Abstract: A head positioning system accurately positions a read/write head along a selected track of a rotating magnetic disk. In one aspect, servo information is embedded along the track with the centerline of the servo information offset a radial distance from the centerline of data stored or written along the track. The head positioning system micro-jogs the read/write head a first and a second radial distance from the centerline of servo information for a read operation and a write operation.

Abstract: A storage device is described for reading data from a hard disk drive wherein delays due to rotational latency are substantially reduced. The storage device includes a platter having a substantially planar annular surface with a geometrical center. On the platter are a plurality of generally arcuate concentric tracks. Each of the tracks is divided into a plurality of sectors that are radially outwardly disposed from the geometrical center of the platter and are bounded by radii extending from the geometrical center. Original data is written on at least one of the sectors. Further, a copy of the original data is maintained at a fixed azimuth angle from the original data during rotation of the platter about the center.

Abstract: Embedded servo sectors within a data track of a hard disk drive including a rotating data storage disk and a closed loop rotary actuator structure for positioning a data transducer head relative to the data track are written by a method including the steps of positioning the rotary actuator structure relative to the data track with a laser-interferometer-based servo writer and writing a pattern of circumferentially sequential, radially offset fine position bursts within each servo sector with the data transducer head, this step including writing-in undetermined position errors within each pattern being written, moving the disk drive to a self scan environment away from the servo writer, operating the rotary actuator structure in closed loop for following the data track by reference to the servo burst pattern, extracting the undetermined position error from each pattern thereby to iteratively determine written-in position errors, generating burst correction values from the determined written-in position errors

Abstract: An angular division apparatus for circumferentially dividing a rotating object into a plurality of areas by using Doppler pulses includes an optical head for applying a beam emitted from a light source unit to a rotating object and detecting Doppler pulses based on a shift of the frequency of the light scattered from the rotating object, and a counting unit for counting the Doppler pulses output from the optical head to determine the number of pulses for one revolution of the rotating object. The number of Doppler pulses for one revolution is divided by a division number for dividing the rotating object into a plurality of areas in the angular direction. The rotating object is divided into a plurality of areas in the angular direction thereof by using the number of Doppler pulses per divided area.

Abstract: An apparatus and associated method are disclosed for recovering user data from a data block in a disc drive in which user data are stored by way of a plurality of blocks on tracks of a disc, the blocks including data blocks in which the user data are stored in predefined increments. A head generates readback signals from the blocks and a read channel reconstructs the user data from the readback signals. An automatic gain control stage establishes a gain used to amplify the readback signal to a level suitable for use by the read channel. When an uncorrected read error is detected, the disc drive proceeds to read a previous block sequentially preceding the affected data block and sets the gain to a fixed value based upon the readback signals determined from the previous block. The fixed value of gain is then used to recover the user data from the affected data block.

Abstract: A recorder is disclosed, in which recording is effected while retrieving non-recorded blocks of a disk-like recording medium, and which is provided with means for such control that when no non-recorded block is detected in a predetermined direction as a result of check performed in response to an instruction of changing block, with which to effect recording, in the afore-said predetermined direction, previously accessed non-recorded blocks are accessed again

Abstract: A method and apparatus for writing binary servo data into the servo bursts contained on the storage medium of a storage device. The binary servo information may include track identifying information such as a track number, cylinder number, head number, sector number, index and/or SID. A burst includes T time slots, each slot comprising one cycle of the servo burst frequency, and the servo data to be written comprises X bits of binary data. Each one-bit of the servo data is represented as a slot containing a transition, and each zero-bit is represented as an empty or null slot. In this manner, the present invention provides a highly bit-efficient scheme for representing digital servo data. A high quality PES signal is assured by writing the binary servo information in such a manner as to guarantee a threshold number of transitions per burst as required for accurate peak-hold detection.

Abstract: In a magnetic disk apparatus performing a positioning operation in a sector servo system, an AGC amplification gain measuring circuit measures an amplification gain of an AGC amplifier on the basis of the reproduction of a magnetic pattern in an AGC region within a servo area of a magnetic disk. An AGC amplification gain judgment circuit judges whether the value of the amplification gain measured by the AGC amplification gain measuring circuit is out of a set range, and outputs the judgment result. When receiving from the AGC amplification gain judgment circuit a judgment result indicating that the value of the amplification gain is out of the set range, a recording/reproducing operation control circuit stops the recording operation of a recording circuit.

Abstract: An acceleration sensing device senses the acceleration of a computer such that the computer is subject to zero support force (i.e., is in a free fall), and a control microprocessor of the disk drive unit determines that such state lasts for longer than a certain minimum of time. Upon these conditions being met, the control microprocessor signals the removal of the heads from the disk to park the heads.

Abstract: A method and a circuit for correcting asymmetry in a response signal generated by a magneto-resistive head. The magneto-resistive head generates a response signal to transmit digital information read from a magnetic media storage device. The asymmetry is corrected in a negative feedback manner by squaring an output signal, modulating the squared output signal, and subtracting the modulated squared output signal from the response signal to generate the output signal. The circuit employs a differential amplifier as an input stage and a Gilbert multiplier circuit to square the output signal.

Abstract: A method of positioning a head in a disk drive is disclosed. The method includes reading a first group of servo bursts and detecting a first error value based upon the head position, reading a second group of servo bursts and detecting a second error value based upon the head position, and comparing the absolute values of the first and second error values to position the head. Preferably, the first group of servo bursts is associated with a Norms curve, the second group of servo bursts is associated with a Quads curve, the Norms curve is used for positioning the head if the absolute value of the first error value is less than the absolute value of the second error value, and the Quads curve is used for positioning the head if the absolute value of the second error value is less than the absolute value of the first error value.

Abstract: The present invention prevents catastrophic failures of a write precompensation circuit from occurring without limiting the precompensation range to a small value and also extends the range of precompensation beyond limits imposed by the duty cycle of the clock signal. The present invention prevents catastrophic failure of the write precompensation circuit by ORing either the input or the output of the comparator and the opposite phase of the clock. The 180 degree delayed clock forces any transitions that would otherwise have been missed. The present invention extends the range of a write precompensation circuit by ORing the clock and the dock delayed by a time td. The extended duty cycle that results is used to generate a longer precompensation delay. A technique is also provided to maintain constant duty cycle over a broad range of data rates.

Abstract: A plurality of digital signals having total data rates of n bit/s or less are input to a digital recording device recording digital signals having a data rate of n bit/s. The digital signals are subjected to format-conversion for the digital recording device to be recorded therein. Furthermore, signals having a data rate of n/i.sub.1 bit/s or less are subjected to format-conversion to be recorded i.sub.1 times in the digital recording device. In the case where the data rate of the digital signals to be input is n/j bit/s, the digital signals are subjected to format-conversion so that the amount of data capable of being recorded per unit time is decreased by i/j; thus, the digital signals are recorded for a long period of time under the condition that the data recording time is prolonged j times.

Abstract: A method of writing servo patterns to a floppy disk with use of a magnetic head having a head gap wider than the track pitch of the floppy disk, which method comprises writing a servo pattern to one track, thereafter moving the magnetic head by a predetermined distance in the width direction of the track to write a servo pattern, then at the time of writing servo patterns successively for a plurality of tracks in the same way as above, selecting appropriately a supply timing of write data and that of erase data to be fed to the magnetic head, and erasing in the next writing of a servo pattern a write portion of a servo pattern which deviated from the track width in the previous writing thereof.

Abstract: A method and system for developing continuous position control signals for continuously repositioning a data head relative to an addressed data track on a rotating magnetic disk. The method includes the steps of formatting the disk with a unique servo pattern to provide servo signals having servo frequencies F1 and F2, which correspond to spectral nulls in the frequency spectrum of the encoded data stored on the disks. The method further establishes addressable data track locations related to the servo pattern which have a nominal width corresponding to the width of one servo band of the pattern. After positioning the data head to a data track the method involves "side" reading with the data head the servo pattern that is adjacent both sides of the data track to develop the positional control signals as data encoded with spectral nulls at F1 and F2 is transferred to and from the disk.

Abstract: A tracking control device and method reduce the rate of occurrence of data error and improve the quality of reproduced images in a digital VTR. The tracking control device comprises a reproducing head for reproducing digital information from a recording medium, a forming circuit for forming a plurality of tracking error signals which respectively indicate positional deviations of the reproducing head from a plurality of areas into which each track formed on the recording medium is divided, a selecting circuit for selecting one tracking error signal from among the plurality of tracking error signals in accordance with their respective values, and a tracking control circuit for controlling a relative position between the reproducing head and the recording medium on the basis of the one tracking error signal selected by the selecting circuit.

Abstract: A read channel (18) for use in a mass storage system is provided. The read channel (18) includes a plurality of circuit modules circuit and an error estimation circuit (50). The plurality of circuit modules may include circuitry such as a VGA (40), an LPF (42), and an equalizer (48), for conditioning an analog data signal. The plurality of circuit modules receive the analog data signal from a disk/head assembly (12) and condition the signal to generate a digital data signal. The error estimation circuit (50) receives an analog signal from one of the plurality of circuit modules, such as the equalizer (48), and analyzes the analog signal to generate an analog error output signal (94) that is used in the read channel (18) and provided to external circuitry.

Abstract: An automatic servo address mark detecting and servo timing compensating circuit of a disk drive includes a servo address mark detection window generating unit for generating a servo address mark detection missing signal and count control signal where the servo address mark is not detected within a range of a servo address mark window of a predetermined servo sector; a servo address mark missing signal counter, which is reset according to a servo address mark detection signal, for generating a servo address mark search signal and pseudo servo address mark where a servo address mark detection missing signal count matches data loaded from the control unit; a servo address mark search controller for selecting the servo address mark search signal and pseudo servo address mark among multiple signals input by the servo address mark missing signal counter according to a select signal input by the control unit; and a servo timing compensation unit for counting system clocks, starting from the data loaded from the cont

Abstract: A tracking error signal is detected using an error detector, from cross-talk components at a point in each of the regions of several duplication areas from which reproduction is possible, and tracking control is performed using a servo circuit, based on the average value of the error signals or the average of the maximum and minimum of the peak values of the error signals from the respective areas during one scan. Even when a large amount of fast playback data is recorded, and track non-linearity is present, the fast playback can be reproduced without fail, and signals in fast playback data regions at a plurality of locations can be obtained without fail.

Abstract: A multipath channel apparatus for a data storage device wherein data is stored on a storage medium and is read from the storage medium by a transducer or for a data communications system wherein data is transmitted to a receiver. A data channel having a plurality of data paths is operatively connected to the transducer to receive data read from the storage medium by the transducer, or operatively connected to receive data demodulated by the receiver or base band data received by the receiver. Preferably, each of the data paths has a differing parameter value. An error checking unit checks customer and redundancy data from each of the data paths. A selecting unit, which is responsive to the error checking unit, selects data from one of the data paths. In a preferred embodiment, the data stored on a storage medium includes a data field and an error correcting code field, and the customer and redundancy data from each of the data paths is checked using a calculated error correcting code sydrome.