TECHNICAL FIELD

The present disclosure relates to an angular velocity sensor and a sensor element used in the angular velocity sensor.

BACKGROUND ART

Known in the art (for example Patent Literature 1) is a so-called piezoelectric vibration type angular velocity sensor. In this sensor, an AC voltage is supplied to a piezoelectric body to excite the piezoelectric body. When this excited piezoelectric body is rotated, a Coriolis force having a magnitude in accordance with the rotation speed (angular velocity) is generated in a direction perpendicular to the direction of excitation. The piezoelectric body vibrates by this Coriolis force. Further, by detecting an electrical signal generated in accordance with the deformation of the piezoelectric body due to the Coriolis force, the angular velocity of the piezoelectric body can be detected.

CITATIONS LIST

Patent Literature

Patent Literature 1: Japanese Patent Publication No. 2005-037235

SUMMARY OF INVENTION

An angular velocity sensor according to one aspect of the present disclosure includes a piezoelectric body, a driving circuit which supplies a voltage to the piezoelectric body, and a detecting circuit which detects a signal generated in the piezoelectric body. The piezoelectric body includes a pair of support parts, a frame, a pair of driving arms, and a detecting arm. The pair of support parts are separated from each other in an x-axis direction in an orthogonal coordinate system xyz. The frame includes a main part and a pair of extension parts. The main part extends along the x-axis. The pair of extension parts, when viewed in a z-axis direction, connect two ends of the main part and inner sides of the pair of support parts and include at least parts which extend in directions intersecting the x-axis. The pair of driving arms extend from the main part alongside each other in a y-axis direction at positions separated from each other in the x-axis direction. The detecting arm extends from the main part in the y-axis direction at a position which is between the pair of driving arms in the x-axis direction. The driving circuit supplies to the pair of driving arms voltages with inverse phases from each other making the pair of driving arms vibrate so as to bend to inverse sides from each other in the x-axis direction. The detecting circuit detects the signal generated due to bending deformation of the detecting arm in the z-axis direction or x-axis direction.

A sensor element according to one aspect of the present disclosure includes a piezoelectric body and includes a plurality of excitation electrodes, a plurality of detecting electrodes, and a plurality of wirings all arranged at the piezoelectric body. The piezoelectric body includes a pair of support parts, a frame, a pair of driving arms, and a detecting arm. The pair of support parts are separated from each other in an x-axis direction in an orthogonal coordinate system xyz. The frame includes a main part and a pair of extension parts. The main part extends along the x-axis. The pair of extension parts, when viewed in the z-axis direction, connect two ends of the main part and inner sides of the pair of support parts and include at least parts which extend in directions intersecting the x-axis. The pair of driving arms extend from the main part alongside each other in a y-axis direction at positions separated from each other in the x-axis direction. The pair of detecting arm extends from the main part in the y-axis direction at position which is between the pair of driving arms in the x-axis direction. The plurality of excitation electrodes are provided in an arrangement enabling application of voltages exciting the pair of driving arms in the x-axis direction. The plurality of detecting electrodes are provided in an arrangement enabling detection of signals generated by vibration of the detecting arms in the x-axis direction or z-axis direction. The plurality of wirings connect the plurality of excitation electrodes in connection relationships whereby phases which are inverse from each other making the pair of driving arms vibrate so as to bend to inverse sides from each other in the x-axis direction are supplied from the plurality of excitation electrodes to the pair of driving arms.

