EP1836713B1 - Microsystem with integrated reluctant magnetic circuit - Google Patents

Microsystem with integrated reluctant magnetic circuit Download PDF

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Publication number
EP1836713B1
EP1836713B1 EP06707675A EP06707675A EP1836713B1 EP 1836713 B1 EP1836713 B1 EP 1836713B1 EP 06707675 A EP06707675 A EP 06707675A EP 06707675 A EP06707675 A EP 06707675A EP 1836713 B1 EP1836713 B1 EP 1836713B1
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EP
European Patent Office
Prior art keywords
circuit
movable contact
magnetic
membrane
current
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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.)
Not-in-force
Application number
EP06707675A
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German (de)
French (fr)
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EP1836713A1 (en
Inventor
Laurent Chiesi
Christian Bataille
Sylvain Paineau
Caroline Coutier
Amalia Garnier
Benoit Grappe
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Schneider Electric Industries SAS
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Schneider Electric Industries SAS
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Priority claimed from FR0550085A external-priority patent/FR2880729B1/en
Priority claimed from FR0550666A external-priority patent/FR2883274B1/en
Application filed by Schneider Electric Industries SAS filed Critical Schneider Electric Industries SAS
Publication of EP1836713A1 publication Critical patent/EP1836713A1/en
Application granted granted Critical
Publication of EP1836713B1 publication Critical patent/EP1836713B1/en
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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H7/00—Devices for introducing a predetermined time delay between the initiation of the switching operation and the opening or closing of the contacts
    • H01H7/16—Devices for ensuring operation of the switch at a predetermined point in the ac cycle
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H1/00—Contacts
    • H01H1/50—Means for increasing contact pressure, preventing vibration of contacts, holding contacts together after engagement, or biasing contacts to the open position
    • H01H1/54—Means for increasing contact pressure, preventing vibration of contacts, holding contacts together after engagement, or biasing contacts to the open position by magnetic force
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H50/00—Details of electromagnetic relays
    • H01H50/005—Details of electromagnetic relays using micromechanics
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H50/00—Details of electromagnetic relays
    • H01H50/005—Details of electromagnetic relays using micromechanics
    • H01H2050/007—Relays of the polarised type, e.g. the MEMS relay beam having a preferential magnetisation direction

Definitions

  • the present invention relates to a microsystem integrating a reluctant magnetic circuit.
  • This reluctant magnetic circuit makes it possible in particular, by creating an additional contact force, to be able to make an opening of an electric circuit without generating an electric arc.
  • the patent US 4,427,957 discloses a switching device comprising a magnetic circuit consisting of a movable part consisting of a pivoting blade and a fixed part. A coil is wound around the fixed part of the magnetic circuit.
  • An electrical circuit for supplying a load comprises in particular an electrical contact piece integral with the pivoting blade and initially spaced apart from a second electrical contact piece. The first electrical contact piece also acts as a mechanical spring for the pivoting blade.
  • the magnetic circuit Upon passage of a current in the coil, the magnetic circuit is magnetized and generates a first attraction force to attract the pivoting blade.
  • the blade pivots to the connection between the two electrical contact parts, causing the closure of the electrical circuit but also that of the magnetic circuit.
  • the first attraction force is canceled. Only the additional force of attraction keeps the blade in the closed position of the circuit. Since the intensity of this force follows the oscillations of the current through the electric circuit, it takes a value of zero to one given moment. When the current reaches a value below a threshold value, the additional magnetic force becomes less than the mechanical force of return exerted by the spring on the pivoting blade. Under the action of this mechanical force, the pivoting blade deviates from the closed position which opens the electrical circuit.
  • the current threshold value is for example close to zero, which makes it possible to cut the circuit when the current is low and thus to avoid the generation of an electric arc.
  • the mechanical restoring force must be large enough to take off the contacts, generate a magnetic force of the same order of magnitude with a current flowing in a turn does not seem suitable for threshold currents of a few milliamperes.
  • the object of the invention is to propose a microsystem making it possible to respond to the different requirements defined above, in which the breaking of the circuit with a current having a value lower than a threshold value is reliable and perfectly stable over time.
  • the additional contact force generated is proportional to the square of the intensity of the current flowing through the microactuator. This force therefore follows successive positive oscillations.
  • the device according to the invention is a question of directly opposing magnetic forces between them, that is to say the magnetic torque generated by the field of the excitation coil against the main contact force generated by the first magnetic field and the contact force additional generated during the passage of the current in the electrical circuit. It is therefore easier to adjust the level of the threshold current because the level of forces involved is similar.
  • the magnetic forces generated are independent of the wear phenomena of the microsystem and variations in its assembly process.
  • the movable contact piece is bistable.
  • the first magnetic field is permanent and maintains the membrane in each of its positions.
  • the second magnetic field created by the excitation coil is only transient and is only activated for the tilting of the membrane from one of its positions to the other of its positions.
  • the first magnetic field is uniform and oriented perpendicularly to the substrate.
  • the excitation coil is of the solenoid type and it surrounds the substrate and the movable contact piece.
  • the threshold value corresponds to the value of intensity of appearance of an electric arc.
  • the ferromagnetic layer forms with a ferromagnetic reinforcement circuit the magnetic circuit reluctant during the passage of the alternating current in the electric circuit.
  • the magnetic reinforcement circuit is integrated in the substrate.
  • the ferromagnetic reinforcement circuit consists of two symmetrical wings joined by a perpendicular central core, defining a U-shaped cross section.
  • the ferromagnetic reinforcement circuit is oriented so as, in its longitudinal direction, to be parallel to the direction followed by the current when the electric circuit is closed.
  • the wings of the ferromagnetic reinforcement circuit comprise two surfaces each defining an air gap with a parallel surface of the ferromagnetic layer of the movable contact piece located vis-a-vis.
  • the movable contact piece consists of a ferromagnetic membrane pivotally mounted on the substrate and carrying a movable contact adapted in the closed position to electrically connect two fixed conductive tracks arranged on the substrate for closing the electrical circuit.
  • the principle of the invention consists in integrating in a switch electrical apparatus of an electrical circuit a reluctant magnetic circuit to provide the aforementioned advantages.
  • a reluctant magnetic circuit created by the passage of an alternating current in the closed electrical circuit allows applying to the movable contact piece an additional contact or crushing force F '.
  • the intensity of the additional contact force F ' varies as a function of the intensity of the alternating current flowing in the electric circuit and follows successive positive oscillations ( figure 8 ). More specifically, the intensity of this additional contact force F 'is proportional to the square of the current 1 passing through the switch when the reluctant magnetic circuit is not saturated.
  • the invention consists in using the variations of this additional contact force F 'to allow the opening of the electric circuit when the current is at an intensity lower than a threshold value.
  • This threshold value may correspond to the intensity of appearance of an electric arc.
  • the additional contact force F ' may make it possible to prevent the switch from opening as long as the current flowing in it is greater than the threshold current.
  • This threshold value is, for example, 0.2 Ampere.
  • the main contact force F is generated by magnetic or electromagnetic closure means.
  • the opening force is generated by electromagnetic opening means.
  • a microsystem may be a device comprising at least one microactuator that can be manufactured using MEMS type technologies or conventional PCB or kapton PCB technologies.
  • a microactuator such as that described below is a microswitch or microswitch current used in a micro-contactor, a micro-relay or a micro-reed.
  • a microactuator such as that described below is a microswitch or microswitch current used in a micro-contactor, a micro-relay or a micro-reed.
  • microactuator we will use the general term "microactuator" to refer to these different applications.
  • a microsystem may comprise a microactuator 2 mounted on a flat surface 30 of a substrate 3 made of materials such as silicon, glass, ceramics or in the form of printed circuits.
  • the substrate 3 carries on its surface 30, for example, at least two identical planar conductive tracks 31, 32 spaced apart and intended to be electrically connected in order to obtain the closure of the electrical circuit.
  • the magnetic microactuator 2 carries at least one movable contact 21 capable of effecting the electrical junction between the two tracks 31, 32 when the microactuator 2 is activated.
  • the electrical circuit is closed, the current I follows a direction located in the plane of the conductive tracks 31, 32.
  • Such a microactuator 2 is provided with a movable contact piece carrying the movable contact 21 and consisting of a membrane 20 having a longitudinal axis (A) connected by one of its ends to an anchor stud 23 secured to the substrate 3 by means of two link arms 22a, 22b.
  • the movable contact 21 is for example formed on the membrane 20 near the free end of the membrane 20 and faces the surface 30 of the substrate 3.
  • the membrane 20 consists for example of a layer 200 ( Figures 1 and 2 ) of ferromagnetic material having on its surface facing the substrate 3 a recess in which is disposed the contact 21.
  • the microactuator 2 described in the invention can be realized by a planar duplication technology of MEMS (Micro Electro-Mechanical System) type. Indeed, the realization by deposition of successive layers in an iterative process lends itself well to the manufacture of such objects.
  • the membrane 20 as well as the arms 22a, 22b are for example derived from the same layer of ferromagnetic material.
  • the connecting arms 22a, 22b and a lower layer of the membrane 20 may be derived from a metal layer. A layer of a ferromagnetic material is deposited on this metal layer to generate the part 20.
  • Such a configuration can make it possible to optimize the mechanical properties of the linking arms 22a, 22b by using, to enable the pivoting of the membrane 20, a material which is mechanically more suitable than the ferromagnetic material.
  • the metal layer can act as a contact for closing an electrical circuit.
  • the ferromagnetic material is for example of the soft magnetic type and can be for example an alloy of iron and nickel ("permalloy" Ni 80 Fe 20 ).
  • the membrane 20 is pivotable relative to the substrate 3 along an axis (P) parallel to the axis described by the contact points of the membrane 20 with the conductive tracks and perpendicular to the longitudinal axis (A) of the membrane 20.
  • the connecting arms 22a, 22b form an elastic connection between the membrane 20 and the anchor stud 23. In such a configuration, the pivoting of the membrane 20 is thus obtained by bending the connecting arms 22a, 22b.
  • An electromagnet is able to drive by magnetic effect the pivoting movement of the membrane 20 between at least two positions, a closed position of the electrical circuit and an open position of the electric circuit.
  • Another magnetic field generated for example by a permanent magnet or an electromagnet can be used to apply a main contact force F to the membrane 20 in its closed position.
  • the membrane 20 is therefore possible to pivot the membrane 20 about its pivot axis (P) by subjecting the membrane 20 to a magnetic field produced by an external excitation coil 6 solenoid type or planar.
  • the membrane 20 is therefore able to take two distinct extreme positions. With reference to Figures 6A to 6C in a first extreme position ( Figure 6C ), the end of the membrane 20 carrying the contact 21 is raised and does not bear against the conductive tracks 31, 32. The electrical circuit is open. In its second extreme position ( Figures 6A and 6B ), the end of the membrane 20 carrying the contact 21 is in abutment against the conductive tracks 31, 32. In this second position, the electrical circuit is closed.
  • a first magnetic field B 0 preferably as uniform as possible, is applied to the microactuator 2.
  • This first magnetic field B 0 has field lines perpendicular to the surface 30 of the substrate 3. As shown in FIGS. Figures 6A to 6C , the field lines of this first magnetic field B 0 are directed towards the surface 30 of the substrate 3.
  • This first magnetic field B 0 can be generated by a permanent magnet or an electromagnet.
  • a magnetic circuit having as its magnetic source a permanent magnet or an electromagnetic coil 5 ' may be used to create this first magnetic field B 0 .
  • this magnetic circuit consists of a permanent magnet ( Figure 7A ) or a 5 'electromagnetic coil ( Figure 7B ) and two air gap pieces 50, 51 arranged parallel to each other on either side of the permanent magnet or the coil 5 'and between which the first magnetic field B 0 is generated.
  • the use of such a magnetic circuit makes it possible to generate a first uniform magnetic field B 0 in the gap.
  • An electromagnet comprising an external excitation coil 6 of the solenoid type as represented in FIG. figure 5 , connected to a current source, surrounds the substrate 3 and the microactuator 2 supported by the substrate 3.
  • the microactuator 2 is placed in the center of the excitation coil 6, in the central channel of the coil 6.
  • the passage a current in the excitation coil 6 generates a magnetic field direction parallel to the substrate 3 and perpendicular to the axis of pivoting (P) of the membrane to control the pivoting of the membrane 20 of one of its positions towards the other of his positions.
  • the direction of the current flowing through the excitation coil 6 decides the pivoting of the membrane 20 towards one or other of its extreme positions.
  • the solenoid-type excitation coil 6 may be manufactured by printed circuit techniques or by winding a copper wire.
  • the microsystem can comprise several microactuators organized in a matrix and subjected to the influence of the first magnetic field B 0 and that of the second temporary magnetic field created by the coil 6 to control the switching of the microactuators.
  • the matrix is placed in the center of the excitation coil 6.
  • the substrate 3 supporting the microactuator 2 and surrounded by the solenoid excitation coil 6 is placed under the effect of the first magnetic field B 0 , for example in the gap of the magnetic circuit described above in connection with the Figures 7A and 7B .
  • the first magnetic field B 0 initially generates a magnetic component BP 0 in the membrane 20 along its longitudinal axis (A).
  • the magnetic torque resulting from the first magnetic field B 0 and the component BP 0 generated in the membrane 20 holds the membrane 20 in one of its extreme positions, for example in the second extreme position ( Figure 6A ).
  • the contact 21 carried by the membrane 20 electrically connects the two tracks 31, 32 and the conductive circuit is closed.
  • the first extreme position ( Figure 6C )
  • the movable contact 21 of the membrane 20 is raised and spaced from the fixed contacts 31, 32.
  • the electrical circuit is open.
  • the invention consists in creating a reluctant magnetic circuit by using the ferromagnetic layer 200 of the membrane 20 and by integrating into the substrate 3 a reinforcement circuit 4 also made of ferromagnetic material.
  • the ferromagnetic material used for this reinforcing circuit 4 and for the layer 200 of the membrane 20 is, for example, of the soft magnetic type and may be a FeNi type alloy ("permalloy").
  • the reinforcing circuit 4 is disposed under the two conductive tracks 31, 32 and extends at the space between the two tracks 31, 32 to act on the membrane 20 above, in the vertical. Seen from the side, this reinforcing circuit 4 has the shape of a U ( figure 2 ), and therefore has two symmetrical parallel wings 41, 42 joined by a central core 40 perpendicular to the two wings 41, 42. The central core 40 is disposed under the tracks 31, 32 and the two conductive wings 41, 42 extend. perpendicularly on both sides of the two tracks 31, 32 conductors.
  • the reinforcing circuit 4 is oriented so as, in its longitudinal direction, to be parallel to the direction followed by the current I in the conductive tracks 31, 32 when the electric circuit is closed.
  • the wings 41, 42 of the reinforcement circuit 4 each terminate in a surface 43 situated in a plane parallel to the plane of the conductive tracks 31, 32 so as to define each an air gap E 1 , E 2 with a parallel surface of the ferromagnetic layer. 200 of the membrane 20 located vis-à-vis.
  • the two conductive tracks 31, 32 are slightly raised relative to the surfaces 43 of the wings 41, 42 so as to always leave a gap E 1 , E 2 residual between the reinforcing circuit and the ferromagnetic layer 200 of the membrane 20 even when the contact 21 of the membrane 20 is pressed against the tracks 31, 32 conductors.
  • the actuation of the membrane 20 closes the electrical circuit.
  • the reluctant magnetic circuit is then created so that the current I, crossing the conductive tracks 31, 32 and the mobile contact 21 effecting the junction, generates a magnetic field B whose field lines encircle the conductive tracks 31, 32 and the movable contact 21.
  • These field lines are formed transversely to the direction of the current 1 passing through the tracks 31, 32 and follow the U-shape of the reinforcement circuit 4, pass through a first gap E 1 , follow the ferromagnetic layer 200 of the membrane 20 and pass by the second gap E 2 before joining the reinforcement circuit 4 ( Figures 1 and 2 ).
  • the meaning of these lines of field is determined by the known rule of the corkscrew or the amp-man.
  • the magnetic field B generates an additional contact force F 'of the movable contact 21 of the membrane 20 against the conductive tracks 31, 32 whose intensity varies as a function of the intensity of the current I passing through the microactuator 2.
  • a threshold current is for example the current of appearance of an electric arc.
  • the additional contact force F ' may make it possible to prevent the opening of the microactuator as long as the current flowing in it is greater than the threshold current.
  • This threshold value is, for example, 0.2 Ampere.
  • the membrane 20 is pressed against the conductive tracks 31, 32 by a main contact force F ( figure 8 ) permanent generated for example by the action of a permanent magnetic field such as the first magnetic field B 0 .
  • the passage of the current I through the microactuator 2 creates an additional positive contact force F ', variable according to the oscillations of the current I.
  • F ORV of opposite direction and intensity equal to the sum of the intensity of the main contact force F and the intensity of the additional contact force F 'when it corresponds at an intensity value of the alternating current lower than the threshold value of the electric arc flash current.
  • Such opening force F OUV can be generated by energizing an electromagnet such as that comprising the excitation coil 6.
  • the excitation coil 6 generates the second magnetic field BS 1 of sufficient intensity to create the opening force F OUV .
  • the additional force that can be obtained with such a reluctant magnetic circuit, for a current of 0.2 A through the microactuator 2 is of the order of one hundred ⁇ N. If the main contact force F is 500 ⁇ N and the additional force F 'of 100 ⁇ N for a current of 0.2A, it will be sufficient to generate an opening force F OUV greater than 500 ⁇ N and less than 600 ⁇ N, by example of 520 ⁇ N to be sure to cause the opening of the microactuator 2 without generating an electric arc ( figure 8 ).
  • the reluctant magnetic circuit B 1 thus passes through the reinforcement circuit 4 and the ferromagnetic layer 200 'so as, as before, to generate an additional contact force F'.
  • the movable contact piece 20 ' can be actuated by various means and in particular by closing means, for example magnetic or electromagnetic type generating the first magnetic field B 0 described above and by means of opening for example of the electromagnetic type such as the excitation coil 6 described above.
  • closing means for example magnetic or electromagnetic type generating the first magnetic field B 0 described above
  • opening for example of the electromagnetic type such as the excitation coil 6 described above.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Micromachines (AREA)
  • Semiconductor Integrated Circuits (AREA)
  • Magnetic Treatment Devices (AREA)

Abstract

The invention relates to a microsystem with an integrated reluctant magnetic circuit which subjects a mobile contact piece (20, 20') to an additional contacting force (F"), in the position with a closed electrical circuit, the intensity of which varies as a function of an alternating current (I) flowing across the electric circuit. According to the invention, the variations in said additional contacting force are used to permit the electric circuit to be opened when the current is below a threshold level. Said threshold level can correspond to the value for the appearance of an electric arc.

Description

La présente invention se rapporte à un microsystème intégrant un circuit magnétique réluctant. Ce circuit magnétique réluctant permet notamment, en créant une force de contact supplémentaire, de pouvoir réaliser une ouverture d'un circuit électrique sans générer d'arc électrique.The present invention relates to a microsystem integrating a reluctant magnetic circuit. This reluctant magnetic circuit makes it possible in particular, by creating an additional contact force, to be able to make an opening of an electric circuit without generating an electric arc.

Dans un appareil électrique interrupteur de courant, il est connu de devoir :

  • éviter à l'ouverture du circuit électrique la naissance d'un arc électrique entre les contacts de l'interrupteur afin de limiter l'usure de ces contacts et ainsi d'augmenter la durée de vie du dispositif. Les phénomènes d'arc électrique sont particulièrement destructeurs dans des dispositifs de petites dimensions.
  • disposer d'une force de contact importante afin de permettre une meilleure tenue aux courants transitoires.
  • éviter les rebonds de l'interrupteur à la fermeture pour ne pas souder les contacts entre eux.
In an electrical switch device, it is known to have to:
  • avoid the opening of the electrical circuit the birth of an electric arc between the contacts of the switch to limit the wear of these contacts and thus increase the service life of the device. Arc phenomena are particularly destructive in small devices.
  • have a large contact force to allow better resistance to transient currents.
  • avoid bouncing of the switch when closing so as not to weld the contacts together.

Le brevet US 4,427,957 décrit un dispositif de commutation comportant un circuit magnétique composé d'une partie mobile constituée d'une lame pivotante et d'une partie fixe. Une bobine est enroulée autour de la partie fixe du circuit magnétique. Un circuit électrique d'alimentation d'une charge comporte notamment une pièce de contact électrique solidaire de la lame pivotante et initialement écartée d'une seconde pièce de contact électrique. La première pièce de contact électrique joue également le rôle de ressort mécanique pour la lame pivotante. Lors du passage d'un courant dans la bobine, le circuit magnétique est magnétisé et génère une première force d'attraction pour attirer la lame pivotante. La lame pivote jusqu'à la connexion entre les deux pièces de contact électrique, provoquant la fermeture du circuit électrique mais également celle du circuit magnétique. Les deux pièces de contact électrique étant agencées pour traverser le circuit magnétique, un flux magnétique apparaît donc dans le circuit magnétique. Ce flux magnétique crée une force de contact supplémentaire entre la lame pivotante et la partie fixe du circuit magnétique. Cette force de contact supplémentaire varie en fonction de l'intensité du courant circulant dans le circuit électrique.The patent US 4,427,957 discloses a switching device comprising a magnetic circuit consisting of a movable part consisting of a pivoting blade and a fixed part. A coil is wound around the fixed part of the magnetic circuit. An electrical circuit for supplying a load comprises in particular an electrical contact piece integral with the pivoting blade and initially spaced apart from a second electrical contact piece. The first electrical contact piece also acts as a mechanical spring for the pivoting blade. Upon passage of a current in the coil, the magnetic circuit is magnetized and generates a first attraction force to attract the pivoting blade. The blade pivots to the connection between the two electrical contact parts, causing the closure of the electrical circuit but also that of the magnetic circuit. Since the two electrical contact pieces are arranged to pass through the magnetic circuit, a magnetic flux appears in the magnetic circuit. This magnetic flux creates an additional contact force between the pivoting blade and the fixed part of the magnetic circuit. This additional contact force varies as a function of the intensity of the current flowing in the electric circuit.

Si le courant alimentant la bobine de commande est coupé, la première force d'attraction est annulée. Seule la force d'attraction supplémentaire maintient la lame en position de fermeture du circuit. Etant donné que l'intensité de cette force suit les oscillations du courant à travers le circuit électrique, elle prend une valeur nulle à un moment donné. Lorsque le courant atteint une valeur inférieure à une valeur seuil, la force magnétique supplémentaire devient inférieure à la force mécanique de rappel exercée par le ressort sur la lame pivotante. Sous l'action de cette force mécanique, la lame pivotante s'écarte de la position de fermeture ce qui ouvre le circuit électrique. La valeur seuil de courant est par exemple proche de zéro ce qui permet de couper le circuit lorsque le courant est faible et ainsi d'éviter la génération d'arc électrique.If the current supplying the control coil is cut off, the first attraction force is canceled. Only the additional force of attraction keeps the blade in the closed position of the circuit. Since the intensity of this force follows the oscillations of the current through the electric circuit, it takes a value of zero to one given moment. When the current reaches a value below a threshold value, the additional magnetic force becomes less than the mechanical force of return exerted by the spring on the pivoting blade. Under the action of this mechanical force, the pivoting blade deviates from the closed position which opens the electrical circuit. The current threshold value is for example close to zero, which makes it possible to cut the circuit when the current is low and thus to avoid the generation of an electric arc.

Dans ce dispositif électromécanique, la maîtrise du niveau de courant au-dessous duquel la lame pivotante s'écarte est très difficile à garantir dans le temps. En effet, le retour de la lame s'effectue lorsqu'il existe un déséquilibre entre la force magnétique supplémentaire engendrée par le courant passant dans le circuit électrique et la force de rappel mécanique exercée par le ressort sur la lame pivotante. Or cette dernière dépend fortement de l'assemblage mécanique des pièces du dispositif et de leur usure dans le temps. On assiste donc souvent à une dérive de la valeur seuil du courant à partir de laquelle la force mécanique prend le pas sur la force magnétique.In this electromechanical device, the control of the current level below which the pivoting blade deviates is very difficult to guarantee over time. Indeed, the return of the blade occurs when there is an imbalance between the additional magnetic force generated by the current flowing in the electrical circuit and the mechanical return force exerted by the spring on the pivoting blade. However, the latter depends heavily on the mechanical assembly of the parts of the device and their wear over time. There is therefore often a drift in the threshold value of the current from which the mechanical force takes precedence over the magnetic force.

En outre, la force de rappel mécanique devant être assez importante pour décoller les contacts, générer une force magnétique du même ordre de grandeur avec un courant circulant dans une spire ne semble pas adapté à des courants seuils de quelques milliampères.In addition, the mechanical restoring force must be large enough to take off the contacts, generate a magnetic force of the same order of magnitude with a current flowing in a turn does not seem suitable for threshold currents of a few milliamperes.

Le but de l'invention est de proposer un microsystème permettant de répondre aux différentes exigences définies ci-dessus, dans lequel la coupure du circuit avec un courant ayant une valeur inférieure à une valeur seuil est fiable et parfaitement stable dans le temps.The object of the invention is to propose a microsystem making it possible to respond to the different requirements defined above, in which the breaking of the circuit with a current having a value lower than a threshold value is reliable and perfectly stable over time.

Ce but est atteint par un microsystème comportant :

  • une pièce de contact mobile comportant une couche en matériau ferromagnétique, montée mobile sur un substrat pour commuter un circuit électrique entre une position ouverte et une position fermée,
  • des moyens de fermeture susceptibles d'appliquer une force de contact principale à la pièce de contact mobile en position fermée,
  • un circuit magnétique réluctant appliquant à la pièce de contact mobile en position fermée une force de contact supplémentaire, dont l'intensité varie en fonction d'un courant alternatif traversant le circuit électrique,
  • des moyens d'ouverture qui, suite à un ordre d'ouverture, appliquent à la pièce de contact mobile une force d'ouverture du circuit électrique, dont l'intensité est égale à la somme de l'intensité de la force de contact principale et de l'intensité de la force de contact supplémentaire lorsque celle-ci correspond à une valeur du courant alternatif inférieure à une valeur seuil,
caractérisé en ce que,
  • les moyens de fermeture sont de type magnétique ou électromagnétique et génèrent un premier champ magnétique créant une composante magnétique dans la couche en matériau ferromagnétique de la pièce de contact mobile pour la maintenir dans la position fermée,
  • les moyens d'ouverture comprennent un électroaimant muni d'une bobine d'excitation apte à être alimentée par un courant temporaire pour produire un second champ magnétique et créer une composante magnétique inverse dans la couche en matériau ferromagnétique de la pièce de contact mobile, d'intensité suffisante pour commander le passage de la pièce de contact mobile de la position fermée à la position ouverte.
This goal is achieved by a microsystem comprising:
  • a movable contact piece having a layer of ferromagnetic material mounted movably on a substrate for switching an electrical circuit between an open position and a closed position,
  • closing means capable of applying a main contact force to the movable contact piece in the closed position,
  • a reluctant magnetic circuit applying to the movable contact piece in the closed position an additional contact force, the intensity of which varies as a function of an alternating current flowing through the electric circuit,
  • opening means which, following an opening command, apply to the movable contact piece an opening force of the electrical circuit, of which the intensity is equal to the sum of the intensity of the main contact force and the intensity of the additional contact force when it corresponds to a value of the alternating current lower than a threshold value,
characterized in that
  • the closing means are of magnetic or electromagnetic type and generate a first magnetic field creating a magnetic component in the layer of ferromagnetic material of the movable contact piece to maintain it in the closed position,
  • the opening means comprise an electromagnet provided with an excitation coil adapted to be supplied with a temporary current to produce a second magnetic field and to create a reverse magnetic component in the ferromagnetic material layer of the movable contact piece; sufficient intensity to control the passage of the movable contact piece from the closed position to the open position.

Lorsque le courant est alternatif, la force de contact supplémentaire générée est proportionnelle au carré de l'intensité du courant traversant le microactionneur. Cette force suit donc des oscillations positives successives.When the current is alternating, the additional contact force generated is proportional to the square of the intensity of the current flowing through the microactuator. This force therefore follows successive positive oscillations.

Les avantages liés à l'intégration d'un circuit magnétique réluctant dans un tel microsystème sont donc :

  • de ne permettre l'ouverture de l'interrupteur que pour un courant traversant celui-ci inférieur à une valeur seuil afin d'éviter la formation d'un arc électrique,
  • d'augmenter la force de contact de l'élément mobile de l'interrupteur lorsque le courant passant à travers celui-ci augmente, ce qui lui permet de mieux supporter les courants transitoires,
  • de diminuer les rebonds à la fermeture de l'interrupteur grâce à la présence de la force de contact supplémentaire générée par le circuit magnétique réluctant.
The advantages of integrating a reluctant magnetic circuit in such a microsystem are therefore:
  • to allow the opening of the switch only for a current flowing therethrough below a threshold value in order to avoid the formation of an electric arc,
  • to increase the contact force of the movable element of the switch when the current passing through it increases, which allows it to better withstand the transient currents,
  • to reduce rebounds when the switch is closed by virtue of the presence of the additional contact force generated by the reluctant magnetic circuit.

Contrairement à l'art antérieur, dans le dispositif selon l'invention, il s'agit d'opposer directement des forces magnétiques entre elles, c'est-à-dire le couple magnétique généré par le champ de la bobine d'excitation contre la force de contact principale générée par le premier champ magnétique et la force de contact supplémentaire générée lors du passage du courant dans le circuit électrique. Il est donc plus aisé d'adapter le niveau du courant seuil car le niveau des forces en jeu est semblable.Unlike the prior art, in the device according to the invention, it is a question of directly opposing magnetic forces between them, that is to say the magnetic torque generated by the field of the excitation coil against the main contact force generated by the first magnetic field and the contact force additional generated during the passage of the current in the electrical circuit. It is therefore easier to adjust the level of the threshold current because the level of forces involved is similar.

En outre, les forces magnétiques générées sont indépendantes des phénomènes d'usure du microsystème et des variations de son procédé d'assemblage.In addition, the magnetic forces generated are independent of the wear phenomena of the microsystem and variations in its assembly process.

Selon l'invention, la pièce de contact mobile est bistable. Le premier champ magnétique est permanent et maintient la membrane dans chacune de ses positions. En revanche, le second champ magnétique créé par la bobine d'excitation n'est que transitoire et n'est activé que pour le basculement de la membrane de l'une de ses positions à l'autre de ses positions.According to the invention, the movable contact piece is bistable. The first magnetic field is permanent and maintains the membrane in each of its positions. On the other hand, the second magnetic field created by the excitation coil is only transient and is only activated for the tilting of the membrane from one of its positions to the other of its positions.

Selon une particularité, le premier champ magnétique est uniforme et orienté perpendiculairement au substrat.According to one feature, the first magnetic field is uniform and oriented perpendicularly to the substrate.

Selon une autre particularité, la bobine d'excitation est de type solénoïde et elle entoure le substrat et la pièce de contact mobile.According to another particularity, the excitation coil is of the solenoid type and it surrounds the substrate and the movable contact piece.

Selon une autre particularité, la valeur seuil correspond à la valeur d'intensité d'apparition d'un arc électrique.According to another particularity, the threshold value corresponds to the value of intensity of appearance of an electric arc.

Selon une autre particularité, la couche ferromagnétique forme avec un circuit ferromagnétique de renfort le circuit magnétique réluctant lors du passage du courant alternatif dans le circuit électrique.According to another feature, the ferromagnetic layer forms with a ferromagnetic reinforcement circuit the magnetic circuit reluctant during the passage of the alternating current in the electric circuit.

Selon une autre particularité, le circuit magnétique de renfort est intégré dans le substrat.According to another feature, the magnetic reinforcement circuit is integrated in the substrate.

Selon une autre particularité, le circuit ferromagnétique de renfort est constitué de deux ailes symétriques jointes par une âme centrale perpendiculaire, définissant une section transversale en forme de U.According to another feature, the ferromagnetic reinforcement circuit consists of two symmetrical wings joined by a perpendicular central core, defining a U-shaped cross section.

Selon une autre particularité, le circuit ferromagnétique de renfort est orienté de manière à, dans son sens longitudinal, être parallèle à la direction suivie par le courant lorsque le circuit électrique est fermé.According to another feature, the ferromagnetic reinforcement circuit is oriented so as, in its longitudinal direction, to be parallel to the direction followed by the current when the electric circuit is closed.

Selon une autre particularité, les ailes du circuit ferromagnétique de renfort comportent deux surfaces définissant chacune un entrefer avec une surface parallèle de la couche ferromagnétique de la pièce de contact mobile située en vis-à-vis.According to another feature, the wings of the ferromagnetic reinforcement circuit comprise two surfaces each defining an air gap with a parallel surface of the ferromagnetic layer of the movable contact piece located vis-a-vis.

Selon l'invention, la pièce de contact mobile est constituée d'une membrane ferromagnétique montée pivotante sur le substrat et portant un contact mobile apte en position fermée à relier électriquement deux pistes conductrices fixes disposées sur le substrat pour la fermeture du circuit électrique.According to the invention, the movable contact piece consists of a ferromagnetic membrane pivotally mounted on the substrate and carrying a movable contact adapted in the closed position to electrically connect two fixed conductive tracks arranged on the substrate for closing the electrical circuit.

D'autres caractéristiques et avantages vont apparaître dans la description détaillée qui suit en se référant à un mode de réalisation donné à titre d'exemple et représenté par les dessins annexés sur lesquels :

  • La figure 1 illustre, schématiquement et en coupe longitudinale, un premier mode de réalisation de l'invention.
  • La figure 2 illustre, schématiquement, en coupe transversale selon A-A sur la figure 1, le premier mode de réalisation de l'invention.
  • La figure 3 illustre schématiquement, pris suivant une coupe transversale identique à celle de la figure 2, un second mode de réalisation de l'invention.
  • La figure 4 représente, en perspective, un microactionneur pouvant être utilisé dans le microsystème selon l'invention.
  • La figure 5 illustre le microactionneur selon l'invention positionné dans l'espace défini à l'intérieur d'une bobine d'excitation de type solénoïde.
  • Les figures 6A à 6C illustrent en vue de côté les différentes étapes mises en oeuvre pour le pivotement de la membrane du microactionneur selon l'invention.
  • Les figures 7A et 7B représentent un microsystème selon l'invention placé entre deux pièces d'entrefer d'un circuit magnétique.
  • La figure 8 représente la courbe de variation de la force de contact générée à l'aide du principe de l'invention.
Other features and advantages will appear in the detailed description which follows with reference to an embodiment given by way of example and represented by the appended drawings in which:
  • The figure 1 illustrates, schematically and in longitudinal section, a first embodiment of the invention.
  • The figure 2 illustrates, schematically, in cross-section along AA on the figure 1 , the first embodiment of the invention.
  • The figure 3 illustrates schematically, taken in a cross section identical to that of the figure 2 , a second embodiment of the invention.
  • The figure 4 represents, in perspective, a microactuator that can be used in the microsystem according to the invention.
  • The figure 5 illustrates the microactuator according to the invention positioned in the defined space inside a solenoid-type excitation coil.
  • The Figures 6A to 6C illustrate in side view the different steps used for the pivoting of the membrane of the microactuator according to the invention.
  • The Figures 7A and 7B represent a microsystem according to the invention placed between two gap parts of a magnetic circuit.
  • The figure 8 represents the curve of variation of the contact force generated using the principle of the invention.

Le principe de l'invention consiste à intégrer dans un appareil électrique interrupteur d'un circuit électrique un circuit magnétique réluctant afin de procurer les avantages précités.The principle of the invention consists in integrating in a switch electrical apparatus of an electrical circuit a reluctant magnetic circuit to provide the aforementioned advantages.

Ainsi, dans un appareil électrique interrupteur comportant typiquement une pièce de contact mobile susceptible de commuter un circuit électrique entre une position ouverte et une position fermée, un circuit magnétique réluctant créé par le passage d'un courant alternatif dans le circuit électrique fermé, permet d'appliquer à la pièce de contact mobile une force de contact ou d'écrasement supplémentaire F'. L'intensité de la force de contact supplémentaire F' varie en fonction de l'intensité du courant alternatif circulant dans le circuit électrique et suit des oscillations positives successives (figure 8). De manière plus précise, l'intensité de cette force de contact supplémentaire F' est proportionnelle au carré du courant 1 traversant l'interrupteur lorsque le circuit magnétique réluctant n'est pas saturé.Thus, in a switch electrical apparatus typically having a movable contact piece capable of switching an electrical circuit between an open position and a closed position, a reluctant magnetic circuit created by the passage of an alternating current in the closed electrical circuit allows applying to the movable contact piece an additional contact or crushing force F '. The intensity of the additional contact force F 'varies as a function of the intensity of the alternating current flowing in the electric circuit and follows successive positive oscillations ( figure 8 ). More specifically, the intensity of this additional contact force F 'is proportional to the square of the current 1 passing through the switch when the reluctant magnetic circuit is not saturated.

L'invention consiste à utiliser les variations de cette force de contact supplémentaire F' pour permettre l'ouverture du circuit électrique lorsque le courant est à une intensité inférieure à une valeur seuil. Cette valeur seuil peut correspondre à l'intensité d'apparition d'un arc électrique. La force de contact supplémentaire F' peut permettre d'empêcher l'ouverture de l'interrupteur tant que le courant circulant dans celui-ci est supérieur au courant seuil. Cette valeur seuil est par exemple de 0,2 Ampère.The invention consists in using the variations of this additional contact force F 'to allow the opening of the electric circuit when the current is at an intensity lower than a threshold value. This threshold value may correspond to the intensity of appearance of an electric arc. The additional contact force F 'may make it possible to prevent the switch from opening as long as the current flowing in it is greater than the threshold current. This threshold value is, for example, 0.2 Ampere.

En position fermée, la pièce de contact mobile est soumise à une force de contact principale F créée par des moyens de fermeture. Comme précisé ci-dessus, le circuit magnétique réluctant généré par le passage du courant alternatif circulant dans l'interrupteur suite à la fermeture du circuit permet d'appliquer à la pièce de contact mobile une force de contact supplémentaire F' variable suivant les oscillations du courant. L'ouverture du circuit électrique peut ainsi être réalisée selon le processus suivant :

  • Selon l'invention, après un ordre d'ouverture, la force de contact principale F est toujours appliquée à la pièce de contact mobile. Dans ce cas, pour provoquer l'ouverture du circuit électrique sans générer d'arc électrique, il faut appliquer à la pièce de contact mobile une force d'ouverture FOUV de direction opposée et d'intensité égale à la somme de l'intensité de la force de contact principale F et de la force de contact supplémentaire F' lorsque celle-ci correspond à une valeur du courant alternatif inférieure à la valeur seuil du courant d'apparition d'arc électrique. En générant une telle force, on est sûr d'obtenir l'ouverture du circuit électrique au-dessous du courant seuil et donc d'éviter l'apparition d'un arc électrique.
In the closed position, the movable contact piece is subjected to a main contact force F created by closing means. As specified above, the reluctant magnetic circuit generated by the passage of the alternating current flowing in the switch following closure of the circuit makes it possible to apply to the movable contact piece an additional contact force F 'which varies according to the oscillations of the current. The opening of the electric circuit can thus be carried out according to the following process:
  • According to the invention, after an order of opening, the main contact force F is always applied to the movable contact piece. In this case, to cause the opening of the electric circuit without generating an electric arc, it is necessary to apply to the movable contact piece an opening force F OUV of opposite direction and intensity equal to the sum of the intensity the main contact force F and the additional contact force F 'when the latter corresponds to a value of the alternating current lower than the threshold value of the electric arc flashing current. By generating such a force, it is safe to obtain the opening of the electric circuit below the threshold current and thus to avoid the appearance of an electric arc.

La force de contact principale F est générée par des moyens de fermeture magnétiques ou électromagnétiques. La force d'ouverture est générée par des moyens d'ouverture électromagnétiques.The main contact force F is generated by magnetic or electromagnetic closure means. The opening force is generated by electromagnetic opening means.

La suite de la description est consacrée à un exemple de mise en oeuvre de l'invention dans un microsystème utilisant un microactionneur magnétique. La description de ce mode de réalisation n'est pas limitative et l'emploi de moyens équivalents pourra être envisagé.The remainder of the description is devoted to an exemplary implementation of the invention in a microsystem using a magnetic microactuator. The description of this embodiment is not limiting and the use of equivalent means may be considered.

Un microsystème pourra être un dispositif comportant au moins un microactionneur pouvant être fabriqué selon des technologies de type MEMS ou des technologies classiques de circuit imprimé en PCB ou kapton.A microsystem may be a device comprising at least one microactuator that can be manufactured using MEMS type technologies or conventional PCB or kapton PCB technologies.

Un microactionneur tel que celui décrit ci-dessous est un micro-interrupteur ou micro-commutateur de courant utilisé dans un micro-contacteur, un micro-relais ou un micro-reed. Dans la suite de la description nous emploierons le terme général "microactionneur" pour faire référence à ces différentes applications.A microactuator such as that described below is a microswitch or microswitch current used in a micro-contactor, a micro-relay or a micro-reed. In the following description we will use the general term "microactuator" to refer to these different applications.

En référence à la figure 4 et de manière connue, un microsystème peut comporter un microactionneur 2 monté sur une surface plane 30 d'un substrat 3 fabriqué dans des matériaux comme le silicium, le verre, des céramiques ou sous forme de circuits imprimés.With reference to the figure 4 and in known manner, a microsystem may comprise a microactuator 2 mounted on a flat surface 30 of a substrate 3 made of materials such as silicon, glass, ceramics or in the form of printed circuits.

De manière connue (voir la demande de brevet n° US 2002/0140533 ), le substrat 3 porte sur sa surface 30, par exemple, au moins deux pistes conductrices planes identiques 31, 32 espacées et destinées à être reliées électriquement afin d'obtenir la fermeture du circuit électrique. Pour cela, le microactionneur 2 magnétique porte au moins un contact 21 mobile apte à effectuer la jonction électrique entre les deux pistes 31, 32 lorsque le microactionneur 2 est activé. Lorsque le circuit électrique est fermé, le courant I suit une direction située dans le plan des pistes conductrices 31, 32. Un tel microactionneur 2 est doté d'une pièce de contact mobile portant le contact 21 mobile et constituée d'une membrane 20 ayant un axe longitudinal (A) reliée par une de ses extrémités à un plot 23 d'ancrage solidaire du substrat 3 par l'intermédiaire de deux bras 22a, 22b de liaison. Le contact 21 mobile est par exemple formé sur la membrane 20 à proximité de l'extrémité libre de la membrane 20 et fait face à la surface 30 du substrat 3. La membrane 20 est par exemple constituée d'une couche 200 (figures 1 et 2) en matériau ferromagnétique présentant sur sa surface située en vis-à-vis du substrat 3 un évidement dans lequel est disposé le contact 21.In a known manner (see patent application no. US 2002/0140533 ), the substrate 3 carries on its surface 30, for example, at least two identical planar conductive tracks 31, 32 spaced apart and intended to be electrically connected in order to obtain the closure of the electrical circuit. For this, the magnetic microactuator 2 carries at least one movable contact 21 capable of effecting the electrical junction between the two tracks 31, 32 when the microactuator 2 is activated. When the electrical circuit is closed, the current I follows a direction located in the plane of the conductive tracks 31, 32. Such a microactuator 2 is provided with a movable contact piece carrying the movable contact 21 and consisting of a membrane 20 having a longitudinal axis (A) connected by one of its ends to an anchor stud 23 secured to the substrate 3 by means of two link arms 22a, 22b. The movable contact 21 is for example formed on the membrane 20 near the free end of the membrane 20 and faces the surface 30 of the substrate 3. The membrane 20 consists for example of a layer 200 ( Figures 1 and 2 ) of ferromagnetic material having on its surface facing the substrate 3 a recess in which is disposed the contact 21.

Le microactionneur 2 décrit dans l'invention peut être réalisé par une technologie de duplication planaire de type MEMS (Micro Electro-Mechanical System). En effet, la réalisation par dépôt de couches successives dans un processus itératif se prête bien à la fabrication de tels objets. Dans ce cas, la membrane 20 ainsi que les bras 22a, 22b sont par exemple issus d'une même couche de matériau ferromagnétique. Cependant, dans une autre configuration, les bras 22a, 22b de liaison et une couche inférieure de la membrane 20 peuvent être issus d'une couche métallique. Une couche d'un matériau ferromagnétique est déposée sur cette couche métallique pour générer la partie supérieure de la membrane 20. Une telle configuration peut permettre d'optimiser les propriétés mécaniques des bras 22a, 22b de liaison en utilisant, pour permettre le pivotement de la membrane 20, un matériau mécaniquement plus adapté que le matériau ferromagnétique. De plus, la couche métallique peut faire office de contact pour la fermeture d'un circuit électrique. Le matériau ferromagnétique est par exemple du type magnétique doux et peut être par exemple un alliage de fer et de nickel (« permalloy » Ni80Fe20).The microactuator 2 described in the invention can be realized by a planar duplication technology of MEMS (Micro Electro-Mechanical System) type. Indeed, the realization by deposition of successive layers in an iterative process lends itself well to the manufacture of such objects. In this case, the membrane 20 as well as the arms 22a, 22b are for example derived from the same layer of ferromagnetic material. However, in another configuration, the connecting arms 22a, 22b and a lower layer of the membrane 20 may be derived from a metal layer. A layer of a ferromagnetic material is deposited on this metal layer to generate the part 20. Such a configuration can make it possible to optimize the mechanical properties of the linking arms 22a, 22b by using, to enable the pivoting of the membrane 20, a material which is mechanically more suitable than the ferromagnetic material. In addition, the metal layer can act as a contact for closing an electrical circuit. The ferromagnetic material is for example of the soft magnetic type and can be for example an alloy of iron and nickel ("permalloy" Ni 80 Fe 20 ).

Par l'intermédiaire de ces deux bras 22a, 22b, la membrane 20 est apte à pivoter par rapport au substrat 3 suivant un axe (P) parallèle à l'axe décrit par les points de contact de la membrane 20 avec les pistes conductrices et perpendiculaire à l'axe longitudinal (A) de la membrane 20. Les bras 22a, 22b de liaison forment une liaison élastique entre la membrane 20 et le plot 23 d'ancrage. Dans une telle configuration, le pivotement de la membrane 20 est donc obtenu par flexion des bras 22a, 22b de liaison.Through these two arms 22a, 22b, the membrane 20 is pivotable relative to the substrate 3 along an axis (P) parallel to the axis described by the contact points of the membrane 20 with the conductive tracks and perpendicular to the longitudinal axis (A) of the membrane 20. The connecting arms 22a, 22b form an elastic connection between the membrane 20 and the anchor stud 23. In such a configuration, the pivoting of the membrane 20 is thus obtained by bending the connecting arms 22a, 22b.

Un électroaimant est apte à piloter par effet magnétique le mouvement de pivotement de la membrane 20 entre au moins deux positions, une position de fermeture du circuit électrique et une position d'ouverture du circuit électrique. Un autre champ magnétique généré par exemple par un aimant permanent ou un électroaimant peut être utilisé pour appliquer une force de contact principale F à la membrane 20 dans sa position de fermeture.An electromagnet is able to drive by magnetic effect the pivoting movement of the membrane 20 between at least two positions, a closed position of the electrical circuit and an open position of the electric circuit. Another magnetic field generated for example by a permanent magnet or an electromagnet can be used to apply a main contact force F to the membrane 20 in its closed position.

Selon l'invention, il est donc possible de faire pivoter la membrane 20 autour de son axe (P) de pivotement en soumettant la membrane 20 à un champ magnétique produit par une bobine d'excitation 6 externe de type solénoïde ou planaire. La membrane 20 est donc apte à prendre deux positions extrêmes distinctes. En référence aux figures 6A à 6C, dans une première position extrême (figure 6C), l'extrémité de la membrane 20 portant le contact 21 est relevée et n'est pas en appui contre les pistes conductrices 31, 32. Le circuit électrique est donc ouvert. Dans sa seconde position extrême (figures 6A et 6B), l'extrémité de la membrane 20 portant le contact 21 est en appui contre les pistes conductrices 31, 32. Dans cette seconde position, le circuit électrique est fermé.According to the invention, it is therefore possible to pivot the membrane 20 about its pivot axis (P) by subjecting the membrane 20 to a magnetic field produced by an external excitation coil 6 solenoid type or planar. The membrane 20 is therefore able to take two distinct extreme positions. With reference to Figures 6A to 6C in a first extreme position ( Figure 6C ), the end of the membrane 20 carrying the contact 21 is raised and does not bear against the conductive tracks 31, 32. The electrical circuit is open. In its second extreme position ( Figures 6A and 6B ), the end of the membrane 20 carrying the contact 21 is in abutment against the conductive tracks 31, 32. In this second position, the electrical circuit is closed.

Selon l'invention, un premier champ magnétique B0 préférentiellement le plus uniforme possible, est appliqué au microactionneur 2. Ce premier champ magnétique B0 présente des lignes de champ perpendiculaires à la surface 30 du substrat 3. Comme représenté sur les figures 6A à 6C, les lignes de champ de ce premier champ magnétique B0 sont dirigées vers la surface 30 du substrat 3. Ce premier champ magnétique B0 peut être généré par un aimant permanent ou par un électroaimant. Un circuit magnétique ayant comme source magnétique un aimant 5 permanent ou une bobine 5' électromagnétique peut être utilisé pour créer ce premier champ magnétique B0. Comme représenté aux figures 7A et 7B, ce circuit magnétique se compose d'un aimant 5 permanent (figure 7A) ou d'une bobine 5' électromagnétique (figure 7B) et de deux pièces 50, 51 d'entrefer disposées parallèlement, de part et d'autre de l'aimant 5 permanent ou de la bobine 5' et entre lesquelles le premier champ magnétique B0 est généré. L'utilisation d'un tel circuit magnétique permet de générer un premier champ magnétique B0 uniforme dans l'entrefer.According to the invention, a first magnetic field B 0 preferably as uniform as possible, is applied to the microactuator 2. This first magnetic field B 0 has field lines perpendicular to the surface 30 of the substrate 3. As shown in FIGS. Figures 6A to 6C , the field lines of this first magnetic field B 0 are directed towards the surface 30 of the substrate 3. This first magnetic field B 0 can be generated by a permanent magnet or an electromagnet. A magnetic circuit having as its magnetic source a permanent magnet or an electromagnetic coil 5 'may be used to create this first magnetic field B 0 . As represented in Figures 7A and 7B this magnetic circuit consists of a permanent magnet ( Figure 7A ) or a 5 'electromagnetic coil ( Figure 7B ) and two air gap pieces 50, 51 arranged parallel to each other on either side of the permanent magnet or the coil 5 'and between which the first magnetic field B 0 is generated. The use of such a magnetic circuit makes it possible to generate a first uniform magnetic field B 0 in the gap.

Un électroaimant comportant une bobine 6 d'excitation externe de type solénoïde comme représentée en figure 5, connectée à une source de courant, entoure le substrat 3 ainsi que le microactionneur 2 supporté par le substrat 3. Le microactionneur 2 est donc placé au centre de la bobine 6 d'excitation, dans le canal central de la bobine 6. Le passage d'un courant dans la bobine 6 d'excitation génère un champ magnétique de direction parallèle au substrat 3 et perpendiculaire à l'axe de pivotement (P) de la membrane pour commander le pivotement de la membrane 20 de l'une de ses positions vers l'autre de ses positions. Le sens du courant traversant la bobine 6 d'excitation décide du pivotement de la membrane 20 vers l'une ou l'autre de ses positions extrêmes. La bobine 6 d'excitation de type solénoïde pourra être fabriquée par des techniques de circuit imprimé ou de bobinage d'un fil de cuivre. Le microsystème peut comporter plusieurs microactionneurs organisés en matrice et soumis à l'influence du premier champ magnétique B0 et à celle du second champ magnétique temporaire créé par la bobine 6 pour commander le basculement des microactionneurs. La matrice est placée au centre de la bobine 6 d'excitation.An electromagnet comprising an external excitation coil 6 of the solenoid type as represented in FIG. figure 5 , connected to a current source, surrounds the substrate 3 and the microactuator 2 supported by the substrate 3. The microactuator 2 is placed in the center of the excitation coil 6, in the central channel of the coil 6. The passage a current in the excitation coil 6 generates a magnetic field direction parallel to the substrate 3 and perpendicular to the axis of pivoting (P) of the membrane to control the pivoting of the membrane 20 of one of its positions towards the other of his positions. The direction of the current flowing through the excitation coil 6 decides the pivoting of the membrane 20 towards one or other of its extreme positions. The solenoid-type excitation coil 6 may be manufactured by printed circuit techniques or by winding a copper wire. The microsystem can comprise several microactuators organized in a matrix and subjected to the influence of the first magnetic field B 0 and that of the second temporary magnetic field created by the coil 6 to control the switching of the microactuators. The matrix is placed in the center of the excitation coil 6.

Le substrat 3 supportant le microactionneur 2 et entouré de la bobine 6 d'excitation solénoïde est placé sous l'effet du premier champ magnétique B0, par exemple dans l'entrefer du circuit magnétique décrit ci-dessus en liaison avec les figures 7A et 7B. Comme représenté en figure 6A, le premier champ magnétique B0 génère initialement une composante magnétique BP0 dans la membrane 20 suivant son axe longitudinal (A). Le couple magnétique résultant du premier champ magnétique B0 et de la composante BP0 générée dans la membrane 20 maintient la membrane 20 dans l'une de ses positions extrêmes, par exemple dans la seconde position extrême (figure 6A). Dans la seconde position, le contact 21 porté par la membrane 20 relie électriquement les deux pistes 31, 32 conductrices et le circuit est fermé. Dans la première position extrême (figure 6C), le contact 21 mobile de la membrane 20 est relevé et écarté des contacts fixes 31, 32. Le circuit électrique est ouvert.The substrate 3 supporting the microactuator 2 and surrounded by the solenoid excitation coil 6 is placed under the effect of the first magnetic field B 0 , for example in the gap of the magnetic circuit described above in connection with the Figures 7A and 7B . As represented in Figure 6A the first magnetic field B 0 initially generates a magnetic component BP 0 in the membrane 20 along its longitudinal axis (A). The magnetic torque resulting from the first magnetic field B 0 and the component BP 0 generated in the membrane 20 holds the membrane 20 in one of its extreme positions, for example in the second extreme position ( Figure 6A ). In the second position, the contact 21 carried by the membrane 20 electrically connects the two tracks 31, 32 and the conductive circuit is closed. In the first extreme position ( Figure 6C ), the movable contact 21 of the membrane 20 is raised and spaced from the fixed contacts 31, 32. The electrical circuit is open.

En considérant que la membrane 20 est initialement dans sa seconde position (figure 6A), le basculement vers la première position se produit de la manière suivante :

  • En référence à la figure 6B, le passage d'un courant, dans un sens défini, dans la bobine 6 d'excitation de type solénoïde entourant le substrat 3, génère un second champ magnétique BS1 dont la direction est parallèle au substrat 3 et perpendiculaire à l'axe (P) de pivotement de la membrane 20, son orientation dépendant du sens du courant délivré dans la bobine 6 d'excitation. Le second champ magnétique BS1 créé par la bobine 6 d'excitation génère une composante magnétique BP1 dans la couche magnétique de la membrane 20. Si le courant est délivré dans un sens approprié, cette nouvelle composante magnétique BP1 s'oppose à la composante BP0 générée dans la couche magnétique de la membrane 20 par le premier champ magnétique B0. Si la composante BP1 générée par la bobine 4 d'excitation est d'intensité supérieure à celle générée par le premier champ magnétique B 0, le couple magnétique résultant du premier champ magnétique B0 et de cette composante BP1 s'inverse et provoque le pivotement de la membrane 20 de sa seconde position (figure 6A) vers sa première position (figure 6C).
  • Une fois le pivotement de la membrane 20 effectué, l'alimentation en courant de la bobine 6 d'excitation n'est plus nécessaire. Selon l'invention, le second champ magnétique BS1 créé par la bobine 6 d'excitation n'est que transitoire et n'est utile que pour faire pivoter la membrane 20 d'une position à l'autre. Comme représenté en figure 6C, la membrane 20 est ensuite maintenue dans sa première position sous l'effet du seul premier champ magnétique B0 créant une nouvelle composante magnétique BP2 dans la membrane 20. Le nouveau couple magnétique créé entre le premier champ magnétique B0 et la composante BP2 générée dans la membrane 20 impose à la membrane 20 de se maintenir dans sa première position (figure 6C).
  • Une fois que la membrane 20 a pivoté dans sa première position, le contact 21 porté par la membrane 20 est écarté des deux pistes conductrices 31, 32 présentes sur le substrat 3. Le circuit électrique est alors ouvert.
  • Pour fermer de nouveau le circuit électrique, la membrane 20 doit de nouveau être pivotée vers sa seconde position. Un courant est délivré dans la bobine 6 d'excitation dans un sens opposé à celui défini ci-dessus. Le champ magnétique créé par la bobine 6 d'excitation est donc orienté dans un sens opposé au champ magnétique précédent BS1. Ce champ magnétique génère une composante magnétique dans la membrane 20 opposée à la composante BP2. Si cette nouvelle composante magnétique est d'intensité supérieure à la composante BP2, le couple magnétique résultant du premier champ magnétique B0 et de cette nouvelle composante magnétique provoque le basculement de la membrane 20 vers sa seconde position.
  • L'intensité du courant à délivrer dans la bobine 4 d'excitation pour faire pivoter la membrane 20 dépend du nombre de spires constituant la bobine 6 d'excitation ainsi que de la densité du champ magnétique le long de la bobine 6 d'excitation.
  • Selon une variante de réalisation de ce premier mode de réalisation, la bobine d'excitation est de type planaire (non représentée). Le champ magnétique créé est donc radial. Le substrat est alors disposé par rapport à la bobine de manière que le champ magnétique radial créé par la bobine soit parallèle à la surface 30 du substrat 3 et perpendiculaire à l'axe (P) de pivotement de la membrane 20. Comme dans la variante de réalisation précédente, la bobine d'excitation est externe au substrat et au microactionneur, c'est-à-dire qu'elle est indépendante de ceux-ci. Le substrat portant le microactionneur est par exemple collé à ladite bobine.
Considering that the membrane 20 is initially in its second position ( Figure 6A ), the switch to the first position occurs as follows:
  • With reference to the Figure 6B the passage of a current, in a defined direction, in the solenoid-type excitation coil 6 surrounding the substrate 3, generates a second magnetic field BS 1 whose direction is parallel to the substrate 3 and perpendicular to the axis ( P) of pivoting of the membrane 20, its orientation depending on the direction of the current delivered in the excitation coil 6. The second magnetic field BS 1 created by the excitation coil 6 generates a magnetic component BP 1 in the magnetic layer of the membrane 20. If the current is delivered in a suitable direction, this new magnetic component BP 1 opposes the BP 0 component generated in the magnetic layer of the membrane 20 by the first magnetic field B 0 . If the component BP 1 generated by the excitation coil 4 is of greater intensity than that generated by the first magnetic field B 0 , the magnetic torque resulting from the first magnetic field B 0 and this component BP 1 is reversed and causes the pivoting of the membrane 20 of its second position ( Figure 6A ) to its first position ( Figure 6C ).
  • Once the pivoting of the diaphragm 20 is effected, the power supply of the excitation coil 6 is no longer necessary. According to the invention, the second magnetic field BS 1 created by the excitation coil 6 is only transient and is only useful for pivoting the membrane 20 from one position to the other. As represented in Figure 6C , the membrane 20 is then maintained in its first position under the effect of the only first magnetic field B 0 creating a new magnetic component BP 2 in the membrane 20. The new magnetic torque created between the first magnetic field B 0 and the BP component 2 generated in the membrane 20 requires the membrane 20 to remain in its first position ( Figure 6C ).
  • Once the membrane 20 has pivoted in its first position, the contact 21 carried by the membrane 20 is spaced from the two conductive tracks 31, 32 present on the substrate 3. The electrical circuit is then open.
  • To close the electrical circuit again, the membrane 20 must again be rotated to its second position. A current is delivered in the excitation coil 6 in a direction opposite to that defined above. The magnetic field created by the excitation coil 6 is therefore oriented in a direction opposite to the previous magnetic field BS 1 . This magnetic field generates a magnetic component in the membrane 20 opposite the BP 2 component. If this new magnetic component is of greater intensity than the component BP 2 , the magnetic torque resulting from the first magnetic field B 0 and this new magnetic component causes the tilting of the membrane 20 to its second position.
  • The intensity of the current to be delivered in the excitation coil 4 for pivoting the membrane 20 depends on the number of turns constituting the excitation coil 6 as well as the density of the magnetic field along the excitation coil 6.
  • According to an alternative embodiment of this first embodiment, the excitation coil is of planar type (not shown). The magnetic field created is therefore radial. The substrate is then arranged relative to the coil so that the radial magnetic field created by the coil is parallel to the surface 30 of the substrate 3 and perpendicular to the axis (P) of pivoting of the membrane 20. As in the variant Previous embodiment, the excitation coil is external to the substrate and the microactuator, that is to say, it is independent of them. The substrate carrying the microactuator is for example glued to said coil.

L'invention dont le principe est illustré sur les figures 1 et 2 consiste à créer un circuit magnétique réluctant en utilisant la couche ferromagnétique 200 de la membrane 20 et en intégrant dans le substrat 3 un circuit de renfort 4 également en matériau ferromagnétique. Le matériau ferromagnétique utilisé pour ce circuit de renfort 4 et pour la couche 200 de la membrane 20 est par exemple du type magnétique doux et peut être un alliage de type FeNi (« permalloy »).The invention, the principle of which is illustrated in Figures 1 and 2 consists in creating a reluctant magnetic circuit by using the ferromagnetic layer 200 of the membrane 20 and by integrating into the substrate 3 a reinforcement circuit 4 also made of ferromagnetic material. The ferromagnetic material used for this reinforcing circuit 4 and for the layer 200 of the membrane 20 is, for example, of the soft magnetic type and may be a FeNi type alloy ("permalloy").

Le circuit de renfort 4 est disposé sous les deux pistes conductrices 31, 32 et s'étend au niveau de l'espace séparant les deux pistes 31, 32 pour agir sur la membrane 20 située au-dessus, à la verticale. Vu de côté, ce circuit de renfort 4 a la forme d'un U (figure 2), et présente donc deux ailes 41, 42 symétriques parallèles jointes par une âme centrale 40 perpendiculaire aux deux ailes 41, 42. L'âme centrale 40 est disposée sous les pistes 31, 32 conductrices et les deux ailes 41, 42 s'étendent perpendiculairement de part et d'autre des deux pistes 31, 32 conductrices. Le circuit de renfort 4 est orienté de manière à, dans son sens longitudinal, être parallèle à la direction suivie par le courant I dans les pistes 31, 32 conductrices lorsque le circuit électrique est fermé. Les ailes 41, 42 du circuit de renfort 4 se terminent chacune par une surface 43 située dans un plan parallèle au plan des pistes 31, 32 conductrices de manière à définir chacune un entrefer E1, E2 avec une surface parallèle de la couche ferromagnétique 200 de la membrane 20 située en vis-à-vis. Les deux pistes 31, 32 conductrices sont légèrement surélevées par rapport aux surfaces 43 des ailes 41, 42 de manière à toujours laisser un entrefer E1, E2 résiduel entre le circuit de renfort et la couche ferromagnétique 200 de la membrane 20 même lorsque le contact 21 de la membrane 20 est plaqué contre les pistes 31, 32 conductrices.The reinforcing circuit 4 is disposed under the two conductive tracks 31, 32 and extends at the space between the two tracks 31, 32 to act on the membrane 20 above, in the vertical. Seen from the side, this reinforcing circuit 4 has the shape of a U ( figure 2 ), and therefore has two symmetrical parallel wings 41, 42 joined by a central core 40 perpendicular to the two wings 41, 42. The central core 40 is disposed under the tracks 31, 32 and the two conductive wings 41, 42 extend. perpendicularly on both sides of the two tracks 31, 32 conductors. The reinforcing circuit 4 is oriented so as, in its longitudinal direction, to be parallel to the direction followed by the current I in the conductive tracks 31, 32 when the electric circuit is closed. The wings 41, 42 of the reinforcement circuit 4 each terminate in a surface 43 situated in a plane parallel to the plane of the conductive tracks 31, 32 so as to define each an air gap E 1 , E 2 with a parallel surface of the ferromagnetic layer. 200 of the membrane 20 located vis-à-vis. The two conductive tracks 31, 32 are slightly raised relative to the surfaces 43 of the wings 41, 42 so as to always leave a gap E 1 , E 2 residual between the reinforcing circuit and the ferromagnetic layer 200 of the membrane 20 even when the contact 21 of the membrane 20 is pressed against the tracks 31, 32 conductors.

L'actionnement de la membrane 20 permet de fermer le circuit électrique. Lors du passage d'un courant I dans le circuit électrique, le circuit magnétique réluctant est alors créé de sorte que le courant I, traversant les pistes 31, 32 conductrices et le contact 21 mobile effectuant la jonction, génère un champ magnétique B dont les lignes de champ encerclent les pistes 31, 32 conductrices et le contact 21 mobile. Ces lignes de champ sont formées transversalement à la direction du courant 1 traversant les pistes 31, 32 et suivent la forme en U du circuit de renfort 4, passent par un premier entrefer E1, suivent la couche ferromagnétique 200 de la membrane 20 et passent par le second entrefer E2 avant de rejoindre le circuit de renfort 4 (figures 1 et 2). Le sens de ces lignes de champ est déterminé par la règle connue du tire-bouchon ou du bonhomme d'ampère.The actuation of the membrane 20 closes the electrical circuit. During the passage of a current I in the electric circuit, the reluctant magnetic circuit is then created so that the current I, crossing the conductive tracks 31, 32 and the mobile contact 21 effecting the junction, generates a magnetic field B whose field lines encircle the conductive tracks 31, 32 and the movable contact 21. These field lines are formed transversely to the direction of the current 1 passing through the tracks 31, 32 and follow the U-shape of the reinforcement circuit 4, pass through a first gap E 1 , follow the ferromagnetic layer 200 of the membrane 20 and pass by the second gap E 2 before joining the reinforcement circuit 4 ( Figures 1 and 2 ). The meaning of these lines of field is determined by the known rule of the corkscrew or the amp-man.

Le champ magnétique B génère une force de contact supplémentaire F' du contact 21 mobile de la membrane 20 contre les pistes 31, 32 conductrices dont l'intensité varie en fonction de l'intensité du courant I traversant le microactionneur 2. Selon l'invention, il est donc possible de provoquer l'ouverture du circuit électrique lorsque celui-ci est parcouru par un courant déterminé par exemple inférieur à un courant seuil. Ce courant seuil est par exemple le courant d'apparition d'un arc électrique. La force de contact supplémentaire F' peut permettre d'empêcher l'ouverture du microactionneur tant que le courant circulant dans celui-ci est supérieur au courant seuil. Cette valeur seuil est par exemple de 0,2 Ampère.The magnetic field B generates an additional contact force F 'of the movable contact 21 of the membrane 20 against the conductive tracks 31, 32 whose intensity varies as a function of the intensity of the current I passing through the microactuator 2. According to the invention it is therefore possible to cause the opening of the electrical circuit when it is traversed by a determined current for example less than a threshold current. This threshold current is for example the current of appearance of an electric arc. The additional contact force F 'may make it possible to prevent the opening of the microactuator as long as the current flowing in it is greater than the threshold current. This threshold value is, for example, 0.2 Ampere.

Dans le cas du processus décrit ci-dessus, la membrane 20 est plaquée contre les pistes 31, 32 conductrices par une force de contact principale F (figure 8) permanente générée par exemple par l'action d'un champ magnétique permanent tel que le premier champ magnétique B0. Le passage du courant I traversant le microactionneur 2 crée une force de contact supplémentaire F' positive, variable suivant les oscillations du courant I. Si l'on souhaite provoquer l'ouverture du circuit électrique sans arc électrique, il suffit donc d'appliquer à la membrane 20 du microactionneur 2 une force FOUV de direction opposée et d'intensité égale à la somme de l'intensité de la force de contact principale F et de l'intensité de la force de contact supplémentaire F' lorsque celle-ci correspond à une valeur d'intensité du courant alternatif inférieure à la valeur seuil du courant d'apparition d'arc électrique. En générant une telle force, on est sûr d'obtenir l'ouverture du circuit électrique au-dessous du courant seuil et donc d'éviter l'apparition d'un arc électrique. Une telle force d'ouverture FOUV peut être générée par la mise sous tension d'un électro-aimant tel que celui comportant la bobine 6 d'excitation. La bobine 6 d'excitation génère le second champ magnétique BS1 d'intensité suffisante pour créer la force d'ouverture FOUV.In the case of the process described above, the membrane 20 is pressed against the conductive tracks 31, 32 by a main contact force F ( figure 8 ) permanent generated for example by the action of a permanent magnetic field such as the first magnetic field B 0 . The passage of the current I through the microactuator 2 creates an additional positive contact force F ', variable according to the oscillations of the current I. If it is desired to cause the opening of the electric circuit without an electric arc, it suffices to apply to the membrane 20 of the microactuator 2 a force F ORV of opposite direction and intensity equal to the sum of the intensity of the main contact force F and the intensity of the additional contact force F 'when it corresponds at an intensity value of the alternating current lower than the threshold value of the electric arc flash current. By generating such a force, it is safe to obtain the opening of the electric circuit below the threshold current and thus to avoid the appearance of an electric arc. Such opening force F OUV can be generated by energizing an electromagnet such as that comprising the excitation coil 6. The excitation coil 6 generates the second magnetic field BS 1 of sufficient intensity to create the opening force F OUV .

Pour un microactionneur 2 qui développe typiquement une force de contact principale F de l'ordre de quelques centaines de µN, la force supplémentaire qui peut être obtenue avec un tel circuit magnétique réluctant, pour un courant de 0,2 A traversant le microactionneur 2, est de l'ordre de la centaine de µN. Si la force de contact principale F est de 500 µN et la force supplémentaire F' de 100 µN pour un courant de 0,2A, il suffira de générer une force d'ouverture FOUV supérieure à 500 µN et inférieure à 600 µN, par exemple de 520 µN pour être sûr de provoquer l'ouverture du microactionneur 2 sans générer d'arc électrique (figure 8).For a microactuator 2 which typically develops a main contact force F of the order of a few hundred μN, the additional force that can be obtained with such a reluctant magnetic circuit, for a current of 0.2 A through the microactuator 2, is of the order of one hundred μN. If the main contact force F is 500 μN and the additional force F 'of 100 μN for a current of 0.2A, it will be sufficient to generate an opening force F OUV greater than 500 μN and less than 600 μN, by example of 520 μN to be sure to cause the opening of the microactuator 2 without generating an electric arc ( figure 8 ).

Selon une variante de réalisation représentée en figure 3, les pistes conductrices 31, 32 et la pièce de contact mobile 20' comportant la couche ferromagnétique 200' et le contact mobile 21', sont placées dans le U formé par le circuit de renfort 4 en matériau ferromagnétique. Les entrefers E3, E4 du circuit magnétique réluctant B1 créé par le passage du courant I dans le circuit électrique fermé, sont réalisés directement entre les faces latérales internes 44 de chacune des ailes 41, 42 du circuit de renfort 4 et des surfaces opposées parallèles de la couche ferromagnétique 200'. Le circuit magnétique réluctant B1 passe donc par le circuit de renfort 4 et par la couche ferromagnétique 200' afin, comme précédemment, de générer une force de contact supplémentaire F'.According to an alternative embodiment represented in figure 3 , the conductive tracks 31, 32 and the movable contact piece 20 'comprising the ferromagnetic layer 200' and the movable contact 21 'are placed in the U formed by the reinforcing circuit 4 made of ferromagnetic material. The air gaps E 3 , E 4 of the reluctant magnetic circuit B 1 created by the passage of the current I in the closed electrical circuit, are made directly between the inner lateral faces 44 of each of the wings 41, 42 of the reinforcement circuit 4 and the surfaces parallel opposites of the ferromagnetic layer 200 '. The reluctant magnetic circuit B 1 thus passes through the reinforcement circuit 4 and the ferromagnetic layer 200 'so as, as before, to generate an additional contact force F'.

Dans une telle variante de réalisation, la pièce de contact mobile 20' peut être actionnée par différents moyens et notamment par des moyens de fermeture par exemple de type magnétique ou électromagnétique générant le premier champ magnétique B0 décrit ci-dessus et par des moyens d'ouverture par exemple de type électromagnétique telle que la bobine 6 d'excitation décrite ci-dessus. Le fonctionnement de cette variante est identique à celui décrit précédemment.In such an alternative embodiment, the movable contact piece 20 'can be actuated by various means and in particular by closing means, for example magnetic or electromagnetic type generating the first magnetic field B 0 described above and by means of opening for example of the electromagnetic type such as the excitation coil 6 described above. The operation of this variant is identical to that described above.

Il est bien entendu que l'on peut, sans sortir du cadre de l'invention, imaginer d'autres variantes et perfectionnements de détail et de même envisager l'emploi de moyens équivalents.It is understood that one can, without departing from the scope of the invention, imagine other variants and refinements of detail and even consider the use of equivalent means.

Claims (10)

  1. Microsystem comprising:
    - a movable contact part (20, 20') comprising a layer (200, 200') of ferromagnetic material, mounted movably on a substrate (3) so as to switch an electrical circuit between an open position and a closed position,
    - closing means able to apply a main contact force (F) to the movable contact part in the closed position,
    - a reluctant magnetic circuit applying to the movable contact part in the closed position an additional contact force (F'), whose intensity varies as a function of an AC current (I) passing through the electrical circuit,
    - opening means which, following an open order, apply an opening force (FOPN) to the movable contact part to open the electrical circuit, whose intensity is equal to the sum of the intensity of the main contact force (F) and of the intensity of the additional contact force (F') when the latter corresponds to a value of the AC current below a threshold value,
    characterized in that,
    - the closing means are of magnetic or electromagnetic type and generate a first magnetic field (B0) creating a magnetic component (BP0) in the layer (200, 200') of ferromagnetic material of the movable contact part (20, 20') so as to maintain it in the closed position,
    - the opening means comprise an electromagnet furnished with an excitation coil (6) able to be energized by a temporary current so as to produce a second magnetic field (BS1) and create an inverse magnetic component (BP1) in the ferromagnetic material layer (200, 200') of the movable contact part (20, 20'), of sufficient intensity to cause the movable contact part to pass from the closed position to the open position.
  2. Microsystem according to Claim 1, characterized in that the first magnetic field (B0) is uniform and oriented perpendicularly to the substrate (3).
  3. Microsystem according to Claim 1 or 2, characterized in that the excitation coil (6) is of solenoid type and in that it surrounds the substrate (3) and the movable contact part.
  4. Microsystem according to one of Claims 1 to 3, characterized in that the threshold value corresponds to the intensity value upon the appearance of an electric arc.
  5. Microsystem according to one of Claims 1 to 4, characterized in that the ferromagnetic layer (200, 200') forms with a ferromagnetic strengthening circuit (4) the reluctant magnetic circuit when the AC current (I) flows through the electrical circuit.
  6. Microsystem according to Claim 5, characterized in that the magnetic strengthening circuit (4) is integrated into the substrate (3).
  7. Microsystem according to Claim 5 or 6, characterized in that the ferromagnetic strengthening circuit (4) consists of two symmetric wings (41, 42) joined by a perpendicular central web (40), defining a U-shaped transverse section.
  8. Microsystem according to one of Claims 5 to 7, characterized in that the ferromagnetic strengthening circuit (4) is oriented in such a way as, in its longitudinal sense, to be parallel to the direction followed by the current (I) when the electrical circuit is closed.
  9. Microsystem according to Claim 7 or 8, characterized in that the wings (41, 42) of the ferromagnetic strengthening circuit (4) comprise two surfaces (43, 44) each defining a gap (E1, E2, E3, E4) with a parallel surface of the ferromagnetic layer (200, 200') of the movable contact part (20, 20') situated opposite.
  10. Microsystem according to one of Claims 1 to 9, characterized in that the movable contact part consists of a ferromagnetic membrane (20, 20') mounted pivotably on the substrate (3) and bearing a movable contact (21, 21') able in the closed position to electrically link two fixed conducting tracks (31, 32) disposed on the substrate (3) for the closing of the electrical circuit.
EP06707675A 2005-01-10 2006-01-06 Microsystem with integrated reluctant magnetic circuit Not-in-force EP1836713B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
FR0550085A FR2880729B1 (en) 2005-01-10 2005-01-10 MICROSYSTEM WITH ELECTROMAGNETIC CONTROL
FR0550666A FR2883274B1 (en) 2005-03-15 2005-03-15 MICROSYSTEM INTEGRATING A RELUCTANT MAGNETIC CIRCUIT
PCT/EP2006/050075 WO2006072628A1 (en) 2005-01-10 2006-01-06 Microsystem with integrated reluctant magnetic circuit

Publications (2)

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EP1836713A1 EP1836713A1 (en) 2007-09-26
EP1836713B1 true EP1836713B1 (en) 2010-03-03

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EP06707675A Not-in-force EP1836713B1 (en) 2005-01-10 2006-01-06 Microsystem with integrated reluctant magnetic circuit

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EP (1) EP1836713B1 (en)
AT (1) ATE459970T1 (en)
DE (1) DE602006012619D1 (en)
WO (1) WO2006072628A1 (en)

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS57119419A (en) * 1981-01-16 1982-07-24 Omron Tateisi Electronics Co Switching device
DE3233686A1 (en) * 1982-09-10 1984-03-15 Ranco Inc., 43201 Columbus, Ohio SNAP CONTACT SWITCH FOR AC
US5070317A (en) * 1989-01-17 1991-12-03 Bhagat Jayant K Miniature inductor for integrated circuits and devices
US6469602B2 (en) * 1999-09-23 2002-10-22 Arizona State University Electronically switching latching micro-magnetic relay and method of operating same
US20030025580A1 (en) * 2001-05-18 2003-02-06 Microlab, Inc. Apparatus utilizing latching micromagnetic switches
WO2004027799A2 (en) * 2002-09-18 2004-04-01 Magfusion, Inc. Method of assembling a laminated electro-mechanical structure

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EP1836713A1 (en) 2007-09-26
DE602006012619D1 (en) 2010-04-15
ATE459970T1 (en) 2010-03-15

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