The present invention relates to a yaw-rate sensor.
Yaw-rate sensors in which a first and a second Coriolis element are arranged on the surface of a substrate are referred to in U.S. Pat. No. 5,728,936. The Coriolis elements are induced to oscillate in a first axis. The deflections of the Coriolis elements due to a Coriolis force in a second axis, which is parallel to the substrate, are verified.
In contrast, the yaw-rate sensor according to the present invention may provide that the Coriolis forces and forces which occur due to an angular acceleration of the substrate have different directions. The exemplary yaw-rate sensor according to the present invention is therefore largely insensitive with respect to angular accelerations.
If the gravitational centers of the Coriolis elements move perpendicular to a straight connecting line between the gravitational centers, then on average over time, the deflections of the Coriolis elements due to the Coriolis force lie on one and the same axis, in which an angular acceleration exerts no force component whatsoever. The Coriolis elements are induced to oscillate particularly easily by a drive element which transmits driving forces through springs. In this case, the Coriolis element may be suspended completely on this drive element. Electrostatic comb drives may be provided on the drive elements as excitation arrangements. The Coriolis force may be verified in that the Coriolis element includes movable electrodes which are arranged opposite stationary electrodes. However, verification elements may also be provided to which the Coriolis forces are transmitted by springs. In this case, the verification elements may be suspended in such a manner on the substrate that only a movement in the direction of the Coriolis forces occurs. Interference effects due to a movement of the movable electrodes which are not in the verification direction are thereby suppressed. To ensure an antiphase oscillation of the Coriolis elements, the antiphase oscillation should be clearly differentiated from the in-phase oscillation in terms of frequency. To that end, coupling springs may be provided between drive elements and/or Coriolis elements, or between drive elements and verification elements.
Exemplary embodiments of the present invention are shown in the drawings and are explained in the following description.