System for sustaining and monitoring the oscillation of piezoelectric elements exposed to energy-absorptive media
US4783987A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 10, 1987 |
| Grant date | Nov 15, 1988 |
| Priority date | — |
| Expiry date | Feb 10, 2007 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2291/0256
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
The disclosed system includes a piezoelectric crystal exposed to an energy-absorptive medium of interest. A crystal oscillation circuit is included for sustaining oscillation of the crystal in contact with the fluid. To accomplish this, the circuit includes feedback elements for providing automatic gain control of the amplifier portion of the oscillator. In this manner, the conditions required for crystal oscillation are maintained independent of variations in the medium the crystal is exposed to. Information regarding the gain adjustment and oscillation frequency of the crystal are applied to a microprocessor-based system for determining fluid characteristics such as viscosity, density, and dielectric constant. Alternatively, this information is used to correct for the influence of such parameters on the resonant behavior of piezoelectric crystals undergoing mass change, in the analysis of, for example, corrosion, adsorption and electroplating. The relationship between the particular characteristics determined and the output information received from the oscillation circuit is dependent upon the hydrodynamic and electrokinetic coupling experienced between the medium and crystal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.