Patent Application
20220197013
This invention relates to the field of electromechanical microsystems. A particularly advantageous application is the actuation or movement of objects, in particular over relatively large distances. The invention is also applicable to the field of contact detection. It can thus be used to make sensors.
In various applications, there may be a need to move microscopic or even nanoscopic objects and/or a need to sense the movements of such objects. Microsystems are available that allow this.
When these microsystems are actuators, their performance is assessed in particular with respect to the following parameters: the amplitude of the movement, the force deployed and the precision of the movement generated. When these microsystems are sensors, their performance is assessed in particular with respect to the following parameters: the ability to sense a movement over a large amplitude and the measurement accuracy.
In addition, whether the microsystems are actuators or sensors, proper performance is sought in terms of size, energy consumption and ability to operate on a frequency basis.
All known solutions have poor performance for at least one of these parameters. In general, existing microsystems do not perform well enough for a combination of these parameters.
One of the purposes of this invention is to provide an electromechanical microsystem that has improved performance over existing solutions, at least for one of the above-mentioned parameters, or that provides a better compromise regarding at least two of the above-mentioned parameters.
It is a further purpose of this invention to provide an electromechanical microsystem that allows upwards and downward movement of an associated external member or that allows sensing of upwards and downwards movement of an associated external member.
The other purposes, features and benefits of this invention will become apparent from the following description and accompanying drawings. It is understood that other benefits may be incorporated.
Abstract
To achieve at least one of the above purposes, according to one embodiment, an electromechanical microsystem is provided comprising:
At least one part of the deformable diaphragm forms at least one part of a first wall of the said cavity walls.
The cavity is configured to hermetically contain a deformable medium capable of maintaining a substantially-constant volume under the action of a change in external pressure exerted on the deformable medium through one of the cavity walls.
The moving part of each electromechanical transducer is configured so that its movement is a function of the said external pressure change or conversely that its movement causes an external pressure change.
At least one part of the deformable diaphragm has at least one area free to deform, preferably elastically, in response to the said external pressure change.
In addition, the electromechanical microsystem is such that:
The free area may be configured to cooperate with at least one external member so that its deformation causes, or is caused by, a movement of the external member, whereby the proposed solution is capable of moving the external member alternately towards the inside and outside of the cavity and/or sensing a movement of that member alternately towards the inside and outside of the cavity.
In particular, the proposed solution allows the electromechanical microsystem to move the external member into the cavity when the first transducer is loaded and out of the cavity when the second transducer is loaded.
Alternatively or additionally, the proposed solution allows the electromechanical microsystem to sense a movement of the external member towards the inside of the cavity by sensing an electrical current generated by the movement of the first transducer towards the outside of the cavity and a movement of the external member towards the outside of the cavity by sensing an electrical current generated by the movement of the second transducer towards the inside of the cavity.
Furthermore, the proposed solution allows the electromechanical microsystem to form a so-called long-travel actuator, i.e. typically allowing the external member to move over a stroke length of at least 30 μm or even 100 μm (10−6 metre). Similarly, the proposed solution allows the electromechanical microsystem to form a so-called long-travel sensor, typically allowing a movement of at least 30 μm or even 100 μm (10−6 metre) to be sensed.
The electromechanical microsystem as introduced above is thus capable of moving the external member or of sensing a movement of this member, while presenting, in an easily modulable way, depending on the applications in question, a sufficient capability in terms of amplitude of movement and/or a sufficient capability in terms of deployed force and/or a capability in terms of sensing movement over a sufficient amplitude and/or a sufficient capability to operate on a frequency basis and/or a size compatible with the applications in question, and/or a reduced energy consumption.
Optionally, the said at least two electromechanical transducers extend, on at least one of the cavity walls, at a distance from the free area of the deformable diaphragm. To this effect, the said at least two electromechanical transducers are disconnected from (or are not adjacent to) the free area of the deformable diaphragm.
Another aspect of the invention relates to an opto-electromechanical system or microsystem including at least one electromechanical microsystem as introduced above and at least one optical microsystem.
Another aspect of the invention relates to a process of manufacturing an electromechanical microsystem as introduced above, comprising, or even being limited to, ordinary microelectronic deposition and etching steps. The electromechanical microsystem can in fact be manufactured by ordinary microelectronic means, which gives its manufacturer all the benefits of using these means, including a great deal of latitude in terms of sizing, adhesion energy between the different deposits, thickness of the various deposits, etching area, etc.
Based on an example, the process of manufacturing the electromechanical microsystem system includes the following steps:
The purposes, aims and features and benefits of the invention will become clearer from the detailed description of one embodiment thereof which is shown by the following accompanying drawings in which:
The drawings are given as examples and do not place any limit on the invention. They are schematic diagram representations intended to facilitate understanding of the invention and are not necessarily on the scale of practical applications. In particular, the thicknesses of the various layers, walls and members shown are not necessarily representative of reality. Also, the lateral dimensions of the piezoelectric elements, the free area of the diaphragm and/or the stops are not necessarily representative of reality, especially when considered in relation to each other.
Before beginning a detailed review of embodiments of the invention, optional features are set forth below which may optionally be used in combination or alternatively.
According to one example, the said at least one first electromechanical transducer comprises at least one first disc-shaped electromechanical transducer of radius R1 and at least one second electromechanical transducer comprises at least one ring-shaped second electromechanical transducer with a radial extension of R2.
According to the preceding example, at least one first electromechanical transducer and at least one second electromechanical transducer are contained within the boundaries of a circular area of given radius referred to as the “total radius” and designated Rtot, with the said circular area comprising two parts, a first disc-shaped part centred on the said circular area and a second ring-shaped part extending around the first part. The said at least one first electromechanical transducer is contained more particularly within the first part of the circular area and at least one second electromechanical transducer is contained more particularly within the second part of the circular area. The first part of the circular area has a radius R2/3 substantially equal to two thirds of the total radius and the second part of the circular area has an area E1/3 substantially equal to one third of the total radius.
According to the above example, the said at least one first electromechanical transducer further comprises at least one first ring-shaped electromechanical transducer, each first ring-shaped electromechanical transducer extending around the first disc-shaped electromechanical transducer and optionally around another first ring-shaped electromechanical transducer. The said at least one second electromechanical transducer comprises a plurality of second electromechanical transducers each ring shaped and arranged adjacent to and concentric with each other. The total radius Rtot is preferably less than 900 μm, preferably less than 600 μm, and even more preferably less than 300 μm.
According to one example, the said at least one first electromechanical transducer comprises one first disc-shaped electromechanical transducer of radius R1 and at least one second electromechanical transducer comprises at least one second ring-shaped electromechanical transducer with a radial extension of R2.
According to the previous example, the radial extension R2 of the ring formed by the second electromechanical transducer is substantially twice as small as the radius R1 of the disc formed by the first electromechanical transducer.
In addition to or as an alternative to the above feature, the radius R1 of the disc formed by the first electromechanical transducer is at most equal to ⅔ of the sum Rtot of the radius R1 of the disc formed by the first electromechanical transducer and the radial extension R2 of the ring formed by the second electromechanical transducer, and the radial extension R2 of the ring formed by the second electromechanical transducer is at most equal to ⅓ of the sum Rtot of the radius R1 of the disc formed by the first electromechanical transducer and the radial extension R2 of the ring formed by the second electromechanical transducer.
The electromechanical transducers are preferably concentric.
According to one example, the free area is free to deform, preferably elastically, in response to the said external pressure change.
The electromechanical microsystem as introduced above is preferably free of any optical element, such as a lens, in particular a variable focus lens.
According to one example, with the free area configured to cooperate with at least one external member so that its deformation causes, or is caused by, a movement of the external member, the free area of the deformable diaphragm is configured to cooperate with the external member via a pin attached to the said free area, preferably in contact with the said free area, and more specifically in contact with an outer face of the free area.
According to the previous example, the pin may be attached in the centre of the free area of the deformable diaphragm. In this way, it is ensured that the movement of the pin is a translational movement perpendicular to the plane within which the cavity wall is contained, which is partly formed by the deformable diaphragm, when the diaphragm is not deformed.
The pin may be configured to cooperate with the external member via a guide integral with the external member, so as to allow automatic positioning of the external member on the pin.
The pin may be configured to be connected to the external member by adhesion or magnetism, the energy with which the pin adheres to the free area of the deformable diaphragm preferably being greater than that with which the pin adheres to the external member. A connection, possibly removable, between the pin and the external member is thus provided which is largely adjustable in terms of holding force.
According to one example, at least one part of the at least two electromechanical transducers forms a part of the cavity wall that is partially formed by the deformable diaphragm. The electromechanical microsystem according to this feature has a non-through structure, leaving the other walls of the cavity free so as to be able to carry out other functions thereon or so as to allow them to remain inert, for an increased integration capacity in particular in an opto-electromechanical microsystem.
According to one example, the said at least two electromechanical transducers extend, directly or indirectly, over the deformable diaphragm.
The said at least one second electromechanical transducer may be configured such that a movement of its moving part from its equilibrium position to its non-equilibrium position causes an increase in the external pressure acting on the deformable medium and the deformable diaphragm may be configured such that an increase in the external pressure acting on the deformable medium causes a deformation of the free area of the deformable diaphragm tending to move it away from the centre of the cavity (more specifically to move it away from a fixed cavity wall such as the wall opposite to the wall formed in part by the diaphragm). The electromechanical microsystem is thus configured so as to cause a movement of the external member in a first direction, corresponding to a movement of the external member away from the cavity (more specifically, away from a fixed cavity wall such as the wall opposite the wall formed in part by the diaphragm). In addition to the previous feature, the said at least one first electromechanical transducer may be configured such that a movement of its moving part from its equilibrium position to its non-equilibrium position causes an decrease in the external pressure acting on the deformable medium and the deformable diaphragm may be configured such that a decrease in the external pressure acting on the deformable medium causes a deformation of the free area of the deformable diaphragm tending to move it towards the centre of the cavity (more specifically to move it towards a fixed cavity wall such as the wall opposite to the wall formed in part by the diaphragm). The electromechanical microsystem is thus also configured so as to cause a movement of the external member in a second direction, this second direction tending to move it towards the external member of the cavity (more specifically, move it towards a fixed cavity wall such as the wall opposite the wall formed in part by the diaphragm).
The deformable diaphragm is preferably configured so that its free area is capable of being deformed with an amplitude of at least 50 μm, or even of at least 100 μm, or even of at least 1000 μm, in a direction perpendicular to the plane in which it primarily extends when at rest. Without tearing and/or without significant wear, the electromechanical microsystem thus offers the ability to meet the requirements of many different applications requiring a large amount of travel, the latter being defined by the technical field concerned.
The moving part of each electromechanical transducer may have a surface area at least twice as large as a surface area of the free area of the deformable diaphragm. The surface area of the moving parts of the transducers is preferably at least 5 times or even 10 times or even 20 times larger than the surface area of the free area 121 of the deformable diaphragm or even the surface area of the free areas of the deformable diaphragm.
Each electromechanical transducer may be a piezoelectric transducer, preferably comprising a PZT-based piezoelectric material.
At least one of the said at least two electromechanical transducers may be a statically-operating transducer. Alternatively or additionally, at least one of the said at least two electromechanical transducers may be a vibratory-operating transducer with at least one resonant frequency, the said at least one resonant frequency being preferably less than 100 kHz, and even more preferably less than 1 kHz.
The deformable medium hermetically contained in the cavity may comprise at least one, preferably liquid, fluid. The fluid preferably has a viscosity of about 100 cSt (1 cSt=10-6 m2/s) at ambient temperature and pressure.
According to a non-limiting embodiment example, the fluid has a compressibility of between 10−9 and 10−10 Pa−1 at 20° C., for example, of about 10−10 Pa−1 at 20° C., without these values being limiting.
The electromechanical microsystem may further include at least one lateral stop configured to:
The said at least one lateral stop may be supported by the cavity wall that is partially formed by the deformable diaphragm. According to an optional example, the said lateral stop extends away from the cavity.
It is thus possible to:
When the free area of the deformable diaphragm is configured to cooperate with the external member via a pin, the latter may have the following optional features which may optionally be used in combination or alternatively.
The pin may extend from the free area of the deformable diaphragm beyond the said at least one lateral stop.
Alternatively, the pin may extend from the free area of the deformable diaphragm within the at least one lateral stop.
The electromechanical microsystem according to either of the latter two features provides satisfactory adaptability with a wide variety of external members and applications.
The electromechanical microsystem may further comprise a so-called bottom stop supported by the cavity wall opposite the free area of the deformable diaphragm, the said bottom stop extending into the cavity towards the free area. It has a shape and dimensions configured to limit the deformation of the free area of the deformable diaphragm so as to protect the deformable diaphragm, and more particularly its free area, from any possibility of being torn off, in particular when the external member is transferred or stuck. Furthermore, the so-called bottom stop can be shaped to limit the contact surface between the diaphragm and the cavity wall opposite the free area of the deformable diaphragm. Alternatively or cumulatively, the bottom stop may be shaped to limit the contact area between the diaphragm and the cavity wall opposite the free area of the deformable diaphragm. This prevents the diaphragm from adhering to this wall.
The electromechanical microsystem as introduced above may further include a plurality of deformable diaphragms and/or a plurality of free areas per deformable diaphragm.
The said at least one optical microsystem of the opto-electromechanical system as introduced above may include at least one, preferably silicon-based, mirror also referred to as a micromirror.
According to one example, the opto-electromechanical system is configured such that the movement of the moving part of each of the said at least two electromechanical transducers causes a movement of the at least one mirror.
Alternatively or additionally, the opto-electromechanical system may include a plurality of electromechanical microsystems each having a free area arranged opposite a part of the same optical microsystem, such as a mirror. Preferably, the electromechanical microsystem cooperates with the mirror in an area that is not in the centre of the mirror but, for example, in a corner of the mirror. This results in an opto-electromechanical system or microsystem with a large capacity to adapt its optical orientation. Each electromechanical microsystem allowing the part of the optical microsystem opposite which it is arranged to be moved alternately towards the inside and towards the outside of the cavity, a doubling of the amplitude of movement of the optical microsystem can be achieved relative to an electromechanical microsystem allowing only a movement towards the inside of the cavity or towards the outside of the cavity.
The term “electromechanical microsystem” means a system including at least one mechanical element and at least one electromechanical transducer made on a micrometric scale by microelectronic means. The mechanical element can be set in motion (actuated) by a force generated by the electromechanical transducer. The latter can be powered by electrical voltages generated with nearby electronic circuits. Alternatively or additionally, the electromechanical transducer can sense a movement of the mechanical element; the electromechanical microsystem then acts as a sensor.
A “microsystem” is a system whose external dimensions are less than 1 centimetre (10−2 metres) and preferably less than 1 millimetre (10−3 metres).
Most often, an electromechanical transducer acts as an interface between the mechanical and electrical domains. However, the term “electromechanical transducer” refers both to a piezoelectric transducer and a thermal transducer, the latter acting as an interface between the mechanical and thermal domains. An electromechanical transducer may comprise a part moving between an equilibrium, non-loaded position and an out-of-equilibrium, loaded position. When the transducer is piezoelectric, the loading is electrical. When the transducer is thermal, the loading is thermal.
When reference is made to the centre of the cavity, this centre is defined geometrically as the centre of a cavity with an undeformed free area of the deformable diaphragm.
“Below” and “above” mean “not greater than” and “not less than”, respectively. Equality is excluded by the use of the terms “strictly less than” and “strictly greater than”.
A parameter that is “substantially equal to/above/below” a given value means that the parameter is equal to/above/below the given value within plus or minus 20% or even 10% of that value. A parameter that is “substantially between” two given values means that the parameter is at least equal to the smaller given value within plus or minus 20% or 10% of that value and at most equal to the larger given value within plus or minus 20% or 10% of that value.
This schematic diagram may represent a structure with no rotational or revolutionary symmetry about an axis perpendicular and centred with respect to the surface of the deformable diaphragm as shown, as well as a structure extending, for example, in a substantially invariant manner, perpendicularly to the shown cross-sectional view and symmetrical for a first part with respect to a plane perpendicular and centred with respect to the referenced area 121 and for a second part with respect to a plane perpendicular and centred with respect to the referenced area 111a.
Before further describing the various embodiments of the invention shown in the appended figures, it should be noted that each of these illustrations schematically represents an embodiment of the electromechanical microsystem according to the invention which has a non-through structure. More particularly, in the various embodiments shown, each electromechanical transducer 11a and 11b and the deformable diaphragm 12 are both located on the front FAV of the electromechanical microsystem 1. This type of structure is particularly advantageous in that the rear FAR of the electromechanical microsystem 1 can participate only passively, and in particular without deforming, in the actuator and/or sensor function of the electromechanical microsystem 1. More particularly, the rear FAR of an electromechanical microsystem 1 with a non-through structure according to the invention may in particular form a face by which the electromechanical microsystem 1 may be easily fitted to a support (referenced 32 in
However, the invention is not limited to electromechanical microsystems with a non-through structure. In its broadest acceptance, the invention also relates to so-called through-structured microsystems 1 in which at least one of the transducers 11a and 11b and the deformable diaphragm 12 are arranged on mutually distinct walls of the cavity 13, regardless of whether these walls are adjacent or opposite each other.
Each electromechanical transducer 11a, 11b as shown in
In the example shown in
At least one, and preferably each, electromechanical transducer 11a, 11b is preferably a piezoelectric transducer. It is known that such a transducer converts an electrical power supply into a movement of its moving part 111a, 111b from its equilibrium position to a non-equilibrium position and/or converts a movement of its moving part 111a, 111b from its equilibrium position to a non-equilibrium position into an electrical signal. It is thus apparent from this example, but potentially remains true for each of the other contemplated embodiments of the electromechanical microsystem 1 according to the invention, that the latter can operate as an actuator and/or as a sensor. As an actuator, it may allow an external member 2 to be moved up and down, as shown in
At least one, if not each, electromechanical transducer 11a, 11b is even more preferably a piezoelectric transducer comprising a PZT (Lead Titano-Zirconate) based piezoelectric material. In this case, the moving part 111a, 111b of the transducer 11a, 11b is able to move with a more significant movement (due to the piezoelectric coefficient d31) than with many other piezoelectric materials. However, since PZT is a ferroelectric material, such piezoelectric transducers each preferentially operate in a single actuation direction (movement in a single direction of their moving part 111a, 111b) regardless of the polarity of its power supply, whereas a piezoelectric transducer based on a non-ferroelectric material can preferentially operate in both directions (movement in two opposite directions of their moving part 111a, 111b). Alternatively or additionally, at least one or each electromechanical transducer 11a, 11b may be a piezoelectric (non-ferroelectric) transducer based on a material suitable for allowing its moving part 111a, 111b to move in opposite directions relative to its equilibrium position depending on the polarity of its power supply. Such a material is, for example, an aluminium-nitride-based material (AlN).
Alternatively or additionally, at least one or each electromechanical transducer 11a, 11b may be or include a thermal transducer.
The deformable diaphragm 12 may be polymer based, and is preferably PDMS (polydimethylsiloxane) based. The properties of the deformable diaphragm 12, in particular its thickness, surface area and shape, can be configured to provide the deformable diaphragm 12, and in particular an area 121 of the diaphragm that is free to deform, with an expected stretchability, in particular depending on the intended application.
The cavity 13 as shown in particular in
It should also be noted that, in order to more easily ensure the hermetic sealing of the cavity 13:
The walls 132, 133 preferably remain fixed as the diaphragm is deformed.
The deformable medium 14 is in turn capable of maintaining a substantially constant volume under the action of an external pressure change. In other words, it can be an incompressible or weakly compressible medium the deformation of which preferably requires little energy. For example, it is a liquid.
Since at least part of the wall 131 of the cavity 13 is formed by at least part of the deformable diaphragm 12, it is understood that any change in external pressure exerted on the deformable medium 14 can be compensated for by a substantially proportional deformation of the deformable diaphragm 12, and more particularly its free area 121, and/or by a movement of the moving part 111a, 111b of one of the electromechanical transducers 11a, 11b. When one of the transducers 11a, 11b is loaded, this compensation is more particularly related to a conversion of the external pressure change exerted on the deformable medium 14 into a stretching of the deformable diaphragm 12. It is understood that, for the sake of reproducibility of the actuation or motion sensing offered by the electromechanical microsystem 1 according to the invention, it is preferable for any deformation of the deformable diaphragm 12 to be elastic, and not plastic, to ensure that the deformable diaphragm 12 returns to the same state of least stretch, or maximum relaxation, whenever it is no longer loaded.
The deformable medium 14 may more particularly include at least one, preferably liquid, fluid. The parameters of the liquid will be adjusted according to the intended applications. This ensures that any change in external pressure exerted on the deformable medium 14 causes a substantially proportional deformation of the free area 121 of the deformable diaphragm 12. The fluid may be a liquid or liquid based, such as oil, or may be a polymer or polymer based. According to one example, the fluid is based on or consists of glycerine. In this way, in addition to a substantially proportional deformation of the diaphragm 12, the deformable medium 14 is able to occupy, in particular, the volume created by stretching the free area 121 of the deformable diaphragm 12 opposite the centre of the cavity 13.
It is understood from the above that the electromechanical microsystem 1 is configured so that each movement of an electromechanical transducer 11a, 11b causes a change in the external pressure exerted on the deformable medium 14, in order to provide the actuator function of the electromechanical microsystem 1, and conversely, in order to provide the sensor function of the electromechanical microsystem 1. More particularly, when the electromechanical microsystem 1 acts as an actuator, at least a part of one of the electromechanical transducers 11a and 11b is loaded so as to exert an external pressure change on the deformable medium 14 and thereby cause the deformation of the deformable diaphragm 12. Conversely, when the electromechanical microsystem 1 acts as a sensor, the deforming of the diaphragm 12 exerts an external pressure change on the deformable medium 14 which causes a movement of the moving part 111a, 111b of one of the electromechanical transducers 11a, 11b.
As shown in
More particularly, the cooperation between the free area 121 of the deformable diaphragm 12 and the external member 2 may be achieved via a finger, also referred to as a pin 122, which is attached to the free area 121. The terms “finger” and “pin” may be interchanged. The term “pin” is not limited to parts with a constant cross-section, let alone cylindrical parts.
As shown in
Additionally or alternatively, the external member 2 may be structured to include a guide through which the external member 2 cooperates with the pin 122. This guide can also help to prevent the pin 122 from tilting when it moves. It will be seen later that the limitations thus achieved in terms of lateral deflection of the pin 122 may be further enhanced by the provision of at least one lateral stop 15 extending from a part of the wall 131 located outside the free area 121 of the deformable diaphragm 12.
In a non-limiting way, the pin 122 being bonded to or magnetized to the external member 2 may allow the pin 122 and the external member 2 to be made integral with each other. The energy with which the pin 122 adheres to the free area 121 of the deformable diaphragm 12 is preferably greater than that with which the pin 122 adheres to the outer member 2. It will be seen, during the description of the manufacturing process of the electromechanical microsystem 1 shown in
As shown in
In this non-limiting example, the diaphragm 12 has an inner face 12i configured to be in contact with the deformable medium 14 and an outer face 12e. The inner face 12i forms at least a part of the first wall 131 of the cavity 13. In order to easily ensure the sealing of the cavity 13, the inner face 12i of the deformable diaphragm 12 forms the entire first wall 131 of the cavity 13. Each electromechanical transducer 11a, 11b, more specifically the moving part 111a, 111b of the latter, has an inner face 11i facing, and preferably in contact with, the outer face 12e of the diaphragm 12. Each electromechanical transducer 11a, 11b also has an outer face 11e, opposite the inner face 11i, and facing the outside of the electromechanical microsystem 1. In order to easily ensure the sealing of the cavity 13, the inner face 11i of each electromechanical transducer 11a, 11b is preferably entirely in contact with the outer face 12e of the diaphragm 12. One or more intermediate layers may be provided between the outer face 12e of the diaphragm 12 and the inner face 11i of each transducer 11a, 11b. The electromechanical microsystem 1 is configured such that the movement of the moving part 111a, 111b of each electromechanical transducer 11a, 11b causes a deformation of the diaphragm 12 and thus of the first wall 131 which encloses the medium 14.
Note that in
In addition, each electromechanical transducer 11a and 11b can advantageously be integral with the deformable diaphragm 12 over an area 123 located outside the free area 121, and more particularly over an area 123 distant from the free area 121, so that any movement of the moving part 111a, 111b of each transducer 11a, 11b causes, in particular in this area 123, the deformable diaphragm 12 to be stretched or relaxed. Thus, in the example shown in
Still, in the example shown in
It should be noted, however, that in its equilibrium position, the moving part 111a, 111b of an electromechanical transducer 11a, 11b, or even of each transducer, cannot be flat, but may instead exhibit a deflection, known as the equilibrium deflection, which does not detract in any way, in terms of amplitude, from the movement or deflection capability of the transducer 11a, 11b.
With reference to
The cover 18 extends in the xy-plane, for example. It has at least one opening that defines the area in which the moving parts of the said at least two electromechanical transducers 11a and 11b extend. The cover 18 may extend over the entire first face 131 of the cavity 13, when projected in the xy plane, with the exception of an area located around the free area 121 of the deformable diaphragm 12. In this area located around the free area 121 of the deformable diaphragm 12, lateral stops 15 are provided (see below) and which may extend the cover 18.
As shown in
The radius R1 of the disc 11a is at most two thirds of the total radius R1+R2. The radial extension R2 of the area extending around the disc 11a is at most one third of the total radius R1+R2. This ensures that the first electromechanical transducer 11a and the second electromechanical transducer 11b have opposing movements relative to each other, when loaded.
The total radius R1+R2 is preferably less than 900 μm, preferably less than 600 μm, and preferably less than 300 μm.
When the first and second transducers 11a and 11b are spaced apart, the radial extension of this spacing is, for example, between 1 and 100 μm, and is typically 10 μm.
It is understood here that as each electromechanical transducer 11a, 11b has its own moving part 111a, 111b, the moving part of one of the two transducers can be loaded independently from, and in particular alternately to, the moving part of the other transducer. It is then advantageous for the deformation of the moving part 111a of the first electromechanical transducer 11a to oppose, and more particularly be in an opposite direction to, in the z-axis direction, the deformation of the moving part 111b of the second electromechanical transducer 11b. Indeed, it is then possible, even when each of the two transducers 11a and 11b includes a PZT-based piezoelectric transducer, to alternately cause a movement away from and towards the external member 2, depending on which of the two transducers 11a and 11b is loaded. For example, the first electromechanical transducer 11a is configured to move upwards, i.e. away from the centre of the cavity 13, when loaded and the second electromechanical transducer 11b is configured to move downwards, i.e. towards the centre of the cavity 13, when loaded.
In addition, it is advantageous for the radial extension R2 of the second transducer 11b to be about half the radius R1 of the first transducer 11a. In such a configuration, the moving part 111a of the first transducer 11a and the moving part 111b of the second transducer 11b can be moved or deflected with a substantially equal amplitude, when the transducers are alternately and substantially equally loaded.
Also when the partial overlap of the deformable diaphragm 12 by the two transducers 11a and 11b is as shown in
It is immediately apparent from
It is again immediately apparent from
It is again apparent from
The deformation of the moving parts of the transducers 11a and 11c can advantageously oppose the deformation of the moving parts of the transducers 11b and 11d. For this purpose, the transducers 11a and 11c may be contained within a disc of radius less than ⅔ of the total radial extension R1+R3+R2+R4 of the transducers.
Alternatively, the transducer 11a may be contained within a first circular area of radius less than two-thirds of the total radial extension R1+R3+R2+R4 of the transducers and the other three transducers 11b, 11c and 11d may extend beyond the first circular area over an annular area with a radial extension less than one-third of the total radial extension R1+R3+R2+R4 of the transducers.
Another alternative involves considering that the three transducers 11a, 11b and 11c are located in the first circular area with a radius of less than two thirds of the total radial extension R1+R3+R2+R4 and that the fourth electromechanical transducer 11d is located in the annular area with a radial extension of less than one third of the total radial extension R1+R3+R2+R4 of the transducers extending around the first circular area.
As already discussed above with reference to the embodiment shown in
It should be noted here that the electromechanical microsystem 1 according to the second embodiment is not limited to the example shown comprising three transducers 11b, 11c and 11d each having an annular shape. More particularly, the second embodiment extends to a case comprising two annular-shaped transducers and a case comprising more than three annular-shaped transducers.
It should be noted that, regardless of which of the embodiments of the electromechanical microsystem according to the invention is used, each electromechanical transducer 11a, 11b, 11c, 11d is not limited to an annular or disc shape, but may take on other shapes, and in particular a hollow or solid, oblong, oval, triangular, rectangular, etc. shape.
In particular, when the partial overlap of the deformable diaphragm 12 by the electromechanical transducers is as shown in one of
In general, the deformable diaphragm 12 is preferably configured such that its free area 121 is capable of being deformed with an amplitude of less than 1 mm.
The deformation amplitude of the free area 121 is measured along a direction perpendicular to the plane in which the outer face 12e of the diaphragm 12 at rest mainly extends.
Without tearing and/or significant wear, the electromechanical microsystem 1 allows for hydraulic amplification of the action and thus offers the ability to meet the requirements of many different applications requiring a large amount of travel. In this context, the electromechanical microsystem 1 according to each of the two embodiments described above can be defined as an actuator with large upwards or downwards travel.
Still when the partial overlap of the deformable diaphragm 12 by the two electromechanical transducers is as shown in
However, the invention is not limited to the various specific values given above, which can be largely adjusted, depending on the intended application, in particular to obtain a compromise between stretch factor and expected deformation amplitude of the free area 121 of the deformable diaphragm 12.
Note that, in particular when one of the electromechanical transducers is a piezoelectric transducer, it can advantageously be a transducer with a vibratory operation. Its resonant frequency is then preferably lower than 100 kHz, and even more preferably lower than 1 kHz. The vibratory dynamics thus obtained can make it possible to achieve greater deflections than in static operation, in particular by using the related resonance phenomenon, or to reduce the consumption of the electromechanical microsystem for a given deflection.
As already mentioned above, the electromechanical microsystem 1 may further comprise one or more lateral stops 15 supported by the wall 131 of the cavity 13. Each side stop 15 extends more particularly away from the cavity 13.
Relative to at least one of the side stops 15, the pin 122 may extend beyond or within the cavity 13 (see
As shown in each of
A more specific embodiment of the invention than the one described above is shown in
First, it is observed that each electromechanical transducer 11a, 11b shown includes a beam 305 and a piezoelectric material 302 configured to deform the beam 305 when an electrical current flows through it. More particularly, the transducers 11a and 11b share a common beam 305, with their piezoelectric elements 302 being arranged opposite different areas of the beam 305. It is understood that the piezoelectric element 302 of the first transducer 11a is designed to primarily deform a central area of the beam 305, whereas the piezoelectric element 302 of the second transducer is designed to primarily deform an area of the beam 305 around the said central area.
It is further apparent from
This manufacturing process includes at least:
The stops above manufacturing process of the electromechanical microsystem 1 as shown in
The first step in this process is shown in
The second step in the manufacturing process of the electromechanical microsystem 1 as shown in
Note that each of these etching processes can be carried out by lithography, and preferably by plasma etching, or through a wet chemical process.
The third step in the manufacturing process of the electromechanical microsystem 1 as shown in
The fourth step in the manufacturing process of the electromechanical microsystem 1 as shown in
The fifth step in the manufacturing process of the electromechanical microsystem 1 as shown in
The sixth step in the manufacturing process of the electromechanical microsystem 1 as shown in
The seventh step in the manufacturing process of the electromechanical microsystem 1 as shown in
The eighth step in the manufacturing process of the electromechanical microsystem 1 as shown in
Note that, following the above-described steps of manufacturing the electromechanical microsystem 1 as shown in
It should also be noted that the cover 18 discussed above is also formed by carrying out the technological steps shown in
It should be noted here that, if the cover 18 is not necessarily as thick as the said at least one lateral stop 15 (which itself potentially has a role of limiting the travel of the pin 122, unlike the cover 18), it is however, possible, in order to increase the rigidity of the cover 18, if necessary, and/or to better secure the non-moving parts of the transducers, for the cover 18 to have the same composition and the same thickness extension as the said at least one lateral stop 15. The two are then indissociable from each other.
Another aspect of the invention relates to an opto-electromechanical system 3 as shown in
It should also be noted that, because of the possibility offered by each electromechanical microsystem 1 according to the invention of acting on the optical microsystem 31 by moving it alternately upwards and downwards, the achievable angles of tilt of the optical microsystem 31 are thus advantageously increased by an amplitude, relative to electromechanical microsystems which allow the optical microsystem 31 to be acted on in only one direction, upwards or downwards.
It should be further noted that, due to the decentring of the free area 121 of the deformable diaphragm 12 relative to the area 123 over which the electromechanical transducers 11a and 11b extend, it is possible to arrange the free areas 121 of the four electromechanical microsystems 1 as close as possible to the corners or centre of the optical microsystem 31, and in particular potentially closer than would be possible with electromechanical microsystems in each of which the free area 121 of the deformable diaphragm 12 would be centred on the area 123 of the electromechanical transducers. The achievable tilt angles of the optical microsystem 31 are thus advantageously of an increased amplitude.
The invention is not limited to the previously described embodiments and extends to all embodiments covered by the claims.
In particular, other applications than those described above are possible. For example, the electromechanical microsystem 1 can be arranged in a micropump, or even in a micropump array system, in a haptic system, or in a vibratory and possibly acoustic diaphragm system.
| Number | Date | Country | Kind |
|---|---|---|---|
| 20 13823 | Dec 2020 | FR | national |
