WO2025002605A1 - Microelectromechanical coupling device - Google Patents

Abstract

A microelectromechanical coupling device (100) for coupling microelectromechanical components has a flexible ring structure (110) that, at rest, forms a circle that can be deformed substantially parallel to the plane of the circle and that is suitable for coupling the microelectromechanical components, and a plurality of spring elements (120) that are suitable for connecting the ring structure (110) to a substrate (200). Each spring element (120) in this arrangement has at least one tangential spring (122) that can be deflected substantially tangentially with respect to the ring structure (110), and at least one radial spring (124) that can be deflected substantially in the radial direction of the ring structure (110). The tangential spring (122) and the radial spring (124) of each spring element (120) are stand-alone components and the ratio of spring stiffnesses of the tangential spring (122) and the radial spring (124) of each spring element (120) is configured in such a way that a vibration that deforms the ring structure (110) is more advantageous in terms of energy than a vibration that displaces the ring structure (110) in translation and/or in rotation with respect to the substrate (200) and/or in such a way that the natural frequency of the translational and/or rotational vibration and the nearest natural frequency of a deforming vibration are at an interval that is greater than 5% of the natural frequency of this deforming vibration.

Description

microelectromechanical coupling device

The present invention relates to a microelectromechanical coupling device for coupling microelectromechanical components and a ring gyroscope with such a coupling device.

In micromechanical measuring devices such as yaw rate or acceleration sensors, different micromechanical components, such as vibration systems or masses, often have to be connected to each other in order to couple the respective movements.

Often, a coupling by means of a freely floating, non-supported ring would be desirable, as this reacts to a radial force with a deflection that has the same amplitude regardless of the point in the circumferential direction at which the radial force is applied. It can also be advantageous to use a freely floating ring as a rotation rate sensor, in which a detection oscillation is superimposed on an excitation oscillation during rotation due to the Coriolis force.

The problem here is that without any connection to a substrate of the measuring device, translational modes, rotational modes in which the ring rotates as a whole, or other parasitic modes form the first eigenmodes. However, these are not desired. In addition, the production of an unsupported ring for coupling microelectromechanical components involves a great deal of effort in terms of production technology.

One known example is the use of systems with several rings that are connected to one another by stiff, short connections (so-called spokes). The spokes themselves are very space-saving. However, the need to have several rings in order to obtain the appropriate bearings partially compensates for this space saving. In addition, the spokes do not have resonances in the range of a few kHz due to their stiffness. It is also difficult to achieve homogeneous behavior in the circumferential direction with this structure. Alternatively, extremely long and therefore space-consuming, but also very soft springs are used. Although low resonance frequencies can be achieved with these, the deviations from the ideal ring are very large here too, since homogeneous behavior in the circumferential direction cannot be achieved.

The object of the present invention is therefore to provide a micromechanical coupling device or a ring gyroscope in which the excitation of translational modes can be suppressed and at the same time installation space can be saved compared to the known solutions.

This object is solved by the subject matter of claim 1.

A microelectromechanical coupling device for coupling microelectromechanical components has a flexible ring structure which forms a circle at rest, which can be deformed substantially parallel to the plane of the circle and which is suitable for coupling the microelectromechanical components; and a plurality of spring elements which are suitable for connecting the ring structure to a substrate. Each spring element has at least one tangential spring which can be deflected substantially tangentially to the ring structure and at least one radial spring which can be deflected substantially in the radial direction of the ring structure. The tangential spring and the radial spring of each spring element are independent components and the ratio of spring stiffnesses of the tangential spring and the radial spring of each spring element is designed such that an oscillation that deforms the ring structure is energetically more favorable than an oscillation that displaces the ring structure translationally and/or rotationally relative to the substrate and/or that the natural frequency of the translational and/or rotational oscillation and the closest natural frequency of a deforming oscillation have a distance that is greater than 5% of the natural frequency of this deforming oscillation. The distance between the natural frequencies is preferably in a range from 5% to 200%, more preferably from 5% to 100%, more preferably from 5% to 50% of the natural frequency of the deforming oscillation.

The coupling device therefore has a ring as a basic structure which is mounted above a substrate and has, for example, the shape of a self-contained web, the height of which perpendicular to the substrate is a multiple of its width parallel to the substrate. In the resting position, this ring forms a circle in the broadest sense, ie a closed curve that lies parallel to the substrate. A deformation of the ring is then essentially only possible parallel to the substrate, ie deflections perpendicular to the substrate are negligible for operation.

In order to suppress the translational and/or rotational mode or vibration, the ring structure is connected to the substrate via spring elements that are composed of tangential springs and radial springs, i.e. springs that can be deflected essentially tangentially to the ring structure or perpendicularly to the ring structure. The spring stiffnesses of the tangential and radial springs can be adjusted independently of one another by appropriately dimensioning the springs during the design and manufacture of the coupling device. In this way, a ratio of the spring stiffnesses of the tangential and radial springs of each spring element can be adjusted in which the translational mode or other disturbing modes such as rotational modes are energetically disadvantaged compared to at least one "real" vibration mode, i.e. one that deforms the ring structure, hereinafter also referred to as bending mode. This ensures that the ring structure deforms as desired when excited and does not simply move sideways.

Additionally or alternatively, by adjusting the ratio of the spring stiffness of the tangential and radial springs, it is possible to ensure that the natural frequency of the translational mode and/or the rotational mode differs sufficiently from the closest natural frequency of the bending mode. This ensures that a force impulse on the coupling device that excites the translational mode, for example, does not couple into the vibration mode that is actually intended and disturb it. In this way, disturbances to an operating vibration of the ring structure can be prevented.

The possibility of achieving the above-mentioned effects by providing independently acting tangential and radial springs can be understood as follows.

In the first non-translational vibration mode, the ring vibrates in the form of an ellipse. At any given time, two vibration nodes, i.e. locations with maximum amplitude, are formed. This mode is therefore also called n = 2 eigenmode. Further bending Eigenmodes with multiple antinodes are referred to as n = 3, 4, 5,... eigenmodes.

Due to the elliptical shape of the n = 2 eigenmodes, the deviation of the ring from the circular shape in cylindrical coordinates can be parameterized for each point as follows: <t> _r ,i = cos(20) for the radial direction and <t> e,i = - sin(26) for the tangential direction. The angle 0 describes the circumferential angle.

The points on the ring therefore experience both a radial and a tangential deflection. The tangential deflection is a maximum of half the size of the radial deflection. In addition, the sum of the radial deflection of the points is greater than the sum of the tangential deflection. There is therefore more radial deflection than tangential deflection.

There are points that only experience a radial or tangential deflection, and points that experience a superimposed deflection in the radial and tangential directions.

If spring elements are used to suspend a ring structure that have independently deflectable radial and tangential springs, the deflections in the radial and tangential directions can be controlled via the ratio of the spring stiffness of the tangential springs and the radial springs of each spring element. The greater the spring stiffness in the tangential direction compared to the spring stiffness in the radial direction, the less the tangential spring will deflect compared to the radial spring with the same amount of force. Accordingly, the ring structure can also be deformed less easily in the tangential direction than in the radial direction if the spring stiffness of the tangential springs is high compared to the spring stiffness of the radial springs.

In contrast to the n=2 eigenmode, a ring does not deform during a translational movement, but behaves approximately like a rigid body with a mass. If the ring structure coupled to the substrate by means of the spring elements moves purely translationally over the substrate, only the spring elements are deformed, but not the ring structure. The deflection of the spring elements differs from the deflection of the spring elements in the n=2 eigenmode. Here, the tangential deflection no longer applies. is a maximum of half the radial deflection. In addition, the sum of the tangential deflection of the points is larger than in the case of the n=2 eigenmode. The sum of the radial deflections remains approximately unchanged.

A ring behaves analogously in a rotational mode. Here, the ring rotates as a rigid body around the central axis and only the springs are deflected. In this case, the springs are deflected approximately exclusively in the tangential direction.

Accordingly, the translational mode and the rotational modes of the ring structure can be suppressed or shifted to higher frequencies by using independent radial and tangential springs in each of the spring elements, because their separately adjustable spring stiffnesses can suppress a deflection of the ring structure in the tangential direction by more than half of the deflection in the radial direction. The n = 2 eigenmode can therefore be energetically favored compared to the translational mode and/or rotational mode.

The same applies to the higher bending eigenmodes (n=3, 4, 5, ...). These modes can also be given a higher energy advantage than the translational/rotational mode by appropriately designing the radial and tangential springs of the spring elements. Accordingly, by adjusting the spring stiffnesses, the natural frequencies of the vibration/bending eigenmodes can also be separated from the natural frequency of the translational mode and/or rotational mode.

The spring elements can be designed such that the ratio of the spring stiffness of the tangential spring to the spring stiffness of the radial spring is in a range from 1 to 3. This ensures that the translational mode and/or rotational mode is not the most energetically favorable mode or that its natural frequency is sufficiently far from the (or at least one) natural frequency of the bending eigenmodes.

The ring structure can be suitable for being excited to oscillations with an amplitude, preferably in the range between 0.1 pm and 10 pm, in which the spring stiffnesses of the tangential springs and the radial springs remain constant. This means that both the tangential Both the radial springs and the ring structure remain in the linear range during vibrations that occur when the coupling device is in operation, in which the deflection is directly proportional to the deflecting force, ie in which the spring stiffness is constant. This can be achieved in particular by the separate design of the tangential and radial springs, which can cushion the movements in their respective preferred direction.

The spring elements can have a radial extension of less than 25% of the radius of the ring structure in the resting state. This is also made possible by the separate design of tangential and radial springs. In particular, the radial springs can be narrow in the radial direction of the ring structure and, for example, only take up 10% or 5% of the radius of the ring structure. Since the tangential springs only have to/should allow a smaller deflection than the radial springs, they can also be designed to be compact. This enables a compact suspension of the ring structure and thus a compact design of the coupling device.

The spring elements can be connected to the ring structure from the outside. This allows the installation space inside the ring structure to be kept free, e.g. for other components with additional functionality. Due to the small space requirement of the spring elements, not much space is required on the outside of the ring structure either. The coupling device can therefore be compact and yet still have increased functionality.

Each spring element can be designed in such a way that less than half the space is available for deflections of the tangential spring in the tangential direction than for deflections of the radial spring in the radial direction. As shown above, vibrations of the ring structure should be energetically preferred where the tangential movement component of the ring structure is only a maximum of half as large as the radial movement component. Accordingly, the installation space to be kept free for the tangential movements can be reduced and the space freed up can be used for other components. This makes the coupling device more compact and can still be equipped with a large number of components.

Electrodes for exciting and/or reading vibrations of the ring structure can be arranged between the spring elements in the circumferential direction of the ring structure. This makes the ring structure particularly compact. Each of the electrodes can extend circumferentially over an angle of between 10° and 45° measured from the center of the ring structure, preferably over an angle of between 15° and 30° and more preferably over an angle of 18°. This places the electrodes in contact with large, continuous sections of the ring structure. This reduces the voltage on the electrodes required for a force to be applied/read. This makes the operation of the coupling device more efficient.

The spring elements can be evenly distributed in the circumferential direction of the ring structure. This facilitates the manufacture of the coupling device.

Each spring element can connect the ring structure to the substrate via exactly one anchor structure. This reduces the damping mechanism of the so-called "anchor losses". Anchor losses occur when forces are introduced into the substrate via several points, which can then only be balanced at the level of the substrate. The "anchor losses" describe the energy that is introduced into the substrate by forces and moments on the anchors and dissipates into the environment via the substrate and is thus lost. This can be counteracted by balancing forces and moments and transferring these forces and moments to the substrate at as few and as central points as possible. Accordingly, the use of only one anchor structure reduces the occurrence of such anchor losses.

In each spring element, the radial spring may comprise a double-folded cantilever spring extending in the tangential direction and connected in the radial direction to the substrate and the tangential spring, and the tangential spring may be a cantilever spring folded more than twice or comprise at least two double-folded cantilever springs extending in the radial direction and connected in the radial direction to the radial spring and the ring structure. This makes it easy to manufacture spring elements corresponding to the above.

A ring gyroscope can have a micromechanical coupling device as described above. The ring structure can be suitable for carrying out an excitation oscillation, which, when the ring structure is rotated, generates a force generated by the Coriolis force. detection oscillation is superimposed. The spring elements represent the microelectromechanical components. In this way, a ring gyroscope can be realized in which the undesired translational mode or its natural frequency can be sufficiently separated from the desired operating modes or their frequencies.

The so-called “angular gain” of the second natural oscillation of the ring structure, which is formed from the ratio of Coriolis mass to twice the modal mass, can be in a range between 0.3 and 0.4, preferably in a range between 0.35 and 0.4 and more preferably in a range between 0.38 and 0.4, with the end points being part of the specified ranges. The modal mass describes the proportional mass of the associated natural oscillation, i.e. an effective mass of the corresponding natural oscillation. It results from the eigenvector of the corresponding mode and the mass distribution. The Coriolis mass is made up of all mass points that move in the direction of the exciting oscillation during an excited oscillation and in the direction of the detection oscillation during detection. The so-called “angular gain” can be determined from the ratio of Coriolis mass and modal mass. The theoretical maximum angular gain is 1 (Foucault pendulum). A large angular gain is advantageous and can be understood as the amplification factor of the angular rate signal. Theoretically, the angular gain of a ring gyroscope in the n = 2 eigenmode is 0.4. With the coupling device described above, operated as a ring gyroscope, an angular gain can be achieved that is extremely close to this theoretical value.

The invention is further described below with reference to the figures. The figures and their description are purely exemplary. The present invention is defined solely by the subject matter of the claims. It shows:

Fig. 1A and 1B show a schematic representation of a microelectromechanical coupling device;

Fig. 2 is a schematic representation of a spring element formed from a combination of a tangential spring and a radial spring; Fig. 3A and 3B are schematic representations of the deflections of the radial spring and the tangential spring of Fig. 2;

Fig. 4 is a schematic representation of another spring element;

Fig. 5 is a schematic representation of another spring element;

Fig. 6 is a schematic representation of another spring element;

Fig. 7 is a schematic representation of another spring element;

Fig. 8 is a schematic representation of another spring element;

Fig. 9 is a schematic representation of a ring gyroscope constructed from a microelectromechanical coupling device;

Fig. 10 is a schematic representation of another ring gyroscope; and

Fig. 11 is a schematic representation of the arrangement of electrodes and spring elements in a coupling device.

Figs. 1A and 1B show a schematic representation of a microelectromechanical coupling device 100, which is suitable for coupling microelectromechanical components, such as those used in microelectromechanical measuring devices such as rotation rate and/or acceleration sensors. The microelectromechanical coupling device 100 can also form the basic structure of a ring-shaped rotation rate sensor. Fig. 1B is a section through Fig. 1A along the line l-l.

The coupling device 100 has a flexible ring structure 110 and a plurality of spring elements 120. As shown in Fig. 1A, the ring structure forms a circle at rest and can be deformed essentially parallel to the plane of the circle. As can be seen from Fig. 1B, the ring structure 110 has a substantially rectangular shape perpendicular to the plane of the circle or perpendicular to a substrate 200 over which the ring structure 110 is mounted. Cross-section with long sides perpendicular to the substrate 200, which are many times longer than the short sides parallel to the substrate 200. The ring structure 110 can therefore be viewed, for example, as a self-contained bending beam spring that can deform parallel to the substrate 200, with deformations perpendicular to the substrate 200 being negligible (in a first approximation). The shape of the ring structure 110 shown is purely exemplary. The ring structure 110 can have any shape that essentially only promotes deformation parallel to the substrate plane. The ring structure 110 can also have a degenerate circular shape in the rest position and be designed, for example, as an ellipse or as a polygon with rounded corners. Such degenerate circular shapes should therefore also be covered by the reference to the circular ring structure 110.

Coupling points 112 are indicated on the ring structure 110, at which the microelectromechanical components to be coupled engage or at which these components are connected to the ring structure 110. The coupling allows movements between the microelectromechanical components to be transmitted or coordinated. In particular, the coupling device 100 can mediate a force- and torque-free push-pull oscillation between the components. The microelectromechanical components can be, for example, sensor masses or oscillation systems. In principle, however, the type, structure and size of the components 200 to be coupled are arbitrary. Likewise, the number of components 200 can be greater than two.

The coupling can also be carried out via the spring elements 120. In this case, the coupling points 112 are missing. In particular, if the coupling device 100 is part of a ring-shaped microelectromechanical rotation rate sensor, such as a ring gyroscope, the spring elements 120 can represent the microelectromechanical components. The ring structure is suitable for executing an excitation oscillation, on which a detection oscillation generated by the Coriolis force is superimposed when the ring structure 110 rotates.

The ring structure 110 is connected to the substrate 200 via a plurality of spring elements 120. The spring elements 120 engage at various points of the ring structure 110 and hold it above the substrate 200. As shown in Figs. 1A and 1B, the spring elements 120 can be connected to anchor structures 125 and the ring structure 110 can be directly to the substrate 200. The anchor structures 125 can have any

shape as long as they allow a firm connection to the substrate 200.

As shown schematically in the enlargement of Fig. 1A, each spring element 120 has at least one tangential spring 122, which can be deflected substantially tangentially to the ring structure 110, and at least one radial spring 124, which can be deflected substantially in the radial direction of the ring structure 110.

The tangential spring 122 and the radial spring 124 are shown completely schematically in Fig. 1A by means of spiral spring symbols. These springs can have any shape, as long as the tangential spring 122 and the radial spring 124 of each spring element 120 are independent components and the ratio of spring stiffnesses of the tangential spring 122 and the radial spring 124 of each spring element 120 is designed such that an oscillation deforming the ring structure 110 is energetically more favorable than an oscillation that displaces the ring structure 110 translationally relative to the substrate 200 and/or that the natural frequency of the translational oscillation and the closest natural frequency of a deforming oscillation have a distance that is greater than 5% of the natural frequency of this deforming oscillation. Preferably, the distance between the natural frequencies is in a range from 5% to 200%, more preferably from 5% to 100%, more preferably from 5% to 50% of the natural frequency of the deforming vibration.

The spring elements 120 therefore consist of springs that can be deformed essentially independently of one another and that divide the overall movement/deformation of the spring elements 120 into a radial component and a tangential component, whereby the radial component is generated by the deformation of the radial spring 124 and the tangential component by a deformation of the tangential spring 122. The tangential spring 122 and the radial spring 124 are each separate assemblies, the dimensions and properties of which can be set separately during the manufacturing process of the coupling device 100. In particular, the masses and thicknesses of the tangential springs 122 and the radial springs 124 can be designed differently, e.g. in an etching process, in order to achieve different spring stiffnesses. In this way, the ratios of the spring stiffness of the tangential springs 122 to the radial springs 124 can be set such that a translational or rotational oscillation of the ring structure 110, ie an oscillation without deformation of the ring structure 110, is energetically less favorable than an oscillation that deforms the ring structure 110. Preferably, the second natural oscillation of the freely floating ring structure 110, ie the n = 2 natural mode, in which two oscillation antinodes form, should become energetically more favorable than the translation or translational mode and/or rotational mode due to the connection to the spring elements 120. The ratio of the spring stiffnesses in the individual spring elements 120 can also be set in such a way that the eigenmodes of the freely floating ring structure 110 are rearranged, ie that, for example, the n = 3 eigenmode of the freely floating ring structure 110 becomes energetically more favorable than the n = 2 eigenmode due to the coupling with the spring elements 120. For this purpose, the ratios of the spring stiffnesses in the individual spring elements 120 can also be designed differently.

Instead of rearranging the excitation energies of the individual eigenmodes of the freely floating ring structure 110 (or in addition to this), the ratio of the spring stiffnesses of the tangential spring 122 and the radial spring 124 can also be set such that the eigenfrequencies of the eigenmodes are sufficiently far apart. In particular, the eigenfrequency of the translational mode and/or rotational mode should be sufficiently far away from the initial eigenfrequency of a bending mode that deforms the ring structure 110 in order to ensure that force impulses exciting the translational mode do not couple into this bending mode and disturb it. For this purpose, the eigenfrequencies can, for example, have a distance of more than 5% of the eigenfrequency of the bending mode. The distance between the eigenfrequencies is preferably in a range from 5% to 200%, more preferably from 5% to 100%, more preferably from 5% to 50% of the eigenfrequency of the deforming vibration.

The spring elements 120 can in particular be designed such that the ratio of the spring stiffness of the tangential spring 122 to the spring stiffness of the radial spring 124 is in a range from 1 to 3. If the spring stiffness of the tangential spring 122 is selected to be greater than that of the radial spring 124, tangential movements are suppressed. This favors movement patterns such as the n = 2 eigenmode, in which the maximum tangential deflection is smaller than the maximum radial deflection. For the same reason, each spring element 120 can also be designed in such a way that less than half the space is available for deflections of the tangential spring 122 in the tangential direction than for deflections of the radial spring 124 in the radial direction. On the one hand, this suppresses the translational mode itself. On the other hand, the space in the tangential direction is not required if the spring elements 120 are adjusted accordingly and can be used for the placement of other components, such as electrodes.

In particular, the ring structure 110 should oscillate with such a small amplitude, preferably in the range between 0.1 pm and 10 pm, that the spring stiffness of the tangential springs 122 and the radial springs 124 remain constant. The spring elements 120 therefore behave like linear springs in the deflection range of the ring structure 110. The linearity of the spring elements 120 is also due to the separation of tangential springs 122 and radial springs 124. This separation allows the deflections taking place parallel to the substrate 200 in each direction to be split into a radial and a tangential part and absorbed by the corresponding spring. This prevents parts of the spring elements 120 from being deflected in their preferred directions, i.e. in directions in which they leave the linearity range even with small deflections. This makes the vibration of the ring structure 110 easier to control.

The above-described design of the coupling device allows excitations of the translational mode to be effectively suppressed compared to excitations of bending modes. The separation of the spring elements 120 into tangential springs 122 and radial springs 124 also allows a compact design of the spring elements 120, so that the suppression of the translational mode can be achieved together with a compact design of the coupling device 100.

The spring elements 120 can in particular have a radial extension of less than 25% of the radius of the ring structure 110 in the resting state, whereby the coupling device 100 becomes particularly compact. This makes it possible to place further components in or around the ring structure 110. The spring elements 120 can be connected to the ring structure 110 from the inside, as shown in Fig. 1A. Due to their compact design, a large part of the interior of the ring structure 110 remains free. However, they can also be connected to the ring structure 110 from the outside, since their small size does not lead to an excessive enlargement of the coupling device. This allows the interior of the ring structure 110 to be made completely free for the arrangement of further components, which is not possible, for example, in designs from the prior art in which the ring structure is held by long, centrally anchored springs or by large frame structures.

The spring elements 120 can, as shown in Fig. 1A, in principle be distributed irregularly along the ring structure 110 if this is advantageous for the intended suppression of the translational mode. Preferably, however, the spring elements are evenly distributed in the circumferential direction of the ring structure 110, as this facilitates production. In addition, the ring structure 110 can be excited more easily in a homogeneous manner.

As shown in Figs. 1A and 1B, each spring element 120 connects the ring structure 110 to the substrate 200 via exactly one anchor structure 125. This avoids anchor losses. These arise when forces are introduced into the substrate via several points, which can then only be balanced at the level of the substrate. The anchor losses describe the energy that is introduced into the substrate by forces and moments on the anchors and dissipates into the environment via the substrate and is thus lost. This can be counteracted by balancing forces and moments and by transferring these forces and moments to the substrate at as few and as central points as possible. Accordingly, the use of only one anchor structure reduces the occurrence of such anchor losses.

As shown in Fig. 1A, the coupling device 110 can have a plurality of spring elements 120. However, the number of spring elements 120 can also be different. For example, 4, 8, 16, 24 or 32 spring elements 120 can be used.

In Figs. 2 to 8, different variants of spring elements 120 are shown. These variants have in common that in the spring elements 120, the radial spring 124 is a double-folded Bending beam spring that extends in the tangential direction and is connected in the radial direction to the substrate 200 and the tangential spring 122, and the tangential spring 122 is a bending beam spring that is folded more than twice or has at least two double-folded bending beam springs that extend in the radial direction and are connected in the radial direction to the radial spring 124 and the ring structure 110. In principle, other configurations are of course also possible, as long as the tangential spring 122 and the radial spring 124 can be represented separately. For example, it is possible to attach the radial spring 124 to the ring structure and the tangential spring 122 to the substrate 200.

Fig. 2 shows a spring element 120 in which the radial spring 124 is designed as a double-folded bending beam spring that creates a connection between an anchor point 125 and the tangential spring 122. This means that a bending beam that extends in a tangential direction is connected, preferably in its center, to the anchor structure 125. At each end, the bending beam is folded by 360°, i.e. it runs back in parallel and thus forms a second bending beam that runs parallel to the first bending beam. The two bending beams are connected at their ends. Such a structure can be produced in a manner known per se by an etching process.

The tangential spring 122 consists of a bending beam spring that runs in a radial direction from a (preferably centrally located) connection point with the radial spring 124 to the ring structure 110. At the end of this bending beam spring there is a double-folded bending beam spring that is folded in such a way that it runs like a serpentine. The long sides of the serpentines run parallel to the centrally located bending beam spring, i.e. in a radial direction. In the example in Fig. 2 there are 3 serpentines, with the connection to the radial spring 124 and the ring structure 110 being made at a central point. However, other numbers of serpentines are also possible.

The deflections of this spring element 120 are shown in greatly exaggerated form in Figs. 3A and 3B. Fig. 3A shows the deflection in the radial direction r, in which essentially only the radial spring 124 is deformed. Fig. 3B shows the deflection in the tangential direction t, in which essentially only the tangential spring 122 is deformed. By appropriately selecting the dimensions of the cantilever springs that form the tangential spring 122 and the radial spring 124, e.g. by selecting the etching parameters during manufacture, the spring stiffness of the springs can be adjusted independently of one another. The spring element 120 shown in Fig. 2 is also extremely compact. Its use in a coupling device 100 as described above therefore allows the translational mode to be suppressed without consuming excessive installation space.

The spring element 120 shown in Fig. 4 corresponds to the design of Fig. 2, except for the use of two double-folded bending beam springs in the radial spring 124. This allows the parameters of the radial spring 124 to be adjusted even more flexibly.

The spring element 120 shown in Fig. 5 uses pairs of bending beam springs arranged in a fork shape as the tangential spring 122, i.e. pairs of bending beam springs connected at one end and connected to one another at their other end. This design also allows the spring parameters of the tangential spring 122 and the radial spring 124 to be set independently of one another.

Figures 6 and 7 show two variants of a “two-pronged bending beam fork” which is connected to the radial spring 124 or the ring structure 110 via a single bending beam. These designs are particularly compact in the tangential direction.

Fig. 8 shows a variant in which the tangential spring 122 consists of two double-folded bending beam springs, which are connected by a frame to the radial spring 124 and a bending beam spring anchored to the ring structure 110. In addition, the radial spring 124, designed as a double-folded bending beam spring, is not continuous here, but merges into the frame.

The examples in Figs. 2 to 8 should make it clear that there are a multitude of different designs for the spring elements 120, which allow the ratio of the spring stiffnesses of the tangential spring 122 and the radial spring 124 to be freely adjusted within the framework of the manufacturing conditions in order to suppress the translational mode. Fig. 9 shows a coupling device 100 in which the coupled microelectromechanical components are the spring elements 120. This means that the coupling device 100 corresponds to a deformable ring that is spring-loaded above the substrate 200. This can be used as a ring gyroscope 300 because the ring structure 110 is suitable for executing an excitation oscillation, which is superimposed by a detection oscillation generated by the Coriolis force when the ring structure 110 rotates. If the ring structure 110 is set into oscillation, e.g. by using excitation electrodes, a rotation of the ring structure 110 leads to a change in this oscillation, which can be read out, e.g. via detection electrodes, in order to determine the rotation rate of the rotation.

Here, the suppression of the translational mode, or the separation of the natural frequency of the translational mode from the operating frequency/excitation frequency of the ring gyroscope 300, is particularly advantageous because this can reduce interference with the measurement. This improves the measurement accuracy of the ring gyroscope 300.

As shown in Fig. 10, several concentric rings which are connected to each other with short springs, e.g. with short radial bending beams or webs, can also be used as the ring structure 110 of a ring gyroscope 300, e.g. to increase the mass of the oscillating ring structure 110.

As can be seen from Figs. 9 and 10, the spring elements 120 are designed to be compact (smaller than 1/4 of the radius) compared to the dimensions of the ring structure 110 and therefore hardly increase the installation space for the ring gyroscope 300 compared to the ring structure 110 without spring elements 120.

Electrodes 140 for exciting and/or reading out vibrations of the ring structure 110 can be arranged between the spring elements 120 both when used as a ring gyroscope 300 and generally in the circumferential direction of the ring structure 110. This is shown as an example in Fig. 11. In this way, vibrations of the ring structure 110 can be excited or measured in a compact manner. In addition, the electrodes 140 can almost completely surround the ring structure 110 in the circumferential direction, whereby a homogeneous response behavior of the ring structure 110 can be achieved. As shown in Fig. 11, the electrodes 140 can be moved relatively close to the tangential springs 122, since these are deflected only comparatively little due to the suppressed translation mode. This improves the interaction between the electrodes 140 and the ring structure 110 and thus the response behavior of the ring structure 110. In addition, the voltage at the electrodes required for a force to be applied/read out is reduced.

Each of the electrodes 140 can extend in the circumferential direction over an angle of between 10° and 45° measured from the center of the ring structure 110, depending on the number of spring elements 120 used. An angle range of between 15° and 30° has proven to be preferred, when using 10 to 20 spring elements 120. For example, 16 spring elements 120 evenly distributed in the circumferential direction along the ring structure 110 can be used and the electrodes 140 can each assume an angle of 18°. In this way, 80% of the circumferential direction of the ring structure 110 can be provided with electrodes 140. In general, an arrangement of electrodes 140 in a range of 70% to 90% of the circumferential direction of the ring structure 110 can be considered advantageous for the response behavior of the ring structure 110.

In the ring gyroscope 300, the angular gain (the ratio of Coriolis mass to twice the modal mass) of the second eigenmode, i.e. the n = 2 eigenmode, of the ring structure 110 can be in a range between 0.3 and 0.4, preferably in a range between 0.35 and 0.4, and more preferably in a range between 0.38 and 0.4 (endpoints included).

The modal mass describes the proportionate mass of the corresponding natural oscillation, i.e. an effective mass of the corresponding natural oscillation. It results from the eigenvector of the corresponding mode and the mass distribution. The Coriolis mass is made up of all mass points that move in the direction of the exciting oscillation during an excited oscillation and in the direction of the detection oscillation during detection. The so-called "angular gain" can be determined from the ratio of Coriolis mass and modal mass. The theoretical maximum angular gain is 1 (Foucault pendulum). A large angular gain is advantageous and can be used as a gain. factor of the angular rate signal. Theoretically, the angular gain of a ring gyroscope in the n = 2 eigenmode is 0.4. With the coupling device 100 described above, operated as a ring gyroscope 300, an angular can be achieved that comes extremely close to this theoretical value. This is due to the suppression of the translational mode.

Claims

claims 1. Microelectromechanical coupling device (100) for coupling microelectromechanical components, comprising a flexible ring structure (110) which forms a circle at rest, which can be deformed substantially parallel to the plane of the circle and which is suitable for coupling the microelectromechanical components; and a plurality of spring elements (120) which are suitable for connecting the ring structure (110) to a substrate (200); wherein each spring element (120) has at least one tangential spring (122) which can be deflected substantially tangentially to the ring structure (110) and at least one radial spring (124) which can be deflected substantially in the radial direction of the ring structure (110); the tangential spring (122) and the radial spring (124) of each spring element (120) are independent components; and the ratio of spring stiffnesses of the tangential spring (122) and the radial spring (124) of each spring element (120) is designed such that an oscillation deforming the ring structure (110) is energetically more favorable than an oscillation displacing the ring structure (110) translationally and/or rotationally relative to the substrate (200) and/or that the natural frequency of the translational and/or rotational oscillation and the closest natural frequency of a deforming oscillation have a distance that is greater than 5% of the natural frequency of this deforming oscillation. 2. Coupling device (100) according to claim 1, wherein the spring elements (120) are designed such that the ratio of the spring stiffness of the tangential spring (122) to the spring stiffness of the radial spring (124) is in a range of 1 to 3. 3. Coupling device (100) according to one of the preceding claims, wherein the ring structure (110) is suitable for being excited to oscillations with an amplitude, preferably in the range between 0.1 pm and 10 pm, in which the spring stiffnesses of the tangential springs (122) and the radial springs (124) remain constant. 4. Coupling device (100) according to one of the preceding claims, wherein the spring elements (120) have a radial extent of less than 25% of the radius of the ring structure (110) in the rest state. 5. Coupling device (100) according to one of the preceding claims, wherein the spring elements (120) are connected from the outside to the ring structure (110). 6. Coupling device (100) according to one of the preceding claims, wherein each spring element (120) is designed such that less than half the space is available for deflections of the tangential spring (122) in the tangential direction than for deflections of the radial spring (124) in the radial direction. 7. Coupling device (100) according to one of the preceding claims, wherein electrodes (140) for exciting and/or reading vibrations of the ring structure (110) are arranged in the circumferential direction of the ring structure between the spring elements (120). 8. Coupling device (100) according to claim 7, wherein each of the electrodes (140) extends circumferentially over an angle measured from the center of the ring structure (110) between 10° and 45°, preferably over an angle between 15° and 30°, and more preferably over an angle of 18°. 9. Coupling device (100) according to one of the preceding claims, wherein the spring elements (120) are evenly distributed in the circumferential direction of the ring structure (110). 10. Coupling device (100) according to one of the preceding claims, wherein each spring element (120) connects the ring structure (110) to the substrate (200) via exactly one anchor structure. 11. Coupling device (100) according to one of the preceding claims, wherein in each spring element (120) the radial spring (124) comprises a double-folded bending beam spring which extends in the tangential direction and which is connected in the radial direction to the substrate (200) and the tangential spring (122) are connected, and the tangential spring (122) is a more than double-folded cantilever spring or has at least two double-folded cantilever springs which extend in the radial direction and which are connected in the radial direction to the radial spring (124) and the ring structure (110). 12. Ring gyroscope (300) with the micromechanical coupling device (100) according to one of the preceding claims; wherein the ring structure (110) is suitable for executing an excitation oscillation, on which a detection oscillation generated by the Coriolis force is superimposed upon rotation of the ring structure (110); and the spring elements (120) represent the microelectromechanical components. 13. Ring gyroscope (300) according to claim 12, wherein the angular gain, i.e. the ratio of Coriolis mass to twice the modal mass, of the second natural oscillation of the ring structure (110) is in a range between 0.3 and 0.4, preferably in a range between 0.35 and 0.4 and more preferably in a range between 0.38 and 0.4, wherein the end points are part of the specified ranges.