Abstract: A method for detecting the degree of wear of a magneto-resistance (MR) effect type magnetic head element for reading a magnetic signal by use of a simple structure is disclosed. The degree of wear of an MR head for reading a magnetic signal from a magnetic tape is detected based on a value of resistance of an MR element by a head wear detecting circuit. A signal indicative of the degree of wear of the MR head is supplied to an alarm generating circuit for example, to generate an alarm informing of the life of the MR head.

Abstract: A reproduction signal 10 is processed in an AD converter 4 and an equalizer 16 to be a decoder input signal 12. The decoder input signal 12 is used to calculate a phase error signal 25 and a quality judgement signal 26. A phase-frequency error detection circuit 22 retains a sign of the phase error signal 25 obtained when the quality judgement signal 26 is changed in quality from “good” to “bad”. The phase-frequency error detection circuit 22 then outputs, as a phase-frequency error signal 27, the phase error signal 25 when the signal quality is “good”, and a given value corresponding to the retained sign when the signal quality is “bad”. A voltage controlled oscillator 9 generates a recovered clock signal 11 whose frequency is based on the oscillation control signal 15 generated by the phase-frequency error signal 27.

Abstract: Provision of a highly reliable magnetic recording medium with able to record further high density recording, usable advantageously as a magnetic tape for recording computer data, and having a further improved SNR, and a method for reproducing signals magnetically recorded on a magnetic recording medium to reproduce more desirably magnetic recording such as computer data with high density recording or the like. The magnetic recording medium having, on either side of a flexible nonmagnetic support, a nonmagnetic layer containing a nonmagnetic powder and a binder, and a magnetic layer containing a ferromagnetic powder and a binder, having a thickness in the range of from 0.2 to 0.6 &mgr;m in this order, where a laminated head is used for reproduction. The method for reproducing signals magnetically recorded medium having, on either side of a flexible nonmagnetic support, a nonmagnetic layer containing a nonmagnetic powder and a binder, and a magnetic layer, with a thickness ranging from 0.2 to 0.

Abstract: The present invention provides a method for magnetic transfer, the method including the steps of arranging ring shape head electromagnets at least on one of upper and lower surfaces of the slave medium, rotating the slave medium or the ring shape head electromagnet in track direction, performing initial DC magnetization on the slave medium in advance in track direction by applying magnetic field in track direction on the surface of the slave medium, bringing the master carrier for magnetic transfer closely together with the slave medium processed by the initial DC magnetization, and performing magnetic transfer by applying magnetic field for transfer in track direction reverse to the direction of the initial DC magnetization on the surface of the slave medium.

Abstract: A read/write system for reading information from a magnetic storage medium using a magnetoresistive head and for providing an output signal representative of the information read includes a differential pair circuit, an input voltage offset compensation circuit, and an input current offset compensation circuit. The differential pair circuit is ac coupled to first and second input signal nodes and includes first and second transistors, first and second load resistors, and a current generator. The input voltage offset compensation circuit is coupled to the differential pair circuit and includes a switch network and a Gm stage. The input current offset compensation circuit is coupled to the differential pair circuit and includes an integrator circuit and first and second biasing resistors.

Abstract: The invention relates to a technique for shock estimation and write termination control in a disk drive. During a data write operation, a selected track's embedded servo sectors are read to generate position error signal values. A write unsafe limit is provided for terminating a data write operation if at least one position error signal value exceeds the write unsafe limit. A shock event limit is provided, and if a current position error signal value is less than the write unsafe limit value, then a function value is calculated based on the current position error signal value and a previous position error signal value. If the calculated function value exceeds the shock event limit, a data write operation is terminated. Otherwise, the operation is continued.

Abstract: Servo marks on a storage medium such as a magnetic disk can be detected without fail by correcting misalignments or dislocations of servo gates due to an eccentricity of the storage medium, changing of read/write heads, etc. Amounts of displacements of servo marks with respect to corresponding reference positions thereof are recorded on the storage medium in advance, and an amount of displacement of each servo mark detected is read from the storage medium. A counter, which outputs the timing at which each servo gate is formed, is controlled based on the amount of displacement of each servo gate, so that a servo gate is formed at the position which is shifted by the amount of displacement read from the storage medium from a servo gate forming position corresponding to the reference position of the servo mark detected.

Abstract: A disk drive system is disclosed that includes a disk device coupled to control circuitry. The control circuitry encodes data using a modulo code. The control circuitry separates the data into blocks and encodes the data by inserting stuff bits between blocks according to the modulo code. The control circuitry converts the encoded data into a write signal and transfers the write signal to the disk device. The control circuitry also receives a read signal from the disk device and converts the read signal into a data signal. The data signal represents blocks of data separated by stuff bits. The control circuitry detects errors in a block of data by determining the modulo value of the block of data and the following stuff bits.

Abstract: To obtain a large capacity magnetic recording medium capable of recording at a super high density of 3 Gbit or more per one square inch and a magnetic storage apparatus, a magnetic recording medium is prepared by disposing orientation control layers 31, 31′ having at least a B2 (CsCl) structure on a substrate 30, disposing a first underlayer comprising Cr and a second underlayer containing at least one element selected from Cr, Nb, Mo, Ta, W and Ti and having a lattice constant greater than that of the first underlayer and then forming a magnetic layer comprising Co as the main ingredient.

Abstract: A digital temperature monitor (DTM (24) includes a proportional-to-absolute temperature (PTAT) sensor (44) and reference circuit (48) coupled to the inputs of a comparator (42). The DTM (24) monitors the temperature of adjacent and/or proximate integrated circuitry. The method includes the steps of providing a reference signal to the comparator (42), increasing the reference signal voltage, and determining the temperature of an integrated circuit by determining when the reference signal is greater than the PTAT sensor (44) output voltage. The DTM (24) may be implemented as part of a hard-disk drive preamplifier circuit (22).

Abstract: A method and apparatus for determining a lifetime for a medium to fail due to thermal decay of a magnetization pattern is provided. Different stress magnetic fields are applied to a write head for writing to a machine-readable medium resulting in a magnetic field on the medium. A time to failure, corresponding to each of the different stress magnetic fields, is determined, the time to failure being an amount of time for an amplitude of a signal on the medium to degrade beyond a predetermined failure criteria. A time to failure without a stress magnetic field is determined based on the corresponding times to failure determined for each of the different stress currents.

Abstract: A tape reader is designed to read down-level linear track tapes having a multiple number of new tacks in the positions of each older wider track and having tape subject to pack level tape distortions which may result from environmental stresses and inter-use delay time. If tracks are displaced with respect to ideal servo reference positions, then optimal down-level reading may require selecting segments from different new track choices along the length of the tape. Decision choices of tracks and longitudinal break points are based on a; combination of gathered metrics per tape and engineering knowledge of each product. These data are stored first in internal memory. Longer-term memory storage particular to each tape may include cartridge memory either in the form of possible cartridge chip memory or writing to a section of tape in each cartridge. Decisions may be optimized with increasing number of read cycles and supplemented by knowledge in longer-term cartridge memory.

Abstract: A method of writing servo tracks on the disk surfaces of a hard disk drive. The method involves simultaneously writing partial servo tracks, called servo wedges, until a complete first set of servo wedges is written on all the disk surfaces. Then the disks are rotated until the heads of the disk drive are correctly positioned to simultaneously write subsequent servo wedge sets. This process is repeated until enough servo wedge sets are written to complete a first servo track on all the disk surfaces. Then, the heads are pivoted to a new radial position to begin writing a new servo track just as before. Simultaneously writing servo wedges advantageously expedites the often costly servo writing process.

Abstract: A disk drive system is disclosed that includes a disk device coupled to control circuitry. The control circuitry includes a read channel with a detector that detects servo mark sub-patterns and correlates the detected servo mark sub-patterns to detect a servo mark. The detector includes matched filters to detect the sub-patterns.

Abstract: The present invention is directed to a system and method for reading and writing N-way mirrored storage devices. A method of reading data in a data storage system, where the data storage system may include a first data storage device, a second data storage device and a third data storage device, is provided. A first item of data is read from a first data storage device, a second item of data is read from a second data storage device, and a third item of data is read from a third storage device. The first item of data from the first storage device is compared with the second item of data from the second storage device and the third item of data from the third storage device. If the first item of data matches at least one of the second item of data and the third item of data, the first item of data is valid. If the first item of data does not match at least one of the second item of data and the third item of data, the second item of data is valid.

Abstract: A magnetic recording system includes a magnetic recording medium including a magnetic layer, the magnetic layer being composed of magnetic grains, and a magnetic head including a recording unit and a reproducing unit. An orientation of an axis of easy magnetization of the magnetic grains is three-dimensionally distributed. An average angle between a direction of an axis of easy magnetization of each of the magnetic grains and a surface of the magnetic recording medium is within a range of 20° to 30°. A squareness ratio Mr/Ms of a remanent magnetization Mr of the magnetic recording medium to a saturation magnetization Ms of the magnetic recording medium is equal to 0.5 or more and is equal to 0.6 or less. A recording density of information which is recorded onto the magnetic recording medium is equal to 360 kfci or more.

Abstract: A system for recording the history associated with writing data onto rewriteable media includes an access head for writing data onto the media and reading data from the media. A drive motor moves the media past the access head. A write formatter formats data into a device block to be written onto the media. A read formatter detects errors in data read from the media. A control unit determines an error recovery procedure based on an error detected in reading the media and enables the write formatter to insert an indication of the error recovery procedure into the device block. The error recovery procedure is then attempted. The process is repeated until either a successful write occurs or the media is determined to be bad.

Abstract: The present invention provides a method for magnetic transfer, said method comprising the steps of arranging permanent magnets each having magnetic field symmetrical to the axis of the magnetic pole at least on one of upper or lower surfaces of the slave medium with the axis of the magnetic pole disposed in parallel to the surface of the slave medium, rotating the slave medium or the permanent magnet in track direction, performing initial DC magnetization on the slave medium in advance in track direction, bringing the master carrier for magnetic transfer closely together with the slave medium processed by said initial DC magnetization, and performing magnetic transfer by applying magnetic field for transfer in track direction reverse to the direction of the initial DC magnetization on the surface of the slave medium.

Abstract: A method and system for adaptively limiting an off-track recovery displacement of a recording head during an off-track data recovery operation. A head disk assembly (HDA) includes an actuator that positions the recording head in accordance with an actuator control signal. First, an off-track recover displacement threshold is determined utilizing an off-track data field which overlays an on-track data field. The recording head is displaced with respect to the track center until the on-track data field is read. The relative displacement required to retrieve the on-track data is utilized as the threshold. In response to a failed read attempt, a data recovery procedure commences whereby the recording head is incrementally displaced from the track center while attempting to recover the data. During the DRP, the predetermined off-track recovery threshold is utilized to limit the head displacement such that the input/output (I/O) data integrity of the off-track recovery is ensured.

Abstract: Systems and methods for accumulating data relating to the performance of one or more components of a read channel are described. In one aspect, a programmable channel quality monitor is operable to accumulate performance data corresponding to a recorded test data sequence spanning two or more data sectors of the magnetic medium. The channel quality monitor preferably is incorporated in a disk drive system. A method of accumulating performance data from a read channel also is described. In accordance with this inventive method, an original test data pattern is written to multiple data sectors of the magnetic medium. The original test pattern is read from the multiple data sectors of the magnetic medium to produce a readback test pattern. In this method, performance data relating to a comparison of the original test pattern and the readback test pattern is accumulated.