Abstract: The optimum head-field intensity for saturation recording is assumed to be 560×103 A/m or more. Under a condition where the recording track width of an information recording medium is equal to or less than 60 nm, the optimum head-field intensity Y satisfies the following inequalities (1) and (2): Y?(X2?119×X+4135)×1000??(1) Y?(X2?119×X+const)×1000??(2) where X denotes the nondimensional value of the recording track width divided by 10?9 m, and Y denotes a magnetic field (expressed in units of A/m) which a magnetic pole for head-field application applies to the center of the information recording medium in the direction of the thickness thereof. Note that const=?0.8×v2+33.7×v+4250 if the relative velocity v between the head and the medium at the position of the head is less than 20 m/sec, or const=4600 if the velocity v is equal to or more than 20 m/sec.

Abstract: A phase-acquisition (PA) loop for a read channel comprises an accumulator, a comparator, and a filter. The accumulator holds an acquired phase-correction value corresponding to a difference between a phase of a sample clock and a phase of data carried by a read signal, and provides the acquired phase-correction value to a circuit that modifies the read signal to compensate for the phase difference. The comparator receives a reference phase-correction value that also corresponds to the difference between the phases of the sample clock and the data, and generates an error signal that is related to a difference between the reference and acquired phase-correction values. And the filter causes the acquired phase-correction value to have a predetermined relationship to the reference phase-correction value.

Abstract: On a magnetic recording medium, M sets of burst patterns are formed along a direction of rotation of a substrate in each burst pattern region. Each burst pattern is formed so as to include two types of burst signal units that have an equal length along a radial direction of the substrate. In a predetermined range, (2M) centers in the radial direction of the burst patterns are present at intervals of (1/N) times the track pitch in the radial direction. The predetermined range has a length along the radial direction of (2M/N) times the track pitch. M or N is a natural number of 2 or higher. The two types of burst signal units are formed of non-recording regions and end regions of the burst signal units overlap in the radial direction in at least one part region of the substrate.

Abstract: A storage channel, e.g., for a disk drive system, may asynchronously sample and buffer an entire sector, and then process the buffered sector to recover timing information. The storage channel may operate in an open-loop and utilize an exhaustive search to determine timing parameters. Alternatively, the storage channel may operative in a closed-loop, processing the sector once, and feeding back information obtained during decoding to the timing loop.

Abstract: Methods and recording systems are configured for recording different data simultaneously at two different depths of a tilted magnetic medium, the tilted magnetic medium having a hard axis of magnetization, the axis being out of a plane of the medium and at an angle of ?10 to ?80 degrees with respect to a direction along which data are recorded, the medium being capable of having two depths of recording. A method embodies writing with selected magnetic fields whose amplitudes and whose angles with respect to the medium hard axis direction differ at the two depths of the medium such that the recorded direction of magnetization at the respective two depths can be set independently.

Abstract: A gain controller for a gain loop of a read channel includes a comparator circuit, an accumulator circuit, and a function circuit. The comparator circuit determines an error between an actual sample of a read signal and a corresponding ideal sample of the read signal, and the accumulator circuit holds a gain-correction value and adjusts the gain-correction value in response to the error. The function circuit generates a gain-correction signal by performing a predetermined mathematical operation involving the gain-correction value, and provides the gain-correction signal to a variable-gain amplifier that is operable to amplify actual samples of the read signal. Because such a gain controller allows one to locate the variable-gain amplifier (VGA) after the analog-to-digital converter (ADC) in a read channel, the gain controller may significantly reduce the latency of the gain-acquisition (GA) loop or the gain-tracking (GT) loop of the read channel.

Abstract: Embodiments of the invention include: a hard disk drive using a read track to position for writing to a write track and generating a position error signal (PES) based upon all four servo offset bursts used to disable writing when the PES exceeds a position error threshold; a preamplifier generating the PES from four bursts from a slider reading the read track to position when the write track is to be written, and methods of writing the write track using PES from four bursts of the read track that disables writing when the PES is above the position error threshold.

Abstract: An apparatus for writing a magnetic layer writable with either low or high coercive field strength includes a magnetic head having a magnet coil and a voltage source. The apparatus includes switches between the voltage source and opposing ends of the magnet coil. Two further switches serve to maintain the direction of current flow through the magnet coil. A current measuring device determines the current intensity through the magnet coil. The current measuring device drives the switches in such a way that the current intensity in the magnet coil does not exceed or undershoot a level required for writing the magnetic layer.

Abstract: A current mirror circuit providing a fast turn on time. A node within the circuit is held at a first voltage when the current mirror is off to permit the node voltage to quickly reach a necessary value when the current mirror circuit is turned on.

Abstract: In a magnetic recording apparatus, a magnetic recording medium has a RAM area on which rewritable information can be recorded. The magnetic recording medium also has a ROM area having a pattern area in which first-type segment sequence of magnetically rewritable magnetic segments and magnetically non-rewritable nonmagnetic segments is fixedly recorded as first-type modulation information. Predetermined segments in the first-type segment sequence are magnetized and changed to magnetized segments. A segment sequence of first and second segments magnetized in one and opposite directions is used to magnetically record second-type modulation information in the pattern area.

Abstract: A method and apparatus for providing an early warning of thermal decay in magnetic storage media are provided. In accordance with an embodiment of the present invention, a test pattern that is particularly susceptible to thermal decay is written to a disk. The test pattern is then read, and the amplitude of the signal produced by the test pattern is stored. When testing for thermal decay is desired, the test pattern is again read, and the amplitude of the signal produced in the channel is compared to the stored amplitude. If the later amplitude is less than the stored amplitude by at least a predetermined amount, a thermal decay warning signal is generated. In accordance with another embodiment of the present invention, a test pattern is written to a portion of a disk that has been identified as being particularly susceptible to thermal decay. The amplitude produced by the test pattern is then stored so that it can later be compared to an observed amplitude when testing for thermal decay.

Abstract: An apparatus and associated method are described for use in a disk drive including a disk that that is supported for controlled rotation and for cooperating with a transducer arrangement for accessing the disk in performing a data operation. The disk includes an arrangement of servo track wedge segments for storing servo data such that a set of servo data is periodically available as the disk is rotated in relation to the transducer arrangement and the servo track wedges are separated by an arrangement of user data wedge segments for use in storing user data. Generally, a controller IC and a channel IC are provided. The servo data is transferred from the channel IC to the controller IC using one data protocol and user data is bidirectionally transferred between the channel IC and the controller IC using a different data protocol.

Abstract: An apparatus and method are disclosed for decoding servo data recorded on a magnetic disk drive and detecting pinned layer reversals and signal errors, for example, errors due to noise. The servo data is encoded using wide-bi-phase encoding. This encoding is detected by a magneto-resistive sensor that senses the magnetization in domains passing by the sensor. The decoder includes an A/D converter for sampling the signals emitted by the sensor, to provide a sequence of the encoded data. A trellis, such as a Viterbi trellis, is employed to decode the samples generated by the converter. The trellis includes nodes representing states, connected by paths representing transitions, among the nodes. A quality value is generated for the transitions, the quality value representing the distance between each sample in the sequence output by the A/D converter and a corresponding expected sample.

Abstract: Embodiments in accordance with the present invention relate to identifying an address of user data to be registered as a defective user data address in disk defect inspection. In an embodiment of the present invention, in the state where a write element is positioned to a target position to execute data write processing to execute normal data read processing, a write element executes data write processing. If a predefined error occurs during the data write processing, an address of user data for which the normal data write processing is executed is estimated using the error-causing servo data as a target. In addition, an address of the servo data used as the target during the normal data write processing for the estimated address of the user data is identified. If the identified address of the servo data and the address of the error-causing servo data match with each other, the estimated address of the user data is registered as a defective user data address.

Abstract: A phase error reduction system includes a control module, a phase-locked loop (PLL) module, and a harmonic removal module. The control module generates source timestamps for a plurality of synchronization marks in a source signal using a clock and generates a plurality of target tirnestamps. The PLL module determines phase errors between the source timestamps and the target timestamps and minimizes the phase errors. The harmonic removal module removes harmonics of the phase errors using a weighted moving average filter (MAF). The harmonic removal module comprises a repetitive feed forward (RFF) module that includes an amplifier the scales the phase errors, a delay buffer that generates RFF commands to reduce the phase errors, and a summing module. The MAF filters the RFF commands. The summing module provides sums of the phase errors scaled by the amplifier and the RFF commands filtered by the weighted MAF to the delay buffer.

Abstract: A method of determining a size of an error generated in a servo sector, a write control method of controlling whether to write data to data sectors successive to a servo sector according to the size of the error generated in the servo sector therein, a HDD using the write control method, and a recording media storing computer programs for executing the methods. A method of determining a size of an error generated in a servo sector of a HDD includes: reading servo information from the servo sector in which the error was generated; and determining the size of the error by the number of corresponding bits that differ from each other between the read servo information and a normal servo information.

Abstract: A phase locking apparatus is disclosed which, includes a phase error information detecting device to detect phase error information indicating the phase error. The device has a phase position determining device to determine, based on run length limited information, whether or not phase positions of a first and second value from among sampling values constituting synchronous data are under a reverse phase condition in effect when only one of the first and the second values is in excess of a predetermined threshold, and a phase error information calculating device to calculate the phase error information in each of two cases determined, one with the reverse phase condition found to be in effect and the other without effect.

Abstract: A holder unit for use in a transfer apparatus that causes a surface of a transfer master and a surface of a slave medium to be in direct contact with each other and transfers information on the transfer master surface to the slave medium surface. The holder unit includes a pair of gripping members, movable toward and away from each other, for holding the transfer master. The transfer master is stuck firmly on either or both of the pair of gripping members through or without an elastic member.

Abstract: Embodiments of the present invention help to increase the capacity and the reliability of a disk drive device to improve the manufacturing yield thereof. An embodiment of the present invention sets a data track pitch for each head slider (recording surface) in accordance with head characteristics. This method for specifying the data track pitch is based on the distance between erase band ends (EBEs) of the both adjacent data tracks. The erase band of a data track is a band defined as the area where the already written data are erased in writing the data track. The distance between the erase band ends of the both adjacent data tracks corresponds to the width SW of the area which is not erased by the adjacent data tracks. Specifying the data track pitch based on this leads to increase in the data capacity of each recording surface and secure prevention of occurrence of a squeeze error.

Abstract: An apparatus and method for controlling the common mode voltage across a data storage device write head. The write current is supplied by a first plurality of parallel current sources each independently activated to limit the common mode voltage generated across the write head. A plurality of parallel resistive elements responsive to current supplied by a second plurality of parallel current sources bias an output transistor that further controls the write current. Each of the plurality of parallel resistive elements and each of the second plurality of parallel current sources is also independently activated to limiting the common mode voltage generated across the write head.