Piezoelectric mirror component, method for operating a piezoelectric mirror component, and projection device comprising a piezoelectric mirror component - Patents.com

Abstract

A piezoelectric mirror component (100) is presented, 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), and a frame element (30) connected to the drive ring via at least one second torsion spring element (42), the drive ring having a first diameter along a first direction and a second diameter along a second direction perpendicular to the first diameter, the first diameter being greater than the second diameter. Furthermore, a method for operating the piezoelectric mirror component and a projection apparatus are presented.

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 pictures, for example in cinemas, for home theater applications or for mobile display applications. Particularly preferably, cheap and vibration-resistant projectors should be available for this. Furthermore, projectors are used more and more frequently in the automotive field, for example for projecting information on the road surface, for matrix lighting or also for applications based on the LIDAR principle (LIDAR: "Light Detection and Ranging"). For such application areas, a large depth of field is required, which laser projectors can provide. Besides, 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 comprise a rotatable mirror, by which the time-modulated laser beam is deflected. In this way, an image is generated in the far field perceived by the observer, so that the projected image is always in focus for the observer and no eye accommodation is required. In the case of AR / VR glasses, the deflected beam is coupled, for example, into a wave guide lens. Here, the direction of the beam, not its position, determines the position of the image point for the observer, so that no further optics are required. Often, two mirrors are used, one for each orthogonal deflection direction, whereby the laser beam scans the image area in an orthogonal grid. Alternatively, there are solutions using laser arrays, LED arrays (LED: Light Emitting Diode) or QLED arrays (QLED: Quantum Dot Light Emitting Diode), which are limited in their resolution and brightness, and there are also solutions in which the laser light is selectively reflected by a passive panel, which is 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 allowing one-dimensional scanning. Non-patent document 2 describes a rectangular mirror that can move in two dimensions, in one direction the movement is anharmonic in the so-called rocking mode. Non-patent document 1 and non-patent document 3 describe a symmetrically suspended mirror that can move around two axes, the movement around both axes being similar, which may result in undesirable coupling behavior. Non-patent document 4 likewise describes a mirror that can move around two axes, in which the actuator for one of the rotational movements has a large meandering structure, which structure is not very compact, allows only low resonance frequencies and may be sensitive to shocks. Non-patent document 5 describes an electromagnetically actuated mirror. [Prior art documents] [Chartered documents]

[0005]

Patent Document 1

Non-licensed literature

[0006]

Non-licensed literature 1

Non-licensed Document 2

Non-licensed Document 4

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

[0008] These objects are achieved 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 are further evident from the following description and the drawings.

[0009] According to at least one embodiment, a piezoelectric mirror component, which may hereinafter also be called 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 may be aligned in particular along a plane in the rest state of the mirror component.

[0010] A piezoelectric layer is applied at least on the drive ring, the piezoelectric layer being arranged between the first electrode and the second electrode. The piezoelectric layer may comprise one or more piezoelectric materials. Particularly preferably, the piezoelectric layer comprises 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 areas. This means that the second electrode may have a plurality of areas that are controllable independently of one another. The first electrode and / or the piezoelectric layer may be applied continuously or at least partially structured. Thus, on the drive ring, preferably the first electrode and the second electrode structured into a plurality of control areas are applied, with the piezoelectric layer being arranged 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 the first electrode and at least one control area of ​​the second electrode, a mechanical deformation of the piezoelectric layer and thus of the drive ring in a partial area can be achieved by the inverse piezoelectric effect. Thereby, a force can be applied to the drive ring and / or the mirror element. Thus, each of the control areas can form a piezoelectric element together with the piezoelectric layer and the first electrode, by means of which a partial area of ​​the mirror component can be moved. By applying an alternating current signal having an oscillating voltage, an oscillating force may be exerted, which may induce an oscillating deformation, such that at least a portion of the mirror part may be transitioned 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 the movement of the mirror part, which axis of rotation preferably substantially coincides with the longitudinal direction of the beam.

[0013] The 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 area of ​​the second electrode by a first alternating signal having a first frequency, the mirror element can be brought into a first rotational oscillation having a first frequency, and a restoring force, preferably linearly dependent on the rotation angle, can be caused to be applied to the mirror element via the at least one first torsion spring element. Such a rotational oscillation in the at least one torsion spring element is also referred to as a torsional oscillation in the following. The first rotational oscillation can therefore 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 axis of rotation. When the frame element and the drive ring are rotated relative to each other about the second axis of rotation, 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 area of ​​the second electrode by a second alternating signal having a second frequency, the drive ring can be brought into 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 together with the drive ring can perform a second rotational oscillation. The above-mentioned second rotational oscillation can also be called a second torsional oscillation.

[0015] Particularly preferably, the first and second torsion spring elements are arranged rotated by 90° relative to one another, 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 one another, whereby it can be achieved that the first and second torsional vibrations are as independent of one another as possible.

[0016] According to a further embodiment, the first electrode is also applied at least partially onto the frame element. Furthermore, a piezoelectric layer may also be applied at least partially onto the frame element. In addition, a second electrode may also be applied at least partially onto the frame element. Furthermore, a first electrode and / or a piezoelectric layer may also be applied onto the at least one second torsion spring element. 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 surrounded by an edge of the frame element. Thereby, in addition to the control area on the drive ring, further control areas can be provided on the frame element, by means of which forces can be applied, for example, to the drive ring, in an appropriate control.

[0018] Furthermore, there may be contact elements on the frame element, for example on the edges of the frame element, for controlling the first and second electrodes. 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 run over at least one second torsion spring element. Alternatively, it is also possible to omit the conductive paths and bond directly onto the electrodes, thereby avoiding possible parasitic resistances and capacitances associated with conductive paths.

[0019] In the method for operating a piezoelectric mirror component, as described above, the mirror element is preferably brought into a first torsional oscillation by a first alternating signal having a first frequency acting on a first control area. The drive ring, preferably together with the mirror element, is brought into a second torsional oscillation by a second electrical alternating signal having a second frequency acting on a second control area. In particular, the control by the first alternating signal and the control by the second alternating signal can be performed simultaneously. As a result, in particular the mirror element can perform two torsional oscillations simultaneously, the mirror element oscillating relative to the drive ring about a first axis of rotation with a first frequency and the drive ring oscillating together with the mirror element about a second axis of rotation with a second frequency relative to the frame element. The first and second frequencies may in particular be resonant frequencies or may be in the vicinity of the respective resonant frequencies, which may depend on the respective vibrating parts of the mirror component and their geometrical configuration. In particular preferably, 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 component. The mirror component can deflect the laser light emitted by the laser light source during operation. 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 component. Particularly preferably, so-called Lissajous scanning can be achieved in resonant or near-resonant torsional vibrations about a first rotation axis and about a second rotation axis, which are particularly preferably perpendicular to each other.

[0021] The features and embodiments mentioned above and described below apply equally to the piezoelectric mirror component, to the method for operating the piezoelectric mirror component, and to the projection device comprising the piezoelectric mirror component.

[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 elements and an opposite outer edge 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 approximate 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 a first and second diameter, which may also be called the first and second inner diameters, the first inner diameter extending along the first direction and the second inner diameter extending along the second direction, respectively. The ratio of the first outer diameter to the second outer diameter may be the same as or different from the ratio of the first inner diameter to the second inner diameter. If the ratio is different, it may mean that the drive ring has a first width along the first direction and a second width along the second direction, the first width being 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 a first direction and at least one second torsion spring element is arranged along a 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 straight 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 straight 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 connection with 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, whereas the drive ring may be particularly preferably connected to the frame element 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. As a result, at least one opening may have the shape of a circular arc. Particularly preferably, there may be two openings opposite each other and both having the shape of a circular arc.

[0026] Furthermore, the mirror area 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 a second direction and the smaller elliptical axis may be oriented along a first direction. The opening has the shape of an elliptical arc in the case of an elliptical mirror area. 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 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 onto the mirror area. For example, the coating may be a metal coating. Furthermore, a dielectric coating, for example a Bragg mirror, is also possible. The edge area and the connection area may preferably remain free of a reflective coating.

[0029] According to a further embodiment, the frame element surrounds the drive ring. The frame element may in particular have an opening through it, 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 in the drive ring are arranged. The at least one second torsion spring element particularly preferably protrudes into the opening from an edge face 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, it is possible for the opening to have the same extent along the first and second directions. If the frame element has an actuation area, this may adjoin directly 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 in particular mean 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 preferably also have a smaller thickness than the frame portion of the frame element.

[0031] Particularly preferably, the frame elements, the drive ring, the mirror elements and the torsion spring elements are formed in one piece. In particular, the frame elements, the drive ring, the mirror elements and the 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 prepared. The carrier is correspondingly structured to form the frame elements, the drive ring, the mirror elements and the torsion spring elements. On the structured carrier, the electrodes and the piezoelectric layer and, depending on the design, for example an insulating layer and / or a conductive track can then be formed or applied.

[0032] According to further embodiments, means are provided for achieving a position determination of the mirror element and / or a position determination of the drive ring and / or a frequency determination of one or both of the torsional vibrations. For example, during operation of the piezoelectric mirror part, the second frequency can be measured in the first alternating signal and the first frequency in the second alternating signal. This can be achieved, for example, by the use of suitable 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 in a suitable position, in particular so that a good signal can be achieved.

[0033] Furthermore, for the position measurement and / or the frequency measurement, 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 track sections. A first electrode element may be arranged, for example, on the frame element, while a second electrode element is arranged 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, which may change the capacitance of the capacitor formed by the electrode elements. Correspondingly, for example, the electrode elements may be arranged on the drive ring and the mirror element. For example, it is also possible to arrange two electrode elements on opposite sides of the drive ring on the frame element, such that the drive ring is between two electrode elements arranged on the frame element. The drive ring can then act like a moving dielectric between the electrode elements when moving, which may change the capacitance of the capacitor formed thereby. Correspondingly, the two electrode elements may also be arranged on opposite sides of the mirror element on the drive ring.

[0035] Furthermore, there may be a first and / or a 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 emerge from the exemplary embodiments described below in conjunction with the drawings. [Brief description 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 diagram of method steps of a method for manufacturing a piezoelectric mirror component according to FIGS. 1A and 1B; [Figure 2B] 1C is a schematic diagram of method steps of a method for manufacturing a piezoelectric mirror component according to FIGS. 1A and 1B; [Figure 2C] 1C is a schematic diagram of method steps of a method for manufacturing a piezoelectric mirror component according to FIGS. 1A and 1B; [Figure 2D] 1C is a schematic diagram of method steps of a method for manufacturing a piezoelectric mirror component according to FIGS. 1A and 1B; [Figure 2E] 1C is a schematic diagram of method steps of a method for manufacturing a piezoelectric mirror component according to FIGS. 1A and 1B; [Figure 3A] 1C is a schematic diagram of method steps of a method for operating a piezoelectric mirror component according to FIGS. 1A and 1B; [Figure 3B] 1C is a schematic diagram 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] 4 is a schematic diagram of a piezoelectric mirror component according to a further embodiment; [Figure 6B] 4 is a schematic diagram of a piezoelectric mirror component according to a further embodiment; [Figure 7A] 5A and 5B are schematic diagrams of method steps of a method for manufacturing a piezoelectric mirror component according to FIGS. 6A and 6B. [Figure 7B] 5A and 5B are schematic diagrams of method steps of a method for manufacturing a piezoelectric mirror component according to FIGS. 6A and 6B. [Figure 7C] 5A and 5B are schematic diagrams of method steps of a method for manufacturing a piezoelectric mirror component according to FIGS. 6A and 6B. [Figure 7D] 5A and 5B are schematic diagrams of method steps of a method for manufacturing a piezoelectric mirror component according to FIGS. 6A and 6B. [Figure 7E] 5A and 5B are schematic diagrams of method steps of a method for manufacturing a piezoelectric mirror component according to FIGS. 6A and 6B. [Figure 8A] 6C is a schematic diagram of method steps of a method for operating a piezoelectric mirror component according to FIGS. 6A and 6B. FIG. [Figure 8B]6C is a schematic diagram of method steps of a method for operating a piezoelectric mirror component according to FIGS. 6A and 6B. FIG. [Figure 8C] 6C is a schematic diagram of method steps of a method for operating a piezoelectric mirror component according to FIGS. 6A and 6B. FIG. [Figure 8D] 6C is a schematic diagram of method steps of a method for operating a piezoelectric mirror component according to FIGS. 6A and 6B. FIG. [Figure 8E] 6C is a schematic diagram of method steps of a method for operating a piezoelectric mirror component according to FIGS. 6A and 6B. FIG. [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] 4 is a schematic diagram of a piezoelectric mirror component according to a further embodiment; [Figure 13B] 4 is a schematic diagram of a piezoelectric mirror component according to a further embodiment; [Figure 14A] 13C is a schematic diagram of method steps of a method for manufacturing a piezoelectric mirror component according to FIGS. 13A and 13B. [Figure 14B] 13C is a schematic diagram of method steps of a method for manufacturing a piezoelectric mirror component according to FIGS. 13A and 13B. [Figure 14C] 13C is a schematic diagram of method steps of a method for manufacturing a piezoelectric mirror component according to FIGS. 13A and 13B. [Figure 14D] 13C is a schematic diagram of method steps of a method for manufacturing a piezoelectric mirror component according to FIGS. 13A and 13B. [Figure 14E] 13C is a schematic diagram of method steps of a method for manufacturing a piezoelectric mirror component according to FIGS. 13A and 13B. [Figure 15] 13C is a schematic diagram of method steps of a method for operating a piezoelectric mirror component according to FIGS. 13A and 13B. FIG. [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] 4 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 PREFERRED EMBODIMENTS

[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 with respect to each other 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] Figures 1A and 1B show schematic diagrams of a piezoelectric mirror component 100 according to an embodiment, with Figure 1A showing a three-dimensional view of the upper side of the mirror component 100 and Figure 1B showing a three-dimensional view of the lower side of the mirror component 100. Figures 2A-2E show schematic diagrams of method steps of a method for manufacturing the piezoelectric mirror component 100 according to Figures 1A and 1B in a top view. The following description relates equally to Figures 1A and 1B and to Figures 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 it 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, the drive ring 20 and the frame element 30 as well as the torsion spring elements 41, 42 are aligned, in the rest state of the mirror assembly 100, along a plane spanned by a first direction, indicated by "x" in the figures, and a second direction perpendicular to the first direction, indicated by "y" in the figures. On at least the drive ring 20 is applied a piezoelectric layer 50 arranged 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, for example in the form of a silicon wafer or in the form of 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 the underside in the area 102 in which 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 area in which 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 area 102, the carrier is through-etched and thereby structured, as shown in Fig. 2B, so that in the frame element 30 surrounding the drive ring 20 an opening 31 is generated 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 formed in one piece. The opening 31 preferably has a polygonal basic shape, which may be octagonal as shown. It is further 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, perpendicular to the first and second directions, indicated as "z" in the figures. 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 arranged on opposite sides of the mirror element 10 along a line along a first direction. Furthermore, the drive ring 20 is connected to the frame element 20 via two second torsion spring elements 42 arranged 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 comprises a mirror area 11 and an edge area 12 surrounding the mirror area 11, the edge area 12 being partially separated from the mirror area 11 by two openings 13 produced by etching within the framework of the formation of the mirror element 10 as described above, and therefore preferably at least partially mechanically separated. The mirror element 10 and the mirror area 11 have a preferably circular basic shape as shown, so that the openings 13 have the shape of a circular arc. The two openings 13 are formed opposite each other along a first direction. The edge area 12 is connected to the mirror area 11 via two connection areas 14, so that the two openings 13 are separated from each other by two connection areas 14 arranged on opposite sides of the mirror area 11 along a second direction, so that the connection areas are aligned rotated by 90° with respect to the first torsion spring element 41.

[0045] As can be seen in Figures 2C and 2D, successively applied onto the drive ring 20, the second torsion spring element 42 and partially onto the frame element 30 are a first electrode 51 and a piezoelectric layer 50. In order that a part of the first electrode 51 on the drive ring 20 can be contacted from the outside via a part of the first electrode 51 on the frame element 30, a contact element 53 in the form of an opening in the piezoelectric layer 50 is provided, as shown in Figure 2D.

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

[0047] 2E, a reflective coating 15, preferably a metallic coating, is applied onto the mirror area 11. Furthermore, a dielectric coating, e.g. a Bragg mirror, is also possible. The edge area 12 and the connection area 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 a 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 angle of rotation. When the drive ring 20, and thus 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 rotation angle.

[0049] On the drive ring 20, the control areas of the first electrode 51, the piezoelectric layer 50 and the second electrode 52 form piezoelectric elements that can be controlled independently of one another. By applying a voltage between at least one control area of ​​the first electrode 51 and the second electrode 52, a mechanical deformation of the piezoelectric layer 50 and thus of the drive ring 20 in a partial area can be achieved by the inverse piezoelectric effect. Thereby, a force can be applied to the drive ring 20 and / or the mirror element 10. By applying an alternating signal with an oscillating voltage, an oscillating force can be exerted, which force can cause an oscillating deformation. Thereby, at least a part of the mirror element 100 can be brought into a vibration state. Figures 3A and 3B show schematic diagrams of a control scheme for the method steps of the method for operating the piezoelectric mirror element 100 according to Figures 1A and 1B. For clarity, in Figures 3A and 3B only the control area of ​​the second electrode is labeled with a reference number. The following reference numbers not shown in Figures 3A and 3B refer to Figures 1A-2E.

[0050] By controlling the first control area 521, referenced in Fig. 3A, with a first alternating signal having a first frequency and the first control area 521' with a first alternating 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 a first axis of rotation formed by the first torsion spring element 41. By controlling the second control area 522, referenced in Fig. 3B, with a second alternating signal having a second frequency and the second control area 522' with a second alternating signal having a second frequency but with a phase position shifted by 180°, the drive ring 20, and thus the mirror element 10, can be transitioned 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.

[0051] In particular, the control by the first alternating signal and the control by the second alternating 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 oscillates with respect to the drive ring 20 about the first axis of rotation at a first frequency and at the same time the drive ring 20 together with the mirror element 10 oscillates with respect to the frame element 30 about the second axis of rotation at a second frequency. The first and second frequencies can particularly preferably be resonant frequencies of the torsional vibrations depending on the geometrical configuration of the elements of the mirror part or at least close to the respective resonant frequencies. Particularly preferably, the first and second frequencies are different. Due to the arrangement of the first axis of rotation rotated by 90° with respect to the second axis of rotation, 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 drive ring 40 as shown and by the fact that the first torsional vibration is only performed by the mirror element 10, while the second torsional vibration is performed by the drive ring 20 together with the mirror element 10. The drive ring 20 has a first diameter along a first direction and a second diameter along a second direction, as can be seen in Figs. 1A-2E, 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 opposite outer edge in a direction along a plane spanned by the first and second directions, each of which may have an elliptical shape or at least approximate 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 likewise has first and second diameters, which are the first and second inner diameters of the drive ring 20, the first inner diameter extending along the first direction and the second inner diameter extending along the second direction, respectively. The ratio of the first outer diameter to the second outer diameter may be the same as or different from the ratio of the first inner diameter to the second inner diameter. If 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, where the first width is different from the second width. For example, the first width may be less than the second width, as shown.

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

[0055] For this purpose, the following preferred parameters for the mirror components were assumed: - Mirror element diameter: 1.7mm - the first, i.e. larger, outer diameter of the drive ring 20: 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: 1μm - Expected attenuation: 10 -4 - AC signal voltage: ±2V - the torsion spring elements 41, 42 have a square cross section, 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 in 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] In FIG. 4C, diagrams for simulations to investigate the mechanical (upper diagram) and electrical (lower diagram) performance as a function of the first frequency of the applied first alternating signal are shown. 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 alternating signal and the vibrational motion of the mirror element, were investigated. For the electrical performance, the magnitude and phase of the complex resistance were investigated. In the graph, it is indicated by arrows which vertical axis relates to which curve. As can be seen, the resonance frequency of the first torsional vibration is 28.4 kHz. The diagram shows a pure harmonic vibration without essential nonlinear behavior, thus a pure torsional vibration mode, and in particular no hysteretic behavior is observed. The drive ring shows only a small, in particular negligible, movement. The optical field of view (FoV) achievable at resonance for the selected parameters is about 60°, which corresponds to a mechanical half-scan angle of about 15°. By slightly detuning the first frequency from the resonant frequency, a reduction in FoV can be achieved if desired.

[0058] In Figures 4D and 4E, based on simulations, the torsion of the surface of the mirror element, represented by the displacement in micrometers, and the mechanical stress of the mirror part in GPa during the first torsional oscillation at the resonance frequency are shown. The torsion of the mirror surface during oscillation is in the range of ±250 nm, with the highest values ​​appearing only in the vicinity of the connection area. The stress for a FoV of 60° at resonance reaches a maximum value of about 2.5 GPa in the first torsion spring element. Such values ​​are acceptable for silicon. By decreasing the FoV, for example by a factor of 3 to about 40°, the torsion and the stress can be further reduced, since the magnitude of the two effects is proportional to the scan angle.

[0059] In Fig. 5A-5E, corresponding to Fig. 4A-4E, the simulation results of the control of the second torsional vibration described in relation to Fig. 3B are shown, and in Fig. 5B, the view along the second direction is shown in comparison with Fig. 4B. A resonant frequency of 5.85 kHz arises for the second torsional vibration, which is likewise a pure torsional vibration mode around the second torsion spring element, which does not have a hysteresis behavior. The control ring then moves together with the mirror element, so that a deflection of the laser beam perpendicular to the deflection described in relation to Fig. 4A-4E can be achieved, so that by the first and second torsional vibrations, a Lissajous scan is possible. The achievable FoV at the selected parameters is 36°, which corresponds to a mechanical half-scan angle of 9°. The twist of the mirror surface during the vibration is in the range of ±50 nm, with the highest values ​​occurring only in the edge regions of the mirror element and not on the mirror surface. The stress for a 36° FoV at resonance reaches a maximum value of about 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 once again 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 relation to the following figures, which are variations of the mirror components described in relation to the previous figures, and the following description therefore substantially refers to deviations from the previous description.

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

[0065] 1A-2E, the mirror part 100 of Figs. 6A-7E further comprises an active area 33 of the frame element 30 on the frame element 30, which is surrounded by an edge 32 of the frame element 30. The active area 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 is the movable component of the mirror part 100 arranged in the opening 31. Furthermore, the active area 33 is partially separated from the edge 32 by a number 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, whereby 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 suitable control as further explained below. The larger structure with the illustrated additional actuation area 33 allows an additional or alternative drive for the second torsional oscillation of the drive ring 20 compared to the previous embodiment.

[0067] As shown in Fig. 7A, to manufacture the mirror component 100 shown in Fig. 6A and 6B, a larger area 102 of the carrier 101 is thinned from the underside. The area 102 then corresponds to the area in which the mirror element 10, the piezoelectric drive ring 20, the frame element 30, the torsion spring elements 41, 42 and the actuation area 33 are arranged. To form the mirror element 10, the drive ring 20, the torsion spring elements 41, 42 and the actuation area 33 in the area 102, the carrier is etched and structured in such a way that an opening 34 is created in the frame element 30 in addition to the components in the opening 31, as shown in Fig. 7B. The non-thinned part of the frame element 30 surrounding the mirror element 10, the piezoelectric drive ring 20, the torsion spring elements 41, 42, the actuation area 33 and the opening 34 forms the edge 32, and all of the listed components are formed in one piece.

[0068] 7C-7E correspond to the method steps described in relation to 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. Thereby, the contact element 53 is at least partially mechanically separated from the active area 33.

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

[0070] In Figures 8A-8C, first control regions 521 and 521' are labeled and the first control region 521 is controlled by a first AC signal having a first frequency and the first control region 521' is controlled 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 vibration relative to the drive ring 20 about a first axis of rotation formed by the first torsion spring element 41. In Figures 8D and 8E the second control areas 522 and 522' are correspondingly labelled, the second control area 522 being controlled by a second alternating signal having a second frequency and the second control area 522' by a second alternating signal having the second frequency but phase shifted by 180°, respectively, 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 in combination with the control scheme of Figure 8E, respectively, so that the control area 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 relation to FIGS. 4A-5E, in which, in addition to the preferred parameters adopted above in relation to 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 hysteretic behavior.

[0072] 9A-9E relate to the control shown in FIG. 8A for generating a first torsional vibration. For this, a resonant frequency of 24.39 kHz and a FoV of about 42° are obtained, which corresponds to a mechanical half-scan angle of about 10.7°. The twist of the mirror area during vibration is ±23.8 nm, and the mechanical stress is sufficiently small.

[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] 11A-11E relate to the control shown in FIG. 8D for generating a second torsional vibration. For this, a resonant frequency of 4.88 kHz and a FoV of about 75° are obtained, which corresponds to a mechanical half-scan angle of about 18.7°. The twist of the mirror area during vibration is ±7.6 nm, and the mechanical stress is sufficiently small.

[0075] 12A-12E relate to the control shown in FIG. 8E for generating a second torsional vibration. For this, a resonant frequency of 4.88 kHz and a FoV of about 45° are again obtained, which corresponds to a mechanical half-scan angle of about 11.4°. The twist of the mirror area during vibration is ±4.5 nm, and the mechanical stress is sufficiently small.

[0076] In Figures 13A and 13B schematic diagrams of a piezoelectric mirror component 100 according to a further embodiment are shown, which form a variant of the mirror component 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 component 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 the mirror element 100 shown in Figures 13A-14E has a smaller active area 33 having a rather rectangular shape. The opening 31 is formed in this embodiment as a rectangle, preferably as a square.

[0078] In Fig. 15, a schematic diagram of an exemplary control scheme via second control areas 522, 522' for the method of operating the piezoelectric mirror component 100 according to Figs. 13A-14E is shown, where the second control area 522 is controlled by a second AC signal having a second frequency and the second control area 522' is controlled by a second AC signal having the second frequency but shifted in phase by 180°, respectively, in order to transition the drive ring 20 together with the mirror element 10 into a second torsional vibration 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 vibration, for example, the control scheme shown in Fig. 8A can be used.

[0079] 16A-16E show a simulation study similar to that described in connection with Figs. 4A-5E, related to the control shown in Fig. 15. The simulation study showed a pure torsional vibration mode without hysteresis behavior for the second torsional vibration investigated. It shows a resonant frequency of 5.51 kHz and a FoV of 67°, which corresponds to a mechanical half-scan angle of about 17.8°. The twisting of the mirror area during vibration is ±7.6 nm, so the mechanical stress is sufficiently small.

[0080] The above-mentioned piezoelectric mirror components according to some preferred embodiments comprise thin-film piezoelectric elements by means of which the mirror elements are driven in resonance in a first direction and in a second direction, respectively. The result is a so-called Lissajous scan. This allows a higher image resolution at the same resonance frequency for the fast deflection axis, i.e. for the first rotation axis in the above-mentioned embodiment, compared to a raster scan. The following parameters resulting from the required image resolution and repetition frequency can be targeted depending on the application: - Mirror element diameter - 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, which 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 signals 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, in order 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 in turn allows the thickness to be reduced somewhat. The thickness is derived from the desired mirror element diameter, the suspension, the desired frequency and the 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 in addition, due to the moment of inertia of the drive ring, the frequency is reduced.

[0082] Furthermore, the piezoelectric mirror components described herein may have one or more of the following advantages: - Both vibrations are realized by torsion spring elements, i.e. even for high deflections the vibrations are harmonic, which avoids the anharmonicity caused by bending of the suspension in many other designs, such as for example the so-called "quad pod" designs. - The second torsion spring element for the slower oscillation is arranged on the outside of the drive ring, which moves with it. This makes it possible to optimize the drive for the first torsional oscillation without substantially affecting the characteristics of the second torsional oscillation. - 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 tuning the frequency and deflection angle of the two orthogonal torsional vibrations separately. For example, the ellipticity of the drive ring can be optimized for best control of the first torsional vibration.

[0083] In a particularly preferred embodiment, the mirror element has 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 - Metal of the first electrode: 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 175μm, length 1mm - 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 preferably 1024 x 768 pixels with a full-screen refresh rate of approximately 50 Hz can be achieved: - Material: Silicone - Metal of the first electrode: 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 apparatus 1000 comprising a piezoelectric mirror component 100 according to the previous description. Furthermore, the projection apparatus comprises a laser light source 200 which emits laser light 201 during operation.

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

[0087] The piezoelectric mirror assembly 100 can be controlled via mirror assembly control electronics 203, for example to generate a desired Lissajous figure that can scan a desired image area. Furthermore, sensor electronics 204 can be provided to detect the position and / or frequency of the mirror elements of the mirror assembly 100, preferably in real time. Furthermore, there can be image processing electronics 205, which for example controls the overall image display. This can correspond to the conversion of image or film information into control signals for the laser source 200 and the mirror assembly 100, including in particular the time synchronization between the mirror element positions 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 may be measured in the first AC signal and the first frequency in the second AC signal during operation of the piezoelectric mirror component 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, it is also possible to provide a third control area 523 in addition to the first and second control areas, in which a piezoelectric signal can be measured via the piezoelectric effect. The third control area 523, which may also be called a sensor element or sensor area, may be provided in a suitable position, in particular, so that a good signal can be achieved.

[0091] For example, the third control area 523 may be arranged 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 area being arranged "near the torsion spring element" may in particular mean that the third control area is arranged near or adjacent to the origin of the torsion spring element, and that the first and second control areas are not arranged closer to the torsion spring element than the third control area. In Fig. 18B, purely by way of example, four third control areas 523 are provided, which 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 Fig. 18C. Thereby, it can be achieved that the drive ring 20 is fully available for the control areas 521, 521', 522, 522' during operation. Furthermore, the third control area 523 on the frame element 30 is easier to manufacture and easier to contact, since additional conductive paths 54 for these contacts do not have to be led 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 the 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 the 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 under 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., for example, the same thickness as the drive ring 20, in the hatched area 35 where the third control elements 523 are arranged, while the remaining part 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 disposed 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] Due to the above-mentioned arrangement of the sensor elements Sa, Sb, Sc and Sd on the frame element 30, the deflection in two directions can be detected simultaneously, i.e. the deflection around the first torsion element 41 and the deflection around 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 the sake of brevity the signals of the sensor elements are also called Sa, Sb, Sc and Sd, the vibrations around the first torsion spring element 41 can be ascertained 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 deflections around the second torsion spring element 42 can be ascertained 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. By using more than one of the mentioned linear combinations, the measurement accuracy can be increased. Alternatively, it is also possible for example for only two third control regions 523 to be present, since these are in principle sufficient to obtain the desired information. For example, there may only be 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, in case of only two sensor elements, the two sensor elements should not be arranged diagonally to each other, but on the same side with respect to the first torsion spring element 41 or the second torsion spring element 42.

[0096] It is further possible that there are first and / or second control areas which are used alternately in a time-division multiplexed manner to drive the mirror elements or the drive ring and to measure the piezoelectric signal. For this, as shown in FIG. 18C, for example, there can be at least several first or second control areas 521, 521', 522, 522', which are simultaneously provided as a third control area. This can mean, in particular, that the driving and the position determination are performed at different times. This can be achieved, for example, by a suitable pulse width modulation, so that alternately, the mirror elements are driven for a certain number of periods and measurements are performed for a smaller number of periods. Due to the high mechanical quality, only little deflection of the mirror elements is then lost.

[0097] Furthermore, for position and / or frequency measurements, there may be at least two electrode elements 61, 61', 62, 62', 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 track sections. A first electrode element 61 may be arranged, for example, on the frame element 30, and a 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 also 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 which moves between the electrode elements 61', 62' during the movement. Correspondingly, two electrode elements can also be arranged on the drive ring 20 on either side of the mirror element 10.

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

[0100] In connection with the above figures, a circular mirror area 11 is shown throughout. Alternatively, the mirror area 11, and therefore also the reflective coating 15, can be elliptical, as shown in the cross-sectional views of the mirror part in Figures 19A and 19B, with a larger elliptical axis G and a smaller elliptical axis K. Preferably, the larger elliptical axis G is oriented along a first direction and the smaller elliptical axis K is oriented along a second direction, as shown in Figure 19A. Alternatively, the larger elliptical axis G can be oriented along a second direction and the smaller elliptical axis K can be oriented along a first direction, as shown in Figure 19B. The opening 13 has the shape of an elliptical arc in the case of an elliptical mirror area 11. The ratio of the larger elliptical axis G to the smaller elliptical 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 relation to 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 relation to the drawings can alternatively or additionally have further features according to the description in general part.

[0102] The invention is not limited thereto by the description based on the examples, but rather includes all novel features and all combinations of features, including in particular 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 area 522,522' Second control area 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 Devices 205 Image processing electronic equipment 206 Laser Control Electronic Equipment 1000 projection equipment G,K Ellipse axis Sa, Sb, Sc, Sd sensor element

Claims

1. 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 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 greater than the second diameter.

2. The piezoelectric mirror assembly of claim 1 , wherein the drive ring has an elliptical shape.

3. 3. A piezoelectric mirror assembly as described in claim 1 or 2, 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.

4. 4. A piezoelectric mirror component according to claim 1, wherein 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 straight line, and 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 straight line.

5. - 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; - said edge region is connected to said mirror region via two connection regions; The piezoelectric mirror component according to any one of claims 1 to 4.

6. 6. The piezoelectric mirror assembly of claim 5, wherein a reflective coating is applied over said mirror area, and said edge areas and said connection areas are free of said reflective coating.

7. 7. The piezoelectric mirror component according to claim 5, wherein the mirror region is formed in a circular or elliptical shape.

8. A piezoelectric mirror component as described in any one of claims 1 to 7, wherein the frame element surrounds the drive ring and has an opening penetrating the frame element, and the drive ring and the at least one second torsion spring element are arranged within the opening.

9. A piezoelectric mirror component according to any one of claims 1 to 8, wherein the mirror element and the drive ring have a thickness smaller than at least one edge of the frame element, and the frame element, the drive ring, the mirror element and the torsion spring element are integrally formed.

10. A piezoelectric mirror component according to any one of claims 1 to 9, wherein a first electrode and a second electrode structured into a plurality of control regions are applied onto the drive ring, and a piezoelectric layer is arranged between the first electrode and the second electrode.

11. 11. The piezoelectric mirror component according to claim 10, wherein the first electrode and the piezoelectric layer are applied at least partially onto the frame element.

12. 12. A piezoelectric mirror assembly as claimed in claim 11, wherein the second electrode is applied in an active area of ​​the frame element surrounded by an edge, the active area having a smaller thickness than the edge.

13. 13. The piezoelectric mirror assembly of claim 12, wherein the active area is partially separated from the edge by at least one opening.

14. - 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 any one of claims 10 to 13.

15. A piezoelectric mirror assembly according to any one of the preceding claims, 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.

16. A piezoelectric mirror component according to any one of claims 1 to 14, 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.

17. 17. The piezoelectric mirror component of claim 16, 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.

18. A method for operating a piezoelectric mirror component as claimed in any one of claims 1 to 17, wherein the mirror element (10) is transitioned to a first torsional vibration by a first electrical alternating 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 alternating signal having a second frequency and acting on a second control area (522, 522').

19. 20. The method of claim 18, wherein the second frequency is measured in the first alternating signal and the first frequency is measured in the second alternating signal during operation of the piezoelectric mirror component.

20. 20. The method of claim 18, wherein there is a third control region (523), and the piezoelectric signal is measured in the third control region.

21. 19. The method of claim 18 when dependent on claim 13, wherein the capacitance of the capacitor is measured.

22. 20. The method of claim 18, wherein there are first and / or second control regions, the first and / or second control regions being used alternately in a time division multiplexed manner to drive the mirror elements or the drive ring and to measure piezoelectric signals.

23. A laser light source (200); A piezoelectric mirror component (100) according to any one of claims 1 to 17, A projection device (1000) comprising:

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