DUAL-MODE THICKNESS-SHEAR QUARTZ PRESSURE SENSORS FOR HIGH PRESSURE AND HIGH TEMPERATURE APPLICATIONS

摘要

A dual-mode thickness-shear quartz pressure transducer includes a unitary piezoelectric crystal resonator and cylindrical housing structure wherein the resonator is located on a median radial plane of the housing and the exterior of the housing is provided with a pair of parallel flat surfaces which are located at an angle relative to the X' axis of the resonator. Preferably, the transducer is made from an SC-cut of a WAD-cut solid quartz crystal cylinder. The wall thickness of the cylinder is altered at the location of the flats such that stresses at the center of the resonator disk are anisotropic. The ratio of the stresses at the center of the resonator disk along the X' and Z' axes may be optimized such that the pressure sensitivity of the third thickness harmonic of C mode vibration is maximized, in particular by altering the (azimuthal) angle of the flats. Preferably, the flats are located at an azimuthal angle of approximately 134° relative to the X' axis of a WAD-cut resonator.