Abstract: A current driver for supplying write current to an inductive write head of a disk drive includes an H-switch and first and second damping circuits connected across the inductive head. Each damping circuit includes a first controlled resistor (such as a MOS transistor) connected across the head. A delay circuit is connected between a load terminal at one side of the head and the control terminal of the MOS transistor, and is responsive to a transient voltage at the load terminal to delay the transient voltage to the control terminal of the MOS transistor for a predetermined delay period. The MOS transistor is responsive to the delayed transient voltage to provide a predetermined electrical resistance across the head to dampen undershoot and ringing in the driver. The MOS transistor turns off when the voltage at the load terminals stabilizes, thereby removing the damping resistance from the circuit.

Abstract: A method and system for detecting common mode disturbances from a magnetic recording head having dual magnetic recording elements. An electrical current is supplied to both of the dual magnetic recording elements within the magnetic recording head. Thereafter, the electrical current is shunted through only one of the dual magnetic recording elements. A voltage signal is then detected across the dual magnetic recording elements, which occurs in response to the shunting of the electrical current through only one of the dual magnetic recording elements. Finally, the voltage signal is analyzed for indications of common mode disturbances accentuated as a result of the shunting of the electrical current through only one of the dual magnetic recording elements. Common mode disturbances that can be detected include thermal asperities.

Abstract: A read head of a head device used in a disk storage apparatus is provided including a spin-valve magnetoresistive (MR) element. The spin-valve MR element comprises a pinning magnetic layer of which magnetizing direction is determined, a free magnetic layer of which magnetizing direction can be shifted by a signal magnetic field derived from the disk, and a non-magnetic layer sandwiched between the pinning magnetic layer and the free magnetic layer. The head also includes a remagnetization layer which functions as a control element for correcting the magnetizing direction of the pinning magnetic layer.

Abstract: A digital servo track pattern for a magnetic medium which can be recorded and reproduced by a recording and reproducing system. The servo track pattern has a plurality of digital mark patterns recorded thereon, each of said digital mark patterns having a leading identifier field of digital bits, a trailing identifier field of digital bits and a field of digital synchronizing data located between said leading and trailing identifier fields. The leading identifier field of digital bits is electrically equivalent during reproducing while the medium is moving in a first direction to the trailing identifier field of digital bits while the medium is moving in a direction opposite to said first direction.

Abstract: A timing-based servo system for positioning a magnetic head relative to a magnetic storage medium, the magnetic storage medium having a servo pattern written thereon, the system comprising a head including a servo read element configured to read the servo pattern and produce a signal, the signal including recognizable signal events corresponding to the servo read element reading servo transitions; a servo decoder configured to receive the servo signal, determine the position of the head, with respect to the servo band, in response to the amount of time between the signal events, and generate an error signal indicative of actual head position relative to desired head position with respect to the servo band, the servo decoder including time capture logic configured to determine the amount of time between the signal events, the time capture logic including a multiple phase clock generator.

Abstract: A program is selected from a plurality of programs in an MPEG transport stream for recording on a record carrier. The presence of a program clock reference (PCR) value in a packet in the stream is detected. The packet identifier for the packet is retrieved and stored. Clock reference signals of subsequent packets with a packet identifier equal to the stored packet identifier, are retrieved. The program clock references are used to synchronize a clock counter. Each recorded packet is time stamped according to the clock counter. If clock reference signal is not received within 100 ms, then a packet with a PCR value with a different packet identifier is retrieved and the stored packet identified is replaced by the different packet identifier.

Abstract: A sector address recognition part recognizes a sector address in a magnetic disk where ID areas for storing sector address information and head address information are omitted. This is accomplished by generating a sector pulse when a predetermined count is reached after a detection of a servo mark and when an interval between adjacent servo marks included in servo information that also includes cylinder address information is a preset interval. A head identifier recognition part recognizes a head identifier on the basis of, for example, positions at which the servo information is recorded.

Abstract: A digital magnetic reproducing apparatus comprises a reproducing head to reproduce data from a magnetic recording medium; an equalizer for shaping, by a partial response method, the waveform of the reproduced signal outputted from the reproducing head; and a decoder for decoding, by a maximum likelihood decoding method, the equalized reproduced signal obtained from the equalizer. The reproducing head employed in this apparatus is an MR (magnetoresistance effect) head which is capable of reducing the second harmonic distortion of the reproduced signal to be -25 dB or lower. Therefore the deterioration of the bit error rate that may result from the nonlinear distortion of the MR head can be further lowered within a sufficiently suppressed range in practical use.

Abstract: Disclosed is a method of demodulating a position signal in a magnetic disk device for reading servo burst signals, which have been recorded in a servo area of a magnetic disk, by a head, and outputting a position signal, which indicates a deviation from a reference position on a track, using the servo burst signals that have been read.

Abstract: An adaptive media speed drive unit for use with a magnetic storage medium, the magnetic storage medium having a timing based servo pattern written thereon, the servo pattern including transitions, the drive unit including a magnetic head including a servo read element configured to read the servo pattern and produce a signal, the signal including recognizable signal events corresponding to the servo read element reading servo transitions; a servo decoder including time capture logic configured to determine the amount of time between the signal events; and a digitally controlled oscillator configured to produce a tracking clock which a write element can use to write data to the magnetic medium with a uniform spacing regardless of magnetic medium speed.

Abstract: A servo information reproducing method reproduces servo information from a recording medium by a head, where servo regions recorded with the servo information and data regions recorded with data coexist on the recording medium. The servo information reproducing method includes a setting step for setting a sense current which is supplied to the head when reproducing the servo information from the servo region to a value larger than that of a sense current which is supplied to the head when reproducing the data from the data region.

Abstract: A disk drive unit and an error recovery method for the disk drive unit which can reduce processing time for ERP in resetting, thereby shortening response time to the reset is described. A normal error recovery procedure is executed if there is no reset request when a write error occurs, but if there is a reset request pending, a data record in which a write error occurs is registered as a defective position (e.g. sector) and an alternate (spare) position is assigned to accelerate the time when the drive can respond to the reset instruction. Data records with alternate positions assigned as a part of the reset activity are specially marked so that alternate position assignment can be undone as soon as is appropriate, for example, when the record is next read or written.

Abstract: A method for eliminating wiggle noise in a disk drive storage device including a magnetic thin film head and a disk provided with an alternate servo sector and a data sector is characterized by the step of writing deliberately arbitrary data in a data sector following a servo sector where there has occurred an error caused by the wiggle noise during retrieving the servo information, thereby eliminating the wiggle noise.

Abstract: The system for gap positioning optimization in a tape drive takes advantage of the presence of a pair of read heads, located one on either side of the write head, to precisely determine the boundary between the inter-block gap and the data blocks adjoining the inter-block gap. In particular, the servo mechanisms in the tape drive note the location of the boundary between the present data block and the inter-block gap formed a the end of the present data block. When the tape is repositioned between data read/write operations, this servo information is used to identify this boundary to initiate the subsequently received data read/write operation. A predetermined amount of inter-block gap is provided at the end of the data block to ensure that subsequently received data is not written on top of the present data block or the overwriting of the next data record begins at the beginning of the data block.

Abstract: The present invention relates to a servo control apparatus of a disk recording system and particularly to a servo control apparatus and method which are capable of controlling position of a head for recording digital data on a disk as recording media and reading the digital data.

Abstract: An apparatus and method are disclosed for determining a maximum magnitude of bias current that can be safely applied to a head of a disc drive. The disc drive comprises a head disposed adjacent a rotatable disc having a recording surface on which data are magnetically stored, a preamplifier circuit which selectively applies bias currents to the head, and a head bias current selection circuit, operably coupled to the preamplifier circuit, which first determines the maximum magnitude of bias current that can be applied to the head in relation to a maximum power dissipation rating of the head and voltage measured across the head when at least one initial bias current of selected magnitude is applied to the head. Thereafter, a range of bias currents having different magnitudes less than or equal to the maximum magnitude are selected and evaluated to select an optimum magnitude for subsequent use by the drive.

Abstract: A system and method is provided to improve the jitter performance of high frequency synthesizers used in read/write channel circuits. The frequency synthesizer is implemented with multiple phase locked loops arranged in a cascaded fashion to increase the update rates at which the cascaded loops operate at for a given frequency resolution of the synthesizer. The cascaded or staged phase locked loops may be utilized for generating read, write, and servo clocks for a read/write channel circuit. The cascaded phase locked loops may also be arranged such that one or more stages are shared to generate the read, write or servo clocks.

Abstract: A magnetic storage apparatus exploits the inherent characteristics of a magnetoresistive element to improve the performance of a magnetic head employing the element. Variations in element height or element thickness of the magnetoresistive element are considered in the selection of a sense current appropriate to the element size, by measuring the voltage between the terminals of the magnetoresistive head and controlling the sense current so that the output reference voltage approaches a predetermined value. In another embodiment, the sense current is controlled so that the voltage amplitude or a reference amplitude are set to a predetermined value. In both embodiments, a conversion table is preferably used to relate voltage amplitudes with sense currents, whereby an appropriate sense current is selected based upon the voltage amplitude.

Abstract: A magnetoresistive sensor and preamplifier system for sensing magnetization patterns in a magnetic disk based digital data storage and retrieval memory with a grounded magnetoresistive sensor The signals from the magnetoresistive sensor are coupled by a coupling capacitor to a grounded differential amplifier. The structure of the coupling capacitor in a monolithic integrated circuit determines the passband for the system in passing the magnetoresistive sensor signals.

Abstract: A method for creating a duplicate copy of a tape in which a first tape having a first data set name and a second tape having a second data set name are allocated. Data is written to the first and second tapes so that block for block, the data is located at the same position on each of the tapes. After data is written to one of the tapes, a check is made to verify that the data was written correctly. If an error is detected in writing the second tape, an error flag is set that indicates a copy of the first tape needs to be made. At various stages of the process, checks are made to determine if error flag is on. If the error flag is detected, writing the second tape is suspended.