EP0247668B1 - Microwave oven having a door-closing safety device - Google Patents
Microwave oven having a door-closing safety device Download PDFInfo
- 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
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- 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
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- 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.
Description
L'invention concerne un four à micro-ondes comprenant un magnétron émettant des micro-ondes à l'intérieur d'une cavité de cuisson qui peut être fermée par une porte mobile, le four mettant en oeuvre l'émission de lumière détectée à travers un diaphragme afin de constituer un dispositif de sécurité qui, en cas d'une mauvaise ou d'une non-fermeture de la porte, empêche le magnétron de fonctionner afin d'éviter une fuite d'énergie micro-ondes.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.
Un four de ce type est connu du document DE 1 236 105 qui décrit un système de fermeture de sécurité d'une porte de four à micro-ondes. Pour cela une bande métallique est reliée à la porte du four. Si la porte est mal fermée cette bande intercepte un rayon lumineux issu d'un émetteur de lumière solidaire de l'encadrement du four. Cette bande présente une petite ouverture de sorte que le rayon lumineux peut traverser cette ouverture et atteindre une cellule photoélectrique lorsque la porte est hermétiquement fermée et autoriser ainsi la mise en marche du magnétron. Mais ce dispositif est très localisé et n'assure qu'une protection réduite. Or à l'usage la fermeture de la porte va peu à peu perdre ses qualités originelles et des fuites d'énergie micro-ondes vont pouvoir apparaître bien qu'en apparence la porte puisse paraître correctement fermée par le dispositif de ce document.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. For this 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. But 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.
De même ce dispositif de sécurité ne traite pas de la situation, où, bien que le dispositif fonctionnant correctement, il subsiste néanmoins des fuites d'énergie micro-ondes car la planéité de la porte a été détériorée. C'est un problème très critique des fours à micro-ondes car les normes de sécurité en vigueur sur ces appareils imposent que les fuites soient très réduites tout autour de l'ouverture de la porte. Il est de plus souhaitable que ces normes restent respectées tout au long de la durée de vie du four. Or à l'usage la porte peut avoir tendance à se déformer ou se déplacer, et ces normes ne sont plus respectées, ce qui peut provoquer une irradiation inadmissible des utilisateurs.Likewise, 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. This is a very critical problem of microwave ovens because the safety standards in force on these devices require that the leaks are very small all around the door opening. It is moreover desirable that these standards remain respected throughout the lifetime of the furnace. However, in use, the door may tend to deform or move, and these standards are no longer respected, which can cause inadmissible irradiation by users.
Le but de l'invention est donc de détecter une quelconque déformation ou déplacement de la porte ou de l'encadrement, et d'agir pour empêcher la mise en fonctionnement du magnétron.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.
Pour cela l'invention telle que définie dans le préambule est remarquable en ce que le faisceau dudit émetteur est guidé vers ledit détecteur par une pluralité de guides de lumière, lesdits guides étant disposés l'un après l'autre tout au long du trajet dudit faisceau de telle façon qu'il existe des espaces entre des guides voisins, les guides de lumière étant solidaires de l'encadrement de la cavité de cuisson sur la majeure partie d'au moins un côté dudit encadrement, et en ce que le four comprend des diaphragmes solidaires de la porte mobile à sa périphérie de telle façon que quand ladite porte est fermée chaque diaphragme est disposé dans l'espace entre deux guides de lumière voisins, chaque diaphragme présentant d'autre part une ouverture telle que le faisceau lumineux traverse toutes les ouvertures lorsque la porte mobile est correctement fermée, et telle que le faisceau lumineux est intercepté par les bords de l'ouverture d'au moins un diaphragme lorsque la porte mobile est incorrectement fermée, ou déformée ou déplacée, afin d'empêcher le magnétron d'être mis en fonctionnement.For this, 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.
Les guides de lumière sont disposés le long de 1, 2, 3 ou 4 côtés de l'encadrement de la cavité de cuisson à l'intérieur de la paroi d'habillage du four. chaque côté, sur sa majeure partie peut recevoir un guide ou plusieurs guides successifs transparents à la lumière, montés de telle sorte que leurs axes optiques soient colinéaires. Ces guides sont par exemple en matière plastique ou en verre. Chaque côté peut être indépendant des autres côtés et disposer de son propre émetteur et de son propre détecteur de lumière. Préférentiellement, on utilise un seul émetteur et un seul détecteur de lumière en assurant la continuité optique du dispositif en disposant, aux coins de l'encadrement de la cavité, un miroir de renvoi qui peut être plan ou préférentiellement concave afin d'opérer une focalisation du faisceau. Ces miroirs peuvent par exemple être en verre ou en métal. On dispose ainsi de un ou plusieurs faisceaux lumineux qui cheminent le long de l'encadrement. A l'aide de ces faisceaux on teste le parallélisme et le bon positionnement de la porte par rapport à l'encadrement en disposant sur la porte un ou plusieurs diaphragmes constitués de plaques percées d'un trou. Ces diaphragmes pénêtrent dans des ouvertures disposées dans l'encadrement de sorte que dans les conditions optimales chaque trou de chaque diaphragme laisse passer le faisceau lumineux. Si par contre une anomalie fait que un seul des diaphragmes est mal positionné, le faisceau de lumière est ainsi intercepté et le récepteur de lumière ne détecte aucun flux lumineux. Cette absence de signal est mise à profit pour empêcher la mise en fonctionnement du magnétron.Bien évidemment les diaphragmes de par leurs dimensions réduites ont leur plein usage pour de faibles déplacements de la porte. Les dimensions du faisceau lumineux déterminent les limites maximales du jeu dans le déplacement de la porte. Le dispositif de sécurité et le magnétron lui-même sont neutralisés par un interrupteur d'ouverture de porte lors des ouvertures de porte correspondant à un usage normal du four.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. With the aid of these beams, 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.
Il est bien évidemment possible d'intervertir la disposition des éléments constitutifs de l'invention et de disposer de diaphragmes solidaires de l'encadrement de porte, l'émetteur, le récepteur et les guides optiques étant fixés, solidairement à la porte.It is obviously possible to reverse the arrangement of the constituent elements of the invention and to have diaphragms integral with the door frame, the transmitter, the receiver and the optical guides being fixed, integrally to the door.
L'invention sera mieux comprise à l'aide des figures suivantes, données à titre d'exemples non limitatifs, qui représentent :
- figure 1 : une vue schématique en coupe d'un des côtés du four comprenant l'encadrement, la porte munie de diaphragmes et les guides de lumière,
- figure 2 : une vue schématique de face de l'encadrement de la cavité de cuisson,
- figure 3 : une vue schématique de détails d'un guide de lumière muni de son propre diaphragme,
- figure 4 : un schéma électrique du dispositif de sécurité selon l'invention.
- Figure 1: a schematic sectional view of one side of the oven including the frame, the door provided with diaphragms and the light guides,
- FIG. 2: a schematic front view of the frame of the cooking cavity,
- FIG. 3: a schematic view of details of a light guide provided with its own diaphragm,
- Figure 4: an electrical diagram of the safety device according to the invention.
La figure 1 représente une vue schématique en coupe d'un des côtés de la cavité de cuisson. Le dessin n'est pas à l'échelle.Figure 1 shows a schematic sectional view of one side of the cooking cavity. this drawing is not to scale.
Cette figure représente un encadrement rigide 10 de cavité de cuisson de four, recouvert par une plaque de protection 9, et une porte 11 mobile autour d'un axe 12. Cette porte 11 comporte des diaphragmes par exemple 13, 14, 15. Chacun de ces diaphragmes comporte un trou 13a, 14a, 15a. Les guides de lumière 16₁, 16₂, 16₃, 16₄ sont fixés rigidement à l'encadrement 10 de sorte que leurs axes optiques soient colinéaires. Un émetteur de lumière 17 émet un faisceau lumineux qui traverse les guides de lumière 16₁, 16₂, 16₃, 16₄ et les trous des diaphragmes 13a, 14a, 15a pour atteindre le détecteur 18. Ces trous ont par exemple 1 mm de diamètre. La porte du four est mobile dans la direction A selon une rotation autour de l'axe 12. Si la porte n'est pas correctement fermée ou si des déformations ont endommagé sa planéité ou sa position ou si des déformations de l'encadrement apparaissent, le faisceau lumineux est intercepté par les bords du diaphragme et ne peut plus traverser les trous. Le détecteur 18 ne détecte alors plus de signal.This figure represents a
La figure 1 représente un côté de l'encadrement de la cavité de cuisson. Il est possible de placer les mêmes éléments sur les quatre côtés de l'encadrement. Mais on peut réduire le nombre d'émetteurs et de récepteurs en plaçant des miroirs de renvoi aux angles de l'encadrement. Ceci est représenté sur la figure 2 selon une vue schématique de face telle qu'elle apparaît lorsque la plaque de protection 9 de la figure 1 a été enlevée. L'encadrement 10 de la cavité de cuisson est entouré sur chaque côté des guides de lumières 16₁ à 16₄, 21₁ à 11₄, 22₁ à 22₄, 23₁ à 23₄. Le faisceau de lumière, qui transite à travers les guides, passe à travers chaque trou percé dans chaque diaphragme fixé sur la porte mobile lorsqu' elle est correctement fermée. Aux coins de l'encadrement le faisceau est dévié à l'aide de miroirs, par exemple les miroirs 24, 26, 28. Ces miroirs peuvent être plans ou préférentiellement concaves pour assurer une focalisation du faisceau. Le faisceau lumineux émis par l'émetteur 17 traverse les guides et les diaphragmes et est dévié par les miroirs pour atteindre le détecteur 18. Le dispositif peut ainsi détecter des déformations ou des déplacements de la porte mobile ou de l'encadrement lui-même.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. This is shown in Figure 2 in a schematic front view as it appears when the
La figure 2 représente une structure avec 16 guides de lumière et trois diaphragmes par côté. Il est bien évidemment possible de mettre un nombre bien plus réduit d'éléments selon la qualité de la protection que l'on désire obtenir.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.
La figure 3 représente une vue schématique du détail d'un guide de lumière disposé en face du trou d'un diaphragme. Dans la position de fermeture correcte, l'axe du guide de lumière 16₂ passe par le centre du trou 13a du diaphragme 13. Pour assurer que le jeu tolérable maximal sur la fermeture de la porte soit de l'ordre du mm, afin que les pertes d'énergie micro-ondes restent en dessous d'un niveau tolérable, il est nécessaire que le diamètre du faisceau lumineux soit de très faible dimension. Ce diamètre est par exemple de 1 mm. Selon la section du guide de lumière 16₂ il peut être nécessaire de réduire la section du faisceau en sortie de guide en mettant à la sortie de chaque guide un autre diaphragme 19. En intervenant sur la section des trous des diaphragmes 13 et 19 on peut ainsi régler la précision que l'on désire obtenir et donc les tolérances de jeu de porte que l'on admet.FIG. 3 represents a schematic view of the detail of a light guide arranged opposite the hole of a diaphragm. In the correct closing position, the axis of the
La figure 4 représente le schéma électrique du dispositif de sécurité selon l'invention. Deux guides seulement sont représentés 16₁, 16₂. L'émetteur 17 est une diode électroluminescente et le récepteur 18 est un phototransistor. Le faisceau peut être intercepté par le diaphragme 13.Figure 4 shows the electrical diagram of the safety device according to the invention. Only two guides are shown 16₁, 16₂. The
Le bloc d'alimentation basse tension 41 du dispositif de l'invention alimente l'émetteur 17 à travers l'interrupteur de porte 42. Celui-ci est ouvert lorsque la porte est ouverte et fermé lorsque la porte est fermée, permettant ainsi à l'émetteur d'émettre un flux lumineux et au dispositif de sécurité d'être opérationnel. Pour éliminer les problèmes de lumière parasite ambiante l'émetteur 17 est de préférence modulé par un circuit de modulation 44 par exemple à 30 KHz selon les techniques habituelles. Le bloc 41 alimente également le phototransistor 18 qui a une résistance 43 dans son circuit d'émetteur.The low voltage power supply 41 of the device of the invention supplies the
Le signal modulé, détecté par le récepteur 18, est démodulé par le circuit de démodulation 45 qui délivre un signal qui excite la bobine 46 d'un relais. Les contacts 47₁ et 47₂ de ce relais sont reliés respectivement à une alarme 49 et au circuit d'alimentation du magnétron 50. Lorsque le détecteur ne reçoit aucun flux lumineux ou un flux inférieur à une valeur seuil prédéterminée, l'alarme est excitée afin de prévenir l'utilisateur. Cette alarme peut être sonore ou visuelle. Lorsque le détecteur reçoit un flux lumineux, c'est le circuit d'alimentation du magnétron qui est excité permettant la mise en fonctionnement du four à micro-ondes. Les circuits électriques du four sont commandés par un interrupteur général 48 pour leur alimentation par le réseau électrique entre les points B et C.The modulated signal, detected by the
Claims (10)
- A microwave oven comprising a magnetron emitting microwaves inside a cooking chamber which can be closed by a movable door (11), the oven employing the emission of light detected through a diaphragm to form a safety device which, if the door is closed incorrectly or is not closed, prevents the magnetron from operating in order to preclude leakage of microwave energy, said oven comprising at least one light emitter (17) and at least one light detector (18), characterized in that the beam of said emitter is guided towards said detector by a plurality of light guides (16₁ to 16₄), said guides being arranged after one another along the entire path of said beam in such a way that spacings are obtained between adjacent guides, the light guides being fixedly connected to the frame (10) of the cooling chamber over the greater part of at least one side of said frame, and in that the oven comprises diaphragms (13, 14, 15) which are fixedly connected to the movable door at its periphery in such a way that when said door is closed each diaphragm is situated in the spacing between two adjacent light guides, each diaphragm further having an aperture (13a, 14a, 15a) such that the light beam passes through all the apertures when the movable door is closed correctly, and such that the light beam is intercepted by the edges of the aperture of at least one diaphragm when the movable door is not closed correctly, or is deformed or offset, in order to prevent the magnetron from being put into operation.
- A microwave oven comprising a magnetron emitting microwaves inside a cooking chamber which can be closed by a movable door (11), the oven employing the emission of light detected through a diaphragm to form a safety device which, if the door is closed incorrectly or is not closed, prevents the magnetron from operating in order to preclude leakage of microwave energy, said oven comprising at least one light emitter (17) and at least one light detector (18), characterized in that the beam of said emitter is guided towards said detector by a plurality of light guides (16₁ to 16₄), said guides being arranged after one another along the entire path of said beam in such a way that spacings are obtained between adjacent guides, the light guides being fixedly connected to the movable door (11) at its periphery over the greater part of at least one of its sides, and in that the oven comprises diaphragms (13, 14, 15) which are fixedly connected to the frame of the cooking chamber in such a way that when said door is closed each diaphragm is situated in the spacing between two adjacent light guides, each diaphragm further having an aperture (13a, 14a, 15a) such that the light beam passes through all the apertures when the movable door is closed correctly, and such that the light beam is intercepted by the edges of the aperture of at least one diaphragm when the movable door is not closed corteclly, or is deformed or offset, in order to prevent the magnetron from being put into operation.
- A microwave oven as claimed in Claim 1 or 2, characterized in that a light emitter (17) is associated with a light detector (18) for each side of the frame (10) of the oven door.
- A microwave oven as claimed in Claim 1 or 2, characterized in that the path of the light beam between the light emitter (17) and light detector (18) is deflected by intermediate mirrors (24) (26) (28) at the corners of the oven.
- A microwave oven as claimed in Claim 4, characterized in that the intermediate mirror is concave to focus the beam.
- A microwave oven as claimed in any one of the Claims 1 to 5, characterized in that the diameter of the hole (13a) (14a) (15a) in each diaphragm is substantially 1 mm.
- A microwave oven as claimed in any one of the Claims 1 to 6, characterized in that the light emitter (17) is a light-emitting diode.
- A microwave oven as claimed in any one of Claims 1 to 7, characterized in that the light detector (18) is a photo-transistor.
- A microwave oven as claimed in any one of Claims 1 to 8, characterized in that the output of at least one light guide comprises another diaphragm (19) with a hole limiting the dimension of the beam.
- A microwave oven as claimed in any one of Claims 1 to 9, characterized in that the light detector actuates an audible or visible alarm when incorrect operation is detected.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR8607391A FR2599127B1 (en) | 1986-05-23 | 1986-05-23 | MICROWAVE OVEN HAVING A DOOR CLOSING SECURITY DEVICE |
| FR8607391 | 1986-05-23 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| EP0247668A1 EP0247668A1 (en) | 1987-12-02 |
| EP0247668B1 true EP0247668B1 (en) | 1991-08-07 |
Family
ID=9335555
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP87200890A Expired - Lifetime EP0247668B1 (en) | 1986-05-23 | 1987-05-14 | Microwave oven having a door-closing safety device |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US4760229A (en) |
| EP (1) | EP0247668B1 (en) |
| JP (1) | JPS62192108U (en) |
| DE (1) | DE3771931D1 (en) |
| FR (1) | FR2599127B1 (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3915541C2 (en) * | 1989-05-12 | 1994-02-03 | Vogt Electronic Ag | Arrangement for the electronic door monitoring of a microwave oven |
| 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 (en) * | 1992-06-16 | 1993-12-27 | Toshiba Corp | Cooker |
| 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 (en) * | 2010-11-08 | 2012-05-10 | BSH Bosch und Siemens Hausgeräte GmbH | household appliance |
Family Cites Families (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1236105B (en) * | 1962-02-12 | 1967-03-09 | Siemens Elektrogeraete Gmbh | HF radiation source with automatic shutdown of HF radiation |
| 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 (en) * | 1978-05-18 | 1979-11-22 | Moto Meter Ag | Light barrier system for electrically operated car windows - with each light barrier operating at its own frequency which is different from others |
| US4565967A (en) * | 1982-06-21 | 1986-01-21 | Whirlpool Corporation | Method and apparatus for testing microwave ovens |
| DE3236290C2 (en) * | 1982-09-30 | 1985-08-08 | Bosch-Siemens Hausgeräte GmbH, 7000 Stuttgart | Device for monitoring the closed status of doors on microwave ovens |
-
1986
- 1986-05-23 FR FR8607391A patent/FR2599127B1/en not_active Expired
-
1987
- 1987-05-14 EP EP87200890A patent/EP0247668B1/en not_active Expired - Lifetime
- 1987-05-14 DE DE8787200890T patent/DE3771931D1/en not_active Expired - Lifetime
- 1987-05-20 JP JP1987074490U patent/JPS62192108U/ja active Pending
- 1987-05-21 US US07/053,164 patent/US4760229A/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| FR2599127A1 (en) | 1987-11-27 |
| US4760229A (en) | 1988-07-26 |
| DE3771931D1 (en) | 1991-09-12 |
| FR2599127B1 (en) | 1989-09-22 |
| JPS62192108U (en) | 1987-12-07 |
| EP0247668A1 (en) | 1987-12-02 |
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