Method and apparatus for operating a micro-mirror

Abstract

The present disclosure relates to a method and apparatus for operating a micro-mirror device (10) comprising a mirror (300) configured to be driven to oscillate about at least one axis. This involves selecting an operating mode among at least two operating modes of the micro-mirror device (10), wherein a first operating mode is associated with oscillation of the mirror (300) substantially at a resonance frequency of an Nth transverse eigenmode of oscillation of the mirror (300) with respect to the axis (A1), and a second operating mode of the at least two operating modes is associated with oscillation of the mirror (300) substantially at a resonance frequency of another Mth transverse eigenmode of oscillation of the mirror (300) with respect to the axis (A1).

Description

Technical Field

[0001] This disclosure relates to a method and apparatus for operating a micromirror, and more particularly to a micromirror device for 1D scanning and / or 2D scanning, 2D projection and / or interferometry applications. Specifically, this disclosure relates to a method and apparatus for operating 1D or 2D micromirrors, such as 1D or 2D-MEMS micromirrors. Background Technology

[0002] In the prior art, micromirror devices for various applications are described, such as micromirror devices based on MEMS (microelectromechanical systems) technology, including 1D and / or 2D scanning applications, 2D projection applications and / or interferometry applications.

[0003] For example, in the non-patent literature article published on November 18, 2020, by authors K. Meinel et al. 2D Scanning Micromirror with Large Scan Angle and Monolithically Integrated Angle Sensors Based on Piezoelectric Thin Film Aluminum Nitride "Sensors 2020, Vol. 20, 6599 describes a resonantally operated, piezoelectrically driven 2D micromirror device for use in LiDAR scanners or laser scanner projectors. Here, the MEMS mirror is operable to be driven to oscillate about two axes, i.e., in two dimensions (2D), in order to deflect an incident laser beam onto the oscillating mirror according to a so-called Lissajous pattern. The oscillations on the two axes are driven to operate at corresponding resonant frequencies, thereby achieving large tilt angles with high energy efficiency."

[0004] Other resonant 2D micromirrors can be found, for example, in the non-patent literature article published by Y. Liu et al. on September 18, 2022 in Micromachines 2022, Vol. 13, 1550. AlScN Piezoelectric MEMS Mirrors with Large Field of View for LiDAR ApplicationThe text describes resonant, piezoelectrically driven 2D micromirror devices used in LiDAR scanning applications, and author S. Gu-Stoppel's 2016 doctoral dissertation, "Entwicklung, Herstellung und Charakterisierung piezoelektrischerMikrospiegel" (Development, Manufacture and Characterization of Piezoelectric Micromirrors), in Books on Demand, Northerstedt, ISBN: 9783739239583, which describes relevant background information on the development and fabrication of piezoelectrically driven 1D or 2D micromirror devices for various applications such as laser image projection.

[0005] Document US2020 / 0386985A1 also describes piezoelectrically driven 2D micromirror devices for various applications such as LiDAR scanning.

[0006] In the prior art, 2D micromirrors for scanning or projection applications are known to operate with so-called grating patterns, wherein lasers are deflected according to the grating pattern, see, for example... Figure 1 One axis operates at a fast resonant oscillation, while the other axis operates relatively slowly at a frequency much lower than the corresponding resonant frequency of the other axis; this operation is called quasi-static operation. However, a drawback of this quasi-static operation is that relatively high energy is required to achieve a sufficiently high tilt angle of the mirror around the quasi-static axis, making the device less efficient than desired.

[0007] Given this drawback, such 2D micromirrors can preferably be operated resonantly on two axes, wherein oscillations about each corresponding axis are driven to oscillate substantially at (or at least very close to) the corresponding resonant frequency of the corresponding axis. This typically results in so-called Lissajous scanning or projection patterns; see, for example, […]. Figures 2A to 3B An exemplary Lissajous pattern.

[0008] In some preferred applications, the micromirror MEMS design structure can be configured such that the resonant frequencies of the two axes are substantially similar, thereby producing, for example, Figure 2A and Figure 2B The Lissajous pattern is shown as an example.

[0009] For example, Figure 2A and Figure 2BThe lissajous pattern has been created using the online tool https: / / academo.org / demos / lissajous-curves / , and Figure 2A The ratio of the resonant frequencies in the Lissajous pattern is exemplarily chosen to be 9:10, and Figure 2B The ratio of the resonant frequencies in the Lissajous pattern is exemplarily chosen to be 19:20. In some examples, at the typically higher operating frequencies of the micromirror device, the resonant frequency ratio may be chosen to be substantially 1:1.

[0010] However, for projection applications, it can be recognized that, as... Figure 2A Compared to the Lissajous patterns with substantially similar resonant frequencies on the two axes, as exemplified in 2B, some users (typically around 50%) exhibit a subjective, subconscious user preference for images projected from patterns that resemble gratings.

[0011] For this type of user and their subconscious user preferences, a different product is typically needed, in which the MEMS structure is designed such that the resonant frequency of the first axis is significantly greater than, or at least relatively greater than, the resonant frequency of the second axis, to produce a more "grating-like" Lissajous pattern, such as... Figure 3A Or the Lissajous pattern shown as an example in 3B.

[0012] For example, Figure 3A and Figure 3B The lissajous pattern has been created exemplary using the online tool https: / / academo.org / demos / lissajous-curves / , and Figure 3A The ratio of the resonant frequencies in the Lissajous pattern is exemplarily chosen to be 1:9, and Figure 3B The ratio of the resonant frequencies in the Lissajous pattern is exemplarily chosen to be 1:20.

[0013] Therefore, regarding the operation of micromirror devices for image projection applications, one group of users prefers to use patterns that are closer to or more like gratings (such as...). Figure 1 Or according to Figure 3A and Figure 3B The projected image of a Lissajous pattern (such as a Lissajous pattern) can have a better subjective experience, while another group of users prefer to use a more uniform pattern (such as a Lissajous pattern). Figure 2A and Figure 2B The image projected by the projection pattern (such as the Lissajous pattern) can have a better subjective experience.

[0014] Moreover, for other imaging applications, or for projecting images with different aspect ratios (e.g., 4:3, 16:9, or 21:9, etc.), and / or for projecting images with different image resolutions, users may prefer one type of projection pattern to another, and vice versa.

[0015] However, it is preferable to avoid using grating patterns formed by manipulating one of the axes, as this would result in a significant reduction in energy efficiency. Therefore, it is preferable to provide a miniature mirror capable of operating at corresponding resonant frequencies on both axes.

[0016] However, while efficient MEMS micromirror devices can be provided that operate resonantly on both axes at a selected tuning ratio of the resonant frequencies of the two axes, there is another drawback: the need to provide the market with different micromirror MEMS devices tuned to different resonant frequency ratios so that corresponding products can be provided to different user groups to suit their subjective user preferences.

[0017] More generally, in some exemplary aspects, it may be desirable to provide a single micromirror device, and preferably one that is capable of operating the micromirror device efficiently, thereby providing different efficient operating modes, which may include those suitable for different applications and / or application functions, such as 1D and / or 2D scanning, 2D projection and / or interferometry applications.

[0018] In view of the above, the purpose of this disclosure is to provide a method and apparatus for operating a micromirror, which preferably avoids and / or at least improves the above disadvantages, and / or is able to operate the micromirror device efficiently, preferably enabling the provision of different efficient operating modes, which may include those suitable for different applications and / or application functions. Summary of the Invention

[0019] To achieve the above objectives, a method for operating a micromirror device according to claim 1 is provided. Furthermore, apparatus and corresponding computer program products for operating a micromirror device according to other independent claims are provided, such as firmware including a controller. Dependent claims relate to several exemplary embodiments. According to a first aspect, a method for operating a micromirror device is provided. According to a second aspect, a controller for operating a micromirror device and / or an apparatus including such a controller and a micromirror device is provided. According to a third aspect, a computer program product is provided to cause the controller to perform the method for operating the micromirror device.

[0020] In some exemplary aspects, the micromirror device may include a mirror configured to be driven to oscillate relative to one or more axes, preferably including tilt oscillations about at least one axis, for example, for scanning applications and / or for projection applications, and / or including displacement oscillations, for example, for interferometric applications. In some exemplary aspects, the mirror may be held by a structured device layer of a MEMS structure, wherein the structured device layer may include springs to hold the mirror within the frame of the MEMS structure. In some exemplary aspects, the mirror may be configured to be driven to oscillate in two dimensions relative to two axes (2D), for example, for scanning applications and / or projection applications. The micromirror device may include actuators for driving the oscillation of the mirror relative to one or more axes.

[0021] According to some exemplary aspects, operating a micromirror device may include selecting an operating mode among at least two operating modes of the micromirror device, particularly selecting an operating mode among at least two selectable operating modes of the micromirror device.

[0022] According to some exemplary aspects, the first operating mode of the at least two operating modes may be associated with the oscillation of the mirror of the micromirror device, which is preferably relative to a first axis and / or preferably substantially at the resonant frequency of the Nth transverse eigenmode of the mirror's oscillation associated with the first axis.

[0023] According to some exemplary aspects, the second operating mode of the at least two operating modes may be associated with the oscillation of the mirror of the micromirror device, which is preferably relative to the first axis and / or preferably substantially at the resonant frequency of another Mth transverse eigenmode of the mirror's oscillation associated with the first axis.

[0024] According to some exemplary aspects, the selectable operating modes may include two or more operating modes, wherein each selectable operating mode is preferably associated with the oscillation of the mirror of the micromirror device, which is preferably relative to a first axis and / or preferably substantially at the resonant frequency of a corresponding transverse eigenmode of the mirror's oscillation associated with the first axis.

[0025] According to some exemplary aspects, preferably, M and N are different, wherein the transverse eigenmodes of the oscillations associated with the respective particular axis are numbered by positive integers such that N = 1, 2, 3, 4, 5, 6, ... or higher, and M = 1, 2, 3, 4, 5, 6, ... or higher, preferably N ≠ M.

[0026] According to some exemplary aspects, operating a micromirror device may include driving the mirror to oscillate according to a selected operating mode.

[0027] According to some exemplary aspects, operating the micromirror device may include, when a first operating mode is selected, driving the mirror to oscillate (e.g., oscillate around a second axis) substantially at a resonant frequency associated with a Nth transverse eigenmode of the mirror's oscillation, which is associated with a first axis, depending on the selected first operating mode.

[0028] According to some exemplary aspects, operating the micromirror device may include, when a second operating mode is selected, driving the mirror to oscillate (e.g., oscillate around a second axis) substantially at the resonant frequency associated with the Mth transverse eigenmode of the mirror's oscillation, which is associated with the first axis, depending on the selected second operating mode.

[0029] According to some exemplary aspects, the corresponding lateral eigenmode of the selected operating mode (first and / or second operating mode) may be an even-numbered lateral eigenmode associated with the first axis. Preferably, the oscillation of the mirror can be driven according to the selected operating mode to perform projection and / or scanning operations of the micromirror device, preferably utilizing a light beam reflected by the oscillating mirror.

[0030] According to some exemplary aspects, the corresponding lateral eigenmode of the selected operating mode (first and / or second operating mode) may be an odd-numbered lateral eigenmode associated with the first axis. Preferably, the oscillation of the mirror can be driven according to the selected operating mode to perform interferometric measurement operations of the micromirror device, preferably utilizing a beam of light reflected by the oscillating mirror.

[0031] According to some exemplary aspects, the Nth lateral eigenmode and the Mth lateral eigenmode are different even-numbered lateral eigenmodes of the mirror's oscillation. Therefore, preferably, M and N are different even-numbered positive integers, wherein the lateral eigenmodes of the oscillation are numbered by positive integers such that N = 2, 4, 6, 8, ... or higher, and M = 2, 4, 6, 8, ... or higher, where N ≠ M. This allows switching between different scanning / projection applications using different resonant frequencies.

[0032] According to some examples, N=2 and M=4, 6 or 8 (and vice versa).

[0033] According to some exemplary aspects, the Nth transverse eigenmode and the Mth transverse eigenmode are different odd-numbered transverse eigenmodes of the mirror's oscillation. Therefore, preferably, M and N are different odd-numbered positive integers, wherein the transverse eigenmodes of the oscillation are numbered by positive integers such that N = 1, 3, 5, 7, ... or higher, and M = 1, 3, 5, 7, ... or higher, where N ≠ M. This allows switching between different interferometric applications using different resonant frequencies.

[0034] According to some exemplary aspects, the Nth lateral eigenmode can be an even-numbered lateral eigenmode of the mirror's oscillation, and the Mth lateral eigenmode can be an odd-numbered lateral eigenmode of the mirror's oscillation. This allows switching between projection / scanning applications and interferometric applications.

[0035] According to some exemplary aspects, the operating modes of the micromirror device may also include one or more operating modes, including at least a third operating mode associated with an oscillation of the mirror about at least one axis at a third resonant frequency of another Kth eigenmode of the mirror's oscillation, wherein K is different from each of M and N.

[0036] According to some exemplary aspects, operating the micromirror device may include switching from a first operating mode to a second operating mode, wherein, preferably, selecting an operating mode includes switching from the first operating mode to the second operating mode.

[0037] According to some exemplary aspects, operating the micromirror device may include switching from a second operating mode to a first operating mode, wherein, preferably, selecting an operating mode includes switching from a second operating mode to a first operating mode.

[0038] In other words, according to some exemplary aspects, selecting an operating mode includes switching between a first operating mode and a second operating mode.

[0039] According to some exemplary aspects, the corresponding lateral eigenmodes of the first and second operating modes may be different even-numbered lateral eigenmodes associated with the first axis, and the switching between the first and second operating modes may preferably be switching between two operating modes for performing projection or scanning operations of the resonant operation of the micromirror device at different corresponding resonant frequencies associated with the first axis.

[0040] According to some exemplary aspects, the corresponding lateral eigenmodes of the first and second operating modes may be different odd-numbered lateral eigenmodes associated with the first axis, and the switching between the first and second operating modes may preferably be switching between the two operating modes for interferometric measurement operations of resonant operation of the micromirror device at different corresponding resonant frequencies associated with the first axis.

[0041] According to some exemplary aspects, the corresponding transverse eigenmode of the first operating mode may be an even-numbered transverse eigenmode, and / or the corresponding transverse eigenmode of the second operating mode may be an odd-numbered transverse eigenmode (or vice versa), and the switching between the first operating mode and the second operating mode may preferably be switching between an operating mode for performing the resonant operation of the micromirror device, which is a projection or scanning operation, and an operating mode for performing the resonant operation of the micromirror device, which is an interferometric measurement operation.

[0042] According to some particularly preferred exemplary aspects, the mirror is configured to be driven to oscillate in two dimensions, preferably relative to a first axis and another second axis, for example, oscillating around the first axis and / or around the second axis, for example, preferably oscillating in two dimensions, for example, to preferably enable the generation of two-dimensional projection or scanning patterns, for example, by reflecting infusion onto the oscillating mirror to generate two-dimensional projection or scanning patterns.

[0043] According to some exemplary aspects, operating a micromirror device may include driving the mirror to oscillate according to a selected operating mode, including driving the mirror to oscillate substantially resonantly relative to a first axis and driving the mirror to oscillate substantially resonantly relative to a second axis.

[0044] According to some exemplary aspects, the first operating mode may be associated with the oscillation of the mirror about the second axis, which is substantially at the resonant frequency of the Nth transverse eigenmode of the mirror's oscillation.

[0045] According to some exemplary aspects, the first operating mode may be associated with the tilting oscillation of the mirror about the second axis, preferably driven substantially by the resonant frequency of the even-numbered Nth transverse eigenmode of the mirror's oscillation relative to the first axis.

[0046] According to some exemplary aspects, the second operating mode may be associated with the oscillation of the mirror about a second axis, which is essentially at the resonant frequency of the Mth eigenmode of the mirror's oscillation.

[0047] According to some exemplary aspects, the second operating mode may be associated with the tilting oscillation of the mirror about the second axis, preferably driven substantially by the resonant frequency of the Mth eigenmode of another even-numbered oscillation of the mirror relative to the first axis.

[0048] According to some exemplary aspects, operating the micromirror device may also include driving the mirror to oscillate around a first axis substantially at the resonant frequency of the mirror's oscillation around a first axis, preferably simultaneously driving the mirror to oscillate around a second axis according to a selected operating mode, preferably to generate a two-dimensional projection or scanning pattern, for example, by reflecting a light beam onto the oscillating mirror.

[0049] According to some exemplary aspects, operating the micromirror device may also include generating a Lissajous scan or projection pattern by reflecting a beam of light onto the mirror, preferably simultaneously driving the mirror to oscillate around the first axis substantially at a resonant frequency of the mirror oscillating around the first axis and / or driving the mirror to oscillate around a second axis according to a selected operating mode.

[0050] According to some exemplary aspects, a first type of Lissajous pattern is generated in a first operating mode and / or a second type of Lissajous pattern is generated in a second operating mode.

[0051] According to some exemplary aspects, particularly in the second operating mode, a first ratio according to the first operating mode between the resonant frequency of the oscillation of the mirror about the first axis and the corresponding resonant frequency of the Nth eigenmode of the oscillation of the mirror about the second axis is substantially equal to or greater than 1:1.2 and / or substantially equal to or less than 1:0.8, particularly substantially equal to or greater than 1:1.1 and / or substantially equal to or less than 1:0.9, and preferably, the first ratio is substantially 1:1.

[0052] According to some exemplary aspects, particularly in the second operating mode, the second ratio between the resonant frequency of the oscillation of the mirror about the first axis and the corresponding resonant frequency of the Mth eigenmode of the oscillation of the mirror about the second axis, according to the second operating mode, is substantially equal to or less than 1:2, particularly substantially equal to or less than 1:3, and preferably, the second ratio is substantially equal to or less than 1:5; and / or the second ratio is substantially equal to or greater than 1:20, and preferably, the second ratio is substantially equal to or greater than 1:10.

[0053] According to some exemplary aspects, operating the micromirror device may further include driving the mirror to oscillate around the second axis substantially at the resonant frequency of the Nth eigenmode of the mirror's oscillation around the second axis according to a first operating mode, and / or driving the mirror to oscillate around the second axis substantially at the resonant frequency of the Mth eigenmode of the mirror's oscillation around the second axis according to a second operating mode.

[0054] According to some exemplary aspects, driving the mirror to oscillate around a first axis according to a first operating mode and / or driving the mirror to oscillate around a first axis according to a second operating mode is performed substantially at the same resonant frequency of the transverse eigenmode of the mirror's oscillation around the first axis and / or relative to the second axis.

[0055] According to some exemplary aspects, driving the oscillation of the mirror around the first axis according to the first operating mode and the second operating mode may include operating the oscillation of the mirror around the first axis in different intrinsic modes of the first axis according to the first operating mode and the second operating mode.

[0056] For example, driving the mirror to oscillate around a first axis according to a first operating mode and driving the mirror to oscillate around a first axis according to a second operating mode can be performed substantially at different resonant frequencies of different even-numbered transverse eigenmodes of the mirror's oscillation around the first axis and / or relative to the second axis.

[0057] For example, the oscillation of the mirror about the first axis according to the first operating mode can operate substantially at the resonant frequency of the Jth eigenmode of the oscillation of the mirror about the first axis, and the second oscillation mode can operate substantially at the resonant frequency of the Lth eigenmode of the oscillation of the mirror about the first axis, where J is different from L, and J and L are preferably positive integers with even numbers.

[0058] While certain exemplary aspects have been described above, it should be understood that such exemplary aspects and their features are merely illustrative of this broad disclosure (and should not be construed as limiting), and the exemplary aspects are not limited to the specific constructions and arrangements shown and described above or below, as various other changes, combinations, omissions, modifications, and substitutions are possible in addition to those set forth in the description above or below. Those skilled in the art will understand that various adaptations, modifications, and / or combinations of the aspects just described can be configured or provided. Therefore, it should be understood that other aspects can be practiced in ways different from those specifically described herein. For example, unless expressly stated otherwise, the steps of the process described herein may be performed in a different order than that described herein, and one or more steps may be combined, split, or performed simultaneously. In view of this disclosure, those skilled in the art will also understand that the different aspects described herein can be combined to form other aspects of this disclosure. Attached Figure Description

[0059] Figure 1 This is a schematic illustration of an exemplary raster scan or projection pattern;

[0060] Figure 2A This is a schematic illustration of an exemplary Lissajous scan or projection pattern having similar resonant frequencies on two axes;

[0061] Figure 2B This is a schematic illustration of another exemplary Lissajous scan or projection pattern with similar resonant frequencies on two axes;

[0062] Figure 3A This is a schematic illustration of an exemplary Lissajous scan or projection pattern in which the resonant frequency of one axis is relatively smaller than that of the other axis.

[0063] Figure 3B This is another exemplary illustration of a Lissajous scan or projection pattern where the resonant frequency of one axis is relatively smaller than the resonant frequency of the other axis.

[0064] Figure 4 These are schematic exemplary illustrations of the first to tenth intrinsic modes of oscillation of a two-end clamping beam (also known as a double-end clamping rod vibration or clamp-clamping rod vibration);

[0065] Figure 5 This is a schematic exemplary top view of the device layer of a device according to an exemplary embodiment;

[0066] Figure 6 yes Figure 5 A schematic exemplary cross-sectional view of the device layer along axis A1;

[0067] Figure 7 This is a schematic exemplary cross-sectional view of a miniature mirror device according to an exemplary embodiment;

[0068] Figure 8A yes Figure 5 A schematic exemplary cross-sectional view along axis A1 of an exemplary device layer in an exemplary vibration state about axis A2 in an exemplary transverse intrinsic mode of oscillation;

[0069] Figure 8B yes Figure 5 A schematic exemplary cross-sectional view of an exemplary device layer in an exemplary vibration state about axis A2 along axis A1 in an exemplary transverse intrinsic mode of oscillation.

[0070] Figure 8C yes Figure 5 A schematic exemplary cross-sectional view of an exemplary device layer in an exemplary vibration state about axis A2 along axis A1 in the sixth transverse eigenmode of oscillation.

[0071] Figure 8D yes Figure 5 A schematic exemplary cross-sectional view of an exemplary device layer in an exemplary vibration state about axis A2 along axis A1 in the eighth transverse intrinsic mode of oscillation.

[0072] Figure 9A yes Figure 5 A schematic exemplary cross-sectional view of an exemplary device layer in an exemplary vibration state along axis A1 in a first transverse intrinsic mode of oscillation;

[0073] Figure 9B yes Figure 5 A schematic exemplary cross-sectional view of an exemplary device layer in an exemplary vibration state along axis A1 in the third transverse intrinsic mode of oscillation;

[0074] Figure 9C yes Figure 5A schematic exemplary cross-sectional view of an exemplary device layer in an exemplary vibration state along axis A1 in the fifth transverse eigenmode of oscillation;

[0075] Figure 10 The exemplary resonant frequency f of the nth eigenmode of the oscillation. n Here is a schematic example of a curve showing the amplitude as a function of frequency;

[0076] Figure 11 It is a schematic functional block diagram of a device according to some exemplary embodiments;

[0077] Figure 12 This is an exemplary flowchart illustrating a method of operating a 2D micromirror according to some exemplary embodiments;

[0078] Figure 13 This is an exemplary flowchart illustrating another method of operating a 2D micromirror according to some other exemplary embodiments;

[0079] Figure 14 This is a schematic exemplary top view of another device layer of a device according to some exemplary embodiments;

[0080] Figure 15 This is an exemplary flowchart illustrating another method of operating a 2D micromirror according to some other exemplary embodiments; and

[0081] Figure 16 This is an exemplary flowchart illustrating another method of operating a 2D micromirror according to some other exemplary embodiments. Detailed Implementation

[0082] In the following, preferred exemplary aspects and exemplary embodiments of the present disclosure will be described in more detail with reference to the accompanying drawings. Identical or similar features in the different drawings and exemplary embodiments are indicated by similar reference numerals. It should be understood that the following detailed description of various preferred exemplary aspects and preferred exemplary embodiments is not intended to limit the scope of the present disclosure.

[0083] Figure 1 This is a schematic illustration of an exemplary raster scan pattern or raster projection pattern, and includes background information. It exemplarily illustrates a raster scan pattern (or raster projection pattern) of a 2D micromirror device (e.g., operating as a scanner or projector), in which one axis operates resonantly at its corresponding resonant frequency, while another axis is quasi-statically driven at a frequency significantly lower than its corresponding resonant frequency. Quasi-static operation of one axis means that the frequency of the driving signal (i.e., the driven oscillation frequency) is equal to or lower than 10% of the resonant frequency associated with the corresponding axis.

[0084] As mentioned in the background section above, a typical drawback of this grating scanning or projection operation of micromirrors is that quasi-static operation makes it difficult to achieve a sufficient tilt angle of the oscillating mirror around the quasi-static axis, and requires considerably high actuation energy to achieve such a sufficient tilt angle. Therefore, quasi-static operation on one of the axes is quite inefficient in terms of energy consumption. Thus, in some exemplary embodiments, quasi-static operation is preferably avoided, and instead, the two axes of the 2D micromirror are operated in a resonant manner at or at least close to the corresponding resonant frequencies of both the first and second axes of the micromirror device.

[0085] Figure 2A This is a schematic illustration of an exemplary Lissajous scanning or projection pattern having similar resonant frequencies on two axes. This exemplarily illustrates a Lissajous scanning pattern (or Lissajous projection pattern) of a 2D micromirror device (e.g., operating as a scanner or projector), wherein the two axes operate resonantly at their respective resonant frequencies.

[0086] This uniformly distributed Lissajous pattern can be achieved when the two resonant frequencies of the two axes are substantially equal or at least close to each other. For example, Figure 2A Exemplary Lissajous patterns have been created using the online tool https: / / academo.org / demos / lissajous-curves / , and Figure 2A The ratio of the resonant frequencies in the Lissajous pattern is exemplarily chosen to be 10:9 (i.e., the difference between the two resonant frequencies of the two axes is approximately 10%).

[0087] Figure 2B This is a schematic illustration of another exemplary Lissajous scan or projection pattern with similar resonant frequencies on two axes. For example, Figure 2B Exemplary Lissajous patterns have been created using the online tool https: / / academo.org / demos / lissajous-curves / , and Figure 2B The ratio of the resonant frequencies in the Lissajous pattern is exemplarily chosen to be 20:19 (i.e., the difference between the two resonant frequencies of the two axes is approximately 5%).

[0088] If desired or preferred, such a uniformly distributed homogeneous Lissajous pattern can be achieved when the resonant frequencies of the two axes are substantially equal or at least close to each other (e.g., a frequency ratio of about 0.8 to 1.2, or preferably a frequency ratio of about 0.85 to 1.15, or preferably a frequency ratio of about 0.9 to 1.1).

[0089] To achieve higher scanning or projection resolution, higher operating frequencies can typically be used in micromirrors that operate resonantly. For example, resonant frequencies substantially equal to or greater than 1 kHz, up to hundreds of kHz, such as up to 200 kHz or higher, can be selected. In some exemplary embodiments, these resonant frequencies can even be selected in a substantially 1:1 ratio.

[0090] On the other hand, if different Lissajous patterns (such as more “grating-like” Lissajous patterns) are preferred, then it is preferable to provide a micromirror with a tuned resonant frequency, wherein the resonant frequency of one axis is relatively smaller than the resonant frequency of the other axis.

[0091] For example, the design of the micromirror structure can be tuned such that the resonant frequency of one axis is greater than that of the other axis, for example, such as two times or more, or even three times or more, or even higher. For example, the ratio of the resonant frequencies of the slow axis to the fast axis can be chosen to be substantially 1:2 (i.e., the resonant frequency of the oscillation around the fast axis is twice the resonant frequency of the oscillation around the slow axis), or in some other exemplary aspects, the ratio of the resonant frequencies of the slow axis to the fast axis can be chosen to be substantially 1:3, 1:4, 1:5 or lower, such as even 1:10 or lower.

[0092] Figure 3A This is a schematic illustration of an exemplary Lissajous scan or projection pattern where the resonant frequency of one axis is relatively smaller than the resonant frequency of another axis. For example, Figure 3A Exemplary Lissajous patterns have been created using the online tool https: / / academo.org / demos / lissajous-curves / , and Figure 3A The ratio of the resonant frequencies in the Lissajous pattern is exemplarily chosen to be 1:9.

[0093] Figure 3B This is a schematic illustration of another exemplary Lissajous scan or projection pattern where the resonant frequency of one axis is relatively smaller than the resonant frequency of another axis. For example, Figure 3B Exemplary Lissajous patterns have been created using the online tool https: / / academo.org / demos / lissajous-curves / , and Figure 3B The ratio of the resonant frequencies in the Lissajous pattern is exemplarily chosen to be 1:20.

[0094] To achieve higher scanning or projection resolution, higher operating frequencies can typically be used in micromirrors that operate in a resonant manner. For example, resonant frequencies that are substantially equal to or greater than 1 kHz, up to hundreds of kHz, such as up to 200 kHz or higher, can be selected.

[0095] As mentioned in the background section, for projection applications, it can be recognized that, as... Figure 2A Compared to the Lissajous pattern, which has a very uniform distribution of resonant frequencies on both axes and is exemplarily shown in 2B, some users (typically about 50% of users) exhibit a subjective user preference for images projected according to a pattern that is more like a grating.

[0096] For such users, it is generally preferable to offer different products in which the micromirror structure is designed such that the resonant frequency of the first axis is tuned to a relatively larger resonant frequency than that of the second axis, thereby producing a more "grating-like" effect, and thus a preferred Lissajous pattern, such as... Figure 3A Or the Lissajous pattern shown as an example in 3B.

[0097] However, providing different types of products to different user groups remains undesirable, and it is more preferable to find a technical solution that allows for the ability to project images (or perform scans) in different operating modes with different patterns, for example, a first type of Lissajous pattern with substantially equal frequencies on two axes (e.g., such as...). Figure 2A Or 2B), and a second type of Lissar pattern with a fast axis and a relatively slow axis, wherein the frequency of the slower axis is less than the frequency of the fast axis, for example, the ratio is 1:2 or less, such as 1:3, 1:4, 1:5 or less, such as even 1:10 or less, etc.

[0098] However, in some exemplary embodiments, it is preferred that each of the two or more operating modes still operates in a resonant manner on both axes in order to maintain energy efficiency, particularly compared to the inefficient quasi-static operation in typically known slow axes. It has been found that this can be advantageously achieved by utilizing different intrinsic vibrational modes (sometimes also called eigenmodes or natural oscillation modes) in at least one axis of the respective micromirror design.

[0099] At this point, we can exemplarily review the concept of vibration under different eigenmodes by utilizing the (lateral) intrinsic modes of a vibrating rod. The so-called eigenmodes of a vibrating rod describe the standing wave representation of the vibration shape. The characteristic equation of a vibrating rod depends on how the rod is attached or fixed on one or both sides, or whether it is not attached or fixed.

[0100] Figure 4 The diagram is a schematic and exemplary illustration of the first to tenth transverse intrinsic modes of oscillation of a vibrating rod fixed on both sides (also referred to as double-ended or end-to-end fixed rod vibration, used herein as an example for illustrative purposes only).

[0101] It should be noted that, regarding Figure 4 Clamping-clamping rod vibration, odd-numbered transverse eigenmodes ( Figure 4 The left-hand column (where n=1, 3, 5, etc.) exhibits a lateral shift in the middle position of the rod, while the lateral eigenpattern of even-numbered columns ( Figure 4 The right-hand column (where n=2, 4, 6, etc.) shows stationary nodes in the middle.

[0102] Therefore, the lateral eigenmodes with even-numbered designations have the following characteristics: the middle position of the rod does not exhibit lateral oscillating motion, but rather the middle portion of the rod performs oscillating tilting motion around the resting midpoint (node) of the rod. This also applies to the clamp-on example and to all other vibrating rods that have a clamping end, free end, or hinged end on one side and a clamping end, free end, or hinged end on the other side, as discussed in various textbooks on the physics of mechanical vibrations.

[0103] Therefore, with respect to the corresponding axis of the oscillating system, the even-numbered transverse eigenmodes in the system provide oscillating modes suitable for scanning or projecting patterns, in which the oscillating pattern has a centrally positioned mirror that performs oscillating tilting motion around the corresponding axis. Thus, even-numbered transverse eigenmodes are suitable for scanning and / or projection applications. On the other hand, odd-numbered transverse eigenmodes (where the mirror performs transverse oscillating displacement motion) can also be efficiently used for suitable applications, such as in interferometry applications.

[0104] It should also be noted that the characterization of even-numbered transverse eigenmodes as used in this disclosure refers to the following convention for eigenmode numbering, wherein the fundamental oscillation mode is numbered with number 1, i.e., in Figure 4 In n=1, where another term (not used in this disclosure) may refer to... Figure 4 The second eigenmode with n=2 is called the first overtone resonant mode. That is, according to another term, such as the term "even-numbered eigenmode" as used in this disclosure, it can be understood as an odd-numbered overtone oscillation mode. The numbering of the following modes will follow the numbering convention of eigenmodes (not the numbering convention of overtones).

[0105] Furthermore, this disclosure will adopt the following numbering paradigm for lateral intrinsic modes:

[0106] For 1D micromirror devices, where the mirror can be driven to oscillate relative to a single axis (1D), for example, in barcode scanning and / or interferometry applications, the eigenmode number refers to the transverse eigenmode in which the mirror oscillates laterally relative to that single axis. That is, other modes that may exist, such as those involving longitudinal oscillations, are ignored and not included in the numbering.

[0107] For 2D micromirror devices, where the mirrors can be driven to oscillate independently and / or simultaneously with respect to each of two axes, such as for 2D scanning and / or projection applications or interferometric applications, the transverse eigenmodes are individually numbered with respect to each axis.

[0108] Furthermore, for 2D micromirror devices, the numbering only applies to the lateral intrinsic mode, in which the mirror oscillates orthogonally with respect to the plane of the two axes, while other modes, such as parasitic modes and / or modes that include longitudinal oscillations, i.e. oscillations in the direction of the plane unfolded by the two axes, are ignored and not included in the numbering.

[0109] It should also be noted that all intrinsic modes, such as Figure 4 The eigenmodes in the diagram represent resonant modes with their respective associated resonant frequencies, where the resonant frequency values ​​do indeed increase with the increase of the eigenmode number.

[0110] For example, according to Figure 4 In an exemplary illustrative case of the clamp-grip rod, the ratio of resonant frequencies can be calculated as approximately 1 (n=1): 2.75 (n=2): 5.40 (n=3): 8.93 (n=4): 13.34 (n=5): 18:64 (n=6): 24.81 (n=7): 31.87 (n=8): 39.81 (n=9): 48.63 (n=10).

[0111] Specifically, for clamp-and-clamp rod vibration, the mode shapes of the eigenmode n of a beam of length L with a constant cross-sectional area A and mass density ρ can be written as: in, and for Each has its own associated resonant frequency. in E This represents Young's modulus, and I y This represents the area moment of inertia (also known as the area quadratic moment). These pattern shapes W n （x） yes Figure 4 The example shown is a pattern shape from n=1 to n=10.

[0112] In another exemplary case where the vibrating rod has hinged ends on both sides, the ratio of resonant frequencies can be calculated as increasing with the square of n, i.e., 1 (n=1): 4 (n=2): 9 (n=3): 16 (n=4) etc.

[0113] Specifically, for the vibration of a rod with hinged ends on both sides, the mode shape of the eigenmode n of a beam of length L and mass M can be written as: in for Each has its own associated resonant frequency. as well as for in E This represents Young's modulus, and I y It represents the area moment of inertia (also known as the area second moment).

[0114] In any case, even for more complex structures and / or attachments, the resonant frequency (natural frequency) associated with the corresponding eigenmode still increases with the increase of the eigenmode number.

[0115] In more complex systems, such as the MEMS designs exemplified below, the following principle still holds true: the value of the resonant frequency depends on the moment of inertia of the oscillating system (e.g., depending on the material distribution, such as being influenced by the structural design) and the stiffness of the springs in the oscillating system, such that these designs can be tuned by tuning the spring stiffness and / or moment of inertia to allow the design to resonate to achieve the desired value of the resonant frequency. It is also possible to selectively tune portions of the device layer structure design that affect certain eigenmodes relative to other eigenmodes, so as to tune the ratio of the resonant frequencies of different eigenmodes based on the desired target frequency ratio.

[0116] In view of the foregoing, the exemplary basic principle of this disclosure is that the device layer of a micromirror, such as a MEMS-based micromirror (1D or 2D micromirror) oscillating, for example, relative to an axis (e.g., an axis of one or more axes), can be operated to oscillate in different lateral eigenmodes (e.g., oscillating in an even-numbered eigenmode for lateral tilt oscillations in applications such as projection or scanning, or oscillating in an odd-numbered eigenmode for lateral displacement oscillations, for example, for interferometric applications).

[0117] Therefore, it has been recognized that a single micromirror device product can be provided that can operate resonantly at substantially two or more different resonant frequencies on at least one axis, the two or more different resonant frequencies being associated with corresponding different transverse eigenmodes associated with the respective axes, thereby enabling the same micromirror to have at least two efficient resonant operating modes suitable for different applications and / or different functions.

[0118] Therefore, the same micromirror device can operate at two or more different resonant frequencies on at least one axis, and can also be exemplarily switched between different intrinsic modes / resonant frequencies, for example, to provide different scanning or projection patterns using the same device according to user preferences and / or application requirements.

[0119] The principle of this operation will be explained below with reference to an exemplary 2D micromirror design.

[0120] It should be noted that this principle can be applied to a wide variety of micromirror designs, and the following structural aspects of the micromirror design are described merely as examples for illustrative purposes. In particular, this principle can also be widely applied to 1D micromirror designs, such as for 1D barcode scanning applications.

[0121] Figure 5 This is a schematic exemplary top view of the device layer 100 of a device according to an exemplary embodiment of the exemplary micromirror structure 10. The device layer 100 exemplary includes a frame 110, which exemplary serves as a rigid frame for the structure 10.

[0122] In the middle of the micromirror structure 10, the device layer 100 exemplarily includes a mirror support member 170, which exemplarily supports the mirror 300 (the mirror is formed, for example, by a mirror layer formed on or above the mirror support member 170 of the device layer 100).

[0123] Structure 10 is exemplarily configured to enable actuated oscillations of mirror 300 about two axes A1 and A2, driven by actuators 211 to 214 of actuator layer 200. In some exemplary embodiments, such actuators 211 to 214 may be implemented as piezoelectric actuators, for example, formed of or through a piezoelectric material, such as through a structured piezoelectric layer disposed on device layer 100. However, additionally or alternatively, other types of actuators may also be used, such as electromagnetically actuated comb structures, capacitor-based actuators, and / or other types of actuators known in MEMS technology.

[0124] For example, actuators 211 to 214 are arranged on corresponding blade portions 121 to 124 of the blade structure 120 of the device layer 100, which are connected to the frame 110 on opposite sides, thereby providing an anchoring portion for an internal movable portion of the device layer 100, which is held at the anchoring portion by the external rigid frame 110.

[0125] The blade portions 121 to 124 of the blade structure 120 of the device layer 100 can be used as an oscillating lever, which is rigidly connected to the frame 110 on one side and can undergo a certain oscillating deformation on the side facing the inner portion of the device layer 100.

[0126] The endoscope support member 170 of the device layer 100 is exemplarily connected to an exemplary closed inner frame portion 140 of the device layer 100, which is exemplarily surrounding the endoscope support member 170 of the device layer 100, via spring portions 161 and 162 of the inner spring structure 160 of the device layer 100.

[0127] For example, spring portions 161 and 162 of the inner spring structure 160 of the device layer 100 are arranged on opposite sides of the endoscope support member 170 of the device layer 100, and spring portions 161 and 162 extend for example along axis A2.

[0128] For example, the spring portions 161 and 162 of the inner spring structure 160 of the device layer 100 are in Figure 5 It is provided as a longitudinal torsion spring, but other spring shapes and types, such as, for example, double torsion springs or zigzag springs, may be used alternatively or additionally.

[0129] The inner frame portion 140 of the device layer 100 is exemplarily connected to the corresponding blade portions 121 to 124 of the blade structure 120 of the device layer 100 via the spring portions 131 and 132 of the outer spring structure 130 of the device layer 100.

[0130] For example, the spring portions 131 and 132 of the outer spring structure 130 of the device layer 100 are arranged on opposite sides of the inner frame portion 140 of the device layer 100, and the spring portions 131 and 132 of the outer spring structure 130 of the device layer 100 extend exemplarily along axis A1.

[0131] For example, the spring portions 131 and 132 of the outer spring structure 130 are in Figure 5 The spring is provided as a T-shaped torsion spring, but other spring shapes and types, such as double torsion springs or zigzag springs, may be used alternatively or additionally.

[0132] The driven oscillation of mirror 300 about axis A1 can be actuated, for example, by the following means: Figure 5 Actuators 211 and 212 on the right side of axis A1 are relative to Figure 5 The actuators 213 and 214 on the left side of axis A1 are driven in opposite phase. Preferably, due to energy efficiency, the oscillation around axis A1 is driven substantially at the corresponding resonant frequency of structure 10 associated with the oscillation around axis A1.

[0133] On the other hand, the driven oscillation of mirror 300 about axis A2 can be actuated in the following way: Figure 5 Actuators 211 and 213 on the lower side of axis A2 in the middle are relative to Figure 5 The actuators 212 and 214 on the upper side of axis A2 are driven in opposite phase. Preferably, due to energy efficiency, the oscillation around axis A2 is driven substantially at the corresponding resonant frequency of structure 10, which is associated with the oscillation around axis A2.

[0134] As described above, oscillations relative to each of axes A1 and A2 can be driven independently. Furthermore, by individually (independently) actuating the four actuators 211 to 214 using corresponding drive signals and by appropriately modulating the corresponding drive signals, both axes A1 and A2 can be operated simultaneously, for example, causing mirror 300 to oscillate approximately around axis A1 at the resonant frequency of axis A1 and approximately around axis A2 at the resonant frequency of axis A2, making it possible to project or scan a Lissajous pattern using a beam of light reflected from the oscillating mirror 300, for example, making it possible to generate a pattern based on... Figure 2A , 2B Lissana pattern, 3A or 3B.

[0135] Therefore, each actuator 211 to 214 can be driven by its respective individual drive signal, which is transmitted via Figure 5 The respective signal lines 401 to 403 of the contact 400, as exemplarily shown, are provided. Such drive signals can be generated by the controller of the micromirror device (see exemplary embodiments below).

[0136] Figure 6 yes Figure 5 A schematic exemplary cross-sectional view of device layer 100 along axis A1. Exemplarily, device layer 100 is provided as a MEMS layer structure made of multiple layers, as known in MEMS technology. Exemplarily, multiple layers of the MEMS layer structure are illustrated. The layer structure of device layer 100 is not limited and can be provided in various layer configurations, such as those known in the art.

[0137] Figure 7 This is a schematic exemplary cross-sectional view of a device according to an exemplary embodiment. Device 20 includes, exemplarily, […]. Figure 6 The device 20 has a layer 100, and is exemplarily closed from the bottom side using a base member 8, and exemplarily closed from the top side using a preferably transparent top member 7. In some exemplary embodiments, the device 20 may have a low-pressure atmosphere, preferably a vacuum, inside between the base member 8 and the top member 7, so as to allow the mirror 300 of the device 20 to oscillate more efficiently.

[0138] As explained above, the tilting oscillations of mirror 300 about axis A2 (e.g., for scanning and / or projection applications) can occur in different even-numbered lateral eigenmodes of device layer 100 (as associated with axis A1, e.g., as...). Figures 8A to 8D (As shown) it operates in a resonant manner. This will be illustrated exemplarily below with respect to the lateral eigenmodes n=2, n=4, n=6 and n=8 with even numbers from the second to the eighth.

[0139] Figure 8A yes Figure 5 A schematic example cross-sectional view of an exemplary device layer 100 along axis A1, wherein the exemplary device layer 100 is in a state where the mirror 300 is oscillating exemplary about axis A2 (e.g., for scanning and / or projection applications), and is in a second transverse eigenmode of oscillation (n=2) (i.e., substantially at the resonant frequency associated with the second transverse eigenmode).

[0140] Therefore, if the mirror 300 is actuated to drive oscillations around axis A2 in the following manner: Figure 5 Actuators 211 and 213 on the lower side of the central axis A2 relative to Figure 5Actuators 212 and 214, located on the upper side of axis A2, are driven in reverse phase essentially at the resonant frequency of the second transverse eigenmode of device layer 100 associated with axis A2. Then device layer 100 will proceed according to... Figure 8A The second transverse eigenmode oscillation is exemplarily shown in the figure, and the mirror 300 is driven to perform an oscillating tilting motion about axis A2 substantially at the resonant frequency of the second transverse eigenmode.

[0141] like Figure 8A As can be seen, the second lateral intrinsic mode operates in the following manner: the actuated external portion (e.g., in Figure 8A The blade sections 123 and 124 in the background (shown by the dashed lines) move in phase with the internal oscillations of mirror 300.

[0142] Figure 8B yes Figure 5 A schematic example cross-sectional view of an exemplary device layer 100 along axis A1, wherein mirror 300 is in a state of exemplary oscillation about axis A2 in an oscillating fourth transverse eigenmode (n=4) (e.g., for scanning and / or projection applications) (i.e., essentially at the resonant frequency associated with the fourth transverse eigenmode).

[0143] Therefore, if the mirror 300 is driven to oscillate around axis A2 in the following manner: Figure 5 Actuators 211 and 213, located below axis A2, are relative to Figure 5 Actuators 212 and 214, located on the upper side of axis A2, are driven in reverse phase essentially at the resonant frequency of the fourth transverse eigenmode of device layer 100. Then, device layer 100 will operate according to... Figure 8B The fourth transverse eigenmode oscillation is exemplarily shown in the figure, and the mirror 300 is driven to oscillate and tilt around axis A2 substantially at the resonant frequency of the fourth transverse eigenmode (greater than the resonant frequency of the second transverse eigenmode).

[0144] like Figure 8B As can be seen, the fourth transverse eigenmode operates in the following manner: the actuated external portion (e.g., in...) Figure 8B The blade sections 123 and 124 in the background (shown by the dashed lines) move out of phase with the internal oscillation of mirror 300.

[0145] Figure 8C yes Figure 5 A schematic exemplary cross-sectional view of an exemplary device layer 100 along axis A1, wherein mirror 300 is in a state of exemplary oscillation about axis A2 in an oscillating sixth transverse eigenmode (n=6) (e.g., for scanning and / or projection applications) (i.e., substantially at the resonant frequency associated with the sixth transverse eigenmode).

[0146] Therefore, if the mirror 300 is driven to oscillate around axis A2 in the following manner: Figure 5 Actuators 211 and 213, located below axis A2, are relative to Figure 5 Actuators 212 and 214, located on the upper side of axis A2, are driven in reverse phase essentially at the resonant frequency of the sixth transverse eigenmode of device layer 100. Then, device layer 100 will operate according to... Figure 8C The sixth transverse eigenmode oscillation is exemplarily shown in the figure, and the mirror 300 is driven to oscillate and tilt around axis A2 at the resonant frequency of the sixth transverse eigenmode (which is greater than the resonant frequency of the fourth transverse eigenmode).

[0147] like Figure 8C As can be seen, the sixth transverse eigenmode operates in the following manner: the actuated external portion (e.g., in...) Figure 8B The blade sections 123 and 124 in the background (shown by the dashed lines) move in phase with the internal oscillations of mirror 300.

[0148] Figure 8D yes Figure 5 A schematic example cross-sectional view of an exemplary device layer 100 along axis A1, wherein mirror 300 is in a state of exemplary oscillation about axis A2 in an oscillating eighth transverse eigenmode (n=8) (e.g., for scanning and / or projection applications) (i.e., substantially at the resonant frequency associated with the eighth transverse eigenmode).

[0149] Therefore, if the mirror 300 is driven to oscillate around axis A2 in the following manner: Figure 5 Actuators 211 and 213, located below axis A2, are relative to Figure 5 Actuators 212 and 214, located on the upper side of axis A2, are driven in reverse phase essentially at the resonant frequency of the eighth transverse eigenmode of device layer 100, then device layer 100 will be driven according to... Figure 8D The eighth transverse eigenmode oscillation is exemplarily shown in the figure, and the mirror 300 is driven to perform an oscillating tilting motion about axis A2 at the resonant frequency of the eighth transverse eigenmode (greater than the resonant frequency of the sixth transverse eigenmode).

[0150] like Figure 8D As can be seen, the eighth transverse eigenmode operates in the following manner: the actuated external portion (e.g., in...) Figure 8B The blade sections 123 and 124 in the background (shown by the dashed lines) move out of phase with the internal oscillation of mirror 300.

[0151] In conjunction with the above Figures 8A to 8DExemplary uses of even-numbered lateral eigenmodes have been discussed, which can be used for tilt oscillations of the actuated mirror 300, for example, in scanning and / or projection applications. However, even-numbered lateral eigenmodes can also be used in applications where lateral displacement of the mirror 300 can be utilized, such as in interferometric applications. This will be discussed below with reference to... Figures 9A to 9C An example is shown.

[0152] More specifically, the lateral displacement oscillation of mirror 300 along a direction orthogonal to the planes of axes A1 and A2 (e.g., for interferometric applications) can resonate in different odd-numbered lateral eigenmodes of device layer 100. This will be illustrated exemplarily below with respect to the first through fifth odd-numbered lateral eigenmodes n=1, n=3, and n=5.

[0153] Figure 9A yes Figure 5 A schematic example cross-sectional view of an exemplary device layer 100 along axis A1 (e.g., for interferometric applications), wherein the exemplary device layer 100 is in an exemplary oscillation state under an oscillating first transverse eigenmode (n=1) (i.e., substantially at the resonant frequency associated with the first transverse eigenmode).

[0154] Therefore, if the driven displacement of mirror 300 is oscillating in the following manner: Figure 5 Actuators 211 and 213, located below axis A2, are relative to Figure 5 If actuators 212 and 214, located on the upper side of axis A2, are driven in phase essentially at the resonant frequency of the first lateral intrinsic mode of device layer 100, then device layer 100 will drive according to... Figure 9A The first transverse eigenmode oscillation is exemplarily shown in the figure, and the mirror 300 is driven to perform an oscillating displacement motion substantially at the resonant frequency of the first transverse eigenmode (which is less than the resonant frequency of the second transverse eigenmode) (along a direction orthogonal to the plane of axes A1 and A2).

[0155] like Figure 9A As can be seen, the first lateral intrinsic mode operates in the following manner: the actuated external portion (e.g., in Figure 9A The blade portions 123 and 124 in the background (shown by the dashed lines) move in phase with the internal displacement oscillation of mirror 300.

[0156] Figure 9B yes Figure 5 A schematic example cross-sectional view of an exemplary device layer 100 along axis A1, wherein the exemplary device layer 100 is in an exemplary oscillating state under an oscillating third transverse eigenmode (n=3) (e.g., for interferometric applications).

[0157] Therefore, if the driven displacement of mirror 300 is oscillating in the following manner: Figure 5 Actuators 211 and 213, located below axis A2, are relative to Figure 5 Actuators 212 and 214, located on the upper side of axis A2, are driven in phase essentially at the resonant frequency of the third transverse eigenmode of device layer 100. Then, device layer 100 will operate according to... Figure 9B The third transverse intrinsic mode oscillation is exemplarily shown in the figure, and the mirror 300 is driven to perform an oscillating displacement motion substantially at the resonant frequency of the third transverse intrinsic mode (greater than the resonant frequencies of the first and second transverse intrinsic modes, and less than the resonant frequency of the fourth transverse intrinsic mode) (along a direction orthogonal to the plane of axes A1 and A2).

[0158] like Figure 9B As can be seen, the third transverse intrinsic mode operates in the following manner: the actuated external part (e.g., in Figure 9B The blade portions 123 and 124 in the background (shown by the dashed lines) move in opposite phase to the internal displacement oscillation of mirror 300.

[0159] Figure 9C yes Figure 5 A schematic example cross-sectional view of an exemplary device layer 100 along axis A1, wherein the exemplary device layer 100 is in an exemplary oscillating state under the fifth transverse eigenmode (n=5) of oscillation (e.g., for interferometric applications).

[0160] Therefore, if the driven displacement of mirror 300 is oscillating in the following manner: Figure 5 Actuators 211 and 213, located below axis A2, are relative to Figure 5 Actuators 212 and 214, located on the upper side of axis A2, are driven in phase essentially at the resonant frequency of the fifth transverse eigenmode of device layer 100. Then, device layer 100 will operate according to... Figure 9C The fifth transverse intrinsic mode oscillation is exemplarily shown in the figure, and the mirror 300 is driven to perform an oscillating displacement motion (along a direction orthogonal to the plane with axes A1 and A2) substantially at the resonant frequency of the fifth transverse intrinsic mode (greater than the resonant frequencies of the third and fourth transverse intrinsic modes, and less than the resonant frequency of the sixth transverse intrinsic mode).

[0161] like Figure 9C As can be seen, the fifth transverse eigenmode operates in the following manner: the actuated external portion (e.g., in...) Figure 9A The blade portions 123 and 124 in the background (shown by the dashed lines) move in phase with the internal displacement oscillation of mirror 300.

[0162] Figure 10The exemplary resonant frequency f of the nth eigenmode of the oscillation (where n = 1, 2, 3, ... or a higher positive integer) is... n Here is a schematic example of a curve showing the amplitude as a function of frequency.

[0163] As described above and below, in some exemplary aspects, operating a micromirror involves essentially operating at a resonant frequency f associated with the nth transverse eigenmode. n Drive at least one nth transverse eigenmode. This provides the following benefits: sufficiently large oscillation amplitudes can be achieved very efficiently due to resonant operation.

[0164] Figure 10 The curve is an illustrative example, showing the resonant frequency f. n The drive signal achieves the highest amplitude A MAX,n (This is true at least in a localized range of the spectrum, because the maximum amplitude may differ at different resonant frequencies.) For frequencies (locally) below or less than the resonant frequency f... n The frequency of the reduced driven amplitude, such as Figure 10 As exemplarily shown in the example.

[0165] Figure 10 It can be used to show the quality factor QF n It is defined as the resonant frequency value and the resonant frequency f. n The ratio of the full width of the surrounding frequency curve at the height of this curve, at that height, the amplitude relative to the (local) amplitude maximum value A. MAX，n It was reduced by half, that is, in A MAX，n The area at half height (FWHM) is called FWHM (Full Width at Half Height).

[0166] When basically at the resonant frequency f n When driving a micromirror, in order to efficiently achieve a sufficient amplitude value, it is preferable that the driving frequency is sufficiently close to the corresponding resonant frequency f. n The resonant frequency f n It can be relative to the corresponding resonant frequency f n To define (e.g., drive frequency f) D At interval f n • (1 ± q), where q is preferably 0, 1 or lower.

[0167] More preferably, the driving frequency f D It can be determined based on the corresponding resonant frequency f. n The corresponding quality factor QF n Choose one.

[0168] Preferably, in some exemplary aspects, according to this disclosure, driving a micromirror (or one of its axes) substantially at a corresponding resonant frequency can mean that, based on the corresponding resonant frequency f of the selected eigenmode to be driven... n Related quality factor QF n To select the drive frequency f D For example, as follows:

[0169] Preferably, when the micromirror device is driven substantially at the resonant frequency, this can preferably mean that p is equal to 1 or greater, such as p ≥ 1, or more preferably p ≥ 2, or even more preferably p ≥ 3 (see, for example...). Figure 10 (Example).

[0170] In this exemplary case, the driving frequency can preferably be selected within the following range:

[0171] like Figure 10 As exemplified in the example, this corresponds to the resonant frequency f relative to the selected nth transverse eigenmode to be driven. n The driving frequency f used in the following range D :

[0172] Figure 11 This is a schematic functional block diagram of a device 20 according to some exemplary embodiments. Exemplarily, the device 20 includes a micromirror 10 and a controller 30 configured to drive the micromirror device 10.

[0173] The controller 30 may, by way of example, include a processor and / or a microchip and / or a memory, which includes software and / or software for performing control functions. Therefore, the controller 30 may include hardware and / or software implementations of control functions that will be performed by the controller 30 to control the operation of the device 20, including controlling the operation of the micromirror.

[0174] The micromirror device 10 exemplarily includes actuators 211 to 214, and can be adapted to... Figures 5 to 7 The exemplary configuration or other exemplary implementation is provided, and in other exemplary implementations, the mirror 300 can be driven to oscillate about two axes (exemplary 2D micromirrors), for example, as described below. Figure 14 As exemplarily shown in the example.

[0175] In addition, the device 20 may include, for example, a light source 40 (e.g., a laser) configured to direct a light beam (e.g., a laser beam or multiple laser beams) onto a mirror 300 of a micromirror device for applications such as scanning applications (1D and / or 2D), projection applications (2D), and / or interferometry applications (1D and / or 2D).

[0176] The controller 30 exemplarily includes axis drive signal generators 701 and 702. Exemplarily, axis drive signal generator 701 is configured to generate a drive signal for oscillation of one axis of the micromirror device 10, and exemplary drive signal generator 702 is configured to generate a drive signal for oscillation of another axis of the micromirror device 10.

[0177] Exemplarily, the controller 30 also includes a switch 800 configured to switch between two or more operating modes of the device 20. Exemplarily, the two or more operating modes of the device 20 are associated with different operating modes in which different intrinsic vibration modes are actuated for at least one axis of the micromirror device 10, for example, to generate different Lissajous patterns in scanning or projection applications of the device 20 (e.g., in 2D scanning and / or 2D projection applications).

[0178] In the case of 1D applications, this allows single-axis operation to switch between different resonant operating frequencies for 1D scanning applications (and / or 1D interferometry applications).

[0179] Based on the above, at least one of the axes(s) of the micromirror device 10 can be operated to oscillate at different associated resonant frequencies of the respective transverse eigenmodes in at least two even-numbered transverse eigenmodes (e.g., as described above). Figures 8A to 9C wait).

[0180] For example, the axis drive signal generator 701 is configured to generate a drive signal for an oscillation of one of the axes of the micromirror device 10, the oscillation being substantially at the resonant frequency of the even-numbered lateral intrinsic mode of the corresponding axis, or substantially at the resonant frequency of the other even-numbered lateral intrinsic mode of the corresponding axis, depending on the operating mode set by the switch 800.

[0181] In some exemplary embodiments, switch 800 may be implemented by mechanical and / or electrical switches or other types of switches. In some other exemplary embodiments, switch 800 may be implemented by hardware and / or software, such as using registers or memories that store computer-readable information according to a selected operating mode.

[0182] In some exemplary embodiments, the switch 800 is configured to switch between two or more operating modes on the first axis of the micromirror 10 of the device 20 and / or between two or more operating modes on the second axis of the micromirror 10 of the device 20.

[0183] For example, two or more operating modes of the first axis are associated with different operating modes in which different lateral intrinsic vibration modes are actuated for the first axis of the micromirror device 10, and / or two or more operating modes of the second axis are associated with different operating modes in which different lateral intrinsic vibration modes are actuated for the second axis of the micromirror device 10.

[0184] For example, the axis drive signal generator 701 is configured to generate a drive signal for oscillation of a first axis of the micromirror device 10, the oscillation being substantially at the resonant frequency of an even-numbered eigenmode of the first axis, or substantially at the resonant frequency of another even-numbered eigenmode of the first axis, depending on the operating mode set by the switch 800.

[0185] For example, the axis drive signal generator 702 is configured to generate a drive signal for oscillation of the second axis of the micromirror device 10, the oscillation being substantially at the resonant frequency of the even-numbered eigenmode of the second axis, or substantially at the resonant frequency of another even-numbered eigenmode of the second axis, depending on the operating mode set by the switch 800.

[0186] As further exemplarily, the controller 30 includes an actuator signal generator 600 configured to generate actuator drive signals for actuators 211 to 214 of the micromirror device 10 based on an axis drive signal from an axis drive signal generator 701.

[0187] For example, according to Figure 5 An exemplary configuration drives oscillations about a first axis A1 by driving actuators 211 and 212 in opposite phase to actuators 213 and 214, and drives oscillations about a second axis A2 by driving actuators 211 and 213 in opposite phase to actuators 212 and 214.

[0188] Therefore, in order to generate a drive signal for actuator 211, actuator signal generator 600 can generate a signal that combines the drive signals from axis drive signal generators 701 and 702, and in order to generate a drive signal for actuator 214, actuator signal generator 600 can generate a signal that combines a signal that is inverted with the corresponding drive signals from axis drive signal generators 701 and 702, respectively.

[0189] In order to generate a drive signal for actuator 212, actuator signal generator 600 can generate a signal that combines a drive signal from axis drive signal generator 701 with a drive signal from axis drive signal generator 702 inverted phase. In order to generate a drive signal for actuator 213, actuator signal generator 600 can generate a signal that combines a drive signal from axis drive signal generator 701 inverted phase with a drive signal from axis drive signal generator 702.

[0190] The drive signal generated by the actuator signal generator 600 can be output to the actuators 211 to 214 via the signal output terminals 501 to 504 of the controller 20. The signal output terminals 501 to 504 are respectively connected to the connecting lines 401 to 404, and the connecting lines 401 to 404 are respectively connected to the actuators 211 to 214.

[0191] In some exemplary embodiments, the controller 30 may be configured to drive operation according to one or more of the following exemplary operation methods.

[0192] Figure 12 This is an exemplary flowchart illustrating a method of operating a 2D micromirror 10 according to some exemplary embodiments, for example, for 2D scanning or projection applications.

[0193] Exemplarily, the method includes steps S101 and S102, in which the first axis of the 2D micromirror 10 is driven resonantly at essentially the resonant frequency of the first axis of the 2D micromirror 10, and in which the second axis of the 2D micromirror 10 is driven resonantly at essentially the resonant frequency of the second axis of the 2D micromirror 10. This is exemplarily referred to as a first operating mode.

[0194] For example, in the first operating mode, the resonant frequency of the second axis of the 2D micromirror 10 is the resonant frequency of the nth transverse eigenmode of the second axis (e.g., n is an even number, such as n = 2, 4, 6, 8 or higher; see, for example, see...). Figures 8A to 8D (Example), and in step S102, the second axis can be driven substantially at the resonant frequency of the nth transverse eigenmode of the second axis.

[0195] Therefore, by reflecting the light beam onto the oscillating mirror of the micromirror 10 driven according to S101 and S102, the 2D driven oscillation on the first and second axes of the micromirror 10 is adapted to generate a first type of Lissajous pattern; for example, see step S103, when the micromirror is driven in the first operating mode, projection or scanning is performed according to the first Lissajous pattern.

[0196] For example, the method further includes step S104 of switching from a first operating mode to a second operating mode.

[0197] For example, when switching to the second operating mode in step S104, the method includes step S105, driving the first axis of the two axes of the 2D micromirror 10 in a resonant manner, substantially at the resonant frequency of the first axis of the 2D micromirror 10. In some exemplary embodiments, the first axis may operate substantially at the same resonant frequency in both operating modes, for example, in both steps S101 and S105.

[0198] For example, when switching to the second operating mode in step S104, the method includes step S106, which essentially drives the second axis of the 2D micromirror 10 in a resonant manner at another resonant frequency of the second axis of the 2D micromirror 10. This is exemplarily referred to as the second operating mode.

[0199] For example, in the second operating mode, the resonant frequency of the second axis of the 2D micromirror 10 is the resonant frequency of the m-th transverse eigenmode of the second axis (e.g., m is an even number, such as m = 2, 4, 6, 8 or higher; see, for example, see...). Figures 8A to 8D Examples; however, m is different from n in the first operating mode), and in step S106, the second axis can be driven essentially at the resonant frequency of the mth transverse eigenmode of the second axis.

[0200] Therefore, by reflecting the light beam onto the oscillating mirror of the micromirror 10 driven according to S105 and S106, the 2D driven oscillation on the first and second axes of the micromirror 10 is adapted to generate a second type of Lissajous pattern that is different from the first type of Lissajous pattern; for example, see step S107, when the micromirror is driven in the second operating mode, projection or scanning is performed according to the second Lissajous pattern.

[0201] In some exemplary embodiments, the micromirror can be tuned such that the resonant frequency of the first axis (steps S101 and S105) is similar to the resonant frequency of the second axis in the first operating mode (step S102), preferably with a difference substantially equal to or less than 20%, or even more preferably substantially equal to or less than 10%, or substantially equal to the resonant frequency of the second axis in the first operating mode (step S102), such that step S103 produces a uniform Lissajous pattern, such as Figure 2A and Figure 2B As shown.

[0202] Subsequently, in an exemplary embodiment where m is less than n, such as n=4 and m=2, or n=6 and m=2, or n=6 and m=4, the second axis is driven in the second operating mode at a smaller (i.e. slower) frequency (essentially in a resonant manner) compared to the operation in the first operating mode.

[0203] Alternatively, in an exemplary embodiment where m is greater than n, for example, n=2 and m=4, or n=2 and m=6, or n=4 and m=2, the second axis is driven in the second operating mode (in a substantially resonant manner) at a higher (i.e., faster) frequency compared to operation in the first operating mode.

[0204] In both cases, the second operating mode involves driven oscillations in which the driving frequencies of the first and second axes are relatively different, and step S107 produces a Lissajous pattern that is more like a grating (such as...). Figure 3A and Figure 3B ).

[0205] In some other exemplary embodiments, the micromirror can be tuned such that the resonant frequency of the first axis (steps S101 and S105) is similar to the resonant frequency of the second axis in the second operating mode (step S106), preferably with a difference substantially equal to or less than 20%, or even more preferably substantially equal to or less than 10%, or substantially equal to the resonant frequency of the second axis in the second operating mode (step S106), such that step S107 produces a uniform Lissajous pattern, such as Figure 2A and Figure 2B As shown.

[0206] Subsequently, in an exemplary embodiment where m is less than n, such as n=4 and m=2, or n=6 and m=2, or n=6 and m=4, the second axis is driven in the first operating mode (in a substantially resonant manner) at a higher (i.e., faster) frequency compared to the operation in the second operating mode.

[0207] Alternatively, in an exemplary embodiment where m is greater than n, such as n=2 and m=4, or n=2 and m=6, or n=4 and m=2, the second axis is driven in the first operating mode (in a substantially resonant manner) at a smaller (i.e., slower) frequency compared to operation in the first operating mode.

[0208] In both cases, the first operating mode involves driven oscillations in which the driving frequencies of the first and second axes are relatively different, and step S103 produces a Lissajous pattern that is more like a grating (such as...). Figure 3A and Figure 3B ).

[0209] In some other exemplary embodiments, it is possible to switch from a first operating mode to a second operating mode and / or switch back to the first operating mode, or vice versa.

[0210] For example, in projection applications where micromirrors are used to project images, this switching between operating modes can be performed for different purposes to switch between different types of Lissajous patterns while maintaining essentially efficient resonant operation to drive both axes.

[0211] For example, in some exemplary embodiments, user-selectable options may be provided, allowing the user to switch between a first operating mode and a second operating mode to select an image projection pattern that provides a subjectively better viewing experience. For example, physical switches or buttons and / or user-selectable interface options may be provided to the user, such as through a menu screen, enabling the user to switch between the first and second operating modes and / or to select the operating mode to use (e.g., by setting a user-preferred operating mode).

[0212] Alternatively or additionally, in some exemplary embodiments, the operating mode can be switched according to the aspect ratio of the projected image, for example, when the first Lisajous pattern of step S103 is optimized for a first aspect ratio of the projected image, and the second Lisajous pattern of step S107 is optimized for a different second aspect ratio of the projected image.

[0213] Alternatively or additionally, in some exemplary embodiments, the operating mode can be switched according to the projection type, for example, when the first Lissajous pattern of step S103 is optimized for projecting still images (such as menu screens, photos, etc.), and the second Lissajous pattern of step S107 is optimized for different projection types, such as when the second Lissajous pattern of step S107 is optimized for projecting movies or other types of video.

[0214] Alternatively or additionally, in some exemplary embodiments, the operating mode can be switched according to the projection type, for example, when the first Lissajous pattern of step S103 is optimized for a first projection frame rate, and the second Lissajous pattern of step S107 is optimized for a different second frame rate (greater or less than the first frame rate).

[0215] Alternatively or additionally, in some exemplary embodiments, the operating mode may be switched according to the desired image resolution of the projected image, for example, when the first Lisajous pattern of step S103 is optimized for the projected image resolution, and the second Lisajous pattern of step S107 is optimized for different second image resolutions (greater or less than the first image resolution).

[0216] When combining the above examples, it may be advantageous, according to some exemplary embodiments, to provide switching between three or more operating modes, wherein, in each of the different operating modes, the second axis is driven in a different lateral intrinsic mode.

[0217] Furthermore, not only can the second axis be operated in different lateral eigenmodes, but the first axis can also be additionally switched between different lateral eigenmodes, such as in combination with... Figure 13 Exemplary examples are shown to provide additional options for two or more operating modes using the same micromirror device (where both axes operate in a highly efficient resonant manner).

[0218] Figure 13 This is an exemplary flowchart illustrating another method of operating the 2D micromirror 10 according to some other exemplary embodiments, such as for 1D or 2D scanning applications, 2D projection applications and / or 1D or 2D interferometry applications.

[0219] Here, although exemplary Figure 12 This only involves 2D scanning or projection applications, but Figure 13 A broader concept is described regarding 1D or 2D scanning applications, 2D projection applications, and / or 1D or 2D interferometry applications. In the case of 1D applications, the additional axis may not be present, and for 2D applications, another second axis may be driven as explained in other exemplary embodiments.

[0220] Exemplarily, the method includes step S102a, which essentially drives one of one or more axes of the micromirror in a resonant manner at the resonant frequency of the axis of the micromirror. This is exemplarily referred to as a first operating mode.

[0221] For example, in step S102a, in the first operating mode, the driving frequency of the axis of the micromirror is essentially the resonant frequency of the nth transverse eigenmode of that axis (e.g., n is an even number, such as n = 2, 4, 6, 8 or higher; see example...). Figures 8A to 8D Examples; or n is an odd number, such as n=1, 3, 5, 7 or higher; see, for example Figures 9A to 9C (Example).

[0222] Therefore, by step S103a, which involves reflecting the light beam onto the oscillating mirror of the micromirror 10 driven according to S102a, the selected application can be operated when the micromirror is driven in the first operating mode. That is, in the exemplary case of 1D, even-numbered n, such as n=2, 4, 6, 8 or higher, allows 1D scanning applications, and odd-numbered n, such as n=1, 3, 5, 7 or higher, allows interferometric applications.

[0223] For example, the method further includes step S104a of switching from a first operating mode to a second operating mode.

[0224] For example, when switching to the second operating mode in step S104a, the method includes step S106a, which essentially drives the axis of the micromirror in a resonant manner at another resonant frequency of the axis of the micromirror. This is exemplarily referred to as the second operating mode.

[0225] For example, in step S106a, in the second operating mode, the driving frequency of the axis of the micromirror is essentially the resonant frequency of the m-th transverse eigenmode of that axis (e.g., m is an even number, such as m = 2, 4, 6, 8 or higher; see example...). Figures 8A to 8D Examples; or m is an odd number, such as m = 1, 3, 5, 7 or higher; see examples Figures 9A to 9C Examples; but m is different from n in the first operating mode).

[0226] Therefore, by step S107a, which involves reflecting the light beam onto the oscillating mirror of the micromirror 10 driven according to S106a, the selected application can be operated when the micromirror is driven in the second operating mode. That is, in the exemplary case of 1D, even-numbered m, such as m=2, 4, 6, 8 or higher, allows 1D scanning applications, while odd-numbered m, such as m=1, 3, 5, 7 or higher, allows interferometric applications.

[0227] This allows switching between different effective resonant operating modes driven at substantially different resonant frequencies within the same application (e.g., scanning, projection, or interferometry). Furthermore, this also allows switching between different applications, including between projection / scanning and interferometry applications, and vice versa, when switching from odd-numbered modes to even-numbered modes.

[0228] Figure 14 This is a schematic exemplary top view of another device layer 100 of a device according to some exemplary embodiments.

[0229] Figure 14 The exemplary device layer 100 is similar to the above. Figure 5 The device layer 100. However, although Figure 5 The blade portions 121 to 124 are exemplarily anchored to the frame 110 on opposite sides relative to axis A2, but Figure 14 The blade portions 121 to 124 are exemplary anchored to the frame 110 on opposite sides relative to axis A1, and have portions extending toward attachment positions of springs 131 and 132 in the direction of axis A2.

[0230] Therefore, when actuators 211 and 213 are actuated in phase or out of phase with actuators 212 and 214, the lateral intrinsic modes associated with axis A1 (e.g., similar to) can be actuated. Figures 8A to 9C Subsequently, the structures of springs 131 and 132 and the inner frame portion 140 oscillate in a mode shape of transverse intrinsic mode associated with axis A1 (e.g., similar to...). Figures 8A to 9C ).

[0231] On the other hand, exemplarily, when actuators 211 and 212 are actuated in phase or out of phase with actuators 213 and 214, the transverse intrinsic mode associated with axis A2 can be actuated. Subsequently, the structure of blade portions 121 to 124, particularly the portion extending along axis A2, can oscillate in a mode shape of the transverse intrinsic mode associated with axis A2 (e.g., similar to...). Figure 4 (pattern shape).

[0232] Further exemplarily, when both axes A1 and A2 are driven in their respective even-numbered lateral eigenmodes, this allows for 2D scanning or projection applications. On the other hand, further exemplarily, when both axes A1 and A2 are driven in their respective odd-numbered lateral eigenmodes, this allows for interferometric applications via mirror 300 performing shift oscillations in a direction orthogonal to the planes of axes A1 and A2. Therefore, this allows switching between different scans (projection patterns) and also between different interferometric application modes with different efficient resonant operating frequencies. Further exemplarily, this allows switching between 2D scanning / projection applications and interferometric applications on the same micromirror device.

[0233] Figure 15 This is an exemplary flowchart illustrating another method of operating the 2D micromirror 10 according to some other exemplary embodiments.

[0234] Exemplarily, the method includes steps S111 and S112, in which the first axis of the 2D micromirror 10 is driven resonantly at essentially the resonant frequency of the first axis of the 2D micromirror 10, and in which the second axis of the 2D micromirror 10 is driven resonantly at essentially the resonant frequency of the second axis of the 2D micromirror 10. This is exemplarily referred to as a first operating mode.

[0235] For example, in step S111, the resonant frequency of the first axis of the 2D micromirror 10 in the first operating mode is substantially the resonant frequency of the kth eigenmode of the first axis (e.g., k with an even number, such as k=2, 4, 6, 8 or higher; or k with an odd number, such as k=1, 3, 5, 7 or higher), and in step S112, the second axis can be driven substantially at the resonant frequency of the nth eigenmode of the second axis (e.g., n with an even number, such as n=2, 4, 6, 8 or higher; or n with an odd number, such as n=1, 3, 5, 7 or higher).

[0236] Therefore, by reflecting the light beam onto the oscillating mirror of the micromirror 10 driven according to S111 and S112, if n and k are even numbers, the 2D driven oscillation on the first and second axes of the micromirror 10 is adapted to generate a first type of Lissajous pattern; for example, see step S113, when the micromirror is driven in the first operating mode, projection or scanning is performed according to the first Lissajous pattern. Alternatively, if n and k are odd numbers, an interferometric application can be performed.

[0237] For example, the method further includes step S114 of switching from a first operating mode to a second operating mode.

[0238] Exemplarily, in steps S115 and S116 of driving the first and second axes in the second operating mode, in step S115, the resonant frequency of the first axis of the 2D micromirror 10 in the second operating mode is substantially the resonant frequency of the i-th eigenmode of the first axis (e.g., i with an even number, such as i = 2, 4, 6, 8 or higher; or i with an odd number, such as i = 1, 3, 5, 7 or higher; i is different from k), and in step S116, the second axis can be driven substantially at the resonant frequency of the m-th eigenmode of the second axis (e.g., m with an even number, such as m = 2, 4, 6, 8 or higher; or m with an odd number, such as m = 1, 3, 5, 7 or higher; m is different from n). This is exemplarily referred to as the second operating mode.

[0239] Therefore, by reflecting the light beam onto the oscillating mirror of the micromirror 10 driven according to S115 and S116, if m and i are even-numbered, the 2D driven oscillation on the first and second axes of the micromirror 10 is adapted to generate a second type of Lissajous pattern different from the first type of Lissajous pattern; for example, referring to step S117, when the micromirror is driven in the second operating mode, projection or scanning is performed according to the second Lissajous pattern. Alternatively, if m and i are odd-numbered, an interferometric application can be performed.

[0240] Exemplary, in some exemplary embodiments, the micromirror can be tuned such that the resonant frequencies of the first and second axes are similar (preferably, the difference is substantially equal to or less than 20%, or even more preferably, substantially equal to or less than 10%) or substantially equal in the first operating mode, such that step S113 produces a uniform Lissajous pattern (such as...). Figure 2A and Figure 2B ), and / or the micromirrors can be tuned such that the resonant frequencies of the first and second axes are similar or substantially equal in the second operating mode, such that step S117 produces a uniform Lissajous pattern (such as Figure 2A and Figure 2B In another operating mode, if needed, a second type of more raster-like Lissajous pattern can be provided (such as, for example, in...). Figure 3A and Figure 3B middle).

[0241] Here, in some exemplary embodiments, for example, if the first operating mode provides a uniform Lissajous pattern type through similar or substantially similar resonant frequencies of the k-th eigenmode of the first axis and the n-th eigenmode of the second axis, then if the axes are switched in opposite directions, for example, if k > i and n < m, or vice versa, i.e. k m, then a second type of Lissajous pattern, even more like a grating, can be provided in the second operating mode.

[0242] In the preceding text, it was assumed that the micromirror operates in two modes and switches between them. In some other exemplary embodiments, a default operating mode may be pre-selected during a setup operation (e.g., during user setup and / or when selecting a menu option that enables user settings), see, for example... Figure 16 .

[0243] Figure 16 This is an exemplary flowchart illustrating another method of operating the 2D micromirror 10 according to some other exemplary embodiments.

[0244] The method exemplarily includes step S121 of selecting an operating mode among different operating modes, such as the first and second operating modes (or more than two operating modes) discussed above, wherein the operating mode is preferably selectable by the user.

[0245] In other words, during the initial setup of the device and / or when the user activates the operation selection function in the user menu screen, the user can select a preferred operation mode. In some exemplary embodiments, images projected in different operation modes (e.g., according to the method described above) may be shown to the user, and / or the user can select the desired operation mode from a list of options displayed in the menu screen.

[0246] Preferably, each of the user-selectable operating modes is associated with certain intrinsic modes of the first and second axes.

[0247] When selecting, the method may include step S122, driving the first axis of the two axes of the 2D micromirror 10 substantially at the resonant frequency of the first axis of the 2D micromirror 10 in a resonant manner, based on the selected operating mode (e.g., associated with the nth eigenmode of the first axis; e.g., an even-numbered n, such as n=2, 4, 6, 8 or higher; or an odd-numbered n, such as n=1, 3, 5, 7 or higher), and step S132, driving the second axis of the two axes of the 2D micromirror 10 substantially at the resonant frequency of the second axis of the 2D micromirror 10 in a resonant manner, based on the selected operating mode (e.g., associated with the mth eigenmode of the second axis; e.g., an even-numbered m, such as m=2, 4, 6, 8 or higher; or an odd-numbered m, such as m=1, 3, 5, 7 or higher; where m is different from n).

[0248] Therefore, by reflecting the light beam onto the oscillating mirror of the micromirror 10 driven according to S122 and S123, the 2D-driven oscillations on the first and second axes of the micromirror 10 are adapted to generate a user-selected Lissajous pattern based on the selected operating mode. If m and n are selected as even numbers, the projected Lissajous pattern can preferably be different from the Lissajous pattern of the unselected operating mode; for example, referring to step S124, when the micromirror is driven in the selected operating mode, projection or scanning is performed according to the Lissajous pattern associated with the selected operating mode. Alternatively, if n and / or m are odd numbers, interferometric applications can be performed in one or both selectable operating modes.

[0249] Exemplary embodiments have been described above, which advantageously allow operation of the micromirror in different operating modes. In some exemplary aspects, this allows for different Lissajous patterns to be provided for different user preferences and / or different applications, while still allowing highly efficient operation of two or more different operating modes. Since the two axes can operate resonantly in each of the two or more operating modes, this allows for avoidance of quasi-static operation, which is significantly less efficient. In other exemplary embodiments, this concept can also be applied to interferometric applications and / or 1D scanning operations (e.g., for barcode scanning).

[0250] While certain exemplary embodiments have been described above and illustrated in the accompanying drawings, it should be understood that such embodiments are merely illustrative and not intended to limit the scope of this broad disclosure. Furthermore, the exemplary embodiments of this disclosure are not limited to the specific constructions and arrangements shown and described, as various other variations, combinations, omissions, modifications, and substitutions are possible beyond those set forth in the foregoing paragraphs. Those skilled in the art will understand that various adaptations, modifications, and / or combinations of the embodiments just described can be configured without departing from the scope of this disclosure. Therefore, it should be understood that this disclosure can be practiced in ways different from those specifically described herein within the scope of the appended claims. For example, unless expressly stated otherwise, the steps of the processes described herein may be performed in a different order than those described herein, and one or more steps may be combined, separated, or performed simultaneously. Those skilled in the art will also understand that, in view of this disclosure, different embodiments of this disclosure described herein can be combined to form other embodiments of this disclosure.

Claims

1. A method for operating a micromirror device (10), the micromirror device (10) comprising a mirror (300) configured to be driven to oscillate relative to at least a first axis (A1; A2), the method comprising: - Select an operating mode from at least two selectable operating modes of the micromirror device (10), wherein, The first of the at least two selectable operating modes is associated with an oscillation of the mirror (300) substantially at the resonant frequency of the transverse intrinsic mode of the mirror (300) associated with the first axis (A1; A2), and The second of the at least two selectable operating modes is associated with an oscillation of the mirror (300) substantially at the resonant frequency of another transverse eigenmode of the mirror (300) that is associated with the first axis (A1; A2); and - Drive the oscillation of the mirror (300) according to the selected operating mode.

2. The method according to claim 1, further comprising: When the first operating mode is selected, the mirror (300) is driven to oscillate substantially at a resonant frequency associated with the Nth transverse eigenmode of the mirror (300) that is associated with the first axis (A1; A2), according to the selected first operating mode; and / or When the second operating mode is selected, the mirror (300) is driven to oscillate substantially at the resonant frequency of another Mth transverse eigenmode of the mirror (300) associated with the first axis (A1; A2), according to the selected second operating mode.

3. The method according to claim 1 or 2, wherein, The corresponding lateral eigenmode of the selected operating mode is the even-numbered lateral eigenmode associated with the first axis (A1; A2), and The mirror (300) is driven to oscillate according to the selected operating mode in order to perform projection or scanning operations of the micromirror device (10) using a light beam reflected from the oscillating mirror.

4. The method according to claim 1 or 2, wherein, The corresponding lateral eigenmode of the selected operating mode is the odd-numbered lateral eigenmode associated with the first axis (A1; A2), and The mirror (300) is driven to oscillate according to the selected operating mode in order to perform interferometric measurement operations of the micromirror device (10) using the light beam reflected on the oscillating mirror.

5. The method according to at least one of the preceding claims, wherein, Selecting the operating mode includes switching between the first operating mode and the second operating mode.

6. The method according to claim 5, wherein, The corresponding lateral eigenmodes of the first and second operating modes are different even-numbered lateral eigenmodes associated with the first axis (A1; A2), and the switching between the first and second operating modes is a switching between two operating modes for projection or scanning operations to perform the resonant operation of the micromirror device (10) at different corresponding resonant frequencies associated with the first axis (A1; A2).

7. The method according to claim 5, wherein, The corresponding lateral eigenmodes of the first operating mode and the second operating mode are different odd-numbered lateral eigenmodes associated with the first axis (A1; A2), and the switching between the first operating mode and the second operating mode is performed between two operating modes of interferometric measurement operation for performing the resonant operation of the micromirror device (10) at different corresponding resonant frequencies associated with the first axis (A1; A2); or The corresponding lateral eigenmode of the first operating mode is an even-numbered lateral eigenmode, and the corresponding lateral eigenmode of the second operating mode is an odd-numbered lateral eigenmode. The switching between the first operating mode and the second operating mode is performed between an operating mode for projection or scanning operation for performing the resonant operation of the micromirror device (10) and an operating mode for interferometric measurement operation for performing the resonant operation of the micromirror device (10).

8. The method according to at least one of the preceding claims, wherein, The mirror (300) is configured to be driven to oscillate in two dimensions relative to the first axis (A1) and the second axis (A2), and The oscillation of the mirror (300) driven according to the selected operating mode includes: driving the mirror (300) to oscillate substantially in resonance with respect to the first axis (A1) and driving the mirror (300) to oscillate substantially in resonance with respect to the second axis (A2).

9. The method according to claim 8, wherein, The first operating mode is associated with the tilting oscillation of the mirror (300) about the second axis (A2), the tilting oscillation being driven substantially by the resonant frequency of the even-numbered Nth transverse eigenmode of the mirror (300) relative to the first axis (A1), and The second operating mode is associated with the tilt oscillation of the mirror (300) about the second axis (A2), which is driven substantially by the resonant frequency of the Mth eigenmode of another even-numbered oscillation of the mirror (300) relative to the first axis (A1).

10. The method of claim 9, further comprising: A Lissajous scan or projection pattern is generated by reflecting a light beam onto the mirror (300), while the mirror (300) is driven to oscillate around the first axis (A1) substantially at the resonant frequency of the oscillation of the mirror (300) around the first axis (A1), and the mirror (300) is driven to oscillate around the second axis (A2) according to a selected operating mode. Specifically, a first type of Lissajous pattern is generated in the first operating mode and a second type of Lissajous pattern is generated in the second operating mode.

11. The method according to at least one of claims 8 to 10, wherein, According to the first operating mode, the first ratio between the resonant frequency of the oscillation of the mirror (300) around the first axis (A1) and the corresponding resonant frequency of the oscillation of the mirror (300) around the second axis (A2) is substantially equal to or greater than 1: 1.2 and / or substantially equal to or less than 1:0.8, especially substantially equal to or greater than 1: 1.1 and / or substantially equal to or less than 1:0.9, and preferably, the first ratio is substantially 1:

1.

12. The method according to at least one of claims 8 to 11, wherein, According to the second operating mode, the second ratio between the resonant frequency of the oscillation of the mirror (300) around the first axis (A1) and the corresponding resonant frequency of the oscillation of the mirror (300) around the second axis (A2) is substantially equal to or less than 1:2, particularly substantially equal to or less than 1:3, and preferably, the second ratio is substantially equal to or less than 1:5; and / or the second ratio is substantially equal to or greater than 1:20, and preferably, the second ratio is substantially equal to or greater than 1:

10.

13. The method according to at least one of claims 8 to 12, further comprising: According to the first operating mode, the oscillation of the mirror (300) around the second axis (A2) is driven substantially at the resonant frequency of the Nth eigenmode of the oscillation of the mirror (300) around the second axis (A2), and / or according to the second operating mode, the oscillation of the mirror (300) around the second axis (A2) is driven substantially at the resonant frequency of the Mth eigenmode of the oscillation of the mirror (300) around the second axis (A2); The oscillation of the mirror (300) around the first axis (A1) is driven by the first operating mode and the second operating mode, and is performed substantially at the same resonant frequency of the transverse eigenmode of the oscillation of the mirror (300) around the first axis (A1) relative to the second axis (A2); or The oscillation of the mirror (300) around the first axis (A1) driven according to the first operating mode and the oscillation of the mirror (300) around the first axis (A1) driven according to the second operating mode are performed substantially at different resonant frequencies of different even-numbered transverse eigenmodes of the oscillation of the mirror (300) around the first axis (A1) relative to the second axis (A2).

14. An apparatus for operating a micromirror device (10), comprising: A micromirror device (10) comprising a mirror (300) configured to be driven to oscillate relative to at least a first axis (A1; A2), and a controller (30) configured to control the operation of the micromirror device (10) according to the method of at least one of the preceding claims.

15. A computer program apparatus comprising instructions that, when the program is executed by a controller of a device for operating a micromirror apparatus (10), cause the controller to perform the method according to at least one of claims 1 to 13, the micromirror apparatus (10) comprising a mirror (300) configured to be driven to oscillate relative to at least a first axis (A1; A2).

Images