Patent ID: 7659713

Claim:
A method for initializing a rotational angle detector for detecting rotational angles of two driven gears mated with a drive gear, which rotates integrally with a detection subject, and obtaining rotational angle of the detection subject from the detected rotational angles, the method comprising the steps of: obtaining a first error generated in each rotational angle of the two driven gears due to backlash between the drive gear and the two driven gears when the drive gear is rotated in a forward direction; obtaining a second error generated in each rotational angle of the two driven gears due to backlash between the drive gear and the two driven gears when the drive gear is rotated in a reverse direction; obtaining an average value of the first error and the second error; obtaining a difference between the average value and an error-free theoretical rotational angle for each of the two driven gears when the rotational angle of the drive gear is 0°; and storing the difference as correction data added to each actually detected rotational angle of the two driven gears when obtaining the rotational angle of the detection subject.