Patent ID: 7637347

Claim:
An electric power steering apparatus for calculating a steering angle of a steering wheel, the apparatus comprising: a steering shaft connected to a steering wheel of a vehicle; an electric motor for supplying auxiliary steering power to rotate the steering shaft; a direction sensor for detecting a rotational direction of the steering shaft, the direction sensor including a light emitting unit and a light receiving unit which face each other; a rotary member coupled to the steering shaft and rotating as the steering shaft rotates, the rotating member being interposed between the light emitting unit and the light receiving unit and having at least one slot configured to detect the rotational direction of the steering shaft as the steering shaft rotates, the rotary member rotating less than 180 degrees with respect to an entire rotation range of the steering shaft; a motor position sensor coupled to the electric motor for detecting a rotation angle of a rotation shaft of the electric motor; and a control unit receiving electric signals from the direction sensor and the motor position sensor to calculate a steering angle of the steering wheel based on the rotational direction of the steering shaft and the rotation angle of the rotation shaft of the electric motor.