Dual-mode thickness-shear quartz pressure sensors for high pressure and high temperature applications
US6111340A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 12, 1999 |
| Grant date | Aug 29, 2000 |
| Priority date | — |
| Expiry date | Apr 12, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01L9/0022
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
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. According to the presently preferred embodiment, the transducer is made from an SC-cut or a WAD-cut solid quartz crystal cylinder which is ultrasonically milled to form a plano-convex or bi-convex resonator disk in the medial radial plane of a hollow cylinder and the pair of exterior flats. 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. According to the invention, the ratio of the stresses at the center of the resonator disk along the X" and Z" axes are optimized such that the pressure sensitivity of the third thickness harmonic of C mode vibration is maximized. Optimization of the ratio of the stresses along the X" and Z" axes is accomplished in particular by altering the (azimuthal) angle of the flats. According to a pres…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.