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公开(公告)号：AT166486T
公开(公告)日：1998-06-15
申请号：AT93301584
申请日：1993-03-02
Applicant: IBM
Inventor： HATCHETT MICHAEL ROBERT , HEATH JOHN STEWART , LEE HUBERT CHEW , ROW EUN KYOUNG , SPENCER ROGER DALE , WORKMAN MICHAEL LEE
Abstract: A multiple disk drive assembly (10) in a 5 1/4 inch disk drive form factor having two 3 1/2 inch disk drive form factor head-disk assemblies (HDA) (11, 13) internally mounted on a rigid frame (15) and accessible via a common industry-standard interface connector (55) is provided. Both the interface and power connectors (55 and 53 respectively) and the frame mounting hole patterns are industry standard to provide interchangeability with 5 1/4 inch form factor disk drives provided by manufacturers for use in computer systems. A single electronics controller board (17) is shared by both HDAs and is mounted on the bottom side of the frame below the HDAs. The controller board may implement SCSI or IPI interfaces in either differential or single-ended versions. A spring vibration damper (47) is utilized to minimize external vibration and shock effects on the HDAs and also to minimize the effects of vibration internally generated by one HDA on the adjacent HDA. The assembly is fully enclosed with metal top and bottom covers (19 and 21 respectively) to provide separate enclosures for the HDAs and the controller board cooling and to provide EMC and RFI protection.
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公开(公告)号：SG42810A1
公开(公告)日：1997-10-17
申请号：SG1995002122
申请日：1992-06-23
Applicant: IBM
Abstract: A data storage system using a moving storage medium quickly measures and accurately compensates for thermal and mechanical errors in the position of the data detector with respect to the written data. This is accomplished by measuring the error rate of the written data as a function of the read offset of the detector. Error rates become increasingly large as the sensed noise to signal ratio becomes large. The number of errors detected in reading written data for various read offsets when the data storage system is initially activated is counted. When the number of errors reaches a target rate, the read offset required to produce the target rate is saved. This procedure is performed on either side of the data track. The detector is then centered between the two offsets. During the operation of the storage system, thermal and mechanical errors are introduced into the detector position compensation means. The present invention compensates for this by periodically determining a new offset for each side of the data track. The new offset which corresponds to the target error rate is found by interpolating between measured offsets for error rates which are higher and lower respectively than the target error rate. The new measured read offsets are obtained by reading back written data in a similar manner as was used to obtain the initial read offsets. The detector is then recentered with respect to the write transducer position between the new offsets on either side of the data track.
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公开(公告)号：DE3782448T2
公开(公告)日：1993-05-06
申请号：DE3782448
申请日：1987-04-16
Applicant: IBM
Inventor： WORKMAN MICHAEL LEE
Abstract: A digital servo control system for a data recording disk file receives as input a digital head position error signal (PES) and a digital signal corresponding to the head actuator input signal, and outputs a digital control signal. The control signal is integrated and amplified to provide the input signal to the actuator. The control signal is calculated from estimated values of absolute head position, head velocity and the equivalent actuator input signal required to compensate for constant or very low frequency bias forces. The estimated values are functions of respective predicted values, which in turn are functions of, among other things, constants representing the digital sampling time and physical parameters of the actuator. The updating of the estimated values from the respective predicted values is made with the use of an error term, which is the error between the measured absolute head position and the predicted absolute head position. The predicted absolute head position is made sufficiently accurate, that the error term is always less than a selected number of tracks. This permits the digital servo control system to operate during track seeking without counting track crossings so that the system is operable with servo information recorded either in sectors on a data disk or in continuous tracks on a dedicated servo disk.
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公开(公告)号：DE3670919D1
公开(公告)日：1990-06-07
申请号：DE3670919
申请日：1986-06-06
Applicant: IBM
Inventor： WORKMAN MICHAEL LEE
Abstract: n improvement to a disk file servo control system removes repeatable error from the read write head position error signal (PES) during track following. The disk file includes a microprocessor 60 and associated memory devices 62,64. A table of values of a sine function having a frequency equal to the disk rotational frequency is stored in a memory device. The microprocessor 60 receives each sample of PES from the servo control system and values from the sine function table in the memory device and computes a group of tap weights, each tap weight being a function of the PES sample, the value of a sine or cosine function with a frequency at one of the harmonics of the disk rotational frequency, a learning ratefac- tor and the corresponding value of the tap weight for the previous PES sample. For each PES sample, the tap weights in a group are added to generate a repeatable error correction signal U c which is summed with the control signal U to the head actuator, thereby generating a modified control signal U m which causes the head to follow the true track centerline. The repeatable error components are thus removed from the PES.
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