Angular adjustment device

Abstract

The invention relates to an angular adjustment device (1) comprising: an ultrasonic actuator (3) which includes a resonator (2) and is in the form of a piezoelectric hollow cylinder (4) having at least one planar or conical end face (5) and friction elements (6) arranged thereon; an angular adjustment element (8) which has a spherical friction surface (7), is pressed against the friction elements (6), and can be adjusted about any axis with respect to its angular position by means of the ultrasonic actuator (3); and an electrical excitation device (26), wherein the resonator (2) is divided into three identical segments (9) by three virtual diametrical half-planes (P1, P2, P3), and wherein each of these segments (9) has an excitation electrode (10), a common electrode (11), and piezoelectric material (17) arranged between the excitation electrode (10) and the common electrode (11), and each segment forms a generator of an acoustic standing wave (12), wherein one of the friction elements (6) is arranged on at least one end face (5) of each of the segments (9), either between the segments (9) or in the central region of a segment (9). The invention also relates to a method for operating such an angular adjustment device.

Description

Description Angle adjustment device

[0001] The invention relates to an angle adjusting device according to claims 1 to 11 and a method for operating such an angle adjusting device according to claims 12 to 14.

[0002] DE 195 22 072 C1 discloses a piezoelectric motor in which a traveling wave is excited around the circumference of a hollow cylindrical resonator using a three-phase electrical excitation. A rotor is pressed against the end faces of the hollow cylinder, which is caused to rotate around the cylinder's longitudinal axis by the traveling wave.

[0003] DE 10 2015 120 282 B4 discloses a micropositioning device that uses a piezoelectric ultrasonic actuator to enable rotation or angular positioning of the driven element around three spatial axes. This occurs by exciting acoustic standing waves in the hollow cylindrical resonator of the actuator using generators of the same name. The generators are formed by regions of the resonator. A disadvantage of the invention is that the acoustic wave generators occupy only a small area of ​​the resonator, namely 60°, or one-sixth of the total resonator volume, so that the piezoelectric material of the resonator is not utilized efficiently. As a result, the potentially greater force or dynamics of the drive are not achieved.

[0004] It is an object of the invention to provide a piezoelectrically driven angle adjustment device with a greater drive force and higher dynamics, with the aid of which a position adjustment or positioning of an object about three spatial axes is possible, wherein the angle adjustment device simultaneously has a comparatively simple construction so that it can be manufactured cost-effectively.

[0005] The object of the invention is achieved by an angle adjustment device whose ultrasonic drive comprises a system of generators of acoustic waves which undergo a specific electrical excitation in order to achieve a greater or more efficient utilization of the active resonator volume. This allows for a simpler design of the actuator or excitation device while simultaneously increasing the driving force and dynamics.

[0006] The angle adjustment device according to the invention comprises: an ultrasonic actuator containing a resonator in the form of a piezoelectric hollow cylinder with at least one flat or conical end face on which friction elements are arranged; an angle adjustment element having a spherical friction surface and pressed against the friction elements, which angle adjustment element can be adjusted about each axis with respect to its angular position by the ultrasonic actuator; and an electrical excitation device. The resonator is divided into three equal segments by three virtual diametrical half-planes, each of which contains an excitation electrode and a common electrode with piezoelectric material arranged therebetween, thereby forming a generator of acoustic standing waves. One of the friction elements is arranged on at least one end face of each segment, either between the segments or in the central region of each segment.

[0007] An advantageous design of the acoustic standing wave generators utilizes a larger volume of the piezoelectric resonator, resulting in greater drive force and higher dynamics of the angle adjustment device. The friction elements are arranged in areas of maximum axial and tangential vibration amplitudes, thus achieving the maximum possible drive force.

[0008] In addition, it can be advantageous if the ratio of the length L of the center line of a segment to the height H of this segment, i.e. L:H, is 2 to 3. In this case, the wavelength A / 2 in the axial direction of the hollow cylindrical resonator 2 is equal to the wavelength A / 2 along the center line L of a segment, so that the resonance frequencies of the two oscillation modes differ only slightly. This allows both oscillation modes to be excited at the same frequency. which simplifies the electrical control of the ultrasonic actuator.

[0009] It may also be advantageous to arrange the excitation electrodes on one of the curved surfaces of the piezoelectric hollow cylinder and the common electrodes on the other curved surface of the piezoelectric hollow cylinder. This reduces the excitation voltage required for the resonator.

[0010] It may also be advantageous for the excitation electrodes, the common electrodes, and the piezoelectric material arranged between them to be formed as alternating, flat layers running perpendicular to the longitudinal axis of the hollow cylinder. Such a multilayer structure enables a reduction in the excitation voltage, which is highly advantageous, for example, in medical technology.

[0011] It may also be advantageous for the angle adjustment element, which has a spherical surface, to be pressed against the friction elements by a thin and long elastic element. The elastic element is arranged in a cylindrical or conical channel located in the body of the angle adjustment element and running collinearly with the longitudinal axis of the piezoelectric hollow cylinder. One end of the elastic element is fastened in the geometric center of the spherical friction surface of the angle adjustment element, and its other end is fastened to a base body, which has a sound-insulating element and on which the piezoelectric hollow cylinder is supported, at an intersection point of the longitudinal axis of the piezoelectric hollow cylinder with the base body. With such an arrangement of the elastic element, a contact force acts on the angle adjustment element along the longitudinal axis of the cylindrical resonator.When the angle adjustment element is rotated, no restoring force is exerted on it.

[0012] It may be advantageous for the elastic element to be a long elastic thread made of a silicone-containing material or rubber or another similar material or as metallic spiral spring. This type of elastic element allows for space-saving placement within the hollow cylindrical resonator.

[0013] It can be advantageous for the angle adjustment element to have two flat surfaces, or a first and a second flat surface. Such flat surfaces can be produced cost-effectively and can be used to accommodate additional system elements, for example a mirror, laser emitter, or optical waveguide. It can be advantageous for the first of the flat surfaces of the angle adjustment element to be located within the resonator, with a plate-shaped element or an element with a spherically shaped surface made of a ferromagnetic material being arranged on this first flat surface. Furthermore, it can be advantageous for a cylindrical or disc-shaped permanent magnet to be arranged on the base body within the ultrasonic actuator, which is in operative contact with the ferromagnetic element arranged on the angle adjustment element.The use of the permanent magnet in conjunction with the ferromagnetic element ensures that the angle adjustment element is pressed against the friction elements. It is, of course, conceivable for the angle adjustment element to have more than two flat surfaces.

[0014] It can also be advantageous for the ultrasonic actuator to be mounted on a sound-damping base, which in turn rests against the base body. The sound-damping base prevents the transmission of ultrasound from the resonator to the base body or the entire structure.

[0015] It may also be advantageous for a mirror, a laser emitter, or a waveguide to be arranged directly or indirectly on the second flat surface of the angle adjustment element. This allows for the realization of an angle adjustment device for deflecting a laser beam.

[0016] It may also be advantageous for the angle adjustment element to be equipped with a position sensor. This enables precise positioning of the angle adjustment element.

[0017] It is also an object of the invention to provide a method for operating an angle adjustment device as outlined above.

[0018] This task is preferably achieved by simultaneously driving two adjacent generators with an electrical voltage of the same phase from the electrical excitation device. Such excitation of the generators of an acoustic standing wave enables the use of an even larger volume of the piezoelectric resonator, thus permitting a further increase in the driving force and dynamics of the angle adjustment device.

[0019] The above object can also be advantageously achieved by simultaneously driving the acoustic standing wave generators with three electrical voltages with a phase angle of 120° between them from the electrical excitation device. Such excitation of the acoustic wave generators enables the rotation of the angle adjustment element around the longitudinal axis of the resonator. At the same time, the entire volume of the piezoelectric resonator is utilized, resulting in greater driving force and higher dynamics of the angle adjustment device.

[0020] Furthermore, the above-mentioned problem can be solved by controlling the third longitudinal mode of a standing wave on the resonator circumference and the first longitudinal mode in the axial direction. This allows the angle adjustment element to be driven around the longitudinal axis of the resonator and around any axis perpendicular to this axis.

[0021] Further details, advantages and features of the invention will become apparent from the following description and the drawings, to which reference is expressly made for all details not described in the text.

[0022] Figures 1a) and b): an embodiment of the angle adjustment device according to the invention with an angle adjustment element in the form of a spherical section in different views

[0023] Figures 2a) and b): different embodiments of a piezoelectric ultrasonic actuator of an angle adjustment device according to the invention in perspective view

[0024] Fig. 3a): Section of the piezoelectric resonator with the excitation electrode on one curved surface and with the common electrode on the other curved surface; Fig. 3b) Section of the piezoelectric resonator with excitation electrodes, common electrodes and the piezoelectric material arranged between them as alternating, flat layers running perpendicular to the longitudinal axis of the hollow cylinder

[0025] Figures 4a) to d): Representations to illustrate the functioning of an ultrasonic actuator of an angle adjustment device according to the invention for the angular adjustment of the actuating element about an axis perpendicular to the longitudinal axis of the hollow cylinder

[0026] Figures 5a) and b): Deformations of the ultrasonic actuator of an angle adjustment device according to the invention calculated by means of FEM simulation when controlling the electrodes according to Fig. 4a)

[0027] Fig. 6a): Block diagram relating to an embodiment for electrically controlling the electrodes arranged on the curved surfaces of the ultrasonic actuator of an angle adjustment device according to the invention, as shown in Fig. 2a); Fig. 6b): Block diagram relating to an embodiment for electrically controlling the electrodes arranged on the curved surfaces of the ultrasonic actuator of an angle adjustment device according to the invention, as shown in Fig. 2b).

[0028] Fig. 7a): Block diagram relating to an embodiment for a three-phase electrical control of the ultrasonic actuator of an angle adjustment device according to the invention for achieving a movement of the actuating element about the longitudinal axis; Fig. 7b) the movement paths of the friction elements achievable by means of the control according to the illustration in Fig. 7a), and in Fig. 7c) the achievable movement directions of the actuating element with electrical control of the electrodes according to Fig. 7a).

[0029] Figures 8a) and b): Deformations of the ultrasonic actuator of an angle adjustment device according to the invention calculated by means of FEM simulation with three-phase control of the electrodes according to Fig. 7a)

[0030] Fig. 9: Sectional view of the angle adjustment device according to the invention to illustrate the pressing of the adjusting element against the friction elements by means of a spring (Fig. 9a)) or by means of a permanent magnet (Fig. 9b))

[0031] Fig. 10: Angle adjustment device according to the invention with a mirror arranged on the flat surface of the adjusting element (Fig. 10a)) or with a laser emitter arranged on the flat surface (Fig. 10b))

[0032] Fig. 11: Block diagram relating to a further embodiment for the electrical excitation device of an angle adjustment device 1 according to the invention

[0033] The angle adjustment device 1 according to the invention, as shown in Fig. 1, comprises an ultrasonic actuator 3, which is designed as a resonator 2 (see, for example, Fig. 2) in the form of a hollow cylinder 4 made of a piezoelectric material with friction elements 6 arranged on the flat end faces 5. The friction elements 6 of the ultrasonic actuator 3 are elastically pressed against the spherically shaped friction surface 7 of the angle adjustment element 8 by a compressive force. The angle adjustment element 8 is designed as part of a sphere, but it can also be designed as a complete sphere. Other shapes of the angle adjustment element 8, depending on the design of the angle adjustment device, are also conceivable.

[0034] The compressive force with which the friction elements 6 are elastically pressed or pushed against the spherically shaped friction surface 7 of the angle adjusting element 8 can be realized, for example, by magnets or springs. The compressive force acting on the angle adjusting device according to the invention and its direction is shown in Fig. 1 by the arrows 15. Two different embodiments of the angle adjusting device according to the invention for pressing the friction surface 7 of the angle adjusting element 8 against the friction elements 6 are shown in Fig. 9a) and b). The movements or directions of movement of the angle adjusting element 8 that can be achieved with the angle adjusting device according to the invention are shown in Fig. 1a) by the arrows 23.

[0035] Figures 2a) and b) show, in a perspective view, two different embodiments of the ultrasonic actuator 3 of an angle adjustment device 1 according to the invention. The piezoelectric hollow cylinder 4 can be divided into three equal segments 9 by three virtual diametrical half-planes P1, P2, P3, wherein the virtual diametrical half-planes run through and along the longitudinal axis 14 of the hollow cylinder. A friction element 6 is arranged on at least one of the two flat end faces 5 of each segment 9, which is positioned either between adjacent or neighboring segments 9 symmetrically to the corresponding virtual diametrical half-plane P1, P2, P3 or in the central region of each segment 9.

[0036] Fig. 3a) shows in detail one of the segments 9 of the piezoelectric hollow cylinder 4, wherein the ultrasonic actuator 3 has the excitation electrode 10 on one of its two curved surfaces 13 and the common electrode 11 on the other of its two curved surfaces 13. Between the electrodes 10 and 11 is a layer of piezoelectric material 17 in the form of a piezoceramic. The electrodes 10 and 11 and the layer of piezoelectric ceramic 17 between them form an acoustic standing wave generator 12. The layer of piezoelectric ceramic 17 is polarized normal to the electrodes 10 and 11, with the polarization indicated in Fig. 3 by arrows and the index p. The excitation electrode 10 has the terminal 27, while the common electrode 11 has the terminal 28.

[0037] Fig. 3b) shows in detail one of the segments 9 of the piezoelectric hollow cylinder 4, which has a multilayer structure of the surface electrodes 10 and 11. In this case, the electrodes 10 and 11 are arranged perpendicular to the longitudinal axis 14 of the hollow cylinder 4, and the layers of piezoelectric ceramic 17 between each two adjacent surface electrodes 10 and 11 are also polarized perpendicular to the electrodes 10 and 11, as indicated by the arrows with the index p.

[0038] Figures 4a) to d) serve to explain the operation of the ultrasonic actuator 3 of the angle adjustment device according to the invention shown in Fig. 2a) when an acoustic standing wave is generated in the resonator 2, which propagates along its axis 14. To generate such a wave, the excitation electrodes 10 of a pair of segments 9 are connected to one another. The common electrodes 11 of these two segments are also connected to one another, as shown in Fig. 4a). Both electrode pairs are connected to the electrical excitation device 26, which provides the electrical voltage U, the frequency fr of which corresponds to the frequency of the generated wave.

[0039] When the acoustic standing wave propagating along axis 14 is generated in resonator 2, the resonator 2 oscillates as shown in Fig. 4b with dotted lines. The deformations of resonator 2 calculated using FEM simulation are shown in Figures 5a and b.

[0040] The friction element 6 located between the two controlled generators 12 moves with maximum amplitude on a linear movement path 23. The other friction elements 6 oscillate with a significantly lower and negligible amplitude. Therefore, the angle adjustment element 8 undergoes an angular movement in the virtual diametrical half-plane P1, P2, or P3 located between the two controlled generators 12. The corresponding direction of movement of the adjustment element 8 is indicated by a continuous arrow in Figures 3c) and d). Upon corresponding excitation of other pairs of segments 9 or generators 12, the angle adjustment element 8 moves in the directions indicated by dotted lines in Figure 3c).

[0041] The operation of the actuator shown in Fig. 2b) is analogous, with the respective segments 9 being controlled individually by the electrical excitation source 26.

[0042] Fig. 6a) shows a block diagram relating to the connection of the ultrasonic actuator 3 of Fig. 2a) of an angle adjustment device according to the invention with an electrical excitation device 26. The corresponding circuit comprises a generator 39 for the electrical voltage U and three switches S13, S12, S23 for the excitation electrodes 10. To implement the function shown in Fig. 3 for each friction element 6 or to adjust the angle adjustment element 8 by any angle about an axis perpendicular to the longitudinal axis 14, the switches S13, S12, S23 are individually closed according to an algorithm calculated by a controller not shown in Fig. 6, and thus a respective pair of the generators 12 of a standing wave is connected to the excitation device 26 via the terminals 27.

[0043] Fig. 6b) shows a block diagram of the connection of the ultrasonic actuator 3 from the illustration Fig. 2b) of an angle adjustment device 1 according to the invention with an electrical excitation device 26. To implement the function shown in Fig. 3 for each friction element or for adjusting the angle adjustment element 8 by any angle about an axis running perpendicular to the longitudinal axis 14, the switches S1, S2, S3 are closed individually according to a controller algorithm not shown in Fig. 6 calculated and thus a respective pair of the generators 12 of a standing wave is connected via the connections 27 to the excitation device 26.

[0044] Figures 7a) to c) serve to explain the operation of the ultrasonic actuator 3 when an acoustic traveling wave is generated therein, which propagates along the circumference of the waveguide resonator 2, designed as a piezoelectric hollow cylinder 4. Fig. 7b) shows the unwound outer surface of the ultrasonic actuator 3.

[0045] The electrical excitation device 26 provides three identical alternating voltages U1, U2, U3 with a phase difference of 120° from each other and a frequency equal to the frequency fr of the generated acoustic traveling wave. To generate such a traveling wave, the excitation electrodes 10 of all generators 12 of a standing wave are supplied with the three voltages U1, U2, U3 from the excitation source via terminals 27. The common electrodes 11 of the generators 12 are only connected to each other.

[0046] By applying the electrical voltages U1, U2, U3 to the generators 12, the generators 12 generate three standing waves, which superimpose themselves to form a running wave, which moves along the circumference of the resonator 2. With such a wave, the waveguide resonator 2 oscillates as shown in Figures 8a) and b). The direction of movement of the friction elements 6 or the angle adjustment element 8 depends on the direction of travel of the traveling wave and can be changed by exchanging two excitation voltages. If, for example, the phase angle between the voltages U1 and U2 is 120°, the wave travels clockwise. In this case, all friction elements 6 move on the inclined elliptical paths of movement 25 shown with solid lines in Fig. 7b). Such a movement of the friction elements 6 causes the adjustment element 8 to rotate clockwise around the longitudinal axis 14. In Figs. 6b) and c), the direction of movement is indicated by a solid arrow. If the phase angle is changed to -120°, the wave changes direction.The friction elements move along oppositely inclined movement paths 25. In Fig. 6b), these movement paths are shown as dotted ellipses. In this case, the angle adjustment element 8 performs a rotational movement in the opposite direction around the longitudinal axis 14. This opposite direction is shown as a dotted line in Figs. 7b) and c).

[0047] The pressing of the angle adjustment element 8 against the friction elements 6 can be achieved - as shown in Fig. 9a) - by means of a long, thin elastic element 18. The angle adjustment element 8 has a cylindrical channel 19. The elastic element 18 runs within the channel and is attached at one of its ends to the geometric center O of the spherical friction surface 7 of the angle adjustment element 8. The term "geometric center" refers to the center point of the entire sphere, of which the friction surface is a part. The elastic element 18 is attached at its other end to a base body 30. The attachment point is located at the intersection point X of the longitudinal axis 14 of the wooden cylindrical resonator 2 with the base body 30. The channel 19 can also have a conical shape.

[0048] The ultrasonic actuator 3 is supported on a sound-insulating base 29, which lies on the base body 30 and prevents the transmission of ultrasonic waves to the base body and to the overall structure.

[0049] Another possible way of pressing the adjusting element 8 against the friction elements 6 using a permanent magnet 32 ​​is shown in Fig. 9b. Here, the angle adjusting element 8 has a first flat surface 33 located within the actuator 3 and on which an element 31 made of a ferromagnetic material is arranged, having an at least partially spherically shaped surface. A cylindrical or disc-shaped permanent magnet 32 ​​is arranged on the base body 30 within the wooden-cylindrical ultrasonic actuator 3 and is in operative contact with the ferromagnetic element 31.

[0050] The angle adjustment element 8 of the angle adjustment device 1 according to the invention can, as shown in Fig. 10a), contain a mirror 34 arranged on a second flat surface 33. This allows for the realization of a device for the precise deflection of a laser beam. It is also conceivable for a laser emitter to be placed directly or indirectly on the second flat surface 33 of the angle adjustment element 8, for example, on a carrier board 21, as shown in Fig. 10b. This allows for the realization of a system in which a precise deflection of a laser beam can be achieved.

[0051] The ultrasonic actuator 3 of the actuating device 1 according to the invention has a small elementary step, which lies in the range of 0.1 to 1 pm. The angle actuating element 8 can thus be finely positioned at any desired position.

[0052] The angle adjustment device 1 according to the invention can, as shown in Fig. 11, contain a position sensor 37 and a position controller 36 for the angle adjustment element 8. An optical position sensor, a magnetic position sensor, or any other sensor that ensures the required measurement accuracy for the respective position of the angle adjustment element 8 can be used as the position sensor 37. A single microprocessor or a programmable controller contained in the control computer of the device can be used as the controller 36. By controlling the movement and position of the angle adjustment element 8 with the controller 36 The signal from the encoder 37 makes it possible to achieve the specified precision, which is in the range of 2 to 3 elementary steps, for the movement path and positioning. Furthermore, an electrical voltage generator 38 or a signal generator can be housed in the controller. This provides the small-signal voltages required for the operation of the actuator with the appropriate phase angles and frequencies. The small-signal voltages are amplified to the required value by the power output stage 39 and passed to the ultrasonic actuator 3.

[0053] List of reference symbols: 1 : Angle adjustment device 2: Resonator 3: Ultrasonic actuator 4: piezoelectric hollow cylinder 5: flat front surface (of the piezoelectric hollow cylinder 4) 6: Friction element 7: spherical friction surface (of the angle adjustment element 8) 8: Angle adjustment element 9: Segment (of the piezoelectric hollow cylinder 4) 10: Excitation electrode 11 : common electrode 12: Generator (of an acoustic standing wave) 13: curved surface (of the piezoelectric hollow cylinder 4) 14: Longitudinal axis (of the piezoelectric hollow cylinder 4) 15: Force arrow 16: Shift 17: piezoelectric material 18: elastic element 19: Channel (of the angle adjustment element 8) 20: sound-insulating element 21 : Carrier board 22: Spherical section 23: Movement direction arrows linear motion path elliptical motion path electrical excitation device Connection (of the excitation electrode 10) Connection (of the common electrode 11) sound-insulating pad Base body ferromagnetic element Permanent magnet flat surfaces (of the angle adjustment element 8) Mirror Laser emitter Position controller Position sensor Generator (electrical voltages) Power amplifier

Claims

Claims Claim 1 Angle adjustment device (1) comprising: an ultrasonic actuator (3) containing a resonator (2) in the form of a piezoelectric hollow cylinder (4) with at least one flat or conical end face (5) and friction elements (6) arranged thereon; an angle adjustment element (8) having a spherical friction surface (7) and pressed against the friction elements (6), which angle adjustment element is adjustable about each axis with respect to its angular position by the ultrasonic actuator (3);and an electrical excitation device (26), characterized in that the resonator (2) is divided into three equal segments (9) by three virtual diametrical half-planes (P1, P2, P3), and in that each of these segments (9) has an excitation electrode (10), a common electrode (11) and piezoelectric material (17) arranged between the excitation electrode (10) and the common electrode (11) and forms a respective generator of an acoustic standing wave (12), wherein on at least one end face (5) of each of the segments (9) one of the friction elements (6) is arranged either between the segments (9) or in the central region of a segment (9); Claim 2 Angle adjustment device (1) according to claim 1, characterized in that the excitation electrodes (10) are arranged on one of the curved surfaces (13) of the piezoelectric hollow cylinder (4) and the common electrodes (11) are arranged on the other of the curved surfaces (13) of the piezoelectric hollow cylinder (4). Claim 3 Angle adjustment device (1) according to claim 1 or 2, characterized in that the excitation electrodes (10), the common electrodes (11) and the piezoelectric material arranged between adjacent excitation electrodes (10) and common electrodes (11) are designed as alternating, flat layers (16) running perpendicular to a longitudinal axis (14) of the piezoelectric hollow cylinder (4). Claim 4 Angle adjustment device (1) according to one of the preceding claims, characterized in that the spherical friction surface (7) of the angle adjustment element (8) is pressed onto the friction elements (6) by means of a thin and long elastic element (18), wherein the elastic element (18) is arranged in a cylindrical or conical channel (19) of the angle adjustment element (8), wherein the channel (19) runs collinearly with the longitudinal axis (14) of the piezoelectric hollow cylinder (4), and wherein one end of the elastic element (18) is fastened in the geometric center (O) of the spherical friction surface (7) of the angle adjustment element (8), and its other end is fastened to a base body (30) supporting the piezoelectric hollow cylinder (4) at the point of intersection (X) of said base body with the longitudinal axis (14) of the piezoelectric hollow cylinder (4), wherein a sound-insulating element (20) is arranged between the base body (30) and the piezoelectric hollow cylinder (4). Claim 5 Angle adjustment device (1) according to claim 4, characterized in that the elastic element (18) is designed as a thread made of a silicone-containing material or of rubber or another similar material or the elastic element (18) is designed as a metallic spiral spring. Claim 6 Angle adjustment device (1) according to one of the preceding claims, characterized in that the angle adjustment element (8) has a first and a second flat surface (33). Claim 7 Angle adjusting device (1) according to claim 6, characterized in that the first flat surface (33) of the angle adjusting element (8) is located within the resonator (2), and on this first flat surface (33) a ferromagnetic element (31) having a plate-shaped or spherical surface is arranged. Claim 8 Angle adjustment device (1) according to claim 6, characterized in that a cylindrical or disc-shaped permanent magnet (32) is arranged on the base body (30) within the ultrasonic actuator (3), which is in operative contact with the ferromagnetic element (31). Claim 9 Angle adjustment device (1) according to one of the preceding claims 6 to 8, characterized in that on the second flat A mirror, a laser emitter or a waveguide is arranged directly or indirectly on the surface (33). Claim 10 Angle adjustment device (1) according to one of the preceding claims, characterized in that the angle adjustment element (8) is equipped with a position sensor. Claim 11 Angle adjustment device (1) according to claim 1, characterized in that the ratio of the length L of the center line of a segment (9) to its height H is 2 to 3. Claim 12 Method for operating an angle adjustment device according to one of claims 1 to 10, characterized in that two adjacent generators of an acoustic standing wave (12) are controlled simultaneously with an electrical voltage of the same phase from the electrical excitation source (26). Claim 13 Method for operating an angle adjustment device according to one of claims 1 to 10, characterized in that the generators of an acoustic standing wave (12) are simultaneously controlled by the electrical excitation source (26) with three electrical voltages with a phase angle of 120° between them. Claim 14 Method for operating an angle adjustment device according to one of claims 1 to 10, characterized in that in the resonator (2) the third longitudinal mode of a standing wave on the resonator circumference and the first longitudinal mode in the axial direction are excited.

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