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公开(公告)号：GB2344438B
公开(公告)日：2003-04-16
申请号：GB9928233
申请日：1999-12-01
Applicant: IBM
Inventor： LU WEI-MIN , WOOD ROGER WILLIAM , YU MANTLE MAN-HON
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.
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公开(公告)号：GB2344438A
公开(公告)日：2000-06-07
申请号：GB9928233
申请日：1999-12-01
Applicant: IBM
Inventor： LU WEI-MIN , WOOD ROGER WILLIAM , YU MANTLE MAN-HON
Abstract: In a hard disk drive servo control system 300, a digital signal processor (DSP) 310 provides a control signal 322 for controlling a voice coil motor (VCM), which is driven by a D/A converter (DAC) 312. Quantization noise (or roundoff errors) are present due to the finite precision of the DAC driving the VCM, and these contribute to the total track misregistration (TMR). The control signal 322 from the processor 310 has a precision defined by a predetermined number of bits comprising a first group of most significant bits 320 and at least one least significant bit 324. The control error due to quantization noise is reduced by accumulating at least one least significant bit, using a quantization error feedback circuit (figure 6), until a new most significant bit is generated. Then the newly generated most significant bit is added to the existing most significant bits 320 of the control signal to generate a corrected control signal. This results in a reduction in TMR by reducing the control error in the control signal provided by the processor 310.
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