| 摘要 |
<P>PROBLEM TO BE SOLVED: To accurately measure a dielectric constant of a piezoelectric actuator. Ž<P>SOLUTION: The piezoelectric actuator 12 includes first and second driving electrode patterns 41, 42 and a constant potential electrode pattern 43 prepared on respective surfaces of piezoelectric layers 12a and 12b. The constant potential electrode pattern 43 includes measurement electrode parts 43a, 43b and 43c which extend in parallel with intervals provided to measurement electrode parts 41a and 42a of the driving electrode patterns 41 and 42 when seen from a direction Z in which a cavity unit 11 and the piezoelectric actuator 12 stack. The interval h1 between the measurement electrode part 41a and the measurement electrode parts 43a, 43b and 43c, and the interval h2 between the measurement electrode part 42a and the measurement electrode parts 43a, 43b, and 43c are different in size. Each capacitance in an in-plane direction is measured for a plurality of piezoelectric layers by the constant potential electrode pattern 43 and driving electrode patterns 41 and 42. The dielectric constant is obtained on the basis of the measured both capacitances. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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