
掛かるようになっている。ドア５の前面を覆う透光性の
ドア外カバー16を保持するための誘電体製のドア外枠24
から突き出した突起片17は第２の壁面９の最外周縁端部
20に引っ掛かるようになっている。 次に上記のように構成した実施例の作用効果を説明す
る。加熱室１開口部を取り囲むフランジ２と封口面７と
の平面接触部に向かう入射電波に対して，第４図のよう
な簡易等価回路によって定性的に電波シール効果を説明
する。21はフランジ２と封口面７との平面接触部に対応
する容量で，一種のバイパスコンデンサとして作用す
る。平面接触部は平行板線路と考えられ，この線路の容
量は平行板のキヤップに比例するので容量21は上記平面
接触部のキヤップが小さいほど大きくなり，電波シール
効果が増す。コ字状導体片10の幅Ｄ（第３図のｘ方向）
を使用波長の２分の１より小さくしているので，第１の
壁面８と各コ字状導体片10とで形成された口字状断面を
持つ空胴共振器12の内部に入り込んだ電波の進行方向は
第３図yz面内に限定される。張出面11が無ければ第６図
のように電界が分布し，平行板線路の長さｌが自由空間
波長λの約４分の１で並列共振を起こし，インピーダン
スが最大となり，電波漏洩を防止することができるが,2
450MHzの高周波加熱装置ではｌは30.6mmで，これをドア
に実装しようとすると厚くなり，意匠的にもコスト的に
も不利である。 本実施例のように，張出面11を設けて，口字状断面を
持ち狭小な入口25を有する空胴共振器12を形成した場合
は，第５図のような電界分布となる。この場合，張出面
11の端部切口付近と第１の壁面８との間に電気力線の大
部分が集まっている。空胴共振器12は第４図において等
価インダクタンスＬと等価容量Ｃとから成る並列共振素
子として表わされている。等価インダクタンスＬは，近
似的に空胴共振器12と同じ断面の１巻きの筒状コイルと
して働き，そのコイルの定数としての等価的なインダク
タンスを意味し，筒軸方向（ｘ方向）の単位長あたりの
値は（１）式のようになる。また，等価容量Ｃは空胴共
振器12の入口25付近の乱れ電界に基づくもので，近似的
に（２）式で与えられる。 Ｌ＝μ_oAB ……（１） ここで， AB:空胴共振器12の口字状断面の面積 μ_o:空胴共振器12内の媒質の透磁率 e:2.72 l_M:入口25の第１の壁面８側端部と空胴断面の面積中心
Ｏの距離 ε_o:空胴共振器12内の媒質の誘電率 K:入口25付近の形状に関係する補正項 G:入口25の間隙（入口寸法） 空胴共振器12の共振周波数f_oは（３）式で表わせる。 （２）式より入口25の間隙Ｇを小さくするほど，ある
いはl_M/Gを大きくするほど等価容量Ｃが大きくなること
がわかる。共振周波数f_oを一定とすると，等価容量Ｃが
大きくなるほど等価インダクタンスＬが小さくてよいこ
とが（３）式からわかる。等価インダクタンスＬを小さ
くするには（１）式より空胴共振器12の口字状断面の面
積ABを小さくすればよい。すなわち，空胴共振器12を小
形にするためには，入口25の間隙Ｇを狭くして等価容量
Ｃを大きくし，その分だけ空胴断面積ABを小さくして等
価インダクタンスＬを小さくし，一定の共振周波数f
_o（高周波加熱装置の加熱周波数）で並列共振を起こさ
せて，入口25におけるインピーダンスを最大にし，電波
漏洩を防止すればよい。 加熱周波数が2,450MHz,高周波出力が500Wの高周波加
熱装置において，フランジ２と封口面７との間の間隙を
2mm,張出面11と封口面７との段差を3mm,コ字状導体片の
幅口を15mmとし，水275mlを加熱してドア５の周囲から5
cmの距離で電波漏洩量を測定してみた。その結果,G＝5m
mのとき,AB＝15.4×15.9mm, で，電波漏洩量が0.1m w/cm²以下となり,G＝8mmと大き
くすると，上記と同程度に少ない電波漏洩量に抑えるた
めには というように口字状断面の面積も大きくなる。このよう
な実験により，入口25の間隙Ｇを４〜8mm位と狭小にし
てl_M/Gを1.5以上にすることにより，口字状断面の空胴
共振器12の寸法Ａおよび寸法Ｂをそれぞれ使用波長λの
４分の１である30.6mmよりもかなり小さくできることが
明らかとなっている。 また，誘電体カバー13は突起片14をコ字状導体片10の
取り付け穴18に引っ掛けることによりドア５に簡単に固
着できるので取り付け作業性が良い。 発明の効果 以上のように本発明によると，多数のコ字状導体片と
第１の壁面とで囲まれた口字状断面の空胴共振器の入口
をコ字状導体片の張出面の端部切口と第１の壁面を対向
させた構成で狭小なものとし，かつ のように寸法を選んだので，空胴共振器の断面寸法Ａお
よびＢを使用波長λの４分の１よりも小さくでき，空胴
共振器の形状が簡単となり，ドアの小形化，薄形化が図
れ，かつ入口をふさぐ誘電体カバーの取り付け作業性も
良く，又コ字状導体片の一端面は第２の壁面に接触させ
る構成であり，取付が簡単となる効果がある。Description: TECHNICAL FIELD The present invention relates to an improvement in a door structure of a high-frequency heating device. 2. Description of the Related Art Grooves having different characteristic impedances are provided in the depth direction on the periphery of a door of a high-frequency heating device, and by making the characteristic impedances in the depth direction of the grooves discontinuous, the depth is practically a quarter of the used wavelength. A proposal that the impedance at the entrance of the groove becomes maximum even if it is made smaller than 1 and the leaked radio waves can be similarly reduced in the choke groove is disclosed in JP-A-60-2519.
No. 0 publication. In this conventional example, a groove having a different width is provided in the depth direction of the groove, or the shape of the peripheral wall of the groove is deformed in the depth direction, so that the shape is considerably complicated. In addition, it is necessary to consider prevention of reflection at a discontinuous portion of the characteristic impedance. In addition, as shown in FIG. 7, a cavity resonator 12 for preventing electric wave leakage is formed in a bent shape on the outer periphery of the door 5 to have a square cross section,
A structure having an entrance 25 in which an end cut of the overhanging surface 11 which is one circumferential wall of the cavity resonator 12 and the other wall surface (first wall surface 8) of the cavity resonator 12 are opposed to each other is actually developed. No. 795 is shown. In this conventional example, it is not described that the peripheral wall of the cavity resonator 12 is divided into a plurality of conductor pieces. Accordingly, radio waves of higher-order modes in which the traveling direction shown in FIG.
12 deviates from the resonance state, and the effect of preventing radio wave leakage decreases. It is assumed that the rising surface 23 and the projecting surface 11 of the cavity 12 shown in FIG. 7 are divided into conductor pieces having a width smaller than 1/2 of the wavelength used in the longitudinal direction (x direction). In this case, the cavity resonator 12 can be regarded as a plurality of parallel resonant elements each having an equivalent capacitance C and an equivalent inductance L arranged in the longitudinal direction (x direction) of the door 5. In each of the parallel resonant elements, as shown by the following expression (2), the distance l _M between the end of the cavity 25 on the first wall 8 side of the entrance 25 and the area center O of the cavity cross section, and the entrance dimension As the ratio l _M / G to 25 increases, the equivalent capacitance C increases. In the cavity resonator 12 of FIG. Therefore, the , The equivalent capacitance C becomes smaller. It is necessary to increase the equivalent inductance L from equation (3) described later to resonate with the frequency of the leaked radio wave. For this reason, as is apparent from equation (1) described later, it is necessary to increase the cross section AB of the cavity resonator 12, so that the cavity resonator 12 of the conventional example becomes large, so that the door can be downsized and the cost can be reduced. It is not suitable for transformation. FIG. 7 shows the dimensions of each part in the drawing of the specification of Japanese Utility Model Laid-Open No. 61-795 in the same ratio, and the names and numbers of the components are the same in the parts corresponding to the present invention. is there. Problems to be Solved by the Invention It is necessary to provide a groove having a complicated shape in the depth direction of the groove, and it takes time to prevent reflection at discontinuous portions of characteristic impedance, and is not suitable for downsizing doors. It is a point. Means for Solving the Problems A cavity for preventing leaked radio waves having a square cross section is provided around the door, and three of the four faces of the cavity resonator are provided in the longitudinal direction around the door. Formed from a number of U-shaped conductor pieces
The remaining one surface and the end cut of the U-shaped conductor piece are opposed to each other to serve as an inlet for introducing leaked radio waves into the cavity resonator,
Also, the ratio of the distance l _M between the wall-side end facing the U-shaped conductor piece of the inlet and the area center O of the cavity cross section to the inlet dimension G l _M / G
Is 1.5 or more, a dielectric cover is provided to close the inlet, and the protruding piece provided on the innermost peripheral surface is locked in the mounting hole of the U-shaped conductor piece. Operation With the configuration described above, radio waves to be leaked by the U-shaped conductor pieces are guided into the cavity resonator having a square cross section as TEM waves. This cavity resonator forms a parallel resonance element, which is approximately a one-turn cylindrical coil and is composed of an equivalent inductance L proportional to the cavity cross-sectional area and an equivalent capacitance C based on a turbulent electric field near the entrance of the cavity. To do.
As the entrance of the cavity becomes smaller, C becomes larger, and L can be made smaller accordingly. That is, the cavity sectional area can be reduced. The radio wave sealing effect is maximized when each side of the square cross section is smaller than a quarter of the wavelength used. Embodiment The configuration and operation of a high-frequency heating device according to an embodiment of the present invention will be described with reference to the drawings. In FIGS. 1 and 2, 1 is a heating chamber, 2 is a flange surrounding the opening of the heating chamber 1, and 3 is an outer box. Reference numeral 4 denotes a group of small holes provided as widely as possible in the center of the door 5 to look inside the heating chamber 1. Reference numeral 6 denotes a step portion that surrounds the group of small holes 4. The step portion 6 prevents the end portion of the translucent door inner cover 15 fixed to the inner surface of the small hole group 4 from being peeled off at the time of cleaning and also at the door. 5 The flatness of the sealing surface 7 that comes into planar contact with the flange 2 when closed is improved. Reference numeral 8 denotes a first wall surface which is bent substantially perpendicularly to the flange 2 from the end of the sealing surface 7. Reference numeral 9 denotes a second wall extending from the end of the first wall 8 substantially parallel to the flange 2. Ten
Is a large number of U-shaped conductor pieces welded to the second wall surface 9.
This U-shaped conductor piece 10 has a mounting surface 19 to be welded to the second wall surface 9, a rising surface 23 facing substantially parallel to the first wall surface 8, and an end cut facing the first wall surface 8. Overhang
It consists of 3 sides with 11. The width D (x direction in FIG. 3) of each U-shaped conductor piece 10 with respect to the longitudinal direction around the door 5 is smaller than one-half of the wavelength used. The square cross section surrounded by the first wall surface 8 and the U-shaped conductor piece 10 forms the cavity resonator 12 having the narrow inlet 25. The protruding piece 14 protruding from the outermost peripheral inner surface of the opaque dielectric cover 13 that closes the entrance 25 of the cavity resonator 12 is adapted to be caught in the mounting hole 18 provided in the rising surface 23 of the U-shaped conductor piece 10. There is. A dielectric door outer frame 24 for holding a translucent door outer cover 16 covering the front surface of the door 5.
The protruding piece 17 protruding from the outermost peripheral edge of the second wall surface 9
It is designed to be hooked on 20. Next, the operation and effect of the embodiment configured as described above will be described. The radio wave sealing effect will be qualitatively described by a simple equivalent circuit as shown in FIG. 4 with respect to the radio wave incident toward the plane contact portion between the flange 2 surrounding the opening of the heating chamber 1 and the sealing surface 7. Reference numeral 21 denotes a capacitance corresponding to a plane contact portion between the flange 2 and the sealing surface 7, and acts as a kind of bypass capacitor. The plane contact part is considered to be a parallel plate line, and the capacitance of this line is proportional to the cap of the parallel plate. Therefore, the capacitance 21 increases as the cap of the plane contact part decreases, and the radio wave sealing effect increases. Width D of the U-shaped conductor piece 10 (x direction in FIG. 3)
Is smaller than one half of the used wavelength, the radio wave entering the cavity resonator 12 having a square cross section formed by the first wall surface 8 and each U-shaped conductor piece 10. The traveling direction of is limited to the yz plane in FIG. If there is no overhanging surface 11, the electric field will be distributed as shown in Fig. 6, and parallel resonance will occur when the length 1 of the parallel plate line is about 1/4 of the free space wavelength λ, and the impedance will be maximum and the radio wave leakage will be prevented. But you can, 2
With a high-frequency heating device of 450 MHz, l is 30.6 mm, and when it is mounted on a door, it becomes thick, which is disadvantageous in terms of design and cost. When the overhanging surface 11 is provided and the cavity resonator 12 having the narrow cross-section and the narrow inlet 25 is formed as in this embodiment, the electric field distribution is as shown in FIG. In this case, the overhang surface
Most of the lines of electric force are gathered between the vicinity of the 11 end cut and the first wall surface 8. The cavity resonator 12 is shown in FIG. 4 as a parallel resonance element having an equivalent inductance L and an equivalent capacitance C. The equivalent inductance L functions as a one-turn cylindrical coil having a cross section approximately the same as that of the cavity resonator 12, and means an equivalent inductance as a constant of the coil, and is a unit length in the cylinder axis direction (x direction). The value per is as shown in equation (1). The equivalent capacitance C is based on a turbulent electric field near the entrance 25 of the cavity resonator 12, and is approximately given by the equation (2). L = μ _o AB (1) Where AB: area of the cavity-shaped cross section of the cavity resonator 12 μ _o : permeability of the medium in the cavity resonator 12 e: 2.72 l _M : end of the inlet 25 on the first wall surface 8 side and the cavity Distance of the center O of the cross section of the body ε _o : Permittivity of the medium in the cavity resonator K: Correction term related to the shape near the inlet 25 G: Gap of the inlet 25 (inlet dimension) of the cavity resonator 12 the resonance frequency f _o is expressed by equation (3). From equation (2), it can be seen that the smaller the gap G at the inlet 25 or the larger l _M / G, the larger the equivalent capacity C becomes. When a constant resonant frequency f _o, the more the equivalent inductance L equivalent capacitance C increases that may be less apparent from equation (3). In order to reduce the equivalent inductance L, the area AB of the square cross section of the cavity resonator 12 may be reduced according to the equation (1). That is, in order to make the cavity resonator 12 small, the gap G of the inlet 25 is narrowed to increase the equivalent capacitance C, and the cavity cross-sectional area AB is reduced by that amount to reduce the equivalent inductance L. Constant resonance frequency f
_It suffices to cause parallel resonance at (the heating frequency of the high frequency heating device) to maximize the impedance at the inlet 25 and prevent radio wave leakage. In a high-frequency heating device with a heating frequency of 2,450 MHz and a high-frequency output of 500 W, the gap between the flange 2 and the sealing surface 7
2 mm, the step between the overhanging surface 11 and the sealing surface 7 is 3 mm, the width opening of the U-shaped conductor piece is 15 mm, and 275 ml of water is heated from the periphery of the door 5 to 5 mm.
I measured the amount of radio wave leakage at a distance of cm. As a result, G = 5m
When m, AB = 15.4 × 15.9mm, Therefore, if the amount of radio wave leakage is less than 0.1 mw / cm ² and G = 8 mm, it is necessary to reduce the amount of radio wave leakage to the same level as above. Thus, the area of the square-shaped cross section also increases. According to such an experiment, the gap G of the inlet 25 is narrowed to about 4 to 8 mm and l _M / G is set to 1.5 or more, so that the dimension A and the dimension B of the cavity resonator 12 having the square cross section are respectively set. It has become clear that it can be made considerably smaller than 30.6 mm, which is a quarter of the used wavelength λ. Further, the dielectric cover 13 can be easily fixed to the door 5 by hooking the projection piece 14 in the mounting hole 18 of the U-shaped conductor piece 10, so that the mounting workability is good. EFFECTS OF THE INVENTION As described above, according to the present invention, the inlet of a cavity resonator having a U-shaped cross section surrounded by a large number of U-shaped conductor pieces and the first wall is connected to the protruding surface of the U-shaped conductor piece. The end face and the first wall face are made to face each other to make it narrow, and Since the dimensions are selected as shown below, the cross-sectional dimensions A and B of the cavity resonator can be made smaller than a quarter of the operating wavelength λ, the cavity resonator can be simplified in shape, and the door can be made smaller and thinner. In addition, the workability of attaching the dielectric cover that closes the inlet is good, and one end surface of the U-shaped conductor piece is in contact with the second wall surface, which has the effect of simplifying the attachment.

【図面の簡単な説明】 第１図は本発明の一実施例による高周波加熱装置のドア
５の金属部だけを示す要部斜視図，第２図は同ドア周囲
の電波シール部を示す要部断面図，第３図は同電界方向
を示す図，第４図はドア５の電波シール部の簡易等価回
路図，第５図は同電波シール部の電界分布図，第６図は
同終端を短絡した平行板線路の電界分布図，第７図は従
来の電波シール構造を示す構成説明図，第８図は同電界
方向を示す図である。 １……加熱室,2……フランジ,4……***群， ５……ドア,6……段部,7……封口面， ８……第１の壁面,9……第２の壁面， 10……コ字状導体片,11……張出面， 12……空胴共振器,13……誘電体カバー， 14……突起片,18……取り付け面,19……取り付け面， 23……立ち上がり面,25……入口， l_M……空胴共振器12の入口25の第１の壁面８側端部と空
胴断面の面積中心Ｏとの距離、 Ｇ……入口寸法。BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a main part showing only a metal part of a door 5 of a high-frequency heating device according to an embodiment of the present invention, and FIG. 2 is a main part showing a radio wave seal part around the door. FIG. 3 is a diagram showing the same electric field direction, FIG. 4 is a simplified equivalent circuit diagram of a radio wave seal portion of the door 5, FIG. 5 is an electric field distribution diagram of the radio wave seal portion, and FIG. FIG. 7 is an explanatory diagram of the electric field distribution of a short-circuited parallel plate line, FIG. 7 is an explanatory diagram showing the configuration of a conventional radio wave seal structure, and FIG. 8 is a diagram showing the same electric field direction. 1 ... Heating chamber, 2 ... Flange, 4 ... Small hole group, 5 ... Door, 6 ... Step, 7 ... Sealing surface, 8 ... First wall surface, 9 ... Second wall surface, 10 …… U-shaped conductor piece, 11 …… Overhanging surface, 12 …… Cavity resonator, 13 …… Dielectric cover, 14 …… Projecting piece, 18 …… Mounting surface, 19 …… Mounting surface, 23… … Rise surface, 25 …… Inlet, l _M …… Distance between the end of the entrance 25 of the cavity resonator 12 on the first wall surface 8 side and the center O of the cavity cross section, G …… Inlet dimension.

───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 昭61−124091（ＪＰ，Ａ)   ────────────────────────────────────────────────── ─── Continuation of front page    (56) References JP-A-61-124091 (JP, A)

Claims (1)

(57)【特許請求の範囲】 １．加熱室（１）開口部を開閉するドア（５）の周縁に
位置し、ドア（５）閉成時には加熱室（１）開口部のフ
ランジ（２）に平面接触する封口面（７）と、この封口
面（７）の端部よりフランジ（２）に対して略直角の第
１の壁面（８）と、この第１の壁面（８）の端部よりフ
ランジ（２）に対して略平行に延長した第２の壁面
（９）と、この第２の壁面（９）と略直角の立ち上がり
面（23）と、この立ち上がり面（23）と略直角の張出面
（11）とを備えた高周波加熱装置において、第２の壁面
（９）に端面が接した多数のコ字状導体片（10）を設
け、第１の壁面（８）とコ字状導体片（10）とによりロ
字状断面を形成すると共に入口（25）を有する空胴共振
器（12）を形成し、かつ入口（25）の第１の壁面（８）
側端部と空胴断面の面積中心（Ｏ）の距離（l_M）と、入
口寸法（Ｇ）との比l_M/Gを1.5以上とし、かつ上記空胴
共振器（12）の入口（25）をふさぐ誘電体カバー（13）
を設け、その最外周内面に設けた突起片（14）をコ字状
導体片（10）の取付け穴（18）に外面方向から引っ掛け
て誘電体カバー（13）をドア（５）に固着し、コ字状導
体片（10）は第２の壁面（９）に接する取り付け面（1
9）と、第１の壁面（８）にほぼ平行に対向する立ち上
がり面（23）と、端部切口を第１の壁面（８）に対向さ
せた張出面（11）との３面から成り、空胴共振器（12）
の入口（25）は張出面（11）の端部切口と第１の壁面
（８）を対向させて形成したことを特徴とする高周波加
熱装置。(57) [Claims] A sealing surface (7) located on the periphery of the door (5) that opens and closes the opening of the heating chamber (1) and comes into flat contact with the flange (2) of the opening of the heating chamber (1) when the door (5) is closed; A first wall surface (8) substantially perpendicular to the flange (2) from the end of the sealing surface (7), and substantially parallel to the flange (2) from the end of the first wall surface (8). A second wall surface (9) extended to the above, a rising surface (23) substantially perpendicular to the second wall surface (9), and a projecting surface (11) substantially perpendicular to the rising surface (23). In the high frequency heating device, a large number of U-shaped conductor pieces (10) whose end faces are in contact with the second wall surface (9) are provided, and the first wall surface (8) and the U-shaped conductor piece (10) form a square shape. Forming a cavity resonator (12) having a cross section and having an inlet (25), and forming a first wall surface (8) of the inlet (25)
The ratio l _M / G of the distance (l _M ) between the side end and the area center (O) of the cavity cross section to the inlet dimension (G) is set to 1.5 or more, and the inlet of the cavity resonator (12) ( 25) Dielectric cover (13)
And the projection piece (14) provided on the innermost peripheral surface thereof is hooked from the outer surface direction to the mounting hole (18) of the U-shaped conductor piece (10) to fix the dielectric cover (13) to the door (5). , The U-shaped conductor piece (10) attaches to the second wall surface (9) (1
9), a rising surface (23) facing substantially parallel to the first wall surface (8), and an overhanging surface (11) with the end cut facing the first wall surface (8). , Cavity resonators (12)
The inlet (25) of the above is formed by making the end cut end of the overhanging surface (11) and the first wall surface (8) face each other.