US Patent 7231312 Physical quantity detecting method and sensor device

A physical quantity is detected by approximating a relationship between an output of a sensor and the physical quantity to be determined by the sensor by setting as coefficients of a quadratic equation a temperature characteristic of non-linearity of the sensor to the physical quantity and temperature characteristics of parameters affecting the output of the sensor. Each of the coefficients is approximated by a higher-order equation with the temperature set as an independent variable, and the temperature coefficient is stored in advance. The temperature coefficient stored in the storage unit and the real-time temperature are substituted into the higher-order equation. The achieved coefficients and the output of the sensor are substituted into the quadratic equation to calculate the actual physical quantity.