The present application claims priority to and the benefit of German patent application no. 10 2013 216 935.3, which was filed in Germany on Aug. 26, 2013, the disclosure of which is incorporated herein by reference.
The present invention is based on a rotational rate sensor.
Such rotational rate sensors are generally known. For example, it is generally known that rotational rate sensors have a driven mass on which a Coriolis force can act, and a deflection resulting therefrom can be detected. Typically, as a result of the production process there are asymmetrical realizations of sensor elements of the rotational rate sensors, so that for example disturbing forces, or oblique forces, are produced that increase in linear fashion with the deflection. Such force components are standardly referred to as quadrature forces. These quadrature forces are a problem because it is often the case that, due to the magnitude of these quadrature signals, it is difficult to recognize a Coriolis force. For example, for the separate detection of quadrature forces and Coriolis forces, a comparatively high input range of a measurement electronics system of the rotational rate sensor is required. Constructive measures are known in which quadrature forces can be compensated already in the sensor element through electrical counter-forces. Standardly, the quadrature forces occur in both directions.
It is therefore an object of the present invention to provide a rotational rate sensor, a method for producing a rotational rate sensor, and/or an improved quadrature compensation method, in which the constructive size of the rotational rate sensor is reduced and/or the evaluation circuit can be made with a simpler configuration, while nonetheless achieving a reliable quadrature compensation.
In comparison with the existing art, the rotational rate sensor according to the present invention, the method according to the present invention for producing a rotational rate sensor, and the quadrature compensation method according to the present invention according to the coordinate claims have the advantage that through the exclusively one compensation arrangement configured to produce the compensating force, or through the quadrature offset force directed exclusively in the preferred direction, the constructive size of the rotational rate sensor is reduced, while a reliable quadrature compensation is nonetheless achieved. In this way, a further compensating arrangement, configured to produce a different compensating force acting on the second mass element and directed opposite to the compensating force, is saved. In contrast to the known rotational rate sensors, the rotational rate sensor is configured in such a way that it is sufficient to preset compensating forces having a directional sign. In particular, the rotational rate sensor is fashioned in such a way that already as a result of its configuration a defined quadrature offset force, here also referred to as an oblique force or artificial quadrature, is impressed. This is done with the goal that further oblique forces resulting due to the production process produce, in sum together with the preset quadrature offset force, only overall quadrature forces having exclusively one directional sign. This means for example that the overall quadrature force results from a quadrature force and the additionally produced quadrature offset force, the quadrature offset force always being directed in the preferred direction, independent of the orientation of the quadrature force, and being significantly greater than the quadrature force. In this way, advantageously in particular only the at least one compensating arrangement is required for the compensation of the quadrature, because only one force sign is applied. In particular, the at least one compensating arrangement is configured as a quadrature compensation electrode.
The rotational rate sensor may be configured for the detection of a further rotational rate about a further axis of rotation perpendicular to the axis of rotation, the rotational rate sensor having at least one further compensating arrangement. The rotational rate sensor may be configured for the detection of a still further rotational rate about a still further axis of rotation perpendicular to the axis of rotation and to the further axis of rotation, the rotational rate sensor having at least one still further compensating arrangement. In this way, according to the present invention for each axis of rotation a compensating arrangement, in particular a compensating electrode, its wiring, and an associated connection to the evaluation circuit of the rotational rate sensor, is saved. In this way, the constructive size of the rotational rate sensor and the production costs are still further reduced. In particular in rotational rate sensors having bonding pad lines, the number of sensor connections to a contact arrangement for connecting the rotational rate sensor to an external connecting arrangement is a limiting factor for the system size or extension of the rotational rate sensor. Here as well, according to the present invention it is advantageously possible to further reduce the space requirement. In addition, savings of for example production costs are also conceivable through possible optimizations in an evaluation circuit of the rotational rate sensor according to the present invention.
Advantageous embodiments and developments of the present invention can be learned from the subclaims and from the description with reference to the drawings.
The substrate may have a main plane of extension. The axis of rotation may be situated essentially parallel or essentially perpendicular to the main plane of extension. The first mass element and the second mass element may be coupled with one another in spring-elastic fashion via a spring system according to the present invention. Alternatively, in particular the first and second mass element can be coupled immovably to one another; in this case, the seismic mass is for example fashioned in one piece. The drive direction may be essentially parallel or perpendicular to the main plane of extension of the substrate. The detection direction may be essentially parallel or essentially perpendicular to the main plane of extension of the substrate. The seismic mass may be driven to a linear oscillation along the drive direction and/or to a rotational oscillation; in the case of a rotational oscillation, an axis of oscillation about which the rotational oscillation takes place is essentially perpendicular to a plane of oscillation, the drive direction being situated in the plane of oscillation. The seismic mass may be excited to a detection oscillation as a function of a Coriolis force, the detection oscillation for example being a linear oscillation along the direction of detection and/or a further rotational oscillation about a further axis of oscillation. For example, the plane of oscillation is essentially parallel to the main plane of extension and the further axis of oscillation is essentially parallel to the plane of oscillation and perpendicular to the axis of rotation.
According to a development, it is provided that the rotational rate sensor has a quadrature offset arrangement, the quadrature offset arrangement being configured to produce a quadrature offset force acting on the second mass element, the quadrature offset force being oriented in a preferred direction essentially opposite and parallel to the compensation direction. In particular, the quadrature offset arrangement is a spring system according to the present invention, an electrode system, and/or a structure of the rotational rate sensor, each of which is/are fashioned such that the quadrature offset force oriented or directed in the preferred direction is produced.
According to a further development, it is provided that the rotational rate sensor has a spring system that is configured to produce the quadrature offset force directed in the preferred direction. In this way, it is advantageously possible to provide, with comparatively simple arrangement, a rotational rate sensor that has exclusively the quadrature offset force acting in the preferred direction, which is superposed on a quadrature force produced by scattering in the production process. In this way, the space requirement can advantageously be reduced and the production costs can be lowered.
According to a further development, it is provided that the first mass element is coupled to the second mass element by a spring element of the spring system, the spring element being pre-tensioned to produce the quadrature offset force directed in the preferred direction. The first mass element may be coupled to the second mass element by a plurality, in particular four, spring elements of the spring system, the plurality, in particular four, spring elements being pre-tensioned in order to produce the quadrature offset force directed in the preferred direction. In this way, it is advantageously possible to produce the quadrature offset force through the realization of the spring elements in a particularly simple and efficient manner.
According to a further development, it is provided that the spring system has a plurality of spring elements that couple the first and second mass element, the plurality of spring elements of the spring system having different spring characteristics, the spring characteristic being in particular a spring structure width, a spring structure height, a spring length, a spring cross-section extending essentially parallel to the drive direction, a spring type, a spring rigidity sensor, and/or a spring material. In this way, it is advantageously possible through a multiplicity of exemplary possibilities to provide exclusively the at least one compensating arrangement configured to produce the compensating force, and/or to configure the rotational rate sensor in such a way that a quadrature offset force acting on the second mass element is directed exclusively in a preferred direction opposite and parallel to the compensation direction.
According to a further development, it is provided that
In this way, it is advantageously possible to produce the quadrature offset force in a particularly simple and efficient manner.
According to a further development, it is provided that the first mass element is formed at least partly from a first functional layer applied on the substrate, and the second mass element is formed at least partly from a second functional layer applied on the first functional layer, the first functional layer and second functional layer being situated one over the other along a direction of projection perpendicular to a main plane of extension of the substrate, the spring element of the spring system being coupled at a first end to the first mass element, the spring element of the spring system being coupled at a second end to the second mass element. In this way, it is advantageously possible, through such a realization of the spring elements, to produce the quadrature offset force in a particularly simple and efficient manner even in a direction of projection essentially perpendicular to the main plane of extension.
According to a further development, it is provided that the spring element has a spring cross-sectional surface extending along a cross-sectional plane, the cross-sectional plane being essentially parallel to the drive direction and essentially parallel to the direction of projection, in particular the spring cross-sectional surface being fashioned asymmetrically relative to a, or each, mirroring axis running along the spring cross-sectional surface, the spring cross-sectional surface being in particular L-shaped, or having an opening extending from an edge into the spring cross-sectional surface, extending essentially parallel to the direction of projection and/or essentially parallel to the drive direction. In this way, it is advantageously possible through such a realization of the spring elements to produce the quadrature offset force in an efficient manner.
According to a further development, it is provided that the at least one compensating arrangement is configured for the compensation of at least the quadrature offset force oriented in the preferred direction by the compensating force oriented in the compensating direction, the compensating force and the quadrature offset force in particular essentially canceling one another. The compensating force may be set as a function of the quadrature offset force, in particular by a closed control and regulation circuit of the rotational rate sensor. In this way, it is advantageously possible to produce the quadrature offset force in a particularly simple and efficient manner.
According to a further development, it is provided that the at least one compensating arrangement is a compensating electrode connected to the substrate, the compensating electrode being configured to produce the compensating force as a function of a quadrature voltage applied between the compensating electrode and the second mass element. In this way, it is advantageously possible to compensate the quadrature using only a single compensating electrode.
Exemplary embodiments of the present invention are shown in the drawings and are explained in more detail in the following description.
In the various Figures, identical parts have always been provided with identical reference characters, and are therefore as a rule named or mentioned only once.
In contrast, both first mass element 21 and also second mass element 22 are capable of being deflected along a direction of detection 101′ that is essentially perpendicular both to drive direction 102′ and to axis of rotation 103′, for example as a function of a Coriolis force acting on first mass element 21 and/or as a function of a quadrature force. For example, first mass element 21 executes a first deflection movement 201 parallel to detection direction 101′, and second mass element 22 executes, in particular due to its coupling to first mass element 21, a second deflection movement 201′ parallel to detection direction 101′. Here, the quadrature force is for example a quadrature force impressed by the production process, which, even if rotational rate sensor 1 is not charged with a rotational rate 104, results in a deflection of first and/or second mass element 21, 22 along detection direction 101′ when first mass element 21 is driven to drive movement 202. The quadrature force here can, for example randomly (due to the production process), be oriented both essentially parallel to detection direction 101′ and also in the opposite direction parallel to detection direction 101′.
According to the present invention, it is advantageous that rotational rate sensor 1 has at least one compensating arrangement 30, the at least one compensating arrangement 30 being configured to produce a compensating force, the compensating force being oriented in a compensation direction 31 essentially parallel to detection direction 101′. In this way, it is advantageously possible for the quadrature force to be capable of being compensated for example by compensating arrangement 30. In the example shown in
The at least one compensating arrangement 30 may be the only compensating arrangement 30 of the rotational rate sensor, the at least one compensating arrangement 30 being configured exclusively to produce the compensating force oriented in compensation direction 31. In particular, at least one single compensating arrangement here means that there can also exist two, three, four, or more compensating arrangement 30 fashioned in the same manner, but however in particular each at least one compensating arrangement 30 is configured only such that in each case a compensating force is exclusively produced that is oriented in compensation direction 31. In addition or alternatively, the statement that the at least one compensating arrangement 30 is configured exclusively to produce the compensating force oriented in compensation direction 31 means that rotational rate sensor 1 has no other compensating arrangement 30′ configured to produce another compensating force in a further compensation direction 31′ opposite and parallel to compensation direction 31.
According to an alternative specific embodiment or a development, rotational rate sensor 1 is configured such that a quadrature offset force acting on second mass element 22 is directed exclusively in a preferred direction 32 opposite and parallel to compensation direction 31. The provision of only the at least one compensating arrangement 30 is for example therefore adequate and preferred according to the present invention, because rotational rate sensor 1 is preset in such a way that, independently of the random direction of the quadrature force, a quadrature offset force is produced that for each sensor is always oriented in a preferred direction 32 that is directed opposite to compensation direction 31. In particular, compensating arrangement 30 is configured for the compensation of an overall quadrature force that is essentially equal to a vector sum of the quadrature offset force and the quadrature force.
According to an alternative specific embodiment or a development, rotational rate sensor 1 has in particular only a single compensating arrangement 30 that is configured to produce a compensation force acting on second mass element 21 and oriented in compensation direction 31.
According to an alternative specific embodiment or a development, rotational rate sensor 1 has in particular a quadrature offset arrangement 40, quadrature offset arrangement 40 being configured to produce a quadrature offset force acting on first and/or second mass element 21, 22, the quadrature offset force being oriented essentially in a preferred direction 32 opposite and parallel to compensation direction 31.
In particular, here compensating arrangement 30 is a compensating electrode that is for example situated in a recess 22′ of second mass element 22 and in particular is connected in stationary fashion to the substrate. Alternatively, compensating arrangement 30 is situated between first and second mass element 21, 22, or outside both first and second mass element 21, 22.
Here, spring system 40 has a plurality of spring elements 41, 41′, 42, 42′ that couple the first and second mass element 21, 22, the spring system here in particular including four spring elements 41, 41′, 42, 42′.
In coupled systems, cf.
For non-coupled systems, as shown for example in
In addition, a spring structural height, a first and second spring length 44, 44′, a spring cross-sectional surface 400′ extending essentially parallel to drive direction 202, a spring type, a spring rigidity sensor, and/or a spring material can also be different.
The rotational rate sensor shown here is also referred to as an omega-Z rotational rate sensor. Because both drive movement 202, 202′ and detection movement 201, 201′ take place parallel to main plane of extension 100, according to the present invention it is advantageously possible to set a defined oblique force, or quadrature offset force, via a slightly asymmetrical realization of the plurality of spring elements 41, 41′, 42, 42′ of spring system 40.
Number | Date | Country | Kind |
---|---|---|---|
10 2013 216 935.3 | Aug 2013 | DE | national |