| 摘要 |
A crystal oscillator for generating an output oscillation whose frequency is maintained constant independently of the variation of temperature including a first quartz vibrator arranged in a heating unit which includes a thermostat and vibrating at a fundamental frequency, a second quartz vibrator arranged also in the same heating unit and vibrating at a third overtone frequency, a frequency multiplying circuit for multiplying the fundamental frequency by three, a frequency comparator for comparing the fundamental frequency multiplied by three with the third overtone frequency to derive a frequency difference which represents a temperature of the thermostat, and a temperature controlling circuit for controlling the temperature setting of the thermostat in accordance with the detected frequency difference. Any one or both of the fundamental and third overtone oscillations may be derived as an output oscillation. The first and second quartz vibrators are constructed by a single common quartz substrate, a first pair of electrodes each applied on respective main surfaces of the quartz substrate, and a second pair of electrodes each applied on respective main surfaces of the quartz substrate.
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