| 摘要 |
<p>A hard disc device of this invention has servo burst signals for determining the position of the head recorded at two places on the circumference of each of the tracks in order to improve the recording density. A two-phase stepping motor is finely moved by the servo burst signals through micro stepping to determine its position. The stepping motor is coupled to a rotary actuator via a steel belt to move the head in the radial direction with respect to the disc. The stepping motor is excited for every π/4 (rad) at a two-phase electric angle starting from the position of π/8 (rad) and is excited more finely during the acceleration and deceleration. During the start of the device, hysteresis of the stepping motor is measured and so is the offset value of the stepping motor drive system. These values are corrected while the device is in operation.</p> |
