| 摘要 |
PURPOSE:To vary effectively the frequency automatically by expanding/ contracting a piezoelectric substrate with a piezoelectric actuator formed by laminating plural piezoelectric thin film layers. CONSTITUTION:A piezoelectric actuator 12 is formed by laminating plural piezoelectric thin films and interposing alternately a positive electrode and a negative electrode between the films. An interdigital electrode 10 is formed on the front surface of the piezoelectric substrate 8. The thickness of the substrate 8 is sufficiently made thinner than that of the piezoelectric actuator 12. The substrate 8 is fixed on a face in parallel with the piezoelectric actuator 12 in the piezoelectric thin film layer direction. One end of the piezoelectric actuator 12 is fixed to a fixed face 16 of a printed-circuit board or the like via a support 14. The length of the piezoelectric actuator 12 in the piezoelectric thin film laminating direction is changed with an applied voltage given to the piezoelectric actuator 12. Then the length of the substrate 8 is changed to change the frequency characteristic of the surface acoustic wave device. |
