Patents Examined by Dan I Davidson
  • Patent number: 7133232
    Abstract: In an apparatus for recording and regenerating data, a pass metric is calculated based on a likelihood converted from a previous calculation result iteratively until all pass metrics of the same data recorded many times on a recording medium are calculated, and then data recorded on the recording medium is decoded.
    Type: Grant
    Filed: April 28, 2005
    Date of Patent: November 7, 2006
    Assignee: Fujitsu Limited
    Inventors: Masakazu Taguchi, Akihiro Itakura, Akiyoshi Uchida
  • Patent number: 7130138
    Abstract: A system to ensure written data integrity in a data storage device that is operating outside of predefined normal operating conditions is disclosed. The system includes an environmental stress monitoring module operable to identify data storage device operation in an environmental stress condition and a write integrity check module for verifying written data integrity during data storage device operation in the environmental stress condition. The system and method of data protection provides a means of ensuring written data integrity without sacrificing performance during normal drive operational environmental conditions.
    Type: Grant
    Filed: December 15, 2003
    Date of Patent: October 31, 2006
    Assignee: Seagate Technology LLC
    Inventors: CheeWai Lum, YeowWeoi Yek, LianYong Tan
  • Patent number: 7126772
    Abstract: Provided is a data storage device in which servo track pitch varies within a predetermined region in a radial direction of a disk-shaped storage medium.
    Type: Grant
    Filed: January 24, 2005
    Date of Patent: October 24, 2006
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Manabu Saikawa, Hirofumi Yanase
  • Patent number: 7119975
    Abstract: A position of a moveable object may be encoded and indicated by a skew-tolerant Gray code on the object. Skew-tolerant Gray codes have the property that consecutive code words differ in only one co-ordinate position, and the additional property that, in each consecutive group of three consecutive code words, the first and third code words differ in only two adjacent coordinate positions.
    Type: Grant
    Filed: December 12, 2003
    Date of Patent: October 10, 2006
    Assignee: Hitachi Global Storage Technologies-Netherlands BV
    Inventors: Mario Blaum, Bruce Alexander Wilson
  • Patent number: 7116504
    Abstract: An apparatus, method, and system for providing dc offset reduction in a communications channel include two or more feedback loops to generate dc offset correction signals, which in turn are combined with an input analog signal and a processed digital signal thereby reducing dc offset. Each feedback loop may include an adaptive filter. At least one feedback loop may be responsive to an error signal that represents the difference between the delayed input of a first detector, and its output. Further, the dc offset correction signal, partially delayed, may be added to the error signal, thereby improving the response time of the dc offset correction loop.
    Type: Grant
    Filed: December 15, 2003
    Date of Patent: October 3, 2006
    Assignee: Marvell International Ltd.
    Inventor: Mats Oberg
  • Patent number: 7113356
    Abstract: A dynamic threshold detector for a servo writer/detector in a magnetic storage system with a magnetic medium comprises a detector that receives data from the magnetic medium and that selects one of a first condition and a second condition based on at least one of an amplitude, a sign and bit transitions of the data. A threshold selector selects a first set of thresholds when the first condition is selected by the detector and a second set of thresholds when the second condition is selected by the detector. The data includes pairs of numbers with a first number and a a second number each having one of a positive sign and a negative sign and wherein the detector selects the first condition when the signs of the pairs are the same and the second condition when the signs of the pairs are different.
    Type: Grant
    Filed: May 30, 2003
    Date of Patent: September 26, 2006
    Assignee: Marvell International Ltd.
    Inventor: Zining Wu
  • Patent number: 7113359
    Abstract: Disclosed are methods and circuits for impedance-controlled write drivers using matched impedance control circuits coupled in parallel with a magnetic write head.
    Type: Grant
    Filed: December 9, 2003
    Date of Patent: September 26, 2006
    Assignee: Texas Instruments Incorporated
    Inventors: Motomu Hashizume, Naoko Jinguji
  • Patent number: 7110198
    Abstract: A write driver system comprises a control circuit that includes first switching devices and that generates gate drive signals. A write driver circuit includes second switching devices that are controlled by the gate drive signals from the control circuit. The second switching devices have higher voltage thresholds than the first switching devices. The second switching devices have slower switching times than the first switching devices.
    Type: Grant
    Filed: April 1, 2004
    Date of Patent: September 19, 2006
    Assignee: Marvell International Ltd.
    Inventors: Farbod Aram, Pantas Sutardja
  • Patent number: 7095575
    Abstract: A self-servo reference signal including a timing pattern and an oblique phase pattern is transferred in advance on a magnetic disk 1 by magnetic printing. A phase difference detection section 13 detects a phase difference between the two patterns to detect the position of a magnetic head 2. A burst signal generated by a record signal generation section 14 is recorded in a region of the magnetic disk 1 where no self-servo reference signal is recorded. A track pitch calculation section 11 determines a relationship between the reproduction output of the burst signal detected by a reproduction signal processing section 12 and the phase difference detected by the phase difference detection section 13, thus calculating an optimum data track pitch.
    Type: Grant
    Filed: September 2, 2004
    Date of Patent: August 22, 2006
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Keizo Miyata, Hiroshi Kohso, Makoto Kimura, Tatsuaki Ishida
  • Patent number: 7095576
    Abstract: A method and apparatus for controlling a write current capable of improving an adjacent track erasure (ATE) property of a hard disk drive. The method for controlling the write current in a hard disk drive includes applying overshoot current and write current to a head to write data on a disk, waiting for a predetermined time to pass, with the predetermined time being determined according to a thermal pole tip protrusion (TPTP) property of the head, and reducing the overshoot current and the write current upon passing of the predetermined time. Accordingly, since the overshoot current and the write current are decreased at the time of the TPTP being saturated, it is possible to effectively improve an ATE property of the hard disk drive.
    Type: Grant
    Filed: September 17, 2004
    Date of Patent: August 22, 2006
    Assignee: Samsung Electronics Co., Ltd.
    Inventors: Jong-yoon Kim, Jae-deog Cho, Seong-hwan Yu, Jin-wan Jun
  • Patent number: 7092179
    Abstract: A write precompensation amount setting method and apparatus comprise a function detecting the respective head characteristics with an electric current used at an ordinary temperature and a irregular electric current, and a function setting an optimum write precompensation amount at a low temperature according to the detected head characteristics. As a result, a write precompensation amount is corrected according to the characteristics of the normal current and the irregular current, and a write precompensation amount is determined, so that the write precompensation amount with higher accuracy than that with a conventional technique can be determined.
    Type: Grant
    Filed: December 5, 2003
    Date of Patent: August 15, 2006
    Assignee: Fujitsu Limited
    Inventor: Hidetake Yamanouchi
  • Patent number: 7092180
    Abstract: An asymmetry-reducing circuit adapted to process an input signal having positive and negative pulses of different amplitudes and generate a corresponding balanced signal having positive and negative pulses of substantially uniform amplitudes. The asymmetry-reducing circuit balances the input signal by providing signal contributions corresponding to the second and third orders of the input signal. In a representative embodiment, the asymmetry-reducing circuit includes a differential amplifier and a plurality of arrayed MOS transistors connected to its inputs and outputs such that source-to-drain conductance of the transistors provides input and feedback resistances to the amplifier. A switch set selectively couples the fingers (gates) of the transistors to the input signal to modulate the source-to-drain conductance with said signal such that the input and feedback resistances change in a complementary manner.
    Type: Grant
    Filed: April 1, 2004
    Date of Patent: August 15, 2006
    Assignee: Agere Systems Inc.
    Inventor: Stephen J. Franck
  • Patent number: 7085083
    Abstract: A system and method for testing the stroke and frequency response of a micro-actuator is disclosed. A dynamic parameter tester writes two concentric tracks on a noise free portion of a magnetic storage medium. A magnetic read/write head and a micro-actuator is positioned between the two concentric tracks. An initial oscillating voltage is applied at a first frequency to the micro-actuator while reading back a signal from the two concentric tracks. A stroke characteristic of the micro-actuator is calculated based in part on the read-back signal. The initial oscillating voltage is determined from previous tests. The first stroke characteristic of the micro-actuator is based on a time-averaged amplitude of the first signal. The two concentric tracks are written at a pre-determined pitch.
    Type: Grant
    Filed: December 5, 2003
    Date of Patent: August 1, 2006
    Assignee: SAE Magnetics (H.K.) Ltd.
    Inventors: Li-Yan Zhu, Chao-Hui Yang, Xiaofeng Zhang, Yen Fu, Ellis T. Cha
  • Patent number: 7079337
    Abstract: Embodiments of the present invention relate to detecting a flying high state in which a head/slider is flying stably at a high flying position, and then to restore the head/slider to a normal flying position. The detection is made by detecting a read output of a head using a head output detector, and by detecting a gain of a VGA using a gain detector. A control unit uses a value measured in a normal flying state as a reference value to compare a detected value with the reference value. If the compared values differ from each other, the control unit judges that a flying high state has occurred. The control unit, therefore, moves the head/slider to the vicinity of the innermost circumferential track of the disk, or unloads the head/slider.
    Type: Grant
    Filed: September 17, 2004
    Date of Patent: July 18, 2006
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Akira Tokizono, Chikako Sasaki, Kenji Okada
  • Patent number: 7042667
    Abstract: A data reader is arranged to read data from a data-holding medium, said data being arranged into a plurality of data items each containing user data and non-user data, with said non-user data including one or more synchronisation fields. The data reader has a read head for reading a channel of said data-holding medium to generate a data signal comprising said data items, and processing circuitry arranged to receive and process said data signals to detect synchronisation fields, including qualifying the detection of the synchronisation fields to tolerate one or more errors in those synchronisation fields. This means that the synchronisation fields can be detected more reliably, so that more of the user data is recovered.
    Type: Grant
    Filed: July 31, 2001
    Date of Patent: May 9, 2006
    Inventors: Catharine Anne Maple, Jonathan Peter Buckingham
  • Patent number: 7031089
    Abstract: A tape head assembly comprises a transducer head having plural arrays of transducing elements, the transducing elements comprising at least one of write elements and read elements. The tape head assembly further comprises a set of conditioning elements, the conditioning elements comprising at least one of write drivers and read amplifiers. Multiplexing circuitry selectively couples the conditioning elements to one of the plural arrays of transducing elements.
    Type: Grant
    Filed: December 17, 2003
    Date of Patent: April 18, 2006
    Assignee: Hewlett-Packard Development Company, L.P.
    Inventors: Lawrence A. Hansen, Ralph F. Simmons, Jr.
  • Patent number: 7027244
    Abstract: In order to account for the misplacement of a write element during a servowriting process, the width of the information being written can be varied. In a self-servowriting disk drive, for example, the write current supplied to a read/write head can be adjusted to vary the width of information, such as servo bursts, written by the head. By calibrating the head and determining the misplacement of the head while writing, an edge of a servo burst can be placed in the desired position regardless of the misplacement of the head simply by adjusting the width of the written burst. This description is not intended to be a complete description of, or limit the scope of, the invention. Other features, aspects, and objects of the invention can be obtained from a review of the specification, the figures, and the claims.
    Type: Grant
    Filed: April 5, 2004
    Date of Patent: April 11, 2006
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventor: Richard M. Ehrlich
  • Patent number: 7023631
    Abstract: A data storage device for retrieving data includes a controllably positionable head and a storage medium having servo information comprising a phase pattern having a first frequency and a PES pattern having a second frequency, the second frequency being different from the first frequency.
    Type: Grant
    Filed: June 5, 2003
    Date of Patent: April 4, 2006
    Assignee: Seagate Technology LLC
    Inventors: Huaan Zhang, Alexei Sacks
  • Patent number: 7019925
    Abstract: Reference patterns in accordance with the present invention can include variable frequency chevrons incorporated into a reference pattern on a printed media surface to improve servo demodulation. In one embodiment, the reference pattern can include one or more servo wedges having a preamble including digital information at a first frequency relative to the head when the rotatable medium is rotated at a spin speed. The servo wedges further include at least one field having a first set of a plurality of phase-bursts forming a positive chevron angle relative to the preamble and a second set of a plurality of phase-bursts forming a negative chevron angle relative to the preamble, wherein a frequency of the at least one field relative to the head when the rotatable medium is rotated at the spin speed varies between a first end of the media surface and a second end.
    Type: Grant
    Filed: April 2, 2004
    Date of Patent: March 28, 2006
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventor: Richard M. Ehrlich
  • Patent number: 7016134
    Abstract: A method of writing product servo sectors to a disk of a disk drive is disclosed. An external spiral servo writer writes a plurality of spiral tracks to the disk by actuating in a closed loop system a head positioning pin inserted into the disk drive. Each spiral track comprises a high frequency signal interrupted at a predetermined interval by a sync mark. The high frequency signal and sync marks in the spiral tracks are demodulated to maintain synchronization of a servo write clock as well as maintain the head along a circular target path while writing product servo sectors to the disk.
    Type: Grant
    Filed: September 21, 2004
    Date of Patent: March 21, 2006
    Assignee: Western Digital Technologies, Inc.
    Inventors: Vinay K. Agarwal, Jack M. Chue, Robert L. Cloke