EP2018347A1 - Piezoelectric micro-system for the active vibratory insulation of vibration sensitive components - Google PatentsPiezoelectric micro-system for the active vibratory insulation of vibration sensitive components
- Publication number
- EP2018347A1 EP2018347A1 EP20070731337 EP07731337A EP2018347A1 EP 2018347 A1 EP2018347 A1 EP 2018347A1 EP 20070731337 EP20070731337 EP 20070731337 EP 07731337 A EP07731337 A EP 07731337A EP 2018347 A1 EP2018347 A1 EP 2018347A1
- European Patent Office
- Prior art keywords
- Prior art date
- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
- B81B3/00—Devices comprising flexible or deformable elements, e.g. comprising elastic tongues or membranes
- B81B3/0018—Structures acting upon the moving or flexible element for transforming energy into mechanical movement or vice versa, i.e. actuators, sensors, generators
- B81B3/0021—Transducers for transforming electrical into mechanical energy or vice versa
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F15/00—Suppression of vibrations in systems; Means or arrangements for avoiding or reducing out-of-balance forces, e.g. due to motion
- F16F15/005—Suppression of vibrations in systems; Means or arrangements for avoiding or reducing out-of-balance forces, e.g. due to motion using electro- or magnetostrictive actuation means
Microsystem PIEZO VIBRATION INSULATION FOR ACTIVE SENSITIVE COMPONENTS VIBRATIONS
The present invention relates to a piezoelectric micro-system for active vibration isolation of vibration-sensitive components.
It finds particularly advantageous application in numerous fields: micro-electronics, micro-optics, MEMS, MOEMS, electromechanical filters, surface acoustic wave sensors, ultrasonic transducers, etc ..
PRESENTATION OF TECHNICAL FIELD
Stability is a major issue for the use of certain electronic systems such as frequency generators, gyrovribrants or for some accelerometers.
Generally, the objective of any suspension is obviously to limit the acceleration of the system to isolate in the frequency range of stresses.
Conventionally, known solutions propose a compromise between stiffness and damping of the link: mitigation modal suspensions induced increased amortization of the system results in a decrease in the high frequency cutoff and poor insulation in this range.
It is therefore imperative to lower the cutoff frequency by reducing the stiffness of the link, which usually results in a loss of low frequency stability. OVERVIEW OF THE INVENTION
The invention proposes for its new, stable and robust strategy that can effectively solve the problem of isolation compromise.
Thus, the invention provides a microsystem for active vibration isolation, characterized in that it comprises a support comprising a frame and at least two beams intersecting at an intersection zone and carry or are intended to carry an element to be stabilized, said beams having at least a piezoelectric layer and electrodes that define different piezoelectric areas, of which at least two are piezoelectric measuring zones adapted for providing output signals, and are sensitive the deformations of the or beam (s) carrying them, and of which at least one is a piezoelectric activation zone, controlled according to signals output by the piezoelectric measuring zones in a stabilization control law.
The support is preferably made of silicon, but may be other materials.
Advantageously, the system according to the invention comprises two beams cross, one of the beams carrying piezoelectric measurement areas sensitive to deformations of the beam, the other bearing areas piezoelectric activation.
Preferably, the two beams are perpendicular.
For example, the microsystem according to the invention includes three measurement areas, one, central, disposed at the intersection zone between the two beams cross, the other two disposed on one of the two beams, either side of this central zone, with a separation from the latter. Also, it includes two activation zones, arranged on the other beam, on either side of the central zone.
Preferably, the element that is desired to be stabilized is located at the intersection area of the two beams.
Preferably, the microsystem incorporates a component to stabilize filed with the other components of the microsystem.
Preferably, the microsystem comprises means for subsequently receiving the component to be stabilized.
PRESENTATION OF THE FIGURES
Other features and advantages of the invention will emerge from the appended drawings in which:
- Figure 1 is a diagrammatic perspective view of a microsystem according to one possible embodiment of the invention; - Figure 2 composed of Figures 2A and 2B, illustrates the electrode arrangement of the microsystem of Figure 1; 2A is a top view of the microsystem of Figure 1, Figure 2B is a side view of the beam 2b and shows the arrangement of electrodes thereon; - Figures 3a and 3b are theoretical Bode diagrams of a microsystem of the type of Figure 1, a free hand (solid lines) and on the other hand controlled (dotted lines);
- Figure 4 is a photograph in plan view of a microsystem according to one embodiment of the invention.
DESCRIPTION OF ONE OR SEVERAL EMBODIMENTS
The microsystem shown in Figure 1 comprises a silicon substrate that comprises firstly a frame 1 and on the other hand a network of beams 2 extending inside this frame 1 and which carry the suspended mass 3 as we seek to stabilize.
In the example described here, the support 1 in a generally square shape, while the girders 2 network consists of two beams 2a and 2b which extend in cross perpendicularly to each other in the frame 1. specifically, the two beams 2a and 2b extend from the edges of said frame 1, parallel thereto and intersecting the center of said frame 1, at an intersection area 2c, the sprung mass
3 being carried by the joist network at said intersection area 2c.
The different beams (2a, 2b) of the network 2 have a piezoelectric thin film 4 (see Figure 2B), which are superposed on different electrodes that define this layer different zones (4a, 4b, 4c):
• where each the piezoelectric material layer is used as a piezoelectric measurement, responsive to deformation of said beams,
• the other where the material of the piezoelectric layer is used as a piezoelectric activation, controlled as a function of deformations detected by measurement of piezoelectric.
Furthermore, the support 1 and the beams 2a, 2b are on their side opposite to the piezoelectric regions 4a, 4b, 4c a metal layer 10 forming a ground plane (see Figure 2B for simplicity, Figure 2B shows only 2b the beam but by analogy ,, those skilled in the art will represent the electrodes on the beam 2a from Fig 2B).
More specifically, in the example of Figure 1 and Figure 2B, there are provided: that the beams 2a and 2b and the frame 1 that carries them are made of silicon;
4c a piezoelectric measuring area, defined at the intersection zone 2c and sensitive to deformation at the area 2c;
two piezoelectric regions 4a measurement, extending over the silicon of the two branches of the beam 2a on one side and the other of the intersection area 2c, with a separation space 9 with respect to the area piezoelectric 4c; 4a measuring zones are preferably located at the ends of the beam 2a;
two piezoelectric activation zones 4b extending on the silicon of the two branches of the beam 2b on one side and the other of Ia 2c intersection zone; the space 9 between these activation zones 4b 4c of the measurement zone is smaller than the space which separates the measurement zones 4b 4c of said zone areas 4b extending over a greater length of branch and being wider than the zones 4a; 4b the measuring zones are preferably located at the ends of the beam 2b;
A possible arrangement for the electrodes to define these various zones is shown in Figure 2. In the configuration shown, the zone 2c comprises a square electrode 6c, which is connected to a measuring output by a track 7a extending along one arm of the beam 2a to the frame 1.
The height of an edge of the square electrode is for example of the order of 500 micrometers. The electrodes defining the zones 4a and 4b are respectively those referenced 6a and 6b in Figure 2A.
The thickness of the silicon structure (beams 2a, 2b and frame 1) is for example between 0.5 and 100 micrometers, while piezoelectric layer 4 is for example a thin film with a thickness of 0.1 to 10 micrometers.
The width of the beams 2a and 2b is optimized for one hand enable a signal / noise sufficient and secondly allow optimization of activation. For example, the beam 2a which carries the piezoelectric measuring area 4a has a width equal to half the width of the beam 2b which carries the electrode 6b activation. The width of this beam 2b is for example of the order of mm, for a total length of about 5 mm for each of the branches of the beams 2a and 2b.
The electrodes 6a are of a width slightly less than that of the beam 2a, so as to allow passage of the track 7a. Similarly, the electrodes 6b are of a width slightly less than that of the branch
2b. These electrodes 6a and 6b are for example a length equal to half the length of the branches of the beams 2a and 2b
The controlled piezoelectric control law is selected to absorb and compensate for the deformations of the microsystem according to the invention and stabilize actively the suspended mass 3.
Yi signal generated by the piezoelectric region 4c at a deformation of the intersection area 2c is sent with the signals y2 and y3 generated by the piezoelectric regions 4a, 5 on an electronic signal conditioning which generates the voltage V to be applied to areas 4b activation.
5 this electronic signal conditioning (also called microcontroller) comprises a gain controller 5a, as well as input thereof a charge amplifier 5b and outputting a voltage amplifier 5c. Preferably, this electronics 5 is carried by the support (1) of the microsystem.
The gain controller 5a is for example of the type:
G (S) 0> JZ 2 + 3)
where g1, g2 and a and b are constants and where s = iω, ω being the angular frequency of the signal.
Other control laws are of course possible. With such a system, is observed and the fundamental control pumping mode; the other modes of the structure are meanwhile not controlled.
This will induce absolute stability of the mass in a Galilean reference without surge or increase in high frequency transmissibility.
Sensitive components (electrical, optical, etc.) to isolate can be subsequently attached to the microsystem or suspension or be integrated directly thereto, in the case for example of silicon-based components.
Furthermore, the suspension device may advantageously be integrated on printed electronic media (PCB or "Printed Circuit Board") or complete systems.
The piezoelectric layers are, for example ceramic PZT (Lead titanate zirconate) sol gel, integrated directly on SOI substrates (Silicon on insulator).
Other piezoelectric materials can be used as the aluminum nitrate (AlN), zinc oxide (ZnO), and other similar perovskites to PZT, also depositing by other techniques such as PVD (physical vapor deposition) and CVD (chemical vapor deposition).
A cross structure was notably performed (see figure 4) from an SOI wafer (Silicon On Insulator) which contained a layer of silicon (Si) single crystal 5 microns thick on an oxide layer (buried oxide) of about 1 .mu.m, while bonded to a silicon (Si) substrate. After deposition and patterning of the lower electrode lead (Pt) one of PZT, the upper gold / chrome electrode (Au / Cr), the substrate beneath the structure is excavated (from the lower side) until 'to the buried oxide ( "buried oxide") by dry etching, and the shape of a cross is released by dry etching from the top surface. For the etching of the substrate, one could also use the anisotropic wet etching method Si in a basic solution (such as p. Eg. Potassium hydroxide KOH).
The first tests show a 90% higher return on a Si substrate 10 centimeters in diameter.
No deterioration of the system is observed (fatigue, delamination).
Figures 3a and 3b illustrate the Bode diagrams obtained through such active control.
The solid curve is representative of a free microsystem; the dotted line curve represents an active controlled system according to the invention,
As can be seen in Figures 3a and 3b, the resonance is greatly reduced. In this way, there is provided a system for an attenuation of at least 40 dB per decade, and a high attenuation at the resonance frequency. It is also noted that the peak before resonance ( "overshoot") is relatively low which allows not to have amplification of the system response at frequencies related to the peak.
Finally, the proposed microsystem allows a substantially smooth linear control, that is to say without retransmission of high frequency energy.
Finally, the microsystem according to the invention can be integrated or arranged on a circuit board or an optical medium.
Priority Applications (2)
|Application Number||Priority Date||Filing Date||Title|
|FR0603494A FR2900144B1 (en)||2006-04-20||2006-04-20||Microsysteme piezoelectric active vibration isolation for the components that are sensitive to vibration|
|PCT/FR2007/000676 WO2007122330A1 (en)||2006-04-20||2007-04-20||Piezoelectric micro-system for the active vibratory insulation of vibration sensitive components|
|Publication Number||Publication Date|
|EP2018347A1 true EP2018347A1 (en)||2009-01-28|
Family Applications (1)
|Application Number||Title||Priority Date||Filing Date|
|EP20070731337 Withdrawn EP2018347A1 (en)||2006-04-20||2007-04-20||Piezoelectric micro-system for the active vibratory insulation of vibration sensitive components|
Country Status (3)
|EP (1)||EP2018347A1 (en)|
|FR (1)||FR2900144B1 (en)|
|WO (1)||WO2007122330A1 (en)|
Families Citing this family (1)
|Publication number||Priority date||Publication date||Assignee||Title|
|DE102011015800A1 (en) *||2011-04-01||2012-10-04||Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.||A device for mechanical decoupling of vibrations|
Family Cites Families (2)
|Publication number||Priority date||Publication date||Assignee||Title|
|JPH07190782A (en) *||1993-12-27||1995-07-28||Nikon Corp||Vibrational angular velocity meter|
|JP3307101B2 (en) *||1994-08-31||2002-07-24||株式会社村田製作所||An angular velocity sensor|
Non-Patent Citations (1)
|See references of WO2007122330A1 *|
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Effective date: 20090506
Inventor name: DELOBELLE, PATRICK
Inventor name: MURALT, PAUL
Inventor name: COLLET, MANUEL
Inventor name: BABOROWSKI, JACEK
Inventor name: WALTER, VINCENT
Inventor name: MEYER, YANN
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Effective date: 20141101