Method and apparatus for detecting defects in piezoelectric actuators
US6556028B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | May 7, 2001 |
| Grant date | Apr 29, 2003 |
| Priority date | — |
| Expiry date | May 7, 2021 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R29/22
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Roughly described, piezoelectric actuators are tested as part of an assembly using a three-stage process. In the first stage, a substantially steady state electromechanical potential is induced into a piezoelectric member of an assembly. Typically this can be accomplished by applying a DC voltage across the crystal for long enough period of time for it to achieve a substantially steady state mechanical distortion. In the second stage, the electromechanical potential of the piezoelectric actuator is discharged rapidly but incompletely. The third stage begins with the abrupt termination of the rapid-discharge stage, thereby causing the crystal, and the voltage produced across it, to oscillate and decay freely. The voltage across the crystal continues to decay slowly in the third stage, and the oscillations continue to decay in magnitude as well, providing a relatively complex signal from which features can be extracted and compared to those of known-good devices.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.