| 摘要 |
PURPOSE:To obtain excellent frequency-temperature characteristics by decreasing remarkably the absolute value of the sum of the primary temperature coefficient of the Young's modulus of a ceramic vibrator and its primary linear expansion coefficient. CONSTITUTION:Ceramic tuning fork 1 with piezoelectric thin film 2 formed on its surface is supported at its base part by lead wires 3 and 4 as electrode terminals. Denoting the primary temperature coefficient of the Young's modulus of a material for vibrator 1 by E1 and its primary linear expansion coefficient by X1, a frequency variation ratio is unrelated with a temperature with E1+X1=0, namely, when E1 and X1 are opposite in sign and equal in absolute value. By selecting the adequate composition of the material, X1 of (4.0-9.2)X10<-6>/ deg.C and E1 of (-11.2-2.0)X 10<-6>/ deg.C can be obtained, and therefore ¦E1+X1¦ can be reduced below a value of 2X10<-6>. Consequently, frequency variation ratio DELTAf/f is expressed by (I) [wherein t represents the temperature] and excellent frequency-temperature characteristics can be obtained. |
