Device comprising a vibratably suspended optical element

The underlying invention presents a device which connects a vibratably suspended optical element to at least two actuators mounted fixedly on one side via curved spring elements, wherein the actuators are implemented to cause the vibratably suspended optical element to vibrate via the curved spring elements. Both the actuators and the entire system may be implemented to be more robust and be operated more reliably due to the curved shaping of the spring elements.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from German Patent Application No. 10 2013 209 234.2, which was filed on May 17, 2013, and is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

When operating micromirrors, including piezoelectric micromirrors operated in resonance, a frequent objective is to implement both a high resonant frequency and a large deflection of the micromirror. However, it is difficult to achieve a high resonant frequency in combination with a large deflection of the micromirror at the same time. U.S. Pat. No. 7,190,502 B2 describes a device using which a deflection of 12.4 mm can be achieved at a resonant frequency of 10.6 kHz. U.S. Pat. No. 8,125,699 B2 shows devices using which an amplitude of 5.25 mm can be achieved at a resonance frequency of 15.6 kHz and 9 mm at a resonant frequency of 304 Hz. Devices of U.S. Pat. No. 6,657,764 B1 can be operated at amplitudes of 40 mm at a resonant frequency of 500 Hz and an amplitude of 3.9 mm at a resonant frequency of 17.2 kHz.

In order to simultaneously achieve large deflections and high resonant frequencies, EP 2233 961 A1 discloses a setup in which a vibratable, oscillating system comprises laterally arranged actuators and a micromirror arranged in the center which, connected to one another via a torsion spring, form a vibratable overall system and exhibit a common resonant frequency. In order to allow a high operating frequency, the actuators are driven in the “one-node mode”, which is the frequency of the second eigenmode of a bending beam. This requires a small layer thickness of the actuators, which makes mechanical stability of the structure sensitive towards mechanical damage and constant load. At the same time, the overall system exhibits a parasitic and, in operation, undesired mode which is very close to the “one-node mode”, making operation of the device presented in EP 2233 961 A1 difficult.

U.S. Pat. No. 6,198,565 B1 presents one way of implementing micromirrors operated in resonance, using which large deflections, high resonant frequencies and operating modes which are clearly separated from other modes can be achieved. However, it is of disadvantage with this solution that the springs connecting the micromirror to the actuators are provided with high mechanical loads, with the result that high levels of material stress are already reached with moderate mirror deflections, causing the material of the springs to fail, so that the springs will break.

FIGS. 13aand 13bshow pictures of such a micromirror the spring elements of which contain defects.

U. Baran et al., in their publication “High Frequency Torsional MEMS Scanner for Displays”, have achieved an optical scanning angle of the micromirror of 38.5° at a resonant frequency of 39.5 kHz using a design presented inFIG. 14.

In this design, a cascading oscillator system is constructed from several vibration frames. The vibration frames here are formed of piezoelectric actuators which, in turn, are connected to the micromirror arranged in the center and an outer frame each via broad torsion springs. This avoids material overload and at the same allows a large scanning angle and, thus, a high amplitude and a high resonant frequency. Of disadvantage with this solution are, on the one hand, increased space requirements for the setup, since the dimensions of the individual components, due to the existence of a double frame and the large width of the springs, are correspondingly large and a relatively low energy efficiency of the setup, since both ends of the piezoelectric actuators are each mounted to be movable so that the force generated by the actuators cannot be transferred completely to the micromirror or the torsion springs.

Consequently, a concept for suspending a micromirror which allows both high amplitudes and scanning angles and high resonant frequencies would be desirable.

Thus, the object of the present invention is providing a device comprising a vibratably suspended optical element such that high material stress can be avoided and a higher resonant frequency of the optical element is allowed, while at the same time allowing energy-efficient operation of the device by an optimum flux of force.

SUMMARY

According to an embodiment, a device may have: an optical element suspended to be vibratable via curved spring elements; and at least two actuators, each mounted fixedly on one side, which are connected to the vibratably suspended optical element via the curved spring elements to cause the vibratably suspended optical element to vibrate.

According to another embodiment, a device may have: an optical element which is suspended to be vibratable via curved spring elements, wherein the curved spring elements are implemented such that a local orientation of each spring element along a longitudinal center line of the respective curved spring element fulfils the following characteristics: a histogram of the local orientation has a span of ≧60°; the histogram is not located in a contiguous or non-contiguous interval of a length of 6° to more than 90%.

The central idea of the present invention is realizing that the above object can be achieved by connecting actuators which are each mounted fixedly on one side to the vibratably suspended micromirror via curved spring elements. The curved spring elements allow forces to be absorbed such that material failure is prevented despite high operating frequencies and deflection amplitudes.

In accordance with one embodiment, a vibratably suspended micromirror is suspended at two actuators via four torsion springs, the torsion springs being multiply curved and arranged at a distance to a torsion axis of the micromirror so as to allow large deflections of the micromirror by making use of the lever law.

In accordance with alternative embodiments, four torsion springs which connect the vibratably suspended micromirror to actuators all include only one radius of curvature, so that a larger axial extension of the actuators is combined with an efficient utilization of space by the spring elements.

Further embodiments exhibit an arrangement of more than two actuators for causing the vibratably suspended micromirror to vibrate in order to allow tilting of the micromirror around an additional axis to the torsion axis.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1shows a curved torsion spring14which includes a longitudinal center line32along the longitudinal extension of the spring. Starting at a first end of the longitudinal center line32, it includes a curvature section29comprising a curvature of a radius of curvature rK1around a curvature center34at an aperture angle31. The aperture angle31exemplarily is roughly 90°. In the further course of the longitudinal center line, it includes a curvature section27comprising a curvature of a radius of curvature rK2around a curvature center35at an aperture angle37of, exemplarily, 180°. Starting at the section27, there is a region39, in the direction of the second end of the longitudinal center line32, in which the torsion spring14is formed to be straight and which consequently does not include any curvature, i.e. has a zero value curvature or an infinite radius of curvature.

In the sections27and29, starting from the initial orientation, all the local orientations are arranged in an evenly distributed manner in an interval with a span of 90° and 180°, since all the orientations occur evenly since the sections of curvature are shaped to be arcs of a circle, whereas the local orientation in the region39is constant, due to the lack of curvature.

The even distributions of sections27and29result in an even height of a base region of a histogram of the torsion spring14, whereas the sections where the torsion spring has no curvature and thus includes a constant local orientation result in an additional amplitude of the histogram for the orientations of these sections.

The radii of curvature rK1a-d and rK2a-d may be in any relation to one another, wherein the centers34and35of the radii of curvature are arranged alternatingly on one side each along the course of the curved torsion spring14. A center of curvature arranged on one alternating side relative to an adjacent center of curvature corresponds to an alternating change in sign of the radius of curvature along the course of the longitudinal center line.

Although inFIG. 1two radii of curvature, each having a center, are arranged on alternating sides along the longitudinal center line, only a single radius of curvature or any larger number of radii of curvature may be arranged along the longitudinal center line, wherein embodiments describe torsion springs comprising less than ten changes in sign of the radii of curvature.

In combination with the curvature centers34and35and the radii of curvature rK1and rK2, the aperture angles31and37describe aperture angles of sectors of a circle along which the curvatures proceed, the aperture angles each being smaller than or equaling 180°.

Although, inFIG. 1, the radius of curvature changes discontinuously along the length of the torsion spring, a continuous change is of course also possible, which will be discussed in connection withFIG. 9.

Due to the alternating positioning of the curvature center relative to the side of the longitudinal center line32, in the case of a single curvature center, the curved torsion spring14has the course of an arc of a circle and, in the case of several curvature centers, an S-shaped course.

FIG. 2shows a histogram of the local orientation of a curved torsion spring14ofFIG. 1, starting from section39in an orientation of −90°, which in the histogram is represented by the area39′. In the section39, the local orientation is constant over the longitudinal extension, so that the length of section39is arranged proportionately in the histogram in an orientation of −90°. The following curvature to the right of the torsion spring towards an orientation of +90° results in a hatched base region29′ in the histogram, which corresponds to the equidistribution of the local orientations along section27of the torsion spring14. The curvature to the left along section29which follows in the further spring course in section29, from the orientation of +90° to 0°, results in an unhatched area29′ between 0° and +90° in the histogram.

In accordance with the minimum of −90° and the maximum of +90° of the local orientations of the torsion spring, the span of the histogram is an interval of 180°. The interval here is formed continuously since every local orientation between −90° and +90° is formed in the course of the curved torsion spring14, wherein, as is represented by the hatched base region27′ of the histogram, a portion of at least 10 percent of the histogram is distributed evenly between the minimum local orientation of −90° and a maximum local orientation of +90°.

Alternative embodiments comprise curved torsion springs of only one or several radii of curvature, so that the span of the histograms is greater than 60° and smaller than 360°.

FIG. 3shows a device10comprising a vibratably suspended micromirror12which is suspended on center at two actuators16aand16bvia four curved torsion springs14a-d. The actuators16aand16bare each cantilevered fixedly on one side and arranged such that a deflectable end of the actuator faces the micromirror12. The actuators16aand16bare implemented to be piezo-actuators and each include a substrate and a piezoelectric functional layer arranged thereon so that the actuators16aand16bare implemented as bending beams. Driving an actuator16aor16bresults in a deflection of the deflectable end arranged opposite the fixedly cantilevered side in the direction out of the plane of the drawing, as will be illustrated below graphically.

When the actuators16aand16bare operated in opposite phases so that one of the actuators16aor16bmoves in a direction facing the viewer and the other one of the actuators moves in a direction facing away from the viewer, the micromirror12tilts around a torsion axis18. However, when the actuators are operated in phase, the micromirror12moves out of the plane of the torsion axis18. The actuators16aand16b, the micromirror12, and the curved torsion springs14a-dform a spring-and-mass system of a common resonant frequency. The actuators16aand16bare arranged to be symmetrical around the torsion axis18, wherein an also symmetrical tilting of the micromirror12around the torsion axis18is achieved. The curved torsion springs14a-dare connected to the actuators16aand16bat actuator mounting places22a-d. The ends of the curved torsion springs14a-dfacing away from the actuators16aand16bare connected to the micromirror12at mirror mounting places24a-d. Thus, both the actuator mounting places22a-dand the mirror mounting places24a-dare implemented such that the transitions from the curved torsion springs14a-dto the actuators16a-band from the curved torsion springs14a-dto the micromirror12are implemented to be rounded, wherein outer edges of the respective curved spring element14a-dare guided to the actuator16aor16band the micromirror12tangentially, wherein an angular or discontinuous transition between the elements is avoided.

The curved course of the torsion springs14a-dallows an implementation of the springs which is provided with a larger longitudinal extension compared to spring elements of a straight course so that forces induced by a deformation of the material of the springs are distributed in a larger material region. In contrast to torsion springs redirected in an angular and, thus, discontinuous manner, a continuous transition of the different radii of curvature results in force peaks at places of discontinuity to be avoided.

A rounded transition between the actuator/spring or spring/micromirror elements reduces force peaks occurring in the material with a deformation and avoids excessive material fatigue at these places. The result is an additionally increased operating time of the device.

In order to reduce rotational or tilting movements around an axis other than the torsion axis18, the actuator mounting places22a-dare arranged relative to one another such that the actuator mounting places22aand22band the actuator mounting places22cand22dare each arranged in pairs on a line26aand26b, respectively, the lines26aand26bbeing parallel to the torsion axis18. In combination with a symmetrical arrangement of the mirror mounting places24a-d, the result is minimization of movements of the micromirror12which are not around the torsion axis18.

The actuators16aand16bmay be configured such that a longitudinal extension x1of the actuators16aand16bis greater than a radius of the round micromirror12. Increasing the extension x1allows a larger deflection of the deflectable end of the actuators and thus of the actuator mounting places22a-d. Said larger deflection produces a larger material deformation which is made possible by the shape of the curved torsion springs14a-d. Thus, the longitudinal dimension x1represents a distance from the fixed cantilevered part of an actuator16aor16balong an axis arranged perpendicular to the torsion axis18to an actuator mounting place22a-b, i.e. a dimension along an extension in which the actuators bend as a bending beam in accordance with the implementation.

The mirror mounting places24a-dare arranged at a distance x3from the torsion axis18. The distance x3generates a leverage such that a deflection of the actuators16aand16b, induced by the actuators16aand16band transmitted by the curved torsion springs14a-dis transferred onto the micromirror12to an extent depending on the distance x3.

The micromirror12inFIG. 1is formed to be of a round shape and of a constant radius r. In embodiments, an alternative micromirror includes a different shape, exemplarily that of an ellipse. In this case, the distance x1may be selected to be larger than half of the longest distance between any two points of a main side of the micromirror12. When, as is shown inFIG. 1, the micromirror12is formed to be a round element, half of the longest extension between any two points corresponds to the radius r.

The distance x3defining the leverage allows a larger deflection of the micromirror12relative to an arrangement of torsion springs in the torsion axis with equal forces of the actuators16aand16b, or an identical deflection of the micromirror12with a smaller actuator deflection.

Further embodiments exhibit an arrangement of several actuators, wherein the actuators are arranged to be symmetrical around the torsion axis and/or an axis of symmetry perpendicular to the torsion axis and only a single curved torsion spring is arranged at each actuator. The distance x2is then determined as the distance between two actuator mounting places in a half-plane defined by the torsion axis or the axis of symmetry.

FIG. 4ashows a side view of the device10in an undeflected state. The actuators16aand16b, in analogy toFIG. 3, are each formed as piezo actuators including a substrate28aand28band a piezoelectric functional layer. The actuators16aand16binclude a thickness H1which is in a defined relation to a thickness H2of the micromirror12, the ratio between H1and H2roughly corresponding to 1:1. Alternative embodiments include a ratio between H1and H2between 0.1 and 2.

The substrates28aand28bof the actuators16aand16b, the curved torsion springs14aand14band the micromirror12may, as is exemplarily illustrated inFIGS. 4aand 4b, be formed from the same material and integrally, wherein the integral characteristic may exemplarily be achieved from a common starting medium by means of a time-controlled etching process or an etch stop layer. In addition, the substrate33where the actuators16aand16bare suspended, is also formed integrally with the substrate28aand28bof the actuators16aand16band, thus, the curved torsion springs14aand14b, and the micromirror12, so that exemplarily the time-controlled etching process removes volume parts of a portion of a wafer at laterally and axially differing locations, wherein the structures of the substrate28aand28bof the actuators16aand16b, that of the curved torsion springs14aand14band of the micromirror12are formed, as is the substrate33, from the wafer portion.

FIG. 4bshows the device10in a deflected state in which the actuator16ais deflected in one direction and the actuator16bin the opposite direction. The deflection of the actuators16aand16bresults in a deformation of the curved torsion springs14aand14band in tilting of the micromirror12around the torsion axis18.

FIG. 5shows part ofFIG. 1with a top view of the mounting places22aand24awhich connect the torsion spring14ato the micromirror12and the actuator16atangentially, and the course of the curved torsion spring14a. Along its continuous course, a longitudinal center line32aof the curved torsion spring14acomprises the straight section39aand the two curvature sections27aand29aeach including a constant radius of curvature rK1a and rK2a and a curvature center34aand35a, respectively. The local radii of curvature rK1a and rK2a may be implemented such that they are each larger than half of the mean width of the curved torsion spring and at the same time, in each curvature section27aand29a, the mean value of the magnitude of the respective radius of curvature rK1a or rK2a is smaller than 10 times the overall length of the longitudinal center line32a.

In accordance with alternative embodiments, a vibratably suspended optical element, exemplarily a micromirror, may also be arranged on a substrate via curved spring elements with no actuator, in particular when energy for causing the vibratably suspended optical element to vibrate is introduced into the vibratable system alternatively, exemplarily via a fluid stream flowing around the vibratably suspended optical element.

FIG. 6shows a top view of a device20in which the device10has been extended in that two additional torsion springs36aand36bof a straight shape are arranged at the micromirror12, of which the end facing away from the micromirror12is arranged at an immobile anchor point and the longitudinal course of which is identical to the torsion axis18. The straight torsion springs36aand36bhere have no direct connection to the curved torsion springs14a-d. The straight torsion springs36aand36bare configured to stabilize tilting of the micromirror12.

Although the arrangement of two straight torsion springs36aand36bhas been described forFIG. 6, alternative embodiments include a different number of straight torsion springs which are arranged symmetrically around and parallel to the torsion axis18.

FIG. 7shows a top view of a device30in which the micromirror12is arranged at the actuators16aand16bvia four curved torsion springs14a-d. Thus, the curved torsion springs14a-dare shaped such that two curved torsion springs14aand14cand14band14deach arranged on a side of an axis of symmetry41which is arranged to be perpendicular to the torsion axis18include a common section38aand38bof the torsion spring. Starting at the respective actuator mounting places, the curved torsion springs14a-dfollow a curved course to the torsion axis18, wherein the curved torsion spring14ais merged with the curved torsion spring14cand the curved torsion spring14bis merged with the curved torsion spring14dat the torsion axis18, forming the further straight part38aof the curved torsion springs14aand14cand the further straight part38bof the curved torsion springs14band14d, respectively. The distance x3of the device10inFIG. 1is implemented with a zero extension.

Merging the curved spring elements as shown in the above embodiment allows compensating manufacturing tolerances when manufacturing the device such that, instead of four mirror mounting places, only two mirror mounting places are formed, for which consequently only one orientation relative to the torsion axis of the micromirror is necessitated, thus increasing the precision of the tilting motion of the micromirror12.

FIG. 8shows a second embodiment of a torsion spring. It shows a device40which includes singly curved torsion springs42a-dwhich connect the micromirror12to the actuators16aand16bsuch that an excitation induced by the actuators16aand16btilts the micromirror12around the torsion axis18or moves same along a plane which includes the torsion axis18. The singly curved torsion springs42a-dare connected to the micromirror12at mirror mounting places44a-d. Thus, the mirror mounting places44a-dare, in analogy to the mirror mounting places of preceding embodiments, configured to be rounded, so that peaks of material stress occurring at structural transitions between the singly curved torsion springs42a-dand the micromirror12are minimized.

A lateral distance x2between the actuator mounting places46aand46band between46cand46dexemplarily is more than 150% of the largest distance between any two points of a main side of the micromirror12. A larger extension x2results in a greater deflecting force and, thus, a faster deflection of the micromirror12.

In analogy to the actuator mounting places22of the curved torsion springs14, the actuator mounting places46a-dof the singly curved torsion springs42a-dare also implemented to be rounded or guided to the actuators16aand16btangentially. Along a continuous longitudinal center line of the singly curved torsion springs42a-d, all the radii of curvature of the singly curved torsion springs42a-dare on the same side of the longitudinal center line, wherein a mean value of each radius of curvature is smaller than 10 times the length of the longitudinal center line. Thus, the singly curved torsion springs42a-dare implemented such that their course basically corresponds to a quarter of an ellipse.

Alternative embodiments exhibit singly curved torsion springs, the course of which roughly corresponds to an arc of a circle. Thus, along the courses, the singly curved torsion springs includes one or several radii of curvature around one or several curvature centers, wherein all the curvature centers are arranged on the same side of the longitudinal center line of the respective singly curved torsion spring and each local radius of curvature has, over a length of the center line, a larger magnitude than half of a mean width of the respective singly curved torsion spring.

In order to reduce the space necessitated for the entire structure, this arrangement of singly curved torsion springs may be of advantage compared to an arrangement of curved torsion springs of the preceding embodiments. InFIG. 8, the curvature of the singly curved torsion springs42a-dis implemented such that, starting from the actuator mounting places46a-d, the singly curved torsion springs42a-dinclude only sections which, except for the actuator mounting places46a-d, are only directed towards the micromirror12or exhibit a curvature towards the micromirror12. In preceding embodiments, the curved torsion springs14have been implemented such that, starting from actuator mounting places22a-d, sections of the curved torsion springs14a-dface away from the micromirror12and a maximum lateral extension, in the direction of the torsion axis18, is defined by the lateral extension of the curved torsion springs14a-d. The maximum lateral setup space in the direction of the torsion axis18of the device40, in contrast, is defined by the lateral extension of the actuators16aand16b.

FIG. 9shows a histogram of the course of curvature of the singly curved torsion spring42cof the device40ofFIG. 8starting from the actuator16bin the direction of the micromirror12. Starting with the tangential arrangement of the singly curved torsion spring42cat the actuator16bwith the local orientation of 0°, the curvature of the singly curved torsion spring42cdevelops continuously to an orientation of +90°. From a minimal orientation of 0° to a maximum orientation of +90°, the histogram has a span of 90°. At least 10% of the integral area of the histogram, which inFIG. 9is illustrated in a hatched manner, are arranged to be evenly distributed, which means: an equidistribution over the span of an area of 10% of the histogram remains below the histogram over the entire span. At the same time, the histogram ofFIG. 9does not contain a contiguous or non-contiguous interval with a length of 6%, which includes the area of the histogram to more than 90% so that the orientations of a singly curved torsion spring include a measure of equidistribution within the span. The continuous course of the non-hatched region indicates that radii of curvature change continuously along the course of the torsion spring.

Alternative embodiments include singly curved torsion springs the histograms of which comprise spans of larger than or equal to 60° and smaller than or equal to 270°.

FIG. 10shows a schematic top view of a device60including a micromirror12which is arranged at the actuators16aand16bvia four singly curved torsion springs42a-d. Additionally, curved torsion springs14a-dwhich support deflection of the actuators16aand16brelative to the substrate33are arranged at the actuators16aand16b. The curved torsion springs14aand14cand14band14deach comprise, in pairs and in analogy toFIG. 5, the common sections38aand38b, respectively, of the curved torsion springs.

By additionally arranging curved torsion springs between the actuators and the substrate, stabilization of the deflection motion can be achieved, wherein, in principle, any combination of curved and singly curved torsion springs is possible.

In principle, the ends of the curved torsion springs14a-dfacing away from the actuators16aand16bmay also be arranged at further actuators in order for the micromirror12to be arranged to be rotatable along a second axis different from the torsion axis18and movable along an axis perpendicular to the torsion axis18.

FIG. 11schematically shows ways of arranging actuators16a-drelative to the micromirror.

FIG. 11a, in analogy to the preceding embodiment, shows a symmetrical arrangement of the actuators16aand16baround the torsion axis18. The actuators16aand16bhere are cantilevered fixedly at a side facing away from the micromirror12, in a parallel manner and spaced apart from the torsion axis18, and are arranged to be symmetrical to the axis of symmetry41.

FIG. 11bshows an arrangement of four actuators16a-dwhich are arranged to be both symmetrical to the torsion axis18and symmetrical to the axis of symmetry41, so that one actuator16a-deach is arranged in a quadrant of a coordinate system spanned by the torsion axis18and the axis of symmetry41.

FIG. 11cshows an arrangement of actuators in analogy toFIG. 11b, wherein an arrangement of further actuators is indicated by points between the actuators16aand16band between the actuators16cand16d. Further actuators are arranged to be symmetrical to the axis of symmetry41. When, for example, an additional fifth and sixth actuator are arranged,FIG. 11bis extended in that the additional fifth and sixth actuator are arranged in the course of the axis of symmetry41.

FIG. 11dshows an arrangement of actuators16a-din analogy toFIG. 11b, wherein the actuators are cantilevered fixedly in a course in parallel to the axis of symmetry41and the freely deflectable ends of the actuators16a-dare facing the axis of symmetry41and are in parallel to the axis of symmetry41.

FIG. 11eshows an arrangement of actuators16a-din analogy toFIG. 11d, wherein the fixed cantilevered part of the actuators16a-dis arranged to be facing the axis of symmetry41and the freely deflectable end of the actuators16a-dto be facing away from the axis of symmetry41.

In principle, any number of actuators may be arranged, wherein the actuators are arranged to be both symmetrical to the torsion axis18and symmetrical to the axis of symmetry41, which is perpendicular to the torsion axis18, and the axes of symmetry cross in the center of the micromirror12.

The embodiments described provide an oscillating system which includes a micromirror and external piezoelectric actuators. In contrast to known solutions, the actuators may be implemented such that they exhibit higher resonant frequencies than the micromirror, so that a greater layer thickness of the actuators may be used and the entire structure is implemented to be more robust due to the large layer thickness.

Furthermore, the actuators may be operated in the zero-node mode, the first eigenmode of a bending beam. In contrast to the one-node mode, in the zero-node mode, neighboring parasitic modes in the frequency range are at relatively large distances to one another, so that the eigenmode is predominant and the influence of parasitic modes, which limits operation of the micromirror, is reduced.

Furthermore, discontinuous material courses of torsion springs, like, for example, in the torsion springs shown inFIG. 13, formed at a 90° angle are avoided by the curved and singly curved torsion springs comprising a continuous course, and thus force peaks and mechanically overstressed locations along the course of the curved and singly curved torsion springs are prevented. Rounded or tangentially implemented mounting places of the springs at the micromirror and/or actuators additionally prevent mechanically overstressed locations from occurring at the ends of the torsion springs.

All in all, the micromirror system described comprises a high resonant frequency and is of a stable and robust design. When the torsion springs are arranged on the micromirror at a distance from the torsion axis, the lever arm may be made use of in that the distance from the torsion axis to the mirror mounting places acts as a lever arm and the force of the actuators is transferred efficiently, thereby achieving a large deflection of the micromirror. Using the torsion springs as a lever at the same time prevents locations with too high a mechanical stress due to the design of the torsion springs and the mounting places at the actuators and the micromirror.

Although the preceding embodiments have shown torsion springs connecting a micromirror to actuators, in principle different elements may also be arranged at the ends of the torsion springs facing away from the actuators, such as, for example, lenses or parts of electronic switches.