DE10008752B4 - Piezoelectric actuator - Google Patents

Abstract

Single or multi-layered piezoelectric actuator which is operated by an actuator voltage applied to each layer of piezoceramic and which is simultaneously operated with at least one of the layers as a sensor for measuring the detection of the actuated by the actuator voltage forces or deformations of the piezoceramic, wherein the sensor layer / s in addition to the applied actuator voltage, a signal voltage source is connected, which emits as auxiliary excitation voltage (U _S ) a frequency-coded, a mono- or multifrequent or a frequency-variable sensor signal to the respective sensor layer / s, and wherein the sensor layer / s also a measuring circuit connected to the evaluation of the frequency response, which is based on the measurement principle "Resonator force transducer", the exploitation of the change in the material's own vibration behavior when force is based on a decoupled from the actuator voltage (U _A ) measured signal (U _M ) is obtained, which is a "response" signal containing the frequency response to the sensor signal.

Description

The The invention relates to a single or multilayer piezoelectric Actuator, created by a piezoceramic layer applied to each layer Actuator voltage is operated and that with at least one of the layers at the same time as a sensor for metrological Detection of the actuated by the actuator voltage forces or deformation of the piezoceramic is operated.

Furthermore The invention relates to mechanical arrangements, electrical circuits and systems with multiple piezoelectric actuators, regulator circuits using piezoelectric actuators and applications of piezoelectric actuators.

piezoelectric Actuators have a high energy density, a fast response as well as a simple construction. They can be in series or in parallel be operated switched. By applying an electrical voltage becomes a piezoceramic solid deformed, wherein the deformation is proportional to the voltage. There piezoceramic actuators an "electromechanical Drift ", requires the control of such actuators so far - depending on Task - one additional Displacement and / or force measurement, since with them without such a scheme Positions can only be roughly made, especially the travel path with a relatively big mistake is afflicted.

Furthermore sets a piezoceramic actuator usually only slight deformation paths back, which is why an external extra Displacement and / or force measurement is expensive, complicated and inaccurate. typical Applications are therefore currently rough, (highly) dynamic positioning tasks with high power requirement and small adjustment paths.

The use of a piezoceramic as a piezoelectric actuator is for example off US 5,473,214 A known.

If a piezoceramic is used as a sensor, as for example US 4,831,304 A and US 4,835,436 A is known, then results from an externally applied deformation an electrical voltage on the ceramic body. If the applied force or deformation remains constant, however, it is practically impossible to measure a proportional voltage signal, since this voltage is reduced again by the internal resistance of the measuring electronics and the piezoceramic. Typical measurement tasks are therefore dynamic measurements, which, however, are associated with relatively large inaccuracies.

Out DE 31 03 061 A1 . DE 32 41 601 A1 and WO 98/3740 A1 actuators with a piezoceramic plate stack with at least one piezoelectric disc are known in which for monitoring the forces or the Auslenkverhaltens of the actuator or to obtain control and controlled variables at least one piezoelectric disk of the stack at least partially is used as a measuring sensor.

Out DE 198 04 196 A1 It is known to diagnose piezo-mechanical systems with regard to their oscillation and frequency behavior, wherein a threshold value query of a piezoelectric signal is performed. An output signal is then changed if the piezo signal exceeds or falls below a threshold value.

The measuring principle of a resonator force transducer is for example off DE 30 13 185 A1 . US 3 479 536 A such as US Pat. No. 3,470,400 known; In this case, the use of a piezoelectric element is described as a vibrator for this purpose in these publications. To measure force piezoelectric quartz resonators are used, which receive the necessary vibration energy from an oscillator via metal electrodes and their turn to be taken on the oscillator oscillation frequency is proportional to each applied externally to the piezoelectric element force.

Of the Invention is based on the object, a piezoelectric actuator so educate and shape that he in a use as Sensor independent of time accurate measurement results its piezoforming provides what is then to be exploited Actuator and sensor component to connect and to perform a control of the actuator at local proximity of the sensor easily. In addition, supposedly by the invention advantageously provided with sensor evaluation electrical Circuits and mechanical arrangements with several cooperating piezoelectric actuators, control circuits, systems with several also as a sensor effective piezoelectric actuators and applications for at the same time as a sensor working piezoelectric actuators are specified.

According to the invention, which relates to a single- or multi-layer piezoelectric actuator of the type mentioned above, a signal voltage source is connected to a sensor layer (s) in addition to the applied actuator voltage, the auxiliary excitation voltage being a frequency-coded, mono- or multifrequency or frequency-variable sensor signal delivers the relevant sensor layer (s). On the sensor layer / s also a measuring circuit for the evaluation of the frequency response is connected, the application under tion of the measuring principle "resonator force transducer", which is based on the utilization of the change in the material inherent vibration behavior when force is obtained on the basis of a decoupled from the actuator voltage taken measuring signal, which is a frequency behavior containing "response" signal to the sensor signal.

One Problem with the use of piezoceramic as a sensor was so far, that at Relative measurement of paths or forces reasonably accurate measurement results can only be achieved by evaluating the piezo voltage. This problem let yourself in accordance with the principle underlying the invention bypass another measurement of the piezoforming, another one physical effect is based, namely that of a mechanical Burden dependent Oscillation behavior of the piezoceramic. A similar behavior is for example known from a guitar string, where: the higher the mechanical stress is, the higher are the natural frequencies the string. The analogue effect is lost even with rigid bodies mechanical load on; furthermore, they increase with increasing mechanical Load the natural frequencies proportionally.

This Effect is time independent. Any mechanical load is thus clearly a specific one Frequency spectrum assigned. Absolute measurements are therefore through Evaluation of the actively excited natural frequency oscillation or the Vibration frequency spectrum very precise possible.

For this The actuator voltage can be directly modulated on a sensor signal and the actuator voltage can be, for example, by frequency filtering be evaluated. In order to prevent mutual influences, are advantageously actuator voltage and sensor signal voltage separated by circuitry. In addition, it is appropriate to the Sensor locally close to the actuator evaluate and also the regulation of the actuator locally perform, for example, by a regulator circuit which, except that they Performs sensor evaluation, simultaneously controls the actuator voltage. As input receives a such regulator circuit over a signal input a rule, so that they either have a Signal output can also deliver a path or force signal.

Of the Piezoelectric actuator and sensor according to the invention combines the known electromechanical properties of piezoceramic components, where he also serves as a sensor and actor. The sensor provides a load-proportional absolute signal in this system, that does not depend on time. By building a control loop, this compo can ment as full adjustable mechatronic linear actuator operated with sensor feedback be with both a weggeregeltes as well as a force-controlled or a weg- and force-controlled behavior is achieved.

• • Vermessung der Eigenfrequenz und der Dämpfung durch Anregung und Beobachtung der Sprung- und Impulsantwort des Sensors.
• • Anregung mit einer oder mehreren frequenzkonstanten Sinusschwingungen und Beobachtung der Veränderungen von Amplitude und/oder Phase der Antwort.
• • Anregung mit einem Wobbelsignal und Beobachtung der Amplitudenantwort. Vermessung von charakteristischen Merkmalen, wie z.B. steilen Kanten, Maxima, ..., im Amplitudengang.
• • Anregung mit breitbandigem, in idealer Weise weißem Rauschen und Beobachtung der Antwort im Frequenzbereich.
• • Auswertung des Phasenganges.

To evaluate the sensor information, the following is executed:
The information about the force acting on the piezoelectric actuator / sensor actuator and the associated deformation is determined from the change in the natural vibration behavior of the piezoceramic. The natural vibration behavior can be analyzed in different ways.

• • Measurement of the natural frequency and the damping by excitation and observation of the jump and impulse response of the sensor.
• Excitation with one or more frequency-constant sinusoids and observation of the changes in amplitude and / or phase of the response.
• Excitation with a sweep signal and observation of the amplitude response. Measurement of characteristic features, such as steep edges, maxima, ..., in the amplitude response.
• • Excitation with broadband, ideally white noise and observation of the response in the frequency domain.
• • Evaluation of the phase response.

A Evaluation in the frequency domain may be circuitically, e.g. by a tunable or multiple frequency constant filter, which the assessment of the amplitude in certain frequency ranges allow. Another possibility is the evaluation of the spectrum by calculation of the Fourier transformers. For this purpose, for example, a digital signal processor used with which the Fast Fourier transform of the response signal is calculated and evaluated.

The Invention will be further explained below with reference to drawings. It demonstrate:

1 the functional principle of a piezoelectric actuator based on a summarized in a picture mechanical arrangement and its wiring;

2 the functional principle of a piezoelectric sensor based on a summarized in a picture mechanical arrangement and its wiring;

3 the mechanical arrangement and wiring of a component combination of piezoelectric actuator and sensor without compensation;

4 the mechanical arrangement and wiring of a component combination of piezoelectric actuator and sensor with compensation by a differentially applied sensor signal voltage;

5 the mechanical arrangement and wiring of a component combination of piezoelectric actuator and sensor with compensation by differential connection of the actuator voltage;

6 the mechanical arrangement and wiring of a component combination of piezoelectric actuator and sensor with complete separation of Sensorsi signal and actuator voltage by means of a bridge circuit;

7a and 7b an application example of the invention, in which are combined to form a caused by a piezoelectric actuator beam deflection two plano-convex lenses in an optical beam path, and

8a and 8b one opposite the 7a and 7b extended application example of the invention, in which a field of plano-convex lens pairs in an optical beam path is to form a caused by a piezoelectric actuator beam deflection.

In 1 is the principle of operation of a piezoelectric actuator shown. At the two end connection surfaces 10 and 10 ' a piezoceramic 1 an actuator voltage U _{A is} supplied. The of the piezoceramic 1 externally output at its two end faces force F is proportional to the actuator voltage U _A. At a constant force F, the actuator voltage U _{A is} proportional to the change in length of the piezoceramic 1 , The actuator voltage U _A is variable according to magnitude and sign.

In 2 is the principle of operation of a piezoelectric sensor shown. Here, a force F acts from the outside on the end faces of the piezoceramic 1 , One at the two end connection surfaces 10 and 10 ' With the sensor excitation unchanged, the measured signal voltage U _M changes due to an auxiliary excitation voltage U _S as a function of the externally applied piezoceramic 1 acting force F. The additional, the sensor signal forming auxiliary excitation voltage U _S is at the two end-side pads 10 and 10 ' for measuring the frequency behavior of the piezoceramic 1 created. Depending on the measuring method used in each case, it can be, for example, a pulse voltage, a noise signal or any kind of alternating voltage with a possibly variable frequency.

The tapping of the Meßsignalspannung U _M is possible in different ways. For example, this can be done in the same branch in which the additional auxiliary excitation voltage U _{S is} applied; but also a tap on an additionally applied on a piezoceramic plate auxiliary electrode or on a separate, mechanically coupled piezoelectric element is possible.

In 3 is the mechanical arrangement and wiring of a component combination of piezoelectric actuator and sensor shown without compensation. This is a minimal arrangement of a sensory actuator, without a compensation circuit is provided. At the two end connection surfaces 10 and 10 ' the piezoceramic 1 the actuator voltage U _{A is} supplied. The of the piezoceramic 1 externally output at its two end faces force F is proportional to the actuator voltage U _A. At a constant force F, the actuator voltage U _{A is} proportional to the change in length of the piezoceramic 1 , The actuator voltage U _A is variable according to magnitude and sign.

One at the two end connection surfaces 10 and 10 ' From the actuator voltage U _A removed measuring signal voltage U _M changes with constant sensor excitation by an auxiliary excitation voltage U _S as a function of the outside of the piezoceramic 1 acting force F. The auxiliary signal excitation voltage U _S forming the sensor signal is applied to the two terminal pads 10 and 10 ' for measuring the frequency behavior of the piezoceramic 1 created. In the principle of operation 2 and the arrangement according to 3 If the actuator voltage U _{A is} not decoupled from the auxiliary arrangement voltage U _S or the measurement signal voltage U _M. In 2 and 3 Although separate electrodes are provided, but mechanically all electrodes are the same and thus all electrical paths equally burdened, ie coupled.

It can be just like at 2 depending on the particular measuring method used, for example, be a pulse voltage, a noise signal or any kind of alternating voltage with optionally variable frequency. The tapping of the measuring signal U _M is possible in different ways. For example, this can be done in the same branch in which the additional auxiliary excitation voltage U _{S is} applied; but also a tap on an additionally applied on a piezoceramic plate auxiliary electrode or on a separate, mechanically coupled piezoelectric element is possible.

In the 2 and 3 the Meßabgriff for the decrease of the Meßsignalspannung U _M is shown only schematically as a parallel to the auxiliary excitation measuring instrument whose technical Aus management is irrelevant to fundamental considerations. The basic decoupling of sensor and actuator, which is the same piezoceramic 1 use is crucial. So on the one hand, the applied auxiliary excitation voltage U _S should not lead to an outwardly visible defor determination of the overall arrangement, on the other hand, the measuring signal voltage U _{M should be} free of superimpositions by the applied actuator voltage U _A. This also applies to the arrangements described below.

In the subsequently described arrangements according to the 4 to 6 several piezoceramics are mechanically arranged in series, which is generally referred to as a piezo stack.

In this case, the actuator voltage U _A must be applied to the piezo stack so that caused by the actuator voltage U _A deformations of the piezoceramic individual elements ( 1 and 2 in the 4 and 5 ; 1 to 4 in 6 ) throughout the stack, while the auxiliary excitation voltage U _S must be applied so that the individual deformations caused thereby over the entire stack cancel each other out.

The forces F, the amount of which is variable, are compressive forces, since tensile forces could mechanically destroy the piezoceramic. In conventional ceramic piezo actuators, a mechanical bias is applied to the actuator in order to be able to apply it to similarly high positive and negative voltages, without risking a Umpolarisieren. Hereinafter, this structure will be used, although the circuits presented below can also be adapted to electrostrictive materials, the extent of which depends only on the amount, but not on the sign of the applied actuator voltage U _A.

In the 4 is the mechanical arrangement and wiring of a piezo stack combination of piezoelectric actuator actuator and sensor shown with compensation by a differentially applied sensor signal voltage. The piezo stack consists in the 4 from two piezoceramic individual elements arranged mechanically in series 1 and 2 , The end connection surface 11 of the piezoceramic single element 1 is with the end-side pad 20 of the piezoceramic single element 2 electrically and mechanically directly connected. The sensor signal voltage consisting of two auxiliary excitation voltages U _S1 and U _S2 is differentially superimposed on the applied actuator voltage U _A which generates the force F on the outside of the piezo stack.

This is done by the one pole of the actuator voltage U _A with the pads 11 and 20 and the other pole is connected to one pole of each of the sources of the auxiliary excitation voltages U _S1 and U _S2 , the other pole of which is connected to the end-side pad 10 of the piezoceramic single element 1 or at the end-side pad 21 of the piezoceramic single element 2 connected. If the two auxiliary excitation voltages U _S1 and U _{S2 are the} same, then the deformation of the two piezoceramic individual elements caused by them rises 1 and 2 in the sum over the piezostack.

At the in 4 The arrangement shown is to generate the sensor signal voltage in the form of the auxiliary excitation voltages U _S1 and U _S2 for differential connection twice. To evaluate the difference of the decoupled from the actuator voltage U _A Meßsignalspannungen U _M1 and U _{M2 must be} formed to decouple the measurement result of influences of the variable actuator voltage U _A.

In the 5 the mechanical arrangement and the wiring of a piezo stack combination of piezoelectric actuator and sensor with compensation by differential connection of the actuator voltage U _{A is} shown. The piezo stack consists in the 5 from two piezoceramic individual elements arranged mechanically in series 1 and 2 , The end connection surface 11 of the piezoceramic single element 1 and the terminal pad 20 of the piezoceramic single element 2 are electrically and mechanically connected directly. The applied, the force F at the piezo stack generating actuator voltage U _A is differentially superimposed on the sensor signal voltage U _S1 .

This is done by the one pole of the sensor signal voltage U _S1 with the pads 11 and 20 and the other pole is connected to one pole of the two sources of the actuator voltage U _A , whose other pole at the end-side pad 10 of the piezoceramic single element 1 or at the end-side pad 21 of the piezoceramic single element 2 connected. The actuators are arranged so that they behave the same at the same actuator voltage U _A , for example, both expand. Here, the sensor signal voltage US1 does not affect the overall deformation. The measuring signal voltage U _M is decoupled in parallel to the sensor signal voltage U _S1 decoupled from the actuator voltage U _A. When in the 5 arrangement shown are the actuator voltages U _A for differential connection twice to produce.

In the 6 is the mechanical arrangement and wiring of a piezo stack component combination of piezoelectric actuator and sensor with complete separation of sensor signal and actuator Voltage represented by a bridge circuit. The piezo stack in the 6 consists of four piezoceramic individual elements arranged mechanically in series 1 . 2 . 3 and 4 , There are the first end face 11 of the piezoceramic single element 1 and the terminal pad 20 of the piezoceramic single element 2 , to the second, the terminal pad 21 of the piezoceramic single element 2 and the terminal pad 30 of the piezoceramic single element 3 and third, the end pad 31 of the piezoceramic single element 3 and the terminal pad 40 of the piezoceramic single element 4 electrically and mechanically connected directly.

The actuator voltages U _A act on the four piezoceramic individual elements 1 to 4 so that they show the same behavior, for example, all expand. The sensor signal voltages US are directed so that the deformations of two piezoceramic individual elements 1 . 2 respectively. 3 . 4 cancel each other out and thus cause no change in length in their total over the entire piezo stack. In this arrangement, it is avoided that one of the voltages must be generated twice. It is also only a sensor signal voltage to evaluate.

To the same size deformations as in the in the 4 and 5 To achieve arrangements shown, the voltages to be applied in the bridge arrangement must be twice as large, so be 2U _A and 2U _S , as they are each connected to two series piezoceramic elements 1 . 2 respectively. 3 . 4 Act. At this in 6 shown mechanical arrangement and electrical wiring is a complete compensation of all unwanted influences by an internal coupling from the sensor to the actuator, and vice versa. The measuring signal voltage U _M is removed in a decoupled manner lying parallel to the sensor signal voltage U _S.

The voltages U _S and U _A are usually at a different level. Most of the sensor signal voltages US are much lower than the actuator voltages U _A , so the former, ie U _S , even without compensation, have only a small to negligible influence on the actuator.

The above based on the 4 to 6 described mechanical arrangements of similar piezoceramic elements with the circuits shown are particularly well suited to compensate for mutual interference of the actuator and sensor and thus to increase the resolution of the linear actuator. In a purely physical way, a complete electrical and mechanical compensation is achieved here and thus greatly simplifies both the sensor evaluation and the actuator control. Also, there is no need to resort to signal post-processing; There are also no compensation tables or similar auxiliary tools needed that would slow down a scheme greatly.

The Method according to the invention can be said to that effect expand that for example, an absolute length measurement of the piezoceramic based on the structure-borne sound transit time measurement be supplemented can. Then the mechatronic linear actuator is completely powerful, Distance and voltage controllable.

The underlying principle of the invention is not only piezoceramic Linear actuators applicable, but also applies to all others Transfer piezo actuators, such as on bending, turning or pushing actuators.

It can also uses other materials than piezoceramic material become. The actuator / sensor according to the invention can be made of one of the piezoceramics exist in terms of the physical properties of similar material, in which the application of an electrical voltage or an electrical Current leads to a deformation. Magnetostrictive solids, quartz, Bimetallic arrangements and materials where the thermal expansion or structural transformation used as an actoric effect (electrorheological fluids), into consideration.

in the following are execution options and further developments of the invention explained. In addition, are still advantageous and appropriate further education, Type of control and applications in the claims specified.

at a series connection of a plurality of piezoelectric actuators can in a variant, the sensor signal is switched only one of these actuators, wherein the measurement signal preferably only at this one actuator removed and evaluated. Thus, in direct series arrangement, the voltage level of the sensor and measuring signal significantly below the voltage level of the actuator voltage.

The Level of the actuator voltage can advantageous for a working under medium operating load actuator be sized so that they compared to the Level of the sensor signal voltage and the Meßsignalspannung are significantly higher.

It may be an arrangement of a plurality of piezoelectric actuators in the form of a series arrangement or parallel connection of any number of Sensors / actuators are provided, wherein preferred designs have the same number of similar serially arranged actuators in parallel branches Piezoelectric actuators according to the invention can be advantageously for the construction of a regulator circuit, for example, for force control, provide what will be explained below.

In Such a regulator circuit is preferably a device for Generation of a frequency and possibly amplitude modulated Sensor signal forming auxiliary excitation voltage and a measuring circuit for evaluation of the measuring signal provided according to amplitude and frequency. The device for production the frequency and possibly amplitude modulated sensor signal forming auxiliary excitation voltage is preferably a wobble generator or a tunable resonant circuit. The measuring circuit for evaluating the Measuring signal after Amplitude and frequency is expediently designed so that they clearer emphasis on the characteristic of the natural vibration behavior performs a comparison with the sensor signal.

The measuring circuit consists of at least one sensor signal input, at least one measuring signal input, at least one comparator for comparing the sensor signal and the measurement signal and at least one output interface for controlling the actuator voltage. It can be a carrier frequency generator be provided, the one to be evaluated in a preferred manner close to the Frequency carrier frequency generated, whereby a beating between sensor or measuring signal or their differential voltage signal and the voltage signal of the carrier frequency is stimulated, which is then evaluated in a different frequency range becomes. In the measuring circuit can also have an output interface for external display of the voltage or Wegmeßsignals be provided.

at a regulator circuit according to the invention is the frequency and possibly amplitude-modulated sensor signal forming auxiliary excitation voltage excited in a frequency band in which characteristic natural frequencies lie of the piezoelectric actuator. The clearer a natural frequency in the surrounding frequency band by the height of Meßsignalamplitude stands out, the the evaluation is easier. For each type and size can suitable frequencies effortlessly be determined experimentally. In the evaluation of the load-dependent natural frequency shift Optionally, known methods may be used, e.g. Fast Fourier Transform (Fast Fourier Transform; FFT), the frequency-selective excitation of oscillating circuits or the Evaluation of the amplitude over the frequency through a digital signal processor (DSP). The sensor signal can be in the excitation of a voltage jump, a voltage pulse or a noise signal, in which case the response as a measurement signal is evaluated.

It Systems of several sensors / actuators are possible, two or more in parallel Acting sensors / actuators contain independently controlled can be controlled. In the case of two similar actuators arranged in parallel, for example a simultaneous expansion of both actuators for parallel feed and a combination of expansion of the one actor and simultaneous shortening of the other actor for a turn can be used. Any combinations of these are controllable.

By the operation of more than two parallel or spatially arranged, with each other directly or via Intermediate links associated actuators can actuators with multiple Degrees of freedom are built, the number of independent degrees of freedom maximum as high as the number of actuators. As an application example can couple a combination of six spatially Actuators are provided, which is a so-called steward platform (= Hexapod), which with the given by the invention Actuator / sensor principle for the first time simply fully realizable becomes feasible.

in the Following are some particularly advantageous applications of the invention.

piezoelectric Sensors / actuators according to the invention can be particularly in Frame of a car brake system with a piezoelectric brake used on at least one sensor / actuator as Linearvorschub-, Shearing or bending actuator e.g. for controlled adjustment of the brake pads Disc brake in motor vehicle, but also in the railway sector based.

A further possible use exists in linear actuators in fine positioning, for example in precision machining machines. Here, priority is a combination of the actuator or the actuators with an electric motor and / or possibly with transmissions possible, for example as a linear actuator or turntable for robot drives, machining centers, Machine tools and the like, wherein the actuator or the actuators are not used as the main drive, but serve as complement to brake the drive motor or at standstill self-locking to effect the drive. The self-locking can be done via a mechanical preloaded "safety" brake made be regulated only by energizing the actuator or the actuators to open is.

A further advantageous application of the piezoelectric actuator according to The invention consists in the possibility the fine dosing of substances, especially of drugs in the clinical area or in the mixture for generating drug mixtures, e.g. in pharmacies.

The The invention can also be applied to vibration excitation and damping arrangements be used in mechanical structures, such as in particular Aircraft wings, Helicopter rotors, in aircraft, railway or passenger car chassis, with vibration-decoupled suspensions of aggregates, motors, generators and brakes, in building foundations and at railway tracks.

Of further can be sensor / actuator elements according to the invention in an advantageous In the case of injection systems, in particular those or diesel injection pumps for the motor vehicle, ship, aircraft and stationary engine area accomplished are, and at such for Apply applications in the chemical, power plant and plant area.

Also for valve adjustments both in the fine adjustment range and for highly dynamic Drives, such as valves in internal combustion engines, powered by a piezo stack of actuators or a piezo-bending actuator, also for the force vehicle, ship, aircraft and stationary engine area as well for applications in the chemical, power plant and equipment sector, the invention can be successfully deploy.

at Paint spraying systems, in particular for printing tasks, e.g. the color dosage and the "splash" in PC black and white and color printers or for painting jobs in packaging, printing or vehicle painting can Sensor / actuator elements according to the invention also used successfully become.

A use possibility the piezoelectric actuator according to the invention is also in the Mirror fine adjustment, in particular by one or two independent orthogonal Axes, for example optical measuring instruments, beam deflection systems, Scanners, laser processing machines, slide or similar projectors as well as measuring setups.

As well is a problem with piezoelectric sensor / actuator elements executable Fine adjustment of a microlens array or a mirror for two-dimensional beam deflection possible, for example, used for the adaptive car headlight adjustment or in the lighting technology for the building and Landscape lighting.

In the 7a and 7b is still an application example of the invention shown in which two plano-convex lenses L1 and L2 are combined in an optical beam path to form a caused by a piezoelectric actuator beam deflection. As 7a for the still undeflected beam shows, the two lenses L1 and L2 lie with their flat surfaces on each other. As the 7b shows, the two convex lenses L1 and L2 in the beam path relative to the original state shown in dashed lines down together, which is carried out by means of a piezoelectric actuator / sensor element according to the invention. The beam is deflected downwards. This is also the case when only one of the two lenses L1 and L2 is moved. In the arrangement for lens shift is in the 7a and 7b the actuator shown as a cylinder Z schematized.

This deflection also works with several parallel lenses L1 and L2, like the 8a and 8b in one opposite the 7a and 7b show extended application example of the invention, in which for forming a caused by a piezoelectric actuator / sensor element beam deflection is a field plano-convex lens pairs in an optical beam path. As 8a shows for the still undeflected beam, the two parallel, each consisting of lenses L1 and L2 lens fields F1 and F2 or lens discs in the beam path, the paired lenses L1 and L2 with their flat surfaces rest on each other The lenses L1 and L2 of a pair lie exactly opposite with undeflected jet. As the 8b shows, the two convex lens panels F1 and F2 in the beam path relative to the original, dashed state shown shifted from each other, which is carried out by means of a piezoelectric actuator / sensor element according to the invention. The beam is deflected downwards.

Small paths can also be covered by deformation of a solid. For precise and rapid deformation of a solid can be used according to the invention trained actuator / sensor element. The masses to be moved are minimal in comparison to a conventional optics. The solid body consists of two interconnected transparent plastic lens panels or disks F1 and F2. If the arrangement is chosen as in the 8a and 8b As shown, deformation in only one direction can lead to relative beam deflection in one direction. If the beam is to be deflected in two directions, the two lens fields F1 and F2 must be moved in two directions against each other.

In 8a and 8b For example, a cylinder made of glass is used as the optical medium. By means of an actuator two lens fields or two single or two Fresnel lenses are shifted from each other. In this case, the lenses may be received separately from each other or preferably housed in a solid. As a result, a relative position is created in a basic position, for example, without a beam deflection.

at an operation of the actuator, the lens fields are shifted against each other and the beam is thereby deflected. Since the lens fields or the two single or two Fresnel lenses particularly easy in one such solid Made aligned with each other and with particularly small ways size Beam deflections can be effected, this arrangement is known usual Process superior.

1 to 4

Piezoceramic, Piezoceramic single element

10 10 ', 11

pad

20 21

pad

30 31, 40, 41

pad

 F

force

F ₁ , F ₂

lens surface

L ₁ , L ₂

lens

U _A

actuator voltage

U _M , U _M1 , U _M2

measured signal

U _S , U _S1 , U _S2

Sensor signal voltage Auxiliary excitation voltage

Z

Cylinder, which schematized an actor

Claims (39)

Single or multi-layered piezoelectric actuator which is operated by an actuator voltage applied to each layer of piezoceramic and which is simultaneously operated with at least one of the layers as a sensor for measuring the detection of the actuated by the actuator voltage forces or deformations of the piezoceramic, wherein the sensor layer / s in addition to the applied actuator voltage, a signal voltage source is connected, which emits as auxiliary excitation voltage (U _S ) a frequency-coded, a mono- or multifrequent or a frequency-variable sensor signal to the respective sensor layer / s, and wherein the sensor layer / s also a measuring circuit connected to the evaluation of the frequency response, which is based on the measurement principle "Resonator force transducer", the exploitation of the change in the material's own vibration behavior when force is based on a decoupled from the actuator voltage (U _A ) measured signal (U _M ) is obtained, which is a "response" signal containing the frequency response to the sensor signal. Piezoelectric actuator according to Claim 1, characterized in that, in the case of a series connection of a plurality of piezoelectric layers, the signal voltage source emitting the auxiliary excitation voltage (U _S ) and the measuring circuit are connected to only one layer. Piezoelectric actuator according to claim 1, characterized characterized in that Voltage level of the signal voltage source and the measuring circuit clearly are below the voltage level of the actuator voltage. Piezoelectric actuator according to one of the preceding Claims, characterized in that the Signal voltage source and the measuring circuit to the same connections the sensor layers are connected. Piezoelectric actuator according to one of claims 1 to 3, characterized in that the measuring circuit at an additional connected to the piezoceramic applied auxiliary electrode is. Piezoelectric actuator according to one of claims 1 to 3, characterized in that the measuring circuit connected to a separate, mechanically coupled piezo element is. Piezoelectric actuator according to one of the preceding claims, characterized in that the measuring circuit is decoupled from the actuator voltage (U _A ) by frequency-selective filtering. Piezoelectric actuator according to claim 1, characterized characterized in that a driven as an actuator piezoelectric layer as a sensor operated piezoelectric layer mechanically separated in series is arranged. Multilayer piezoelectric actuator according to one of Claims 1 to 7, characterized in that the signal voltage source which supplies the auxiliary excitation voltage (U _S ) is connected to the sensor layers in such a way that the individual deformations caused by the auxiliary excitation voltage cancel each other out, and the measuring circuit is connected to the sensor layers Evaluation of the frequency response is connected. Actuator according to Claim 9, characterized in that the piezoceramic layers ( 1 . 2 ) are identical in construction. Multilayer piezoelectric actuator according to claim 9 or 10, characterized in that four piezoceramic layers ( 1 . 2 . 3 . 4 mecha nisch arranged in series to form a group and that a bridge circuit formed in such a way is provided that the signal voltage source and the actuator voltage (U _A ) are completely separated by contacting different pads of the piezoceramic layers ( 6 ). Piezoelectric actuator according to one of the preceding Claims, characterized by use in a regulator circuit, for example for force control. Regulator circuit using a piezoelectric Actuator according to Claim 12, characterized in that the signal voltage source contains a sweep generator or a tunable resonant circuit. Regulator circuit according to Claim 13, characterized that the measuring circuit for evaluation of the measuring signal according to amplitude and frequency is designed so that they are more prominent the characteristic of the natural vibration behavior a comparison with the sensor signal. Regulator circuit according to Claim 14, characterized that the measuring circuit from at least one sensor signal input, at least one measurement signal input, at least one comparator for comparing the sensor signal and the measurement signal and at least one output interface for controlling the actuator voltage consists. Regulator circuit according to Claim 15, characterized that the Signal voltage source, a carrier frequency generator having one to be evaluated in a preferred manner near the Frequency carrier frequency generated, whereby a beating between sensor or measuring signal or their differential voltage signal and the voltage signal of the carrier frequency is stimulated, which is then evaluated in a different frequency range becomes. Regulator circuit according to Claim 15, characterized that in the measuring circuit another output interface for external display of the voltage or Wegmeßsignals is provided. Regulator circuit according to one of claims 13 to 17, characterized in that the the frequency and possibly amplitude modulated sensor signal forming Auxiliary excitation voltage is excited in a frequency band, in which characteristic natural frequencies of the piezoelectric actuator are. Regulator circuit according to one of claims 13 to 18, characterized in that at the evaluation of the load-dependent Natural frequency shift resorted to known methods is such. Fast Fourier Transformation (Fast Fourier Transform; FFT), the frequency-selective excitation of oscillating circuits or the evaluation of the amplitude over the frequency by a digital signal processor (DSP). Regulator circuit according to one of claims 13 to 19, characterized in that the Signal voltage source an auxiliary excitation voltage as a sensor signal in the excitation of a voltage jump, a voltage pulse or a noise signal, and that the response in the measuring circuit is evaluated. System with several piezoelectric actuators after one of the claims 1 to 12, wherein a use in the regulator circuit after a the claims 13 to 20 possible is characterized by the same number of similar serially arranged actuators in parallel branches. System according to claim 21, characterized that at a parallel arrangement of two or more piezoelectric actuators these actors are independent of each other controlled are controlled. System according to claim 22, characterized in that that at two parallel arranged similar actuators a simultaneous Extension of both actuators to parallel feed and a combination from extension of the one actor and simultaneous shortening of the another actor for one Rotation is used. System according to claim 22, characterized in that that by a combination of more than two arranged in parallel or spatially, with each other directly or via Intermediate links connected actuators actuators constructed with multiple degrees of freedom where the number of independent degrees of freedom maximum as high as the number of actuators. System according to claim 24, characterized that one Combination of six spatially Coupled actuators are provided, which is a so-called steward platform (= Hexapod) form. Application of the piezoelectric actuator after a of the preceding claims in a piezoelectric brake acting on at least one actuator as linear feed, shear or Bending reactor e.g. for controlled adjustment of the brake pads Disc brake based in the automotive or railway sector. Application of the piezoelectric actuator according to one of claims 1 to 25 in linear drives in fine positioning, eg in precision machining. Application according to claim 27, characterized by a combination of the actuator or the actuators with an electric motor and / or optionally with gears. Application according to claim 28 as a linear actuator or Turntable for Robot drives, machining centers, machine tools and the like, wherein the actuator or actuators are not used as the main drive, but serve as a supplement to brake the drive motor or at standstill self-locking to effect the drive. Application according to claim 29, characterized that the Self-locking over made a mechanically biased "safety" brake which is regulated only by energizing the actuator or the actuators to open is. Application of the piezoelectric actuator after a the claims 1 to 25 for the fine dosing of substances, in particular drugs in the clinical area or when mixing drug mixtures, e.g. in pharmacies. Application of the piezoelectric actuator after a the claims 1 to 25 in Schwingungsanregungs- and -dämpfungsanordnungen in mechanical Structures, in particular aircraft wings, helicopter rotors, in aircraft, railway or passenger car chassis, vibration-decoupled suspensions of aggregates, motors, generators and brakes, in building foundations and at railway tracks. Application of the piezoelectric actuator after a the claims 1 to 25 in injection systems, in particular those which as Gasoline or diesel injection pumps for the motor vehicle, ship, Aircraft and stationary engine area accomplished are, and at such for Applications in the chemical, power plant and plant sectors. Application of the piezoelectric actuator after a the claims 1 to 25 at valve adjustments in both the fine adjustment as also for highly dynamic Drives, such as valves in internal combustion engines, powered by a piezo stack of actuators or a piezo-bending actuator, also for the motor vehicle, ship, aircraft and stationary engine area also for Applications in the chemical, power plant and plant sectors. Application of the piezoelectric actuator after a the claims 1 to 25 in paint spraying systems, in particular for printing tasks, e.g. the color dosage and "splash" on PC black and white and color printers or for painting jobs in packaging, printing or vehicle painting. Application of the piezoelectric actuator after a the claims 1 to 25 for mirror fine adjustment in particular by one or two independent orthogonal axes, for example for optical measuring instruments, beam deflection systems, Scanners, laser processing machines, slide or similar projectors as well as measuring setups. Application of the piezoelectric actuator after a the claims 1 to 25 for the fine adjustment of a microlens array or a mirror for two-dimensional beam deflection, for example, used for the adaptive Car headlight adjustment or in the lighting technology for the building and Landscape lighting. Application of the piezoelectric actuator after a the claims 1 to 25 for beam deflection using one or more arranged in the beam path pairs plankonvexer, each with their plan area lying on one another lenses (L1, L2), wherein the lens pair or in two planes (F1, F2) lying lens pairs can be connected to a solid and each forming a pair of lenses by the actuator (Z) against each other be moved in one direction or in two directions. Actuator according to one of claims 1 to 12, characterized that he from one of the piezoceramics in terms of physical properties similar Material consists of applying an electrical voltage or an electric current corresponding to an actuator Effect leads to a deformation and the measuring principle "resonator force transducer", the exploitation the change the material inherent vibration behavior under force basis is used for measuring a sensor signal.