Abstract: The invention is directed to patterned magnetic media for use in magnetic recording and data storage, and various encoding techniques that can be used to magnetically encode data on the patterned media. For example, a patterned magnetic recording medium can include a first set of surface variations and a second set of surface variations. The medium can be conditioned to magnetically expose the surface variations relative to areas between the respective surface variations. Detection of the surface variations in the first set can allow for synchronization of a magnetic drive to the medium. Following such synchronization, the magnetic drive can selectively apply magnetic fields to a second set of surface variations of the patterned magnetic medium to encode data on the patterned magnetic medium.

Abstract: The present invention comprises a pair of circuits (171, 172) within the first stage (100) of an AC signal pre-amplifier. The present invention reduces the current mismatch at the base of the first stage transistors (141, 142, 143, 144) resulting in faster switching times by reducing input stage offset and, hence improving input dynamic range.

Abstract: The present invention provides a semiconductor integrated circuit capable of reducing a circuit area and a magnetic storage device using the same. The circuit in the present invention is provided with a single-stage output transistor for supplying write current to a magnetic head, a current source for outputting reference current of the write current, a diode-connected NMOS transistor for converting the current to gate voltage and having a certain device size ratio to the output transistor, a regulator circuit for transmitting gate voltage of the NMOS transistor and reducing output impedance, and a CMOS circuit for setting power supply voltage to an output of the regulator circuit and controlling the gate voltage of the output transistor. Then, this circuit is applied as a write circuit in a magnetic storage device.

Abstract: A data storage device, data write method, and program to avoid extra power consumption and suppress a write error that may result from voltage variations. To write data onto a magnetic disk, a write circuit generates a write current that is to be supplied to a write head. The write circuit operates on a positive power supply voltage provided by a host computer, and on a negative power supply voltage generated by a programmable DC—DC converter mounted on a hard disk drive's card. The magnitude of the negative power supply voltage generated by the programmable DC—DC converter is varied in accordance with the temperature surrounding the magnetic disk. Further, the magnitude of the negative power supply voltage generated by the programmable DC—DC converter is varied in accordance with the magnitude of the positive power supply voltage supplied from the host computer.

Abstract: A write driver driving a write current through a head connected to the write head by an interconnect. The write driver includes a circuit matching output resistance to the odd characteristic impedance of the interconnect and a voltage boosting circuit. The voltage boosting circuit in connected between a high voltage reference or supply voltage and a low voltage reference, and includes a current source, such as a MOS transistor, connected to the input node of a capacitor. During the overshoot duration, the current source operates at saturation to generate a pulsed current with an amplitude of half the load current. The circuit includes another transistor in series with the current generator between the capacitor and the driver output. A forward bias diode is connected between the capacitor output node and high voltage reference and enters reverse bias during overshoot duration swinging the driver output voltage above supply voltage.

Abstract: The present invention covers circuits to achieve high data rate writing.

Abstract: In order to account for the misplacement of a write element during a servowriting process, the width of the information being written can be varied. In a self-servowriting disk drive, for example, the write current supplied to a read/write head can be adjusted to vary the width of information, such as servo bursts, written by the head. By calibrating the head and determining the misplacement of the head while writing, an edge of a servo burst can be placed in the desired position regardless of the misplacement of the head simply by adjusting the width of the written burst. This description is not intended to be a complete description of, or limit the scope of, the invention. Other features, aspects, and objects of the invention can be obtained from a review of the specification, the figures, and the claims.

Abstract: In a magnetic disk drive, a writing element and its surrounding area thermally expand due to the heat generated by a write head coil. The transient phenomenon of such thermal expansion may invoke the transient phenomenon of inadequate writing capacity, thereby causing a writing error at an early stage of a write operation. Control is provided which increases/decreases either or both the write current to be applied to a write head and the amount of its overshoot on an individual sector basis during a writing sequence.

Abstract: A pre-amplifier, a Thevenin writer and a disk drive employing transistors having a breakdown voltage below a circuitry operating voltage. In one embodiment, the pre-amplifier includes an emitter-follower transistor pair couplable to a power supply and a differential transistor pair, having a collector-emitter breakdown voltage below a voltage of the power supply, that receives current from, and controlled by, the emitter-follower transistor pair.

Abstract: A method and apparatus to control changes in a flying height between a write head and a disk caused by a write current or an overshoot value of a write current are provided. The method comprises: changing a write current or an overshoot value of the write current in relation to a temperature; determining whether the head and the disk surface of a hard disk drive are in contact in relation to changes of the write current or the overshoot value of the write current; and setting the write current and the overshoot value of the write current as a threshold when the head and disk surface are in contact. Accordingly, the magnitude of a write current and the threshold of an overshoot value can be accurately set, and a write current equal to or less than the threshold can be provided when a write operation is performed, thereby providing a reliable write operation.

Abstract: A driver circuit drives a write element for magnetic recording, and permits high speed recording while preventing noise from entering an adjacent read element. An H bridge circuit, which causes a write current to flow, in accordance with a write drive signal, in a write coil of the write element, is provided with an overshoot circuit, in which positive and negative power sources are of the same potential. It makes a flyback voltage vertically symmetrical. Further, a feedback circuit is provided which monitors the voltages at both ends of the write coil, and prevents a variation in the common potential of the write coil. Terminal resistors are further provided to prevent the effects of reflection in a transmission line, and to prevent a change in the write waveform.

Abstract: A method and apparatus providing generalized write pre-compensation is disclosed. The present invention provides multiple phase signals to choose from for provide a shift to received write data to achieve a desired pre-compensation.

Abstract: A method of measuring the degree of thermal pole tip protrusion (TPTP) of a magnetic head and controlling a recording current in consideration of the degree of TPTP, in relation to a hard disk drive includes measuring the rate of errors contained in data by performing writing and reading operations while changing the level of an overshoot current (OSC), detecting a minimum error rate and a maximum error rate while changing a range of the OSC, and determining the degree of TPTP by measuring the difference between the minimum error rate and the error rate at the maximum OSC.

Abstract: A disk drive is disclosed for optimizing write current settings relative to drive operating characteristics and a plurality of ambient temperature readings. Test data is written to and read from the disk to generate quality metrics that are evaluated to generate an optimized write current setting for each ambient temperature reading. In one embodiment, the optimized write current settings are derived during manufacturing and used in-the-field during normal operation. In another embodiment, the optimized write current settings are re-optimized in-the-field to compensate for changes in the drive operating characteristics that occur over time (e.g., environmental changes and electrical and mechanical changes).

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: 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 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 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 write compensation circuit of a recording device includes a first delay portion driven by a first driving voltage, for receiving a clock signal, delaying the clock signal by a first delay time, and outputting the delayed clock signal, and a voltage supplying portion for supplying the first driving voltage to the first delay portion in such a manner that the first delay time is substantially equal to a clock period of the clock signal.

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 high voltage differential amplifier including an input differential pair of low voltage transistors, a sense differential pair of low voltage transistors, first and second high voltage transistors, a low voltage bias transistor, a cascaded pair of low voltage transistors, and an output pair of high voltage transistors. The sense differential pair has a pair of control terminals that detect a common mode voltage of the differential input signal, and establishes a sense node which follows the common mode voltage. The first high voltage device is coupled to the sense node to establish bias node voltage levels which track the common mode voltage, including an output bias node biasing the output pair and a cascade bias node biasing the cascaded pair. In this manner, the terminals of the low voltage devices slide up or down with the common mode voltage and are protected from high voltage levels.

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: 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: An open write head detection circuit is provided comprising a write head driver circuit, a programmable reference voltage source, a comparator and a pulse width filter. The write head driver circuit generates an voltage sense signal. The comparator compares the voltage sense signal with a reference voltage from the programmable reference voltage source and generates a comparator output signal indicative of whether the voltage sense signal is greater than or less than the reference voltage. The comparator output signal is input to the pulse width filter which generates a latched open head signal in response the voltage sense signal being less than the reference level for a predetermined time measured as a programmable number of write clock cycles.

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 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: An apparatus configured according to characteristics for driving a write head to write to a memory device includes: (a) a current directing circuit directing a write current through a first circuit path or a second including the write head in response to a first or second write signal; (b) at least one of: (1) an impedance system for including at least one impedance unit within each of the first and second current paths; and (2) a current system for including at least one circuit element between a locus at each end of said write head and a supply voltage; and (c) a control unit coupled with at least one of the impedance system and the current system for effecting the including for at least one of the impedance system and the current system to effect configuring the apparatus.

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: 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 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 method and system for calibrating the write current of a current mode write driver having a first PFET coupled to a first NFET at a first node connected to a first side of a write head of the write driver, and a second PFET coupled to a second NFET at a second node connected to a second side of the write head. The write driver also defines an INODE where a source of the first NFET is coupled to a source of the second NFET, and the write driver is put in a state where all FET devices are in an off condition. A precision resistor R is connected from the NODE I/O pin of the write driver to a positive potential VDD I/O pin of the write driver, causing a current I1 to flow, where I1=V/R, and V is a voltage across the resistor.

Abstract: A dual mode write driver, such as in a tape or disk drive system, provides both a voltage mode of operation and a current mode of operation by combining the required topology in a write driver circuit. A logic control signal applied to an input to the dual mode write driver causes the circuit to configure for either mode. The write driver has a first PFET (P3) coupled to a first NFET (N1) at a first node connected through a resistor (R1) to a first side of a write head (L1) of the write driver, and a second PFET (P4) coupled to a second NFET (N2) at a second node connected through a resistor (R2) to a second side of the write head. A first voltage mode NFET device is turned on during the voltage mode to connect the sources of the first and second NFET devices to ground.

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 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 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 magnetic head driving circuit includes a main driving circuit symmetrical with respect to a centered recording coil, and at least two pairs of adding circuits, each pair including a positive pulse adding circuit and a negative pulse superposed circuit symmetrical with respect to the centered coil. And, by reversing the direction of the magnetic head coil current, at least one of the adding circuits is made to operate and make it as a magnetic head driving circuit for adding a potential equal to or higher than the power supply, thereby to drive as a sub-driving circuit arranged symmetrically with respect to the centered coil, which promotes the reversal of the magnetic head coil current, and which drives stably with a central potential of the coil at about the disk potential.

Abstract: A method of operating a transducer includes heating a write element by passing a preheat electrical current through a conductive coil of the write element in a manner which produces a substantially zero magnetic flux. The method also includes writing data to a media after heating the write element by passing a write electrical current through the conductive coil in a manner in which produces a net magnetic flux.

Abstract: The invention provides a signal transmission apparatus using a rotary transformer by which a wide bandwidth and a high transfer rate can be used without a significant increase of the cost. The signal transmission apparatus includes a transmission side circuit and a reception side circuit between which a rotary transformer is interposed. A passive element circuit including an inductance element is connected to an output stage of the rotary transformer in parallel to the transformer. The passive element circuit has an inductance value set substantially equal to or lower than an equivalent inductance value when the circuit of the rotary transformer side is viewed from the reception side circuit.

Abstract: A head protection device in a data recording circuit is disclosed in which write-current of a given level that corresponds to a high or low level of coercive force of the magnetic recording portion of a recording medium is provided as an output and supplied to a magnetic head for data recording and reproduction. The data recording circuit comprises an alternate write-current supply portion for alternately providing, by a suitable current switching means, a low write-current corresponding to a low coercivity magnetic head and a high write-current corresponding to a high coercivity magnetic head, a common output portion for providing data to be recorded using a low current or a high current from the alternate write-current supply portion. The low coercivity magnetic head and the high coercivity magnetic head can be at least electrically switched. A current protection portion for a current switching means is provided so as to prevent generation of high write-current at the alternate write-current supply portion.

Abstract: A CPU sets an SPM driver in SPM start-up mode when a SPM is started up. At this time, a voltage selector applies, to a driver circuit, a voltage (high voltage) boosted by a voltage booster. A starter control circuit controls, during the period of an SPM start-up mode, the driver circuit with the high voltage applied thereto, thereby starting up the SPM. After the SPM has been started up, the CPU sets the SPM driver in PWM mode. At this time, the voltage selector switches the voltage applied to the driver circuit, from the boosted voltage to the voltage (low voltage) of a power supply. During the period of the PWM mode, a PWM circuit controls the driver circuit with the low voltage applied thereto, so as to rotate the SPM at a rated speed.

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: A programmable write equalization circuit includes a first digital clock that is used as a reference to indicate data rate, a second digital clock used to indicate write equalization quantization, a look-up table used to store waveforms used in equalizing the input from the first digital clock domain to the second digital clock domain, a counter used to indicate the number of bits within the look-up table that are to be used for each translation, a polarity detector used to detect the current state of the input data, a non-return-to-zero (NRZ) filter used to indicate the placement of data transitions and non-transitions, and a software interface including programmable registers to control each one of the parameters within the equalization circuit.

Abstract: A system and method enable boosting a bias applied to a load so as to facilitate reversing the direction of the bias applied relative to the load. The amount of boosting provided to facilitate reversing the bias polarity, depends on a substantially fixed boost voltage, which can be programmable. Thus, by setting the boost voltage to a predetermined voltage improved performance can be achieved, including, for example, improving the rise and/or fall times of bias current applied to an inductive load.

Abstract: A disk drive is disclosed comprising a disk and a head actuated radially over the disk. A pattern detector detects a predetermined pattern in write data to be written to the disk, and in response, adjusts a write current overshoot in a write current applied to the head.

Abstract: A write driver circuit selectively provides write current through a write head in first and second opposite directions. First and second active devices are driven with first and second pre-drive signals. Third and fourth active devices are driven with third and fourth pre-drive signals. First and second pull-up resistances are provided respectively between the first and second active devices and a fixed voltage, and third and fourth pull-up resistances are provided respectively between the third and fourth active devices and the fixed voltage. A first capacitor is connected between the first active device and an intermediate point of the third pull-up resistance, and a second capacitor is connected between the second active device and an intermediate point of the fourth pull-up resistance.

Abstract: A data storage device, data write method, and program to avoid extra power consumption and suppress a write error that may result from voltage variations. To write data onto a magnetic disk, a write circuit generates a write current that is to be supplied to a write head. The write circuit operates on a positive power supply voltage provided by a host computer, and on a negative power supply voltage generated by a programmable DC-DC converter mounted on a hard disk drive's card. The magnitude of the negative power supply voltage generated by the programmable DC-DC converter is varied in accordance with the temperature surrounding the magnetic disk. Further, the magnitude of the negative power supply voltage generated by the programmable DC-DC converter is varied in accordance with the magnitude of the positive power supply voltage supplied from the host computer.

Abstract: An apparatus configured according to characteristics for driving a write head to write to a memory device includes: (a) a current directing circuit directing a write current through a first circuit path or a second including the write head in response to a first or second write signal; (b) at least one of: (1) an impedance system for including at least one impedance unit within each of the first and second current paths; and (2) a current system for including at least one circuit element between a locus at each end of said write head and a supply voltage; and (c) a control unit coupled with at least one of the impedance system and the current system for effecting the including for at least one of the impedance system and the current system to effect configuring the apparatus.

Abstract: An apparatus for use in applying write signals including a first and second write signal for a write head to write information to a memory device includes: (a) a current director for receiving the write signals and directing a write current to establish a write voltage across the write head in a first excursion in response to the first write signal and in a second excursion in response to the second write signal; the first and second excursions occurring about a common mode voltage; (b) a voltage drop unit coupled with a supply voltage and the current director at a connection locus for establishing the common mode voltage substantially equal with the supply voltage less a voltage drop; and (c) a switching unit coupled with the voltage drop unit and the connection locus and cooperating with the voltage drop unit to vary the voltage drop.