| 摘要 |
PURPOSE:To omit the replacing work of an ultrasonic wave head every time the frequency is changed, by using the ultrasonic wave head, in which a plurality of piezoelectric elements are arranged in a concentric disk shape, so that a plurality of ultrasonic waves having different frequencies can be generated by one head. CONSTITUTION:A common lower electrode 12 is formed on one end surface 11a of an acoustic lens 11 comprising sapphire by evaporation. Another end surface 11b of the acoustic lens 11 has a concave spherical surface so as to have a lens action. Piezoelectric elements 13 and 14 comprising a piezoelectric material are provided in a concentric circle state on the lower electrode 12. Upper electrodes 15 and 16 are formed on the piezoelectric elements 13 and 14. The lower electrode 12 and the upper electrode 15 are directly connected to a signal source 17, and, e.g., an ultrasonic wave of 400MHz is generated. The upper electrode 16 can be selectively connected to the upper electrode 15 through a switch 18. Thus, e.g., an ultrasonic wave of 100MHz is generated. In this constitution, frequency can be changed without replacing an ultrasonic wave head. |
