Abstract: A method in a magnetic storage disk drive for independently learning and thereafter canceling repeatable runout that is written to the servo fields of each servo track during the servo writing process. The method does not require a servo writer because the disk drive may independently detect the runout without spinning out of control in response to such runout by operating its servo control loop in a low bandwidth mode so that it is less responsive to the higher frequency components of the runout, and by removing the effect of the DC component of the runout or selected harmonics on each revolution.

Abstract: A read/write preamplifier circuit is provided that includes a fault detecting circuit that detects when two or more read/write preamplifiers are concurrently selected for communicating with their associated data heads and means for notifying the drive controller of that condition. In one embodiment of the invention, the means for notifying the drive controller that two or more preamplifiers are concurrently selected includes a data storage register that is readable by the drive controller and that has a fault flag which is set when two or more preamplifiers are concurrently selected. Also, in one embodiment, the fault detecting circuit includes a fault-detect transistor that drives a predetermined current if the preamplifier is elected. The collectors of the fault-detect transistors of each preamplifier are electronically coupled to each other and to a sensing circuit that senses if the fault-detect transistors of two or more preamplifiers are concurrently driving the predetermined current.

Abstract: A coarse magnetic template pattern is transferred to a data storage surface of a disk by magnetic printing techniques. As printed, the template pattern essentially provides clocking and may provide radial position information. The disk is then assembled into a completed and enclosed disk drive. The template pattern is then used by the disk drive to self-write highly resolved product embedded servo patterns onto storage surfaces of each data disk including the surface having the printed template pattern.

Abstract: A method of writing data to a magnetic data storage medium is provided. A peak amount of write current is provided to the transducer, after which the amount of write current is reduced to a second amount of write current, lower than the peak amount. In one embodiment, the second amount of write current is then maintained at a steady state value. In one embodiment, the magnitude of the steady state value is greater than the magnitude of the critical current. In one embodiment the magnitude and duration of the peak write current for each transducer are stored in memory and retrieved when the corresponding transducer is selected. Also provided is a disc drive adapted to implement the aforementioned methods.

Abstract: A cassette houses a first and a second tape-like recording medium. The cassette is provided with a first and a second reel, at least a first tape guide provided between the first and second reels, a third and a fourth reel and at least a second tape guide provided between the third and fourth reels. The first tape-like recording medium is wound around the first and second reels via the first tape guide. The second tape-like recording medium is wound around the third and fourth reels via the second tape guide. The first and second reels may be arranged in a first direction in the cassette. And the third and fourth reels may be arranged in a second direction orthogonal to the first direction in the cassette. The cassette may have a first side face formed in the first direction and a second side face formed in the second direction, each side face having an opening through which data is recorded on or reproduced from the first or the second tape-like recording medium by a recording and reproducing apparatus.

Abstract: A device for write precompensation of data signals to be recorded on a magnetic medium, has an input for receiving input data signals and an output for supplying the output signals to be recorded, at least a plurality of the signal transitions in these output data signals being delayed with respect to the corresponding signal transitions in the input data signal, the signal path between the input and the output including a series arrangement of a filter circuit and a hysteresis circuit, the hysteresis circuit receiving the output signal of the filter circuit and supplying a binary signal as its output signal. This write precompensation device simply enables allowance to be made for the influence of a large number of preceding symbol values on a transition to be recorded. When the device is combined with a known write compensation device it suffices to use a simple filter.

Abstract: A method for determining servo loop gain of a servo loop in a disc drive includes performing a plurality of seek operations, each seek operation moving a head in a disc drive across a plurality of tracks on the disc. Afterwards, the head is settled over a radial position on a track and a signal is injected into the servo loop at the first frequency. At least two values generated by portions of the servo loop are measured to determine a servo loop gain.

Abstract: A clamp circuit for clamping a terminal of an H-bridge circuit. The clamp circuit is capable of being applied to a voltage in excess of 5V including 8 volts.

Abstract: The present invention provides a method and apparatus for moving a head arm assembly to a landing zone in a disk drive storage device. In disk drive according to the present invention, a control means responds to termination of a read/write operation by applying a drive current for moving an actuator arm toward an actuator lock, and then continuously applies the drive current to the actuating means to maintain an engagement of the actuator arm with the actuator lock stopped at a predetermined position, after the termination of read/write operation, and then stops a rotation of said rotating data recording disk.

Abstract: A magnetic tape recording/playback apparatus, and a method of operating the apparatus, which minimises or eliminates the tape damage which is caused by the tape-driving capstan spinning and skidding across the tape at start-up. Initial acceleration of the capstan is held to a relatively low level when capstan speed is below a predetermined value and capstan acceleration is at a higher level at capstan speeds above said predetermined value. Intermediate levels of capstan acceleration can be set for intermediate speeds.

Abstract: A magnetic storage system having one or more rotating disks is disclosed. In a preferred embodiment, each rotating disk has two magnetic surfaces which each contain a number of tracks. Each track has one or more data regions and one or more embedded servo sectors. First and second transducers are respectively suspended over first and second tracks corresponding to first and second magnetic surfaces. The second transducer determines an off-track position with respect to the second track by reading from the data region of the second track. Once the off-track position is determined for the second transducer, that information is used to position the first transducer with respect to the first track and position the second transducer with respect to the second track as the first transducer writes to the first track. Furthermore, the first transducer is positioned at a correction rate that exceeds the rate at which the first transducer encounters embedded servo sectors in the first track.

Abstract: A magnetic disk device reproduces information from a magnetic disk by using a magneto-resistive head. The magnetic disk device includes a temperature detecting unit which detects an ambient temperature. A sense current control unit controls a sense current based on the ambient temperature detected by the temperature detecting unit, the sense current being supplied to the magneto-resistive head to detect a change of a resistance of the magneto-resistive head for the magnetic disk in a magnetic field.

Abstract: The present invention is a method and apparatus for providing servo information on a disk in a hard disk drive. The hard disk drive has a disk with a plurality of tracks. Each of the plurality of tracks having at least one servo sector having a first half track portion and a second half track portion. A first location of the first half track portion of the at least one servo sector is erased using a first predetermined field. A second location of the first half track portion that is adjacent to the first half track portion of the at least one servo sector is erased using a second predetermined field. Various embodiments are disclosed.

Abstract: A disk drive system having a disk used to store information is disclosed. In one embodiment, the disk includes a servo track having a servo track pitch and a data track having a data track pitch. The servo track pitch and the data track pitch are unequal to one another. A method of reading data from a disk is also disclosed. The method includes the steps of: (1) providing a plurality of servo tracks, each having a track number; (2) providing a plurality of data tracks each having a data track number, wherein the number of servo tracks within a particular region of a disk are related to the number of data tracks within the particular region by a ratio defined as a TPI scale factor; (3) obtaining instructions from a host to read from a particular data track number; and (4) determining which servo track number should be used to access the particular data track.

Abstract: Methods and apparatus for reducing overall seeking acoustics in a head-disk apparatus are disclosed. In accordance with one aspect of the present invention, a method for reducing overall seeking acoustics in a disk drive apparatus, which includes an actuator, involves calculating an error that is a measure of a difference between a desired trajectory for the actuator and an actual trajectory for the actuator, and calculating a preliminary gain. The method also includes determining when the preliminary gain exceeds a minimum acceptable gain limit, and updating a current command using the preliminary gain and the velocity error when the preliminary gain exceeds the minimum acceptable gain limit. The preliminary gain is generally arranged to enable the updated current command to reduce the overall seeking acoustics. The updated current command is sent to a power amplifier which then generates a seek current signal using the power amplifier and the updated current command.

Abstract: A voltage-biasing, voltage-sensing differential preamplifier having a high input impedance preamplifier circuit to amplify magnetic data readback signals from a magnetoresistive (MR) sensor and feedback circuits to simultaneously hold the electrical center of the MR sensor at a prescribed potential (usually ground) while applying a predetermined constant differential voltage-bias across the MR element. The feedback circuits provide a stable operating point for the MR sensor at the desired bias-voltage, and maintain the average potential on the MR sensor at or near the disk substrate potential to limit the destructive effects of MR sensor contact with conducting asperities.

Abstract: A new class of fixed partial response targets are disclosed for use in a PRML magnetic medium read channel. The preferred embodiment exhibits an equalization response characterized by the polynomial 7+4*D−4*D2−5*D3−2*D4, where D represents the unit delay operator. This read channel target provides improved matching to the inherent magnetic channel over the known canonical class of targets (1−D)(1+D){circumflex over ( )}N, and thereby reduces equalization losses. The improved spectral matching reduces amplification of noise in the channel, thereby reducing bit-error-rates. The new class of targets also exhibits a spectral null at DC, reducing problems for offset cancellation circuitry and making the disk drive less sensitive to thermal asperities. It also exhibits a spectral depression rather than a spectral null at the Nyquist frequency, making quasi-catastrophic error sequences virtually impossible.

Abstract: A disk drive with means to prevent accidental landing of a head/slider on the disk surface is described. In one embodiment a shock sensor is provided to sense external shocks received by the mechanism. During loading (positioning) of the actuator bearing the head/slider over the disk, if a shock is sensed, loading is stopped and an immediate unloading is performed to return the actuator to the withdrawn position. In another embodiment the unload operation is performed when the rotational speed of the disk is changed. In another embodiment the unload operation is performed when the rotational speed of the disk drops below a threshold. A circuit and method for detecting when the rotational speed of the disk drops below a threshold is also provided. The unloading in the various embodiments may be performed using velocity control or without velocity control.

Abstract: A method of determining the subtrack within zone P on a recording medium is provided. The recording medium has a plurality of zones 1 through Q. Each zone has a plurality of subtracks 0 through M. Each subtrack has a plurality of sectors 0 through N. Each sector has a position identifier field. Each position identifier field has a plurality of information units for recording a position identifier. The position identifier for Jth sector of subtrack I is identified as S(I,J). A preferred method comprises obtaining the local subtrack value as S(I,0), a space-efficient way to store and extract subtrack location information.

Abstract: A clock generator applicable to a sample servo type magnetic disk drive is disclosed. Reproduced signals z(t) from a clock pattern are digitized by an A/D converter (33) before being fed to a phase comparator (52). An arithmetic unit (61) calculates an inner product of N sampled values and N weighting factors in a linear combination, and a D flip-flop (62) provides a phase comparison error signal f(&thgr;). The signal f(&thgr;) is converted by a D/A converter (53) to analog format before being supplied as a control signal to a VCO (51) via a loop filter (54). A clock signal CLK from the VCO (51) is controlled in phase so as to generate a clock signal CLK synchronized with the reproduced signals z(t). When the weighting factors are arranged so that their total sum becomes zero, the signal f(&thgr;) is free from adverse effects of DC elements superposed on the reproduced signals z(t), whereby a clock signal CLK in precise synchronism with the reproduced signal z(t) is obtained.