[Show abstract][Hide abstract] ABSTRACT: We describe an alternating dc track servo pattern as a way to avoid magnetization imbalances within the position error signal (PES) regions of the media in perpendicular recording systems. A spin-stand was used to compare signal amplitude and medium noise between the alternating dc track servo pattern and a conventional dc-track servo pattern. The alternating dc track servo pattern improves the signal amplitude and decreases the residual noise. Therefore, the new servo pattern exhibits a superior signal-to-noise ratio of the PES regions.
No preview · Article · Nov 2005 · IEEE Transactions on Magnetics
[Show abstract][Hide abstract] ABSTRACT: A perpendicular recording system can provide improved writing ability on high-coercivity media and stabilize high-density bits against the superparamagnetic effect. On the other hand, when bits are written on a perpendicular medium at low density, as is the case with the PES (position error signal) region of a conventional servo pattern, linearity in reading/writing operations is distorted, which are strongly affected by the regions of dc magnetization. This paper presents a way in reducing such distortion of characteristics of reading/writing processes using perpendicular media.
[Show abstract][Hide abstract] ABSTRACT: We describe an advanced dc-free track code pattern that uses diphase code for a perpendicular recording. Track code error rates are compared between diphase code, dummy-bit code, and conventional dibit code. The diphase code improves writing ability during servo track writing and maintains equivalent medium noise. Therefore, the diphase code exhibits a superior track code error rate within a wide range of radius on experimental hard disk drives.
No preview · Article · Feb 2005 · IEEE Transactions on Magnetics
[Show abstract][Hide abstract] ABSTRACT: A design methodology for reducing seeking noise in a hard disk drive has been developed. This method can optimize the seeking current according to a shock-response-spectrum analysis. It was verified experimentally that this method can reduce the seeking noise by about 4 dBA on average without increasing the seeking time.
No preview · Article · Sep 2003 · Microsystem Technologies
[Show abstract][Hide abstract] ABSTRACT: A technique for evaluating track deviation in magnetic disk drives
has been developed. The technique uses an external position sensor and
an error cancellation sequence, and enables measurement of
track-to-track spacing. The resolution of track position is less than 2
nm. The repeatability is less than 5 nm. The technique helps reveal
track alignment error, which needs to be reduced to achieve
No preview · Article · Aug 2001 · IEEE Transactions on Magnetics