| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an oscillator which is capable of surely detecting the deposition of minute substance or a viscosity change of liquid by enabling the oscillator to be oscillated, in a main oscillation mode having a fixed frequency and amplitude at all times, even if a power supply voltage or an ambient temperature is changed. <P>SOLUTION: The oscillator a substrate 11, a ground electrode 13 formed on a thin portion 12 of the substrate 11, a piezoelectric layer 14, formed on the ground electrode 13, and a drive electrode 15 and a detection electrode 16 formed on the piezoelectric layer 14. The drive electrode 15 is positioned approximately in the center of the thin portion 12 of the substrate 11, and the detection electrode 16 is positioned concentrically with the drive electrode 15. Furthermore, the length (r) from the center of the drive electrode 15 to its outer circumference and the width (w) of the detection electrode 16 are set, in such a manner that between charges, generated by a main oscillation mode and generated by an unwanted oscillation mode, to be generated in a portion of the piezoelectric layer 14, the charge generated by the unwanted oscillation mode can be canceled inside the detection electrode 16. <P>COPYRIGHT: (C)2010,JPO&INPIT |
