Patent ID: 7231312

Claim:
A physical quantity detecting method for detecting an actual physical quantity, the method comprising: approximating a relationship between an output of a sensor and the actual physical quantity to be determined by the sensor by setting as coefficients of a quadratic equation a non-linearity of the sensor itself to the physical quantity and parameters affecting the output of the sensor, wherein the quadratic equation is expressed as: C 1 =A·X 2 +B·X+C 0 wherein C 1 represents an AD-converting value, X represents the actual physical quantity, A represents non-linearity to the physical quantity, and B and C 0 are the parameters affecting the output of the sensor; approximating each of the coefficients by a higher-order equation with the temperature set as an independent variable; storing the temperature coefficient thereof in a storage unit in advance; and on the basis of real-time output of the sensor, executing processing of: substituting the temperature coefficient stored in the storage unit and the real-time temperature into the higher-order equation to determine the non-linearity of the sensor itself to the physical quantity and the parameters affecting the output of the sensor which are the coefficients of the quadratic equation; substituting the thus-achieved coefficients and the output of the sensor into the quadratic equation to calculate the actual physical quantity to be determined to detect the actual physical quantity; and storing the actual physical quantity in the storage unit.