2-DIMENSIONALLY MOVABLE LINEAR OR ROTATIONAL TABLE

Description

[0001] The present invention relates to a 2-dimensionally movable linear or rotary table comprising a stator and at least one upper slider plate which is movable relative to the stator in two independent translational directions or two independent rotational directions, as well as at least two piezoelectric linear drives for moving the upper slider plate in the two translational directions or two rotational directions.

[0002] Such 2-dimensionally movable linear, rotary, or tilting tables are simple and precise positioning and handling systems that are used not only in research and development, but also in industrial processing and production. Applications range from industrial conveyor systems for the precise alignment of transported products for subsequent product recognition, labeling, marking, and packaging to the high-precision positioning of fixtures or samples in research and development. Above all, such linear, rotary, or tilting tables are characterized by precise movement with low friction and deformation-free absorption of lateral forces.The use of piezoelectric linear drives enables the movement of the slider plate without mechanical transmission of the drive, thereby achieving a fast response speed as well as high rigidity and dynamics of the drive. Due to the linear direction of movement of such piezoelectric linear drives, i.e. the back and forth movement along a spatial axis, at least two piezoelectric linear drives are required to position the slider plate in two independent translational or two independent rotational directions. The movement of the upper slider plate in two independent translational or two independent rotational directions refers to the directions of movement of a rigid body in space in the direction of the six possible degrees of freedom, i.e. in three independent translational directions and three independent rotational directions around three independent axes, in each case back and forth.

[0003] To move linear or rotary tables in two independent translational or two independent rotational directions, the tables are divided into multiple planes, and the layers are arranged one above the other. Typically, a 2-dimensionally movable linear or rotary table has three layers: the upper layer is the upper slider plate on which the products or elements to be transported are arranged. The middle layer is a combination of a stator of the upper movement plane and a slider of the lower movement plane. The linear drive of the upper movement plane is positioned on this middle layer. Finally, the lower layer forms the base plate or stator of the lower movement plane.When a piezoelectric linear actuator mounted on the base plate in the lower movement plane moves the slider plate of the middle layer in an independent direction, the second piezoelectric linear actuator mounted on top of the middle slider plate and the upper slider plate, which is moved by the second piezoelectric linear actuator in a second independent direction, also move with this middle slider plate. The connecting cables supplying the second linear actuator must also move along with the second piezoelectric linear actuator mounted on the middle slider plate.Especially in applications requiring very high precision for the exact positioning of elements in the nanometer range, very high linearity of the upper slider plate's movement, and high long-term stability of the positioning accuracy and linearity of movement, the connecting cable for the second piezoelectric linear drive can disrupt the movement of the middle slider plate in the lower movement plane, particularly depending on the stiffness of the connecting cable. Therefore, for linear and rotary tables with high requirements for positioning accuracy and stable linearity of movement, conductive strips are used to connect the second piezoelectric linear drive. These strips have almost negligible stiffness in the direction of movement of the lower movement plane.JP H 7-226354 A discloses a generic positioning device for semiconductor manufacturing that enables precise positioning of an XY stage, even when the temperature distribution of an optical path changes and the ambient pressure fluctuates. EP 938 144 A2, on the other hand, discloses a printer support plate with an ultrasonic motor, a first movable body, and a second movable body that moves in one direction together with the first body and in another direction independently of the first body, as well as a piezoelectric actuator or ultrasonic motor connected to the first body. The paper entitled "Review on Multi-Degree-of-Freedom Piezoelectric Motion Stage" by LIU YINGXIANG et al., in IEEE ACCESS, Vol. 6, published on October 5, 2018, pages 59986-60004, DOI: 10.1109 / ACCESS.2018.US 2875940 discloses a research report on piezoelectrically driven motion stages with multiple degrees of freedom used for high-precision movements over a wide travel range. In addition to the main components and their functionality, the operating principles of the various drive types, design schemes, and structures of the piezoelectric motion stages are also described. US 2013 / 222899 A1 discloses a sample stage for a tissue sample with a curved surface window, a carriage with a tissue sample container on which the window is mounted, and a platform supporting the carriage. The carriage is mounted on the platform along two rotational axes so that the movement of the carriage follows the curvature of the window.

[0004] The present invention is therefore based on the object of providing a 2-dimensionally movable linear or rotary table with the highest positioning accuracy and outstanding movement linearity.

[0005] This object is achieved according to the present invention in that a middle rotor plate is provided, wherein the middle rotor plate is arranged between the stator and the upper rotor plate, and in that the at least two piezoelectric linear drives, which each move the upper rotor plate in one of the two independent translational or two independent rotational directions, are each fastened to the stator in order to move the upper rotor plate in the two translational or rotational directions, and wherein at least one piezoelectric linear drive fastened to the stator is in contact with the upper rotor plate through an opening in the middle rotor plate in order to move the upper rotor plate in a first translational or rotational direction. These at least two piezoelectric linear drives are independent of one another and designed as completely separate linear drives.The arrangement of all piezoelectric linear drives for the 2-dimensional movement of the upper slider plate on the base plate or the stator of the linear or rotary table makes it possible to dispense with a movable connecting cable for the second linear drive and thus avoids even the slightest influence on the positioning and movement linearity of the upper slider plate.

[0006] The provision of a central runner plate and its arrangement in a plane of movement between the stator and the upper runner plate enables a structurally simple design of a linear or rotary table according to the invention. The central runner plate and the upper runner plate are arranged such that they move together in a second translational or rotational direction relative to the stator, and the upper runner plate moves relative to the central runner plate only in the first translational or rotational direction.For this purpose, a second piezoelectric linear drive attached to the stator can either be in contact with the middle rotor plate in order to move the middle rotor plate directly and the upper rotor plate indirectly in the second translational or rotational direction, or alternatively can be in direct contact with the upper rotor plate through the opening in the middle rotor plate in order to move the upper rotor plate directly and the middle rotor plate indirectly in the second translational or rotational direction.

[0007] Although the at least two piezoelectric linear drives can each only move in one linear direction, the inventive design enables two-dimensionally movable linear or rotary tables with sub-nanometer positioning accuracy and maximum motion linearity with good long-term stability. The two piezoelectric linear drives are preferably arranged resiliently relative to the slider plate to ensure reliable transmission of movement in the two independent translational or rotational directions to the upper slider plate.

[0008] Conveniently, the at least two piezoelectric linear drives attached to the stator are arranged at an angle to one another, preferably at an angle of 90° to one another. The arrangement of the at least two piezoelectric linear drives at an angle to one another, with the orientation of the arrangement of the piezoelectric linear drives on the stator corresponding to the direction of movement of the linear drives, in particular the axes of the two independent translational directions or perpendicular to the axes of the two independent rotational directions, enables a secure, slip-free transmission of the movement of the piezoelectric linear drives arranged on the stator to the upper rotor plate.

[0009] A preferred embodiment provides for a guide for the upper slider plate to guide the upper slider plate relative to the stator in at least one, preferably two, translational or rotational directions. Such guidance of the upper slider plate in the direction of movement of the upper slider plate enables precise positioning and linear motion of the upper slider plate while simultaneously ensuring high stability of the two-dimensionally movable linear or rotary table.

[0010] A useful embodiment provides for a guide between the stator and the middle runner plate, and between the middle runner plate and the upper runner plate, to guide the upper runner plate relative to the stator in at least two independent translational or rotational directions. Such a guide in the direction of the two independent translational or rotational directions of movement of the middle runner plate or the upper runner plate ensures precise positioning and alignment of the upper runner plate and improves the stability of the linear or rotary table according to the invention.

[0011] A favorable variant provides for the guides between the stator and the middle rotor plate and / or the guide between the middle rotor plate and the upper rotor plate to be designed as guide rails, with the guide rails preferably being provided on two opposite sides of the stator and / or the middle rotor plate or the middle rotor plate and / or the upper rotor plate. This enables a particularly rigid construction and thus consistently high positioning and repeatability accuracy even with higher dynamics and fast response speeds.

[0012] Furthermore, it is advantageous if the upper rotor plate and / or the middle rotor plate have a resilient force-absorbing device for absorbing a driving force of the piezoelectric linear drives. Such a resilient force-absorbing device enables easy maintenance and replacement of the force-absorbing device without dismantling the at least two piezoelectric linear drives attached to the stator. Furthermore, such a resilient force-absorbing device enables the targeted adjustment of static friction between the piezoelectric linear drive and the upper rotor plate and / or the middle rotor plate.

[0013] A useful embodiment provides for the at least two piezoelectric linear drives to be configured as at least two piezoelectric friction contact drives. Friction contact drives allow secure movement of the middle runner plate and the upper runner plate in two translational or rotational directions. The at least two piezoelectric friction contact drives can each have at least one drive element configured as a friction element, wherein the friction elements are in frictional contact with the upper runner plate or with the middle runner plate and the upper runner plate in order to move the upper runner plate in two translational directions or two rotational directions.Such friction elements can be easily pressed onto the upper slider plate or the upper and middle slider plates to enable secure movement of the middle slider plate and the upper slider plate in two translational or rotational directions using a simple construction. Furthermore, such friction contact drives have the advantage that, when de-energized, they maintain the current position of the corresponding slider plate due to the existing friction contact with the plate, thus acting as a self-locking mechanism.

[0014] A particular embodiment provides that the at least two piezoelectric linear drives are designed as at least two encapsulated piezoelectric linear drives, and in particular as encapsulated piezoelectric inertial or resonant drives. Such encapsulated piezoelectric linear drives enable protection of the actual actuators, which comprise an electromechanical material and are deformed by an electrical control to generate a linear movement of the drive, from environmental influences within the linear or rotary table according to the invention. In particular, the sensitive contact points between the electrodes of the piezoelectric linear drives and the actual actuators are not contaminated by moisture, dust, abrasion, or lubricants.As a result, there is significantly less wear and tear at these contact points, which significantly increases the service life of the piezoelectric linear drives and thus of the linear and rotary tables.

[0015] Advantageously, the encapsulated piezoelectric linear drives can comprise a housing, at least two actuators arranged within the housing and comprising an electromechanical material, each of which generates a deflection when excited by an electrical control voltage, and a drive element arranged outside the housing. An elastic wall section of the housing, which is elastically deformed by the deflection of the actuators, couples the actuators and the drive element to one another in such a way that the drive element is set in motion by the deflection of the actuators. The elastic wall section of the housing is elastically deformed by the deflection of the actuators.The elastic wall section, which can be designed as a membrane, for example, allows the protective function of the housing to be fully maintained, while at the same time transmitting the deflection generated by the actuators directly to the drive element of the encapsulated piezoelectric linear drive located outside the housing. It is advantageous if the drive element is resiliently preloaded relative to the actuators with the elastic wall section of the housing interposed. This resilient preload holds both the actuators and the drive element in close and direct contact with the elastic wall section. The force is thus transmitted indirectly between the actuators and the drive element, yet directly, and largely eliminates disruptive influences.

[0016] A useful embodiment provides for the housing to consist of two or more housing parts, wherein the housing parts are preferably connected to one another with the interposition of at least one sealing element, in particular are connected to one another hermetically, wherein the sealing element is preferably made of epoxy resin, an adhesive, or a rubber-elastic material. This allows the various housing parts to be connected or separated as needed during installation and removal of the actuators in or from the housing. When the housing is closed, the actuators are non-positively fixed in the housing, preferably clamped between the interconnected housing parts.

[0017] A preferred embodiment provides that a first housing part is designed as a preferably flat plate and a second housing part as an open hollow body that can be closed by the flat plate and has a cavity for receiving the actuators, wherein the open hollow body preferably comprises the elastic wall section, which is aligned parallel to the first housing part when the housing is enclosed. This allows the two housing parts to be optimally sealed to one another, in particular by means of a simple sealing ring. Furthermore, the flat plate is excellently suited for attaching or integrating flat cable structures, while the open hollow body in itself has its own spatial stability and forms a corresponding mechanical protective function for the actuators. This also applies in particular to the elastic wall section, which is expediently designed as part of the hollow body.In addition, a heat sink can also be provided in such a construction, for example as part of the flat plate, in order to safely dissipate the waste heat generated when the actuators are deflected from the housing.

[0018] A further embodiment provides that the encapsulated piezoelectric linear actuators have an electrical conductor structure with connection points on the inside of the housing and connection points on the outside of the housing, which are connected by conductor tracks. The actuators are electrically connected to the connection points on the inside of the housing, preferably by electrically conductive adhesive, with the connection points on the outside of the housing preferably being designed for permanent connection to a control device for controlling the actuators. Alternatively, the connection to a control device can also be connected to a busbar using a flexible printed circuit board or electrically conductive pins for a sliding contact. The electrical conductor structure can be machined, for example by etching, from an electrically conductive film that was previously applied to a housing plate.Such conductor structures are very flat and can extend through a sealing layer on a hermetically sealed surface. A flat plate with such an applied electrical conductor structure is particularly suitable as a first housing part, whereby the actuators mounted on such a circuit board can be covered by an open hollow body with an elastic membrane designed as the second housing part.

[0019] It may be advantageous if the connection points on the inside of the housing and the connection points on the outside of the housing, and possibly the conductor tracks, extend in the same plane, preferably on a side of the first housing part facing the second housing part. It is useful if the conductor structure is firmly connected to the housing, in particular to the first housing part, since this design avoids protruding conductor wires or connection points, which are difficult to accommodate in confined spaces.

[0020] A practical variant provides for the encapsulated piezoelectric linear drives to have a support and a spring device that urges the housing against the support, with the drive element preferably being arranged on the spring device. In this form of linear or rotary table according to the invention, the actuators accommodated by the housing of the piezoelectric linear drives and the drive element of the piezoelectric linear drives driven by the actuators are securely positioned relative to one another.

[0021] The support and the spring device can expediently form a frame enclosing the housing, with the spring device preferably being designed as a spring element spanning the housing. The spring element can be connected to the support on one or both sides of the housing. This special design and arrangement of a spring element enables a particularly compact and stable design of a piezoelectric linear drive for a linear or rotary table.

[0022] Furthermore, the present invention relates to a method for moving a 2-dimensionally movable linear or rotary table, preferably according to one of the previously described embodiments.The linear or rotary table comprises a stator, at least one upper slider plate which moves relative to the stator in two independent translational directions or two independent rotational directions, a middle slider plate which is arranged between the stator and the upper slider plate, and at least two, preferably four, piezoelectric linear drives fastened to the stator in order to move the upper slider plate in the two translational directions or two rotational directions, wherein at least one piezoelectric linear drive fastened to the stator is in contact with the upper slider plate through an opening in the middle slider plate and moves the upper slider plate in a first translational direction or a first rotational direction, and wherein for moving the upper slider plate in one or both independent translational directions orIn one or both independent rotational directions, the individual motion contributions of all piezoelectric linear drives attached to the stator are added or subtracted according to the signs of the motion contributions. Such a method enables a reliable, slip-free transmission of the individual motion contributions of the piezoelectric linear drives arranged on the stator to the upper rotor plate. It is particularly preferred that two piezoelectric linear drives attached to the stator are in contact with the upper rotor plate through the opening in the middle rotor plate in order to move it in a first translational direction or a first rotational direction.

[0023] It may be advantageous if the at least two, preferably four, piezoelectric linear drives attached to the stator are inclined at an angle, preferably at an angle of 45°, to the two translational directions or to the projections of the two rotational directions into the stator plane, wherein all piezoelectric linear drives attached to the stator provide a substantial positive or negative movement contribution for moving the upper rotor plate in one of the independent translational directions or in one of the independent rotational directions.By electrically exciting all piezoelectric linear actuators to move the upper slider plate in only one translational or rotational direction, the frictional inhibition that otherwise occurs during start-up and movement between the drive element of a non-actuated piezoelectric linear actuator and the upper slider plate can be prevented or at least significantly reduced.

[0024] Alternatively, in a method for moving a 2-dimensionally movable linear or rotary table, in which the at least two, preferably four, piezoelectric linear drives attached to the stator are arranged parallel to the two translational directions or to the projections of the two rotational directions into the stator plane, and in which at least one piezoelectric linear drive, which does not provide any movement contribution for moving the upper rotor plate in exclusively one of the independent translational directions or in exclusively one of the independent rotational directions, the at least two actuators of this at least one piezoelectric linear drive can be supplied with an identical voltage signal, preferably a sinusoidal or sawtooth-shaped voltage signal, iewith an in-phase control of the two opposing actuators, in order to reduce the frictional inhibition occurring between the drive element of this one piezoelectric linear actuator and the upper rotor plate during starting and during movement.

[0025] In the following, non-limiting embodiments of the invention are explained in detail with reference to exemplary drawings. They show: Fig. 1 shows a perspective exploded view of various components of a drive device of a piezoelectric linear drive for a linear or rotary table according to the invention, Fig. 2 shows perspective views of an assembly of the drive device from Fig. 1, wherein the actuators of the drive device are arranged on a flat housing plate provided with a conductive structure, wherein view (a) shows the assembly from a first side and view (b) shows the assembly from a second side, Fig. 3 perspective views of the drive device from Fig. 1 , wherein the actuators are accommodated in the housing, wherein view (a) shows a perspective sectional view of the assembly and view (b) shows a perspective side view of the assembly including a connected flexible printed circuit board, Fig. 4 shows a perspective exploded view of a piezoelectric linear actuator with the drive device of Fig. 1 , Fig. 5perspective views of the piezoelectric linear actuator from Fig. 4in an assembled state, wherein view (a) shows a perspective side view of the piezoelectric linear drive and view (b) shows a perspective sectional view of the piezoelectric linear drive from a similar viewing direction, Fig. 6 shows various sectional views of a conventional 2-dimensionally movable linear stage, wherein view (a) shows a perspective sectional view and view (b) shows a front sectional view, each in a sectional plane arranged perpendicular to a translational direction of movement, Fig. 7 shows a perspective exploded view of a second piezoelectric linear drive for a linear or rotary stage according to the invention with a different spring element, Fig. 8 shows perspective views of the piezoelectric linear drive from Fig. 7in an assembled state, wherein view (a) shows a perspective external view of the linear drive and view (b) shows a perspective sectional view of the linear drive, each from a similar viewing direction, Fig. 9 a perspective view of a conventional linear or rotary table with the piezoelectric linear drive from Fig. 8 , where view (a) shows the linear table and view (b) the piezoelectric linear drive from Fig. 8 Fig. 10 shows a perspective side view of the linear table from Fig. 9 in an assembled state, Fig. 11 a perspective view of a first embodiment of a 2-dimensionally movable linear or rotary table according to the invention with a piezoelectric linear drive according to Fig. 8 , Fig. 12 an exploded perspective view of the linear or rotary table from Fig. 11 , Fig. 13 a second perspective exploded view of the linear or rotary table from Fig. 11, Fig. 14 a perspective view of a second embodiment of a 2-dimensionally movable linear or rotary table according to the invention, Fig. 15 a perspective exploded view of the linear or rotary table from Fig. 14 . Fig. 16 a top view of the linear or rotary table from Fig. 14 without upper slide plate, Fig. 17 a perspective exploded view of a second variant of the linear or rotary table according to the invention from Fig. 14 , Fig. 18 a top view of the second variant of the linear or rotary table from Fig. 17 without upper and middle slide plates, Fig. 19 a perspective exploded view of a third variant of the linear or rotary table according to the invention from Fig. 14 , Fig. 20 a top view of the third variant of the linear or rotary table from Fig. 19without upper slide plate, Fig. 21 a perspective view of a third embodiment of a 2-dimensionally movable linear or rotary table according to the invention, Fig. 22 a perspective exploded view of the linear or rotary table from Fig. 21 , Fig. 23 a partially cutaway perspective view of the linear or rotary table from Fig. 21 , Fig. 24 a perspective view of the upper slide plate of the linear or rotary table from Fig. 21 , Fig. 25 a perspective view of a fourth embodiment of a 2-dimensionally movable linear or rotary table according to the invention, Fig. 26 a perspective exploded view of the linear or rotary table from Fig. 25 , Fig. 27 a partially cutaway perspective view of the linear or rotary table from Fig. 25 , Fig. 28 a perspective view of the upper slide plate of the linear or rotary table from Fig. 25 ,

[0026] In the Figures 1 to 10 Various encapsulated piezoelectric linear drives and their use in conventional linear or rotary tables are described, whereby these encapsulated piezoelectric linear drives are preferably also used in the various embodiments of the 2-dimensionally movable linear or rotary tables according to the invention in order to enable robust operation with high positional accuracy and stability independent of the ambient conditions, despite an open structure across the movement planes of these linear or rotary tables according to the invention. As in Fig. 1As can be seen, such piezoelectric linear drives 1 comprise identical electromechanical actuators 3, which are approximately cube-shaped and consist of a plurality of alternately arranged piezoelectric layers and layer electrodes (so-called multilayer structure). The layer electrodes between the piezoelectric layers are alternately connected to side electrodes 3b, 3c of different polarity, which are arranged on the front and rear end faces of the actuators 3. However, it is also conceivable to use actuators that have electrodes only on their top and bottom sides or on two opposite sides and thus do not have internal electrodes as in a multilayer structure. With such actuators, however, higher electrical voltages are necessary for their control.

[0027] The actuators 3 are arranged mirror-symmetrically next to one another in a hermetically sealed housing 2 and can be supplied with electrical control voltages from outside the housing 2 via a conductor structure 6. The housing 2 comprises a flat, essentially rectangular plate as the housing lower part 2a, on the upper side of which is the conductor structure 6 for the electrical connection of the actuators 3. This conductor structure 6 comprises connection points 6a on the inside of the housing for the side electrodes 3b, 3c of the actuators 3 as well as connection points 6b on the outside of the housing. The connection points 6b provided on the outside of the housing 2 and the connection points 6a on the inside of the housing are connected to one another via intermediate conductor tracks 6c. In the present case, the housing upper part 2b is designed as an open hollow body in the form of a cuboid cover. This housing cover defines a receptacle or cavity for the two actuators 3.A circumferential sealing ring 7 is located between the lower housing part 2a and the upper housing part 2b. Instead of a physical sealing ring 7, the two housing parts 2a, 2b can also be connected and sealed using a hardening adhesive. In the assembled state, which is described below with reference to the . Figures 3 to 5 As explained, the lower housing part 2a and the upper housing part 2b are pressed against each other by clamping the sealing ring 7, as shown in Fig. 3a and 3b shown, so that the housing 2 is hermetically sealed. Since the housing division between the lower housing part 2a and the upper housing part 2b lies exactly in one plane, a particularly simple sealing of the housing 2 can be achieved here.

[0028] On the closed top of the housing upper part 2b there is an elastic membrane 2c, which, as in Fig. 3ashown, in the assembled state of the housing 2 is in contact with the upper side 3a of the actuators 3. The elastic membrane 3c is deformed by the actuators 3 when electrically actuated. In the assembled state, the housing 2 has an approximately cuboidal outline, with the connection points 6b on the outside of the housing protruding laterally from the housing 2 in the plane of the housing base 2a. At these connection points 6b on the outside of the housing, as shown in Fig. 3b As shown, a flexible printed circuit board 8 can be connected or connected to a fixed terminal. Such a flexible printed circuit board 8 has a conductor structure communicating with the conductor structure 6 on the housing base 2a in order to apply an electrical control voltage to the actuators 3.

[0029] Fig. 4shows an exploded view of the piezoelectric linear drive 1, comprising the drive unit consisting of the housing 2 and the actuators 3, a bearing structure 5 designed as a frame and the flexible printed circuit board 8. The bearing structure 5 designed as a frame in the present case consists of an approximately C-shaped support 5a, which has a longer central leg and two shorter side legs. The central leg of the support 5a forms a support for the drive unit. The shorter side legs of the support 5a have openings on the upper side, i.e. on the side facing away from the central leg, to which openings a spring element 5b provided with a drive element 4 in the form of a flat sheet metal strip can be screwed by means of screw bolts. In the assembled state, the housing 2 is clamped between the support 5a and the spring element 5b.The drive element 4 is a hemispherical friction nose, which rests with its flat side centrally on the upper side of the spring element 5b and with its hemispherical outer surface facing away from this spring element 5b. To increase the strength of the arrangement, the housing 2 can additionally be glued to the carrier 5a and / or to the spring element 5b.

[0030] The bearing structure 5 is dimensioned such that in the assembled state of the piezoelectric linear drive 1 the spring element 5b rests exactly on the elastic membrane 2c of the housing 2, as clearly shown in the Figures 5a and 5bis shown. When the actuators 3 are electrically controlled, the deflection of the actuators 3 along the lines A is first transmitted to the elastic membrane 2c, and from there to the spring element 5b, which is spring-loaded relative to the membrane 2c, in order to set the drive element 4 in motion along the line B in a linear direction (back and forth). Depending on the control of the actuators 3, different movement patterns of the drive element 4 can be represented. In one operating mode of the piezoelectric linear drive 1, the actuators 3 can be controlled, for example, in such a way that the drive element 4 drives a component to be driven, which is coupled to it, in one direction along the line B using the stick-slip effect. In another operating mode of the piezoelectric linear drive 1, the drive element 4 drives the component to be driven in an opposite direction along the line B.In these operating modes, one of the actuators 3 is expanded along line A due to the electrical control, and the other of the actuators 3 is contracted along line A. Due to the electrically induced deformations of the actuators 3, the drive element 4 tilts along line B towards one end of the carrier 5a in the direction of the contracted actuator 3. In the drive direction of the element to be driven along line B, the movement of the drive element 4 is slower than in the opposite direction, so that in the sticking phase, the drive element 4 drives the element to be driven in the drive direction via static friction, and in the sliding phase, due to the inertia of the element to be driven, it slides along the element to be driven in the opposite direction.The stick-slip effect as well as the function and mode of operation of corresponding piezoelectric linear actuators 1 are basically known and will therefore not be explained in more detail.

[0031] In a known arrangement, such a piezoelectric linear drive 1 can be used in a conventional linear or rotary table 10. The piezoelectric linear drive 1, as shown in Fig. 6a and 6b shown, mounted on a stator 11 such that the drive direction B is aligned parallel to a guide direction F of the rotor 12 predetermined by a linear guide 13. A position encoder 14 and a position sensor 15 determine the position of the rotor 12 relative to the stator 11. This information is used to control the actuators 3 of the piezoelectric linear drive 1 in order to regulate the position of the rotor 12 relative to the stator 11.

[0032] According to the presentation in Fig. 6b The rotor 12 is resiliently preloaded relative to the stator 11 or relative to the drive element 4 of the piezoelectric linear drive 1. For this purpose, a projecting spring plate 16 is located on the underside of the rotor 12, which is screwed to the rotor 12 at one end and is in contact with the drive element 4 of the piezoelectric linear drive 1 with its free end. This spring plate 16 enables the rotor 12 to particularly well absorb the drive forces of the piezoelectric linear drive 1 exerted by the drive element 4.

[0033] The second embodiment, which is described below with reference to the Figs. 7 to 10 is essentially based on the first embodiment and comprises largely identical features. To avoid repetition, these identical features are provided with identical reference numerals in the figures. For the explanation of these reference numerals, reference is made to the first embodiment in the Figs. 1 to 6 The essential differences from the first embodiment are described in detail below.

[0034] In the Figs. 7 to 10A further embodiment of the encapsulated piezoelectric linear drive 1 is shown. Deviating from the previously described embodiment, the spring element 5b of the bearing structure 5 of the piezoelectric linear drive 1 comprises a different configuration. This spring element 5b of the bearing structure 5 is not only formed as a sheet metal strip with approximately the same width as the support 5a, but also protrudes significantly beyond the support 5a on one side. On this protruding side of the spring element 5b, the piezoelectric linear drive 1 is resiliently mounted on the stator 11 of the linear drive 10. To increase stability and spring action, a corresponding spring element 5c can be provided on the underside of the support 5a, corresponding to the spring element 5b on the top side of the support 5a, as shown in the illustration of a conventional linear or rotary table 10 in the Figures 9 and 10can be seen. By means of material recesses and incisions, the weight of such spring elements 5b, 5c can be minimized in applications based on the findings of lightweight construction technology while maintaining almost unchanged stability.

[0035] In contrast to the first embodiment, the spring element 5b of the piezoelectric linear drive 1 not only generates a resilient preload of the drive element 4 relative to the actuators 3, but also a resilient preload of the drive element 4 relative to the rotor 12. Consequently, this arrangement improves both the force transmission between the actuators 3 and the drive element 4, as well as the force transmission between the drive element 4 and the rotor 12.

[0036] The principle of an encapsulated piezoelectric linear drive 1, in particular a piezoelectric inertial or resonance drive, in which at least two actuators 3 (e.g. piezoelectric multilayer actuators 3) are arranged in a housing 2 on a base plate 2a, and a friction-coupled drive element 4 is arranged on the top of this housing 2, protects the actuators 3 from the dust-like abrasion generated during sliding contact between the rotor 12 and stator 11 of a 2-dimensionally movable linear or rotary table, as well as from lubricant that may be used in the linear or rotary guides. The special feature of these encapsulated piezoelectric linear drives 1 is that the force transmission between the actuators 3 and the friction-coupled drive element 4 is not impaired by the encapsulation of the actuators 3 in the housing 2.Another secondary function of the housing 2 is to dissipate heat generated by the actuators 3 during operation to the environment. The housing 2 can effectively protect the piezoelectric layers and layer electrodes, as well as the connection electrodes 6a of the actuators 3 inside the housing, from oxidation. The insulation of the contact points of the actuators 3 and electrodes from the environment prevents dust- or moisture-induced oxidation, even under demanding environmental conditions. The insulation of the actuators 3 thus provides a significant advantage for reliable operation and a long service life of the piezoelectric linear drive 1.

[0037] The Figs. 11 to 28show various embodiments of 2-dimensionally movable linear or rotary tables 20 according to the invention. Such 2-dimensionally movable linear or rotary tables 20 essentially consist of three layers: a stator 21 acting as the lower layer or base plate, a middle slider plate 22, and an upper slider plate 23, which are each arranged one above the other and define two planes of movement between them in order to move the upper slider plate 22 in relation to the stator 21 in two independent translational directions of movement T1, T2 or two independent rotational directions of movement R1, R2. In this case, only the upper slider plate 23 moves in both independent translational directions of movement T1, T2 or rotational directions of movement R1, R2.For each of the two independent translational directions of movement T1, T2 or two independent rotational directions of movement R1, R2, at least one piezoelectric linear drive 1 is provided, which is fastened to the stator 21 with its frame 5 or frame lower part 5a, while the drive elements 4 of the piezoelectric linear drives 1 act on the middle rotor plate 22 or the upper rotor plate 22 in order to move the upper rotor plate 22 relative to the stator 21 in the two independent translational directions of movement T1, T2 or two independent rotational directions of movement R1, R2.Since the supports 5 of the piezoelectric linear drives 1 are firmly connected to the stator 21 of the 2-dimensionally movable linear or rotary table 20, the connecting cables of the piezoelectric linear drives 1 can be laid permanently, so that in an embodiment of the linear or rotary table 20 according to the invention, a flexible connecting cable for the piezoelectric linear drives 1 for moving the upper rotor plate 23 can be completely dispensed with.

[0038] The perspective view in Fig. 11 shows a 2-dimensionally movable linear table 20 according to the invention. As can be seen from the exploded drawings in Figs. 12 and 13As can be clearly seen, this two-dimensionally movable linear table 20 comprises a stator 21 on which three piezoelectric linear drives 1 are arranged, as well as a middle slider plate 22 and an upper slider plate 23. The piezoelectric linear drives 1 are each firmly mounted on the stator 21 with their frame 5, while the drive element 4 acts on the middle slider plate 22 or the upper slider plate 23 to move the upper slider plate 23 in two independent translational directions of movement T1, T2. The two piezoelectric linear drives 1 arranged on the outer end faces of the stator 21 act on the sides of the middle slider plate 22 to move the middle slider plate 22 in a first translational direction of movement T1.The piezoelectric linear drive 1 arranged in the middle of the stator 21 acts with its drive element 4 through an opening 24 in the middle rotor plate 22 directly onto the upper rotor plate 23 in order to move the upper rotor plate 23 in a second translational direction of movement T2 independently of the movement or position of the middle rotor plate 22.

[0039] When the upper rotor plate 23 moves via the electrically excited piezoelectric linear drive 1 arranged centrally on the stator 21, the middle rotor plate 22 is held in its position in the first translational direction of movement T1 by the two laterally arranged piezoelectric linear drives 1, provided these two piezoelectric linear drives 1 are not electrically excited. In a case in which all piezoelectric linear drives 1 attached to the stator 21 are electrically excited, the upper rotor plate 23 moves simultaneously in the two independent translational directions of movement T1, T2.When the two laterally arranged piezoelectric linear drives 1 are exclusively controlled to move the middle rotor plate 22 only along the first translational direction of movement T1, this movement of the middle rotor plate 22 takes place against inhibition by the frictional contact between the drive element 4 of the piezoelectric linear drive 1 arranged in the middle of the stator 21 and the friction plate 29 of the upper rotor plate 23. By electrically exciting both actuators 3 of this piezoelectric linear drive 1, which is responsible for the movement of the upper rotor plate 23 in the second translational direction of movement T2, with the same voltage signal, preferably a sinusoidal or sawtooth-shaped voltage signal, ieIf the two opposing actuators 3 are controlled in phase, the frictional inhibition that would otherwise occur between the drive element 4 and the friction plate 29 during breakaway and movement can be reduced.

[0040] For safe and backlash-free movement of the upper rotor plate 23 in the two independent translational directions of movement T1, T2, both the middle rotor plate 22 and the upper rotor plate 23 are provided with a guide 25. The guide 25 each has a guide rail 26 and a guide receptacle 27. For axial guidance of the middle rotor plate 22 in the first independent translational direction of movement T1, a guide rail 26 is fastened to the stator 21 and received in a corresponding guide receptacle 27 of the middle rotor plate 22. For axial guidance of the upper rotor plate 23 in the second independent translational direction of movement T2, a guide rail 26 is fastened to the middle rotor plate 22 and received in a guide receptacle 27 in the upper rotor plate 22.

[0041] Furthermore, friction plates 29 are provided on the end faces of the middle runner plate 22 and on the underside of the upper runner plate 23. These friction plates are in contact with the drive elements 4 of the respective piezoelectric linear actuators 1 and enable secure movement of the middle runner plate 22 and the upper runner plate 23 in the two independent translational directions of movement T1, T2. The friction plates 29 can be preloaded relative to the drive elements 4.

[0042] The special linear arrangement of the three piezoelectric linear drives 1 on the stator 21 enables the construction of a very slim, 2-dimensionally movable linear stage 20 that does not require any movable connecting cables to power the piezoelectric linear drives 1. Furthermore, the completely separate action of the individual piezoelectric linear drives 1 on the middle slider plate 22 and the upper slider plate 23 enables complete decoupling of the movement of the upper slider plate 23 in the two independent translational directions of movement T1, T2.

[0043] The Figs. 14 to 16 show a second embodiment of a 2-dimensional linear table 20 according to the present invention in a first variant. This 2-dimensionally movable linear table 20 again has a stator 21 as a base plate, a middle slider plate 22, and an upper slider plate 23. As the perspective exploded view in Fig. 15shows, four piezoelectric linear drives 1 are fixedly arranged on this stator 21 in a central recess 28 in the base plate or the stator 21 in order to move the upper rotor plate 23 in two independent translational directions of movement T1, T2 via the respective drive elements 4. The drive elements 4 of the piezoelectric linear drives 1 each act directly on the underside of the upper rotor plate 23 or on a friction plate 29. The piezoelectric linear drives 1 arranged in the direction of the front side of the stator 21 move the middle rotor plate 22 together with the upper rotor plate 23 in the first translational direction of movement T1 when electrically excited via the drive elements 4, while the piezoelectric linear drives 1 arranged on the long side of the stator 21 in the recess 28 only move the upper rotor plate 23 in the second translational direction of movement T2.For secure axial guidance of the middle rotor plate 22 and the upper rotor plate 23, guides 25 are again provided here, which are designed as intermeshing guide rails 26.

[0044] As shown in the top view of the 2-dimensionally movable linear table 20 without the upper slide plate 23 in Fig. 16As can be clearly seen, the drive elements 4 of the piezoelectric linear drives 1 arranged in the recess 28 of the stator act exclusively on the upper rotor plate 23, so that the movement of the middle rotor plate 22 in the first translational direction of movement occurs only indirectly via the upper rotor plate 23 coupled to the middle rotor plate 22 by means of the guide rails 26 of the guide 25. In this variant of a 2-dimensionally movable linear table according to the invention, the arrangement of the piezoelectric linear drives 1 corresponding to the translational directions of movement T1, T2 makes it possible to decouple the movement of the upper rotor plate 23 in the two independent translational directions of movement T1 and T2 via a selective electrical control of the piezoelectric linear drives 1.The arrangement of the piezoelectric linear drives 1 in the recess 28 in the stator 21 and the direct drive of the piezoelectric linear drives 1 via the drive elements 4 resting on the upper rotor plate 23 results in a very flat structure of a 2-dimensionally movable linear table 20 according to the invention.

[0045] Here too, when the two laterally arranged piezoelectric linear drives 1 are only controlled to move the middle rotor plate 22 exclusively along the first translational direction of movement T1, the two actuators 3 of the two middle piezoelectric linear drives 1, which are arranged on the long sides of the stator 21 for the movement of the upper rotor plate 23 in the second translational direction of movement T2, can again be excited with an identical voltage signal in order to reduce the frictional contact between the associated drive elements 4 and the upper rotor plate 23.

[0046] The Figs. 17 and 18 show a second variant of the Fig. 14 illustrated embodiment of a 2-dimensionally movable linear table 20 according to the invention. In the perspective exploded view in Fig. 17It can be clearly seen that in this variant the four piezoelectric linear drives 1 are arranged in the recess 28 of the stator 21 rotated by 45° to the translational directions of movement T1 and T2. Here too, the drive elements 4 of the piezoelectric linear drives 1 attached to the stator 21 each act directly on the upper rotor plate 23, so that a movement of the middle rotor plate 22 in the first translational direction of movement T1 only occurs indirectly via the movement of the upper rotor plate 23. Here, too, the middle rotor plate 22 is guided in the first and second translational directions of movement T1 and T2 by guide rails 26 attached to the stator and the upper rotor plate 23 is guided by guide rails 26 attached to the middle rotor plate 22. As in the plan view shown without the middle rotor plate 22 and upper rotor plate 23 in Fig. 18As can be seen, two of the piezoelectric linear drives 1 arranged opposite one another in the recess 28 of the stator 21 move in a direction that is inclined by 45° to the translational directions of movement T1, T2. Therefore, the movement contributions of the individual piezoelectric linear drives 1 are added or subtracted to achieve a movement of the upper rotor plate 23 in the first and second translational directions of movement T1 and T2. For a movement along only one of the translational directions of movement T1 and T2, all four piezoelectric linear drives 1 are controlled simultaneously. Fig. 18Oscillation directions of the associated drive elements 4 indicated by arrows result in a movement along the translational direction of movement T2. However, control in which the oscillation direction of two opposing drive elements 4 runs in an opposite direction results in a movement of the upper rotor plate 23 and the middle rotor plate 22 along the translational direction of movement T1.

[0047] Another variant of the Fig. 14 shown embodiment of a 2-dimensional linear table 20 according to the invention show the Figures 19 and 20In contrast to the two previous variants, the two piezoelectric linear drives 1 for the movement of the middle rotor plate 22 in the first independent translational direction of movement T1 are arranged on the front sides of the stator 21 and act with their drive elements 4 directly on the middle rotor plate 22. As shown in the perspective exploded view in Fig. 19As can be seen, only two piezoelectric linear drives 1 are now provided in the recess 28 of the stator 21, the drive elements 4 of which act through the opening 24 in the middle rotor plate 22 onto the underside of the upper rotor plate 23 in order to move the upper rotor plate 23 in the second independent translational direction of movement T2. Accordingly, the movement of the upper rotor plate 23 in the first translational direction of movement T1 occurs indirectly via the movement of the middle rotor plate 22.When the two laterally arranged piezoelectric linear drives 1 are only controlled to move the middle rotor plate 22 along the first translational direction of movement T1, the two actuators 3 of the two piezoelectric linear drives 1 arranged in the recess 28 of the stator 21 can be excited with an identical voltage signal in order to reduce the friction between the associated drive elements 4 and the upper rotor plate 23. Here, too, guide rails 26 are provided on the stator 21 for guiding the middle rotor plate 22 in the first translational direction of movement T1, as well as guide rails 26 on the middle rotor plate 22 for guiding the upper rotor plate 23 in the second translational direction of movement T2.Despite the direct movement of the middle slider plate 22 via the laterally arranged piezoelectric linear drives 1 in the first translational movement direction T1, this variant again enables a very flat construction of a 2-dimensionally movable linear table 20 according to the invention as well as a decoupling of the movement of the upper slider plate 22 in the first and second translational movement directions T1 and T2.

[0048] A further embodiment of a 2-dimensional movable linear or rotary table 20 according to the invention is shown in the Figures 21 to 24 This 2-dimensional rotation table 20, designed for a rotational or tilting movement, allows a movement of the upper slide plate 22 in two independent rotational directions R1, R2, ie a movement around one of the three mutually independent axes of rotation of a solid body in free space. As shown in the perspective exploded view in Fig. 22as well as the partially cut perspective view in Fig. 23 As can be seen, this 2-dimensionally movable rotary table 20 comprises a stator 21 serving as a base plate, a middle rotor plate 22 arranged above it and an upper rotor plate 23 arranged above it. The guide 25 arranged between the stator 21 and the middle rotor plate 22 allows a secure movement of the middle rotor plate 22 and the upper rotor plate 23 coupled thereto in the first rotational movement direction R1 and the guide 25 between the middle rotor plate 22 and the upper rotor plate 23 allows a secure movement of the upper rotor plate 23 in the second rotational movement direction R2.

[0049] Furthermore, two piezoelectric linear drives 1 are arranged on the end faces of the stator 21, wherein the piezoelectric linear drives 1 are firmly connected to the stator 21 via the frame 5 and their drive elements 4 act on corresponding friction plates 29 on the end faces of the rotors 22 in order to move the middle rotor plate 22 in the first rotational direction of movement R1. Together with the middle rotor plate 22, the upper rotor plate 23 also moves indirectly in the first rotational direction of movement R1. Two further piezoelectric linear drives 1 are arranged in a recess 28 of the stator 21 and extend in the longitudinal direction of the stator 21. These piezoelectric linear drives 1, which are firmly connected to the stator 21, act via their drive elements 4 through an opening 24 in the middle rotor plate 22 directly on the upper rotor plate 23 in order to move it in the second rotational direction of movement R2.

[0050] In order to move the upper rotor plate 23 in the second rotational movement direction R2 via the piezoelectric linear drives arranged in the recess 28 of the stator 21 despite the movement coupled with the middle rotor plate 22 in the first rotational movement direction R1, the upper rotor plate 23 has a spherical or ball-shaped friction head 30 on the underside, which always ensures secure contact with the drive elements 4 of the internal piezoelectric linear drives 1 despite a rotation of the upper rotor plate 23 in the first rotational movement direction R1 and enables a rotation of the upper rotor plate 23 in the second translational movement direction R2.Here too, when only controlling the two laterally arranged piezoelectric linear drives 1 to move exclusively the middle rotor plate 22 in the first rotational direction of movement R1, the two actuators 3 of the two piezoelectric linear drives 1 arranged in the recess 28 of the stator 21, which are arranged on the long sides of the stator 21 for the movement of the upper rotor plate 23 in the second rotational direction of movement R2, can be excited with an identical voltage signal in order to reduce the frictional contact between the associated drive elements 4 and the spherical or ball-shaped friction head 30.This inventive construction of a 2-dimensionally movable rotary table 20 allows the provision of very flat rotary and tilting tables and nevertheless enables a safe and precise positioning of the upper slider plate 23 and the objects arranged thereon in two translational directions of movement R1, R2.

[0051] A further variant of a 2-dimensionally movable rotary table 20 according to the present invention, which is rotatable in two independent rotational directions R1, R2, is shown in the Figures 25 to 28shown. The structure of the rotary table 20 with a stator 21, a middle runner plate 22 and an upper runner plate 23, which are arranged one above the other and define two planes of movement between them, as well as the piezoelectric linear drives 1 arranged on the outside of the front sides of the stator 21 for moving the middle runner plate 22 in the first rotational direction of movement R1 and the guides 25 between the stator 21 and the middle runner plate 22 and between the middle runner plate 22 and the upper runner plate 23 corresponds to that shown in the Figures 21 and 22 shown embodiment. In contrast, this 2-dimensionally movable rotary table 20 has only one piezoelectric linear drive 1 fixedly connected to the stator 21 in the recess 28 of the stator 21.

[0052] In order to translate a movement of the drive element 4 of this piezoelectric linear drive 1 in a linear direction into a movement of the upper rotor plate 23 in the second rotational direction of movement R2, a flat friction plate 31 is provided on the underside of the upper rotor plate 23, which is connected to the underside of the upper rotor plate 23 via a flat spiral spring 32. Upon movement of the upper rotor plate 23 in the second rotational direction of movement R2, the flat spiral spring 32 follows with a corresponding curvature, so that an unchanged frictional contact is maintained between the drive element 4 of the piezoelectric linear drive 1 and the friction plate 31 connected to the upper rotor plate 23.When only controlling the two piezoelectric linear drives 1 arranged on the end faces of the stator 21 for moving the middle rotor plate 22 in the first rotational direction of movement R1, the two actuators 3 of the piezoelectric linear drive 1 arranged in the recess 28 of the stator 21 can be excited with an identical voltage signal in order to reduce the frictional resistance between the associated drive elements 4 and the friction plate 31 of the upper rotor plate 23. The piezoelectric linear drives 1 arranged on the outer end faces of the stator 21 for moving the middle rotor plate 22 in the first rotational direction of movement can also be arranged within the recess 28 of the stator and from there move the middle rotor plate 22 in the first rotational direction of movement R1. List of reference symbols

[0053] 1 Piezoelectric linear drive 2 Housing 2a Housing base (plate) 2b Housing top (hollow body or cover) 2c Membrane (elastic wall section) 3 Actuator 3a Stacked assembly 3b Side electrodes 3c Side electrodes 4 Drive element 5 Bearing structure (frame) 5a Lower part (carrier) 5b Upper part (spring element) 5c Rear part (spring element) 6 Conductor structure 6a Housing internal connection points 6b Housing external connection points 6c Conductor tracks 7 Seal 8 Circuit board 10 Linear table 11 Stator 12 Rotor plate 13 Linear guide 14 Position sensor 15 Position encoder 16 Leaf spring 17 Current and / or signal rail 20 2-dimensional linear or rotary table 21 Stator 22 Middle Runner plate 23Upper runner plate 24Opening 25Guide 26Guide rail 27Guide mount 28Recess 29Friction plate 30Friction head 31Friction plate 32Bending spring ADeflection direction of the actuators BDirection of movement of the drive element FGuide direction of the rotor relative to the stator R1, R2Rotational directions of movement T1, T2Translational directions of movement

Claims

1. A linear or rotary table (20) movable in two dimensions having a stator (21) and at least one upper slider plate movable relative to the stator (21) in two independent translational directions (T1,T2) or two independent rotary directions (R1,R2), and at least two piezoelectric linear drives (1) for moving the upper slider plate (23) in the two translational directions (T1,T2) or two rotary directions (R1,R2), wherein a central slider plate (22) is provided, the central slider plate (22) is arranged between the stator (21) and the upper slider plate (23), and wherein the at least two piezoelectric linear drives (1) are each attached to the stator (21) to move the upper slider plate (23) in the two translational directions (T1, T2) or two rotary directions (R1,R2), characterized in that at least one piezoelectric linear drive (1) attached to the stator (21) is in contact with the upper slider plate (23) through an opening (24) in the central slider plate (22) to move the upper slider plate (23) in a first translational direction (T1) or a first rotary direction (R1).

2. The linear or rotary table (20) movable in two dimensions according to claim 1, characterized in that the at least two piezoelectric linear drives (1) attached to the stator (21) are arranged at an angle to each other, preferably at an angle of 90° to each other.

3. The linear or rotary table (20) movable in two dimensions according to claims 1 or 2, characterized in that at least one guide (25) for the upper slider plate (23) is provided to guide the upper slider plate (23) relative to the stator (21) in at least one, preferably two translational directions (T1,T2) or rotary directions (R1,R2).

4. The linear or rotary table (20) movable in two dimensions according to claim 3, characterized in that a guide (25) is provided between the stator (21) and the central slider plate (22) and between the central slider plate (22) and the upper slider plate (23), respectively.

5. The linear or rotary table (20) movable in two dimensions according to claim 4, characterized in that the guide (25) between the stator (21) and the central slider plate (22) and / or the guide (25) between the central slider plate (22) and the upper slider plate (23) are configured as guide rails (26), wherein the guide rails (26) are preferably provided each on two opposite sides of the stator (21) and / or the central slider plate (22) and / or respectively of the central slider plate (23) and / or the upper slider plate (23).

6. The linear or rotary table (20) movable in two dimensions according to claims 1 to 5, characterized in that the upper slider plate (23) and / or the central slider plate (22) has a resilient force absorbing device (16) for absorbing a driving force of the piezoelectric linear drives (1).

7. The linear or rotary table (20) movable in two dimensions according to claims 1 to 6, characterized in that the at least two piezoelectric linear drives (1) are configured as at least two piezoelectric frictional contact actuators.

8. The linear or rotary table (20) movable in two dimensions according to claim 7, characterized in that the at least two piezoelectric frictional contact actuators each have at least one actuating element (4) configured as a friction element, wherein the friction elements are arranged such to be in frictional contact with the upper slider plate (23) or with the central slider plate (22) and the upper slider plate (23) in order to move the upper slider plate (23) in the two translational directions (T1,T2) or two rotary directions (R1,R2).

9. The linear or rotary table (20) movable in two dimensions according to claims 1 to 8, characterized in that the at least two piezoelectric linear drives (1) are configured as at least two encapsulated piezoelectric linear drives (1), in particular configured as encapsulated piezoelectric inertial or resonance drives, and having a housing (2), at least two actuators (3) arranged within the housing (2) and comprising an electromechanical material, the actuators (3) arranged such that each generates a deflection when excited by an electric control voltage, and a driving element (4) arranged outside the housing (2), wherein an elastic wall portion (2c) of the housing (2), which is elastically deformed by the deflection of the actuators (3), couples the actuators (3) and the driving element (4) to each other in such a way, that the driving element (4) is set in motion by the deflection of the actuators (3).

10. The linear or rotary table (20) movable in two dimensions according to claim 9, characterized in that the housing (2) consists of two or more housing parts (2a, 2b), wherein the housing parts (2a, 2b) are preferably connected to one another with the interposition of at least one sealing element (7), in particular are connected to one another in a hermetically sealed manner, wherein the sealing element (7) preferably consists of epoxy resin, an adhesive or a rubber-elastic material.

11. The linear or rotary table (20) movable in two dimensions according to claim 10, characterized in that a first housing part is configured as a preferably planar plate (2a) and a second housing part is configured as an open hollow body (2b) closable by the planar plate (2a) and having a cavity for receiving the actuators (3), wherein preferably the open hollow body (2b) comprises the elastic wall portion (2c), which is aligned parallel to the first housing part in a closed state of the housing (2).

12. The linear or rotary table (20) movable in two dimensions according to claims 8 to 11, characterized in that the encapsulated piezoelectric linear drives (1) (1) have an electrical conductor structure (6) having inside housing connection points (6a) and outside housing connection points (6b), which are connected by conductor paths (6c), wherein the actuators (3) are electrically connected to the inside housing connection points (6a), preferably by an electrically conductive adhesive, and wherein the outside housing connection points (6b) are preferably configured for connection to a control device for controlling the actuators (3).

13. The linear or rotary table (20) movable in two dimensions according to claim 12, characterized in that the inside housing connection points (6a), the outside housing connection points (6b) and the conductor paths (6c) extend in the same plane, preferably on a side of the first housing part (2a) facing the second housing part (2b).

14. The linear or rotary table (20) movable in two dimensions according to claims 8 to 13, characterized in that the encapsulated piezoelectric linear drives (1) (1) comprise a support (5a) and a spring means (5b) urging the housing (2) against the support (5a), wherein the actuating element (4) is preferably arranged on the spring means (5b).

15. The linear or rotary table (20) movable in two dimensions according to claim 14, characterized in that the support (5a) and the spring means (5b) form a frame (5) enclosing the housing (2), wherein the spring means (5b) is preferably configured as a spring element (5a) spanning the housing (2).

16. A method for moving a linear or rotary table (20) movable in two dimensions, the linear or rotary table (20) comprising: a stator (21), at least one upper slider plate (23) which can move relative to the stator (21) in two independent translational directions (T1, T2) or two independent rotary directions (R1, R2), a central slider plate (22) arranged between the stator (21) and the upper slider plate (23), and at least two, preferably four, piezoelectric linear drives (1) attached to the stator (21), for moving the upper slider plate (23) in the two translational directions (T1,T2) or two rotary directions (R1,R2), wherein at least one piezoelectric linear drive (1) attached to the stator (21) is in contact with the upper slider plate (23) through an opening (24) in the central slider plate (22) and moves the upper slider plate (23) in a first translational direction (T1) or a first rotary direction (R1), and wherein for moving the upper slider plate (23) in one or both independent translational directions (T1,T2), or respectively in one or both independent rotary directions (R1,R2), the individual motion contributions of all piezoelectric linear drives (1) attached to the stator (21) are added or subtracted.

17. The method according to claim 16, wherein the at least two, preferably four, piezoelectric linear drives (1) attached to the stator (21) are inclined at an angle, preferably at an angle of 45°, to the two translational directions (T1,T2) or to the projections of the two rotational directions (R1,R2), and wherein for moving the upper slider plate (23) in one of the independent translational directions (T1,T2), or respectively in one of the independent rotary directions (R1,R2), all piezoelectric linear drives (1) attached to the stator (21) provide a substantial positive or negative motion contribution.

18. The method according to claim 16, wherein the at least two, preferably four, piezoelectric linear drives (1) attached to the stator (21) are arranged parallel to the two translational directions (T1,T2) or to the projections of the two rotational directions (R1,R2), and wherein the at least two actuators (3) of at least one piezoelectric linear drive (1), which does not provide a motion contribution for moving the upper slider plate (23) in one of the independent translational directions (T1,T2), respectively in one of the independent rotary directions (R1,R2), are controlled having the same voltage signal, preferably a sinusoidal or sawtooth voltage signal, in order to reduce the friction inhibition between the actuating element (4) of this piezoelectric linear drive (1) and the upper slider plate (23).