Mirror arrangement and projection device

Abstract

Mirror arrangement (S), comprising a mirror (Sp, 3) which is mounted for vibration; comprising a coil (Su, 20); comprising at least one first spring (F) which couples the mirror (Sp, 3) and the coil (Su, 20) to each other in such a way that the coil (Su, 20) is arranged as a counterweight to the vibrating mirror (Sp, 3); comprising a frame (1); comprising at least one second spring (5), in particular a spring which is flexible or soft in at least one direction and which couples the frame (1) to the mirror (Sp, 3) and / or the coil (Su, 20) and / or the at least one first spring (F); comprising at least one second measuring device (M2), in particular at least one piezoresistive resistor which is configured to detect the deflection of the group from the mirror (Sp, 3) and / or the coil (Su, 20) and / or the at least one first spring (F), and which is in particular arranged on the at least one second spring (5).

Description

The present invention relates to a mirror arrangement and a corresponding projection device. State of the art Today, projectors are used in a wide variety of applications. For example, projectors can be used for presentations or to project films. Various technologies are used to project images or videos. For example, light sources can be positioned behind one or more LCD displays, through which the light passes. This allows the image displayed on the LCD screen to be projected onto a screen, for example. Alternatively, an image can be created using micromirrors. A micromirror-based projector has one or more micromirrors that are illuminated by a light source, such as a laser. To project different image content, these micromirrors are set into vibration. Depending on the amplitude of the vibration and the position of the mirror, the laser beam is either reflected onto the projection surface or not. Typically, such micromirrors are excited into resonant vibration. The excitation of the mirror occurs, for example, in an oscillating rotational motion. The oscillating rotary motion is advantageous because it allows light, for example a laser beam, to be deflected over a large area at small angles. A rotating oscillating system is used for excitation. The extraction of vibrational energy and the associated high damping of the oscillating system, which leads to increased energy consumption, are typically neglected. Excitation by external vibrations is also neglected. For example, if such a system is used in a mobile phone as a deflection unit for image generation, and a loudspeaker is active in this mobile phone at the same time (e.g. when playing video films), the loudspeaker can excite the mirror deflection unit in one of its natural modes by transmitting structure-borne sound vibrations (possibly also by air vibrations) and thus disrupt the image formation. A projection system with a resonantly excited mirror is disclosed, for example, in US 2013 / 0250388A1. Documents DE 102012208117A1, DE 102012206291A1, and US 4919500A describe mirror arrangements that partially incorporate features of the mirror arrangement according to claim 1. Disclosure of the invention The present invention discloses a mirror arrangement with the features of claim 1 and a projection arrangement with the features of claim 13. Accordingly, the following is planned: A mirror arrangement comprising a mirror mounted on a oscillating suspension, a coil and at least one first spring that couples the mirror and the coil to each other in such a way that the coil is arranged as a counterweight to the oscillating mirror. Furthermore, the following is planned: A projection device comprising a light source, at least one mirror arrangement according to the invention and a control system for controlling the at least one mirror arrangement. Advantages of the invention The underlying insight of the present invention is that known mirror arrangements inherently exhibit high attenuation, resulting in high energy consumption. Furthermore, conventional mirror arrangements are sensitive to external disturbances. The idea underlying the present invention is to take this knowledge into account and to provide a new mirror arrangement which has low energy requirements and is insensitive to external disturbances. The present invention provides a mirror arrangement comprising a mirror. A coil is coupled to this mirror via a first spring. The coil serves as a counterweight to the mirror. The mirror and the coil, which are coupled together by the first spring, form a simple resonant system in which the coil and mirror oscillate at the same frequency. The present invention offers the advantage that resonant decoupling of the simply resonant system from the surrounding assembly and interconnection technology (abbreviated AVT) or “packaging” becomes possible. Compared to, for example, known double resonant systems, the single resonant system of the present invention is insensitive to spring tolerances. Advantageous embodiments and further developments are described in the dependent claims and in the description with reference to the figures. In one embodiment, the mirror is designed to oscillate rotationally. Furthermore, the at least one first spring couples the mirror and the coil such that the coil oscillates in the opposite direction to the mirror's direction of movement. This provides a simple resonant system in a very straightforward manner. According to the invention, the mirror arrangement comprises a frame and at least one second spring, in particular a spring that is flexible or soft in at least one direction, which couples the frame to the mirror and / or the coil and / or the at least one first spring. If the mirror and / or the coil and / or the at least one first spring, i.e., the simply resonant system, is coupled to the frame via a second spring, the simply resonant system is decoupled from external mechanical conditions, particularly in the case of a soft spring. Furthermore, only a very small amount of vibrational energy is coupled into the surrounding acoustic environment. In one embodiment, the second spring is so soft that it holds the mirror and the coil in place, but has only an insignificant influence on the resonant frequency of the simply resonant system. In another embodiment, the coil comprises a coil former, in particular a coil former with a cavity, and a coil winding arranged on the coil former. The cavity makes it possible to reduce the mass of the coil former, thereby increasing the amplitude of movement of the coil former. This increases the drive efficiency. In another embodiment, the cavity has walls or ribs. The walls or ribs provide the cavity with mechanical stability if the specific application requires it. In one embodiment, the cavity at the end of the coil former can be omitted. Depending on the arrangement of the simply resonant system, a counterweight can thus be formed, which reduces the tilting motion of the coil former if it is to undergo a linear movement. In a further embodiment, the at least one first spring and the coil are arranged in a first plane. Furthermore, the mirror is arranged above the first plane in a second plane, which lies parallel to the first plane, wherein the mirror is coupled to the at least one first spring, in particular via a bridge of a predetermined length. If the mirror is arranged in the second plane while the coil lies in the first plane, and the distance between the two planes is adjusted by the bridge, the movement of the mirror can be defined very precisely. For example, it becomes possible to set the mirror into a rotational movement while the coil only undergoes an approximately linear movement. In a further embodiment, the at least one first spring has four spring arms which are meander-shaped and which are coupled to the bridge at one end. In a further embodiment, the at least one first spring has two spring arms which are circular in shape and which are coupled to the bridge at one end. In another embodiment, the spring arms are coupled at their end not connected to the bridge to a connecting element, which couples the at least one first spring to the coil. Alternatively, the spring arms are directly coupled to the coil at their end not connected to the bridge. The aforementioned configurations of the first spring enable a variable, application-specific design of the simply resonant system. In another embodiment, the second spring is designed as a leaf spring. In a further embodiment, the mirror arrangement comprises a housing that encloses at least the mirror, the coil, and the at least one first spring, wherein the housing has a lower atmospheric pressure, particularly a vacuum, than the surrounding environment and is hermetically sealed. The low atmospheric pressure facilitates the movement of the mirror and the coil. In another embodiment, the housing above the mirror is at least partially transparent to laser beams. Alternatively, the housing above the mirror has a window, in particular a window inclined relative to the first or second plane, which is transparent to laser beams. This makes it possible to use the mirror arrangement according to the invention with an external light source, e.g., a laser. Furthermore, the inclined window prevents reflections. In another embodiment, the mirror arrangement includes a magnet, in particular a permanent magnet, which is arranged on the housing such that the coil lies within the magnetic field of the magnet. This allows movement of the coil to be initiated without physical contact. In another embodiment, the mirror arrangement includes a flux guide plate which is positioned on the magnet such that the magnet's magnetic field penetrates the first plane in the coil area approximately perpendicularly or approximately horizontally. This allows the efficiency of the mirror arrangement to be optimized depending on the desired direction of movement of the coil. In a further embodiment, the mirror arrangement comprises at least one first measuring device, in particular at least one piezoresistive resistor, which is configured to detect the mirror's deflection and which is, in particular, arranged on the at least one first spring. This makes it possible to detect the mirror's movement precisely. In one embodiment, supply lines are arranged on the second spring, which supply the coil with electrical energy. This allows for easy connection of the coil to a control device or an electrical power source. According to the invention, the mirror arrangement comprises at least one second measuring device, in particular at least one piezoresistive resistor, which is configured to detect the displacement of the group from the mirror and / or the coil and / or the at least one first spring, and which is in particular arranged on the at least one second spring. This makes it possible to detect the movement of the simply resonant system of the present invention. In a further embodiment, the mirror arrangement includes a control device configured to control the coil based on the measured values ​​of at least one second measuring device, such that the group consisting of the mirror and / or the coil and / or the at least one first spring is excited at a predetermined frequency, or to control the coil in such a way that externally occurring excitations are actively counteracted. For example, image speckle can be reduced very variably. Furthermore, externally occurring excitations can be actively dampened. In another embodiment, the mirror has a base plate on the upper side of which the mirror surface is arranged and on the underside of which a stiffening element is arranged, which is designed to mechanically stabilize the mirror. This ensures that the mirror is not excessively deformed even during highly dynamic movements caused by acceleration forces. The above embodiments and further developments can be combined with one another as appropriate. Further possible embodiments, further developments, and implementations of the invention also include combinations of features of the invention described previously or subsequently with regard to the exemplary embodiments, even if not explicitly mentioned. In particular, the person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the present invention. Brief description of the drawings The present invention is explained in more detail below with reference to the exemplary embodiments shown in the schematic figures of the drawings. These show: Fig. 1 a block diagram of an embodiment of a mirror arrangement according to the invention; Fig. 2 a block diagram of an embodiment of a projection device according to the invention; Fig. 3 a schematic representation of an embodiment of a mirror arrangement according to the invention; Fig. 4 a schematic representation of an embodiment of a mirror arrangement according to the invention; Fig. 5 a schematic representation of an embodiment of a mirror arrangement according to the invention; Fig. 6 a schematic representation of an embodiment of a mirror arrangement according to the invention; Fig. 7 a schematic representation of an embodiment of a mirror arrangement according to the invention; Fig. 8 a schematic representation of an embodiment of a mirror arrangement according to the invention; Fig.Fig. 9 a schematic representation of an embodiment of a mirror arrangement according to the invention; Fig. 10 a schematic representation of an embodiment of a mirror arrangement according to the invention; Fig. 11 a schematic representation of an embodiment of a mirror arrangement according to the invention; Fig. 12 a schematic representation of an embodiment of a mirror arrangement according to the invention; Fig. 13 a schematic representation of an embodiment of a mirror arrangement according to the invention; Fig. 14 a schematic representation of an embodiment of a mirror arrangement according to the invention; Fig. 15 a schematic representation of an embodiment of a mirror arrangement according to the invention; Fig. 16 a schematic representation of an embodiment of a mirror arrangement according to the invention; Fig. 17 a schematic representation of an embodiment of a mirror arrangement according to the invention; Fig.Fig. 18 is a schematic representation of an embodiment of a mirror arrangement according to the invention; Fig. 19 is a schematic representation of an embodiment of a mirror arrangement according to the invention; Fig. 20 is a schematic representation of an embodiment of a mirror arrangement according to the invention; Fig. 21 is a schematic representation of an embodiment of a mirror arrangement according to the invention; and Fig. 22 is a schematic representation of an embodiment of a mirror arrangement according to the invention. In all figures, identical or functionally equivalent elements and devices – unless otherwise specified – have been provided with the same reference numerals. Embodiments of the invention Fig. 1 shows a block diagram of an embodiment of a mirror arrangement S according to the invention. The mirror arrangement S has a mirror Sp which is coupled to a coil Su via a spring F. The coil Su is arranged in such a way that it forms a counterweight to the mirror Sp. Fig. 2 shows a block diagram of an embodiment of a projection device P according to the invention. The projection device P has a mirror arrangement S coupled to a control unit SE. A light source L is also provided, which illuminates the mirror arrangement S. The light beam from the light source L is reflected by the mirror arrangement S. The laser is also controlled via the control unit SE, so that a laser can be controlled depending on the tilt angle of the mirror. This allows, for example, a second laser to be used to generate an image projection. Fig. 3 shows a schematic representation of an embodiment of a mirror arrangement S according to the invention. The mirror arrangement S has a frame 1 for connecting the mirror arrangement S, e.g., to a housing and the external assembly and connection technology. A coil 20 is arranged in the frame 1, comprising a coil former 2 and a coil winding 7. Furthermore, a mirror 3 is arranged in the frame 1, which is coupled to the coil 20 via the first spring F and a connecting element 14. The spring F is not shown separately. Rather, the four spring arms 4a, 4b, 4c, and 4d of the spring F are shown, which couple the mirror 3 to the connecting element 14 via a bridge 41 (see Fig. 4) and its section 40. The bridge 41 is only coupled to the four spring arms 4a, 4b, 4c, and 4d in the section 40. Furthermore, connecting bridges 45a and 45b are provided in Fig. 3, which couple the spring arms 4a and 4b and the spring arms 4c and 4d to each other, respectively. The connecting bridges are optional. The simply resonant system consisting of coil 20, mirror 3, connecting elements 14, and spring arms 4a-4d is coupled to the frame 1 via four soft springs 5, which are also meandering. Two of the springs 5 ​​are coupled to the coil former 2. Two other springs 5 ​​are coupled to the ends of the U-shaped connecting element 14, which surrounds the spring arms 4a-4d. The springs 5 ​​are so soft that they hold the mirror 3 and the coil 20 in their position but have only an insignificant influence on the resonant frequency of the oscillation of the simply resonant system. In Fig. 3, the second plane, in which the mirror 3 is arranged, is located below the first plane, in which the coil 20 and the spring arms 4a-4d are arranged. The mirror 3 is therefore located below the coil 20 and the spring arms 4a-4d. The spring arms 4a, 4b, 4c and 4d of Fig. 3 are designed in a meandering shape and extend from the web 40, which lies in the middle of the four spring arms 4a, 4b, 4c and 4d, to the connecting element 14, which surrounds the web 40 and the spring arms 4a - 4d in a U-shape. In the middle of the mirror arrangement S of Fig. 3, from top to bottom, a cutting axis A is indicated, which divides the mirror arrangement symmetrically in its middle. Fig. 4 shows a schematic representation of an embodiment of a mirror arrangement S according to the invention in a side view according to the section axis A of Fig. 3 . Fig. 4 shows how the bridge 41 arranges the mirror in a second plane, which lies above the first plane of the spring arms 4a, 4b, 4c and 4d and the coil 20. Fig. 4 also shows the directions of movement 100a and 100b of the mirror 3, as well as the directions of movement 101a and 101b of the area 40 and directions of movement 102a, 102b and 103a, 103b of the coil 20. The directions of movement 100a and 100b of mirror 3 indicate a rotational movement around the center of mirror 3. Mirror 3 thus oscillates resonantly around its longitudinal axis. The directions of movement 101a and 101b indicate a linear movement of area 40 in the first plane. The directions of movement 102a and 102b indicate a linear movement of coil 20 in the first plane in the direction of mirror 3. Finally, the directions of movement 103a and 103b indicate a linear movement that points out of the first plane perpendicular to the directions of movement 102a and 102b. The following section will explain how the mirror arrangement S works. When the mirror oscillates in the direction of 100a, the lower part of the bridge 41, and thus the area 40, moves mainly linearly in the direction of 101a due to the distance of the mirror to the spring arms 4a to 4d. The coil 20 makes a compensating movement in the opposite direction 102a. Because the coil 20 is located far from the axis of rotation 100a, 100b, it essentially performs a linear movement 102a, 102b and only a small tilting movement 103a, 103b. The cavity 6, which is arranged in the coil former 2 in Fig. 4, serves to reduce the coil former mass, thereby increasing the movement amplitude of the coil former 2, which in turn increases the drive efficiency. The connecting bridges 45a and 45b also serve to increase the drive efficiency and facilitate the conversion of the rotary oscillating motion of the mirror 3 into the linear drive motion of the coil 20 or vice versa. Fig. 5 shows a schematic representation of an embodiment of a mirror arrangement S according to the invention in a top view. In contrast to Fig. 3, the second plane, in which the mirror 3 is located, lies above the first plane, in which the coil 20 and the spring arms 4a - 4d are located. Figure 5 shows that the mirror 3 is oval in shape. Further embodiments of the mirror 3 are possible in other configurations. In one embodiment, the coil former 2 can contain a cavity 6 to reduce the mass of the coil former. The cavity 6 can be designed as desired. The remaining cavity walls 16 serve for stabilization and can be ribbed in one embodiment, or, if stabilization is not necessary, omitted entirely. Fig. 6 shows a schematic representation of an embodiment of a mirror arrangement S according to the invention, which is based on the mirror arrangement of Fig. 5. In Fig. 6, the coil 20 has the cavity 6 on only three sides of the coil former 2. The side of the rectangular coil former 2 that is furthest from the mirror 3 does not have a cavity 6. By eliminating the cavity 6 at the end of the coil body 2, a balancing mass can be formed which reduces the tilting movement in the direction of movement 103a, 103b of the coil body 2. Fig. 7 shows a schematic representation of an embodiment of a mirror arrangement S according to the invention, which is based on the mirror arrangement of Fig. 3. The connecting element 14, which in Fig. 3 couples the spring arms 4a - 4d to the coil 20, has been omitted in Fig. 7. The spring arms 4a - 4d are guided directly from the area 40 to the coil body 2. In one variant, the spring arms 4a - 4d shown in Figure 7 can be replaced, for example, by a leaf spring. Fig. 8 shows a schematic representation of an embodiment of a mirror arrangement S according to the invention, which is based on the mirror arrangement of Fig. 3. In contrast to Fig. 3, no second springs 5 ​​are provided which meander from the coil body 2 or the ends of the connecting element 14 directly to the frame 1. Rather, the frame 1 in Fig. 8 has further spring elements 500, which are designed such that movement of the simply resonant system in the direction of movement 102a, 102b is hindered as little as possible. Furthermore, the spring elements block movement in the transverse direction to the direction of movement 102a, 102b. This is achieved through the special design of the spring elements 500, which are as soft as possible in the direction 102a, 102b and as stiff as possible in all other directions. Fig. 9 shows a schematic representation of an embodiment of a mirror arrangement S according to the invention, which is based on the mirror arrangement of Fig. 3. The mirror arrangement S shown in Figure 3 is provided in Figure 9 with a housing G, which consists of two caps 50, 51. Caps 50, 51 are designed such that the mirror 3 is hermetically sealed and, optionally, the housing has a low internal pressure relative to the ambient pressure, or a vacuum. The cap 50 is also laser beam transparent or has a window 50a, which is optionally also inclined to avoid reflection in the image beam path. Under the cap 50 is a plastic adhesive 52 with which the mirror arrangement S can be fixed to a substrate. The coil arrangement S of Fig. 9 also includes a magnet 200, which can, for example, also be attached with adhesive 53 to the side of the housing G facing away from the mirror 3. Adhesives 52 and 53, as well as the substrate, can exhibit high damping. However, with the soft springs 5 ​​shown (or springs 500 in Fig. 8), this damping is irrelevant, since the system is decoupled by the soft springs 5 ​​and the coil former 2 serves as a counterweight to the movement of the mirror 3 within the system itself. The drive of the simply resonant system is provided by the coil windings 7, which lie in a permanent magnetic field of the magnet 200. Furthermore, a flux guide plate 201 is arranged on the permanent magnet 200 of Fig. 9, so that the magnetic field lines of the magnetic field of the permanent magnet 200 run as perpendicularly as possible through the coil body 20 or the coil branches 7a, 7b. The magnetic field emerging from the pole of magnet 200 must be guided such that a force is generated in the direction designated 102a and 102b in Fig. 8. For this purpose, the field of the permanent magnet can be guided by means of the flux guide plate 201. This results in the magnetic field direction 70 shown in Fig. 9 in the region of the coil. In conjunction with the current field direction of the coil branches 7a and 7b, the force then results in the direction 102a and 102b. Coil branch 7a naturally has the opposite current direction to coil branch 7b. To set the mirror 3 into oscillation, the current field direction of the coil 20 is changed or controlled in pulses. Fig. 10 shows a schematic representation of an embodiment of a mirror arrangement S according to the invention, which is based on the mirror arrangement of Fig. 9. The mirror arrangement S of Fig. 10 does not have a flux guide plate 201. In this variant, it is primarily the coil branch 7b that generates the forces in the direction of movement 102a, 102b. Additionally, perpendicular movements of the outer coil branch (103a and 103b) can also be utilized. The field shape of Fig. 10 can also be realized with a flux guide plate. Fig. 11 shows a schematic representation of an embodiment of a mirror arrangement S according to the invention, seen from the side facing away from the mirror. The spring F is designed as a spiral spring 400 in Fig. 11. Due to the spiral spring 400, the coil body 2 moves in a different shape than in Fig. 3. If the mirror 3 oscillates in the direction 100a, 100b, the area 40 moves as before in the direction 101a, 101b. The end of the coil former 2 itself describes a movement at its end essentially perpendicular to the extent of the coil former 2, direction of movement 1002a and 1002b in Fig. 12, so that the rotational movement of the mirror 3 is compensated by a tilting movement of the coil 20. The different movement compared to Fig. 4 results from the low stiffness of the spiral spring in the direction 101a, 101b. The suspension must be achieved by secondary springs that are torsionally weak but as stiff as possible in all linear spatial directions. This is shown in Figs. 11 and 13. Here, the mirror 3 is connected to the outer frames 1 in the plane of the mirror itself by torsion springs 44a, and the coil 20 is connected to the outer frames 1 at its pivot point by springs 44b. Of course, the system can also be connected with any soft springs as shown in Figs. 3-5, but this increases its susceptibility to external vibrations. In Fig. 11, as in Fig. 3, a section line A is drawn in the middle of the mirror arrangement S. Fig. 12 shows a schematic representation of an embodiment of the mirror arrangement S according to the invention of Fig. 11 in a sectional view at the section line A. The movement in directions 1002a and 1002b is a movement of the rear part of the coil 20, furthest from the mirror 3, perpendicular to the first plane and can be used to drive the mirror 3, e.g., by a permanent magnet-generated field in direction 75 in combination with an alternating current in the coil branch 7a. A corresponding arrangement of the magnet 200 is shown in Fig. 14. The coil branch 7b remains ineffective in the direction of 1002a, 1002b, since the magnetic field only acts perpendicular to the direction 1002a, 1002b and is therefore ineffective for the resonant excitation of the system. It should also be noted that this system has a second pivot point with directions of rotation 110a, 110b. The second pivot point is located at the part of coil 20 closest to mirror 3. If the system of Fig. 11 and Fig. 12 is suspended at the pivot points 100a,b and 110a,b, i.e. coupled to the frame 1 by second springs 5, then excitability by external vibration is also minimized. In all embodiments of the mirror arrangement S, the current supply line to the coil 20 as well as signal lines, which e.g. sens the mirror deflection by means of the piezoresistive effect, can be routed via the soft springs 5 ​​or 500, or 44a and 44b. Sensing the magnitude of the oscillating mirror deflection can be achieved by means of a first measuring device M1 designed as piezoresistive resistors on the springs 4a to 4d or 400. First measuring devices M1, designed as piezoresistive resistors, can also be used on the soft springs 5, 500 and 44a, 44b for sensing the deflection of the oscillating mirror. These first measuring devices M1 are preferably arranged in the spring regions that are close to the coil former 2 or the connecting element 14. Additionally, second measuring devices M1, designed as piezoresistive resistors, can be integrated into the soft springs 5, 500, or 44a, 44b to measure the displacement of the softly suspended, single-resonant system. These second measuring devices are preferably located near the outer frame 1. With such measuring resistors, it is possible not only to use the magnet / coil system to excite the mirror 3 but also to actively influence the displacement of the softly suspended mirror / coil system. For example, in one embodiment, in addition to the higher-frequency oscillation of the oscillating mirror, the soft system can be excited at a low frequency. This allows the image quality, e.g., the spectral density of the image, to be influenced variably. The slight, low-frequency movement of mirror 3 reduces laser interference that can be disruptive during image viewing. Furthermore, the image despeppelization can be varied depending on the image content. For example, video sequences can be despeppelized differently than static images. Static images could also be despeppelized differently depending on whether they contain text or not. In one embodiment, an external excitation can be actively counteracted by a control system. For example, this ensures that impacts on or a sound source near the mirror 3 do not influence the vibration of the mirror 3 and thus the image quality. Fig. 13 shows a schematic representation of the embodiment of the mirror arrangement S according to the invention of Fig. 11 and Fig. 12 in a top view. Fig. 13 shows that the simply resonant system consisting of coil body 2 and mirror 3 is suspended once on the axis of oscillation of the mirror 3 via springs 44a and once at the end of the coil body 2 which is closest to the mirror 3 via springs 44b. Fig. 14 shows a schematic representation of an embodiment of a mirror arrangement S according to the invention. In the mirror arrangement S of Fig. 14, the magnet 200 and the flux guide plate 201 are arranged such that the end of the coil former 2 which has the coil branch 7a is transversely penetrated by the magnetic field of the magnet 200. This enables movement of this end of the coil former in the direction of movement 1002a and 1002b when current is energized to the coil branch 7a. Fig. 15 shows a schematic representation of an embodiment of a mirror 3 of a mirror arrangement S according to the invention. To prevent excessive deformation of the mirror 3 due to acceleration forces during dynamic oscillating mirror movement, it can be specially designed. Fig. 15 shows a rib structure that can be attached to the underside of the mirror 3. In Fig. 4 and Fig. 12, the ribs 601 partially replace the web 41, which also serves as a spacer to the first springs F or the spring arms 4a - 4d. The ribs extend outwards from the center of the mirror in a star shape. Fig. 16 shows a schematic cross-sectional view of mirror 3 of Fig. 15 . Figure 16 shows that only the bridge 41 determines the distance between the mirror and the first spring 5. The individual ribs 601 are shorter and are only made thick or deep enough to ensure the desired mechanical stability. Fig. 17 shows a schematic representation of a further embodiment of a mirror 3 of a mirror arrangement S according to the invention from below, i.e. the side of the mirror 3 facing away from the mirror surface. In Fig. 17, the rib structure is designed differently than in Figs. 15 and 16. The rib structure essentially features a central T-beam 602 that extends almost to the end of the mirror 3 and is parallel to the rotational axis of the mirror 3. This results in low rotational inertia and further stabilizes the mirror 3, as the height in the central region is now increased. Fig. 18 shows a schematic representation of the mirror 3 of Fig. 17 in a sectional view. The spacer 41 in Fig. 18 has a smaller height than in Fig. 16, since the mirror 3 moves only slightly in the central area, so that the overall height is comparable to that of the mirror 3 in Fig. 16. However, the mirror 3 in Fig. 18 is better stabilized against deformation. Since the T-beam 602 is also located near the axis of rotation, the rotational moment of inertia between the mirrors 3 of Fig. 16 and Fig. 18 changes only slightly. Since rib 602 is only located in the central area of ​​the axis of rotation, additional ribs 601 must be extended outwards to stabilize the outer parts of mirror 3. The number and design of the ribs 601 depend on the specific design. The optimal position and shape can be determined, for example, using calculation programs. Fig. 19 shows a schematic representation of an embodiment of a mirror arrangement S according to the invention. In Fig. 19, the mirror is positioned in the center of the coil 20, i.e., above the coil 20. Inside the square coil former 2, spring arms 4a-4d are located in the first plane, contacting the area 40 of the bridge 41 to connect the mirror 3 to the coil former 2. The coil former 2 is coupled to the frame 1 by two secondary springs 5. Fig. 20 shows a schematic representation of the embodiment of the mirror arrangement S according to the invention of Fig. 19 in a sectional view. In the embodiment of Fig. 19 and Fig. 20, the coil body 2 oscillates counter-rotatorily to the mirror 3, thus enabling the AVT coupling of the vibration energy to be avoided. The movement of mirror 3 is, as before, rotational in directions 100a, 100b, and the area 40 of the bridge 41 moves, as before, linearly in directions 101a, 101b. When the mirror moves in direction 100a, the coil former 2 oscillates in the opposite direction 1003a, 1004a. A slight movement of the coil former in directions 1010a, 1010b is possible. Fig. 21 shows a schematic representation of an embodiment of a mirror arrangement S according to the invention. The connecting element 14, which in Fig. 3 couples the spring arms 4a - 4d to the coil 20, has been omitted in Fig. 21. The spring arms 4a - 4d are guided directly from the area 40 to the coil body 2. In one variant, the spring arms 4a - 4d shown in Figure 21 can be replaced, for example, by a leaf spring. Fig. 22 shows a schematic representation of an embodiment of a mirror arrangement S according to the invention, which is based on the mirror arrangement S of Fig. 1. The mirror assembly S further comprises two second springs 5 ​​that connect the coil to the AVT. A first measuring device M1 is arranged on the first coil F, which detects the movement of the mirror Sp. Furthermore, a second measuring device M2 is attached to one of the second coils 5, which detects the strain or movement of the second coil and thus the movement of the singly resonant system consisting of coil Su, spring F, and mirror Sp. The first and second measuring devices M1, M2 are coupled to a control unit ST, which controls coil Su based on the measured values ​​of the first and second measuring devices M1, M2.

Claims

Mirror arrangement (S), comprising a mirror (Sp, 3) which is mounted for vibration; comprising a coil (Su, 20); comprising at least one first spring (F) which couples the mirror (Sp, 3) and the coil (Su, 20) to each other in such a way that the coil (Su, 20) is arranged as a counterweight to the vibrating mirror (Sp, 3); comprising a frame (1); comprising at least one second spring (5), in particular a spring which is flexible or soft in at least one direction and which couples the frame (1) to the mirror (Sp, 3) and / or the coil (Su, 20) and / or the at least one first spring (F); comprising at least one second measuring device (M2), in particular at least one piezoresistive resistor which is configured to detect the deflection of the group consisting of the mirror (Sp, 3) and / or the coil (Su, 20) and / or the at least one first spring (F), and which is in particular arranged on the at least one second spring (5). Mirror arrangement according to claim 1, characterized in that the mirror (Sp, 3) is designed to oscillate rotationally; and the at least one first spring (F) couples the mirror (Sp, 3) and the coil (Su, 20) such that the coil (Su, 20) oscillates in the opposite direction of movement of the mirror (Sp, 3). Mirror arrangement according to one of the preceding claims, characterized in that the coil (Su, 20) has a coil body (2), in particular a coil body (2) with a cavity (6), and a coil winding (7) which is arranged on the coil body (2). Mirror arrangement according to one of the preceding claims, characterized in that the at least one first spring (F) and the coil (Su, 20) are arranged in a first plane and the mirror (Sp, 3) is arranged above the first plane in a second plane which is parallel to the first plane, wherein the mirror (Sp, 3) is coupled to the at least one first spring (F) in particular via a bridge (41) of a predetermined length. Mirror arrangement according to claim 4, characterized in that the at least one first spring (F) has four spring arms (4a, 4b, 4c, 4d) which are meander-shaped and which are coupled at one end to the bridge (41), or that the at least one first spring (F) has two spring arms (4a, 4b, 4c, 4d) which are circular and which are coupled at one end to the bridge (41), wherein the spring arms (4a, 4b, 4c, 4d) are coupled at their other end to a connecting element (14) which couples the at least one first spring (F) to the coil (Su, 20), or wherein the spring arms (4a, 4b, 4c, 4d) are directly coupled at their other end to the coil (Su, 20). Mirror arrangement according to one of the preceding claims, comprising a housing (G) which encloses at least the mirror (Sp, 3) and the coil (Su, 20) and the at least one first spring (F), wherein the housing (G) in particular has a lower air pressure, in particular a vacuum, than the environment of the housing (G) and is hermetically sealed. Mirror arrangement according to claim 6, characterized in that the housing (G) above the mirror (Sp, 3) is at least partially transparent to laser beams or has a window above the mirror (Sp, 3), in particular a window inclined relative to the first plane or the second plane, which is transparent to laser beams, Mirror arrangement according to one of claims 6 or 7, with a magnet (200), in particular a permanent magnet (200), which is arranged on the housing (G) such that the coil (Su, 20) lies in the magnetic field of the magnet (200). Mirror arrangement according to claim 8, with a flux guide plate (201) which is arranged on the magnet (200) such that the magnetic field of the magnet (200) penetrates the first plane in the region of the coil (Su, 20) approximately perpendicularly or approximately horizontally. Mirror arrangement according to one of the preceding claims, comprising at least one first measuring device (M1), in particular at least one piezoresistive resistor, which is configured to detect the mirror deflection of the mirror (Sp, 3), and which is in particular arranged on the at least one first spring (F). Mirror arrangement according to claim 1, with a control device (ST) which is configured to control the coil (Su, 20) based on the measured values ​​of the at least one first measuring device (M1) and / or the at least one second measuring device (M2) in such a way that the group consisting of the mirror (Sp, 3) and / or the coil (Su, 20) and / or the at least one first spring (F) is excited at a predetermined frequency, or to control the coil (Su, 20) in such a way that externally occurring excitations are actively counteracted. Mirror arrangement according to one of the preceding claims, characterized in that the mirror (Sp, 3) has a base plate on the upper side of which the mirror surface is arranged and on the lower side of which a stiffening element (601) is arranged which is designed to mechanically stabilize the mirror (Sp, 3). Projection device comprising a light source (L); comprising at least one mirror arrangement (S) according to one of claims 1 to 12; and comprising a control (SE) for controlling the at least one mirror arrangement (S).

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