Classifications

• • 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
  • H01H1/00—Contacts
  • H01H1/0036—Switches making use of microelectromechanical systems [MEMS]
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H36/00—Switches actuated by change of magnetic field or of electric field, e.g. by change of relative position of magnet and switch, by shielding
  • H01H2036/0093—Micromechanical switches actuated by a change of the magnetic field
• • 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 comprising at least one magnetic microactuator actuated by means of an external excitation coil.
• Such a microsystem can be used as electrical switch device, in particular of the switch, contactor or relay type.
• This type of microsystem is particularly adapted to be realized by MEMS technology.
• US 6,320,145 discloses a magnetostatic relay. This relay operates using a monostable and magnetisable beam. Under the action of a magnetic field, this beam bends to tend to align in the direction of this magnetic field and closes an electrical circuit. The beam being made of an elastic material, it returns to its initial position simply by mechanical effect when the interaction of the magnetic field with the beam is zero. The restoring force of the beam towards its initial position is therefore of purely mechanical origin and is imposed solely by the nature of the material of manufacture of the beam and by the geometry of the elements involved.
• US Pat. Nos. 6,469,602 and 6,750,745 describe magnetic micro-relays using the movement, between two positions, of a bistable magnetizable beam to control the opening or closing of an electrical circuit.
• the movement of the beam is controlled by an electromagnet.
• the electric circuit In a first position of the beam, the electric circuit is open and in a second position of the beam, the electric circuit is closed. Closing of the electrical circuit is ensured when the beam is in its second position by contacting contacts carried by the beam with fixed contacts arranged on a substrate.
• the beam At rest, the beam is in its first position and the electric circuit is open. This rest position is maintained thanks to the magnetic field produced on the magnetizable beam by a permanent magnet.
• planar coil integrated in the substrate increases the average surface area of the substrate required by microactuator, which entails an additional cost for each microactuator,
• the integration of the coil into the substrate adds steps to the planar manufacturing process which reduces the production yield and entails an additional cost for each microactuator
• the object of the invention is therefore to provide a microsystem for overcoming the aforementioned drawbacks, which is of a simple design, a moderate cost and which may include, if necessary, a large number of microactuators.
• a magnetic microactuator comprising a mobile element supported by a substrate and controlled by a magnetic effect between a first position and a second position for switching at least one electrical circuit
• an excitation coil external to the substrate, said excitation coil being able, when energized, to subjecting the movable member to a second magnetic field to move the movable member from the first position to the second position, characterized in that, the excitation coil is of the solenoid type and in that it surrounds the substrate supporting the mobile element.
• the microactuator is thus placed in the center of the solenoid coil.
• the coil is external to the substrate, that is to say not integrated therewith, which makes it possible to overcome some of the disadvantages listed above.
• the manufacture of an external coil by printed circuit techniques, by winding copper wire or any other three-dimensional packaging solution does not have the disadvantages of an integrated coil and the yields for these techniques are very well controlled.
• the movable element comprises a membrane mounted on the substrate, having a longitudinal axis and able to pivot between its different positions along an axis perpendicular to the longitudinal axis, said membrane having at least one layer made of a magnetic material .
• the magnetic field is generated using a permanent magnet, for example glued on the substrate.
• one step is to properly position the permanent magnet relative to the microactuator so that the magnetic field generated by the magnet has the desired influence on the movable member of the microactuator.
• the use of an air gap in which the first magnetic field generated is uniform makes it possible to dispense with this step during assembly.
• the first magnetic field created in the air gap is uniform and is oriented perpendicular to the surface of the substrate supporting the microactuator.
• This first magnetic field generates in the membrane a magnetic component along its axis.
• the magnetic torque resulting from this field and the magnetic component in the membrane forces the latter to remain in a position.
• the second magnetic field created by the excitation coil is perpendicular to the direction of the first magnetic field.
• This second field generates a magnetic component in the membrane along its axis which opposes the first component generated by the magnetic field. If this new magnetic component is of greater amplitude, the membrane pivots to its other position.
• the solenoid-type excitation coil has a variable coil density along its length.
• the excitation coil comprises a greater number of turns at each of its ends. This makes it possible to standardize the second axial magnetic field generated in the solenoid and thus to increase the useful volume of the solenoid.
• the magnetic source of the magnetic circuit for generating the first magnetic field is a permanent magnet or an electromagnetic coil.
• the substrate is subjected to a uniform magnetic field whose field lines follow a direction not perpendicular to the plane defined by the surface of the substrate supporting the magnetic microactuator.
• a uniform magnetic field whose field lines follow a direction not perpendicular to the plane defined by the surface of the substrate supporting the magnetic microactuator.
• MEMS Micro Electro-Mechanical System
• the inclination of the microactuator membrane is guaranteed by the arrangement of the microsystem in the magnetic circuit generating the uniform field and not by the thickness of the sacrificial layer.
• the sacrificial layer located between the membrane and the substrate can therefore be thin.
• the microsystem can control the opening and closing of two electrical circuits.
• the microsystem can be manufactured at least partly according to a MEMS type technology.
• the substrate supports a plurality of identical magnetic microactuators able to be controlled simultaneously by said excitation coil.
• a solenoid-type excitation coil surrounding the substrate therefore acts on a matrix of microactuators.
• the matrix is placed in the center of the solenoid coil.
• the microactuators are for example micro-relays connected by electrical tracks and arranged in series to increase the insulation voltage or in parallel to divide the intensity of the current.
• FIG. 1 represents, in perspective, a microsystem according to a particular embodiment of the invention.
• FIGS. 2A and 2B show, in perspective, a microactuator according to two alternative embodiments that can be used in a microsystem according to the invention.
• FIG. 3A to 3C show, in side view, the various steps implemented for the pivoting of the movable member of a microactuator.
• FIGS. 4A and 4B show a microsystem according to the invention placed between two gap pieces of a magnetic circuit.
• Figures 5A and 5B show two embodiments for improving the contact force of the microactuator.
• FIG. 6 schematically represents an example of winding of turns that can be used for the solenoid coil of a microsystem according to the invention.
• FIG. 7 represents the implementation of a microsystem according to the invention for controlling two electric circuits.
• a microsystem according to the invention controls the opening or closing of an electrical circuit by using a microactuator 2, 2 "magnetic.
• a microsystem comprises a microactuator 2, 2 "supported by a substrate 3.
• the substrate 3 is for example made of materials such as glass, plastic or, for power applications, in materials good thermal conductors based on silicon or ceramic
• the substrate 3 has a flat surface 30 on which is fixed the microactuator 2, 2 ".
• the substrate 3 carries for example at least two electrodes 31, 32 (2A and 2B) to be electrically connected to obtain the closure of the circuit electric.
• the microactuator 2, 2 'magnetic carries at least one contact 21, 21 "movable adapted to come electrically connect the two electrodes 31, 32 when the microactuator 2, 2 'is activated.
• the microactuator 2 is composed of a movable element consisting of a membrane 20, for example a parallelepipedal membrane, having a longitudinal axis (A) and connected by one of its ends to a stud 23 anchoring secured to the substrate 3, by means of two arms 22a, 22b of parallel connection.
• the 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 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 electrodes 31, 32, parallel to the surface 30 of the substrate and perpendicular to its longitudinal axis (AT).
• the link arms 22a, 22b form an elastic connection between the membrane 20 and the anchor stud 23.
• the pivoting of the membrane 20 is thus obtained by bending the connecting arms 22a, 22b.
• FIG. 2A in a so-called equilibrium position in which the arms 22a, 22b are not stressed, the membrane 20 is parallel to the plane formed by the surface 30 of the substrate 3.
• a micro-actuator 2 "that can be used in a microsystem according to the invention comprises a mobile element consisting of a rigid membrane, for example a parallelepipedal membrane, having a longitudinal axis (A ').
• this membrane 20 ' is secured to the substrate 3 by means of two arms 22a',
• 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 electrodes 31, 32, parallel to the surface 30 of the substrate and perpendicular to the longitudinal axis (A ') of the diaphragm (20 ").
• this pivot axis (P") of the membrane 20 ' is offset with respect to the median axis parallel which allows to define on the membrane 20 "on either side of its axis (P") of pivoting, two distinct parts, of different volumes.
• the free end of the larger portion of the membrane 20 carries the contact 21 'for closing an electrical circuit.
• the linking arms 22a ", 22b 1 form an elastic connection between the membrane 20 and their respective anchor pads 23a ', 23b' In such a configuration, the pivoting of the membrane 20" is thus obtained by twisting the arms 22a ", 22b 1 binding.
• other configurations may be tailored. as shown in Figure 2B, in a so-called equilibrium position in which the arms are not stressed, the membrane 20 'is parallel to the plane formed by the surface Of the substrate 3.
• microactuator 2, 2 is perfectly usable in a microsystem according to the invention
• the following description lends itself as well to the microactuator according to the first embodiment, as to that according to the second embodiment.
• the microactuator 2, 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, 20 'and the arms 22a, 22b, 22a', 22b 'could be from the same layer of material.
• the connecting arms 22a, 22b, 22a ", 22b" and a lower layer of the membrane 20, 20 ' may be derived from a metal layer. A layer of a material sensitive to magnetic fields is deposited on this metal layer to generate the upper part of the membrane 20, 20.
• Such a configuration can make it possible to optimize the mechanical properties of the arms 22a, 22b, 22a ', 22b connecting, using, to allow the pivoting of the membrane 20, 20 ", a material mechanically more suitable than the material sensitive to magnetic fields.
• the metal layer can act as a contact for closing an electrical circuit.
• the material sensitive to magnetic fields is for example of the soft magnetic type and can be for example an alloy of iron and nickel ("permalloy" Ni 8 O Fe 2 O) -
• FIGS. 3A to 3C 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 a solenoid-type external excitation coil.
• the membrane 20 is therefore able to take two distinct extreme positions.
• FIGS. 3A to 3C in which only the first embodiment of the actuator is shown, in a first extreme position (FIGS. 3A and 3B), the end of the membrane 20 carrying the contact 21 is raised and is not in support against the electrodes 31, 32. The electric circuit is open.
• FIG. 3C In its second extreme position (FIG. 3C), the end of the membrane 20 carrying the contact 21 bears against the electrodes 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 substrate 3 carrying the microactuator 2.
• This first magnetic field B 0 has field lines perpendicular to the surface 30 of the substrate. As shown in FIGS. 3A to 3C, 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 may be generated by a permanent magnet or by an electromagnet.
• a magnetic circuit having as a magnetic source a permanent magnet or an electromagnetic coil 5 can be used to create this first magnetic field B 0. As shown in FIGS. 4A and 4B, this magnetic circuit consists of a permanent magnet (FIG. 4A) or an electromagnetic coil 5 "(FIG.
• a solenoid type excitation coil 4 as shown in Figure 1 connected to a source current, surrounds the substrate 3 and the microactuator 2 supported by the substrate 3 to control the movement of the membrane 20 between its two positions.
• the microactuator 2 is placed in the center of the excitati coil 4. one, in its central channel The passage of a current in the coil 4 excitation causes the pivoting of the membrane 20 from one of its positions to the other of its positions.
• FIGS. 3A to 3C do not show the excitation coil 4. However, it must be considered that in these figures the excitation coil 4 surrounds the magnetic actuator 2 as shown in FIG.
• the substrate 3 supporting the microactuator 2 and surrounded by the solenoid excitation coil 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 FIGS. 4A and 4B. .
• 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 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 first position (FIG. 3A) or in the second position (FIG. 3C).
• the contact portion of the membrane 20 is raised and the electrical circuit is open.
• the contact 21 carried by the membrane 20 electrically connects the two electrodes 31, 32 and the circuit is closed.
• the second magnetic field BS 1 created by the excitation coil 4 generates a magnetic component BP 1 in the magnetic layer of the membrane 20 along its longitudinal axis (A). If the current is delivered in a suitable direction, this new magnetic component BP 1 opposes the component BP 0 generated in the magnetic layer of the membrane 20 by the magnetic field B 0 .
• the component BP 1 generated by the excitation coil 4 is of greater intensity than that generated by the magnetic field B 0 , the magnetic torque resulting from the magnetic field B 0 and this BP component 1 reverses and causes the pivoting of the membrane 20 from its first position to its second position.
• the second magnetic field BSi created by the excitation coil 4 is only transient and is only useful for pivoting the membrane 20 from one position to the other. As represented in FIG. 3C, the membrane 20 is then maintained in its second 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 pair 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 second position.
• the contact 21 carried by the membrane 20 is electrically connect the two electrodes 31, 32 present on the substrate 3.
• the electrical circuit is then closed.
• the membrane 20 must again be rotated to its first position.
• a current is delivered in the excitation coil 4 in a direction opposite to that defined above.
• the magnetic field created by the excitation coil 4 is therefore oriented in a direction opposite to the previous magnetic field BSi.
• This magnetic field generates along the longitudinal axis (A) 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 first 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 4 as well as the density of the magnetic field along the excitation coil 4.
• the solenoid-type excitation coil 4 has a turn density 40 that varies along its length.
• the number of turns 40 is greater at the ends than at the center of the excitation coil 4.
• the magnetic field generated in the solenoid is thus perfectly uniform over the entire length of the excitation coil 4.
• the uniformity of the magnetic field (BSi for example in Figure 3B) generated by the coil 4 excitation is important because it allows to increase the useful volume inside the solenoid.
• the solenoid type excitation coil 4 may be manufactured by printed circuit techniques or by winding a copper wire.
• the magnetic torque existing between the first magnetic field B 0 and the component generated in the membrane 20 is increased.
• the angle x existing between the direction of the first magnetic field B 0 and the surface 30 of the substrate 3 (see FIGS. 5A and 5B). This angle x must be different from 90 °.
• the angle x formed between the direction of the field lines and the surface of the substrate supporting the microactuator can be fixed either by inclining the substrate 3 relative to the direction of the permanent field (FIG.
• a microsystem according to the invention is used for the control of two separate electrical circuits.
• a first substrate 3a carries the electrodes 31a of a first electrical circuit and a second substrate 3b, for example disposed above, parallel to the first substrate 3a, carries the electrodes 31b of a second electric circuit.
• the electrodes 31a, 31b are arranged symmetrically with respect to the longitudinal axis (A) of the membrane 20 of a microactuator 2 according to the invention when the latter is at rest.
• the two substrates are for example connected by connecting elements.
• the microactuator 2 according to the invention is integral with at least one of the substrates 3a, 3b.
• the pivoting diaphragm 20 can therefore pivot between its two extreme positions to close in each of its extreme positions one or the other of the electrical circuits.
• an equilibrium position solid line in FIG. 7
• the two electrical circuits are open and the membrane 20 is parallel to the two substrates 3a, 3b.
• a first extreme position in dashed lines in FIG. 7
• the membrane 20 comes into contact with the first electrode 31a to close the first electrical circuit while in its second opposite extreme position (in dotted lines in FIG. 7), the membrane 20 comes into contact with the second electrode 31b to close the second electrical circuit.
• a microsystem according to the invention may comprise a plurality of identical microactuators 2, 2 'as described above forming a matrix placed in the center of the solenoid type excitation coil 4.
• the microactuators 2, 2 ' are for example organized along several parallel lines.

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• Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Micromachines (AREA)
• Reciprocating, Oscillating Or Vibrating Motors (AREA)
• Electromagnets (AREA)
• Linear Motors (AREA)
• Developing Agents For Electrophotography (AREA)
• Electrochromic Elements, Electrophoresis, Or Variable Reflection Or Absorption Elements (AREA)
• Magnetic Treatment Devices (AREA)
• Mechanical Light Control Or Optical Switches (AREA)

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• 2005
  • 2005-01-10 FR FR0550085A patent/FR2880729B1/fr not_active Expired - Fee Related
• 2006
  • 2006-01-06 DE DE602006012620T patent/DE602006012620D1/de active Active
  • 2006-01-06 EP EP06700703A patent/EP1836714B1/de not_active Not-in-force
  • 2006-01-06 CN CN2006800076856A patent/CN101138060B/zh not_active Expired - Fee Related
  • 2006-01-06 AT AT06700703T patent/ATE459974T1/de not_active IP Right Cessation
  • 2006-01-06 KR KR1020077017940A patent/KR101023581B1/ko not_active IP Right Cessation
  • 2006-01-06 JP JP2007549897A patent/JP4519921B2/ja not_active Expired - Fee Related
  • 2006-01-06 US US11/813,591 patent/US7724111B2/en not_active Expired - Fee Related
  • 2006-01-06 WO PCT/EP2006/050074 patent/WO2006072627A1/fr active Application Filing

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