Device and method for measuring an angular speed

#The present invention concerns an angular speed measuring device comprising:

#a transducer intended to rotate at said angular speed;

#means for generating a mechanical vibration of said transducer in response to an excitation signal, said mechanical vibration comprising a parasite component, and at least one useful component having an amplitude which is representative of said angular speed;

#FIG. 1A shows a longitudinal cross-sectional view of a tuning fork such as that used in certain gyrometers;

#FIG. 1B is a transversal cross-sectional view I--I of the excitation arm (E) and the detection arm (D) of the tuning fork of FIG. 1A;

#FIG. 2 is a schematic view of the angular speed measuring device according to the invention;

#Reference will now be made to FIG. 1. In this figure an example of a tuning fork 1 of the type used in gyrometers has been represented. Tuning fork 1 is represented in a longitudinal cross-section in FIG. 1A comprising principally a base 3 fixedly connected to two arms 5, 7, the assembly being manufactured of a quartz piezoelectric material. As has been represented by a transversal cross-section view according to FIG. 1B, each arm 5, 7 comprises electrodes 9, 11. The excitation arm (E) 5 comprises excitation electrodes 9, only one of the four electrodes represented having been referenced, allowing the application of an electric signal .+-.V which allows to excite, and as a consequence allows to mechanically vibrate the arms 5, 7 of tuning fork 1 in a first plane, as indicated by the arrows 13. The detection arm (D) 7 comprises detection electrodes 11, only one of the four electrodes represented having been referenced, which allow to transform the mechanical vibrations of the detection arm into an electric detected signal.

#According to the theory of tuning fork gyrometers, an angular rotational movement of tuning fork 1 around its longitudinal axis 15 during which an excitation signal is applied to the excitation electrode (E) 9, generates a Coriolis force perpendicular to the excitation, and as a consequence a vibration of at least the detection arm (D) 7 in a plane perpendicular to the plane corresponding to the excitation vibration, as indicated to the arrow 17.

#This mechanical vibration is transformed by the piezoelectric quartz of tuning fork 1 into an electric signal which is detected by the detection electrodes 7 of tuning fork 1.