Abstract: A detection circuit or a perpendicular recording system includes a channel circuit to amplify the read data signal. A transient detector generates a transient detect signal. A first path and a second path are coupled to an output of the channel circuit. The first path includes a first data detector that generates a first detected data signal in response to detecting data in the read data signal. A second path includes a series connected combination of a data filter and a second data detector. The filter generates a filtered data signal in which low frequency components of the read data signal are attenuated. The second data detector generates a second detected data signal in response to detecting data in the filtered data signal. Either the first detected data signal or the second detected data signal is coupled to a data processor based on whether a transient is detected.

Abstract: A method and apparatus for detecting a high flying condition of a transducer head in a computer disk drive is provided. The method and apparatus allow the detection of high fly write events that occur over one or a small number of data sectors. In addition, the present invention provides a method and apparatus for detecting high fly write events with a great deal of sensitivity. The method and apparatus of the present invention provide quick response and high sensitivity by monitoring the strength of a signal derived from data written to the disk, and signaling a high fly write event if the monitored signal strength in connection with a particular piece of data is less than a stored high fly write number corresponding to that piece of data by a predetermined amount.

Abstract: A high-speed transmission circuit includes an inductive head. The high-speed transmission circuit also includes a non-uniform transmission line having a variable characteristic impedance. The non-uniform transmission line is coupled between the inductive head and an endpoint node such that pulses are conducted over the non-uniform transmission line. The variable characteristic impedance is greater near the inductive head than near the endpoint node.

Abstract: A magnetic recording process generally including the steps of determining an initial magnetization direction of a magnetic recording medium, and selectively applying a magnetic field to the magnetic recording medium along an axis substantially perpendicular to an axis of the initial magnetization direction of the recording medium. The magnetic field is selectively applied for a period of time sufficient to switch the magnetization of the magnetic recording medium from its initial magnetization direction to a final magnetization direction substantially anti-parallel to the initial magnetization direction. Typically, the initial and final magnetization directions will be along an easy axis of magnetization of the magnetic recording medium.

Abstract: A head suspension assembly having a magnetic head, an arm which is supported so as to rotate, a suspension having one end which is fixed to an end of the arm and an other end which mounts the magnetic head, a nonvolatile memory which is mounted on the suspension assembly, and stores control parameters of the magnetic head, a connecting terminal which is mounted to the arm, and a signal transmission line which electrically connects the connecting terminal to the nonvolatile memory and the magnetic head. The connecting terminal enables transmission of signals at least one of to and from the head suspension assembly, the nonvolatile memory and the magnetic head.

Abstract: A motor bridge driver interlace, implemented in an ASIC using cost-efficient CMOS technology, is designed to control four external MOS power transistors in a H-bridge configuration for DC-motor driving to achieve accurate and fast switching. Main components of the interface are a charge pump for generating the control voltage for the high-side N-channel MOS transistors, high-side (HSD) circuits, low-side (LSD) circuits and a complex digital interlace for supplying the control signals in a programmable timing scheme. A “strong” charge pump is used to realize a simple CMOS switch to steer the output to the high-side transistors of said H-bridge. The motor bridge is connected to the battery supply by an additional N-channel MOS transistor to implement a reverse supply protection.

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 disk drive is disclosed which has a facility to perform a pinning reset operation on a GMR read element included in a head if a read retry operation fails to achieve recovery from a read error. When a bias and write currents are supplied to the head, a CPU of the disk drive determines an optimum bias and write currents on the basis of a temperature measured value of the GMR read element.

Abstract: The invention includes a testing method which may be applied to at least one writer in a disk drive during the self-test phase to generate write parameters, focused on the Over Shoot Control (OSC) of the write current parameter to improve the reliability of write operations by that writer. The Minimum OSC is used for write operations in normal temperatures. The Optimum OSC is used for a first lower temperature range, preferably between essentially 15° Centigrade and essentially 5° Centigrade. The Maximum OSC is preferred below essentially 5° C. The Minimum OSC should preferably guarantee both an Adjacent Track Write (ATW) criteria, as well as guarantee a Write Induced Instability (WII) criteria. The invention includes the write parameter collection, as well as the disk drive containing the generated write parameter collection.

Abstract: A data reader derives a signal on reading a data holding medium. The data reader has processing circuitry to process the signal. The processing circuitry includes a filter having a variable cut-off frequency, a velocity signal generator that produces a signal corresponding to the velocity of the data holding medium, and a processor. The reads the velocity signal and sets the filter cut-off frequency. Calibration data derived during a calibration operation of only the particular data reader determines the filter cut-off frequency for different speeds of the medium during normal read operations of the medium.

Abstract: In a disk drive of the perpendicular magnetic recording method, there is disclosed a servo data encoding method for recording servo data with a particularly low frequency on a disk. The coded data of the servo data by this method is coded with DC free code which is capable of suppressing a direct current component of the read signal waveform. As a consequence, in the case where signal processing is conducted in the read/write channel by the cut-off low frequency characteristic, a waveform distortion can be suppressed which is generated in the read signal waveform by the cut-off low frequency characteristic. Consequently, an improvement in the read error rate in the read/write channel can be realized.

Abstract: A magnetic storage system includes a preamplifier writer that selectively drives a write current through a write head to write data to a magnetic storage medium. The write current generated by the preamplifier writer has a boost stage and a settling stage. An impedance changing circuit communicates with the preamplifier writer and the write head and provides a lower resistance value during the boost stage and a higher resistance value during the settling stage.

Abstract: A recording system of a magnetic tape drive is operated to cause one separate set of write heads to write data discontinuously to magnetic tape as received, and to save the data, and, during the same operation, to cause another separate set of write heads to rewrite data to magnetic tape in a continuous arrangement. The writing may be in parallel and simultaneous. Thus, during the same operation, and at the same time, the separate sets of the plurality of write heads, temporarily write the received data to magnetic tape so that the sender can erase its copy, and rewrite the saved data to the magnetic tape in a permanent arrangement, without waiting to complete first writing received data, to complete subsequently rewriting the data, and repeating.

Abstract: A write driver circuit for driving a magnetic head applicable to a variety of magnetic heads or magnetic storage media is disclosed. The circuit includes a write current generating section for generating plural types of write current for magnetizing a predetermined area of a magnetic storage medium in a predetermined direction; a switching signal generating section for generating a switching signal for switching among the write currents; a switching section for changing the direction of magnetization through the magnetic head by switching among the write currents based on the switching signal; and an overshoot current generating section for generating an overshoot current for instantaneously increasing the write current when the direction of magnetization is changed by the switching section; wherein the circuit further includes an overshoot current generation signal producing section, and is designed so that the overshoot current is generated based on an overshoot current generation signal produced thereby.

Abstract: A digital servo system of an optical disk drive with a calibrated inverse non-linearity function is disclosed. A look-up table is determined, for example, with a focus error signal gain corresponding with a focus error signal offset so that the response of the focus servo system is substantially linear. Additionally, the look-up table can include tracking error signal gain, tracking error signal offset, or tracking loop gain parameters corresponding with the focus error signal offset.

Abstract: There is disclosed a disk drive which can appropriately execute a gain control of an AGC amplifier included in a read channel for each zone on a disk. A CPU refers to table information stored in a memory, and reads initial gain data corresponding to the zone during switching of the zone as a read object. The CPU sets the read initial gain data into the AGC amplifier.

Abstract: A voltage regulator includes an output node and first and second regulator circuits. The first regulator circuit generates a first regulated voltage on the output node when a supply voltage equals or exceeds a predetermined threshold, and the second regulator circuit generates a second regulated voltage on the output node when the supply voltage is less than the predetermined threshold.

Abstract: A method and apparatus for reducing the servo position error signal non-linearity during self-servo writing irrespective of the head width is disclosed. Write current of each head is modified based upon the head width. The write width for all heads is measured and a write current for each head in a disk drive is adjusted toward a predetermined level. A mean track propagation width for the disk drive is determined, wherein the predetermined level establishes the determined mean track propagation. A mean head width is determined and the write current for each head is adjusted by applying a higher write current to heads smaller than the mean head width and a lower write current to heads wider than the mean head width. Optimal performance is achieved using the adjusted write currents. The measuring of the head width is repeated and the write current is adjusted until a track propagation for the disk drive meets a predetermined criteria.

Abstract: A circuit for measuring signal output of a transducer includes an amplifier having a differential input and a single ended output referenced to a fixed potential. One transducer terminal is coupled through a source follower to an input terminal of the differential input and the other transducer terminal is coupled through a source follower and a resistive element to the other input terminal of the differential input whereby the transducer terminals are isolated from the fixed potential. A voltage to current converter converts the voltage at the single ended output to an output current that is applied to an input branch of a current mirror. A first output branch of the current mirror supplies a current equal to the converter output current to one terminal of the differential input. A second output branch of the current mirror supplies a current equal to the converter output current to the other terminal of the differential input.

Abstract: A tape drive and method of identifying write velocity during reading are provided. When a track is being read, a lead-in code of the data signal is processed prior to determining the data stream. The lead-in code identifies the velocity with which the track data were written. The equalization/detection channel is adjusted based on the identified velocity to compensate for write channel transfer function variation. The lead-in code is coded in a way that is reasonably immune to write channel transfer function variation such that the lead-in code is comprehended prior to adjusting the equalization/detection channel.

Abstract: A hard disk drive and process of controlling the drive by adjusting disk drive parameters in accordance with ambient temperature. Various parameters affected by thermal variation are controlled to automatically adjust those values in order to compensate for changes in ambient temperature when an environment where a hard disk drive is installed changes, thereby allowing the hard disk drive to continuously operate with optimal performance. Those parameter, which are sensitive to the temperature of a hard disk drive, can be modified or controlled using the relationship therebetween in accordance with the current ambient temperature, thereby preventing any deterioration of the performance of the hard disk drive, even when temperature at the burn-in process and the current ambient temperature are different from each other.

Abstract: Magneto-Resistive (MR) head read/write channel (400) provides timer (421), detector (433) and amplifier (432) to reduce the amount of time required to transition from read mode to write mode. Controller (410) issues the write command (WGATE) to signal a pending mode change from read to write mode. While read/write channel (400) remains in read mode, timer (421) begins a configurable countdown sequence, which allows Arm Electronics (430), except for a final output stage of amplifier (432), to power up in preparation for write mode. Once timer (421) has reached terminal count, signal (CHWGATE) is de-asserted, which causes write channel (422) to warm up. After warm up, write channel (422) writes serial data (WRITE DATA) to detector (433). Still in read mode, detector (433) detects the presence of WRITE DATA from write channel (422) and asserts signal (AEWGATE).

Abstract: The invention provides a method insuring that each read channel optimization step is controllable in terms of quality divergence, that a systematic response can be made which can be readily automated. The method is applicable to a pre-existing read channel optimization (RCO) script. The method includes the following operations. Acquiring a first quality measure and a first parameter list. Performing the pre-existing RCO script creating a second quality measure and a second parameter list based upon the first parameter list. Convergence processing the first and second quality measures and parameter lists.

Abstract: A device for amplifying and converting current signals into voltage signals for processing The current signals are delivered by sensors, e.g. optical transducers, magnetical heads. The current signals are first amplified using a current to current amplifier, the amplified current signals are then transported using electrical conductors and eventually amplified using a current to voltage amplifier. The invention may find application in consumer electronic devices, cars, planes, industrial machines.

Abstract: In recording information, meta data defined in SMPTE 298M and 335M, buried in video and audio material signals to be recorded to a magnetic tape (30) are extracted, the thus extracted meta data or meta data generated from information other than the material signals, are written to a contactless memory tag (37), whereby it is made possible to acquire meta data about material signals recorded in a recording medium without actual reading of the material signals in the recording medium and use the meta data for search, validation, etc.

Abstract: A magnetic storage device equipped with a write driver circuit is provided. This magnetic storage device includes: four current sources each provided at a corresponding one of the four sides of an “H-bridge” circuit; a magnetic head provided at the bridging part of the “H-bridge” circuit; and a series circuit including capacitors and terminating resistors. A separate series circuit is provided between the ground and each corresponding one of the connection points of the bridging part and the four sides of the “H-bridge” circuit. With this magnetic storage device, impedance matching can be easily performed. Also, a smaller circuit size can be realized, and accordingly, the power consumption can be reduced. Furthermore, desired recording can be performed at a high transfer rate.

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 that a voltage across the magneto-resistive head becomes a predetermined value. The bias current output circuit comprises a regulating circuit for regulating an operation of the bias current output circuit in the bias current output circuit, a control 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: The present invention discloses an impedance matched low noise amplifier circuit (10) comprising a serially coupled first resistor (R1) and first transistor (R0), a serially coupled second resistor (R2) and second transistor (R1), a resistive sensor (RMR) coupled to the first transistor (R0) and the second transistor (R1), wherein the first resistor (R1) and the second resistor (R2) are coupled, and a transconductance feedback block (GM) coupled to the resistive sensor (RMR) and to the serially coupled resistors (R1, R2) and transistors (R0, R1).

Abstract: The invention relates to a method of reading of magnetic information. In an example embodiment, a read head includes a magneto-resistive rod polarized with an electrical signal. The magneto-resistive rod supplies a data signal whose variations are representative of magnetic-field variations to which the read head is exposed. Included in the embodiment, there is a compression of the data signal triggered when a thermal asperity is detected.

Abstract: A first amplifier which amplifiers a faint read signal read by a head is connected to a second amplifier which further amplifiers the read signal amplified by the first amplifier, via a signal line. The signal line is used to transmit the read signal from the first amplifier to the second amplifier, and also to transmit a control signal from the second amplifier to the first amplifier. On the basis of, for example, a point in time at which a servo mark is detected from servo data, a control unit sets a period of time in which the transmission of the control signal from the second amplifier to the first amplifier is permitted, so that it does not overlap a period of time in which the servo data is read.

Abstract: A method and apparatus are provided for implementing enhanced data channel performance using a read sample buffer in a direct access storage device (DASD). Disk data is read and stored in the read sample buffer. When a data recovery procedure (DRP) starts, the stored disk read data in the read sample buffer is detected. Error correction code (ECC) checking of the detected sample buffer disk data is performed to identify correctly recovered data. Using the disk read data stored in the read sample buffer enables data recovery without identification of a sync word. Also using the disk read data stored in the read sample buffer enables data recovery with changed channel data detection settings to recover the data. The read sample buffer can be used for accumulating read disk data from more than one read operation so that at least some channel noise is averaged out.

Abstract: Method and apparatus for recording data on a magnetic recording medium and writing data to a computer bus in which the data is divided into words of a predetermined length, a signal is generated for each data word, having an amplitude which is representative of the value of the data word, and this signal is then recorded to the magnetic recording medium or written to the computer bus. Complementary method and apparatus is provided for reading the data from the magnetic recording medium and the computer bus.

Abstract: A magnetic recording apparatus suitable for high-density and high-frequency magnetic recording includes a recording head to the coil of which a recording current is supplied, the recording current having a waveform such that the conducting time length is shorter than the time length of a recording pattern.

Abstract: In order to solve a problem that it takes a long time to shift from a write mode to a read mode when there is a cross talk of an output signal of a recording head to a reproducing amplifier side, there is provided a reproducing amplifier including an amplifier circuit portion having a differential pair of transistors is provided with a switching circuit comprised of switches connected with resistors, which supply a bias voltage to each base of the differential pair of transistors, respectively in parallel. The switching circuit turns on for a write mode period and for a fixed period after a change from the write mode to a read mode to decrease the input impedance of the reproducing amplifier for the periods.

Abstract: A write driver apparatus and corresponding method for an inductive head element (20) in a magnetic storage medium, such as a hard disk drive, having an H-bridge type circuit (10) which is capable of driving a current through the inductive head element (20) and having a boost circuit (250, 260) which is coupled with the H-bridge (10) and which is operable for delivering another current during a predetermined period to the head element (20), wherein a sum of the currents provides the write current for the head element (20) of the hard disk drive. Further, a resistive element (210, 320, 330) is selectively coupled with the head element (20) for providing impedance matching in which the resistive element (210, 320, 330) is decoupled from the head element (20) during delivery of the current from the boost circuit (250, 260).

Abstract: In an apparatus for recording and regenerating data, a pass metric is calculated based on a likelihood converted from a previous calculation result iteratively until all pass metrics of the same data recorded many times on a recording medium are calculated, and then data recorded on the recording medium is decoded.

Abstract: A main controller controls the current in an overshoot part included in the write current supplied from a write driver to a head in accordance with write data via an overshoot controller in accordance with the temperature detected by a temperature sensor.

Abstract: A repeatable run-out (RRO) detector employs one or more digital interpolators to interpolate asynchronous sample values representing an RRO address mark (AM) and RRO data, an asynchronous maximum-likelihood (AML) detector to detect the RRO AM, and a RRO data decoder to decode the RRO data. The AML detector employs an AML algorithm, such as a Viterbi algorithm, to detect the series of peaks of the RRO AM based on detection of the entire sequence of observed peaks. AML detection selects one of either the asynchronous or interpolated sample sequences that are closest in distance to the ideal RRO AM sample sequence. Once the RRO AM is detected, the AML detector provides a RRO AM found signal as well as the selected one of the sample sequences having the best phase for detecting and decoding the RRO data.

Abstract: A circuit to detect pin layer reversal including an input circuit to receive an input signal having a first portion to indicate a pin layer reversal and having a second portion to indicate a servo sync mark, a first servo sync mark detector for detecting a positive servo sync mark from the input signal, a second servo sync mark detector for detecting a negative servo sync mark from the input signal, and a circuit responsive to the positive servo sync mark and the negative servo sync mark to generate a signal to indicate if the servo sync mark has been reversed and to generate a signal to indicate the pin layer reversal.

Abstract: A method of tuning a bias parameter for a magnetoresistive head in a data storage system includes the step of identifying, from multiple possible bias parameter values, a smallest bias parameter value for the magnetoresistive head which both maintains a bit error rate above a predetermined threshold bit error rate, and which satisfies a second criteria. The method then includes the step of setting an operational bias parameter value for the magnetoresistive head to the identified smallest bias parameter value. Also disclosed are data storage systems, or controllers which are connectable to or included with data storage systems, configured to implement the methods.

Abstract: A write driver for use with a magnetic recording head includes a photoconductive switch that is positioned adjacent a magnetic recording head for switching current waveforms. Both light and a DC voltage are applied to the photoconductive switch to switch the applied current waveforms. The write driver further includes means for writing to a storage medium in response to current waveforms switched by the photoconductive switch. The write driver may also include a suspension that supports at least one photoconductive switch, DC conductors for supplying a DC voltage, means for supplying light, and recording head means for writing to a storage medium.

Abstract: A system and method for recovering from write errors during writing of a moving storage medium suspend write current while allowing the storage medium to continue moving. The system and method continue to format data for writing while the write current is suspended and resequence the data for subsequent storage. Information is recorded to distinguish previously written data from current data with error correction pointers adjusted accordingly. Write errors may be detected in a track following streaming tape system based on data errors from a read back check or based on positioning errors of a read/write head servo system, for example. By allowing the storage medium to continue moving through the error event, the system and method improve speed, capacity utilization, and throughput of the storage and retrieval process.

Abstract: A system and method for decoding magnetic media. Parallel decoders, each with a different equalization magnitude, are used to decode a read signal. A Viterbi metric is used to determine the direction and magnitude of equalization shift that best compensates for a systematic separation, such as pole tip recession. If optimal equalization has changed, the equalization coefficients of the decoders is shifted to compensate.

Abstract: A disk drive is disclosed comprising a plurality of disk surfaces and a plurality of respective heads actuated radially over the disk surfaces. Each disk surface comprises a plurality of tracks, each track comprising a plurality of data sectors and a plurality of embedded servo sectors, each embedded servo sector comprising a servo sync mark for synchronizing to the embedded servo sector. When the disk drive switches heads, a detection window for detecting the servo sync mark is opened early. An asynchronous gain control algorithm prevents a gain control system from diverging while reading an area of the disk surface preceding the servo sync mark, and a synchronous gain control algorithm maintains a proper gain of the read signal while reading the servo sync mark.

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: A voltage-mode boosting write driver circuit (40) having a pair of voltage boosting PMOS transistor sets (44, 46) coupled to a high current H-switch (42). One set (44) of the boosting PMOS transistors correspondingly pulls output pin HY high, while the other transistor set (46) correspondingly pulls output pin HX high and the other output pin HY low thereby significantly improving the head voltage swing, and also achieving a faster slew rate. Moreover, resistors (R3, R4) of the H-switch are both matched to each other and impedance matched to a flex cable (T0) interconnection impedance, which interconnection is coupled to the thin film head, to thereby eliminate signal reflection such that the write current (Iw) settles quickly with minimum ringing to achieve a high data rate. Moreover, less power dissipation and smaller number of devices used are achieved by making use of existing transient currents of the pre-driver emitter follower stage.

Abstract: A method and apparatus for allowing communication between a stationary circuit and circuitry in motion with respect to the stationary circuit is presented. Communication is achieved and verified by transmitting a clock signal and a control signal in synchronization with the clock signal over separate clock and control transformer channels between the stationary circuit and the moving circuitry.

Abstract: A preamplifier system is provided for use with a magneto-resistive (MR) sensor. Included is an alternating current (AC) coupling module connected to the MR sensor for blocking a direct current (DC) voltage associated with an input signal, and filtering low frequency noise associated with the input signal. Also provided is a gain stage module coupled to the AC coupling module. The gain stage module includes a plurality of cascode field effect transistors (FETs) configured for amplifying the input signal, while reducing intrinsic noise and increasing operational bandwidth. Coupled to the gain stage module is a control circuit for feeding back an output of the gain stage module for bias regulation and disturbance rejection.

Abstract: Devices and methods for generating a magnetic head-specific overshoot current which is combined with an alternating current waveform into a write current used by the magnetic head to store information on a magnetic medium. A processor analyzes the frequency of incoming write data and retrieves from a data table of an overshoot current amplitude and an overshoot current phase. This amplitude and phase information is sent to an overshoot current generator to generate an overshoot current that is responsive to the dynamic impedance properties of a magnetic write head during operation. The data table may have information related to one or many write heads, and the data table may be further subdivided based on additional dynamic characteristics of a write head that may affect the impedance thereof.

Abstract: A digital information reproducing apparatus using rotary heads that reproduces digital information signals recorded on a magnetic tape using magneto resistive heads installed on a rotary drum. The apparatus includes, in the fixed side of the apparatus, a magnetic tape checking circuit that checks the type of the magnetic tape; and a control signal generation circuit that generates a control signal for controlling the gain of a reproduction amplifier circuit; and on the rotary drum, a decoder circuit that identifies the control signal transmitted from the control signal generation circuit. The control signal generation circuit generates the control signal based on a checking result given by the magnetic tape checking circuit, and the decoder circuit identifies the transmitted control signal to control the gain of the reproduction amplifier circuit.