Development of three-axis actuator for HD-DVD

There is much research being conducted on developing information storage devices based on formats of Blu-ray Disc (BD) and HD-DVD with requirements for high-density storage devices. This trend is set toward the use of a short-wave length laser and objective lens (OL) with high numerical aperture in optical storage devices. However, it causes the rapid decrease of tilt margin. Therefore, it is necessary that an actuator control tilt motion and have fast access time to get a stable signal. In this paper, a mathematical form of a three-degrees-of-freedom (DOF) coupled model was formulated and magnetic circuit in mechanical constraints was efficiently designed through at trial-and-error method using electromagnetic (EM) analysis. Finally, in order to have fast access time, a three-axis actuator whose rotational center is put on a lens center through redesign of tilting magnetic circuit was suggested. This design targets were evaluated by experiments.