ROTATION ANGLE DETERMINING APPARATUS

A rotation angle determining apparatus comprises an angle determining means that has determining circuits each including a determining element part consisting of a coil and a resistor and that also has an inductance changing means that changes the inductance of the coil in accordance with the rotation of a rotating object to be determined. The rotation angle determining apparatus further comprises a reference pulse voltage generating means (101) that causes the determining circuits (110,120) to generate output signals; and a calculating means that calculates the output signals of the determining circuits. In this rotation angle determining apparatus, a reference pulse voltage generated by the reference pulse voltage generating means is compared with the output voltages of the determining circuits developed when the reference pulse voltage is inputted to the determining circuits. The result of this comparison is used to calculate a rotation angle of the rotating object, thereby achieving a high degree of determination accuracy over a wide range of rotation angles even in an environment of dynamically changing temperature in spite of a reduced number of components constituting the rotation angle determining apparatus.