EP0247668B1 - Mikrowellenofen mit einer Türsicherheitsverschlussvorrichtung - Google Patents

Mikrowellenofen mit einer Türsicherheitsverschlussvorrichtung Download PDF

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Publication number
EP0247668B1
EP0247668B1 EP87200890A EP87200890A EP0247668B1 EP 0247668 B1 EP0247668 B1 EP 0247668B1 EP 87200890 A EP87200890 A EP 87200890A EP 87200890 A EP87200890 A EP 87200890A EP 0247668 B1 EP0247668 B1 EP 0247668B1
Authority
EP
European Patent Office
Prior art keywords
light
door
oven
closed
diaphragm
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
EP87200890A
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English (en)
French (fr)
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EP0247668A1 (de
Inventor
Michel Steers
Jean-Pierre Hazan
Gilles Delmas
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.)
Laboratoires dElectronique Philips SAS
Koninklijke Philips NV
Original Assignee
Laboratoires dElectronique Philips SAS
Philips Gloeilampenfabrieken NV
Koninklijke Philips Electronics NV
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 Laboratoires dElectronique Philips SAS, Philips Gloeilampenfabrieken NV, Koninklijke Philips Electronics NV filed Critical Laboratoires dElectronique Philips SAS
Publication of EP0247668A1 publication Critical patent/EP0247668A1/de
Application granted granted Critical
Publication of EP0247668B1 publication Critical patent/EP0247668B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/64—Heating using microwaves
    • H05B6/6414—Aspects relating to the door of the microwave heating apparatus
    • H05B6/6417—Door interlocks of the microwave heating apparatus and related circuits

Definitions

  • the invention relates to a microwave oven comprising a magnetron emitting microwaves inside a cooking cavity which can be closed by a movable door, the oven implementing the emission of light detected through a diaphragm in order to constitute a safety device which, in the event of a bad or non-closing of the door, prevents the magnetron from functioning in order to avoid a leak of microwave energy.
  • An oven of this type is known from document DE 1 236 105 which describes a system for closing the safety of a microwave oven door.
  • a metal strip is connected to the oven door. If the door is not properly closed, this strip intercepts a light beam from a light emitter attached to the oven frame.
  • This strip has a small opening so that the light ray can pass through this opening and reach a photoelectric cell when the door is hermetically closed and thus authorize the activation of the magnetron.
  • this device is very localized and provides only reduced protection. However, in use, closing the door will gradually lose its original qualities and leaks of microwave energy will be able to appear, although in appearance the door may appear properly closed by the device of this document.
  • this safety device does not deal with the situation, where, although the device functions correctly, there are nevertheless leaks of microwave energy because the flatness of the door has been deteriorated.
  • the door may tend to deform or move, and these standards are no longer respected, which can cause inadmissible irradiation by users.
  • the object of the invention is therefore to detect any deformation or displacement of the door or of the frame, and to act to prevent the magnetron from operating.
  • the invention as defined in the preamble is remarkable in that the beam of said transmitter is guided towards said detector by a plurality of light guides, said guides being arranged one after the other along the path of said bundle so that there are spaces between neighboring guides, the light guides being integral with the frame of the cooking cavity on the major part of at least one side of said frame, and in that the oven comprises diaphragms integral with the movable door at its periphery so that when said door is closed each diaphragm is arranged in the space between two neighboring light guides, each diaphragm having on the other hand an opening such that the light beam passes through all the openings when the movable door is properly closed, and such that the light beam is intercepted by the edges of the opening of at least one diaphragm when e the movable door is incorrectly closed, or deformed or moved, in order to prevent the magnetron from being put into operation.
  • the light guides are arranged along 1, 2, 3 or 4 sides of the frame of the cooking cavity inside the oven lining wall.
  • each side on its major part can receive a guide or several successive guides transparent to light, mounted in such a way so that their optical axes are collinear.
  • These guides are for example made of plastic or glass.
  • Each side can be independent of the other sides and have its own transmitter and its own light detector. Preferably, a single transmitter and a single detector are used.
  • light by ensuring the optical continuity of the device by arranging, at the corners of the frame of the cavity, a deflection mirror which may be plane or preferably concave in order to focus the beam.
  • These mirrors can for example be made of glass or metal. There are thus one or more light beams which run along the frame.
  • the parallelism and the correct positioning of the door with respect to the frame are tested by placing on the door one or more diaphragms made up of plates pierced with a hole. These diaphragms penetrate into openings arranged in the frame so that under the optimal conditions each hole of each diaphragm lets the light beam pass. If, however, an anomaly causes only one of the diaphragms to be positioned incorrectly, the light beam is thus intercepted and the light receiver does not detect any light flux. This lack of signal is used to prevent the magnetron from operating. Obviously, the diaphragms, due to their reduced dimensions, are fully used for small movements of the door. The dimensions of the light beam determine the maximum limits of the clearance in the movement of the door.
  • the safety device and the magnetron itself are deactivated by a door opening switch during door openings corresponding to normal use of the oven.
  • Figure 1 shows a schematic sectional view of one side of the cooking cavity. This drawing is not to scale.
  • This figure represents a rigid frame 10 of the oven cooking cavity, covered by a protective plate 9, and a door 11 movable around an axis 12.
  • This door 11 comprises diaphragms for example 13, 14, 15. Each of these diaphragms have a hole 13a, 14a, 15a.
  • the light guides 161, 162, 163, 164 are rigidly fixed to the frame 10 so that their optical axes are collinear.
  • a light emitter 17 emits a light beam which passes through the light guides 161, 162, 163, 164 and the holes in the diaphragms 13a, 14a, 15a to reach the detector 18. These holes are, for example, 1 mm in diameter.
  • the oven door is movable in direction A according to a rotation around the axis 12.
  • the light beam is intercepted by the edges of the diaphragm and can no longer pass through the holes.
  • the detector 18 then no longer detects a signal.
  • Figure 1 shows one side of the frame of the cooking cavity.
  • the same elements can be placed on all four sides of the frame. However, the number of transmitters and receivers can be reduced by placing return mirrors at the corners of the frame.
  • Figure 2 in a schematic front view as it appears when the protective plate 9 of the figure 1 has been removed.
  • the frame 10 of the cooking cavity is surrounded on each side of the light guides 161 to 164, 211 to 114, 221 to 224, 231 to 234.
  • the light beam which passes through the guides, passes through each hole drilled in each diaphragm attached to the movable door when it is properly closed.
  • the beam is deflected using mirrors, for example mirrors 24, 26, 28.
  • These mirrors can be planar or preferably concave to ensure focusing of the beam.
  • the light beam emitted by the emitter 17 passes through the guides and the diaphragms and is deflected by the mirrors to reach the detector 18.
  • the device can thus detect deformations or displacements of the movable door or of the frame itself.
  • Figure 2 shows a structure with 16 light guides and three diaphragms per side. It is obviously possible to put a much smaller number of elements depending on the quality of the protection that one wishes to obtain.
  • FIG. 3 represents a schematic view of the detail of a light guide arranged opposite the hole of a diaphragm.
  • the axis of the light guide 162 passes through the center of the hole 13 a of the diaphragm 13.
  • the diameter of the light beam must be very small. This diameter is for example 1 mm.
  • FIG. 4 shows the electrical diagram of the safety device according to the invention. Only two guides are shown 161, 162.
  • the transmitter 17 is a light emitting diode and the receiver 18 is a phototransistor.
  • the beam can be intercepted by the diaphragm 13.
  • the low voltage power supply 41 of the device of the invention supplies the transmitter 17 through the door switch 42.
  • the latter is open when the door is opened and closed when the door is closed, thus allowing the 'emitter to emit a light flux and the safety device to be operational.
  • the emitter 17 is preferably modulated by a modulation circuit 44 for example at 30 KHz according to the usual techniques.
  • the block 41 also supplies the phototransistor 18 which has a resistor 43 in its transmitter circuit.
  • the modulated signal, detected by the receiver 18, is demodulated by the demodulation circuit 45 which delivers a signal which excites the coil 46 of a relay.
  • the contacts 471 and 472 of this relay are respectively connected to an alarm 49 and to the magnetron 50 supply circuit.
  • the alarm When the detector receives no light flux or a flux below a predetermined threshold value, the alarm is activated in order to notify the user. This alarm can be audible or visual.
  • the detector receives a luminous flux, it is the magnetron supply circuit which is excited allowing the microwave oven to operate.
  • the electric circuits of the oven are controlled by a general switch 48 for their supply by the electric network between points B and C.

Claims (10)

  1. Mikrowellenofen mit eine Magnetron, das im Innern eines Kochraums Mikrowellen ausstrahlt, wobei dieser Kochraum mittels einer beweglichen Tür (11) abgeschlossen sein kann, wobei Gebrauch gemacht wird von der Ausstrahlung mittels einer Blende detektierten Lichtes eine Sicherheitsvorrichtung zu bilden, die wenn die Tür nicht einwandfrei oder überhaupt nicht geschlossen ist, das Magnetron verhindert zu funktionieren, um ein Weglecken von Mikrowellen zu vermeiden, wobei dieser Ofen mindestens einen Lichtstrahler (17) und mindestens einen Lichtdetektor (18) aufweist, dadurch gekennzeichnet, daß der vom genannten Strahler herrührende Strahl über eine Anzahl Lichtwellenleiter (16₁ bis 16₄) dem genannten Detektor zugeführt wird, wobei diese Lichtwellenleiter derart hintereinander in der Strecke des genannten Strahles vorgesehen sind, daß es zwischen benachbarten Leitern einen Zwischenraum gibt, wobei die Lichtwellenleiter über den größten Teil mindestens einer Seite des genannten Rahmens (10) des Kochraumes angeordnet sind, und daß der Ofen einen Teil mit der beweglichen Tür bildende Blenden (13, 14, 15) aufweist, derart, daß wenn diese Tür geschlossen ist, jede Blende in dem Raum zwischen zwei benachbarten Lichtwellenleitern liegt, wobei jede Blende andererseits eine Öffnung (13a, 14a, 15a) aufweist, und zwar derart, daß der Lichtstrahl alle Öffnungen durchquert, wenn die bewegliche Tür einwandfrei geschlossen ist, und daß der Lichtstrahl durch die Ränder der Öffnung mindestens einer Blende unterbrochen wird, wenn die bewegliche Tür nicht einwandfrei geschlossen, verformt oder verschoben ist, damit vermieden wird, daß das Magnetron eingeschaltet wird.
  2. Mikrowellenofen mit einem Magnetron, das im Innern eines Kochraums Mikrowellen ausstrahlt, wobei dieser Kochraum mittels einer beweglichen Tür (11) abgeschlossen sein kann, wobei Gebrauch gemacht wird von der Ausstrahlung mittels einer Blende detektierten Lichtes eine Sicherheitsvorrichtung zu bilden, die wenn die Tür nicht einwandfrei oder überhaupt nicht geschlossen ist, das Magnetron verhindert zu funktionieren, um ein Weglecken von Mikrowellen zu vermeiden, wobei dieser Ofen mindestens einen Lichtstrahler (17) und mindestens einen Lichtdetektor (18) aufweist, dadurch gekennzeichnet, daß der vom genannten Strahler herrührende Strahl über eine Anzahl Lichtwellenleiter (16₁ bis 16₄) dem genannten Detektor zugeführt wird, wobei diese Lichtwellenleiter derart hintereinander in der Strecke des genannten Strahles vorgesehen sind, daß es zwischen benachbarten Leitern einen Zwischenraum gibt, wobei die Lichtwellenleiter einen Teil mit der beweglichen Tür (11) bilden und zwar am Rand über den größten Teil mindestens einer der Seiten, und daß der Ofen einen Teil mit dem Rahmen des Kochraumes bildende Blenden (13, 14, 15) aufweist, derart, daß wenn diese Tür geschlossen ist, jede Blende in dem Raum zwischen zwei benachbarten Lichtwellenleitern liegt, wobei jede Blende andererseits eine Öffnung (13a, 14a, 15a) aufweist, und zwar derart, daß der Lichtstrahl alle Öffnungen durchquert, wenn die bewegliche Tür einwandfrei geschlossen ist, und daß der Lichtstrahl durch die Ränder der Öffnung mindestens einer Blende unterbrochen wird, wenn die bewegliche Tür nicht einwandfrei geschlossen, verformt oder verschoben ist, damit vermieden wird, daß das Magnetron eingeschaltet wird.
  3. Mikrowellenofen nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß für jede Seite des Rahmens (10) der Ofentür ein mit einem Lichtdetektor (18) zusammenarbeitender Lichtstrahler (17) vorgesehen ist.
  4. Mikrowellenofen nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß die Strecke des Lichtstrahles zwischen dem Lichtstrahler (17) und dem Lichtdetektor (18) an den Ecken des Ofens mittels Umlenkspiegel (24) (26) (28) umgelenkt wird.
  5. Mikrowellenofen nach Anspruch 4, dadurch gekennzeichnet, daß der Umlenkspiegel zur Gewährleistung einer Fokussierung des Strahles konkav ist.
  6. Mikrowellenofen nach einem der vorstehenden Ansprüche, dadurch gekennzeichnet, daß die Öffnung (13a) (14a) (15a) in jeder Blende einen Durchmesser von etwa 1 mm hat.
  7. Mikrowellenofen nach einem der vorstehenden Ansprüche, dadurch gekennzeichnet, daß der Lichtstrahler (17) eine Leuchtdiode ist.
  8. Mikrowellenofen nach einem der vorstehenden Ansprüche, dadurch gekennzeichnet, daß der Lichtdetektor (18) ein Phototransistor ist.
  9. Mikrowellenofen nach einem der vorstehenden Ansprüche, dadurch gekennzeichnet, daß der Ausgang mindestens eines Lichtwellenleiters eine andere Blende (19) aufweist, die mit einer Öffnung versehen ist, die die Größe des Strahles beschränkt.
  10. Mikrowellenofen nach einem der vorstehenden Ansprüche, dadurch gekennzeichnet, daß der Lichtdetektor ein akustisches oder visuelles Alarmsignal auslöst, wenn ein nicht einwandfreies Funktionieren detektiert wird.
EP87200890A 1986-05-23 1987-05-14 Mikrowellenofen mit einer Türsicherheitsverschlussvorrichtung Expired - Lifetime EP0247668B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8607391 1986-05-23
FR8607391A FR2599127B1 (fr) 1986-05-23 1986-05-23 Four a micro-ondes comportant un dispositif de securite de fermeture de porte

Publications (2)

Publication Number Publication Date
EP0247668A1 EP0247668A1 (de) 1987-12-02
EP0247668B1 true EP0247668B1 (de) 1991-08-07

Family

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EP87200890A Expired - Lifetime EP0247668B1 (de) 1986-05-23 1987-05-14 Mikrowellenofen mit einer Türsicherheitsverschlussvorrichtung

Country Status (5)

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US (1) US4760229A (de)
EP (1) EP0247668B1 (de)
JP (1) JPS62192108U (de)
DE (1) DE3771931D1 (de)
FR (1) FR2599127B1 (de)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3915541C2 (de) * 1989-05-12 1994-02-03 Vogt Electronic Ag Anordnung zur elektronischen Türüberwachung eines Mikrowellenherdes
US5132503A (en) * 1989-12-30 1992-07-21 Samsung Electronics Co., Ltd. Apparatus for detecting the open or closed condition of a microwave oven door
JPH05346235A (ja) * 1992-06-16 1993-12-27 Toshiba Corp 調理装置
US7145118B1 (en) * 2005-08-22 2006-12-05 Ming-Jing Wu Microwave oven protective circuit arrangement
US7847256B2 (en) * 2008-05-30 2010-12-07 Gm Global Technology Operations, Inc. Secure enclosure
DE102010043537A1 (de) * 2010-11-08 2012-05-10 BSH Bosch und Siemens Hausgeräte GmbH Haushaltsgerät

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Publication number Priority date Publication date Assignee Title
DE1236105B (de) * 1962-02-12 1967-03-09 Siemens Elektrogeraete Gmbh HF-Strahlungsherd mit selbsttaetiger Abschaltung der HF-Strahlung
US3604783A (en) * 1969-06-30 1971-09-14 Dca Food Ind Microwave cavity viewers
US3651300A (en) * 1971-01-25 1972-03-21 Matsushita Electric Ind Co Ltd Microwave heating apparatus with radiation control and monitoring
US3749875A (en) * 1972-08-07 1973-07-31 Gen Electric Microwave oven leakage detection system
US3746824A (en) * 1972-08-07 1973-07-17 Gen Electric Microwave oven leakage radiation detecting device
US3955060A (en) * 1974-08-14 1976-05-04 Philip Morris Incorporated Microwave oven construction
CS183276B1 (en) * 1976-01-20 1978-06-30 Viktor Kraus Safety device for the doors of mass coneyances
US4065655A (en) * 1976-05-17 1977-12-27 Canadian Patents And Development Limited Microwave leakage indicator strip
US4275294A (en) * 1977-09-28 1981-06-23 Fibun B.V. Security system and strip or strand incorporating fibre-optic wave-guide means therefor
DE2821681A1 (de) * 1978-05-18 1979-11-22 Moto Meter Ag Lichtschrankensystem
US4565967A (en) * 1982-06-21 1986-01-21 Whirlpool Corporation Method and apparatus for testing microwave ovens
DE3236290C2 (de) * 1982-09-30 1985-08-08 Bosch-Siemens Hausgeräte GmbH, 7000 Stuttgart Vorrichtung zum Überwachen des Schließzustandes von Türen an Mikrowellenöfen

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Publication number Publication date
JPS62192108U (de) 1987-12-07
US4760229A (en) 1988-07-26
EP0247668A1 (de) 1987-12-02
FR2599127B1 (fr) 1989-09-22
FR2599127A1 (fr) 1987-11-27
DE3771931D1 (de) 1991-09-12

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