| 摘要 |
<p>The temperature characteristic of a pressure measuring device using two crystal resonators attributed to the pressure and physical property differences between the resonators can be inexpensively compensated with a high accuracy, by correcting the difference between oscillation frequencies of the resonators using a quadratic formula of the temperature, or by previously relieving the temperature characteristic of the difference in oscillation frequency by connecting a thermister to the oscillation circuit. An oscillation circuit (1) having a crystal resonator placed in a vacuum and another oscillation circuit (2) having another crystal resonator placed under the atmospheric pressure are provided, and the oscillation pulses of the circuits (1) and (2) are counted by counters (3, 4). One of the numbers of pulses counted is subtracted from the other by a subtractor (5), and the subtraction result is outputted to an MPU (6) as a measured value. A temperature sensor (7) measures the ambient temperature of the resonators and outputs the measured temperature to the MPU (6) through an A/D converter (8). The MPU (6) determines a quadratic correcting formula of the temperature from the inputted temperature data and a correction factor stored in a ROM (9) and corrects the measured value based on the formula.</p> |
