公开(公告)号：JP2000113612A

公开(公告)日：2000-04-21

申请号：JP26475099

申请日：1999-09-20

Applicant: IBM

Inventor： FAN FU IN ,  WAYNE ISAMI IMAINO ,  ROO JAN CHAN ,  ROGER WILLIAM WOOD

IPC: G11B21/02 ,  G11B5/48 ,  G11B5/55

Abstract: PROBLEM TO BE SOLVED: To reduce a vibration mode and enhance performance and stability by a method wherein there are formed an outside coil and a concentric inside coil in a backward extension part, and at the time of selection, a current of the inside coil is in a counter direction to a current of the outside coil during setting operation and tracking operation, and a current of the outside coil and the inside coil is in the same direction during seek operation. SOLUTION: A double coil actuator assembly 100 has outside and inside actuator coils 102, 104 between actuator coil support arms 94, 96 backwardly of a main body 92. Currents IO, II of the coils 102, 104 during seek operation are in the same direction, and a magnetic field generated by the currents IO, II generates a large synthetic torque by an interaction with the magnetic field of a VCM magnet. In the case of setting operation and tracking operation, the currents IO, II is in a counter direction to each other, and by the interaction with the VCM magnet, an excitation of a vibration mode due to a force generated by the coils 102, 104 is cancelled.

公开(公告)号：SG94720A1

公开(公告)日：2003-03-18

申请号：SG1999004664

申请日：1999-09-17

Applicant: IBM

Inventor： FU-YING HUANG ,  WAYNE ISAMI IMAINO ,  JIANN-CHANG LO ,  ROGER WILLIAM WOOD

IPC: G11B21/02 ,  G11B5/48 ,  G11B5/55 ,  G11B5/54 ,  G11B33/12 ,  G11B21/08

Abstract: An actuator assembly having two coils disposed between the poles of a voice coil motor (VCM) magnet for improved dynamic performance during settling and tracking operations in a disk drive. The two coils in the VCM are connected to separate current sources to allow the current flow in the two coils to have the same sense (clockwise or counterclockwise) or the opposite sense with respect to each other. When the current flows in the two coils have the opposite sense, excitation of the principal in-plane bending mode resonance of the actuator assembly is suppressed allowing the use of an increased servo bandwidth for settling and tracking operations of the disk drive. During seek operations of the disk drive, where maximum torque on the actuator is desirable, the coil currents in the two coils are chosen to have the same sense so that the forces on the actuator from the two coils are additive.

公开(公告)号：SG86361A1

公开(公告)日：2002-02-19

申请号：SG1999005862

申请日：1999-11-22

Applicant: IBM

Inventor： WEI-MIN LU ,  ROGER WILLIAM WOOD ,  MANTLE MAN-HON YU

IPC: G11B20/00 ,  G05B19/29 ,  G11B33/00

Abstract: A method and apparatus for reducing track misregistration due to digital-to-analog converter quantization noise. In hard disk drive (HDD) servo control systems, quantization noises (or roundoff errors) due to the finite precision of the D/A converter (DAC) driving the VCM contribute a significant portion of the total track-misregistration (TMR). The present invention provides a quantization error feedback (QEF) technique to reduce TMR due to DAC quantization noises. The QEF technique according to the present invention offers a simple method of reshaping the spectrum of this noise to minimize its contribution to TMR. In the digital signal processor (DSP) implementation of the QEF schemes, the quantization error is monitored and accumulated in the DSP; when sufficient error has accumulated, the MSB feeding the DAC are modified such as to cancel the effect of the error. In addition, or alternatively, a state estimator may be driven with the most significant bits and a position error signal to reduce the power spectrum density function of the track misregistration at predetermined frequencies.