Release: September 21, 2005
NGK INSULATORS, LTD. (President & CEO: Shun Matsushita; Head Office: Nagoya, Japan) developed, by applying its original micro-ceramics technology, a piezoelectric microactuator which improves the positioning accuracy of magnetic heads for hard disk drives (HDD). The company has succeeded in commercializing a slider driving-type piezoelectric microactuator for the first time in the world.
GK has already started the volume production of its microactuators to supply them to magnetic head manufacturers. They are intended to be used in half-terabyte (500GB) HDDs (industry-leading capacity), which are scheduled to be launched by a major US HDD manufacturer. NGK aims to achieve more than 5 billion yen in sales in the fiscal year 2006 (April 1, 2006 -March 31, 2007).
One of the ways to improve HDD areal density is to reduce the track pitch (the distance between adjacent tracks on disks) to increase track density. However when the track pitch is reduced, the accuracy of read/write head positioning is adversely affected by vibrations of disks and spindles and by external and internal disturbances. Until now, there has been no effective method to solve this problem.
The existing HDD systems control the head positioning only by coarse actuators called voice coil motors that are placed at the end of the suspension which holds magnetic heads. When the track density is increased, however, the head positioning by coarse actuators causes defects in responsibility and accuracy. Accordingly, it has been expected to develop dual-stage actuators that incorporate an additional actuator called a piggyback actuator, which enables more precise and quick control of the head positioning. The dual-stage actuator moves the suspension to place a magnetic head at an approximate area by a coarse actuator and moves the head to a precise point by a piggyback actuator. Although various methods and technologies have been examined to commercialize piggyback actuators, none of them has succeeded.
NGK's piezoelectric microactuator is a slider driving-type actuator mounted between the slider and suspension. It can move the slider by a few micrometers at high velocities in the parallel direction and when using a certain driving method, in the rotational direction as well. This piezoelectric microactuator consists of, by applying NGK's original micro-ceramics technology, a thin zirconia substrate and piezoelectric membrane. In addition to superior shock resistance and the capability to operate at low voltage, this microactuator features a long stroke and, at the same time, high responsibility; and thus achieving extremely high accuracy in the head positioning. With its capability to control the head positioning in a long range at high velocities, it can also effectively cancel disturbances caused by external vibrations.
Drawing of a piezoelectric microactuator for HDD heads
Piezoelectric microactuators for HDD heads