Microelectromechanical coupling device

Abstract

A microelectromechanical coupling device (100) for coupling microelectromechanical components according to the present invention has a flexible ring structure (110) that forms a circle in a stationary state and is deformable substantially parallel to the plane of the circle, and is suitable for coupling microelectromechanical components (200), and a plurality of spring elements (120) suitable for connecting the ring structure (110) to a substrate. The coupling device (100) has a large number of spring elements (120), and the width of the ring structure (110) in the circumferential direction is small and the spring hardness is low, so the deformability of the ring structure (110) is homogeneous in the circumferential direction of the ring structure (110).

Description

Technical Field

[0001] The present invention relates to a microelectromechanical coupling device for coupling microelectromechanical components, a microelectromechanical measuring device, and particularly an annular microelectromechanical angular velocity sensor including the coupling device.

Background Art

[0002] In micro-mechanical measuring devices such as angular velocity sensors and acceleration sensors, different micro-mechanical components such as oscillation systems or masses often have to be connected to each other in order to couple their respective movements.

[0003] A non-mounted ring that is coupled by free-floating is often desirable in this case. This is because such a ring reacts with a deflection having the same amplitude regardless of the point in the circumferential direction to which the action of the radial force is applied with respect to the action of the radial force. Similarly, it is also advantageous to use a free-floating ring as an angular velocity sensor, in which case the excitation vibration is superimposed on the detected vibration due to the Coriolis force during rotation.

Summary of the Invention

[0004] However, the problem here is that the translational mode forms the first natural mode without connecting to the substrate of the measuring device. However, these are often not desirable. Furthermore, the manufacture of non-mounted rings for coupling microelectromechanical components requires a great deal of labor in terms of manufacturing technology.

[0005] A well-known example of this is the use of highly rigid and short connections (so-called spokes). This is very space-saving, but due to its high rigidity, resonance in the range of several kHz is not allowed. Furthermore, in this design, a homogeneous behavior in the circumferential direction cannot be obtained.

[0006] Alternatively, a spring that is very long and thus space-consuming, but also very flexible, is used. In this case, although the resonance frequency is lowered, since a circumferentially uniform behavior cannot be obtained, the deviation from an ideal ring is also very large.

[0007] Therefore, the aim is to achieve an attachment to the ring structure that is as homogeneous as possible so as to have as little influence as possible on the perfect symmetry of the ring structure. This could be achieved by completely omitting the attachment part, but it is very difficult to implement. Also, when using a number of springs distributed circumferentially, the stiffness of the springs must not be too high. This is because if the stiffness of the springs is too high, it will have too much of a local influence on the ring and the natural vibration frequency of the entire system will increase. Therefore, there is a contradictory aim of providing a coupling that is as flexible as possible and at the same time does not require much installation space.

[0008] Thus, the present invention aims to identify a microelectromechanical coupling device and an annular microelectromechanical angular velocity sensor that achieve the above advantages of a free-floating non-attached ring without causing the above-mentioned drawbacks.

[0009] This object is achieved by the subject matter according to claim 1.

[0010] A microelectromechanical coupling device for coupling microelectromechanical components has a flexible ring structure that forms a circle in a stationary state, can deform substantially parallel to the plane of the circle, and is suitable for coupling microelectromechanical components. Further, the coupling device includes a plurality of spring elements suitable for connecting the ring structure to a substrate, and the coupling device includes a large number of spring elements having a small width in the circumferential direction of the ring structure and a low spring hardness so that the deformability in the circumferential direction of the ring structure is homogeneous.

[0011] Therefore, the coupling device has a ring as its basic structure. This ring is mounted above the substrate and has, for example, the shape of a self - contained rod whose height perpendicular to the substrate is several times its width parallel to the substrate. In the stationary state, this ring forms a circle in the broadest sense, i.e., a closed curve parallel to the substrate. The deformation of the ring is only possible substantially in a direction parallel to the substrate, i.e., the deformation perpendicular to the substrate is operationally negligible.

[0012] To suppress the translational mode, the ring structure is connected to the substrate via a number of spring elements. Here, the connection to the substrate does not have to be direct, i.e., additional elements can also be interposed between the substrate and the spring elements. The number of spring elements ensures that the ring structure is coupled to the substrate at many points along the circumferential direction. For this purpose, the spring elements are designed to be sufficiently narrow in the circumferential direction of the ring structure so that their respective movements do not interfere with each other. Finally, the spring stiffness of each spring element must also be sufficiently low so as not to overly limit the desired free deformability of the ring structure.

[0013] The parameters of the number of spring elements, the width in the circumferential direction, and the spring stiffness are interdependent. For example, when using very soft spring elements, the number of spring elements can be reduced and their width can be increased. When using stiffer spring elements, the number can be increased or the width can be decreased.

[0014] Therefore, there are numerous possibilities for specifying the parameters of the spring element. However, the only decisive factor here is that the selected parameters only limit the deformability of the ring structure to the extent that the ring structure retains homogeneous spring characteristics in the circumferential direction. Thus, the ring structure must be coupled to the substrate by the spring element such that, in response to the action of a radial force, it deflects with the same amplitude / deformation (first approximation) regardless of at which point in the circumferential direction the radial force is applied. Therefore, the overall system of the spring element and the ring structure, when excited externally, and particularly when excited by the coupled microelectromechanical components, must respond (in a first approximation) like a translationally fixed but otherwise free-floating ring. For this reason, the overall system of the ring structure and the spring element appears, when viewed externally, like a free-floating ring with a spring stiffness that correlates to the ring structure.

[0015] This enables the realization of a coupling device that appears like a free-floating ring from the outside but whose translational mode is suppressed by reconnection to the substrate. Furthermore, due to the large number of spring elements, a sufficiently flexible coupling is possible, and excitation modes in the kHz band can also be realized. This excitation mode in the kHz band is particularly interesting for microelectromechanical measuring devices, especially ring-shaped angular velocity sensors.

[0016] The term coupling device should be understood broadly here and is meant to include the coupling or connection of various microelectromechanical components such as masses, springs, vibration systems, or electrodes. In particular, the coupling device can be the vibration system of a ring-shaped angular velocity sensor. And the microelectromechanical components are coupled to the ring structure to generate or measure the excitation or detection vibrations of the ring structure. However, in this case, the microelectromechanical components can also simply be connected to the substrate, like the spring element.

[0017] The ratio of the effective overall stiffness of the spring elements during the operation of the coupling device in the vibration mode to the product of the number of spring elements and the effective stiffness of the ring structure in the corresponding vibration mode can preferably be 1 or less. The effective stiffness of the spring element, in this case, indicates how the spring element as a whole reacts to the bending / vibration of the ring, and thus takes into account the fact that different springs bend differently during vibration, particularly in different directions, and thus each contributes with its own different spring stiffness. The same applies to the spring stiffness of the ring structure, and therefore the spring stiffness of the ring structure is also taken into account in the comparison as the effective stiffness, i.e., the stiffness that can actually be measured in a specific case. For example, if there are 20 springs and the effective stiffness of the ring structure is about 15 N / m, the upper limit of the effective stiffness of all the springs in the corresponding vibration mode is 300 N / m. If there are 40 springs and the effective stiffness of the ring structure is about 30 N / m, the upper limit of the effective combined stiffness of all the springs is 1200 N / m.

[0018] All the spring elements can be connected either inside or outside the ring structure. Thus, the coupling of the ring structure can be flexibly guided either inside or outside the ring structure according to the use of the ring structure. When all the spring elements act only on one side of the ring structure, a force- and torque-free coupling of the microelectromechanical components through the ring structure becomes possible.

[0019] The spring element can be designed as a serpentine spring. That is, the spring element is composed of a plurality of bent beam springs that extend along the circumferential direction of the ring structure so that a serpentine shape or a zigzag line is formed, and are alternately connected to each other at their ends. Such a spring can be designed compactly both in the circumferential direction and in the radial direction, and yet has a low spring hardness and can bring the resonance frequency of the coupling device into the kHz range. Therefore, it is particularly suitable for coupling the ring structure to the substrate. The serpentine spring can have 5 to 50 bent beam springs in the circumferential direction, for example, 10, 20, or 30.

[0020] The spring elements can be evenly arranged along the circumferential direction of the ring structure. As a result, all the spring elements can be designed in the same way to have a homogeneous deformability of the ring structure, that is, the same spring hardness, which facilitates manufacturing.

[0021] The number of spring elements can be 4, 8, 16, or 30 or more, preferably 40 or more, and more preferably 50 or more. Thereby, the density of the spring elements along the circumferential direction becomes sufficiently high. Thereby, the homogeneity of the deformability of the ring structure is improved.

[0022] The circumferential width of the spring element can be 1 / 4 or less, 1 / 8 or less, 1 / 16 or less, or 1 / 30 or less of the circumference of the ring structure, preferably 1 / 40 or less, and more preferably 1 / 50 or less. The spring element is narrow enough to be coupled to the ring structure at a number of positions along the circumferential direction of the ring structure.

[0023] The spring element can extend along the radial direction of the ring structure over less than 1 / 2 or less than 1 / 4, preferably less than 1 / 5, and more preferably less than 1 / 8 of the radius of the ring structure in the stationary state. Thereby, the spring element also takes up little space in the radial direction, so that the coupling device can be designed compactly.

[0024] The coupling device can further include a second ring structure. The plurality of spring elements are connected to the ring structure and the second ring structure. The ring structure is connected to the substrate via the second ring structure. The second ring structure is then preferably connected to the substrate by additional spring elements. Therefore, the spring elements couple the two ring structures together. Thereafter, similar spring elements can be further coupled to the second ring structure. However, other microelectromechanical components and spring elements can also be used to connect the second ring structure to the substrate. It is also conceivable to alternately arrange a plurality of ring structures connected by flexible spring elements. Thereby, the flexibility in the design of the coupling device and in the design of any measuring device including the coupling device is improved.

[0025] The microelectromechanical measurement device includes the microelectromechanical coupling device as described above and the microelectromechanical component connected to the coupling device. Thereby, the advantages achievable by the coupling device can be utilized in the microelectromechanical measurement device.

[0026] The annular microelectromechanical angular velocity sensor includes the microelectromechanical coupling device as described above. The ring structure is suitable for generating an excitation vibration, and the excitation vibration is superimposed on the detection vibration generated by the Coriolis force during the rotation of the ring structure. At this time, the spring element can constitute the microelectromechanical component.

Brief Description of the Drawings

[0027] Hereinafter, the present invention will be further described with reference to the drawings. The drawings and their descriptions are purely illustrative. The present invention is defined only by the subject matter of the claims.

Figure 1A

Figure 1B

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0028] Figures 1A and 1B respectively show schematic diagrams of the microelectromechanical coupling device 100. The microelectromechanical coupling device 100 is suitable for coupling the microelectromechanical component 200 such as used in a microelectromechanical measurement device such as an angular velocity sensor and / or an acceleration sensor. The microelectromechanical coupling device 100 can also form the basic structure of an annular angular velocity sensor. Figure 1B is a cross-section through Figure 1A along line l-l.

[0029] The coupling device 100 has a flexible ring structure 110 and a plurality of spring elements 120. As depicted in FIG. 1A, the ring structure forms a circle in the stationary state and is deformable substantially parallel to the plane of the circle. As seen in FIG. 1B, the substantially rectangular cross-section of the ring structure 110 is perpendicular to the plane of the circle, i.e., perpendicular to the substrate 300 to which the ring structure 110 is attached, and the long side perpendicular to the substrate 300 is many times longer than the short side parallel to the substrate 300. Thus, the ring structure 110 can be regarded as a self-contained bending beam spring that can deform, for example, parallel to the substrate 300, and deformation perpendicular to the substrate 300 can be ignored (in a first approximation). The shape of the depicted ring structure 110 is purely exemplary. The ring structure 110 can have any shape that preferably allows only deformation substantially parallel to the substrate plane. The ring structure 110 can also have a degenerate circular shape in the stationary position and can be designed, for example, as an ellipse or a rounded polygon. Thus, such a degenerate circular shape is also meant to be covered by the reference to the circular ring structure 110.

[0030] The coupling point 112 is shown on the ring structure 110 where the microelectromechanical components 200 to be coupled act or where these components 200 are connected to the ring structure 110. Through the coupling, the movement between the microelectromechanical components 200 can be transmitted or adjusted. In particular, the coupling device can mediate a push-pull vibration without force and torque between the components 200. The microelectromechanical components 200 can be, for example, a sensor mass or a vibration system. However, in principle, the type, structure, and size of the components 200 to be coupled are arbitrary. Also, the number of components 200 can be two or more.

[0031] It can also be coupled via the spring element 120. In that case, the coupling point 112 disappears. In particular, when the coupling device 100 is part of an annular microelectromechanical angular velocity sensor, the spring element 120 can constitute the microelectromechanical components. The ring structure is suitable for generating an excitation vibration, which is superimposed on the detection vibration generated by the Coriolis force during the rotation of the ring structure.

[0032] The ring structure is connected to the substrate 300 via a plurality of spring elements 120. The spring elements 120 act on various points of the ring structure 110 and hold the ring structure above the substrate 300. As depicted in FIGS. 1A and 1B, the spring elements 120 can be connected to the anchor structure 125, and in that way, the ring structure 110 can be directly connected to the substrate 300. The anchor structure 125 can have any shape as long as it enables a fixed connection to the substrate 300.

[0033] The coupling device 100 has a sufficient number of spring elements 120 such that the deformability in the circumferential direction of the ring structure 110 is homogeneous, the width in the circumferential direction of the ring structure 110 is thus small, and the spring hardness is thus low, so that the coupling device 100 has a resonance frequency in the kHz range. In particular, the width and number of the spring elements 120 can be arranged so that the spring elements 120 are as close to each other as possible without restricting the desired mobility of the spring elements 120. On the other hand, when the spring hardness of the spring elements 120 is sufficiently low, it is also fully possible to increase the distance between the spring elements 120 or widen the width of the spring elements 120 in order to obtain a homogeneous deformability of the ring structure.

[0034] For example, the number of the spring elements 120 can be 4 or more, 8 or more, 16 or more, 30 or more, 40 or more, or 50 or more. Corresponding to or independently of the number of the spring elements, the width of the spring elements 120 can be 1 / 4 or less, 1 / 8 or less, 1 / 16 or less, 1 / 30 or less, 1 / 40 or less, or 1 / 50 or less of the circumference of the ring structure 110.

[0035] The large number of acting points of the spring element 120 on the ring structure 110 ensures that the response of the ring structure 110 to the influence of the force is substantially the same circumferentially, similar to the spring stiffness resulting from the spring stiffness of the ring structure 110 and the spring element 120 that deform due to the influence of the force, and similar to the total spring stiffness. Therefore, the coupling device 100 reacts in the same way to the influence of the force from any direction, that is, it has a homogeneous deformability. Thus, the entire coupling device 100 is fixed translationally but otherwise reacts to external stimuli like a free-floating ring.

[0036] As depicted in FIG. 1A, all the spring elements 120 can be connected to the inside of the ring structure 110. However, the spring elements 120 can also be connected to the outside of the ring structure 110, for example, as depicted in FIGS. 4 and 5. By arranging all the spring elements 120 on the outside or inside of the ring structure 110, it can be ensured that the microelectromechanical component 200 can be coupled without being subjected to force or torque (by appropriately selecting the position of the connection point 112). However, in principle, the spring elements 120 can also act from both sides of the ring structure 110.

[0037] As depicted in FIGS. 3 to 5, the spring elements 120 can be evenly arranged along the circumferential direction of the ring structure 110. This allows all the spring elements 120 to be manufactured in the same way, simplifying the production of the coupling device 100. As a result, the equal spring stiffness of the spring elements 120, combined with the even distribution along the circumferential direction of the ring structure 110, ensures that the action of the force on the coupling device 100 generates the same reaction force at all points of the coupling device 100.

[0038] As depicted in FIG. 1A, the spring elements 120 can also be distributed non-uniformly along the circumferential direction of the ring structure 110. In this case, the spring stiffness of the various spring elements 120 must vary such that, nevertheless, a homogeneous deformability of the ring structure 110 can be achieved as a result. For example, the spring elements 120 can have a lower spring stiffness in regions where the density of the spring elements 120 is high than in regions where the density of the spring elements 120 is low.

[0039] In addition to restricting the width of the spring elements 120 along the circumferential direction, it is also desirable to limit the length of the spring elements 120 along the radial direction of the ring structure 110 to less than 1 / 2, 1 / 4, 1 / 5, 1 / 6, 1 / 8 or 1 / 10 of the radius of the ring structure 110 at rest. As a result, for example, as depicted in FIG. 5, the internal space of the coupling device 100 can also be used for the placement of the microelectromechanical components 200, so that a more compact microelectromechanical structure can be realized.

[0040] The spring elements 120 are depicted completely schematically by spiral spring symbols in FIGS. 1A and 1B. However, the spring elements 120 can have any shape as long as a sufficiently low spring stiffness can be achieved.

[0041] It has been proven that it is particularly advantageous to design the spring element 120 as, for example, a serpentine spring. An example of a serpentine spring is schematically depicted in FIG. 2. This bellows spring has, for example, a plurality of transverse springs 122 formed by bending beam springs whose main deflection direction is parallel to the substrate 300. The transverse springs 122 have their both ends alternately connected to the spring bars 124, forming a bellows-shaped spring. The spring bars 124 can also be significantly shortened or omitted so that a zigzag line is basically formed. FIG. 2 only shows the basic structure. The individual elements of the bellows spring can also have different designs. For example, the transverse springs 122 can also be designed as a series of arcs, particularly concentric circles. Also, the spring bars 124, or generally the connections between the transverse springs 124, do not have to be arranged in a straight line and can also be offset with respect to each other. The serpentine spring is basically a multi-bending or torsion bending beam spring with a serpentine shape.

[0042] Due to this structure, the serpentine spring is soft with respect to deflection in the plane in which it snakes (the image plane of FIG. 2), but relatively stiff with respect to deflection perpendicular to the plane in which it snakes (perpendicular to the image plane of FIG. 2). That is, with the minimum length of the spring bars 124 required to connect the transverse springs 122, if the length of the transverse springs 122 is 30 times, 20 times, or 10 times or less the length of the spring bars 124, the spring retains this characteristic even with a narrow structure. Therefore, the serpentine spring is suitable as the spring element 120 of the coupling device 100.

[0043] An example of such a coupling device 100 can, for example, constitute the basic structure for an annular micro electro-angular velocity sensor. Such a coupling device 100 is depicted in FIG. 3. As an example, this coupling device includes 44 spring elements 120 designed as serpentine springs, and these spring elements 120 act at regular intervals inside the ring structure 110. The width of the spring elements 120 is slightly smaller than 1 / 44 of the inner circumference of the ring structure 110, so that no gap remains between the individual spring elements 120.

[0044] Another example of the coupling device 100 is depicted in FIG. 4. Here, in addition to the ring structure 110 and the spring element 120 (which acts outside the ring structure 110 here and is depicted as a serpentine spring here as an example), the coupling device 100 has a second ring structure 130. This is connected to the (first) ring structure 110 via a plurality of spring elements 120. The first ring structure 110 is connected to the substrate 300 via the second ring structure 130.

[0045] This structure provides more flexibility regarding the application area of the coupling device 100. In particular, the coupling device 100 can also be used in measuring devices where the spring element 120 cannot be directly fixed. Furthermore, the combination with one or more additional ring structures 130 can, for example, influence the vibration behavior of the ring structure 110 by suppressing certain vibration modes or increase the flexibility, especially in the circumferential direction. The fixing of the additional ring structure 130 can be done via any connection. FIG. 4 illustrates a connection via, for example, a spoke-shaped spring 140 and an anchor block 142. However, other arbitrary forms of fixing to the substrate are also conceivable, for example via a serpentine spring or via multi-stage or more complex microelectromechanical components such as a vibration system, a mass, drive electrodes, and readout electrodes.

[0046] FIG. 5 schematically shows a microelectromechanical measuring device 400 in which the microelectromechanical coupling device 100 is used as described above.

[0047] In addition to the ring structure 110 and the spring element (depicted there as a serpentine spring as an example and not fixed to the substrate) acting on the outside of the ring structure 110, the measuring device includes two vibration systems as microelectromechanical components 200 connected to the coupling device 100 via the connection point 112. The microelectromechanical component 200 has, for example, a mass 210 and a spring structure 220 connecting the mass 210 to the ring structure 110 of the coupling device 100, respectively. Further, another connecting portion 230 between the masses 210 is depicted as an example. As can be seen from FIG. 5, the inside of the coupling device 100 can be used for the arrangement of the microelectromechanical component 200, whereby the measuring device 400 can be designed compactly.

[0048] Needless to say, when the spring element 120 is arranged inside, the microelectromechanical component 200 can also be arranged outside. Further, when the connection point 112 is correspondingly narrow, the spring element 120 and the microelectromechanical component 200 can also be arranged on the same side of the ring structure 110.

[0049] Due to the design of the ring structure 110 and the spring element 120 described above, it is guaranteed that the microelectromechanical components 200 can be optimally coupled to each other. As a result, the accuracy of the measuring device 400 and ultimately its reliability are improved.

[0050] Furthermore, all of the coupling devices described above can be used as basic components of an annular microelectromechanical angular velocity sensor in which the ring structure generates vibrations necessary for angular velocity detection.

Claims

1. A microelectromechanical coupling device (100) for coupling microelectromechanical components (200), a flexible ring structure (110) that forms a circle in a stationary state and can be deformed substantially parallel to the plane of the circle, and is suitable for coupling the microelectromechanical components (200), and a plurality of spring elements (120) suitable for connecting the ring structure (110) to a substrate (300), wherein the plurality of spring elements (120) have a small width and a low spring hardness in the circumferential direction of the ring structure (110) such that the deformability of the ring structure is homogeneous in the circumferential direction of the ring structure (110), the coupling device (100).

2. The ratio of the effective overall stiffness of the spring element (120) during operation of the coupling device (100) in the vibration mode to the product of the number of spring elements (120) and the effective stiffness of the ring structure (110) in the corresponding vibration mode is 1 or less, the coupling device (100) according to claim 1.

3. The coupling device (100) according to claim 1 or 2, wherein either all of the spring elements (120) are connected to the inside of the ring structure (110) or all of the spring elements (120) are connected to the outside of the ring structure (110).

4. The coupling device (100) according to any one of claims 1 to 3, wherein the spring element (120) is designed as a serpentine spring.

5. The coupling device (100) according to any one of claims 1 to 4, wherein the spring elements (120) are evenly arranged along the circumferential direction of the ring structure (110).

6. The number of the spring elements (120) is 4 or more, preferably 8 or more, more preferably 16 or more, the coupling device (100) according to any one of claims 1 to 5.

7. The circumferential width of the spring element (120) is 1 / 4 or less, preferably 1 / 8 or less, more preferably 1 / 16 or less of the circumference of the ring structure (110), the coupling device (100) according to any one of claims 1 to 6.

8. The spring element (120) extends along the radial direction of the ring structure (110) over less than 1 / 2 or less than 1 / 4, preferably less than 1 / 5, more preferably less than 1 / 8 of the radius of the ring structure (110) at rest, the coupling device (100) according to any one of claims 1 to 7.

9. Further comprising a second ring structure (130), The plurality of spring elements (120) are connected to the ring structure (110) and the second ring structure (130), the ring structure (110) is connected to the substrate (300) via the second ring structure (130), and the second ring structure (130) is then preferably connected to the substrate by an additional spring element (140). The coupling device (100) according to any one of claims 1 to 8.

10. A microelectromechanical coupling device (100) according to any one of claims 1 to 9, And a microelectromechanical component (200) connected to the coupling device (100). A microelectromechanical measuring device (400).

11. Comprising a microelectromechanical coupling device (100) according to any one of claims 1 to 9, The ring structure (110) is suitable for generating excitation vibrations, and the excitation vibrations are superimposed on detection vibrations generated by a Coriolis force during rotation of the ring structure (110), An annular microelectromechanical angular velocity sensor in which the spring element (120) constitutes the microelectromechanical component.

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