Piezoelectric actuator and piezoelectric actuator array

Abstract

To manufacture a piezo bending transducer for an actuator array with long service life and high performance.SOLUTION: There is provided a piezoelectric actuator 1 for performing an actuation motion 13. The piezoelectric actuator 1 includes a piezo bending transducer 2 in which the carrier layer 4 is partially covered with a piezo thin layer 3, a movable end 6, and a housing 31. A reference stopper 15 is connected to the housing 31 and determines a reference position 40 for the actuation motion 13. A first bearing area 7 includes an area of the piezoelectric actuator 1 and an area of the housing 31, which allows the piezo bending transducer 2 to twist Φ1. A second bearing area 8 has a surface 10 on the side of the bending transducer, a surface on the side of the housing, and an intermediate layer 12 between these surfaces. The intermediate layer 12 connects these surfaces, and the intermediate layer 12 can be liquefied. A pressure element 24 produces an urging torque to the piezo bending transducer 2 around the first bearing area 7 against the reference stopper 15.SELECTED DRAWING: Figure 4B

Description

Technical Field

[0001] The present invention relates to a single piezo bending transducer, and further to an array arrangement of a plurality of piezo bending transducers, so-called piezo bending transducer array, and its applications, in particular, to microvalves and microvalve arrays.

Background Art

[0002] The piezo bending transducer array according to the present invention is particularly used for operating a microfluidic valve array in a multi-channel print head or a multi-channel coating head provided with one or a plurality of rows of dispensing nozzles. These dispensing nozzles can be controlled individually or collectively and dispense droplets or liquid jets onto a surface. Applications include performing colored decoration, digitally controlling the application of liquid coating agents such as paints, varnishes, adhesives, and sealants in one or more layers with sharp contours without using spraying, and functional coating of components.

[0003] The corresponding print head may be used in the following fields. Fields where painting, sealing, and adhesion of all types of self-propelled vehicles including automobiles, aircraft, and ships are mainly performed using an industrial robot (especially a multi-axis articulated arm robot) that moves a print head or a coating head, or fields where any type of component including consumer product industry products is coated with a liquid coating agent using an industrial robot, a Cartesian robot, or a system in which such a robot is integrated into a single-pass printing system or a single-pass coating system, and all fields of coating required in relation to buildings. [[ID=Y15]]

[0004] In particular, the aforementioned microvalve array is used as a micro pneumatic pilot valve array operating on an electro-pneumatic operating principle in a print head or a coating head of the above-described type, as described in, for example, Patent Document 1. The components described herein perform the functions of the components of the micro pneumatic circuit and actuator described in Patent Document 1.

[0005] The prior art piezoelectric bending transducers discussed herein (see Figure 1, etc.) are typically actuators of a specific length, tightly fastened at one end, and designed to generate an actuation motion perpendicular to the longitudinal direction at the movable end. Such piezoelectric bending transducers are primarily composed of multiple flat material layers, each containing at least one piezoelectric layer. Applying voltage to one or more piezoelectric layers results in longitudinal expansion, causing the bending transducer to bend perpendicular to the longitudinal direction. This is a result of the internal tension in the aforementioned multilayer structure, and the deflection is significantly greater than that of longitudinal expansion. Piezoelectric bending transducers are used for actuation tasks, either directly at their first movable end or via an effector. As the length of the piezoelectric bending transducer increases, the deflection increases, the natural frequency of the first eigenmode used for actuation tasks decreases, and consequently, the force and stiffness decrease. The design goal of a piezo bending transducer is typically to maximize the deflection, force, and first natural frequency. The piezo bending transducers discussed herein are designed such that the distance between adjacent piezo bending transducers is 0.5 mm to, for example, 10 mm or more, and the stroke is on the order of 20 μm, 50 μm, 100 μm, 200 μm, or more.

[0006] For the specified operation, it is essential that the reference position of the movable end of the piezo bending transducer, or the reference position of the effector connected to this movable end, remains constant with respect to the operating element of the microvalve. The operating element of the microvalve is the movable element of the valve, for example, the closing element corresponding to the valve opening. Thus, a "valve" is formed in which the valve opening is closed or opened depending on the position of the operating element. As mentioned above, because the deflection is small for each microvalve, undesirable changes in the piezo bending transducer or in its surroundings, including the housing (such as mechanical expansion, deformation, or creep processes that can occur over time or are temperature-related) affect the reference position, i.e., the distance between the effector and the operating element of the microvalve. When the reference position changes, the function of the microvalve changes. Conventional piezo bending transducers, for example as shown in Figure 1A, are tightly fastened on one side and therefore cannot compensate for these changes over the long term.

[0007] As a solution, Patent Document 2 proposes a piezoelectric bending transducer for a pneumatic valve equipped with a "floating bearing" or a fluid bearing. A biasing torque is applied by a spring that presses the piezoelectric bending transducer to a reference position, and since the fluid bearing has no resistance when stationary, gradually occurring changes are continuously compensated. However, if a bearing fluid with high viscosity is used, fluid resistance is encountered when the operating motion is rapid. Therefore, the fluid bearing acts like a fixed bearing with respect to the aforementioned operating motion. On the other hand, a disadvantage of using a fluid bearing is that it is impossible to perform operations involving static deflection. Fluid bearings are only suitable for pulsed operations.

[0008] In addition to the requirement that the operating function remains unchanged throughout the entire service life even under the aforementioned harmful influences, the aforementioned application examples also have the following fundamental requirements: a high operating frequency, for example, within the range of 500 Hz, 1 kHz, 2 kHz, 3 kHz, 4 kHz, or 5 kHz; large deflection of the bending transducer; high holding force; low operating voltage; small difference between adjacent piezo bending transducers; a service life that is as unlimited as possible; and the ability to mass-produce piezo bending transducer arrays and microvalve arrays at low cost. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] European Patent No. 2442983(B1) [Patent Document 2] German patent number 102009033780 (B4) [Overview of the project] [Problems that the invention aims to solve]

[0010] Overall, the problem addressed by this invention is to manufacture a high-performance, long-lasting piezoelectric bending transducer for actuator arrays, specifically designed for the applications mentioned. [Means for solving the problem]

[0011] This problem is solved by a piezo actuator having the features of an independent claim. This piezo actuator comprises a piezo bending transducer and a piezo bending transducer array consisting of at least one row of piezo bending transducers.

[0012] The piezo actuator according to the present invention, including each of the disclosed embodiments, and the piezo actuator array comprising this piezo actuator enable continuous, long-term operation.

[0013] According to the presented piezo actuator alignment method, an automated alignment process of the piezo actuator relative to a reference stopper is repeatedly performed in a manner that can be repeated at any time to enable the operation of the operating element, such as the closing element of the microvalve. During the alignment process, the piezo actuator is always returned to its reference or starting position relative to the operating element, thereby eliminating the aforementioned undesirable changes in the piezo element, operating element, microvalve, or the housing region. This state remains until the next alignment process. During the alignment process, the intermediate layer within the bearing region of the piezo bending transducer is temporarily melted, and each piezo element is brought to a specified charged state. Due to an external force on the piezo bending transducer, the movable end of the piezo bending transducer, or the effector connected to this movable end, moves against the reference stopper, such as the closing element of the microvalve. Subsequently, this state is frozen by the solidification of the intermediate layer, and the piezo actuator returns to its reference position.

[0014] The alignment process according to the present invention can be used in many ways, as follows. For example, it can be used during the initial installation or startup of components, particularly when installing or starting up print heads, coating heads, dosing heads, dispensing heads, liquid valves, pneumatic valves, etc. It can also be used during maintenance work, that is, when changing components for a new application, changing or replacing peripheral components, or changing the operating conditions of an existing configuration to suit the new application or specifications. In particular, for print heads and coating heads, it can be used to adapt the head when using a different coating agent or changing the coating agent, or when adapting the head to changes in operating parameters (temperature, pressure, etc.) or coating parameters (layer thickness, coating speed, dropping frequency, changes between droplet and spray coating). Furthermore, it can be used after changing the position of a reference stopper or when the charge state of each piezoelectric element of a piezo actuator associated with a reference stopper is changed. In short, the alignment process according to the present invention can be used in any situation when setting a piezo actuator relative to new or changed conditions of any kind.

[0015] The piezo actuator according to the present invention is used to perform an operating motion and has the necessary apparatus and means to enable the aforementioned alignment process. For this purpose, the piezo actuator first has a piezo bending transducer made of a carrier layer, the carrier layer being covered on one or both sides at least partially with a piezo thin layer. Furthermore, the piezo actuator has a movable end for performing an operating motion, a housing in which the piezo bending transducer is mounted, and an operating element or operating application (such as a microvalve) securely connected thereto. The piezo actuator according to the present invention is further characterized by: a reference stopper connected to the housing and determining a reference position for the operating motion of the operating element or operating application; a first bearing region including the region of the actuator and the region of the housing, and enabling the twist Φ1 of the piezo bending transducer; a second bearing region having a surface on the side of the bending transducer, a surface on the side of the housing, and an intermediate layer between these surfaces, the intermediate layer connecting these surfaces and being liquefiable (at low temperatures). Finally, there is a pressure element for generating a biasing torque on the piezo bending transducer, resisting the reference stopper, around the first bearing region.

[0016] Accordingly, the piezo actuator according to the present invention, comprising a piezo bending transducer and a corresponding piezo bending transducer array, originally has a carrier layer according to the prior art of Patent Document 2. The carrier layer is covered on one side ("monomorphically") or on both sides ("bimorphically") by a piezo thin layer that at least partially covers the carrier layer. The piezo thin layer also has a conventional metal coating made from a thick layer or thin film structure containing, for example, silver. Furthermore, the piezo bending transducer (and the corresponding piezo bending transducer array) further has a reference stopper associated with the movable end of the piezo bending transducer, which has a movable end for performing an operating motion and defines a reference position for the operating motion, and further has a first bearing region designed to allow the piezo bending transducer to rotate about it. The piezo bending transducer also has a second bearing region having an intermediate layer between the side surface of the bending transducer and the side surface of the housing. Furthermore, the piezo bending transducer has a pressure element in the region of the first bearing area for generating a constant biasing torque to the piezo bending transducer around the first bearing area, and this pressure element is oriented so that the movable end of the piezo bending transducer or an effector connected to this movable end is pressed against an actuator or against a reference stopper associated with a microvalve.

[0017] However, in contrast to Patent Document 2, the intermediate layer in the second bearing region consists of a solid that can be temporarily melted (meltable). In a certain operating mode, the intermediate layer in the second bearing region is in a solid aggregate state, and in another preferred modification, this intermediate layer acts primarily like a fixed bearing or primarily like a rotatable bearing. Thus, with respect to one or more translational degrees of freedom, it acts like a bearing fixed at least in the direction of the operating motion of the piezo bending transducer. In this way, in contrast to Patent Document 2, static deflection during operation is also possible in this piezo bending transducer.

[0018] In the first bearing type LA1, the second bearing region, which always has an intermediate layer, supports the piezo bending transducer within a larger area, and this bearing region preferably acts firmly in all six degrees of freedom of motion (see Figure 1). In the second bearing type LA2, the second bearing region is narrowly defined or designed as a point and is located at the end of the piezo bending transducer opposite the movable end of the piezo bending transducer (see Figures 2A to 3C).

[0019] The piezo bending transducer further features an operating mode and an alignment mode. In the operating mode, the piezo bending transducer performs an operating motion, the temperature of the intermediate layer falls below its liquefaction temperature, and the intermediate layer becomes sufficiently rigid to transmit bearing forces within the second bearing region. In the alignment mode, with the temperature of the intermediate layer above its liquefaction temperature due to heat supply, the piezo bending transducer is aligned with a reference stopper.

[0020] In alignment mode, one or more alignment steps are performed, which include the following steps: liquefying the intermediate layer of the second bearing region by heating it with a heat source, or applying a voltage to all electrodes of the piezo bending transducer that should be associated with the position of a reference fastener; further, aligning the piezo bending transducer against the reference fastener under the influence of a biasing torque while the alignment time TA is sustained; and finally, solidifying the intermediate layer by cooling the second bearing region while the cooling time TK is sustained. The order of these steps is interchangeable. Therefore, in the step of solidifying the intermediate layer material, the relative positions of the bending transducer side surface and the housing side surface of the second bearing region are frozen during solidification.

[0021] Furthermore, prior to the step of solidifying the intermediate layer during the alignment time TA, which is within the range of 1 / 2 second, 1 second, 5 seconds, 10 seconds, 30 seconds, 1 minute, etc., the intermediate layer must simultaneously exist in a fluid state, and a specified voltage must be applied to all electrodes of the piezoelectric bending transducer.

[0022] Before the alignment process, if there is a deviation in the position of the piezo bending transducer with respect to its alignment with the reference stopper, the piezo bending transducer rotates in the positive or negative rotational direction about the first bearing region during the alignment time TA. While aligning the piezo bending transducer in the alignment process, the position of the bending transducer side surface of the second bearing region changes with respect to the fixed surface associated with the housing of the second bearing region, and the liquefied material can flow into the gap between the surfaces and inside and outside the intermediate layer. Finally, the relative positions of the two surfaces are frozen while solidifying, and the piezo bending transducer reaches its reference alignment state.

[0023] In order to initially bring the piezo bending transducer to the reference alignment state or place it at the reference position, the alignment process can be performed as a one-time process during the initial assembly of the piezo bending transducer. In this case, the heat of fusion required to melt the intermediate layer can be supplied, for example, by hot air or a soldering iron tip.

[0024] Also, the alignment process can be performed several times or at regular intervals, for example, on a yearly, monthly, weekly, daily, or hourly cycle, over the service life of the print head or coating head. By regularly performing the alignment process, the piezo bending transducer, that is, all the piezo bending transducers in the piezo bending transducer array, can be accurately operated in its reference alignment state for many years.

[0025] In a multi-channel print head or multi-channel coating head having one or more piezo actuators based on piezo actuators, in addition to the long-term stability obtained in this way, the differences between individual channels are minimized at the time after completion and after the initial alignment process.

[0026] In addition, in relation to this, as part of quality assurance during printing or coating operations, it is proposed to continuously detect misalignment in the printed image, or to continuously detect misalignment in the printed image by means of test printouts or test coatings, or to perform the alignment process one or more times in a timely manner. In the detection of misalignment, it is possible to display the differences between the channels of the print head or coating head. For example, specific adjustments to the printing process or coating process can be made by expanding or shrinking the operating area, or by moving the operating area of the piezo actuator. In this regard, it is particularly recommended to perform the alignment process with a changed charge state, that is, to perform the alignment process by applying a changed voltage to the electrodes of the piezo bending transducer, as compared with the most recently executed alignment process.

[0027] Therefore, it is proposed that a series of procedures for adjusting the print head or coating head to suit the application, or a series of procedures for implementing quality improvement measures, include at least one of the following steps. a) At least one of the steps of performing droplet ejection or jet ejection from the nozzles and creating a test printout or performing a test coating by the print head or coating head b) The step of measuring and certifying the test printout or test coating in a metrological, optical, or visual manner, which is performed, for example, by measuring the layer thickness, contour sharpness, glossiness, flatness of the layer to detect splashes or accompanying droplets, or by optical inspection of dynamic droplet ejection including jet velocity or droplet velocity, optical inspection of the corrosion process, and optical inspection of the detection of the deposition of the coating agent at the print head (especially the nozzle outlet) c) The step of performing the alignment process, in which each voltage applied to each electrode of the piezo bending transducer is different from the voltage at the time of the last alignment process, or the position of the reference fixture has changed compared to the position at the time of the last alignment process Furthermore, this sequence as a whole can be considered an iterative process, and preferably, even before the first step in a), the alignment step in c) is performed, and if satisfactory results are obtained, the iterative process is finally terminated after step b).

[0028] If the alignment process is repeated, it is preferable that one or more heating elements are already firmly integrated with the print head or coating head, and that these heating elements are connected to the housing and are in thermal contact with the surface of the second bearing region allocated to the housing. In this case, each heating element and each voltage applied to each electrode of each piezo bending transducer are controllable via a process controller. This process controller may be the same process controller that performs overall control of the printing or coating process, or it may be subordinate to the aforementioned process controller. Here, such control is possible by simply specifying the heat output and duration, or (preferably) by temperature control. This temperature control is preferably based on the measurement of the actual temperature near the second bearing region by a temperature sensor.

[0029] The heat output released by the heating element is preferably controlled by a process controller such that the temperature in the second bearing region rises above the melting temperature of the intermediate layer, and the intermediate layer melts within a period of time on the order of 1 second, 10 seconds, or 100 seconds.

[0030] It should be noted that the initial alignment process is performed during the initial assembly of a print head, coating head, or component comprising one or more piezo actuators according to the present invention. In this case, the intermediate layer can also be liquefied in alignment mode using an integrated heating element that is in thermal contact with the second bearing region. Alternatively, the intermediate layer can be liquefied by an external heat source such as hot air, or by bringing a soldering iron into contact with the material of the intermediate layer or one of the surfaces adjacent to the intermediate layer.

[0031] For example, the intermediate layer may preferably consist of solder with a melting point below 150°C, 200°C, or 250°C. Simultaneously, the solder can be used to electrically contact either the carrier layer of the piezo bending transducer or the electrodes of the piezo film. Alternatively, the intermediate layer may consist of a hot-melt adhesive, thermoplastic material, thermoplastic elastomer (TPE), bitumen, or wax having a melting point below 100°C, 150°C, 200°C, or 250°C. Here, it should be noted that the maximum temperature of the piezo film of the piezo bending transducer, induced by heating, should remain well below the Curie temperature of the piezo material. Therefore, generally, any material with a sufficiently low melting point is preferable for use as an intermediate layer. This is because such materials allow the intermediate layer material to melt without the induced maximum temperature of the piezo film approaching the Curie temperature of the piezo material. By using solder or a thermoplastic material as an intermediate layer, the connection is primarily made more robust, and the torsional tolerance at the connection point is directly eliminated. In this case, elastic members required within each bearing region must be added separately. In the case of thermoplastic elastomer w (TPU, TPE), the elasticity of the material allows the rotational tolerance of the corresponding second bearing region to be achieved.

[0032] Aligning the piezo bending transducer against a reference stopper is performed under the influence of a biasing torque while the alignment time TA is sustained. Accordingly, the piezo actuator according to the present invention has means for applying a biasing torque to the piezo bending transducer around the first bearing region, and as a result of the application of the biasing torque, the movable end of the piezo bending transducer or an effector connected to this movable end is pressed against the reference stopper.

[0033] The biasing torque is applied by applying a specified force F to the piezo bending transducer using a pressure element. The contact point between the pressure element and the piezo bending transducer is shifted by a lateral displacement x along the piezo bending transducer from the pivot point of the first bearing region. clamping force F of the piezo bending transducer KThe levels of force F and displacement x based on this, and the distance L of the first bearing region to the operating point of the piezo bending transducer. R The following relationship holds true for this: F*x<0.5*F K *L R The application of force structurally in this manner will be discussed using a diagrammatic embodiment.

[0034] Furthermore, the corresponding piezo bending transducer 2 of the piezo actuator according to the present invention can be constructed monomorphically by a single piezo thin layer 3 bonded to the carrier layer 4, or bimorphically by two piezo thin layers 3 bonded to both sides of the carrier layer 4. One or two piezo thin layers 3 cover the carrier layer 4, or substantially completely cover the carrier layer 4, for example, mainly within the region of the free length L1 of the piezo bending transducer.

[0035] In addition to the measures described above for ensuring, applying, and restoring certain operating conditions of the piezo actuator, the second bearing type LA2 of the piezo bending transducer in the piezo actuator according to the present invention achieves a further significant improvement in the performance of the piezo bending transducer compared to the prior art. This expands opportunities for applications with higher performance requirements or higher power density. Conversely, for the same application and the same amount of work of operation, the control voltage can be reduced, thereby significantly reducing the voltage load and mechanical tensile load on the piezo elements. This can considerably improve their long-term strength to the level of fatigue strength. Compared to the prior art, the operating performance per individual actuator or per pressure channel remains unchanged, so the width of the piezo bending transducer can be reduced, which in the case of print heads or coating heads can reduce the channel width or the distance between dispensing nozzles, or improve the print resolution.

[0036] In a preferred embodiment, the piezo actuator is characterized by: an operating point at its movable end, or an effector connected to the movable end for performing an operating motion; a centrally located and narrowly defined bearing region including the region of the actuator and housing; and a laterally located and narrowly defined bearing region at the end opposite the movable end, including the region of the actuator and housing. The aforementioned centrally located bearing region and the aforementioned laterally located bearing region have elastic members, each of which enables local rotation of the piezo bending transducer by at least + / - 2°. In this case, the centrally located bearing region is preferably located in the middle of the three sections into which the piezo bending transducer is divided.

[0037] To clarify the terminology, it should be noted that the previously mentioned bearing regions, "first bearing region" and "second bearing region," may correspond to both the "centered bearing region" and the "laterally positioned bearing region," respectively. In other words, the names "first bearing region" and "second bearing region" are based on their function and design, while the names "centered bearing region" and "laterally positioned bearing region" are based on their location.

[0038] In the second bearing type LA2, the central bearing region is preferably located in the middle of the three sections of the piezoelectric bend transducer, and the laterally located bearing region is located at the end of the piezoelectric bend transducer opposite the movable end. Both of these bearing regions are narrowly defined or designed as points, and are designed so that the rotational motion of the piezoelectric bend transducer around the bearings resulting from the deformation of the piezoelectric bend transducer is possible or tolerated without significant resistance. This bearing arrangement enables the first intrinsic mode of the piezoelectric bend transducer, as shown in Figure 3A, etc. Compared to the fixedly clamped piezoelectric bend transducer outlined in Figure 1, this is characterized by the realization of a much larger operating path (D2 in Figure 3A, not D1 in Figure 1) for a given bending radius R (same control voltage and deformation) and a given free length L1 of the piezoelectric bend transducer. In the fixedly clamped piezoelectric bend transducer, there is no rigidity, so the operating force is reduced. The fact that the operating path is much higher or larger is due to the deformation curve of the piezo bending transducer already being the twist Φ in the centrally located bearing region, which increases the end deflection D2 (see Figure 3A, etc.). Furthermore, within the region of length L2, i.e., between the centrally located bearing region and the bearing region located laterally, the piezo bending transducer deflects in the opposite direction to that in the region of free length L1 that encompasses the movable end of the piezo bending transducer.

[0039] Furthermore, a piezoelectric bending transducer mounted in this manner has a torque curve that is more uniform over its length than a typical fixed clamp, as shown in Figure 1, which generates a strong maximum load on the clamp. This is a common cause of stress-related malfunctions.

[0040] To enable the intrinsic modes of the piezoelectric bending transducer shown in Figure 3A, the centrally located bearing area (Figure 3B) and the laterally located bearing area (Figure 3C) must allow the piezoelectric bending transducer to rotate according to its deformation curve. However, the piezoelectric bending transducer must be firmly supported, at least in a direction parallel to its operating motion. For this purpose, different options for technical implementation are proposed. For example, one option is the use of a support, which is fixed to the housing and designed as a fixed, pointed or linear contact element protruding, for example, from an attachment to the housing. The piezoelectric bending transducer leans on these contact elements, which can perform tilting motion from the plane of the piezoelectric layer. In this case, especially when the operating force is high or the operating mode is extremely dynamic, the piezoelectric bending transducer must be pressed against the support with sufficient pressure to prevent it from lifting. This compressive force is applied within the corresponding bearing region, on the side of the piezo bending transducer opposite the support, by a movable spring-operated contact element such as a metal spiral spring, a bending spring, or an electrical contact spring, or by an elastomer element.

[0041] In addition to using the support in combination with a pressure element, a point-like rotatable support for the piezo bending transducer can also be realized, which is essentially done in that translational fixation is provided by each bearing region. In order to obtain the rotational motion required according to the bending line of the piezo bending transducer, it is further proposed that the bearing regions located in the center and the bearing regions located laterally have elastic members that enable rotational motion around each (possibly virtual) pivot point of each bearing region.

[0042] The elastic members can be, for example, elastic members of the piezo bending transducer within each bearing region, and can be, for example, separate elastic elements or structurally elastic regions of the carrier layer. The elastic regions are associated with each bearing region and have localized areas that are not covered by the piezo thin layer. This can be, for example, a region of the carrier layer (in the case of bearing regions located laterally) that protrudes laterally from one or two piezo thin layers. The aforementioned elastic members can also be elastic intermediate layers made of elastomer material within each bearing region. Furthermore, these elastic members can be elastic members associated with the housing, or further elastic or spring-like components connected to the housing between the housing and each bearing region. These elastic members are configured to allow rotation of the piezo bending transducer locally, at least to a small extent, within the region of each bearing region. Hereinafter, specific embodiments will be described with reference to the figures.

[0043] Regarding dimensional ratios, it should be noted that, depending on the application, the length L1 of the piezo bending transducer may be, for example, between 4mm and 6mm, between 5mm and 9mm, or between 7mm and 15mm. The length ratio L1 / L2 is preferably between 0.5 and 2. At least one piezo thin layer can cover the carrier layer mainly within the region of free length L1, or within regions L1 and L2, i.e., on both sides of each central bearing region. The latter case is significant only for the modification of the second bearing type LA2, and this case results in maximum deflection.

[0044] The corresponding piezo actuator array preferably consists of the same piezo actuator according to the present invention, equipped with the corresponding piezo bending transducer. Depending on the type of application, these piezo actuators are preferably spaced at a certain distance from each other between 0.5 mm and 1 mm, between 0.75 mm and 2 mm, or between 1.5 mm and 5 mm. The gap width (B) between adjacent piezo bending transducers is preferably between 0.05 mm and 0.2 mm, between 0.1 mm and 0.3 mm, or between 0.2 mm and 0.6 mm. Furthermore, each of the first and second bearing regions of each piezo bending transducer, or the central bearing region and each bearing region located laterally, each lies on a single line.

[0045] Furthermore, within the piezo actuator array, each contact point of each pressure element, each pivot point of each bearing region, and each operating point of each piezo bending transducer lie on a single line.

[0046] Furthermore, the piezo actuator array preferably consists of a portion that includes at least all piezo bending transducers and bearing areas, and this portion includes multiple bearing area portions related to the housing. For this purpose, it is advantageous to use connections that are elastic to torsion between adjacent piezo bending transducers of the array, for example, in their respective first bearing areas.

[0047] Furthermore, it is preferable that the above-mentioned components related to the housing in each first bearing region and each second bearing region (such as support members and pressure springs) consist of structured plates.

[0048] By definition, the term "bearing region" refers to all components related to the bearing located in the region (whether point-like, narrow, or broad) between the piezo bending transducer and a portion of the housing 31 associated with the bearing, or to components connected to the bearing that effectively contribute to the bearing's behavior (whether fixed or rotating). It should be considered that a rotating bearing may be realized within the bearing region by an elastic member that is effective for this purpose.

[0049] To avoid any doubt, the ordinal numbers used herein ("first," "second," etc.) are provided primarily (and solely) to distinguish between several similar objects, numbers, and processes, and do not necessarily define any dependencies or order between these objects, numbers, and processes. Where dependencies or order are necessary, this will be explicitly stated herein or will become apparent to those skilled in the art by examining the embodiments actually described.

[0050] The present invention and its technical environment will be described in more detail below with reference to the drawings. It should be noted that the present invention is not to be limited to the embodiments shown. Unless otherwise specified, it is also possible to extract partial features of the technical content described in the drawings and combine them with other components and findings from this specification and the drawings. In particular, the drawings and the dimensional ratios shown are approximate. The same reference numerals represent the same object, and any explanations from the descriptions of other drawings may be used as needed to supplement the description. [Brief explanation of the drawing]

[0051] [Figure 1] A schematic diagram of the piezo actuator 1 using the first bearing type LA1 is shown. [Figure 2A] This diagram shows the principle of the piezo actuator 1 using the second bearing type LA2. The first bearing region 7 is located in the center of the piezo bending transducer 2, and the second bearing region 8 is located at the immovable end 5 in the lateral direction and is designed to be narrow. [Figure 2B] This diagram shows the principle of the piezo actuator 1 using the second bearing type LA2. The second bearing region 8 is located in the center, and the first bearing region 7 is located at the immovable end 5 of the piezo bending transducer 2 in the lateral direction. [Figure 3A] This diagram shows the principle of the piezo actuator 1 using the second bearing type LA2, with an enlarged view of the special intrinsic modes of the deflected piezo bending transducer 2. [Figure 3B] This is a further enlargement of the bearing area 16 located in the center. [Figure 3C] This further expands the bearing region 17 located in the lateral direction. [Figure 4A] This is a top view of an embodiment of a piezo actuator array consisting of multiple piezo actuators 1. [Figure 4B] This shows a cross-section of an embodiment of a piezo actuator array consisting of multiple piezo actuators 1. [Figure 5] A cross-section of a further embodiment of a piezo actuator array consisting of multiple piezo actuators 1 is shown. [Figure 6A] Further embodiments of the second bearing region 8 are shown. [Figure 6B] Further embodiments of the second bearing region 8 are shown. [Modes for carrying out the invention]

[0052] Figure 1 shows a schematic diagram of a piezo actuator 1 consisting of a piezo bending transducer 2 that is deflected by D1 at the movable end 6. In this case, the movable end 6 is also an operating point 14 that contacts any actuator, preferably an operating point 14 that contacts the closing element of a microvalve. A first bearing region 7 is also shown, which is rotatable within a certain limit of + / - 5°. The first bearing region is configured as a support 9, which is the pivot point 22 of the first bearing region 7 and is also connected to the housing 31. The distance between the pivot point 22 and the operating point of the first bearing region 7 is denoted as LR. A second bearing region 8 is also shown, which extends laterally along the piezo bending transducer. The second bearing region has an intermediate layer 12 made of a liquefiable or meltable material between the surface 10 on the piezo bending transducer side and the surface 11 on the housing side of the second bearing region 8.

[0053] In this embodiment, the second bearing region 8 extends widely, so that the second bearing region 8 as a whole acts like a fixed clamp. In this case, this characteristic is referred to as the first bearing type (LA1). On the other hand, as shown in the figure, a biasing torque 34 acts permanently on the piezo bending transducer 2 around the first bearing region 7. This biasing torque 34 is generated by a downward force F acting on a contact point 23 located at a distance x from the pivot point 22 along the bending transducer of the first bearing region 7. The biasing torque 34 is made to be such that it corresponds to a small, constant moment load on the piezo bending transducer 2, which is sufficient to rotate the piezo bending transducer against the reference stopper 15 that defines the reference position 40 of the operating motion 13 of the piezo bending transducer 2 when the intermediate layer 12 is melted, i.e., when no force is acting. As described above, the intermediate layer 12 can be liquefied by melting the intermediate layer 12 in alignment mode. For example, the intermediate layer can be melted by supplying heat from an external heat source 38 in the form of hot air while it is being installed, or by using a soldering iron. As described above, the alignment process can also be performed repeatedly with several short pauses during operation by using an integrated heating element 28 that interacts with a control device and selectively controlling its temperature with a temperature sensor 37. In this case, the heating element 28 and the temperature sensor 37 are connected to the housing 31, etc., and are in close thermal contact with the second bearing region 8. A potential insulating layer 39 is located below the heating element to prevent excessive heat from flowing into the housing 31, but this is not shown herein.

[0054] Figure 2A shows a schematic diagram of the piezo actuator 1 using the second bearing type (LA2). To avoid duplication of description, the description in Figure 1 is referenced, and only the differences are discussed below. The second bearing type differs from the first bearing type (LA1) in Figure 1 in that the second bearing region 8 is spatially narrowly defined and designed to perform rotational motion to a small extent, for example, a maximum of + / - 2°. By replacing the fixed bearing in the second bearing region 8 in Figure 1 with a rotating bearing, a different bending line of the piezo bending transducer 2 is created, in contrast to Figure 1, thereby enabling the realization of a piezo actuator 1 with a much higher operating output. In Figures 1 and 2A, the first bearing region 7 corresponds to the centrally located bearing region 16 of the second bearing type (see Figures 3A and 3B), and the second bearing region 8 with the intermediate layer 12 corresponds to the laterally located bearing region 17 of the second bearing type LA2 (see Figures 3A and 3C).

[0055] Figure 2B shows a second option for implementing the second bearing type LA2. This second option differs from the option shown in Figure 2A in that the first bearing region 7 corresponds to the laterally located bearing region 17 of the second bearing type, and the second bearing region 8, which has an intermediate layer 12, corresponds to the centrally located bearing region 16 of the second bearing type LA2. To avoid duplication of description, we will refer again to the descriptions in Figures 1 and 2A and highlight only the differences.

[0056] Note that the order of the bearing regions in Figure 2B can also be applied to the first bearing type LA1. The difference between the bearing types is, again, that in bearing type LA1, the second bearing region 8 is wider and is designed as a fixed bearing.

[0057] Figure 3A shows the bend line of the piezoelectric bending transducer 2 with a second bearing type LA2. This bend line represents the first natural mode of the piezoelectric bending transducer 2 under the limit conditions of the centrally located bearing 16 and the laterally located bearing 17. Both of these bearings are resistant to local rotational deformation of the piezoelectric bending transducer 2. In this case, the total length L1 + L2 of the piezoelectric bending transducer 2 is preferably covered with a piezoelectric layer on one side (monomorphically) or on both sides. In this regard, L1 represents the free length L1 of the piezoelectric bending transducer 2, which specifies the length of the piezoelectric bending transducer 2 that is freely movable between the central bearing 16 and the movable end 6. The immovable end 5 of the piezoelectric bending transducer 2 is fixed on the laterally located bearing 17. To compare the operating path at the movable end 6 with that of the first bearing type LA1 piezo bending transducer 2 shown in Figure 1, we assume that the piezo bending transducer 2 shown in Figure 1 is constructed identically to the piezo actuator 1 shown in Figure 3A within its region L1. Therefore, both have a radius of curvature of magnitude R in the deflected state. Since the radii of curvature are the same, it can be seen that the resulting deflection D in the case of the second bearing type LA2 is considerably larger than that in the case of the first bearing type LA1.

[0058] Figures 3B and 3C show enlarged views of the deformation of the piezo bending transducer 2 shown in Figure 3A, specifically in the central bearing region 16 (Figure 3B) and the lateral bearing region 17 (Figure 3C), respectively. They show the twists Φ1 and Φ2. During operation, these twists typically move within a range of + / - 2 degrees.

[0059] Figures 4A and 4B show an example embodiment of a piezo actuator array 32, which comprises a bimorph piezo actuator 2 configured as shown in Figures 2A and 3A, mounted by a second bearing type LA2. In this case, the centrally located bearing region 16 corresponds to the first bearing region 7 shown by the dashed line in Figure 4B and comprises a support 9 as a pivot bearing. The bearing region 17 located laterally corresponds to the second bearing region 8 for performing the operating motion 13 at the movable end 6 of the piezo bending transducer 2. An effector 19 is located at the movable end 6 shown on the left, and the effector has an operating point 14 at its tip. The effector 19 is preferably connected to the piezo bending transducer 2 via an elastic connector 20, which in this case can be, for example, an elastomer intermediate piece or an elastic adhesive. The elastic connector 20 reduces the transmission of shock from the operating point 14 to the piezo bending transducer 2 and at the same time provides rotational tolerance to the effector 19.

[0060] In this embodiment, a biasing torque 34 is applied by a pressure element 24, which takes the form of a structured and optionally curved tongue-shaped pressure spring strip or array 24, located below the retaining bridge 25. The spring can have any significant shape, but is shaped to exert a force F on each individual piezo bending transducer 2 at the contact point 23. For this purpose, each of these piezo bending transducers may selectively have a separate pressure element.

[0061] For electrical contact in the piezo bending transducer 2, all piezo layers 3 must be in contact with ground (GND) on the lower side, for example, with an operating voltage VDD of 100V to 200V on the upper side. This contact is made by connecting one or more connecting electrodes 18 on the upper and lower sides. These connecting electrodes 18 extend in a direction intersecting each piezo bending transducer 2 and are provided during the manufacture of the piezo actuator array 32 by soldering or bonding under pressure, as contact strips or contact wires made of, for example, copper, brass, nickel, or a thin flexible circuit carrier material.

[0062] The second bearing region 8, including the intermediate layer 12, is located at the fixed end 5 (on the right side) of the piezo bending transducer 2. An embodiment is shown in which the carrier layer 4 is made of a solderable material such as nickel, copper, or brass. Thus, the second bearing region 8 is a region of the carrier layer 4 that is not covered by the piezo thin layer 3 and has a region that represents the elastic region 21 of the second bearing region 8. Therefore, by having a thin thickness of the carrier layer 4, for example 30 μm to 100 μm, sufficient bending elasticity is already obtained to enable the bending line shown in Figure 3A. Figure 4A shows that the carrier layer 4 is designed to be narrower in the elastic region 21. This reduces the bending force within the elastic region 21.

[0063] Accordingly, in the embodiments of Figures 4A and 4B, the surface 10 of the second bearing region 8 on the bending transducer side is the lateral surface of the carrier layer 4 of the piezo bending transducer 2, which is not covered by the piezo thin layer 3. The intermediate layer 12 is made of low-melting-point solder, and the surface 11 of the second bearing region 8 on the housing side is the contact pad 26 of the circuit board 27. This circuit board is preferably made of ceramic, as shown in Figures 4A and 4B, or of a circuit board material with a very high Tg. In this case, preferably, the heating element 28 (of a thick film) is located just below all the contact pads 26 of the piezo bending transducer 2 and separated only by an electrical insulating layer. In this configuration, the heating element is in direct thermal contact with the intermediate layer 12, so that the intermediate layer can melt within a few seconds.

[0064] Figure 5 shows an example of a cross-sectional view of an embodiment of a piezo actuator array 32, which comprises a monomorph piezo actuator 1 configured as shown in Figures 2B and 3A, and implemented with a second bearing type LA2. The monomorph piezo actuator 1 comprises a piezo bending transducer 2 having a piezo thin layer 3 at its bottom. In this case, the bearing region 16 located in the center corresponds to the second bearing region 8 shown by the dashed line, and the bearing region 17 located laterally corresponds to the first bearing region 7 shown by the dashed line. The latter is realized by firmly soldering the carrier layer 4 to the contact portion of the circuit board 27. The elasticity of this first bearing region 7 is determined by the carrier layer in region 21, as shown in Figures 4A and 4B. The second bearing region 8 is located in the center of the piezo bending transducer 2. The aforementioned second bearing region is formed by an elastic and meltable intermediate layer 12, which has good adhesion to the piezo bending transducer 2. The heating wire 28 extends in a direction intersecting all piezo bending transducers 2 within the insulating support structure, which is suitable for directly melting the intermediate layer 12 from the inside. In this configuration, the pressure element 24 for applying biasing torque 34 around the first bearing region 7 is located on the right side of the drawing and has the form of a pressure spring array 24.

[0065] Figure 6A shows a further embodiment of the second bearing region 8, in which the outermost part of the carrier layer 4 is bent and protrudes through the through-connection portion in the circuit board 27. The intermediate layer 12 corresponds to the solder in the through-connection portion. Furthermore, the heater 28 is located in a groove at the bottom of the circuit board.

[0066] Figure 6B shows a further embodiment of the second bearing region 8, which comprises a meltable elastomer or elastic adhesive as an intermediate layer 12 on the circuit board 27. This intermediate layer 12 is heated by a heating layer 28 located immediately below it and is in direct thermal contact with the heating layer 28. An insulating layer 39 between the circuit board 27 and the housing 31 is also shown.

[0067] The piezo actuator array 32 is fabricated within the panel. For example, a number of piezo layers 3, such as 16, 32, or 64, are each manufactured using a sawing process. The sawing process is performed on sawn strips, or on pre-structured bend transducer carrier layers, or on microeffectors, or a combination thereof, and is manufactured within the panel from plates of each material. That is, these form a single cohesive section. These are then joined together to the panel to form a monomorph or bimorph piezo bend transducer array 32, which is molded or bonded to the panel together with connected elastic contact electrodes, or bonded to the panel together with microeffectors. Alternatively, each piezo layer 3 and a pre-structured piezo bend transducer support structure are first bonded to each other. Then, in a second step, they are finally sawn on sawn strips within the panel for further processing within the panel.

[0068] This method includes the following steps: A manufacturing step of manufacturing one or more piezo actuator arrays 32 from a plurality of panel-type piezo bending transducers 2 according to the present invention, wherein these piezo actuator arrays are arranged side by side to form a unified structure; an insertion step of inserting the aforementioned structure into a print head or coating head; and finally, an alignment step of performing an alignment process according to the present invention, wherein all piezo actuators are aligned to their reference positions 40. This method is also characterized by the fact that no further alignment is required.

[0069] A piezo actuator 1 for performing an operating motion 13 is proposed. The piezo actuator 1 comprises a piezo bending transducer 2 consisting of a carrier layer 4, wherein one or both sides of the carrier layer 4 are covered at least partially with a piezo thin layer 3, a movable end 6, and a housing 31. The piezo actuator 1 is characterized by the following: A reference stopper 15 connected to the housing 31 and determining a reference position 40 for the operating motion 13. A first bearing region 7 including the region of the piezo actuator 1 and the region of the housing 31, which allows the twist Φ1 of the piezo bending transducer 2. A second bearing region 8 having a surface 10 on the side of the bending transducer, a surface 11 on the side of the housing, and an intermediate layer 12 between these surfaces, the intermediate layer 12 connecting these surfaces and the intermediate layer 12 being liquefiable. The pressure element 24 is for generating a biasing torque on the piezo bending transducer 2 around the first bearing region (7) against the reference stopper 15. [Explanation of Symbols]

[0070] 1. Piezo actuator (2 piezo bending transducers + 1 housing + 1 optional effector) 2. Piezoelectric bending converter 3 Piezo thin layer 4. Career Layer 5. Fixed end of the piezo bending transducer 2 6. Movable end of the piezo bending converter 2 7. First bearing region of the piezo actuator 1 8. Second bearing region of the piezo actuator 1 9 Support of the first bearing region 7 10 The surface of the second bearing region 8 on the side of the bending transducer 11 The side surface of the housing of the second bearing region 8 12 Intermediate layer of the second bearing region 8 13 Operating motion at the movable end 6 of the piezo bending transducer 2 14. Operating point in contact with the operating element 15 Standard fasteners 16. Centrally located bearing area 17 Bearing region located in the lateral direction 18 connecting electrodes 19 Effects 20 Elastic connection part 21 Elastic region of the second bearing area 22 Pivot point of the first bearing region 23. Contact point of compressive force 24 Pressure elements, pressure spring arrays 25 Retaining Bridge 26 Contact pads 27 Circuit boards 28 heating element 29 Through connection section 30 Adhesive Wires 31 Housing 32 Piezo actuator array 33. Process controller 34. Bias Torque 37 Temperature Sensor 38 External heat source 39 Insulating layer 40 Reference position D1 deflection, operating path D2 deflection, actuation path LR: Distance between the pivot point and the operating point L1 is the distance between the central bearing and the movable end of the piezo bending transducer, representing the free region. L2 Distance between the central bearing and the lateral bearings Φ1 Twist Φ2 Twist R (bending radius)

Claims

1. A piezo actuator (1) for performing an actuation movement (13), comprising: a piezoelectric bending transducer (2) consisting of a carrier layer (4), one or both sides of which are at least partially covered with a thin piezoelectric layer (3); A movable end (6); A housing (31) Equipped with A reference stop (15), connected to the housing (31); and a reference stop (15) for determining a reference position (40) for said actuation movement (13); A first bearing area (7), a region of the piezo actuator (1) and a region of the housing (31), a first bearing area (7) allowing a torsion (Φ1) of the piezoelectric bending transducer (2); A second bearing area (8), a surface (10) facing said bending transducer; a side surface (11) of the housing; an intermediate layer (12) between said surface (10) on the side of the bending transducer and said surface (11) on the side of the housing; having the intermediate layer (12) connects the surface (10) on the side of the bending transducer with the surface (11) on the side of the housing, a second bearing area, the intermediate layer (12) being liquefiable; A pressure element (24), a pressure element (24) for generating a biasing torque (34) on the piezoelectric bending transducer (2) around the first bearing area (7) relative to the reference stop (15); It is characterized by: The piezo actuator (1) is operable in an operating mode and an alignment mode; In said mode of operation, said piezoelectric bending transducer (2) performing an actuation movement (13); the temperature of the intermediate layer (12) is below its liquefaction temperature; the intermediate layer (12) being sufficiently stiff to transmit bearing forces in the second bearing region (8); In the alignment mode, The piezoelectric bending transducer (2) is aligned with the reference stop (15) while the temperature of the intermediate layer (12) is raised above its liquefaction temperature by the application of heat. A piezoelectric actuator comprising:

2. A piezo actuator (1) as claimed in claim 1, In the alignment mode, the intermediate layer (12) liquefied by an external heat source (38); or It is liquefied using an integral heating element (28) in thermal contact with the second bearing area (8). Piezo actuator.

3. A piezo actuator (1) as claimed in claim 1, so that the temperature in the second bearing region (8) rises above the melting temperature of the intermediate layer (12); The heating element (28) is controlled by a process controller; and The heat output can be calculated by the process controller; so that the intermediate layer (12) melts in a period of time on the order of 1 second, 10 seconds, or 100 seconds. The process controller calculates the heating time. Piezo actuator.

4. A piezoelectric actuator (1) according to any one of claims 1 to 3, The intermediate layer (12) is made of a solder having a melting temperature below 150°C, 200°C, or 250°C; a piezo actuator, electrically contacted by the solder either to the carrier layer (4) of the piezo bending transducer (2) or to the electrodes (18) of the piezo thin layer (3); The intermediate layer (12) is made of a thermoplastic material, a thermoplastic elastomer, bitumen, or a wax having a melting temperature below 100°C, 150°C, 200°C, or 250°C.

5. A piezo actuator (1) according to any one of claims 1 to 4, The piezoelectric actuator (1) further comprises means for applying a biasing torque (34) to the piezoelectric bending transducer (2) around the first bearing area (7), the movable end (6) of the piezoelectric bending transducer (2) or an effector (19) connected to the movable end (6) is pressed against a reference stop (15) as a result of the application of the biasing torque (34); Piezo actuator.

6. A piezo actuator (1) as claimed in claim 5, The biasing torque (34) is applied by exerting a defined force (F) on the piezoelectric bending transducer (2) by a pressure element (24), a contact point (23) of the pressure element (24) with the piezoelectric bending transducer (2) is offset from a pivot point (22) of the first bearing area (7) by a lateral offset (x) along the piezoelectric bending transducer (2); The clamping force (F Ｋ ) based on the force (F) and the level of the displacement (x) and the distance (L) of the first bearing area (7) to the operating point (14) of the piezoelectric bending transducer (2). Ｒ ) and (F)*(x)<0.5*(F Ｋ )*(L Ｒ ) holds true Piezo actuator.

7. A piezo actuator (1) according to any one of claims 1 to 6, The piezoelectric bending transducer (2) comprises: either monomorphically constructed with a single piezo thin layer (3) bonded to the carrier layer (4), or It is constructed in a bimorphic manner by two of said piezo thin layers (3) bonded on either side of said carrier layer (4), The piezo thin layer or layers (3) are - covering the carrier layer (4) mainly in the region of the free length (L1) of the piezoelectric bending transducer (2), or It substantially completely covers the carrier layer (4). A piezoelectric actuator comprising:

8. A method for aligning a piezo actuator (1) according to any one of claims 1 to 7, comprising the steps of: a) heating the intermediate layer (12) in the second bearing region (8) using a heat source to liquefy the intermediate layer; applying each voltage to be related to the position of the reference stop (15) to all electrodes of the piezo bending transducer (2); b) aligning said piezoelectric bending transducer (2) with respect to said reference stop (15) under the influence of said biasing torque (34) for the duration of an alignment time (TA); c) solidifying said intermediate layer (12) by cooling said second bearing area (8) during a cooling time (TK); Equipped with These steps are performed in the order listed above. method.

9. A method for aligning a piezoelectric actuator as claimed in claim 8, comprising: the voltages applied to all electrodes are corrected to compensate for deformation of the piezoelectric bending transducer under the applied torque; method.

10. A method for aligning a piezo actuator as claimed in claim 9, comprising: In the step of applying the voltages to the electrodes of the piezoelectric bending transducer (2), A voltage is applied that is different from the voltages applied during the most recently performed alignment step. A method comprising:

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