TEMPERATURE COMPENSATION SYSTEM FOR PIEZOELECTRIC VIBRATOR TYPE PRESSURE SENSOR

摘要

PURPOSE:To enable highly accurate detection by selecting two frequency- pressure characteristics which are based upon temperature as a parameter and closest to temperature data from plural tables for frequency-pressure characteristics and finding pressure values corresponding to an oscillation frequency relative signal from them respectively, and calculating a pressure value from a signal and both the pressure values. CONSTITUTION:Tens of temperature points are measured, and several point frequency-pressure characteristics are measured as to one temperature table and stored in a ROM 9. Frequency dividing circuits 3 and 4 divide the frequencies of data from a pressure sensor 1 and a temperature sensor 2, the signal of a reference clock 7 is counted 6 in their half-cycle periods, and data is passed to a CPU 8, which retrieves between which tables in the ROM 9 the temperature data is and then retrieves in which table and between which storage points the pressure data is. Proportional calculation is carried out with the respective tables and proportional calculation between the both is also performed to calculate a pressure value. Consequently, the highly accurate detection becomes possible.