The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Nov. 12, 2002
Filed:
Dec. 22, 2000
Murata Manufacturing Co., Ltd., Kyoto, JP;
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.