EP0543687B1 - Magnetron für einen Mikrowellenherd - Google Patents

Magnetron für einen Mikrowellenherd Download PDF

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Publication number
EP0543687B1
EP0543687B1 EP19920402719 EP92402719A EP0543687B1 EP 0543687 B1 EP0543687 B1 EP 0543687B1 EP 19920402719 EP19920402719 EP 19920402719 EP 92402719 A EP92402719 A EP 92402719A EP 0543687 B1 EP0543687 B1 EP 0543687B1
Authority
EP
European Patent Office
Prior art keywords
magnetron
spacer
lead
microwave oven
seal
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 - Lifetime
Application number
EP19920402719
Other languages
English (en)
French (fr)
Other versions
EP0543687A1 (de
Inventor
Gi Il Do
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.)
LG Electronics Inc
Original Assignee
LG Electronics Inc
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 LG Electronics Inc filed Critical LG Electronics Inc
Publication of EP0543687A1 publication Critical patent/EP0543687A1/de
Application granted granted Critical
Publication of EP0543687B1 publication Critical patent/EP0543687B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J23/00—Details of transit-time tubes of the types covered by group H01J25/00
    • H01J23/14—Leading-in arrangements; Seals therefor
    • H01J23/15—Means for preventing wave energy leakage structurally associated with tube leading-in arrangements, e.g. filters, chokes, attenuating devices
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J23/00—Details of transit-time tubes of the types covered by group H01J25/00
    • H01J23/14—Leading-in arrangements; Seals therefor

Definitions

  • the present invention relates to a magnetron for a microwave oven, and more particularly to a magnetron for a microwave oven wherein a spacer having a disc shape is fitted between a lower pole piece and a filament seal V(F-seal) supporting the lower pole piece and provided at its upper surface with a metal coating or plate, thereby removing effectively leaked microwaves and avoiding a lateral vibration of a lead assembly.
  • a magnetron for a microwave oven comprises a diode for emitting thermions.
  • FIG. 1 there is illustrated an example of a conventional magnetron for a microwave oven.
  • the magnetron comprises a magnetron body 1, and a filament 2 disposed in the magnetron body 1 and adapted to emit thermions.
  • the magnetron body 1 is disposed in a casing constituted by an upper member 5 of a plate shape and a lower member 6 of a cylindrical shape.
  • the magnetron body 1 also has upper and lower portions protruded beyond upper and lower members 5 and 6, respectively.
  • a seal V(A-seal) member 3 and a filament seal (F-seal) member 4 are provided at the upper and lower portions of the magnetron body 1.
  • the seal members 3 and 4 also function as a magnetic path.
  • a vane 7 is placed to receive microwave energy generated when the thermions emitted from the filament 2 are acceleratively rotated in an interaction spacer 9.
  • a strap 16 is also provided for adjusting frequencies of the thermions rotating acceleratively in the interaction space 9.
  • the magnetron also comprises an antenna feeder 8 adapted as a microwave transmission path for guiding microwave energy received by the vane 7 into a cooking chamber.
  • upper and lower permanent magnets 10 and 10' are attached to upper and lower members 5 and 6, respectively, to generate a magnetic field.
  • the magnetic field is applied to the interaction space 9, by means of pole pieces 11 and 11'.
  • a plurality of cooling fins 12 are disposed which function to release outwardly heat generated at the side of vane 7 and thus cool the interior of magnetron body 1.
  • a center lead 17 and a side lead 18 are connected at their one ends to both ends of the filament 2, respectively, so as to apply electric power to the filament 2.
  • a through type condenser 14 is connected, which functions as a terminal making it possible to apply easily electric power from the outside to the filament 2.
  • a choke coil 15 is also provided to remove conductive noise generated by lead current.
  • the condenser 14 cooperates with the choke coil 15 to enhance a shield effect on conductive noise.
  • Beneath the housing a filter box 13 is disposed to surround the lower portion of the magnetron body 1.
  • the filter box 13 functions to remove radiation noise emitting through both the center lead 17 and the side lead 18.
  • a spacer 19 is also provided to support both the center lead 17 and the side lead 18.
  • a cathode terminal 20 is mounted to the lower end of the magnetron body 1.
  • An F-ceramic member 21 is also provided between the F-seal member 4 and the cathode terminal 20.
  • the filament 2 emits thermions which are, in turn, radiated into the interaction space 9.
  • the thermions conduct a cycloidal movement, that is, an accelerated rotation, by axial magnetic fluxes generated from the pole pieces 11 and 11' and an electric field generated between the filament 2 and the vane 7.
  • microwave energy transmitted to the vane 7 is fed into the cooking chamber, via the antenna feeder 8 and a waveguide (not shown) of the oven, thereby heating the food placed in the cooking chamber.
  • the magnetron generates microwaves which includes basic frequency of 2.45 GHz and harmful higher harmonics having a frequency corresponding to a multiple of the basic frequency.
  • microwaves are desired to go to the output part of magnetron, namely, the antenna feeder 8, in actual, a part of the microwaves flows usually toward the inlet part of magnetron, via the center lead 17, the side lead 18 and the cathode terminal 20.
  • the microwave shielding device comprises a microwave shielding choke 22 having a certain shape and fixed to the inner wall of F-seal 4.
  • the leakage of microwave is effectively prevented by the microwave shielding choke 22.
  • the device requires use of a separate jig for fixing the choke 22, which causes a deterioration in workability in the manufacture of magnetrons and an expensive manufacture cost.
  • U.S. Patent No. 4,684,845 discloses a device for preventing both the center lead and the side lead from vibrating due to such a mechanical vibration and for maintaining a proper space between the center lead and the side lead.
  • a spacer is mounted to upper portions of the leads.
  • the spacer serves effectively to hold the leads at their spaced state. If both the leads vibrate laterally at the same time, however, the spacer then vibrates laterally. As a result, a vibration restraining effect is reduced. Moreover, it is required to form a groove for positioning the spacer at a curved portion of the center lead. It is also needed to provide sleeves. These requirements make a deterioration in workability in the manufacture of magnetrons and an increase in manufacturing cost.
  • EP-A-339 374 Another magnetron having a choke for preventing leakage of harmonics is disclosed in EP-A-339 374.
  • a magnetron according to EP-A-339 374 has a choke formed by a metal piece with slots or by conductive films on the magnetron side of a reversed ceramic stem insulator.
  • An object of the invention is to eliminate the above-mentioned problems encountered in the prior art and to provide a magnetron for a microwave oven capable of effectively avoiding the leakage of microwaves.
  • Another object of the invention is to provide a magnetron for a microwave oven capable of effectively restraining vibrations of its lead assembly, thereby avoiding the breaking down of its filament and a disturbance in its interaction space.
  • Another object of the invention is to provide a magnetron for a microwave oven capable of effectively avoiding the leakage of microwaves and restraining vibrations of its lead assembly, with a simple construction, thereby saving the manufacture cost and improving workability in the manufacture thereof.
  • the insulating portions in the metal plate or coating for insulating the center lead and the side lead have a radius which is larger than that of each corresponding lead, by at least 0.1 mm.
  • the spacer may also have an additional metal coating at the lower surface thereof.
  • the spacer is disc shaped and may have a tapered peripheral portion, in which cave the filament seal (F-seal) has a smoothly curved portion for supporting the tapered portion of the spacer.
  • the spacer has a vertical peripheral portion which is perpendicular to both the upper and lower surfaces of the spacer and correspondingly, the filament seal (F-seal) has a step for supporting the spacer thereon.
  • the attenuation cavity which is defined by the lower pole piece and the metal coating or plate of spacer serves to resonate and thus attenuate undesirable higher harmonics therein. As a result, any leakage of microwaves is avoided. Furthermore, since the spacer is fitted at its peripheral portion between the filament seal (or F-seal) and the lower pole piece, simultaneous lateral vibrations of both the leads and thus the disturbance in the interaction space can be avoided.
  • FIG. 3 is a sectional view of a part of a magnetron for a microwave oven according to the present invention.
  • FIGS. 4A and 4B are a plan view and a sectional view of a spacer used in the magnetron according to an embodiment of the present invention, respectively.
  • the magnetron of the present invention has constructions partially similar to those shown in FIG. 2. Accordingly, the same or similar elements are denoted by the same reference numerals.
  • the magnetron of the present invention eliminates use of the spacer 19, the slider 23 and the microwave shielding choke 22.
  • the magnetron comprises a disc-shaped spacer 30 fitted in a coupling area between the F-seal 4 and the lower pole piece 11' in accordance with the present invention, as shown in FIG. 2.
  • a metal coating 33 is provided in a proper thickness and thus defines an attenuation cavity 36, together with the lower pole piece 11'. The metal coating 33 is in contact with the lower pole piece 11' and thus electrically connected to the ground, via the magnetron body.
  • metal plate members may be used which serve the same function as that of the metal coating.
  • the spacer 30 has at its proper portions a pair of lead holes 31 and 32 through which the center lead 17 and the side lead 18 extend, respectively.
  • insulating portions 34 and 35 for insulating the leads 17 and 18 from each other are provided around the lead holes 31 and 32, respectively.
  • Each insulating portion 34 (or 35) may be provided by removing an area corresponding to the insulation portion from the metal coating 33 and has a radius larger than that of each lead hole 31 (or 32), by a predetermined dimension L.
  • the predetermined dimension L is not less than 0.1 mm.
  • the spacer 30 also has a taper shape at its peripheral portion so that it can be held in position by fitting the tapered peripheral portion in the coupling area between a curved portion of the F-seal 4 and the lower pole piece 11'.
  • the filament 2 As electric power is applied to the filament 2 via the center lead 17 and the side lead 18, the filament 2 emits thermions.
  • the emitted thermions are radiated into the interaction space 9 and conduct an accelerated rotation therein, by axial magnetic fluxes generated from the pole pieces 11 and 11' and an electric field generated between the filament 2 and the vane 7.
  • microwave energy transmitted to the vane 7 is fed into the cooking chamber, via the antenna feeder 8 and a waveguide (not shown) of the oven, thereby heating the food placed in the cooking chamber.
  • microwaves may be leaked into the interior of the filter box 13 (shown in FIG. 1) via the center lead 17 and the side lead 18, due to an oscillation of magnetron. These leaked undesirable microwaves are resonated and thus attenuated by the attenuation cavity 36 which is defined by the lower pole piece 11' and the metal coating 33 formed on the spacer 30.
  • the harmful higher harmonics radiated between the lower pole piece 11' and the filament seal (F-seal) 4 and leaked along the ceramic member 21 can be shielded, thereby avoiding the microwaves from being leaked outwardly of the filter box 13.
  • the spacer 30 also functions to transfer heat transmitted to the choke coil 15 (shown in FIG. 1) via the center lead 17 and the side lead 18, to the filament seal (F-seal) 4. Accordingly, it is possible to prevent a phenomenon that a coating formed on the chock coil 15 is oxidized.
  • both the center lead 17 and the side lead 18 maintain their space in that they are held in position by means of the lead holes 31 and 32 formed in the spacer 30.
  • FIGS. 5A and 5B illustrate a plan view and a sectional view of a magnetron according to another embodiment of the present invention, respectively.
  • the magnetron of this embodiment has the same construction as that of the above-mentioned embodiment, except that an additional metal coating 33' is formed at the lower surface of the spacer 30 which has at its upper surface the metal coating 33.
  • the magnetron of this embodiment can enhance more effectively the microwave shielding effect, in that the spacer 30 has metal coatings 33 and 33' at both surfaces thereof.
  • the spacer 30 has a vertical peripheral portion which is perpendicular to both upper and lower surfaces of the spacer 30.
  • the F-seal 4 has at its curved portion a step adapted to support the spacer 30 thereon.
  • the spacer 30 may have the metal coating only at its upper surface or metal coatings at both upper and lower surfaces.
  • the present invention provides a spacer which has a metal coating (or plate) at its upper end or metal coatings (or plates) at both upper and lower surfaces and thereby achieves an improvement in anti-leakage of microwaves. Since the spacer is also firmly fitted between the lower pole piece and the curved portion of F-seal, vibrations, in particular, lateral vibrations of the leads can be effectively avoided.
  • the fitting of the spacer having a disc shape can also be easily accomplished by a simple work, without using separate jig or sleeves. Accordingly, there is an improvement in workability in the manufacture.

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  • Electric Ovens (AREA)

Claims (6)

  1. Magnetron für einen Mikrowellenherd, enthaltend
    ein Magnetrongehäuse (1); eine Zentralleitung (17) und eine Nebenleitung (18), die sich jeweils durch das Magnetrongehäuse (1) erstrecken; obere und untere Polteile (11, 11'), die jeweils mit oberen und unteren Abschnitten des Magnetrongehäuses (1) verbunden sind und zwischen denen sich ein Interaktionsraum (9) befindet; sowie eine Faserdichtung (4), die den unteren Polteil (11') stützt,
    gekennzeichnet durch folgende weitere Bauteile:
    - einen Abstandshalter (30), der in einem von der Faserdichtung (4) und dem unteren Polteil (11') begrenzten Befestigungsabschnitt angebracht und mit einem Paar von Leitungsöffnungen versehen ist, durch die sich jeweils die Zentralleitung (17) und die Nebenleitung (18) ertrecken; und
    - eine Metallplatte (33), die an der oberen Außenfläche des Abstandshalters (30) angebracht ist und zusammen mit dem unteren Polteil (11') einen Dämpfungshohlraum begrenzt, wobei die Metallplatte (33) ein Paar von Isolierabschnitten (34, 35) zum gegenseitigen Isolieren der Zentralleitung (17) von der Nebenleitung (18) aufweist.
  2. Magnetron für einen Mikrowellenherd gemäß Anspruch 1, wobei jeder Isolierabschnitt (34, 35) einen Radius aufweist, der um wenigstens 0,1 mm größer ist als der Radius der jeweiligen entsprechenden Leitung.
  3. Magnetron für einen Mikrowellenherd gemäß einem der Ansprüche 1 bis 2, wobei der Abstandshalter (30) in Scheibenform mit einem sich verjüngenden Umfangsbereich ausgebildet ist.
  4. Magnetron für einen Mikrowellenherd gemäß einem der Ansprüche 1 bis 3, wobei das Magnetron weiterhin eine zusätzliche Metallbeschichtung (33') an der unteren Außenfläche des Abstandshalters (30) aufweist.
  5. Magnetron für einen Mikrowellenherd gemäß Anspruch 1, wobei der Abstandshalter (30) einen vertikalen Randbereich aufweist, der senkrecht sowohl zur oberen als auch zur unteren Außenfläche des Abstandshalters steht und wobei dementsprechend die Faserdichtung (4) einen Absatz aufweist, der den Abstandshalter (30) stützt.
  6. Magnetron gemäß einem der Ansprüche 1 bis 5, wobei die Metallplatte (33) auf der oberen Außenfläche des Abstandshalters (30) beschichtet ist.
EP19920402719 1991-11-20 1992-10-06 Magnetron für einen Mikrowellenherd Expired - Lifetime EP0543687B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
KR1997491U 1991-11-20
KR910019974 1991-11-20

Publications (2)

Publication Number Publication Date
EP0543687A1 EP0543687A1 (de) 1993-05-26
EP0543687B1 true EP0543687B1 (de) 1996-08-14

Family

ID=19322596

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Application Number Title Priority Date Filing Date
EP19920402719 Expired - Lifetime EP0543687B1 (de) 1991-11-20 1992-10-06 Magnetron für einen Mikrowellenherd

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EP (1) EP0543687B1 (de)
DE (1) DE69212775T2 (de)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105355526A (zh) * 2015-11-21 2016-02-24 安徽华东光电技术研究所 一种小型化收集极的引线封接方法及其封接结构

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4684845A (en) * 1984-05-07 1987-08-04 Hitachi, Ltd. Magnetron cathode assembly with grooved insulating spacer
EP0339374B1 (de) * 1988-04-25 1994-03-02 Matsushita Electronics Corporation Magnetron

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DE69212775D1 (de) 1996-09-19
DE69212775T2 (de) 1997-01-16
EP0543687A1 (de) 1993-05-26

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