Yasumasa Kuroba

Hard disk drive servo technology for media-level servo track writing

Hard disk drive (HDD) servo technology for media-level servo track writing (MLSTW) is developed. MLSTW is the process of writing servo signals on magnetic disks before they are assembled in drives. It supplies a solution to achieve low-cost and accurate means of servo-signal writing. The HDD servo controller for MLSTW drives compensates for radial and rotational distortions of the servo signals (e.g., track-address, eccentricities, and servo-signal timing) that are inherent in the MLSTW method. The authors prove that the positioning accuracy is improved and the seek time is unchanged by using the new servo controller for HDDs with MLSTW disks.

High-speed orthogonal power effect actuator for recording at over 10000 TPI

A new type of rotary actuator for HDDs is presented. To suppress the resonance gain in the quasi-rigid body mode caused by the stiffness of support bearings, we propose orthogonal driving. The designed actuator for a 3.5-inch drive shows a quasi-rigid body mode gain of less than 5 dB, and a fundamental resonance frequency of approximately 10 kHz. The results agree with those from finite element analysis.

A study of head-disk interface shock resistance

We observed slider and suspension behavior under external shock using a still camera with a stroboscope. This paper shows experimental results of the relationship between disk failure and using Hertzs contact stress formula with energy conservation. We describe a technique to improve shock durability based on this relationship.

Low-profile spindle motor for 5-mm-height PCMCIA disk drive

We developed a new spindle motor with a unique structure for PCMCIA Type-II magnetic disk drives. The motor has extremely small dimensions and has to be highly efficient. The magnetic circuit has radial gaps, axial cores, and a pole-anisotropic ring magnet. We found that the core material and the joints of the core and yoke strongly influenced the motor efficiency and the torque constant. We achieved a motor efficiency 5 times greater than the conventional axial gap motor.