Abstract
A microelectromechanical device for generating a fluid pressure using a displacer unit. The displacer unit has a movable displacer element, which can be deflected to generate a fluid pressure using a drivable connecting element acting on the displacer element. The connecting element has a base structure and a coupling structure connected to the base structure for connecting the connecting element to the displacer element. The base structure includes a mass reduction portion with a material recess. A microelectromechanical loudspeaker having such a microelectromechanical device is also described.
Claims
1. A microelectromechanical device for generating a fluid pressure, comprising: a displacer unit including a movable displacer element which can be deflected to generate the fluid pressure using a drivable connecting element acting on the displacer element; wherein the connecting element has a base structure and a coupling structure connected to the base structure for connecting the connecting element to the displacer element, and wherein the base structure includes a mass reduction portion with a material recess.
2. The device according to claim 1, wherein the material recess is formed as a cavity region which occupies a partial volume of at least 5% of a total volume of the base structure.
3. The device according to claim 2, wherein the coupling structure is a coupling rib extending through the cavity region.
4. The device according to claim 1, wherein the coupling structure has a material reinforcement in portions.
5. The device according to claim 1, wherein the base structure has at least one wall structure with a predominantly closed wall surface.
6. The device according to claim 1, wherein the base structure has at least one etching channel for producing the material recess.
7. The device according to claim 1, wherein the material recess is a micropore which occupies a partial volume of at most 20% of a total volume of the base structure.
8. The device according to claim 1, wherein the mass reduction portion has at least two spatially separated material recesses.
9. The device according to claim 1, wherein the connecting element has a spring structure which is arranged at least in portions in a material recess of the base structure.
10. The device according to claim 1, wherein the connecting element has a spring structure which is formed integrally with the base structure.
11. The device according to claim 1, wherein the device has a drive apparatus which is arranged at least in portions in a material recess of the base structure of the connecting element.
12. The device according to claim 11, wherein the drive apparatus has at least one fixed drive element and at least one movable drive element.
13. A microelectromechanical loudspeaker, comprising: a microelectromechanical device for generating a fluid pressure, including: a displacer unit including a movable displacer element which can be deflected to generate the fluid pressure using a drivable connecting element acting on the displacer element, wherein the connecting element has a base structure and a coupling structure connected to the base structure for connecting the connecting element to the displacer element, and wherein the base structure includes a mass reduction portion with a material recess, wherein the displacer unit is configured to generate sound pressure as the fluid pressure; and a signal processing unit configured to apply and process signals from the microelectromechanical device.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0037] FIG. 1 shows a schematic basic principle of a microelectromechanical device, according to an example embodiment of the present invention.
[0038] FIGS. 2A-2B show a bottom view and a lateral cross-sectional view of a connecting element of the device according to a first example embodiment of the present invention.
[0039] FIGS. 3A-3B show a bottom view and a lateral cross-sectional view of a connecting element of the device according to a second embodiment example embodiment of the present invention.
[0040] FIGS. 4A-4C show a bottom view and two lateral cross-sectional views of a connecting element of the device according to a third example embodiment of the present invention in two variants.
[0041] FIGS. 5A-5C show a bottom view and two lateral cross-sectional views of a connecting element of the device according to a fourth example embodiment of the present invention in two variants.
[0042] FIGS. 6A-6B show a bottom view and a lateral cross-sectional view of a connecting element of the device according to a fifth example embodiment of the present invention.
[0043] FIGS. 7A-7C show a bottom view, a detailed view of the bottom view and a lateral cross-sectional view of a connecting element of the device according to a sixth example embodiment of the present invention.
[0044] FIGS. 8A-8B show a bottom view and a lateral cross-sectional view of a connecting element of the device according to a seventh example embodiment of the present invention.
[0045] FIG. 9 shows a schematic diagram of a microelectromechanical loudspeaker having a microelectromechanical device, according to an example embodiment of the present invention.
DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS
[0046] FIG. 1 schematically shows a device 1 for generating a fluid pressure using a displacer unit 2. According to the exemplary embodiment, the displacer unit 2 has two movable displacer elements 3, which can be deflected to generate a fluid pressure by means of a drivable connecting element 5 acting on the displacer elements 3. As shown, the displacer elements 3 are designed as flat, deflectable structures with a vertical orientation in the displacer unit 2. The connecting element 5 is connected to an outer edge of the displacer elements 3 via a coupling structure 7 and is movable in opposite drive directions A perpendicular to the displacer elements 3 by means of a drive apparatus 8, to which the connecting element 5 is connected via drive coupling elements 9, in order to be able to deflect the displacer elements 3 simultaneously. The movable displacer elements 3, together with a fixed counter element 4, the connecting element 5 and a bottom surface (not shown in detail) opposite the connecting element 5, each define a displacer volume V which can be changed by deflection of the adjacent displacer element 3 in order to generate a fluid pressure.
[0047] The connecting element 5 has a base structure 6 and the coupling structures 7 connected to the base structure 6 for connecting the connecting element 5 to the displacer elements 3. The base structure 6 is represented in the shown exemplary embodiments with a cuboid basic shape, but it can in principle also have other basic geometric shapes. The coupling structures 7 have a smaller overall size than the base structure 6. Opposing spring structures 10 are connected to the base structure 6 and enable a return and/or oscillating movement of the connecting element 5.
[0048] In FIGS. 2A and 2B, a bottom view and a lateral cross-sectional view of a connecting element 5 of the device 1 according to a first embodiment are shown, wherein the lateral cross-sectional view in FIG. 2B is shown along the section line A-A illustrated in FIG. 2A. For the sake of simplicity, the drive apparatus 8, the displacer elements 3 and the fixed counter element 4 are hidden in FIGS. 2A and 2B as well as in some subsequent figures.
[0049] From FIGS. 2A and 2B, it can be seen that the base structure 6 of the connecting element 5 has a mass reduction portion 11. The mass reduction portion 11 has material recesses 12, which are formed as a first cavity region 12-1a, a second cavity region 12-1b and a third cavity region 12-1c, as shown. Weight savings on the connecting element 5 can therefore be achieved. The cavity regions 12-1a, 12-1b and 12-1c are spatially separated from one another by coupling structures 7 designed as coupling ribs, or in other words, the coupling ribs extend through a cavity region 12-1 formed by the cavity regions 12-1a, 12-1b and 12-1c.
[0050] The base structure 6 substantially has a box shape with four side walls 15a, a cover wall 15b and an open side toward the displacer element 3. In lateral cross section, the aforementioned wall structures 15 form a U shape. The wall structures 15 form outer walls of the base structure 6 and each have a predominantly closed wall surface and thus a high rigidity. The plate-shaped coupling structures 7 each have a width be that is smaller than 20% of the width bi of the base structure 6. The coupling structures 7 are connected to the cover wall 15b and to two opposite side walls 15a. The coupling structures 7 can be connected to displacer elements 3 on an underside of the coupling structures 7 facing away from the cover wall 15b. The side walls 15a, the cover wall 15b and the coupling structures 7 delimit the cavity regions 12-1a, 12-1b and 12-1c. Each cavity region 12-1a, 12-1b and 12-1c forms a contiguous cavity volume which occupies a partial volume of the base structure 6 that is greater than 5% of the total volume of the base structure 6. The spring structures 10 are connected to two opposite side walls 15a of the base structure 6.
[0051] In FIGS. 3A and 3B, a bottom view and a lateral cross-sectional view of a connecting element 5 of the device 1 according to a second embodiment are shown, wherein the lateral cross-sectional view in FIG. 3B is shown along the section line A-A illustrated in FIG. 3A. In its base structure, the connecting element 5 according to the second embodiment is comparable with the connecting element 5 according to the first embodiment. The second embodiment represents a variant of the base structure 6 optimized according to lightweight construction criteria with a topology-optimized mass distribution. In this case, a higher mass concentration is provided in regions of higher load along the force paths from the drive apparatus 8 to the displacer element 3 than in regions of lower load. The base structure 6 has a mass reduction portion 11 with material recesses 12, which are formed as a first cavity region 12-1a, a second cavity region 12-1b and a third cavity region 12-1c, as shown. The coupling structures 7 are basically designed as coupling ribs in a similar manner to the first embodiment, but each have a material reinforcement 13 in the form of a conical cross-sectional widening on a subportion facing the drive apparatus 8 or the drive coupling elements 9. In addition, a wall structure 15 designed as a cover wall 15b has a wall structure reinforcement 16 in portions in order to provide local stiffening.
[0052] In FIGS. 4A, 4B and 4C, a bottom view of a connecting element 5 of the device 1 according to a third embodiment and two variants of the third embodiment are shown in lateral cross-sectional views, wherein the lateral cross-sectional views in FIGS. 4B and 4C are shown along the section line A-A illustrated in FIG. 4A. In its base structure, the connecting element 5 according to the third embodiment is comparable with the connecting element 5 according to the first embodiment. However, the connecting element 5 according to the third embodiment has on the base structure 6, in addition to the side walls 15a and the cover wall 15b, a bottom wall 15c which, with the other aforementioned wall structures 15, delimits a continuous cavity region 12-1 according to FIG. 4B or, with the aforementioned wall structures 15 and additional inner partition walls, delimits a plurality of spatially separated cavity regions 12-1a, 12-1b, 12-1c and 12-1d according to FIG. 4C. As a result, the mass of the base structure 6 can be reduced and the rigidity can be increased by the wall structures 15. Etching channels 14, which are spaced apart from one another, lead through the bottom wall 15c and enable the production of the cavity regions 12-1 or 12-1a, 12-1b, 12-1c and 12-1d by means of an etching process. In this exemplary embodiment, the coupling structures 7 are integrally formed on the bottom wall 15c.
[0053] In FIGS. 5A, 5B and 5C, a bottom view of a connecting element 5 of the device 1 according to a fourth embodiment and two variants of the fourth embodiment are shown in lateral cross-sectional views, wherein the lateral cross-sectional views in FIGS. 5B and 5C are shown along the section line A-A illustrated in FIG. 5A. In the fourth embodiment, the base structure 6 of the connecting element 5 has a plurality of micropores 12-2 which form material recesses 12 in a mass reduction portion 11 of the base structure 6. The micropores 12-2 each occupy a partial volume of the base structure 6 that is less than 20% of the total volume of the base structure 6. As a result, the rigidity of the connecting element 5 can be improved and a high fluid tightness can be achieved. According to the variant in FIG. 5B, the mass reduction portion 11 is designed as a foam structure having a plurality of enclosed micro-cavities 12-2b. According to the variant in FIG. 5C, the mass reduction portion 11 has a plurality of spaced-apart through-channels 12-2a.
[0054] In FIGS. 6A and 6B, a bottom view and a lateral cross-sectional view of a connecting element 5 of the device 1 according to a fifth embodiment are shown, wherein the lateral cross-sectional view in FIG. 6B is shown along the section line A-A illustrated in FIG. 6A. In its base structure, the connecting element 5 according to the fifth embodiment is comparable with the connecting element 5 according to the third embodiment. In the fifth embodiment, the base structure 6, as shown, has laterally open cavity regions 12-1a and 12-1c into which the spring structures 10 of the connecting element 5 dip in portions. This makes it possible to provide a compact connecting element 5 with an integrated functional component.
[0055] In FIGS. 7A, 7B and 7C, a bottom view, a detailed view and a lateral cross-sectional view of a connecting element 5 of the device 1 according to a sixth embodiment are shown, wherein the lateral cross-sectional view in FIG. 7C is shown along the section line A-A illustrated in FIG. 7A. In its base structure, the connecting element 5 according to the sixth embodiment is comparable with the connecting element 5 according to the first embodiment. According to the sixth embodiment, the drive apparatus 8 of the device 1 is arranged in a material recess 12, here in cavity regions 12-1a, 12-1b and 12-1c. As a result, the drive apparatus 8 can be arranged in the device 1 in a space-saving manner and efficiently integrated into the connecting element 5. The drive apparatus 8 has fixed drive elements 8a and movable drive elements 8b, which are movable relative to one another, for example by an electrical signal, and can entrain the connecting element 5 with them. As shown in FIG. 7B, the fixed drive elements 8a and the movable drive elements 8b can be designed as comb electrode bars with comb electrode fingers 8c in order to enable a uniform and precisely controllable drive movement.
[0056] In FIGS. 8A and 8B, a bottom view and a lateral cross-sectional view of a connecting element 5 of the device 1 according to a seventh embodiment are shown, wherein the lateral cross-sectional view in FIG. 8B is shown along the section line A-A illustrated in FIG. 8A. In its base structure, the connecting element 5 according to the seventh embodiment is comparable with the connecting element 5 according to the sixth embodiment. According to the seventh embodiment, the base structure 6 in the mass reduction portion 11 has a continuous cavity region 12-1 as a material recess 12, in which the drive apparatus 8 is arranged. The drive apparatus 8 is protected in a sandwich-like manner between a bottom wall 15c and a cover wall 15b. The coupling structures 7 are integrally formed on the bottom wall 15c.
[0057] FIG. 9 schematically shows a microelectromechanical loudspeaker 17 having a device 1 according to the above-described features and a signal processing unit 18 which is connected to the device 1 by a signal connection 19 and is designed to apply and process signals from the microelectromechanical device 1. The displacer unit 2 of the device 1 is configured to generate sound pressure as fluid pressure. By reducing the mass of the base structure 6 of the connecting element 5 of the device 1, a higher efficiency of the loudspeaker 17 can be achieved, among other things. The microelectromechanical loudspeaker 17 can be, for example, implemented as a system-on-chip.
