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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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公开(公告)号：DE68919624D1
公开(公告)日：1995-01-12
申请号：DE68919624
申请日：1989-09-21
Applicant: IBM
Inventor： CHEN JAMES CHIEN-CHIUNG , SHIH SHIH MING , YU MANTLE MAN-HON
Abstract: A disk file digital servo control system utilizes a state estimator wherein the voice coil motor (VCM) (40) current is modeled, rather than measured, thereby eliminating the need for analog-to-digital conversion of the actual VCM current. The VCM current is fed back directly to the input to the power amplifier (42) where it is summed with the control signal output. This effectively changes the integrating power amplifier into a low pass filtering power amplifier, with linear input-output characteristics. Thus, during track following or short seeks, the VCM current is estimated based on this linear model. During long seeks, when the power amplifier is saturated, the VCM current is modeled based upon the known VCM characteristics during saturation, which include the effects of the back electromotive force and the coil current rise time. The microprocessor (50) in the digital servo control system determines which VCM current model to use by a determination of when the power amplifier is in saturation. In the preferred embodiment, the microprocessor determines power amplifier saturation based upon a value of the head velocity error, which is the difference between the commanded velocity and the estimated velocity.
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公开(公告)号：SG82615A1
公开(公告)日：2001-08-21
申请号：SG1999002731
申请日：1999-05-24
Applicant: IBM
Inventor： SERRANO LOUIS JOSEPH , YU MANTLE MAN-HON , BLAUM MARIO , KABELAC WILLIAM JOHN
Abstract: There is disclosed an error correction and detection method and apparatus for retreiving predetermined data, e.g. servo data, from the position error signal (PES) fields of a disk in a data storage system . In the preferred embodiment the PES data such as the track number is mapped into codewords of an error correction code (ECC) which are then further divided into a set of symbols which are mapped onto a second set of bit vectors which have a constant weight. The preferred encoding method is selected to equalize the analog signal characteristics of the PES fields so that minimal, if any, change in the conventional servo detection circuitry needed to use the PES fields of the invention both as analog and digital information.
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公开(公告)号：SG60182A1
公开(公告)日：1999-02-22
申请号：SG1998000065
申请日：1998-01-08
Applicant: IBM
Inventor： SERRANO LOUIS JOSEPH , YU MANTLE MAN-HON
Abstract: In a hard disk drive, a head actuator periodically is caused to undertake a calibration seek such that the power amplifier that energizes the head actuator is saturated. The predicted distance moved by the head during the calibration seek is compared to the actual distance moved, and the ratio of the two distances is then used to determine the saturation current of the power amplifier. For a subsequent seek, if the saturation current is less than the current requested for the subsequent seek, the saturation current is input into the head position prediction model. Otherwise, the requested current is used.
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Patent Agency Ranking
公开(公告)号：DE3855647T2
公开(公告)日：1997-05-07
申请号：DE3855647
申请日：1988-08-16
Applicant: IBM
Inventor： EDEL STEPHEN F , WORKMAN MICHAEL LEE , YAMAMOTO KENNETH GREGORY , YU MANTLE MAN-HON
Abstract: A data recording disk file with a voice coil motor (VCM) actuator (40) and a digital servo control system for positioning the read/write heads (30, 32, 34, 36) to selected concentric data tracks includes means for calculating the factor relating acceleration of the heads (30, 32, 34, 36) to VCM input current. This permits each disk file to compensate for any variation in the nominal VCM physical parameters, thus enabling VCMs to be manufactured to less demanding tolerances. The disk file also calculates a unique acceleration factor for each head position during movement of the heads (30, 32, 34, 36) from one track to another, thereby improving the arrival time of the heads (30, 32, 34, 36) to the target track. During an initialization procedure, the disk file performs a track seek, during which VCM current and head velocity information are acquired and used by the microprocessor (80) in the digital servo control system to calculate a value representing an average actual acceleration factor unique to that disk file. This value, together with predetermined constants representing the characteristic relationship of acceleration factor to head position in a disk file with a nominal VCM, are used by the microprocessor (80) to calculate the actual acceleration factor for each head position during a track seek.
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公开(公告)号：DE69124124D1
公开(公告)日：1997-02-27
申请号：DE69124124
申请日：1991-02-05
Applicant: IBM
Inventor： YU MANTLE MAN-HON
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公开(公告)号：DE3855647D1
公开(公告)日：1996-12-12
申请号：DE3855647
申请日：1988-08-16
Applicant: IBM
Inventor： EDEL STEPHEN F , WORKMAN MICHAEL LEE , YAMAMOTO KENNETH GREGORY , YU MANTLE MAN-HON
Abstract: A data recording disk file with a voice coil motor (VCM) actuator (40) and a digital servo control system for positioning the read/write heads (30, 32, 34, 36) to selected concentric data tracks includes means for calculating the factor relating acceleration of the heads (30, 32, 34, 36) to VCM input current. This permits each disk file to compensate for any variation in the nominal VCM physical parameters, thus enabling VCMs to be manufactured to less demanding tolerances. The disk file also calculates a unique acceleration factor for each head position during movement of the heads (30, 32, 34, 36) from one track to another, thereby improving the arrival time of the heads (30, 32, 34, 36) to the target track. During an initialization procedure, the disk file performs a track seek, during which VCM current and head velocity information are acquired and used by the microprocessor (80) in the digital servo control system to calculate a value representing an average actual acceleration factor unique to that disk file. This value, together with predetermined constants representing the characteristic relationship of acceleration factor to head position in a disk file with a nominal VCM, are used by the microprocessor (80) to calculate the actual acceleration factor for each head position during a track seek.
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公开(公告)号：SG64475A1
公开(公告)日：1999-04-27
申请号：SG1998000379
申请日：1998-02-20
Applicant: IBM
Inventor： SERRANO LOUIS JOSEPH , YU MANTLE MAN-HON
Abstract: A method and apparatus for writing binary servo data into the servo bursts contained on the storage medium of a storage device. The binary servo information may include track identifying information such as a track number, cylinder number, head number, sector number, index and/or SID. A burst includes T time slots, each slot comprising one cycle of the servo burst frequency, and the servo data to be written comprises X bits of binary data. Each one-bit of the servo data is represented as a slot containing a transition, and each zero-bit is represented as an empty or null slot. In this manner, the present invention provides a highly bit-efficient scheme for representing digital servo data. A high quality PES signal is assured by writing the binary servo information in such a manner as to guarantee a threshold number of transitions per burst as required for accurate peak-hold detection. Data is encoded to provide a constant or substantially constant number of positive transitions per burst to allow accurate integration detection. If the amount of real estate consumed by the servo regions is less critical than the reliability of the binary data, robustness may be enhanced by using dibits rather than single transitions to represent the data.
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公开(公告)号：SG55407A1
公开(公告)日：1998-12-21
申请号：SG1997003943
申请日：1997-11-03
Applicant: IBM
Inventor： ROWAN BRYAN SCOTT , YU MANTLE MAN-HON
Abstract: An apparatus and method for reducing spindle power and acoustic noise in a self-commutating brushless d.c. motor for a disk drive adjusts the commutation angle of the motor until a point of optimum power consumption is reached. In a preferred approach implemented during disk drive operation, a direction in which to change the commutation angle is determined such that spindle power consumption is decreased. The commutation angle is the changed in the determined direction until a point of minimum spindle power consumption is identified. In order to determine the correct direction of commutation angle change, the commutation angle is varied in a first direction for so long as the spindle power consumption is decreasing. If varying the commutation angle of the motor in the first direction results in an increase in spindle power consumption, the commutation angle of the motor is varied in a second direction. During drive operation, the commutation angle may be varied back and forth in order to maintain the point of minimum spindle power consumption. The apparatus and method also minimizes torque ripple by determining a drive torque profile and storing that profile in memory as a table of torque constant values indexed to the rotational position of the disk. As the disk spins, its rotational position is sensed and the drive current is adjusted using a corresponding torque constant value. In this way, the drive current is varied inversely to the torque profile so as to produce a substantially uniform torque output, or a torque output that additionally compensates for structural resonance or other drive properties. Still further, a current offset value may be applied that is proportional to the difference between the torque profile and the average torque.
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