| 摘要 |
PURPOSE:To obtain an oxcillation circuit suited for highly accurate time standard by electrically serially connecting two piezoelectric vibrators whose frequency- temperature characteristics are approximately quadratic curves and the codes of the secondary temperature coefficients thereof are opposite. CONSTITUTION:The oscillation circuit is formed by electrically serially connecting a tuning fork type flexural crystal vibrator 5 having the frequency-temperature characteristics showing a quadratic curve 2 being convex upward and a lithium tantalate tuning fork type vibrator 6 showing a quadratic curve 3 being convex downward. Further the zero temperature coefficient temperatures of the respective vibrators are made within a range from 15 to 30 deg.C and the differences therebetween is made less than 5 deg.C. If the secondary temperature coefficient are let to be beta1, beta2 respectively and equivalent capacities to be C11, C12, then ¦beta2¦/¦beta1 C12/C11 is satisfied so as to have flat characteristics like a curve 4. Because of this, the fluctuations of frequencies with respect to temperature changes may be reduced and the reliability such as of electronic wristwatches, etc. may be improved. |
