Abstract: A circuit controls the gain of an amplifier that amplifies an information signal. The circuit includes a buffer that stores two samples of the amplified information signal, and includes a gain-determination circuit coupled to the buffer. The gain-determination circuit generates a gain adjustment that is based on the two samples and that causes the amplifier to shift the amplitude of the amplified information signal to or toward a predetermined amplitude. Such a circuit can provide an initial, coarse gain adjustment to a read-signal amplifier in a disk-drive read channel. Compared to prior read channels, this initial adjustment promotes faster settling of the amplifier gain at the beginning of a data sector. This faster settling allows the data sector to have a shorter preamble, and thus allows the disk to have a higher data-storage density.

Abstract: A circuit and method are presented for detecting a fault in a magneto-resistive head (18). The circuit includes a bias circuit (50) to produce a bias voltage across the head (18) and a pair of resistors (68,70) in series with the head (18) connected to the bias circuit (50) to carry a current (IVMR) from the bias circuit (50) in common with the head. A circuit (102,102′) is provided to determine a ratio of a voltage across the head (18) with respect to a voltage across the head (18) and the pair of resistors (68,70), and a circuit (104,106,104′,106′) is provided for indicating a fault if the ratio falls outside a predetermined range.

Abstract: An amplifying circuit and method are disclosed for amplifying electrical signals, such as electrical signals generated by the read head of a disk drive. The circuit includes a pair of cross-coupled differential amplifier circuits. Each differential amplifier circuit is asymmetric, including two input transistors of different transistor types. For instance, a first of the two input transistors of each differential amplifier circuit may be a bipolar transistor and a second of the two input transistors may be a field effect transistor. By utilizing asymmetric differential amplifier circuits, a relatively wider operating frequency range is obtained.

Abstract: A head apparatus which is tough against disturbing noise and superior in the S/N ratio and which can cope with an increase of the capacity of a recording medium is disclosed. A first playback amplifier for amplifying the playback signal of a MR head and a register circuit for setting the bias current to the MR head are formed as a COS IC. The COS IC is mounted on a suspension together with the MR head. A feeble playback signal outputted from the MR head is amplified by the first playback amplifier once and then transmitted to a mother IC over a pair of signal lines. The amplified playback signal is tough against disturbing noise during transmission.

Abstract: An apparatus marks files within a content archive. The content archive contains a database that has a plurality of content files. The content archive also contains a plurality of entries or records. Each of the entries corresponds to a distinct one of the plurality of content files. Each of the entries also includes a played field that is automatically set when the corresponding content file has been played. The content archive also includes a writing module that is configured to record a new content file to the content archive and, if insufficient space is available, to overwrite a content file for which the played fields are set. According to one aspect, the plurality of entries also includes an entry corresponding to an overwritten content file previously contained within the database that is no longer contained within the database. The database may contain references to content no longer in the database.

Abstract: A magnetic disk device having a head integrated circuit mounted on a magnetic head supporting mechanism. In order to secure the reliability by controlling the integrated circuit temperature below a predetermined level, the difference in the integrated circuit cooling ability which varies with the radial position on the disk is quantified, so that power (signal) sufficient to maintain a constant temperature according to the integrated circuit temperature is supplied to the integrated circuit. Since the cooling ability at a given radial position of the integrated circuit is not exceeded by the power consumption, the integrated circuit temperature can be maintained below a predetermined level.

Abstract: A method of controlling bias supply sources for magneto-resistive transducer (MR) heads to provide essentially the same predetermined lifetime for the MR heads, by determining dependence of head lifetime on bias supply level and on head stripe temperature, and setting a bias supply level for each head based on said dependence of lifetime on bias supply level and on head temperature, to provide essentially the same predetermined lifetime for the heads.

Abstract: A method of controlling magnetic recording in a magnetic recording medium and a control device for the same provides a symmetrical transferred signal waveform of equal magnitude with good reproducibility and performs magnetic transfer with high reliability. In performing initial magnetization prior to performing transfer magnetization, an AC magnetic field, the polarity of which changes in the perpendicular direction Y (or both in the perpendicular direction Y and parallel direction X), is applied to the recording surface of the magnetic recording layer of a magnetic recording medium, and the intensity of the AC magnetic field is gradually decreased with time, to demagnetize the entire magnetic recording layer.

Abstract: The maximum external magnetic field of a magnetic recording medium longitudinal component which is applied to a magnetic recording medium is smaller than an absolute value Hn of a magnetic field at the intersection of a straight line connecting two points of an M-H curve in the longitudinal direction of a soft magnetic backing layer and a tangent of the M-H curve. One of the two points is a point (Hs, Ms) at which magnetization saturates in the first quadrant. The other of the two points is a positive intersection (0, Mr) of the M-H curve and the ordinate. The tangent is at a negative intersection (−Hc, 0) of the M-H curve and the abscissa.

Abstract: A method for forming a magnetic pattern by applying a first external magnetic field to a magnetic recording medium having a magnetic layer to magnetize uniformly the magnetic layer in a predetermined direction and heating locally the magnetic layer while a second external magnetic field is applied thereto, whereby the heated portion is magnetized in the direction opposite to the predetermined direction, wherein the second external magnetic field has a pulse-like magnetic field component. The method can form a fine magnetic pattern efficiently in a medium for high density recording, and a magnetic recording medium and a magnetic recording device capable of recording with high density can be provided economically in a short time.

Abstract: A technique and associated circuitry are provided for measuring a buffered write head voltage, and measurement of thin-film write head DC head voltage in a disk-drive, along with a procedure for calibrating/optimizing the write current amplitude based on the measurement of the buffered write head voltage. A write driver includes a terminating resistor, coupled to the write element of a transducer head in a disk drive, wherein controlling the write current of the write driver includes the steps of measuring the resistance RW of the terminating resistor; measuring the resistance RC of the write element; and generating the write current amplitude based on the resistances RC and RW.

Abstract: A common mode transient reduction circuit for use with an operational transconductance amplifier having a main amplifier and a common mode feedback amplifier coupled to a common bias voltage is disclosed. The common mode transient reduction circuit includes a delay circuit, coupled between the common bias voltage and the main amplifier, that reduces a magnitude of the main amplifier's common mode voltage output transient when the common bias voltage is changed. In an advantageous embodiment, the delay circuit includes a resistance and a capacitance.

Abstract: A preamplifier circuit of a preamp configured for measuring microwave noise of a magnetoresistive element biased by a pair of current sources is disclosed. In a preferred embodiment, the preamplifier circuit includes a differential amplifier disabled from the preamplifier circuit by a amplifier bypass switch, one of the pair bias current sources disabled from the preamplifier circuit and referenced to ground by a current bypass switch, a test point communicating with the amplifier bypass switch providing single ended access to the biased magnetoresistive element for measuring the microwave noise of the biased magnetoresistive element relative to the ground reference and a ground point communicating with the ground reference providing the ground reference for measuring the microwave noise of the biased magnetoresistive element.

Abstract: A method and apparatus for providing quadrature biasing for coupled-pair circuits. A QBCP-circuit for quadrature amplifiers provides a new input common-mode sense point that separates the inputs for the differential-and-common mode feedback-control loops. The QBCP circuit biases all four transistors equivalently and reduces the feedback-loop interaction, thereby simplifying the bias control system and improves the voltage-transfer frequency-response performance.

Abstract: A method and apparatus for providing matched differential MR biasing and pre-amplification. Tightly matched and well centered low-level MR bias voltage is provided directly to the sensing element for controlled input-impedance differential pre-amplification without common-mode voltage level control with loops.

Abstract: A magnetic data storage and retrieval system includes a magnetoresistive head, a resistor, a preamplifier circuit, a voltage measurement circuit, and a resistance calculation circuit. The preamplifier circuit is operably coupled to the magnetoresistive head and the resistor, and applies a first current to the magnetoresistive head and a second current to the resistor. The voltage measurement circuit measures a first voltage across the magnetoresistive head and a second voltage across the resistor. The resistance calculation circuit calculates a resistance of the magnetoresistive head based upon the first and second voltages.

Abstract: A process that ensures the destruction of data files a user wishes to completely erase from a storage medium, such as a hard drive or removable disk. A system administrator can select a quantity of and pattern to be used in overwrites of the data file so that no one can recover the data from the storage medium. In embodiments, a graphical user interface (GUI) can be provided to allow user triggering of and parameter setting for the process. The GUI can be implemented at a device in which the storage medium is a component or can be implemented in a device driver GUI on a personal computer in communication with the device.

Abstract: An impedance controlling circuit (152) is connected across an MR head (42) and has two current paths, each including a control transistor (154,156), a current path resistor (160,158), and a biasing circuit (162,164) in series. Each side of the MR head 42 is connected between a respective one of the current path resistors (158,160) and the biasing circuits (162,168). A shunt resistor (170) is connected between the control transistors (154,156) and the current path resistors (158,160) in each of the current paths. When the control transistors (154,156) are not conducting, the current path resistors (158,160) and the shunt resistor (170) shunt the MR head (42).

Abstract: The present invention provides a method and apparatus for performing automated spin valve combined pinned layer reset and hard bias initialization at the head gimbal assembly level. The reset combines a current pulse with an assisting magnetic field. The pinned layer reset and hard bias initialization is automated and performed by a single tool at the head gimbal assembly level to increase manufacturing throughput.

Abstract: A method and apparatus for preventing an adjacent track erase effect due to a magnetic head. In the method, a write command is received, an ambient temperature of a hard disc drive is measured, and whether the ambient temperature exceeds a threshold temperature is determined. If the ambient temperature exceeds the threshold temperature, the intensity of a write current is adjusted according to the position of a magnetic head on the hard disc drive. If an overshooting value of the write current exceeds a predetermined steady-state value, the overshooting value of the write current is adjusted. Applying the write current having the intensity and the overshooting value adjusted to the magnetic head. An algorithm having writing intervals can also be used in a hard disc drive. Thus, a writing field can be minimized and made suitable for variations in the temperature of the hard disc drive and coercivity of a magnetic disc so that an adjacent track erase effect can be reduced.

Abstract: A differential circuit to read differential data from a disk by a voltage bias includes a read circuit having a read circuit pole to read the differential data from the disk by maintaining the voltage bias and a feedback circuit having a feedback pole to sense deviations in the voltage and to adjust the voltage in response to the deviations. The read circuit pole is separated from the feedback pole in frequency.

Abstract: A differential circuit to read differential data from a disk by a current bias on a plurality of read heads includes a read circuit to read the differential data from the disk by maintaining the current bias. The current is below a maximum current of a read head having the lowest maximum voltage of said plurality of read heads.

Abstract: An apparatus for providing a read signal at an output locus for access by an information processing device receives an input signal containing the information; the apparatus includes: (a) a read signal control unit receiving the input signal at a control unit input locus; the control unit is coupled with the output locus and controls the read signal; (b) a plurality of switches; and (c) a plurality of bias arrays coupled with the switches. A first bias array set cooperates with the plurality of switches in a first orientation to couple the first bias array set with the control unit to establish a first operational mode. A second bias array set cooperates with the plurality of switches in a second orientation to couple the second bias array set with the control unit to establish a second operational mode.

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: In a production process of an MR head using the tunnel junction film basically consisting of a free layer, a barrier layer, and a pinned layer, the resistance between the free layer and the pined layer reduced beforehand and increased afterward up to a resistance value necessary when actually used. While the resistance between the free layer and the pinned layer is low, current can easily flow, suppressing charge up, thus preventing insulation destruction of the barrier layer. This significantly increases a production yield of a recording/reproduction head using a ferromagnetic tunnel junction element.

Abstract: A magnetoresistive sensor includes a magnetoresistive element and equipment which generates a magnetic field in the magnetoresistive element thereby inducing a biasing magnetic field in the element, where the magnetoresistive element comprises a high electron mobility semiconductor and electrodes which are connected to the semiconductor. If it is an insulator, the equipment, which generates the biasing magnetic field and supplies it to the magnetoresistive element, may contact directly to the magnetoresistive element. If it is a conductor, an insulating separation layer must be set between the equipment and the element. A magnetoresistive element is representatively Corbino disk type or a bar type magnetoresistive element. Another candidate of the magnetoresistive element is an element consisting of a high electron mobility semiconductor, a pair of electrodes which make a current path in the high electron mobility semiconductor, and another pair of electrodes to detect the induced voltage by the current.

Abstract: A recording apparatus of a tape-shaped magnetic recording medium includes a transfer unit, a recording head, a signal-processing unit and a control unit. The transfer unit transfers a tape-shaped magnetic recording medium having an anisotropic property oblique with respect to the thickness direction in a forward or reversed direction. The recording head is positioned in such a way that a recording track is formed on the traveling tape-shaped magnetic recording medium, which is transferred by the transfer unit, in a direction parallel to the transfer direction of the tape-shaped magnetic recording medium. Connected to the recording head, the signal-processing unit receives a signal to be recorded onto the tape-shaped magnetic recording medium. The signal-processing unit then carries out signal processing required for an operation to write the signal to be recorded onto the tape-shaped magnetic recording medium.

Abstract: In a portable data erasing device, to prevent data leaks from magnetic disk devices to be disposed, data is erased by a simple operation. The data erasing device using a magnetic field generated by permanent magnets to erase data comprises a sliding tray, a main body and a swinging tray. The sliding tray is movable into and out from the main body, two permanent magnets, adjacently arranged so that the north and south poles thereof have mutually attracting polarities, are attached to the front end of the sliding tray. One end of the swinging tray is fixed to the upper surface of the main body by a shaft, so that a magnetic disk device can be mounted and swung on top of the main body. While the sliding tray is extracted stepwise from the main body, the magnetic disk device can be swung, and data on the magnetic disks erased.

Abstract: A system and method provide overshoot protection to facilitate driving a load by output circuitry in response to a transition from a first operating mode to a second operating mode. The overshoot protection occurs by masking an input bias from biasing the output circuitry for an initial part of the second operating mode based on a transition to the second operating mode, and then allowing the input bias to bias the output circuitry in a desired manner in a subsequent part of the second operating mode.

Abstract: A differential circuit to read differential data from a disk by a voltage bias includes a read circuit to read the differential data from the disk by maintaining the voltage bias by a first transistor and a second transistor, the first transistor being positioned in a first current path to maintain a first current and the second transistor being positioned in a second current path to maintain a second current. The first current is approximately equal to the second current.

Abstract: A write output driver with internal programmable pull-up resistive devices is disclosed. The write output driver provides an integrated output driver circuit configurable to provide near end transmission line termination. The output driver is configured to provide transmission of a high-speed signal with increased frequencies over prior output drivers. The output impedance of the output driver is programmable and maintained substantially constant, despite ambient fluctuations. An internal bias signal generator is provided to control the impedance of the output driver.

Abstract: Disclosed herein is an apparatus and method of calibrating the parameters of a Viterbi detector 138 in which each branch metric is calculated based on noise statistics that depend on the signal hypothesis corresponding to the branch. An offline algorithm for calculating the parameters of data-dependent noise predictive filters 304A-D is presented which has two phases: a noise statistics estimation or training phase, and a filter calculation phase. During the training phase, products of pairs of noise samples are accumulated in order to estimate the noise correlations. Further, the results of the training phase are used to estimate how wide (in bits) the noise correlation accumulation registers need to be.

Abstract: A write driver circuit selectively provides a write current through a write head in first and second opposite directions. The write driver circuit is connected to the write head through an interconnect. The write driver circuit provides an incident write current signal through the interconnect to the write head, and also provides a reflection cancellation signal through the interconnect to the write head. In an exemplary embodiment, the incident write current signal is provided by providing an incident voltage signal across the write head, and the reflection cancellation signal is provided by providing a reflection cancellation voltage signal across the write head. In an exemplary embodiment, the reflection cancellation signal is a delayed and filtered version of the incident write current signal that cancels a reflected signal that is reflected at the interface between the interconnect and the write head due to impedance mismatching.

Abstract: Apparatus and method for transferring data in a disc drive data handling system. A read/write head having separate write and read elements is used to write data to and transduce data from a disc recording surface. A preamplifier driver circuit applies write currents to the write element to write data to the recording surface and to apply a first read bias signal of selected, nonzero magnitude to the read element to transduce data from the recording surface. In response to the assertion of a write gate signal, the preamplifier driver circuit generates a second read bias signal of selected, nonzero magnitude and applies the second read bias signal to the read element while applying the write currents to the write element. This reduces the potential for damage to the read element due to cross-talk noise induced in the read bias signal from magnetic coupling between the read and write elements.

Abstract: A magnetic detector includes a moving body which is multipole-magnetized and which is rotated synchronously with a rotational axis; a magnetic resistance element for detecting a change in magnetic field of the rotating moving body; a processing circuit portion for outputting a signal corresponding to the multipole magnetization of the moving body in accordance with the change in resistance value of the magnetic resistance element due to the change in magnetic field; and a magnet for applying a bias magnetic field to the magnetic resistance element.

Abstract: A method to erase a magnetic tape, where the magnetic tape is first mounted in a magnetic tape in a tape drive, where that magnetic tape includes a physical beginning of tape (“PBOT”), a physical end of tape (“PEOT”), and information written thereon between the PBOT and the PEOT. The method then establishes one or more critical areas located on the magnetic tape, attempts to erase the information, and determines if each of the one or more critical areas have been erased. In the event each of said one or more critical areas have not been erased, Applicants' method provides an error message.

Abstract: A plurality of redundant sets of servo data are recorded on a magnetic hard disk. The set meeting a predetermine criteria is employed when the hard disk is assembled into a hard disk drive. The determination of which set has the criteria may be conducted by the disk drive itself. The criteria may include a determination the set of servo data having meeting a minimum quality criteria or the fewest errors. The criteria may include a selection of a set of servo data having a specific pattern where the prerecorded sets may comprise a differing servo patterns that may be used by disk drives requiring specific servo patterns. The servo data are printed onto the hard disk by means of a stamper or mask having all the sets of servo data.

Abstract: Magneto-resistive (MR) head pre-amplifiers for single polarity power supply applications are presented. An exemplary pre-amplifier includes a bias network coupled to first and second input terminals of the pre-amplifier, the input terminals for receiving signals corresponding to variations in magnetic fields from an MR head. At least one gain stage having first and second input terminals and first and second output terminals for amplifying the received signals is included. A pair of coupling capacitors, each capacitor being connected between a respective input terminal of the pre-amplifier and a corresponding respective input terminal of the at least one gain stage, are further included in the pre-amplifier design. Finally, the exemplary pre-amplifier includes a pair of feedback capacitors, each capacitor being connected between respective input and output terminals of the at least one gain stage. The pre-amplifier is powered by a single polarity power supply.

Abstract: A disk drive system including a write circuit for controlling current through a magnetic write head includes an H-switch circuit and a pulse-mode power supply circuit. The H-switch circuit controls direction of current through the magnetic write head. The pulse-mode power supply circuit is connected to the H-switch circuit for providing a higher voltage pulse at a beginning of a switching event of the H-switch circuit to accelerate a change in direction of current through the write head, followed by a lower voltage until a next switching event.

Abstract: A bias circuit for a magneto-resistive head having a bias current output circuit for flowing a bias current through a magneto-resistive head, and a feedback circuit for controlling the bias current from a bias current output circuit by detecting voltage variation across the magneto-resistive head so as a voltage across the magneto-resistive head to be a predetermined value, comprises a regulating circuit for regulating an operation of the bias current output circuit in the bias current output circuit, a control circuit for the regulating circuit for controlling the regulating circuit to be in a predetermined condition, and a switching circuit for switching a read/write condition for activating the control circuit for the regulating circuit in a non-read condition of the magneto-resistive head. The regulating circuit includes an oscillation suppressing capacitor; and the control circuit for the regulating circuit is a charging circuit for the oscillation suppressing capacitor.

Abstract: A method and apparatus for running an analog portion (162) of a read/write channel (108) from a highly regulated power supply (260). The apparatus includes an analog portion (162), a clock synthesizer (154), and a highly regulated power supply (260) connected to the analog portion (162) and the clock synthesizer (154). The analog portion (162) and the clock synthesizer (154) both comprise high voltage transistors which operate in a first voltage range and low voltage transistors which operate in a second voltage range, wherein the first voltage range is within the second voltage range. The highly regulated power supply (260) supplies power that is within the first voltage range to the analog portion (162) and the clock synthesizer (154). The method includes generating power that is within the first voltage range using the highly regulated power supply (260), and supplying the power to the analog portion (162) and the clock synthesizer (154).

Abstract: A guarantee processing method guarantees the data of an adjacent track in the case of a write fault, and guarantees the data only when there is the possibility of an off track write at a write fault. Even if a write fault is detected or if an offset read retry succeeded, a rewrite for guaranteeing an adjacent track is not executed immediately, but the possibility of an off track write is judged by the movement of the head, and if there is the possibility of an off track write, the sector which became difficult to be read due to the off track write is detected, and only that sector is rewritten.

Abstract: A data eraser for erasing data recorded on a data recording medium, where data recorded on the recording medium can be erased in a short time period. Data produced in the CPU of the controller is stored in the memory as a random unit data; the unit data are repeatedly and continuously written in the memory to constitute record data for erasing purpose; the thus produced recording data for erasing are written on the hard disc to erase the data memorized in the hard disc. Since the time for producing random data, which normally takes time, is shortened, the time for proceeding as a whole can be shortened.

Abstract: A sampled amplitude read channel incorporated within a magnetic disk storage system for reading data recorded tracks on a magnetic medium, where the data comprises user data sectors recorded at varying data rates across a plurality of predefined zones and embedded servo data sectors recorded at the same data rate across the zones. The read channel comprises a timing recovery component for synchronous sampling of a read signal from a magnetic read head positioned over the magnetic medium, a gain control component for adjusting the amplitude of the read signal, and a DC offset component for canceling a DC offset in the read signal. These components are dynamically configured to operate according to whether the read channel is processing user data or embedded servo data.

Abstract: A system, method and computer program product provide an annealing process for setting a magnetization condition of a read head. An amount of heat for stabilizing magnetization condition of a read head is calculated. A width and amplitude of a voltage pulse that generates the calculated amount of heat in the read head are calculated. A voltage pulse of the calculated width and amplitude is applied to the read head for generating Joule heating in the read head. The width of the voltage pulse is less than one second.

Abstract: The present invention uses temperature readings obtained aperiodically, on demand. Rather than merely obtaining temperature readings on each expiration of a fixed timer, operating parameters are updated in response to a fault detected in the data path. Data handling systems of the present invention each include at least one data path having a thermal range within which it operates best. Applicant notes that some “key” operating parameters typically have a substantial effect on this thermal range. Temperature sensors positioned near the transducers provide a temperature reading to control circuits, which update “key” operating parameter values in response to indications of faults in a primary data path. This reduces the need for more frequent temperature monitoring and calculation-intensive recalibration.

Abstract: The present invention may be regarded as a disk drive comprising a disk having a plurality of data tracks, each data track comprising a plurality of sectors. A sync mark detector detects a sync mark pattern in a sector, wherein when the sync mark pattern is detected a sync mark detect signal and a polarity signal are generated. The polarity signal represents an expected polarity of pulses in a read signal representing data stored in the sector, wherein the polarity signal enhances the detection of an estimated data sequence from the read signal.

Abstract: An MR head bias circuit (60) in a preamplifier includes a balanced driving circuit (62,64) for connection to the MR head (12) at respective first (66) and second (68) output nodes and impedance matching elements (72,74) to match an output impedance at each output node (66,68) to each other. The impedance matching elements (72,74) may match an output impedance at each output node (66,68) to make them substantially the same.

Abstract: A reproducing circuit for a MR head is proposed, wherein a MR head is interposed between a pair of current source circuits and a feedback amplifier is provided for controlling the current of the pair of the current source circuits so that a terminal voltage of the MR head becomes a predetermined value. Reproduced output from the MR head is derived from an amplifier having balanced input terminals for canceling noises and ripple components included in a power source.

Abstract: A disk driver writer precompensation system modulates the write current waveform based on a pattern of data bits magnetically recorded on a medium in order to adjust the timing of magnetic transitions recorded on the medium.