Abstract: An apparatus and method for writing servo data to a rotatable disc of a disc drive, the servo data used to control the position of a read/write head adjacent the disc. An internally mounted clock head assembly provides disc angular position information by writing and subsequently reading a clock pattern to and from the disc. A radial position detection assembly identifies the radial position of the head. A control circuit controls the function and position of the head to write the servo data to the disc in response to the disc angular and head radial position information. The clock head assembly and radial position detection assembly remain contained within the disc drive during subsequent field use, and can be configured to detect the application of rotational vibration to the disc drive and to rewrite the servo data.

Abstract: In a high-speed tape winding operation of a magnetic recording and reproducing apparatus, stable tape-stopping operation without generating any damages of the tape. In addition to the mechanical braking means, a reverse braking force is applied to a drive motor for rotating reels depending on the tape conditions so as to diminish the rotation inertia of the drive motor and dispense with a strict operation timing and precision of the mechanical braking means.

Abstract: A disc drive includes a head with an air bearing surface that provides a fly height spacing. A fly height spacing control system provides a control signal to a head electrical connection on a head and a disco electrical connection on a disc. Fly height is controlled electrostatically. A disconnect circuit couples the control signal to the disc electrical connection. The disconnect circuit provides a disconnection of the control signal when contact is sensed. A contact sensor senses an electrical current component of the control signal that indicates contact between the head and the disc.

Abstract: A method and apparatus are provided for closed loop control of head load velocity in rotating media mass storage applications. A novel pulsed current velocity controlled head load/unload circuit is provided that uses the back EMF analog signal to modulate pulse amplitude. A system is thus provided having amplitude modulation of a fixed period current pulse train via back EMF feedback, whereby there is no need to monitor back EMF via A/D conversion circuitry.

Abstract: An apparatus and method for adjusting balance in a disk drive, and a method for assembling a disk drive, enables the modification of dynamic balance reliably and efficiently. The apparatus adjusts balance in a hard disk drive having disks and a spindle which are assembled in a base. The acceleration to be applied from an actuator is made to act on the top end of the spindle through a holder plate in one accelerator, while the acceleration to be applied from an actuator is made to act on the base end of the spindle through the base in another accelerator.

Abstract: Linearizing hysteresis of a microactuator for a disc drive by modeling the microactuator with a first polynomial equation to provide a linear displacement response of the microactuator responding to an applied voltage, deriving a set of constants from a plurality of burst patterns for use with the first polynomial equation to provide a set of variables for use in resolving the second polynomial equation to provide a set of equations from which a set of constants can be derived for use by the second polynomial equation to provide a voltage to the microactuator to displace the microactuator by a predetermined incremental distance.

Abstract: A method and apparatus for detecting and recovering from head instability in a magneto-resistive (MR) transducer head of a disc-drive system. A head-instability-recovery circuit is described for use in disc drive to recover from a head-instability condition of an MR transducer head. This circuit includes a controller and a current source that supplies current to the MR head. The current source is controlled to supply a nominal amount of current to the MR head when operating in a normal mode, and to supply one or more current bursts having a current above the nominal supply current in order to recover from the head-instability condition. Also described is a method for recovering from a transducer-instability condition of an MR transducer of a disc drive, including detecting a situation that indicates a head-instability-recovery operation is desired, and performing the head-instability-recovery operation.

Abstract: A method of handling multiple resonance frequencies in a disc drive includes monitoring a position error signal (PES) for an actuator arm, generating a plurality of feedforward compensation signals from the PES using a plurality of bandpass filters, and applying the compensation signals to a servo control signal. Each filter has a center frequency that is set to a problematic resonance frequency. The method may also include identifying the problematic frequencies by, for example, commanding a movement of the actuator arm, collecting data points for the PES that are associated with the movement, and performing a digital fourier transform of the data points to identify resonant frequencies. Other methods of identifying problematic frequencies include analyzing PES zero-crossing data, or using principal component analysis.

Abstract: A magnetic disk unit has two actuators each rotating on a common rotary shaft. The two actuators are driven by a voice coil motor. The voice coil motor comprises: a magnetic circuit comprising a magnet provided for the two actuators on a common basis and two yokes, which are associated with the two actuators, respectively, said two yokes being disposed at both sides between which the magnet intervenes; and two coils provided for the two actuators, respectively.

Abstract: A disk drive is disclosed which calibrates at least one zone parameter in the field. During an off-line state of the disk drive, at least one of the adapted zone parameters is calibrated. During an active state of the disk drive, a read error is detected and a data-recovery firmware procedure is executed using adapted zone parameters in an attempt to recover data associated with the read error. If the data is successfully recovered from the data sector using the data-recovery firmware procedure, an adapted zone parameter counter is incremented and the operating zone parameters are updated with the adapted zone parameters if the adapted zone parameter counter exceeds a predetermined threshold.

Abstract: A magnetic tape drive has a brake mechanism section which can transfer the state of a reel table from a non-brake state to a brake state by using an electric power that remains after a start of a power failure of a commercial power source. The drive further has a first power failure detecting section which, when a power failure of the commercial power source is detected, transmits a first power failure detection signal; and a controlling section which, when the first power failure detection signal is transmitted in a fast-forwarding state or a rewinding state, transfers the non-brake state of the brake mechanism section to the brake state.

Abstract: A method and apparatus are provided for identifying spindle imbalance in a hard disk drive. Position error signal (PES) samples are received from a plurality of sectors of a predefined cylinder for a plurality of disk surfaces. The PES samples are measured and stored for a defined number of revolutions for each of the plurality of disk surfaces. For each of the plurality of disk surfaces, a repeatable runout (RRO) of the PES is computed for the defined number of revolutions. A first harmonic discrete Fourier transform (DFT) and a first harmonic phase of the RRO are computed. Then a mean repeatable runout (MRRO) is computed. A first harmonic DFT and a first harmonic overall phase of the MRRO are computed. For each of the plurality of disk surfaces, cross-correlation coefficients are computed and summed to identify a spindle imbalance factor. The identified spindle imbalance factor is compared with a predefined threshold value to identify spindle imbalance in the hard disk drive.

Abstract: A disk drive that includes a base, a magnetic disk, a rotary actuator that carries a head for reading and writing data from the disk in a track-following mode under the control of a servo control system, and at least two sensors—one fixed sensor rigidly coupled to the overall disk drive and one mobile sensor mounted to the rotating actuator—for differentially detecting accelerations of the rotary actuator relative to the overall disk drive and its disk. The disk drive detects and actively compensates for accelerations imparted to a balanced actuator that has an effective imbalance. The fixed sensor is preferably mounted to a PCBA that is secured to the base. The mobile sensor is preferably mounted to an actuator arm of the rotary actuator, as far outboard as possible, and so as to align with the fixed sensor as the rotary actuator swings through its range of travel. The preferred sensors are linear accelerometers.

Abstract: A medium transfer mechanism of a recording medium storage apparatus is provided, which is capable of reducing a load on a motor or a gear, when a recording medium is transferred. In order to store a recording medium T in libraries L1 and L2, the medium transfer mechanism of a recording medium storage apparatus includes a driving side engaging element which is moved by a motor. A follower side engaging element engages with the driving side engaging element. A predetermined gap is between the driving side engaging element and the follower side engaging element. A biasing device biases the follower side engaging element for engaging with the driving side engaging element.

Abstract: An information handling system, such as a disc drive, includes a base, a disc stack rotatably attached to the base, and an actuator assembly movably attached to the base. A region of the disc stack is identified as a parking band, and when power is not provided to the disc drive, the actuator assembly is held in a parked position within the parking band by a magnetic latch. The magnetic latch is overcome during a powerup process by a voice coil motor coupled to the actuator. Other regions of the disc stack are associated with various functions performed by the voice coil motor as the actuator passes over such regions.

Abstract: A servo system and method for calibrating servo index positions of a magnetic tape for track following linear servo edges, each servo edge comprising an interface between dissimilar recorded servo signals, the edges on opposite lateral sides of a middle servo signal. A servo loop laterally positions a servo sensor where the servo signals are at estimated ratios representing the locations of the servo edges. An independent position sensor indicates the mechanical lateral position of the servo sensor at the sensed servo edges. The servo loop repositions the servo sensor to a plurality of lateral positions at predetermined displacements from the independent position sensor sensed servo edges, and track follows at each of the predetermined offsets.

Abstract: To optimize the life of a magnetic disk data storage device it is recognized that the accessing of data on the disk data surface should mimic the varying effective lubricant protection over the disk surface. The lubricant applied to the disk data surfaces migrates outward during drive operation. To match the disk surface protection to the frequency of data accesses at the storage locations, the stored data files are periodically examined to determine how recently access has occurred and the number of accesses during a most recent fixed period to determine whether the data file is to be stored in radially inner or radially outer portions of the band of concentric data tracks. By thus allocating the data file storage location, the data is accessed and intermittent contact between disk surface and transducer carrying slider occurs with greatest frequency where the lubricant coating is least depleted and most robust.

Abstract: An information handling system, such as a disc drive, includes a base, a disc stack rotatably attached to the base, and an actuator assembly movably attached to the base, with multiple movable mill-actuator arms mounted on one portion of the actuator assembly. Attached to an end of the actuator is a voice coil which forms a portion of a voice coil motor. Magnets attached to the base form the other portion of the voice coil motor. A current driver for the voice coil delivers an amount of current to the voice coil to move the actuator assembly. Attached to another end of the actuator assembly is one or more transducers. In order to minimize the disturbance of a seeking milli-actuator, the operation to be executed is to cause the first milli-actuator to return slowly to its rest or zero position. A rate of return control circuit is implemented to drive a milli-actuator such that a milli-actuator at a non-zero or non-rest position will be returned to a rest position at a rate slower than a seeking milli-actuator.

Abstract: A controller generates a control signal that is input into a voice coil motor and causes an actuator to move to a particular position on a storage disk. An actuator model of the actuator is also coupled to the output, of the controller. The actuator model is used to estimate the response of the actuator when a signal is input into the voice coil motor. If some voltage is induced in the voice coil motor by an external vibration or resonance of the actuator, then the voltage output by the actuator will not be equal to the estimated voltage output by the actuator model. The difference of the estimated voltage and the actual voltage output the actuator is input into a resonance controller. The resonance controller then generates a compensation signal that is combined with the control signal to compensate for any actuator resonances.

Abstract: A data tape drive senses the ambient temperature and the relative humidity of the environment in which the tape drive is operating. The tension exerted on the data tape by the tape drive is then adjusted as a function of the temperature and/or humidity. When the tape is more rigid at low temperature/humidity, the tension is increased. At nominal temperature/humidity, a nominal tape tension is used. However, under elevated conditions a lower tension is utilized to avoid damaging the tape. The sensors also may be used to completely prohibit drive and tape operation when the tape drive is in an extreme environment that is beyond an acceptable design range. Tape acceleration profiles due to atmospheric conditions are changed based on the propensity of the tape to stick to the head.