Abstract: A phase-variable frequency multiplier includes: a 90-degree divider for dividing an input signal into an I-signal and a Q-signal; an amplitude setting circuit for distributing each of the I-signal and the Q-signal to two paths, setting amplitudes of two of four signals including the two distributed I-signals and the two distributed Q-signals depending on a phase shift amount of the input signal, and outputting as set signals, the four signals including the signals with the set amplitudes; a first mixer for multiplying one of the two I-signals included in the set signals by one of the two Q-signals included in the set signals to generate a first signal having a frequency being twice the frequency of the input signal; a second mixer for multiplying the other of the two I-signals included in the set signals by the other of the two Q-signals included in the set signals to generate a second signal with an amplitude ratio with respect to the first signal, being a tangent or a reciprocal of a tangent of the phase sh

Abstract: A data storage device is disclosed comprising a head actuated over a disk comprising servo data for defining a plurality of data tracks, wherein each data track comprises a plurality of data segments. First data is written to data segments of a first data track, and second data is written to data segments of a second data track. After writing the second data, the first data is read at multiple off-track offsets of the first data track to measure an average off-track read capability (OTRC) of the first data track. A cross-track profile is generated for a first data segment of the first data track, and at least part of the cross-track profile is correlated with the measured average OTRC.

Abstract: A data storage device is disclosed comprising a head actuated over a disk comprising servo data for defining a plurality of data tracks, wherein each data track comprises a plurality of data segments. First data is written to data segments of a first data track, and second data is written to data segments of a second data track. After writing the second data, the first data is read at multiple off-track offsets of the first data track to measure an average off-track read capability (OTRC) of the first data track. A cross-track profile is generated for a first data segment of the first data track, and at least part of the cross-track profile is correlated with the measured average OTRC.

Abstract: A data storage device is disclosed comprising a head actuated over a disk comprising servo data for defining a plurality of data tracks, wherein each data track comprises a plurality of data segments. First data is written to a first data segment of a first data track, and second data is written to a second data segment of a second data track. After writing the second data, a quality metric is measured for at least two off-track offsets of the first data segment. A track pitch is estimated between the first data segment and the second data segment based on the quality metrics, and a track trajectory is generated for the second data segment based on the estimated track pitch. Third data is written to the second data segment based on the track trajectory.

Abstract: Systems and techniques for writing data to a Shingled Magnetic Recording (SMR) magnetic data storage device. At least one processor may determine whether the distance between a first data track and a second data track is less than a threshold distance. If the distance is less than a threshold distance, the at least one processor may cause a write head to refrain from writing to the sector of the second data track. The at least one processor may cause data from the first data track to be copied to another storage location and write data to the sector of the second data track.

Abstract: In one embodiment, a magnetic data storage system includes a magnetic disk medium, a microwave-assisted magnetic recording (MAMR) head including a main pole adapted for recording data to the magnetic disk medium having a first recording width, a spin torque oscillator (STO) adapted to apply a high-frequency magnetic field to the magnetic disk medium during a recording operation, wherein the STO is operable or inoperable when in an on or off state, respectively, wherein the main pole has a second recording width when the STO is in the on state, and the second recording width is different from the first recording width, a drive mechanism for passing the magnetic disk medium over the MAMR head, a read head including a magnetoresistance sensor, and a controller adapted for adjusting a shift quantity of the magnetic head depending on whether the STO is in the on or off state.

Abstract: A method for dividing a data area on a disk into a plurality of concentric zones and determining a format for each zone so that data tracks in the zone have the same number of data sectors. The method includes dividing a data area into a plurality of zones with provisional boundaries. The method also includes determining a linear recording density for a selected zone. The method further includes selecting the number of data sectors per data track corresponding to the determined linear recording density from specified values. Moreover, the method includes resetting a boundary of the zone at a new boundary shifted from the provisional boundary according to a selected value.

Abstract: A method for dividing a data area on a disk into a plurality of concentric zones and determining a format for each zone so that data tracks in the zone have the same number of data sectors. The method includes dividing a data area into a plurality of zones with provisional boundaries. The method also includes determining a linear recording density for a selected zone. The method further includes selecting the number of data sectors per data track corresponding to the determined linear recording density from specified values. Moreover, the method includes resetting a boundary of the zone at a new boundary shifted from the provisional boundary according to a selected value.

Abstract: Embodiments in accordance with the present invention provide a magnetic disk drive capable of achieving error recovery stably in a simple configuration in the event of thermal asperity (TA) and minimizing the error recovery time required, and a method for controlling the disk drive. According to one embodiment, if TA occurs, a cutoff frequency of a high-pass filter to which a data read signal is input is first increased and a loop gain of a low-order finite impulse response (FIR) filter connected in series to an FIR filter is also increased as high as possible. Next, a Viterbi decoder to which a signal is input from the low-order FIR filter provides feedback to the low-order FIR filter so that an input signal error becomes a minimum. Tap coefficients of the low-order FIR filter are thus optimized.

Abstract: Provided is a dental restoration having improved conformity and bonding to a foundation. A method for producing such a dental restoration and a porcelain paste for the dental restoration are also provided. The dental restoration includes a ceramic framework and a porcelain layer deposited at least on the inner surface of the ceramic framework for being bonded by a dental adhesive to the outer surface of an abutment tooth in the mouth. In one preferred embodiment, the ceramic framework is formed of a zirconium oxide ceramic. In another preferred embodiment, the inner surface of the porcelain layer is silane-coupling-treated.

Abstract: Embodiments of the invention prevent offtrack write that will be caused due to a head vibration in a storage device. In one embodiment, a hard disk drive (HDD) judges approval/disapproval of write of user data to a magnetic disk by using a read signal for user data in addition to servo data in write processing. Thus, a head vibration which cannot be precisely detected based on servo data is detected to prevent off-track write. More specifically, the HDD acquires a read back signal amplitude of a read element with respect to a user data sector within adjacent servo data during a write access phase, and detects a vibration from a maximum value MAX and a minimum value MIN of the read back signal amplitude to judge data write approval/disapproval.

Abstract: Embodiments in accordance with the present invention provide a magnetic disk drive capable of achieving error recovery stably in a simple configuration in the event of thermal asperity (TA) and minimizing the error recovery time required, and a method for controlling the disk drive. According to one embodiment, if TA occurs, a cutoff frequency of a high-pass filter to which a data read signal is input is first increased and a loop gain of a low-order finite impulse response (FIR) filter connected in series to an FIR filter is also increased as high as possible. Next, a Viterbi decoder to which a signal is input from the low-order FIR filter provides feedback to the low-order FIR filter so that an input signal error becomes a minimum. Tap coefficients of the low-order FIR filter are thus optimized.

Abstract: Embodiments of the invention prevent offtrack write that will be caused due to a head vibration in a storage device. In one embodiment, a hard disk drive (HDD) judges approval/disapproval of write of user data to a magnetic disk by using a read signal for user data in addition to servo data in write processing. Thus, a head vibration which cannot be precisely detected based on servo data is detected to prevent off-track write. More specifically, the HDD acquires a read back signal amplitude of a read element with respect to a user data sector within adjacent servo data during a write access phase, and detects a vibration from a maximum value MAX and a minimum value MIN of the read back signal amplitude to judge data write approval/disapproval.

Abstract: Embodiments of the invention provide a magnetic disk drive that does not generate errors when information is read even if considerable time has elapsed after the information was written on the magnetic disk. In one embodiment, a magnetic disk has a storage area divided into a plurality of sectors ST1. Time stamps TP1 corresponding to each sector data m1 stored in the sectors ST1 are stored in a time stamp recording medium. A processor controls the magnetic disk drive to read time stamps TP2 of sector data m2 stored in any sectors ST2 of the sectors ST1 and refresh sector data m3 selected based on an elapsed time calculated from information about the time when the time stamps are read and the time stamps TP2.

Abstract: The read/write offset between the read head and write head is used to determine the head width ratio between the read head width and write head width. The servo information is written onto the magnetic disk in accordance with the APC value and track pitch that are derived from the determined head with ratio.

Abstract: Disclosed is a data storage device to provide servo patterns of a track pitch individually consistent with head characteristics (writing width, and reading width) in a recording medium of a hard disk device. The data storage device is provided with a disk having pitch information indicating a track pitch recorded in a predetermined area, and a head for scanning the disk to read the TPI ID and reading/writing data from/in the disk by being subjected to seeking control based on the TPI ID. The TPI ID is recorded as a part of a servo pattern in a TPI ID embedded area provided in an outer periphery of a data area of the disk.

Abstract: Embodiments of the invention provide a magnetic disk drive that does not generate errors when information is read even if considerable time has elapsed after the information was written on the magnetic disk. In one embodiment, a magnetic disk has a storage area divided into a plurality of sectors ST1. Time stamps TP1 corresponding to each sector data m1 stored in the sectors ST1 are stored in a time stamp recording medium. A processor controls the magnetic disk drive to read time stamps TP2 of sector data m2 stored in any sectors ST2 of the sectors ST1 and refresh sector data m3 selected based on an elapsed time calculated from information about the time when the time stamps are read and the time stamps TP2.

Abstract: The read/write offset between the read head and write head is used to determine the head width ratio between the read head width and write head width. The servo information is written onto the magnetic disk in accordance with the APC value and track pitch that are derived from the determined head with ratio.

Abstract: A method for controlling write current to a write head during data write on a hard disk drive is disclosed. A direct access storage device includes a rotating storage medium in which data are magnetically written, a write head for writing data in the rotating storage medium, and a write current control circuit for changing write current-value settings to be supplied to the write head according to a predetermined elapsed time from the beginning of a write operation.

Abstract: Disclosed is a data storage device to provide servo patterns of a track pitch individually consistent with head characteristics (writing width, and reading width) in a recording medium of a hard disk device. The data storage device is provided with a disk having pitch information indicating a track pitch recorded in a predetermined area, and a head for scanning the disk to read the TPI ID and reading/writing data from/in the disk by being subjected to seeking control based on the TPI ID. The TPI ID is recorded as a part of a servo pattern in a TPI ID embedded area provided in an outer periphery of a data area of the disk.