Piezoelectric mirror component, method for operating a piezoelectric mirror component and projection device comprising a piezoelectric mirror component

Abstract

To provide a method for operating a piezoelectric mirror component, and a projection device including the same.SOLUTION: A mirror element, a drive ring, which surrounds the mirror element and is connected to the mirror element via at least one first torsion spring element, and a frame element, which is connected to the drive ring via at least one second torsion spring element, wherein a first electrode and a second electrode, which is structured into a plurality of control regions, are applied on the drive ring, A piezoelectric layer is arranged between the first electrode and the second electrode, wherein the first electrode is at least partially applied to the frame element and the piezoelectric layer is partially applied to the frame element, wherein the second electrode is applied in an active region of the frame element surrounded by an edge, wherein the active region has a smaller thickness than the edge. Furthermore, a method for operating the piezoelectric mirror component and a projection device are presented.SELECTED DRAWING: None

Description

[Technical Field]

[0001] A piezoelectric mirror element, a method for operating the piezoelectric mirror element, and a projection device comprising the piezoelectric mirror element are presented. [Background technology]

[0002] Laser projectors have many application areas. For example, projectors are used to display moving images, for example in cinemas, for home theater applications, or for mobile display applications. It is particularly preferable for inexpensive and vibration-resistant projectors to be available for this purpose. Furthermore, projectors are increasingly used in the automotive field, for example to project information onto road surfaces, for matrix lighting, or even for applications based on the LIDAR principle (LIDAR: "Light Detection and Ranging"). Such applications require the large depth of field that laser projectors can provide. Furthermore, laser projectors are advantageous for applications related to VR ("Virtual Reality") and AR ("Augmented Reality"), for example in AR / VR glasses.

[0003] The projector may include a rotatable mirror that deflects a time-modulated laser beam. In this way, an image is generated within the observer's perceived far field, so that the projected image is always in focus for the observer and does not require eye accommodation. In the case of AR / VR glasses, the deflected beam is coupled into, for example, a waveguide lens. Here, the beam direction, not its position, determines the image point location for the observer, so no additional optics are required. Often, two mirrors are used, one for each orthogonal deflection direction, so that the laser beam scans the image area in an orthogonal grid. Alternatively, solutions using laser arrays, LED arrays (LEDs: Light Emitting Diodes), or QLED arrays (QLEDs: Quantum Dot Light Emitting Diodes) exist, but these solutions are limited in their resolution and brightness. Also, solutions in which the laser light is selectively reflected by a passive panel are not very energy-efficient. Therefore, there is a high demand for compact solutions for AR / VR glasses with good image resolution.

[0004] Micromirrors are known, for example, from the publications listed below. Non-patent document 1 describes a mirror that can oscillate around one axis, thereby enabling one-dimensional scanning. Non-patent document 2 describes a rectangular mirror that can move two-dimensionally, in one direction, the motion is anharmonic in the so-called rocking mode. Patent document 1 and non-patent document 3 describe a symmetrically suspended mirror that can move around two axes, in which the motion around both axes is similar, which can result in undesirable coupling behavior. Non-patent document 4 similarly describes a mirror that can move around two axes, in which the actuator for one of the rotational motions has a large serpentine structure, which is not very compact, allows only a low resonant frequency, and may be sensitive to shocks. Non-patent document 5 describes an electromagnetically driven mirror. [Prior art documents] [Chartered documents]

[0005]

Patent Document 1

Non-licensed literature

[0006] [Non-licensed document 1] U. Baran et al., “Resonant PZT MEMS Scanner for High-Resolution Displays”, Journal of Microelectromechanical Systems, 21, 1303-1310, 2012 [Non-licensed document 2] Ch. Pan et al., ?A New Two-Axis Optical Scanner Actuated by Piezoelectric Bimorphs”, International Journal of Optomechatronics, 6, 336-349, 2012 [Non-licensed document 3] H.-J. Quenzer et al., “Piezoelectrically driven translatory optical MEMS actuator with 7mm apertures and large displacements”, Proc. SPIE 9375, MOEMS and Miniaturized Systems XIV, 937500, 2015

Non-licensed Document 4

[0007] At least one object of certain embodiments is to provide a piezoelectric mirror component. At least one further object of certain embodiments is to provide a method for operating the piezoelectric mirror component. At least one further object of certain embodiments is to provide a projection apparatus comprising the piezoelectric mirror component. [Means for solving the problem]

[0008] These problems are solved by the products and methods according to the independent claims. Advantageous embodiments and developments of the products and methods are set out in the dependent claims and will become apparent further from the following description and drawings.

[0009] According to at least one embodiment, a piezoelectric mirror component, hereinafter also referred to as mirror component for short, comprises a mirror element, a piezoelectric drive ring, and a frame element. The drive ring surrounds the mirror element and is connected to the mirror element via at least one first torsion spring element. The frame element is connected to the drive ring via at least one second torsion spring element. The mirror element, the drive ring, and the frame element, as well as the torsion spring element, can be aligned, in particular, along a plane, in the rest state of the mirror component.

[0010] A piezoelectric layer is applied to at least the drive ring and is disposed between the first and second electrodes. The piezoelectric layer may include one or more piezoelectric materials. Particularly preferably, the piezoelectric layer includes or consists of a lead zirconate titanate (PZT)-based piezoelectric material.

[0011] At least the second electrode is preferably structured into a plurality of control regions. This means that the second electrode can have a plurality of regions that can be controlled independently of one another. The first electrode and / or the piezoelectric layer can be applied continuously or at least partially structured. Thus, the first electrode and the second electrode, structured into a plurality of control regions, are preferably applied to the drive ring, with the piezoelectric layer being disposed between the first and second electrodes. Particularly preferably, the first electrode, the piezoelectric layer, and the second electrode are applied in this order. By applying a voltage between at least one control region of the first electrode and the second electrode, mechanical deformation of the piezoelectric layer, and thus of the drive ring in a partial region, can be achieved by the inverse piezoelectric effect. A force can thereby be applied to the drive ring and / or the mirror element. Thus, each control region, together with the piezoelectric layer and the first electrode, can form a piezoelectric element, by which a partial region of the mirror element can be moved. By applying an AC signal having an oscillating voltage, an oscillating force may be exerted, which may cause an oscillating deformation, thereby causing at least a portion of the mirror element to transition into a vibrating state.

[0012] The at least one first torsion spring element and the at least one second torsion spring element can in particular be designed as a so-called torsion beam, in other words each of the torsion spring elements is elongated in the form of a beam with a longitudinal direction, which beam can perform a torsional movement around an axis of rotation, in particular during operation of the mirror element, which axis of rotation preferably substantially coincides with the longitudinal direction of the beam.

[0013] At least one first torsion spring element preferably extends from the mirror element to the drive ring and defines a first axis of rotation. When the mirror element and the drive ring rotate relative to each other about the first axis of rotation, an end of the at least one first torsion spring element closer to the mirror element rotates relative to an end of the at least one first torsion spring element closer to the drive ring. In particular, by appropriately controlling the control region of the second electrode with a first AC signal having a first frequency, the mirror element can be brought into a first rotational oscillation having the first frequency, and a restoring force, preferably linearly dependent on the rotation angle, can be applied to the mirror element via the at least one first torsion spring element. Such rotational oscillation of the at least one torsion spring element is hereinafter also referred to as a torsional oscillation. Therefore, the first rotational oscillation can also be referred to as a first torsional oscillation.

[0014] At least one second torsion spring element preferably extends from the drive ring to the frame element and defines a second rotation axis. When the frame element and the drive ring are rotated relative to each other about the second rotation axis, an end of the at least one second torsion spring element closer to the frame element rotates relative to an end of the at least one second torsion spring element closer to the drive ring. In particular, by appropriately controlling the control region of the second electrode with a second AC signal having a second frequency, the drive ring can be transitioned to a second rotational oscillation having a second frequency, and a restoring force, preferably linearly dependent on the rotation angle, can be applied to the drive ring via the at least one second torsion spring element. In particular, the mirror element can perform the second rotational oscillation together with the drive ring. The above-mentioned second rotational oscillation may also be referred to as a second torsional oscillation.

[0015] Particularly preferably, the first and second torsion spring elements are arranged rotated by 90° relative to each other, so that the first axis of rotation for the first torsional vibration and the second axis of rotation for the second torsional vibration are perpendicular to each other, thereby achieving as much independence of the first and second torsional vibrations as possible.

[0016] According to a further embodiment, the frame element may also be at least partially coated with a first electrode. Furthermore, the frame element may also be at least partially coated with a piezoelectric layer. Additionally, the frame element may also be at least partially coated with a second electrode. Furthermore, the at least one second torsion spring element may also be coated with a first electrode and / or a piezoelectric layer. Furthermore, the at least one second torsion spring element may be free of a second electrode. Particularly preferably, the at least one first torsion spring element and the mirror element are free of a first electrode, a piezoelectric layer, and a second electrode.

[0017] According to a further embodiment, the second electrode on the frame element is structured into a plurality of control areas. In particular, the second electrode can be applied to an actuation area of ​​the frame element that is surrounded by the edge of the frame element. This allows for further control areas to be provided on the frame element in addition to the control area on the drive ring, by means of which a force can be applied to, for example, the drive ring in an appropriate manner.

[0018] Furthermore, contact elements for controlling the first and second electrodes may be present on the frame element, for example on the edge of the frame element. The control areas on the drive ring and / or on the frame element may be connected to the contact elements on the frame element via conductive paths that extend over at least one second torsion spring element. Alternatively, the conductive paths may be omitted and the electrodes may be bonded directly onto the electrodes, thereby avoiding parasitic resistance and capacitance that may occur in connection with conductive paths.

[0019] In the method for operating a piezoelectric mirror element, as described above, the mirror element is preferably driven into a first torsional oscillation by a first AC signal having a first frequency acting on a first control region. The drive ring, preferably together with the mirror element, is driven into a second torsional oscillation by a second electrical AC signal having a second frequency acting on a second control region. In particular, the control by the first AC signal and the control by the second AC signal can be performed simultaneously. As a result, in particular, the mirror element can simultaneously perform two torsional oscillations: the mirror element oscillates relative to the drive ring about a first rotation axis at a first frequency, and the drive ring, together with the mirror element, oscillates relative to the frame element about a second rotation axis at a second frequency. The first and second frequencies can be resonant frequencies or can be close to the resonant frequencies, which can depend in particular on the respective vibrating parts of the mirror element and their geometrical configuration. In particular, the first and second frequencies are different.

[0020] According to a further embodiment, the projection device comprises a laser light source and a piezoelectric mirror element. During operation, the mirror element can deflect the laser light emitted by the laser light source. Due to the aforementioned torsional vibration of the mirror element, an image area perceptible by the observer can be filled with the deflected laser light. In other words, scanning can be achieved by the mirror element. Particularly preferably, so-called Lissajous scanning can be achieved in resonant or near-resonant torsional vibrations about a first rotation axis and a second rotation axis, which are particularly preferably perpendicular to each other.

[0021] The features and embodiments described above and below apply equally to piezoelectric mirror elements, methods for operating piezoelectric mirror elements, and projection devices comprising piezoelectric mirror elements.

[0022] According to a further embodiment, the drive ring has a first diameter along a first direction and a second diameter along a second direction perpendicular to the first direction, the first diameter being different from the second diameter. Particularly preferably, the first diameter is larger than the second diameter. Thus, the drive ring does not have a circular shape. In particular, the drive ring may have an elliptical shape or at least approximate an elliptical shape.

[0023] The drive ring may be bounded by an inner edge facing the mirror element and an outer edge on the opposite side in a direction along a plane spanned by the first and second directions. The inner and outer edges may each have an elliptical shape or at least a shape approximating an elliptical shape. The shape of the outer edge may be defined by a first diameter and a second diameter. In other words, the aforementioned first and second diameters may be the first and second outer diameters of the drive ring. The inner edge has first and second diameters, which may also be referred to as first and second inner diameters, where the first inner diameter extends along the first direction and the second inner diameter extends along the second direction, respectively. The ratio between the first outer diameter and the second outer diameter may be the same as or different from the ratio between the first inner diameter and the second inner diameter. If the ratios are different, this may mean that the drive ring has a first width along the first direction and a second width along the second direction, where the first width is different from the second width. For example, the first width may be smaller than the second width.

[0024] In particular, at least one first torsion spring element is arranged along the first direction, and at least one second torsion spring element is arranged along the second direction. Particularly preferably, the drive ring is connected to the mirror element via two first torsion spring elements arranged on opposite sides of the mirror element along a line along the first direction. Furthermore, particularly preferably, the drive ring is connected to the frame element via two second torsion spring elements arranged on opposite sides of the drive ring along a line along the second direction. Each of the first torsion spring elements and each of the second torsion spring elements may have the features described in relation to the at least one first torsion spring element and the at least one second torsion spring element, respectively. In particular, the mirror element may be connected to the drive ring only by the first torsion spring element, while the drive ring may be connected to the frame element particularly preferably only by the second torsion spring element.

[0025] According to a further embodiment, the mirror element has a mirror area and an edge area surrounding the mirror area, which is preferably partially separated from the mirror area by at least one opening. The mirror element may particularly preferably be circular. Consequently, at least one opening may have the shape of an arc of a circle. Particularly preferably, there may be two openings facing each other and both having the shape of an arc of a circle.

[0026] Furthermore, the mirror region may be elliptical and may have a larger elliptical axis and a smaller elliptical axis. Preferably, the larger elliptical axis is oriented along a first direction and the smaller elliptical axis is oriented along a second direction. Alternatively, the larger elliptical axis may be oriented along the second direction and the smaller elliptical axis may be oriented along the first direction. In the case of an elliptical mirror region, the opening has the shape of an elliptical arc. The ratio of the larger elliptical axis to the smaller elliptical axis may preferably be greater than 1, or 1.02 or more, or 1.04 or more, or 1.06 or more, and may be 1.1 or less, or 1.08 or less, or 1.07 or less.

[0027] The edge region can be connected to the mirror region via two connection regions. In other words, the two openings can be separated from each other by the two connection regions. Particularly preferably, the connection regions are arranged on opposite sides of the mirror region along the second direction, so that the two openings can preferably face each other along the first direction.

[0028] According to a further embodiment, a reflective coating is applied to the mirror area. For example, the coating may be a metal coating. Furthermore, a dielectric coating, such as a Bragg mirror, is also possible. The edge area and the connection area may preferably be left without a reflective coating.

[0029] According to a further embodiment, the frame element surrounds the drive ring. The frame element may have an opening extending therethrough, in which at least one second torsion spring element and the drive ring with the at least one first torsion spring element and the mirror element arranged therein are arranged. The at least one second torsion spring element particularly preferably protrudes into the opening from an edge surface surrounding the opening, and thus from the frame element. The opening preferably has a polygonal basic shape, which may be, for example, quadrangular, hexagonal, or octagonal. Furthermore, the opening may be coextensive along the first and second directions. If the frame element has an actuation area, this may be directly adjacent to the opening. Furthermore, the actuation area may be partially separated from the edge by at least one opening.

[0030] According to a further embodiment, the mirror element and the drive ring have a smaller thickness than at least one frame portion of the frame element. Here and below, "thickness" may mean in particular an extension along a third direction perpendicular to the first and second directions. If the frame element has an actuation area, the actuation area may also preferably have a smaller thickness than the frame portion of the frame element.

[0031] Particularly preferably, the frame elements, drive ring, mirror elements, and torsion spring elements are formed integrally. In particular, the frame elements, drive ring, mirror elements, and torsion spring elements may comprise silicon. To produce the mirror component, a carrier, for example in the form of a silicon wafer or an SOI wafer (SOI: "silicon on insulator"), can be provided. The carrier is correspondingly structured to form the frame elements, drive ring, mirror elements, and torsion spring elements. Electrodes and piezoelectric layers can then be formed or applied to the structured carrier, as well as, depending on the design, for example, insulating layers and / or conductive tracks.

[0032] According to a further embodiment, means are provided for determining the position of the mirror element and / or the position of the drive ring and / or the frequency of the torsional vibration. For example, during operation of the piezoelectric mirror element, the second frequency can be measured in the first AC signal and the first frequency can be measured in the second AC signal. This can be achieved, for example, by using appropriate frequency filters in the drive supply lines, so that no additional lines are required. Furthermore, it is also possible to provide a third control area in which the piezoelectric signal is measured via the piezoelectric effect. The third control area can be provided at a suitable position, in particular, so that a good signal can be achieved.

[0033] Furthermore, for position and / or frequency measurements, there can be at least two electrode elements, which form a capacitor with a variable capacitance when the mirror element moves, in particular relative to the drive ring, or when the drive ring moves, in particular relative to the frame element, and the capacitance of the capacitor is measured. In such a capacitance measurement, in particular the zero crossings of the drive ring and / or the mirror element can also be determined. In order to avoid capacitive short circuits, the first electrode can be appropriately structured.

[0034] The electrode elements may be formed, for example, by conductive path portions. A first electrode element may be disposed, for example, on a frame element, while a second electrode element may be disposed adjacent to the first electrode element on the drive ring. When the drive ring moves relative to the frame element, the distance between the electrode elements may change, thereby changing the capacitance of the capacitor formed by the electrode elements. Correspondingly, for example, the electrode elements may be disposed on the drive ring and the mirror element. For example, it is possible to arrange two electrode elements on the frame element on opposite sides of the drive ring, such that the drive ring is between the two electrode elements disposed on the frame element. In this case, the drive ring can act like a moving dielectric between the electrode elements during movement, thereby changing the capacitance of the capacitor formed thereby. Correspondingly, the two electrode elements may also be disposed on opposite sides of the mirror element on the drive ring.

[0035] Furthermore, there may be a first and / or second control region that is used alternately in a time division multiplexed manner to drive the mirror elements or drive rings and to measure the piezoelectric signal.

[0036] Further advantages, advantageous embodiments and developments will become apparent from the examples described below in conjunction with the drawings. [Brief explanation of the drawings]

[0037] [Figure 1A] 1 is a schematic diagram of a piezoelectric mirror assembly according to one embodiment. [Figure 1B] 1 is a schematic diagram of a piezoelectric mirror assembly according to one embodiment. [Figure 2A] 1C is a schematic illustration of the method steps of a method for manufacturing a piezoelectric mirror component according to FIGS. 1A and 1B; [Figure 2B] 1C is a schematic illustration of the method steps of a method for manufacturing a piezoelectric mirror component according to FIGS. 1A and 1B; [Figure 2C] 1C is a schematic illustration of the method steps of a method for manufacturing a piezoelectric mirror component according to FIGS. 1A and 1B; [Figure 2D] 1C is a schematic illustration of the method steps of a method for manufacturing a piezoelectric mirror component according to FIGS. 1A and 1B; [Figure 2E] 1C is a schematic illustration of the method steps of a method for manufacturing a piezoelectric mirror component according to FIGS. 1A and 1B; [Figure 3A] 1C is a schematic illustration of method steps of a method for operating a piezoelectric mirror component according to FIGS. 1A and 1B. [Figure 3B] 1C is a schematic illustration of method steps of a method for operating a piezoelectric mirror component according to FIGS. 1A and 1B. [Figure 4A] 1A and 1B show a simulation study for a piezoelectric mirror component according to FIGS. [Figure 4B] 1A and 1B show a simulation study for a piezoelectric mirror component according to FIGS. [Figure 4C]1A and 1B show a simulation study for a piezoelectric mirror component according to FIGS. [Figure 4D] 1A and 1B show a simulation study for a piezoelectric mirror component according to FIGS. [Figure 4E] 1A and 1B show a simulation study for a piezoelectric mirror component according to FIGS. [Figure 5A] 1A and 1B show a simulation study for a piezoelectric mirror component according to FIGS. [Figure 5B] 1A and 1B show a simulation study for a piezoelectric mirror component according to FIGS. [Figure 5C] 1A and 1B show a simulation study for a piezoelectric mirror component according to FIGS. [Figure 5D] 1A and 1B show a simulation study for a piezoelectric mirror component according to FIGS. [Figure 5E] 1A and 1B show a simulation study for a piezoelectric mirror component according to FIGS. [Figure 6A] 3 is a schematic diagram of a piezoelectric mirror component according to a further embodiment; [Figure 6B] 3 is a schematic diagram of a piezoelectric mirror component according to a further embodiment; [Figure 7A] 6C is a schematic illustration of the method steps of a method for manufacturing a piezoelectric mirror component according to FIGS. 6A and 6B. [Figure 7B] 6C is a schematic illustration of the method steps of a method for manufacturing a piezoelectric mirror component according to FIGS. 6A and 6B. [Figure 7C] 6C is a schematic illustration of the method steps of a method for manufacturing a piezoelectric mirror component according to FIGS. 6A and 6B. [Figure 7D] 6C is a schematic illustration of the method steps of a method for manufacturing a piezoelectric mirror component according to FIGS. 6A and 6B. [Figure 7E] 6C is a schematic illustration of the method steps of a method for manufacturing a piezoelectric mirror component according to FIGS. 6A and 6B. [Figure 8A] 6C is a schematic illustration of method steps of a method for operating a piezoelectric mirror component according to FIGS. 6A and 6B. [Figure 8B]6C is a schematic illustration of method steps of a method for operating a piezoelectric mirror component according to FIGS. 6A and 6B. [Figure 8C] 6C is a schematic illustration of method steps of a method for operating a piezoelectric mirror component according to FIGS. 6A and 6B. [Figure 8D] 6C is a schematic illustration of method steps of a method for operating a piezoelectric mirror component according to FIGS. 6A and 6B. [Figure 8E] 6C is a schematic illustration of method steps of a method for operating a piezoelectric mirror component according to FIGS. 6A and 6B. [Figure 9A] 6A and 6B show a simulation study for a piezoelectric mirror component. [Figure 9B] 6A and 6B show a simulation study for a piezoelectric mirror component. [Figure 9C] 6A and 6B show a simulation study for a piezoelectric mirror component. [Figure 9D] 6A and 6B show a simulation study for a piezoelectric mirror component. [Figure 9E] 6A and 6B show a simulation study for a piezoelectric mirror component. [Figure 10A] 6A and 6B show a simulation study for a piezoelectric mirror component. [Figure 10B] 6A and 6B show a simulation study for a piezoelectric mirror component. [Figure 10C] 6A and 6B show a simulation study for a piezoelectric mirror component. [Figure 10D] 6A and 6B show a simulation study for a piezoelectric mirror component. [Figure 10E] 6A and 6B show a simulation study for a piezoelectric mirror component. [Figure 11A] 6A and 6B show a simulation study for a piezoelectric mirror component. [Figure 11B] 6A and 6B show a simulation study for a piezoelectric mirror component. [Figure 11C] 6A and 6B show a simulation study for a piezoelectric mirror component. [Figure 11D] 6A and 6B show a simulation study for a piezoelectric mirror component. [Figure 11E] 6A and 6B show a simulation study for a piezoelectric mirror component. [Figure 12A] 6A and 6B show a simulation study for a piezoelectric mirror component. [Figure 12B] 6A and 6B show a simulation study for a piezoelectric mirror component. [Figure 12C] 6A and 6B show a simulation study for a piezoelectric mirror component. [Figure 12D] 6A and 6B show a simulation study for a piezoelectric mirror component. [Figure 12E] 6A and 6B show a simulation study for a piezoelectric mirror component. [Figure 13A] 3 is a schematic diagram of a piezoelectric mirror component according to a further embodiment; [Figure 13B] 3 is a schematic diagram of a piezoelectric mirror component according to a further embodiment; [Figure 14A] 13C is a schematic illustration of the method steps of a method for manufacturing a piezoelectric mirror component according to FIGS. 13A and 13B. [Figure 14B] 13C is a schematic illustration of the method steps of a method for manufacturing a piezoelectric mirror component according to FIGS. 13A and 13B. [Figure 14C] 13C is a schematic illustration of the method steps of a method for manufacturing a piezoelectric mirror component according to FIGS. 13A and 13B. [Figure 14D] 13C is a schematic illustration of the method steps of a method for manufacturing a piezoelectric mirror component according to FIGS. 13A and 13B. [Figure 14E] 13C is a schematic illustration of the method steps of a method for manufacturing a piezoelectric mirror component according to FIGS. 13A and 13B. [Figure 15] 13C is a schematic illustration of method steps of a method for operating a piezoelectric mirror component according to FIGS. 13A and 13B. [Figure 16A] 13A and 13B show a simulation study for a piezoelectric mirror component. [Figure 16B] 13A and 13B show a simulation study for a piezoelectric mirror component. [Figure 16C] 13A and 13B show a simulation study for a piezoelectric mirror component. [Figure 16D] 13A and 13B show a simulation study for a piezoelectric mirror component. [Figure 16E] 13A and 13B show a simulation study for a piezoelectric mirror component. [Figure 17] 1 is a schematic diagram of a projection apparatus according to a further embodiment; [Figure 18A] 1 shows a schematic diagram of a mechanism for determining the position and / or frequency of a component of a piezoelectric mirror assembly, according to some embodiments. [Figure 18B] 1 shows a schematic diagram of a mechanism for determining the position and / or frequency of a component of a piezoelectric mirror assembly, according to some embodiments. [Figure 18C] 1 shows a schematic diagram of a mechanism for determining the position and / or frequency of a component of a piezoelectric mirror assembly, according to some embodiments. [Figure 18D] 1 shows a schematic diagram of a mechanism for determining the position and / or frequency of a component of a piezoelectric mirror assembly, according to some embodiments. [Figure 18E] 1 shows a schematic diagram of a mechanism for determining the position and / or frequency of a component of a piezoelectric mirror assembly, according to some embodiments. [Figure 19A] 4 is a schematic partial view of a piezoelectric mirror component according to a further embodiment; [Figure 19B] 4 is a schematic partial view of a piezoelectric mirror component according to a further embodiment; DETAILED DESCRIPTION OF THE INVENTION

[0038] In the examples and figures, identical, similar, or equivalently functioning elements may be respectively provided with the same reference numerals. The illustrated elements and their size ratios relative to one another are not to scale; rather, individual elements, such as layers, components, members, and regions, may be shown exaggeratedly large for better illustration and / or understanding.

[0039] 1A and 1B show schematic diagrams of a piezoelectric mirror component 100 according to one embodiment, with Fig. 1A showing a three-dimensional view of the upper side of the mirror component 100 and Fig. 1B showing a three-dimensional view of the lower side of the mirror component 100. Figs. 2A-2E show schematic diagrams of method steps of a method for manufacturing the piezoelectric mirror component 100 according to Figs. 1A and 1B in a top view. The following description relates equally to Figs. 1A and 1B and to Figs. 2A-2E.

[0040] The piezoelectric mirror assembly 100 comprises a mirror element 10, a piezoelectric drive ring 20, and a frame element 30. The drive ring 20 surrounds the mirror element 10 and is connected to the mirror element 10 via at least one first torsion spring element 41. The frame element is connected to the drive ring via at least one second torsion spring element 42. The mirror element 10, drive ring 20, and frame element 30, as well as the torsion spring elements 41 and 42, are aligned along a plane subtended by a first direction, designated "x," and a second direction, designated "y," perpendicular to the first direction, in the rest state of the mirror assembly 100. A piezoelectric layer 50 is applied to at least the drive ring 20 and is disposed between a first electrode 51 and a second electrode 52. The piezoelectric layer 50 preferably comprises or consists of a piezoelectric material based on lead zirconate titanate (PZT).

[0041] To manufacture the mirror element 100, a carrier 101, e.g., in the form of a silicon wafer or an SOI wafer, is prepared, as shown in FIG. 2A , with a carrier material consisting of an electrically insulating material and a silicon layer thereon. The carrier 101 is thinned from its underside in the region 102 where the mirror elements 10, the piezoelectric drive ring 20, the frame element 30, and the torsion spring elements 41, 42 are arranged, i.e., in the region where the mirror element 100 is mechanically active. To form the mirror elements 10, the drive ring 20, and the torsion spring elements 41, 42 in the region 102, the carrier is through-etched and thereby structured, as shown in FIG. 2B , so that openings 31 are created in the frame element 30 surrounding the drive ring 20, in which the mirror elements 10, the piezoelectric drive ring 20, the frame element 30, and the torsion spring elements 41, 42 are arranged. The frame element 30, the drive ring 20, the mirror elements 10, and the torsion spring elements 41, 42 are thus integrally formed. The opening 31 preferably has a polygonal basic shape, which may be octagonal as shown. Furthermore, it is possible for the opening 31 to be coextensive along the first and second directions.

[0042] 1A and 1B, the mirror element 10 and drive ring 20, as well as the torsion spring elements 41, 42, have a smaller thickness than the frame element 30 due to the above-mentioned thinning of the carrier 101, where the thickness is measured in a third direction, indicated by "z" in the figures, perpendicular to the first and second directions. If necessary, an electrically insulating layer, for example including or consisting of silicon oxide or silicon nitride, may be applied or formed on the upper surface of the carrier 101.

[0043] As shown, the drive ring 20 is connected to the mirror element 10 via two first torsion spring elements 41 located on opposite sides of the mirror element 10 along a line along a first direction. The drive ring 20 is further connected to the frame element 20 via two second torsion spring elements 42 located on opposite sides of the drive ring 20 along a line along a second direction. Thus, the suspension of the mirror element 10 to the drive ring 20 is rotated by 90° relative to the suspension of the drive ring 20 to the frame element 30.

[0044] The mirror element 10 has a mirror region 11 and an edge region 12 surrounding the mirror region 11. The edge region 12 is partially separated from the mirror region 11 by two openings 13, which are formed by etching during the formation of the mirror element 10 as described above, and thus are preferably at least partially mechanically separated. As shown, the mirror element 10 and the mirror region 11 preferably have a circular basic shape, and the openings 13 are therefore arc-shaped. The two openings 13 are formed opposite each other along a first direction. The edge region 12 is connected to the mirror region 11 via two connection regions 14, so that the two openings 13 are separated from each other by two connection regions 14 located on opposite sides of the mirror region 11 along a second direction, so that the connection regions are aligned rotated 90° relative to the first torsion spring element 41.

[0045] 2C and 2D, a first electrode 51 and a piezoelectric layer 50 are successively applied onto the drive ring 20, the second torsion spring element 42 and partially onto the frame element 30. In order that a portion of the first electrode 51 on the drive ring 20 can be contacted externally via a portion of the first electrode 51 on the frame element 30, contact elements 53 in the form of openings in the piezoelectric layer 50 are provided, as shown in FIG.

[0046] 2E, a second electrode 52 is applied to the drive ring 20 on the piezoelectric layer 50. The second electrode 52 is structured into a plurality of control areas, which may be divided into at least first and second control areas, as will be explained further below, so that the second electrode 52 has a plurality of areas that can be controlled independently of one another. For electrical contact of the control areas of the second electrode 52, further contact areas 53 are applied to the frame element 30, which contact areas 53 are conductively connected to the drive areas via conductive tracks 54, which are also applied to the piezoelectric layer 50.

[0047] 2E, a reflective coating 15, preferably a metal coating, is applied to the mirror region 11. Alternatively, a dielectric coating, such as a Bragg mirror, is also possible. The edge region 12 and the connection region 13 are left without the reflective coating 15.

[0048] The first torsion spring element 41 and the second torsion spring element 42 are designed as so-called torsion beams and have an elongated shape with a longitudinal direction extending along a first direction in the case of the first torsion spring element 41 and along a second direction in the case of the second torsion spring element 42. During operation of the mirror assembly 100, the torsion spring elements 41, 42 can each perform a torsional movement about an axis of rotation, which preferably substantially coincides with the longitudinal direction of the respective torsion spring element 41, 42. When the mirror element 10 is rotated relative to the drive ring 20 about the first axis of rotation defined by the first torsion spring element 41, the first torsion spring element 41 can exert a restoring force on the mirror element 10 that preferably depends linearly on the rotation angle. When the drive ring 20, and therefore the mirror element 10, is rotated relative to the frame element 30 around a second axis of rotation defined by the second torsion spring element 42, the second torsion spring element 42 can exert a restoring force on the drive ring 20 that preferably depends linearly on the angle of rotation.

[0049] On the drive ring 20, the control regions of the first electrode 51, the piezoelectric layer 50, and the second electrode 52 form independently controllable piezoelectric elements. By applying a voltage between at least one control region of the first electrode 51 and the second electrode 52, mechanical deformation of the piezoelectric layer 50, and thus of the drive ring 20 in a partial region, can be achieved by the inverse piezoelectric effect. A force can thereby be applied to the drive ring 20 and / or the mirror element 10. By applying an AC signal with an oscillating voltage, an oscillating force can be exerted, which can induce an oscillating deformation. This can cause at least a portion of the mirror element 100 to enter a vibrational state. Figures 3A and 3B show schematic diagrams of control schemes for method steps of the method for operating the piezoelectric mirror element 100 according to Figures 1A and 1B. For clarity, only the control region of the second electrode is labeled in Figures 3A and 3B. The following reference numbers not shown in Figures 3A and 3B refer to Figures 1A-2E.

[0050] By controlling the first control region 521, referenced in Figure 3A, with a first AC signal having a first frequency, and the first control region 521' with a first AC signal having the first frequency but with a phase position shifted by 180°, the mirror element 10 can be transitioned into a first torsional oscillation relative to the drive ring 20 about the first axis of rotation formed by the first torsion spring element 41. By controlling the second control region 522, referenced in Figure 3B, with a second AC signal having a second frequency, and the second control region 522' with a second AC signal having the second frequency but with a phase position shifted by 180°, the drive ring 20, and therefore the mirror element 10, can be transitioned into a second torsional oscillation relative to the frame element 30 about the second axis of rotation formed by the second torsion spring element 42.

[0051] In particular, the control by the first AC signal and the control by the second AC signal are performed simultaneously, so that the mirror element 10 and the drive ring 20 simultaneously undergo the above-mentioned torsional vibration, so that the mirror element 10 vibrates at a first frequency relative to the drive ring 20 about the first rotation axis, and simultaneously the drive ring 20 vibrates together with the mirror element 10 at a second frequency relative to the frame element 30 about the second rotation axis. The first and second frequencies are particularly preferably resonant frequencies of the torsional vibrations, which depend on the geometric configuration of the elements of the mirror assembly, or frequencies at least close to the respective resonant frequencies. Particularly preferably, the first and second frequencies are different. By arranging the first rotation axis rotated by 90° with respect to the second rotation axis, the first and second torsional vibrations can preferably be mechanically decoupled.

[0052] The different resonant frequencies can be achieved, in particular, by the non-circular design of the illustrated drive ring 40 and by the fact that the first torsional vibration is driven solely by the mirror elements 10, while the second torsional vibration is driven by the drive ring 20 together with the mirror elements 10. As can be seen in FIGS. 1A-2E , the drive ring 20 has a first diameter along a first direction and a second diameter along a second direction, the first diameter being different from the second diameter. In particular, the first diameter in the illustrated embodiment is larger than the second diameter. Particularly preferably, the drive ring 20 has an elliptical shape, or at least a shape approximating an elliptical shape, as shown.

[0053] The drive ring 20 is bounded by an inner edge facing the mirror element 10 and an outer edge opposite the inner edge in a plane spanned by the first and second directions, each of which may have an elliptical shape or at least a shape approximating an elliptical shape. The shape of the outer edge may be defined by the aforementioned first and second diameters, which are the first and second outer diameters of the drive ring 20. The inner edge similarly has first and second diameters, which are the first and second inner diameters of the drive ring 20, with the first inner diameter extending along the first direction and the second inner diameter extending along the second direction, respectively. The ratio between the first outer diameter and the second outer diameter may be the same as or different from the ratio between the first inner diameter and the second inner diameter. When the ratios are different, the drive ring 20 may have a first width along the first direction and a second width along the second direction, as shown. For example, the first width may be smaller than the second width, as shown.

[0054] 4A-5E show simulation studies for the piezoelectric mirror assembly 100 according to the aforementioned figures.

[0055] For this purpose, the following preferred parameters for the mirror components were assumed: - Mirror element diameter: 1.7mm - first outer diameter of the drive ring 20, i.e., the larger outer diameter: 5.7 mm Distance between the ends of the second torsion spring element 42 adjacent to the frame element 30: 6.4 mm - thickness of the moving part of the piezoelectric mirror component, i.e. the element inside the opening 31: 175 μm - Piezoelectric layer thickness: 1 μm - Estimated attenuation: 10 -4 - AC signal voltage: ±2V - square cross section of the torsion spring elements 41, 42, i.e. the thickness is equal to the width - Ignoring ESR (equivalent series resistance)

[0056] Figures 4A and 4B show, in a three-dimensional view and a side view along a first direction, the relative rotation of the mirror element 10 with respect to the drive ring 20 resulting from the control of the first torsional vibration described in relation to Figure 3A.

[0057] Figure 4C shows a diagram for a simulation to investigate the mechanical (top) and electrical (bottom) performance as a function of the first frequency of the applied first AC signal. For the mechanical performance, the mechanical half-scan angle, i.e., the maximum rotation angle of the mirror element from the neutral position to one side achievable by torsional vibration, and the phase delay between the exciting first AC signal and the oscillatory motion of the mirror element, were investigated. For the electrical performance, the magnitude and phase of the complex resistance were investigated. In the graph, arrows indicate which vertical axis corresponds to which curve. As can be seen, the resonant frequency of the first torsional vibration is 28.4 kHz. The diagram shows a pure harmonic vibration without any inherent nonlinear behavior, thus a pure torsional vibration mode; in particular, no hysteresis behavior is observed. The drive ring exhibits only slight, particularly negligible, motion. The optical field of view (FoV) achievable at resonance for the selected parameters is approximately 60°, which corresponds to a mechanical half-scan angle of approximately 15°. By slightly detuning the first frequency from the resonant frequency, a reduction in FoV can be achieved if desired.

[0058] 4D and 4E show, based on simulations, the torsion of the mirror element surface, as indicated by displacement in micrometers, and the mechanical stress of the mirror part in GPa during the first torsional oscillation at the resonance frequency. The torsion of the mirror surface during oscillation ranges from ±250 nm, with the highest value appearing only near the connection region. The stress for a 60° FoV at resonance reaches a maximum of approximately 2.5 GPa in the first torsion spring element. Such a value is acceptable for silicon. By reducing the FoV, for example, by a factor of three to approximately 40°, the torsion and stress can be further reduced, since the magnitude of the two effects is proportional to the scan angle.

[0059] Figures 5A-5E show simulation results for the control of the second torsional vibration described in connection with Figure 3B, corresponding to Figures 4A-4E. Figure 5B shows a view along the second direction compared to Figure 4B. A resonant frequency of 5.85 kHz is generated for the second torsional vibration, which is also a pure torsional vibration mode around the second torsion spring element without hysteresis. The control ring then moves with the mirror element, resulting in a deflection of the laser beam perpendicular to the deflection described in connection with Figures 4A-4E. Consequently, Lissajous scanning is possible with the first and second torsional vibrations. The achievable FoV for the selected parameters is 36°, corresponding to a mechanical half-scan angle of 9°. The twist of the mirror surface during vibration is in the range of ±50 nm, with the highest value occurring only at the edge regions of the mirror element and not at the mirror surface. The stress for a 36° FoV at resonance reaches a maximum of approximately 1.5 GPa in the second torsion spring element, which is within the acceptable range for silicon, resulting in a 36° FoV for the second torsional vibration.

[0060] Table 1 below summarizes the results of the simulations discussed in connection with Figures 4A-5E:

[0061] [Table 1]

[0062] Thus, the first torsion spring element enables a relatively fast pure torsional vibration mode of the mirror element, while the second torsion spring element enables a comparatively slower pure torsional vibration mode of the drive ring with the mirror element, the two vibrations having non-linear behavior and no hysteresis.

[0063] Further embodiments are described in connection with the following figures, which are variations of the mirror components described in connection with the previous figures, and therefore the following description will substantially address deviations from the previous description.

[0064] Figures 6A and 6B show schematic diagrams of a piezoelectric mirror component 100 according to a further embodiment, the views in Figures 6A and 6B corresponding to the views in Figures 1A and 1B. Figures 7A to 7E show schematic diagrams of method steps of a method for manufacturing a piezoelectric mirror component 100 according to Figures 6A and 6B, the views in Figures 7A to 7E corresponding to the views in Figures 2A to 2E. The following description relates equally to Figures 6A and 6B and to Figures 7A to 7E.

[0065] 1A-2E, the mirror element 100 of Figures 6A-7E further comprises an actuation region 33 of the frame element 30 on the frame element 30, which actuation region is surrounded by an edge 32 of the frame element 30. The actuation region 33 is directly adjacent to an opening 31, which may be, for example, hexagonal as shown, and has a smaller thickness than the edge 31, as do the movable components of the mirror element 100 disposed within the opening 31. Furthermore, the actuation region 33 is partially separated from the edge 32 by a plurality of openings 34.

[0066] In addition to the drive ring 20, the second electrode 52 is also applied on the frame element 30 in the actuation area 33 and structured into a plurality of control areas, so that in addition to the control area on the drive ring 20, further control areas can be provided on the frame element 30 by means of which forces can be applied specifically to the drive ring 20 in appropriate control, as further explained below. The larger structure with the illustrated additional actuation area 33 allows additional or alternative actuation for the second torsional oscillation of the drive ring 20 compared to the previous embodiment.

[0067] 6A and 6B, a larger region 102 of the carrier 101 is thinned from its underside, as shown in FIG. 7A. Region 102 corresponds to the region in which the mirror element 10, the piezoelectric drive ring 20, the frame element 30, the torsion spring elements 41 and 42, and the actuation region 33 are located. To form the mirror element 10, the drive ring 20, the torsion spring elements 41 and 42, and the actuation region 33 in region 102, the carrier is etched and structured to create an opening 34 in the frame element 30 in addition to the components in opening 31, as shown in FIG. 7B. The unthinned portion of the frame element 30 surrounding the mirror element 10, the piezoelectric drive ring 20, the torsion spring elements 41 and 42, the actuation region 33, and the opening 34 forms the edge 32, and all of the listed components are integrally formed.

[0068] 7C-7E correspond to the method steps described in connection with Figures 2C-2E, in which a first electrode 51, a piezoelectric layer 50 and a second electrode 52 are also applied in the active area 33 of the frame element 30 to form an additional piezoelectric element. A contact element 53 is separated from the active area 33 by an opening 34 and is arranged on the edge 32, whereby the contact element 53 is at least partially mechanically separated from the active area 33.

[0069] 3A and 3B, each of the control regions of the first electrode 51, piezoelectric layer 50 and second electrode 52 on the drive ring 20 and frame element 30 form piezoelectric elements that can be controlled independently of one another. Figures 8A-8E show schematic diagrams of an exemplary control scheme via first and second control regions 521, 521', 522, 522' for a method for operating a piezoelectric mirror component 100 according to Figures 6A-7E.

[0070] 8A-8C, first control regions 521 and 521' are labeled and are controlled by a first AC signal having a first frequency and first control region 521' by a first AC signal having the first frequency but shifted in phase by 180° to transition the mirror element 10 into a first torsional oscillation relative to the drive ring 20 about a first axis of rotation formed by the first torsion spring element 41. 8D and 8E, second control regions 522 and 522' are correspondingly labeled, and the second control region 522 is controlled by a second AC signal having a second frequency, and the second control region 522' is controlled by a second AC signal having the second frequency but phase-shifted by 180°, in order to transition the drive ring 20, together with the mirror element 10, into a second torsional oscillation relative to the frame element 30 about a second axis of rotation formed by the second torsion spring element 42. In this case, in particular, the control scheme of Figure 8A can be used in combination with the control scheme of Figure 8D, and one of the control schemes of Figures 8B and 8C can be used in combination with the control scheme of Figure 8E, so that the control region of the second electrode 52 can be unambiguously assigned to one of the two torsional oscillations.

[0071] 9A-12E show a simulation study similar to that described in connection with FIGS. 4A-5E, in which, in addition to the preferred parameters employed above in connection with FIGS. 4A-5E, the dimensions of the mirror assembly, including the frame elements, are approximately 11×8 mm. 2 All simulation studies showed a pure torsional vibration mode without hysteresis behavior.

[0072] Figures 9A-9E relate to the control shown in Figure 8A for generating the first torsional vibration. This resulted in a resonant frequency of 24.39 kHz and an FoV of approximately 42°, corresponding to a mechanical half-scan angle of approximately 10.7°. The torsion of the mirror region during vibration was ±23.8 nm, which is sufficiently small for the mechanical stress.

[0073] Figures 10A-10E relate to the control shown in Figure 8B for generating the first torsional vibration. The resonant frequency defined by the mechanical boundary conditions is 24.39 kHz as in Figure 8A, but a FoV of 48° is achieved, which corresponds to a mechanical half-scan angle of 12°. The torsion of the mirror surface during vibration is ±26.8 nm, and the mechanical stress is sufficiently small.

[0074] Figures 11A-11E relate to the control shown in Figure 8D for generating a second torsional vibration. This resulted in a resonant frequency of 4.88 kHz and an FoV of approximately 75°, corresponding to a mechanical half-scan angle of approximately 18.7°. The torsion of the mirror region during vibration was ±7.6 nm, which is sufficiently small for the mechanical stress.

[0075] Figures 12A-12E relate to the control shown in Figure 8E for generating a second torsional vibration. This again results in a resonant frequency of 4.88 kHz and an FoV of approximately 45°, corresponding to a mechanical half-scan angle of approximately 11.4°. The torsion of the mirror region during vibration is ±4.5 nm, which is sufficiently small for the mechanical stress.

[0076] Figures 13A and 13B show schematic diagrams of a piezoelectric mirror element 100 according to a further embodiment, which forms a variant of the mirror element described in relation to Figures 6A to 7E. Figures 14A to 14E show schematic diagrams of method steps of a method for manufacturing the piezoelectric mirror element 100 according to Figures 13A and 13B, which correspond to the method steps described in relation to Figures 7A to 7E. The following description relates equally to Figures 13A and 13B and to Figures 14A to 14E.

[0077] 6A-7E, the embodiment of mirror element 100 shown in Figures 13A-14E has a smaller active area 33 having a rather rectangular shape. Opening 31 is formed in this embodiment as a rectangle, preferably as a square.

[0078] 15 shows a schematic diagram of an exemplary control scheme via second control regions 522, 522′ for the method of operating the piezoelectric mirror assembly 100 according to FIGS. 13A-14E, in which the second control region 522 is controlled by a second AC signal having a second frequency, and the second control region 522′ is controlled by a second AC signal having the second frequency but shifted in phase by 180°, to transition the drive ring 20 together with the mirror element 10 into a second torsional oscillation relative to the frame element 30 about a second axis of rotation formed by the second torsion spring element 42. To generate the first torsional oscillation, for example, the control scheme shown in FIG. 8A may be used.

[0079] Figures 16A-16E show a simulation study similar to that described in connection with Figures 4A-5E, but related to the control shown in Figure 15. The simulation study showed a pure torsional vibration mode without hysteresis behavior for the second torsional vibration investigated. This exhibited a resonant frequency of 5.51 kHz and an FoV of 67°, which corresponds to a mechanical half-scan angle of approximately 17.8°. The twist of the mirror region during vibration was ±7.6 nm, which is sufficiently small for the mechanical stress.

[0080] The above-described piezoelectric mirror assemblies according to some preferred embodiments comprise thin-film piezoelectric elements, by which the mirror elements are driven at resonance in a first direction and a second direction, respectively. The result is a so-called Lissajous scan. This allows for a higher image resolution at the same resonance frequency for the fast deflection axis, i.e., the first rotation axis in the above-described embodiments, compared to a raster scan. The following parameters, resulting from the required image resolution and repetition frequency, can be targeted and adjusted depending on the application: - diameter of the mirror element - The diameter of the mirror as the maximum deflection angular aperture in each orthogonal deflection direction provides diffraction-limited image resolution. - The operating frequency in each direction results in an image resolution and a refresh rate, which can be balanced against each other by fine-tuning the frequency ratio in the two directions. - Mirror flatness at all operating points to avoid aberrations, pixel smear and speckle patterns - The mirror element should oscillate harmonically about both axes of rotation through appropriate selection of the amplitude of the AC signal so that the resonant frequency is amplitude independent to ensure a stable frequency ratio. The resonance of the mirror element should not have too small a bandwidth to allow the fine tuning mentioned above. - Compact design - Shock resistant

[0081] In particular, the mirror element described herein can provide a 2D design that can fully meet all requirements for a resolution of 1024 x 768 pixels. The mirror element can particularly preferably have one or more or all of the following listed properties: - Torsional vibration in two directions to ensure harmonic vibration even for larger amplitudes - Same thickness for all moving parts to avoid high processing costs The two frequencies are clearly different, which allows the suspension of the mirror element in one direction to be optimized, which also allows the thickness to be reduced somewhat. The thickness is derived from the desired mirror element diameter, suspension, desired frequency and required flatness in relation to the material. The dimensioning of the first torsion spring element results from the actual mirror element already defined, from the required frequency and deflection, and from the load capacity of the material. The second torsion spring element is mounted on the outside of the drive ring and is preferably rotated 90° relative to the first torsion spring element. The drive for the second torsional vibration is preferably also on the movable drive ring, which has the advantage of a compact design, but also reduces the frequency due to the moment of inertia of the drive ring.

[0082] Furthermore, the piezoelectric mirror components described herein may have one or more of the following advantages: - Both vibrations are achieved by torsion spring elements, i.e. the vibrations are harmonic, even for high deflections, which avoids the anharmonicities caused by suspension bending in many other designs, such as the so-called "quad pod" designs. - The second torsion spring element for the slower vibration is located on the outside of the drive ring, which moves with it. This allows the drive to be optimized for the first torsional vibration without substantially affecting the characteristics of the second torsional vibration. - Both vibrations can share the drive ring, which results in a very compact design. The elliptical symmetry of the drive ring allows more degrees of freedom, especially for separately adjusting the frequency and deflection angle of the two orthogonal torsional vibrations. For example, the ellipticity of the drive ring can be optimized to obtain the best control of the first torsional vibration.

[0083] In a particularly preferred embodiment, the mirror elements have the following characteristics, whereby a resolution of 1024 x 768 pixels can be achieved, preferably with a full-screen refresh rate of approximately 50 Hz: - Material: Silicone - First electrode metal: platinum - Metal of the second electrode: gold - Metal with reflective coating: Aluminum - Silicon thickness: 175μm - Diameter of the mirror area with reflective coating: 1.7mm - Torsion spring element: width 175 μm, length 1 mm - Drive ring: width 0.7~0.95mm - Material of the piezoelectric layer: PZT with a thickness in the range of 1-2 μm

[0084] In a further particularly preferred embodiment, the mirror element has the following characteristics, whereby a resolution of 1024 x 768 pixels with a full-screen refresh rate of preferably approximately 50 Hz can be achieved: - Material: Silicone - First electrode metal: platinum - Metal of the second electrode: gold - Metal with reflective coating: Aluminum - Silicon thickness: 150μm - Elliptical mirror area with reflective coating - Ellipse axis length of mirror area: 1.6mm x 1.7mm - Torsion spring element: width 150μm, length 0.6~0.8mm - Drive ring: width 0.7~1.35mm - Material of the piezoelectric layer: PZT with a thickness in the range of 1-2 μm

[0085] 17 shows a schematic diagram of a further embodiment of a projection device 1000 comprising a piezoelectric mirror element 100 according to the previous description. Furthermore, the projection device comprises a laser light source 200 which emits laser light 201 during operation.

[0086] For example, the laser light source 200 may be a so-called RGB light source, which can emit red, green, and blue laser light. For this purpose, the laser light source 200 may have, for example, three laser diodes or groups of laser diodes that can be correspondingly modulated. The laser light beams may be superimposed, for example, in a beam combiner 202, so that a combined beam of laser light 201′ can be irradiated onto the piezoelectric mirror element 100 and reflected therefrom into a desired image area. The laser light source 200 may be controlled, for example, via laser control electronics 206, for example, to modulate the amplitude of the laser light over time.

[0087] The piezoelectric mirror assembly 100 may be controlled via mirror assembly control electronics 203, for example, to generate a desired Lissajous figure that can scan a desired image area. Additionally, sensor electronics 204 may be provided to detect the position and / or frequency of the mirror elements of the mirror assembly 100, preferably in real time. Additionally, there may be image processing electronics 205, for example, that controls the overall image display. This may correspond to the conversion of image or film information into control signals for the laser source 200 and mirror assembly 100, including in particular the time synchronization between mirror element position and the amplitudes of the different lasers.

[0088] 18A-18E show schematic diagrams of measures for determining the position and / or frequency of components of a piezoelectric mirror assembly, according to some embodiments. These measures may be provided in association with a method for operating the mirror assembly. For example, such measures may be provided in association with the sensor electronics 204 described above.

[0089] For example, the second frequency can be measured in the first AC signal and the first frequency can be measured in the second AC signal during operation of the piezoelectric mirror assembly 100. As shown in Figure 18A, this can be achieved, for example, by use of a suitable frequency filter 71 in the drive supply line 70, so that no additional line is required.

[0090] 18B and 18C, in addition to the first and second control areas, a third control area 523 can be provided, in which a piezoelectric signal can be measured via the piezoelectric effect. The third control area 523, which can also be called a sensor element or sensor area, can be provided at a suitable position, in particular, so that a good signal can be achieved.

[0091] For example, the third control region 523 may be located on the drive ring 20, for example, near the first torsion spring element 42, or near the second torsion spring element 42 as shown in FIG. 18B. The third control region being located "near the torsion spring element" may particularly mean that the third control region is located near or adjacent to the origin of the torsion spring element, and that the first and second control regions are not located closer to the torsion spring element than the third control region. In FIG. 18B, four third control regions 523 are provided, purely by way of example, and are arranged symmetrically with respect to the first and second torsion spring elements 42.

[0092] Furthermore, the third control area 523 can also be formed on the frame element 30, as shown in Figure 18C. This can achieve that the drive ring 20 is fully accessible to the control areas 521, 521', 522, 522' during operation. Furthermore, the third control area 523 on the frame element 30 can be more easily manufactured and more easily contactable, since additional conductive paths 54 for these contacts do not have to be routed through the second torsion spring element 42.

[0093] 18C, for example, four third control regions 523 as sensor elements Sa, Sb, Sc, Sd may be arranged symmetrically with respect to the first and second torsion spring elements 42. Via contact elements 53a, 53b, 53c, 53d and conductive paths 54, the sensor elements Sa, Sb, Sc, Sd may be contacted.

[0094] For example, as shown, two third control areas 523 forming sensor elements Sa and Sb can be arranged at the base of one of the two second torsion spring elements 42, and two further third control areas 523 forming sensor elements Sc and Sd can be arranged at the base of the other of the two second torsion spring elements 42, symmetrically with respect to the axis formed by the second torsion spring elements 42. The frame element 30 can be thinned below the second control areas 523 to allow mechanical mobility of the third control areas 523, and in particular can have, for example, the same thickness as the drive ring 20. For example, the frame element 30 can have a reduced thickness, i.e., the same thickness as the drive ring 20, in the hatched area 35 where the third control elements 523 are arranged, while the remainder of the frame element 30 or at least the edges of the frame element can have a greater thickness than the area 35, as described above. In other words, the third control region is preferably located in one or more regions of the frame element 30 that have a smaller thickness compared to the remainder of the frame element 30 or at least compared to the edges of the frame element 30.

[0095] The above-described arrangement of the sensor elements Sa, Sb, Sc and Sd on the frame element 30 allows deflections in two directions to be detected simultaneously, i.e. deflections about the first torsion element 41 and deflections about the second torsion element 42. For this purpose, a linear combination of the signals of the four sensor elements Sa, Sb, Sc, Sd formed by the third control area 523 can be used. If for simplicity the signals of the sensor elements are also referred to as Sa, Sb, Sc, and Sd, then the vibration about the first torsion spring element 41 can be determined by one or more of the linear combinations |Sa+Sb|, |Sc+Sd|, |Sa-Sc|, and |Sb-Sd| of the signals of the sensor elements Sa, Sb, Sc, and Sd, respectively, and the deflection about the second torsion spring element 42 can be determined by one or more of the linear combinations |Sa+Sc|, |Sb+Sd|, |Sa-Sb|, and |Sc-Sd| of the signals of the sensor elements Sa, Sb, Sc, and Sd, respectively. Using more than one of the listed linear combinations can increase the measurement accuracy. Alternatively, for example, only two third control regions 523 can be present, since these are in principle sufficient to obtain the desired information. For example, there may be only a third control region 523 forming sensor elements Sa and Sb, or forming sensor elements Sa and Sc, or forming sensor elements Sc and Sd, or forming sensor elements Sb and Sd. In other words, if there are only two sensor elements, the two sensor elements should not be arranged diagonally to each other, but should be arranged on the same side with respect to the first torsion spring element 41 or the second torsion spring element 42.

[0096] Furthermore, it is possible to have first and / or second control regions that are alternately used in a time-division multiplexed manner to drive the mirror elements or drive rings and to measure the piezoelectric signal. For this purpose, as shown in FIG. 18C, for example, there can be at least several first or second control regions 521, 521', 522, 522', which simultaneously function as a third control region. This can mean, in particular, that the driving and position determination are performed at different times. This can be achieved, for example, by suitable pulse-width modulation, whereby the mirror elements are alternately driven for a predetermined number of periods and then measured for a smaller number of periods. Due to the high mechanical quality, only a small amount of deflection of the mirror elements is lost.

[0097] Furthermore, for position measurement and / or frequency measurement, at least two electrode elements 61, 61', 62, 62' may be present, as shown in FIG. 18D . The electrode elements form a capacitor that exhibits a variable capacitance when the mirror element 10 or the drive ring 20 moves, and the capacitance of the capacitor is measured. The electrode elements 61, 61', 62, 62' may be formed, for example, by conductive path sections. The first electrode element 61 may be arranged, for example, on the frame element 30, and the second electrode element 62 may be arranged adjacent to the first electrode element 61 on the drive ring 20. When the drive ring 20 moves relative to the frame element 30, the distance between the electrode elements 61, 62 may change, which may change the capacitance of the capacitor formed by the electrode elements 61, 62. Correspondingly, further electrode elements may be arranged, for example, on the drive ring 20 and the mirror element 10.

[0098] For example, it is also possible to arrange two electrode elements 61', 62' on either side of the drive ring 20 on the frame element 30. The drive ring 20 can then act like a dielectric that moves between the electrode elements 61', 62' during movement. Correspondingly, two electrode elements can also be arranged on the drive ring 20 on either side of the mirror element 10.

[0099] Such a capacitive measurement may also determine the zero crossings, in particular of the drive ring 20 and / or the mirror element 10. In order to avoid capacitive short circuits, the first electrode may be structured appropriately.

[0100] In connection with the aforementioned figures, a circular mirror region 11 is shown throughout. Alternatively, the mirror region 11, and therefore also the reflective coating 15, can be elliptical, as shown in the cross-sectional views of the mirror element in FIGS. 19A and 19B, with a larger ellipse axis G and a smaller ellipse axis K. Preferably, the larger ellipse axis G is oriented along a first direction and the smaller ellipse axis K is oriented along a second direction, as shown in FIG. 19A. Alternatively, the larger ellipse axis G can be oriented along the second direction and the smaller ellipse axis K can be oriented along the first direction, as shown in FIG. 19B. The opening 13 has the shape of an elliptical arc in the case of an elliptical mirror region 11. The ratio of the larger ellipse axis G to the smaller ellipse axis K can be, for example, greater than 1, or 1.02 or more, or 1.04 or more, or 1.06 or more, and 1.1 or less, or 1.08 or less, or 1.07 or less.

[0101] The features and embodiments described in connection with the drawings can be combined with each other according to further embodiments, even if not all combinations are explicitly described. Furthermore, the embodiments described in connection with the drawings can alternatively or additionally have further features according to the description in general part.

[0102] The present invention is not limited by the description based on the examples, but rather includes all novel features and all combinations of features, including all combinations of features in the claims, even if the feature or combination itself is not explicitly set out in the claims or examples. [Explanation of symbols]

[0103] 10 mirror element 11 Mirror Area 12 Edge Area 13 Opening 14 Connection Area 15 Reflective Coating 20 Drive ring 30 Frame Elements 31 Opening 32 Edge 33 Operating Area 34 Opening 35 areas 41 First torsion spring element 42 Second torsion spring element 50 Piezoelectric layer 51 First electrode 52 Second electrode 521,521' First control region 522,522' Second control region 523 Third Control Zone 53,53a,53b,53c,53d Contact elements 54 Conductive Path 61,61' electrode element 62,62' electrode element 70 Conductor 71 Frequency Filter 100 Piezoelectric mirror parts 101 Career 102 areas 200 laser light source 201,201' laser light 202 Beam Combiner 203 Mirror component control electronics 204 Control Electronic Equipment 205 Image processing electronic devices 206 Laser Control Electronic Equipment 1000 projection equipment G,K Elliptical axis Sa, Sb, Sc, Sd sensor element

Claims

1. A piezoelectric mirror component (100), comprising: A mirror element (10); a drive ring (20) surrounding the mirror element and connected to the mirror element via at least one first torsion spring element (41); a frame element (30) connected to the drive ring via at least one second torsion spring element (42); Equipped with a first electrode and a second electrode structured into a plurality of control regions are applied to the drive ring, and a piezoelectric layer is disposed between the first electrode and the second electrode; the first electrode and the piezoelectric layer are applied at least partially onto the frame element, the second electrode is applied within an active area of ​​the frame element surrounded by an edge, the active area having a smaller thickness than the edge; A piezoelectric mirror component (100).

2. 2. The piezoelectric mirror assembly (100) of claim 1, wherein the drive ring has a first diameter along a first direction and a second diameter along a second direction perpendicular to the first diameter, the first diameter being larger than the second diameter.

3. 3. A piezoelectric mirror assembly according to claim 1, wherein the active area is partially separated from the edge by at least one opening.

4. 4. The piezoelectric mirror assembly of claim 3, wherein the active region is partially separated from the edge by a plurality of openings.

5. 3. The piezoelectric mirror assembly according to claim 1, wherein the frame element surrounds the drive ring and has an opening passing through the frame element, the drive ring and the at least one second torsion spring element being disposed within the opening.

6. 6. The piezoelectric mirror assembly according to claim 5, wherein the opening has a basic polygonal shape, such as a hexagon or an octagon.

7. 3. The piezoelectric mirror assembly according to claim 1, wherein the drive ring has an elliptical shape.

8. 3. The piezoelectric mirror assembly according to claim 1, wherein the at least one first torsion spring element is arranged along the first direction, and the at least one second torsion spring element is arranged along the second direction.

9. 3. The piezoelectric mirror assembly according to claim 1, wherein the drive ring is connected to the mirror element via two first torsion spring elements arranged on either side of the mirror element along a straight line, and the drive ring is connected to the frame element via two second torsion spring elements arranged on either side of the drive ring along a straight line.

10. - the mirror element has a mirror area and an edge area surrounding the mirror area, the edge area being partially separated from the mirror area by two openings; - the edge region is connected to the mirror region via two connection regions; 3. The piezoelectric mirror component according to claim 1.

11. 7. The piezoelectric mirror assembly of claim 6, wherein a reflective coating is applied over the mirror area, and the edge area and the connection area are free of the reflective coating.

12. 7. The piezoelectric mirror component according to claim 6, wherein the mirror region is formed in a circular or elliptical shape.

13. 3. The piezoelectric mirror assembly according to claim 1, wherein the mirror element and the drive ring have a thickness smaller than at least one edge of the frame element.

14. 3. The piezoelectric mirror assembly according to claim 1, wherein the frame element, the drive ring, the mirror element, and the torsion spring element are integrally formed.

15. - on said frame element there are contact elements for controlling said first and second electrodes, a control region of the second electrode is connected to a contact element via a conductive path extending over the at least one second torsion spring element; The piezoelectric mirror component according to claim 11 .

16. 3. A piezoelectric mirror assembly according to claim 1 or 2, wherein there are at least two electrode elements, said electrode elements forming a capacitor exhibiting a variable capacitance when said mirror element or said drive ring moves.

17. 3. The piezoelectric mirror component according to claim 1, wherein at least two third control regions (523) are arranged on the frame element on the same side with respect to the at least one first torsion spring element or the at least one second torsion spring element.

18. 18. The piezoelectric mirror component of claim 17, wherein the third control region is arranged in one or more regions (35) of the frame element, the regions having a reduced thickness compared to at least one edge of the frame element.

19. 3. A piezoelectric mirror assembly according to claim 1 or 2, wherein means are provided for determining the position of the mirror element and / or the position of the drive ring and / or the frequency of the torsional vibration.

20. 3. A method for operating a piezoelectric mirror component as claimed in claim 1 or 2, wherein the mirror element (10) is transitioned to a first torsional vibration by a first electrical AC signal having a first frequency and acting on a first control area (521, 521'), and the drive ring (20) is transitioned to a second torsional vibration by a second electrical AC signal having a second frequency and acting on a second control area (522, 522').

21. 21. The method of claim 20, wherein the second frequency is measured in the first AC signal and the first frequency is measured in the second AC signal during operation of the piezoelectric mirror component.

22. 21. The method of claim 20, wherein there is a third control region (523), and the piezoelectric signal is measured in the third control region.

23. 21. The method of claim 20, wherein there are at least two electrode elements, the electrode elements forming a capacitor that exhibits a variable capacitance as the mirror element or the drive ring moves, and wherein the capacitance of the capacitor is measured.

24. 21. The method of claim 20, wherein there are first and / or second control regions, the first and / or second control regions being alternately used in a time division multiplexed manner to drive the mirror element or the drive ring and to measure a piezoelectric signal.

25. a laser light source (200); A piezoelectric mirror component (100) according to claim 1 or 2, A projection device (1000) comprising:

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