Image Number 18 for United States Patent #5872439.
A motor control device for controlling a swing motor which moves a head is provided with a disturbance observer and an operation suspending unit. The disturbance observer outputs a compensating signal for compensating a driving voltage V for driving the swing motor. The operation suspending unit suspends an operation of the disturbance observer, based on a detection signal supplied by a velocity sensor which detects an angular velocity of the swing motor and the driving voltage signal V for driving the swing motor. The operation suspending unit operates when the signal voltage in the disturbance observer exceeds a reference level. This arrangement solves the following problem arising when the disturbance observer is employed for controlling a motor: when the motor comes into collisions with a stopper at an edge of the motion space, the disturbance observer further drives the motor so as to oppose a motion caused by the collisions, thereby exacerbating the collision.