Method of inspecting piezoelectric ceramic device
US6480010B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 22, 2000 |
| Grant date | Nov 12, 2002 |
| Priority date | — |
| Expiry date | Dec 22, 2020 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N33/388
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A piezoelectric ceramic device is heated so that the temperature is increased to a temperature in the vicinity of the maximum temperature at which the device, when the temperature is returned to ordinary temperature, is returned to substantially the same piezoelectric characteristic before heating. In the state that the piezoelectric ceramic device is heated, and the temperature is increased, at least one of the piezoelectric phase characteristic and the impedance characteristic of the piezoelectric ceramic device is measured. The measurement is compared with a standard characteristic, whereby an internal defect of the piezoelectric ceramic device is detected, based on results of the comparison. For the heating and temperature-increasing, and the measuring, a high frequency measurement signal having a power level that is higher than the rated level of the piezoelectric ceramic device is applied, and simultaneously with the piezoelectric ceramic device itself being dielectric-heated by the application of the high frequency signal, at least one of the piezoelectric phase characteristic and the impedance characteristic is measured.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.