Abstract: A combined bulk thermal-assister and bulk eraser. The bulk thermal-assister is configured to produce a temperature in a magnetic-recording disk in a hard-disk drive when the hard-disk drive is disposed in the bulk eraser. The temperature is about equal to a second temperature greater than a first temperature of the magnetic-recording disk. The bulk eraser is configured to erase recorded information from the magnetic-recording disk at the second temperature.

Abstract: A signal processing circuit performs processing for an analog signal output from a head. The signal processing circuit includes: a conversion section that generates a digital signal based on the analog signal; a first filter that equalizes the output of the conversion section; a demodulation section that demodulates data from the output of the first filter; a modulation section that modulates a waveform based on the data demodulated by the demodulation section; a second filter that equalizes the output of the modulation section; and an adaptation section that adapts the response of the second filter such that the output of the second filter becomes equal to the output of the conversion section.

Abstract: A sample and hold circuit is disclosed that provides longer hold times. The sample and hold circuit can be used in a disc drive to provide improved read-to-write and write-to-read mode transitions. The sample and hold circuit has an input and an output, and includes at least one capacitive element for retaining a charge. The capacitive element is connected to a node between the input and the output. The sample and hold circuit includes at least one input switch to selectively connect the capacitive element to the input and at least one output switch to selectively connect the capacitive element to the output. In addition, an amplifier is connected to the node and has an offset voltage. In this manner, a voltage drop across at least one of the input and output switches is limited to the offset voltage.

Abstract: The present disclosure relates to a magnetic recording head having a slider media bearing interface surface with surface modifications configured to reduce friction and/or stiction friction properties between the head slider media bearing interface surface and a recording medium. The present disclosure also relates to a tape drive system, a method of formatting a recording medium using such a magnetic recording head, and the resulting formatted media.

Abstract: Disclosed is a method, for erasing data from a magnetic tape storage medium (92) housed in a cartridge (86) containing a memory in which are stored the last written track position (yy) of the last written, most recent information and the last track position (xx) of past information written in the past and remaining unerased, comprising: the step of reading out of the memory (91) the last written track position of the most recent information and the last track position of the past information; the step (S124) of determining whether the data should be erased up to the last written track position of the most recent information or up to the last track position of the past information; and the step (S126, S128) of erasing the data up to the determined position, thereby shortening the data erase time of the magnetic tape while completely solving a security problem by making provisions to completely erase the data of the most recently written information or the data of the past information written in the past and re

Abstract: Provided is a smear-removing method that can remove smear of a manufactured thin-film magnetic head. The method is performed to a thin-film magnetic head including an MR effect element for reading data having two electrode layers sandwiching an MR effect multilayer as a magneto-sensitive portion therebetween. The method comprises the step of applying a stress voltage less than a breaking voltage of the MR effect element between the two electrode layers to burn off smear. In the method, it is preferable that the stress voltage is applied while an electric resistance or an output voltage of the MR effect element is measured, and the stress voltage is increased until the value of the electric resistance or the output voltage reaches an upper limit specified value specified from a value of an electric resistance or an output voltage in a normal case where smear is not present.

Abstract: A disk drive is disclosed comprising a disk including a plurality of servo sectors, a head actuated over the disk, the head for generating a read signal, and a gain control circuit for adjusting a gain of the read signal in response to a gain setting. A bias setting is initialized for the head, and the gain setting for the read signal is initialized. The read signal is processed to detect at least one of the servo sectors, and when at least one of the servo sectors is not detected, the gain setting is adjusted. The read signal is processed with the adjusted gain setting to detect at least one of the servo sectors, and when at least one of the servo sectors is not detected with the adjusted gain setting, the bias setting is adjusted in response to the adjusted gain setting.

Abstract: Circuits, systems, and methods for generating and calibrating bias for a magneto-resistive (MR) sensor. The circuit relates to a preamplifier circuit in a magnetic storage system, including an amplifier having an input coupled to a first MR sensor node, a first feedback path comprising a feedback resistor, the path configured to receive an amplifier output from the amplifier and to provide a feedback output to the first MR sensor node, a charging circuit configured to generate a current, apply the current to the first MR sensor node, and sample a voltage between the first MR sensor node and a second MR sensor node to produce a sampled voltage, the charging circuit operating when the feedback path is activated, and a bias circuit configured to apply a bias voltage across the first and second MR sensor nodes and to adjust the bias voltage to match the sampled voltage, the bias circuit operating when the feedback path is deactivated.

Abstract: A current mirror circuit providing a fast turn on time. A node within the circuit is held at a first voltage when the current mirror is off to permit the node voltage to quickly reach a necessary value when the current mirror circuit is turned on.

Abstract: An apparatus, system, and method are disclosed for dynamically controlling a recording head substrate bias voltage. The apparatus includes a midpoint module and a substrate module. The midpoint module calculates a midpoint voltage of a plurality of data read elements and servo read elements contained in the head. The substrate module calculates a substrate bias voltage. The apparatus, system, and method dynamically control the substrate bias voltage post-assembly, minimizing certain head degradations and extending the life of associated head readers.

Abstract: A method for erasing a disk of a hard disk drive. The method includes moving the hard disk drive adjacent to an erasure head that emanates a magnetic field. The magnetic field and moving hard disk drive cause a disk of the hard disk drive to spin under a Lorentz force created by the magnetic field and moving disk. The magnetic field is applied by the erasure head for a duration that causes erasure of the entire disk. The spindle motor is not activated during the entire process. Not activating the spindle motor eliminates any Faraday coupling from the erasure head into the motor.

Abstract: A method of manufacturing of a hard-disk drive using a bulk eraser for erasing recorded information on a magnetic-recording disk. The method includes providing a bulk eraser that produces magnetic-flux density in a gap sufficient to erase recorded information from a magnetic-recording disk, a hard-disk drive, a disk-stack having at least one magnetic-recording disk, and a drive motor for rotating the magnetic-recording disk. The method also includes configuring a plurality of magnets and a structure of the bulk eraser such that magnetic-flux density is oriented parallel to and in a radial direction of the magnetic-recording disk; and rotating the magnetic-recording disk. The method further includes inserting the hard-disk drive into the gap of the bulk eraser; and erasing recorded information from the magnetic-recording disk located in the gap; and removing the hard-disk drive from the gap.

Abstract: A bulk eraser for erasing recorded information on a magnetic-recording disk. The bulk eraser includes at least three magnets and a structure magnetically coupled with the at least three magnets to produce magnetic-flux density in a gap. The gap has a first portion, a second portion and a third portion, such that a first magnet and a second magnet are disposed with opposing end poles across the first portion. The at least three magnets and the structure are configured to produce a magnetic-flux density in the second portion sufficient to erase recorded information from a portion of at least one magnetic-recording disk in a disk-stack when a hard-disk drive is inserted into the second portion. In addition, the at least three magnets and the structure are configured to direct the magnetic-flux density in a substantially radial direction of the portion of the magnetic-recording disk in the second portion.

Abstract: Embodiments of the present invention allow for media erasure. Various embodiments allow for controlling an actuator based on feedback signal measurements and disk phase to seek a head across a surface of a disk systematically for an erasure operation. Also, in various embodiments, a substantially repeatable seek motion of a head across a stroke may be determined, and launch points at which the head is launched over a disk in the seek motion for erasing at least a portion of the disk are determined based on disk phase.

Abstract: A recording system employing a magneto-resistive (MR) element senses a resistance value of the MR element and generates one or more MR resistance (MRR) signal values based on the sensed MR element resistance value. The MRR signal values might be, for example, current or voltage values proportional or inversely proportional to the MR element resistance value. The MRR signal values might be employed to control one or more of: i) a unity gain bandwidth of a bias loop for the MR element, ii) an MR read head preamplifier low corner frequency, and iii) a slew rate across the MR element.

Abstract: A magnetic data storage system according to one embodiment includes a head having a reader, the reader further comprising a shield, a sensor, and leads coupled to the sensor; a charge clamp circuit electrically coupling the shield to the leads; and a bias circuit for passing a bias current through the sensor via the leads; wherein the bias circuit maintains a potential of the shields at about a ground potential.

Abstract: A disk drive controller including a preamplifier and a controller is disclosed, in which communications between the controller and the preamplifier are carried out over at least some shared terminals and conductors. A first pair of differential lines is provided to communicate data, sensed at read/write heads of the disk drive, from the preamplifier to the controller, and a second pair of differential lines communicates data to be written to the disk drive from the controller to the preamplifier. Control signals are communicated over a serial interface between the controller and preamplifier, over the first pair of differential lines, so that serial communication can be carried out simultaneously with the writing of data from the controller to the preamplifier. Alternatively, the control signals are communicated over the second pair of differential lines, simultaneously with the reading of data from the preamplifier to the controller.

Abstract: A hard disk drive includes a chassis which supports a “sealed” housing containing a data storage magnetic disk, and read/write heads and actuator. The housing also contains an erasure device which generates a magnetic or other field or emanation for erasing the disk, so that the erasing field or emanation need not penetrate the sealed housing to effectuate erasure. A backup power supply provides power to the erasing device so that erasure can occur even in the absence of external power. A bus- or network-actuated arrangement couples power to the erasure device so that many hard drives may be simultaneously erased.

Abstract: An apparatus and method for controlling the common mode voltage across a data storage device write head. The write current is supplied by a first plurality of parallel current sources each independently activated to limit the common mode voltage generated across the write head. A plurality of parallel resistive elements responsive to current supplied by a second plurality of parallel current sources bias an output transistor that further controls the write current. Each of the plurality of parallel resistive elements and each of the second plurality of parallel current sources is also independently activated to limiting the common mode voltage generated across the write head.

Abstract: A permanent magnet degausser includes at least one magnetic field generator comprising magnetic elements arranged near a media conveyance path and a conveyor for transporting magnetic media through a magnetic media conveyance path. A passive belt or protector plate may be provided to assist the passage of the magnetic media through the applied magnetic field. The conveyor may be a continuous motion conveyor belt including cleats for holding the magnetic media or a reciprocal media conveyor including magnetic storage media bin. The magnetic field generator may include permanent magnets of varying intrinsic coercivities and/or remanences.

Abstract: Embodiments of the present invention provide a mixed-mode amplifier for amplifying signals in data storage devices such as disk drives. In one embodiments, a circuit for amplifying data signals comprises a magnetoresistive sensor having a bias voltage applied thereto; a signal amplifier which amplifies a signal detected by the magnetoresistive sensor having the bias voltage applied thereto; a feedback control block which is coupled to an output of the signal amplifier and outputs a feedback current used to vary a loop gain of the circuit; a bias setting circuit which outputs a bias setting current; and a transimpedance amplifier which receives the bias setting current from the bias setting block and the feedback current from the feedback control block and generates the bias voltage applied to the magnetoresistive sensor.

Abstract: According to one embodiment, a disk drive is provided which has a head amplifier having a function of, at a data recording time, outputting AC pattern data to a write head prior to the recording of the write data to allow it to be recorded on a write splice section on a disk medium. The write head records an AC signal pattern of a high frequency on the write splice section on the disk medium according to an output timing of a write gate and then write data is recorded with a preamble as a header.

Abstract: Provided is an apparatus for adjusting static attitude of a thin film magnetic head attached to a flexure of a head arm assembly. The apparatus has an adjusting unit for bending the flexure, a laser emitter unit for irradiating a laser beam to a bent area of the flexure a measuring unit for measuring a static attitude angle of the thin film magnetic head, and a computer system including a CPU and a memory unit in which adjustment conditions corresponding to static attitude angles of the thin film magnetic head are previously ranked and memorized. The CPU is configured to retrieve from the memory unit a particular adjustment condition corresponding to a measured angle supplied from the measuring unit and supply the retrieved adjustment condition to the adjusting unit, enabling the adjusting unit to bend the flexure based on the retrieved adjustment condition supplied from the computer system.

Abstract: When a disk sector is written to, a bit for the sector is set indicating that the sector will require secure data disposal (SDD) to be run on it. To save time during end of life disposal, SDD is executed only on sectors whose bits indicate that they have been written to. SDD can be executed on each dirty sector in one operation at end of life or incrementally during use as disk activity permits.

Abstract: A circuit for measuring resistance of a magnetoresistive head. First and second current biasing circuits are respectively coupled to opposite sides of the head. The first biasing circuit includes a first resistance, and the second biasing circuit includes a second resistance. First and second current mirrors are respectively coupled to the first and second biasing circuits. A current leg is coupled to the current mirrors. The current mirrors drive current in the resistances so that a first voltage across the first resistance is substantially equal and opposite to a second voltage across the second resistance. The biasing circuits bias current through the head such that a voltage on the first side of the head is close to the first voltage and a voltage on the second side of the head is close to the second voltage, so that the common mode voltage of the head will be close to zero.

Abstract: A method for protecting a magnetic head according to one embodiment includes reducing a relative humidity in a vicinity of a magnetic head by passing an elevated bias current through a sensor of the head during at least some time periods when the sensor is not in use for reading data, the elevated bias current being chosen to be sufficient to heat the sensor to a level which will reduce the local relative humidity to below a threshold level for reducing or eliminating corrosion of the sensor. Additional methods are also presented.

Abstract: Embodiments of the invention relate to erasing data recorded on a magnetic disk with increased certainty by using an external magnetic field. One embodiment is directed to a method for erasing data recorded on a magnetic disk, which is housed in a magnetic disk drive, by using an external erasure magnetic field generated by an external erasure magnetic field generator. The method comprises the steps of: moving a first magnetic disk drive within an external erasure magnetic field in a moving state appropriate for the type of the first magnetic disk drive, and erasing data recorded on a magnetic disk in the first magnetic disk drive; and moving a second magnetic disk drive, which differs in type from the first magnetic disk drive, within an external erasure magnetic field in a moving state that differs from the moving state of the first magnetic disk drive, and erasing data recorded on a magnetic disk in the second magnetic disk drive.

Abstract: An output of a magnetic head changes depending on the environmental temperature of a magnetic disk. In particular, under cold temperature conditions, an output of the head largely decreases mainly due to an increase in coercivity of a magnetic recording medium, which degrades an error rate. In one embodiment of the invention, sense-current optimization processing of a magnetic disk drive comprises the steps of: measuring the environmental temperature; and after a sense-current value which is set from the viewpoint of the reliability of the magnetic head is defined as an upper limit, finding out a sense current Is that can achieve the best error rate (BER) at the temperature. While changing a value of the sense current Is inside the magnetic disk drive, an error rate is measured. Then, a sense current Is_opt at which the best error rate properties are achieved is selected as a new set value.

Abstract: An apparatus and method for determining a resistance of a magneto-resistive head. A current drawn by the head, in response to a fixed bias voltage across the head, is converted to a zero temperature coefficient current such that when supplied to a resistor connected to an input terminal of a comparator the effects of variations in the resistance value are avoided. An output signal of the comparator indicates the resistance of the magneto-resistive head.

Abstract: A storage device includes a storage unit, a timer unit and a bias current applying unit. The storage unit stores, in advance, a value of a waiting time until application of a bias current to the driving unit to eliminate an external force applied to an actuator after completion of positioning, and a value of a bias current to be applied to the driving unit after the elapse of the waiting time, in association with a track position. The timer unit reads the waiting time from the storage unit and counts an elapse of the waiting time. The bias current applying unit reads the bias current value from the storage unit and applies the bias current to the driving unit after the elapse of the waiting time.

Abstract: A receiver has a first input port and a second input port both coupled to a differential amplifier through first and second input capacitors. A bias circuit coupled to the core side of the first input capacitor and to the core side of the second input capacitor is configured to provide a selected voltage to at least one of the first input and the second input of the differential amplifier. In one embodiment, a common mode bias circuit provides a common mode voltage to both inputs of a differential amplifier. In a particular embodiment, a run length detector monitors the output of the differential amplifier and provides a run length feedback signal or an average bit density feedback signal to the set the selected voltage between periods of data reception.

Abstract: A magnetic data eraser includes a power supply circuit, a receptacle for accommodating a magnetic recording medium or a device incorporating a magnetic recording medium, primary and secondary coils wound around an outer periphery of the receptacle. The primary coil is connected to the power supply circuit. The secondary coil is short-circuited. Excitation of the primary coil through energization by the power supply circuit generates an induced current in the secondary coil, thereby making an interaction between the primary and secondary coils. The interaction generates an alternating magnetic field, whereby the magnetic recording medium is degaussed, so as to erase magnetic data recorded in the medium.

Abstract: A multistage decoder circuit has an error reduction stage that includes an adaptation circuit. The adaptation circuit provides adaptable error reduction as a function of bit error rate. The multistage decoder circuit has an energization control circuit that couples to the adaptation circuit. The energization control circuit controls an energization of the adaptation circuit as a function of actual or expected channel quality.

Abstract: Provided is a method of compensating for a bias for efficient servo control of a hard disk drive, and optimally compensating for bias force based on the elapsed usage time of a hard disk drive, and a bias force profile generation method, recording media, and a hard disk drive appropriate to the bias compensation method. The bias compensation method for compensating for a bias force applied to a magnetic head of a hard disk drive includes: measuring the bias force at the current position of a head; selecting a bias force profile having a bias force similar to the bias force measured at the current position of the head, from among a plurality of bias force profiles that are obtained by measuring bias forces of a disc from based on the elapsed usage time of the hard disk drive; and compensating for the bias force according to the selected bias force profile.

Abstract: WORM safeguards are provided in a magnetic disk drive in which the disks are pre-magnetized or pre-recorded such that all magnetic domains on each recording surface are completely aligned pointing in the same direction. A special write head which can magnetically write only in the direction opposite to the pre-magnetization orientation is also provided.

Abstract: A magnetic disk apparatus including: a disk holding data as magnetic information on a magnetic recording film; a head to perform writing and reading of the magnetic information; a rotary actuator to move the head in a radial direction of the disk; plural heat elements in the head to locally heat the disk; a write element in the head to apply a magnetic field to the disk; and means for selecting at least one heat element from the plural heat elements, wherein the means for selecting the heat element selects at least one heat element from the plural heat elements so as to bring a center line of an area heated by the heat element and a center line of the position of the magnetic field generated by the write element into approximate correspondence, in correspondence with a relative angle between the head and a direction of movement of the disk.

Abstract: Embodiments in accordance with the present invention erase a desired area on a recording surface of disk or disk drive apparatus. According to an embodiment, a hard disk drive (HDD) performs erase on a recording surface by moving a head element unit at one-half a servo track pitch with reference to a servo address. Before actual erase is started on the recording surface, the HDD generates a management table configured based on servo addresses from a management table configured based on data tracks. At an erase process, the HDD sets parameters in accordance with the zone and skips a management area with reference to this management table based on the servo addresses.

Abstract: A magnetic storage system includes a disk, a head, an actuator, a read channel, and a main controller. The main controller causes the head to read a data block of a selected track of the disk at each of a plurality of fixed offsets from a center of the selected track. The main controller samples a gain in the read channel a plurality of times while the head is reading the data block at each of the plurality of fixed offsets to obtain a plurality of gain samples for each of the plurality of fixed offsets. If the data block was written off-track with a non-constant offset, the main controller determines an approximate starting position and an approximate rate of change of an off-track deviation of the data block based on the plurality of gain samples for the plurality of fixed offsets.

Abstract: A technique for de-gaussing the pole tips and yoke of a write transducer in a perpendicular magnetic recording system is provided. An oscillator in the read channel is configured to produce an adjustable signal pattern output to the preamplifier when a write operation ends for a given time and at a predetermined frequency, such that as the preamplifier write current decays, it decays with transitions (polarity reversals). This results in a decaying AC field being applied to the write transducer at the end of a media write operation, effectively de-gaussing it and reducing the effects of remanent magnetization remaining in the poles and yoke of the magnetic recording head after a write current is turned off. This defeats a potential pole tip lockup or yoke lockup circumstance in the magnetic recording media which can result in an inability to write further data or a possible erasure of valid data on the hard disk with which the write head is associated.

Abstract: A storage device includes a storage unit, a timer unit and a bias current applying unit. The storage unit stores, in advance, a value of a waiting time until application of a bias current to the driving unit to eliminate an external force applied to an actuator after completion of positioning, and a value of a bias current to be applied to the driving unit after the elapse of the waiting time, in association with a track position. The timer unit reads the waiting time from the storage unit and counting an elapse of the waiting time. The bias current applying unit reads the bias current value from the storage unit and applying the bias current to the driving unit after the elapse of the waiting time.

Abstract: A method for controlling a burnish cycle to minimize cycle time is disclosed. MR sensor resistance measurements are used to monitor interference with the recording surface and when clearance is not detected, steps are taken to fine tune the interference signal.

Abstract: In a hard disk drive (HDD), biases are measured across all zones of a disk, and nonlinear bias components are extracted. Upon a change in operational condition of the HDD, biases are measured at two reference positions on the disk so as to estimate a corresponding change in a linear bias component across all zones of the disk. The bias at a given position of the disk is then calculated based on the estimated linear bias component and the extracted nonlinear bias component.

Abstract: A magnetic data system according to one embodiment includes at least one reader formed above a substrate, the at least one reader further comprising a shield and a magnetoresistive (MR) sensor. A first circuit sets a voltage (Vsub) of the substrate to about a voltage (Vshield) of the shield of the at least one reader.

Abstract: A magnetic data system according to one embodiment includes a head having a plurality of readers formed above a common substrate, each reader further comprising a shield and a sensor, a bias circuit associated with each reader for passing a bias current through the sensor thereof, wherein the bias circuits are floating. A charge clamp electrically couples each shield to the associated bias circuit. A shield biasing circuit is operatively coupled to each shield for setting a potential of the shield independently of the bias current.

Abstract: A magnetic sensor includes a magnetoresistance element having a peak of a thermal fluctuation strength of magnetization under a magnetic field having a certain frequency, a frequency filter connected to the magnetoresistance element and having its transmittance decreased or increased in substantially the frequency of the magnetic field to output a signal corresponding substantially to the peak of the thermal fluctuation strength of magnetization, and a detector connected to the frequency filter to detect the magnetic field based on the signal of the frequency filter.

Abstract: Embodiments of the invention improve efficiency in alternating-current demagnetization of a magnetic recording medium. In specific embodiments, magnet fields in a direction slanting to an easy direction of magnetization of recording layer magnetization of a medium in rotation are applied.

Abstract: In a data-recording mode, a driver circuit supplies a recording head with a recording current corresponding to write data. In a degaussing mode, the driver circuit supplies the recording head with a degaussing current for eliminating the residual magnetism of the head as the recording current. The degaussing current has a rising period and falling period set longer than those of the recording current supplied in the data-recording mode.

Abstract: Embodiments of the invention provide a method for recording bursts on a disk and a related apparatus. In accordance with an embodiment of the invention, a method for recording bursts on a burst field of a servo sector of a disk comprises generating a first write current corresponding to burst data provided by a write channel circuit, and generating a second write current having a higher frequency than the first write current using a high frequency AC current generator, wherein the high frequency AC current generator is independent from the write channel circuit. The method further comprises selectively applying the first write current to a write head in response to a signal and selectively applying the second write current to the write head in response to the signal.

Abstract: Described herein are media drives for writing information to a media (e.g., a tape media), systems for storing information on a storage medium, and methods of writing information to a media. The devices, systems and methods described herein are error tolerant in that they may permit only a limited number (or arrangement) of bad blocks in an envelope to be written before they erase at least a portion of the envelope that has already been written, and move to a different region of the storage media and re-write the envelope.

Abstract: The present invention provides a magnetic writer. The magnetic writer comprises a write circuit, a write pole, a first write coil for inducing a first magnetic field in the write pole by a first current provided by the write circuit, and a second write coil for inducing a second magnetic field in the write pole by a second current provided by the write circuit. The write circuit provides a first current through the first coil and a second current through the second coil. The write circuit controls the direction of the first current and the second current so that, during writing, the first magnetic field and the second magnetic field have components perpendicular to the air bearing surface that are in the same direction. When not writing, the first magnetic field and second magnetic field have components perpendicular to the air bearing surface in opposite directions.