EP1901325A1 - Switching device including magnetic microswitches organized in a matrix - Google Patents

Abstract

The device has a matrix of magnetic dip switches each with a ferromagnetic membrane (20) integrated to a substrate, and positioned near intersections formed by electrical tracks. Arms and anchoring studs are integrated in perimeter of the membrane. The membrane is maintained in a stable manner in two positions by an effect of permanent magnetic field commonly generated at the switches. Passage of control electric current (I1, I2) in two of the tracks (Ci, Lj) along a preset direction controls position change of the membrane of the switch located at the intersection of the two tracks.

Description

The present invention relates to a switching device composed of a matrix of magnetic microswitches. The invention relates more particularly to a principle of addressing a microswitch within the matrix.

It is known from the patent US 6,469,602 magnetic microswitches comprising a ferromagnetic material beam controlled between an open position and a closed position for switching an electrical circuit. The ferromagnetic beam is sensitive to magnetic fields. A first magnetic field generated for example by a permanent magnet induces a magnetization along the longitudinal axis of the beam, keeping the beam in a first position. Under the effect of a transient magnetic field generated by the passage of a temporary current through a conductor, the beam switches to a second position by reversing the magnetic torque. The beam is then maintained in this second position under the sole effect of the permanent magnetic field generated by the magnet. In this prior art, the conductor is a planar coil integrated in the substrate.

These microswitches are often organized in matrix so as to form a switching device in which each microswitch can be controlled separately through the planar coil associated therewith. However, the multiplication of the number of coils on the substrate of the matrix requires a large substrate surface which therefore limits the possibilities of miniaturization of the device.

It was proposed by the documents EP 1 241 697 and EP 1 331 656 individually controlling each microswitch of a matrix of microswitches using a network of interwoven conductive lines. A microswitch is placed at each intersection of a line and a column and can be controlled individually by sending a current in the two conductive lines corresponding to this line and this column. However, the micro-switches used in the matrix are particularly bulky because they comprise a magnetic circuit provided with portions passing through the substrate and placed under the substrate. In addition, to function, the microswitches each require the use of a particular magnet disposed under the substrate to bias the magnetic circuit.

The object of the invention is to propose a switching device comprising magnetic micro-switches organized in matrix, which can be controlled separately without occupying a substantial space on the substrate, under the substrate and through the substrate.

• l'élément mobile de tous les micro-interrupteurs est apte à être maintenu de manière stable dans chacune de ses deux positions sous le seul effet d'un champ magnétique permanent généré de manière commune à tous les micro-interrupteurs,
• le passage d'un courant électrique de commande selon un sens déterminé, dans deux lignes conductrices commande le changement de position de l'élément mobile du micro-interrupteur magnétique situé à l'intersection des deux lignes conductrices.

This object is achieved by an electrical switching device comprising a plurality of magnetic microswitches arranged in a matrix on a substrate and each comprising a movable element controlled between two positions and mounted on a surface of the substrate, the device comprising a network of conductive lines. intersecting, the magnetic microswitches being positioned near intersections formed by the conductive lines, the device being characterized in that:

• the movable element of all the microswitches is able to be held stably in each of its two positions under the sole effect of a permanent magnetic field generated in common with all the microswitches,
• the passage of an electric control current in a specific direction, in two conductive lines controls the change of position of the movable element of the magnetic microswitch located at the intersection of the two conductive lines.

According to a feature, the conductive lines are electrical tracks made in the substrate.

According to another feature, the network consists of a first series of rectilinear and parallel electrical tracks formed in a first plane and oriented in a first direction and a second series of parallel electrical tracks formed in a second plane parallel to the foreground and oriented in a second direction.

According to another feature, the second direction is for example orthogonal to the first direction.

According to another feature, the movable element of each microswitch consists of a ferromagnetic membrane having a longitudinal axis along which the magnetic field induces a magnetic component. The longitudinal axis of the membrane of each microswitch is oriented along the bisector of the angle formed between the two conductive lines which intersect under the membrane. If the conductive lines are orthogonal to each other, the longitudinal axis of each microswitch will therefore be oriented at 45 ° with respect to the two conductive lines which intersect under their membrane.

According to another feature, the membrane of each microswitch has an axis of rotation perpendicular to its longitudinal axis, in which it is adapted to pivot between its two positions by reversing the magnetic torque.

According to another feature, the ferromagnetic membrane has two torsion arms anchored on the substrate and inscribed in the membrane. This characteristic contributes to make the matrix particularly compact since the torsion arms no longer project outwardly.

According to another feature, the device comprises an electronic control device associated with the matrix for controlling the injection of current into the appropriate conductive lines of the network as a function of the microswitch to be addressed.

• La figure 1 représente en perspective un micro-interrupteur magnétique.
• La figure 2 représente en vue de dessus le micro-interrupteur magnétique de la figure 1, auquel est adjoint une bobine de commande du micro-interrupteur.
• La figure 3 représente un dispositif de commutation composé d'une matrice de micro-interrupteurs magnétiques du type de celui représenté en figure 2.
• Les figures 4 et 5 illustrent schématiquement, selon l'invention, le principe d'adressage d'un micro-interrupteur magnétique.
• Les figures 6, 7 et 8 illustrent le principe de fonctionnement d'un micro-interrupteur magnétique.
• La figure 9 représente un dispositif de commutation composé d'une matrice de micro-interrupteurs adressés chacun selon le principe détaillé en figures 4 et 5.
• La figure 10 représente en vue de dessus une variante de réalisation avantageuse d'un micro-interrupteur magnétique.

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:

• Figure 1 shows in perspective a magnetic microswitch.
• FIG. 2 represents a view from above of the magnetic microswitch of FIG. 1, to which is added a control coil of the microswitch.
• FIG. 3 represents a switching device composed of a matrix of magnetic microswitches of the type of that represented in FIG. 2.
• Figures 4 and 5 illustrate schematically, according to the invention, the addressing principle of a magnetic microswitch.
• Figures 6, 7 and 8 illustrate the operating principle of a magnetic microswitch.
• FIG. 9 represents a switching device composed of a matrix of micro-switches, each addressed according to the principle detailed in FIGS. 4 and 5.
• FIG. 10 is a top view of an advantageous variant embodiment of a magnetic microswitch.

A magnetic microswitch 2 as shown in FIG. 1 comprises a bistable mobile element mounted on 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 at least two contacts or conductive tracks 31, 32 plane, identical and spaced, intended to be electrically connected by a movable electrical contact 21 to obtain the closure of an electrical circuit (not shown) .

The movable element is composed of a deformable membrane 20 having at least one layer of ferromagnetic material. The membrane has a longitudinal axis (A) and is integral with the substrate 3 by means of two linking arms 22a, 22b connecting said membrane 20 to two anchoring studs 23a, 23b arranged symmetrically on both sides of its longitudinal axis (A). By twisting the two connecting arms 22a, 22b, the membrane 20 is able to pivot between an open position and a closed position along an axis of rotation (R) parallel to the axis described by the contact points of the membrane 20 with the electric tracks 31, 32 and perpendicular to its longitudinal axis (A). The movable electrical contact 21 is disposed under the membrane 20, at the distal end thereof relative to its axis (R) of rotation.

When the membrane is in the closed position, the movable contact 21 electrically connects the two fixed conductive tracks 31, 32 disposed on the substrate, to close the electrical circuit. When the membrane is in the open position, the movable contact 21 is moved away from the two conductive tracks so as to open the electric circuit.

Such a microswitch 2 can be realized by a planar duplication technology of the MEMS type (for "Micro Electro-Mechanical System"). The membrane 20 and the connecting arms 22a, 22b are for example derived from the same layer of ferromagnetic material. 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 ).

With reference to FIG. 10, in order to gain space on the surface of the substrate, the torsion arms 22a, 22b and the anchoring studs 23a, 23b are inscribed in the perimeter of the membrane 20. Twist 22a, 22b therefore no longer extend outwardly of the membrane 20 but inwardly. They are inscribed in the membrane 20 and join the anchoring studs 23a, 23b located directly under the membrane 20.

The integration of the anchoring studs 23a, 23b and torsion arms 22a, 22b in the perimeter of the membrane 20 has the advantage of reducing the bulk of the component and therefore its manufacturing cost (by reducing the substrate surface necessary and increasing yields).

The magnetic actuation of a microswitch 2 as represented in FIG. 1 or 10 consists of subjecting the membrane 20 to a permanent magnetic field B ₀ , preferably uniform and for example of direction perpendicular to the surface of the substrate 3 to maintain the membrane 20 in each of its positions, and to apply a temporary control magnetic field to control the passage of the membrane 20 from one position to another, by inverting the magnetic torque exerted on the membrane.

To generate the permanent magnetic field B ₀ , a permanent magnet (not shown) is used, for example fixed under the substrate 3. In the prior art, the Temporary magnetic field is generated using a planar excitation coil 4 associated with microswitch 2 (Figure 2). The passage of a current in the planar excitation coil 4 generates a temporary magnetic field direction parallel to the substrate 3 and parallel to the longitudinal axis (A) of the membrane 20 to control, in the direction of the current in the coil , the tilting of the membrane 20 from one of its positions to the other of its positions.

According to the invention, the use of planar excitation coils for separately controlling a plurality of microswitches distributed on a matrix as shown in FIG. 3 considerably increases the surface area of the substrate accommodating the microswitches.

According to the invention, the planar coil 4 associated with a microswitch 2 is thus replaced by two superposed rectilinear conductive lines electrically insulated from one another and forming an intersection between them (FIG. 4). The two conductive lines are for example electric tracks Ci, Lj formed in the substrate 3 and for example orthogonal to each other.

According to the invention, with reference to FIGS. 4 and 5, the membrane 20 of the microswitch is positioned on the substrate 3 at the intersection of the two tracks Ci, Lj. The longitudinal axis (A) of the membrane 20 is oriented along the bisector of the angle formed between the two tracks Ci, Lj. In Figures 4 and 5, the two tracks Ci, Lj being orthogonal to each other, the longitudinal axis (A) of the membrane 20 is oriented at 45 ° with respect to each of the two tracks Ci, Lj (Figure 5). In addition, the axis of rotation (R) of the microswitch 2 is located in a parallel plane greater than the planes of the electrical tracks.

To control the membrane 20 of the microswitch 2, a control current I ₁ , I ₂ for example of identical amplitude is injected into each of the two tracks Ci, Lj. The direction of passage of the control current I ₁ , I ₂ in the tracks fixes the direction of rotation of the diaphragm 20. The control current I ₁ , I ₂ injected into each track Ci, Lj generates respectively a magnetic field B ₁ and B ₂ running perpendicularly around the track (Figure 4). At the intersection of the two tracks Ci, Lj, the superposition of the two magnetic fields B ₁ , B ₂ generates a resulting magnetic field Br oriented at 45 ° with respect to the tracks as represented in FIG. 5. This resulting magnetic field Br induces a component Magnetic BP ₃ in the membrane 20 of sufficient intensity to control the tilting of the membrane 20 to its other position (Figure 7). The principle of actuation of a magnetic microswitch is detailed below:

The substrate 3 supporting the membrane 20 is placed under the effect of the permanent magnetic field B ₀ already defined above. As shown in Figure 6, the first magnetic field B ₀ initially generates a magnetic component BP ₂ in the membrane 20 along its longitudinal axis (A). The magnetic torque resulting from the first magnetic field B ₀ and the BP component ₂ generated in the membrane 20 holds the membrane 20 in one of its positions, for example the closed position in FIG. 6.

With reference to FIG. 7, the passage of a control current I ₁ , I ₂ in a defined direction in each of the two electrical tracks Ci, Lj crossing under the membrane 20 makes it possible to generate the resulting magnetic field Br defined ci above whose direction is parallel to the substrate 3 and oriented at 45 ° with respect to the two tracks Ci, Lj, its direction depending on the direction of the current I ₁ , I ₂ delivered in each of the tracks Ci, Lj. The resulting magnetic field Br generates the magnetic component BP ₃ in the magnetic layer of the membrane 20. If the control current I ₁ , I ₂ is delivered in each track Ci, Lj in a suitable direction, this new magnetic component BP ₃ s is opposed to the component BP ₂ generated in the magnetic layer of the membrane 20 by the first magnetic field B ₀ . If the BP component ₃ 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 BP ₃ component is reversed and causes the membrane 20 to tilt. closing position to its open position (Figure 7).

Once the diaphragm has been tilted, the current supply of the two tracks Ci, Lj is no longer necessary. According to the invention, the resulting magnetic field Br is generated only transiently to tilt the membrane 20 from one position to another. As represented in FIG. 8, the membrane 20 is then kept in its open position under the effect of the only first magnetic field B ₀ creating a new magnetic component BP ₄ in the membrane 20 and a new magnetic torque imposing on the membrane 20 to stay in its open position (Figure 6).

According to the invention, the passage of an electric current I ₁ , I ₂ in two conductive lines Ci, Lj thus controls, by inversion of the magnetic torque applying to the membrane 20, the change of position of the membrane 20 of the microphone magnetic switch located at the intersection of the two conductive lines Ci, Lj.

In a matrix of magnetic microswitches, this control and actuation principle can be used to individually address each magnetic microswitch within the matrix. The permanent magnetic field B ₀ is for example common to all microswitches 2 of the matrix.

For this, with reference to FIG. 9, a network of electrically insulated electrical tracks is constructed between them under the matrix of microswitches 2. The network consists of a first series of electrical tracks (C1, C2, C3, C4 , C5, C6) rectilinear and parallel formed in a first plane and oriented in a first direction and a second series of parallel electrical tracks (L1, L2, L3, L4, L5, L6) formed in a second plane parallel to the first plane and oriented in a direction orthogonal to the first direction. The first series of electrical tracks (C1-C6) is for example organized in columns and the second series of electric tracks (L1-L6) is organized in lines (Figure 9).

Magnetic microswitches 2 as defined above and shown in Figure 1 or 10 are positioned near each intersection of two electrical tracks from the first series and the second series. The membranes 20 of each microswitch 2 are all oriented at 45 ° as defined above. The axis of rotation (R) of each microswitch 2 is located in a parallel plane greater than the two planes containing the electrical tracks C1-C6, L1-L6 of the network.

To address a microswitch 2 in the matrix thus formed, a control current of equal amplitude, for example, is injected into the two tracks which intersect under the membrane 20 to be tilted. Depending on the direction of passage of the current in each of the two tracks, the membrane will switch in one or the other of its positions according to the principle described above. The use of such a network therefore makes it easy to address each microswitch 2 identified for example by coordinates within the network. These coordinates are the references of the electrical tracks intersecting under the membrane of the microswitch 2 controlled. By injecting a control current I ₁ , I ₂ at a time in the tracks C3 and L2 of FIG. 9, the membrane 20 of the microswitch 2 located at the intersection of these two tracks is tilt-controlled according to the principle of actuation described above in connection with Figures 4 to 8.

According to the invention, the amplitude of the resulting field Br makes it possible to switch the membrane of the addressed microswitch. On the other hand, the magnetic fields B1, B2 generated around the tracks by the injection of the control current I1, I2 are insufficient to control the tilting of the membranes of the other microswitches located on the network.

An electronic control device (not shown) will for example be associated with the matrix for controlling the injection of a control current into the appropriate electrical tracks of the network according to the microswitch or 2 to be addressed.

Claims (9)

An electrical switching device comprising a plurality of matrix-structured micro-switches (2) on a substrate (3) and each comprising a movable element (20) controlled between two positions and mounted on a surface of the substrate, the device comprising a network conductive lines (C1-C6, L1-L6) intersecting, the microswitches (2) being positioned near magnetic intersections formed by the conductive lines (C1-C6, L1-L6), the device being characterized in that that : the movable element is able to be held stably in each of its two positions under the sole effect of a permanent magnetic field (B ₀ ) generated in common with all the microswitches (2), - The passage of an electric control current (I ₁ , I ₂ ), in a given direction, in two conductive lines (Ci, Lj) controls the change of position of the movable member (20) of the magnetic microswitch. located at the intersection of the two conductive lines (Ci, Lj). Device according to claim 1, characterized in that the conductive lines are electrical tracks made in the substrate (3). Device according to Claim 2, characterized in that the network consists of a first series of rectilinear and parallel electrical tracks (C1-C6) formed in a first plane and oriented in a first direction and a second series of electrical tracks. (L1, L6) formed parallel in a second plane parallel to the foreground and oriented in a second direction. Device according to claim 3, characterized in that the second direction is orthogonal to the first direction. Device according to one of claims 1 to 4, characterized in that the movable element of each microswitch (2) consists of a ferromagnetic membrane (20) having a longitudinal axis (A) in which the magnetic field ( B ₀ ) induces a magnetic component (BP ₂ , BP ₄ ). Device according to claim 5, characterized in that the longitudinal axis (A) of the diaphragm (20) of each microswitch (2) is oriented according to the bisector of the angle formed between the two conductive lines (Ci, Lj) which intersect under the membrane (20). Device according to claim 5 or 6, characterized in that the membrane (20) of each micro-switch (2) has an axis of rotation (R) perpendicular to its longitudinal axis (A), in which it is able to pivot between its two positions by reversing the magnetic torque. Device according to one of claims 5 to 7, characterized in that the ferromagnetic membrane (20) has two torsion arms (22a, 22b) anchored on the substrate (3) and inscribed in the membrane (20). Device according to one of Claims 1 to 8, characterized in that it comprises an electronic control device associated with the matrix for controlling the injection of current into the appropriate conducting lines of the network as a function of the microswitch (2). to address.

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