Patents Examined by Dan I Davidson
  • Patent number: 7502185
    Abstract: Method and system for determining spin pad length in a data storage system. The data storage system has a data storage medium having at least one track for storing a plurality of data sections, a timing reference mark for the at least one track, and a recording head for writing the plurality of data sections on and for reading the plurality of data sections from the data storage medium. The data storage system further has a spin pad length determining mechanism for determining the length of a spin pad to be written on the at least one track as a function of distance from the timing reference mark during an operation of writing a data section on the at least one track. By writing spin pads of proper length on the at least one track, the total space occupied by the spin pads on the at least one track is minimized, thus providing additional space to store data.
    Type: Grant
    Filed: September 10, 2004
    Date of Patent: March 10, 2009
    Assignee: Seagate Technology, LLC
    Inventors: Daniel Joseph Coonen, Kendall Hayne Fung
  • Patent number: 7486457
    Abstract: A method and apparatus for predicting write failure resulting from flying height modulation and initiating re-writing of data upon occurrence of the predicted write failure is disclosed. According to the present invention, if the slider or transducer flying height modulates during the write process, such modulation is detected, and a rewrite of the same data is forced. A write reassign may be initiated when a thermal signal exceeding the predetermined threshold is detected during the rewrite and/or a read/verify may be initiated after the rewrite.
    Type: Grant
    Filed: February 15, 2002
    Date of Patent: February 3, 2009
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: David H. Jen, Mike Suk
  • Patent number: 7460323
    Abstract: A method for automatically characterizing non-linearities of a perpendicular read-back signal of a recording system is disclosed. The method includes using dibit extraction to obtain a read-back signal having a main pulse and a plurality of echoes where the read-back signal exhibits a baseline shift. An area under the first echo is integrated to obtain a first area where the integrating subtracts any baseline shift area within the first echo and where the first echo is associated with a first non-linearity. The method integrates an area of the read-back signal under the main pulse to obtain a second area where the integrating subtracts any baseline shift area within the main pulse. A first parameter is computed that characterizes the first non-linearity based on the first area and the second area. The method may be applied to characterize several non-linearities.
    Type: Grant
    Filed: July 27, 2006
    Date of Patent: December 2, 2008
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventor: Yuan Xing Lee
  • Patent number: 7453659
    Abstract: System and method for write current drivers for inductive heads used in mass storage drives. A preferred embodiment comprises a write current circuit coupled to an inductive write head, a MOS transistor boost circuit and a matching circuit, both coupled to the write current circuit. The write current circuit provides a first current to the inductive write head, while the MOS transistor boost circuit provides a second current for a specified duration to the inductive write head when the MOS transistor boost circuit receives a control signal. The matching circuit selectively decouples a resistive element from the inductive write head when it receives the control signal. The MOS transistor boost circuit can accelerate the transition in a switching of the polarity of the write current and the matching circuit helps to reduce ringing without negatively affecting the speed of the polarity switching by decoupling when the second current is provided.
    Type: Grant
    Filed: May 1, 2006
    Date of Patent: November 18, 2008
    Assignee: Texas Instruments Incorporated
    Inventor: Indumini W. Ranmuthu
  • Patent number: 7450329
    Abstract: The present invention achieves technical advantages as a preamplifier write driver (10) having a varying common-mode output voltage. This varying common-mode output voltage also adjusts the derivative of the common-mode voltage, which is proportional to the amount of current coupled onto the MR head through parasitic capacitance. Currents of a first circuit (Q0,Q3) and a second circuit (Q1,Q2) are matched to overcome process variations and modeling errors. A pair of transresistance amplifiers (16) are driven by control lines (14) to achieve these matched currents.
    Type: Grant
    Filed: September 1, 2004
    Date of Patent: November 11, 2008
    Assignee: Texas Instruments Incorporated
    Inventor: Jeremy Robert Kuehlwein
  • Patent number: 7446968
    Abstract: The method and architecture improve the robustness of a synchronization system through a minimum latency loop, for Hard Disk Drives (HDD), for example, wherein synchronous detection processing is performed for timing recovering of a correct sampling phase and frequency and by a first acquisition step of a known preamble signal pattern, for generating a timing periodic signal, followed by a second tracking step, for recovering phase, frequency and gain sampling errors of the synchronization signal including a header followed by an unknown data content. Advantageously, a feedback loop including a numeric preamble generator (NPG) is provided for obtaining a reduced latency in the acquisition phase. The NPG stores preamble values for different phase offset.
    Type: Grant
    Filed: July 25, 2005
    Date of Patent: November 4, 2008
    Assignee: STMicroelectronics S.r.L.
    Inventors: Davide Giovenzana, Angelo Dati, Augusto Andrea Rossi
  • Patent number: 7443623
    Abstract: Selection of servo signals for peak detection of timing based servo tracks of magnetic tape for lateral positioning of heads relative to the magnetic tape. Servo signals from magneto-resistive servo read head(s) reading a magnetic tape are digitized by analog to digital converter(s); digital peak measurement apparatus is configured to sense the digital converter(s), and provide positive peak values and negative peak values of the digitized servo signals; and control apparatus is configured to determine the greater of the provided positive peak values or negative peak values, and select servo signals having the greater values for a servo channel. Servo apparatus is configured to respond to the selected servo signals to control the lateral positioning of the servo read head(s).
    Type: Grant
    Filed: March 13, 2008
    Date of Patent: October 28, 2008
    Assignee: International Business Machines Corporation
    Inventors: Nhan Xuan Bui, Ernest Stewart Gale, Eiji Ogura, David Lee Swanson
  • Patent number: 7443624
    Abstract: A method for recording data freshness degrees by a tape drive is disclosed. During the recording of a set of data and a data freshness degree associated with the set of data a tape recording medium, a determination is made as to whether or not a fault occurs during the recording. In response to a determination that a fault occurs during the recording, a data freshness degree of data within a faulty portion on the tape recording medium is obtained. The data freshness degree of the set of data is then immediately recorded before the faulty portion on the tape recording medium. The data freshness degree is higher than the data freshness degree of data within the faulty portion.
    Type: Grant
    Filed: February 13, 2003
    Date of Patent: October 28, 2008
    Assignee: International Business Machines Corporation
    Inventor: Hiroshi Itagaki
  • Patent number: 7440211
    Abstract: Provided is a method and apparatus for adaptively controlling the timing of servo pulses in a disk drive in consideration of the amount of spindle jitter generated when a disk rotation speed is changed. The method of controlling the timing of a sector pulse for write operation includes: measuring a spindle jitter value in a data write mode; generating a timing correction value of a sector pulse, which indicates a position of a sector where data is written, according to the measured spindle jitter value; and generating a sector pulse by reflecting the timing correction value of the sector pulse.
    Type: Grant
    Filed: May 16, 2005
    Date of Patent: October 21, 2008
    Assignee: Samsung Electronics Co., Ltd.
    Inventors: Jae-deog Cho, Sang-hun Lee
  • Patent number: 7440209
    Abstract: A communications circuit comprises a first filter having a first corner frequency that is programmable. A data type identifier tracks first and second types of data flowing through the communications circuit. A control module communicates with the first filter and the data type identifier and adjusts the corner frequency of the first filter based on the first and second types of data.
    Type: Grant
    Filed: July 20, 2005
    Date of Patent: October 21, 2008
    Assignee: Marvell International Ltd.
    Inventor: Pantas Sutardja
  • Patent number: 7436609
    Abstract: An apparatus, system, and method are disclosed for controlling gain in a magnetic media read channel. In one embodiment, a sampling module provides an asynchronous digital stream corresponding to encoded signals on a streaming magnetic medium, a stream synchronization module converts the asynchronous digital stream to a synchronous digital stream, and a gain control module processes the asynchronous digital stream and provides a gain control signal concurrent to synchronization of the asynchronous digital stream. The described apparatus, method, and system enables calibration of a read channel using a calibration signal (such as a VFO waveform) of shorter duration than attainable with currently available calibration means and methods.
    Type: Grant
    Filed: December 15, 2004
    Date of Patent: October 14, 2008
    Assignee: International Business Machines Corporation
    Inventor: Robert Allen Hutchins
  • Patent number: 7436612
    Abstract: A calculating unit calculates an interval time from a detection of a servo sync mark until a detection of an adjacent servo sync mark, for all servo sync marks on a track of a disk-shaped recording medium. A measuring unit measures, based on the calculated interval time, a deviation amount between a link interval time that represents the interval time between a servo sync mark recorded first and a servo sync mark recorded last and an ideal interval time that represents the link interval time when it is assumed that all the servo sync marks on the track are written at equal intervals.
    Type: Grant
    Filed: December 22, 2005
    Date of Patent: October 14, 2008
    Assignee: Fujitsu Limited
    Inventors: Yoshifumi Obara, Takao Abe, Takeshi Hara
  • Patent number: 7430085
    Abstract: A signal processing device having a feature of analog-to-digital converting a burst signal has a feature of selecting data bus to notify a disk control device 2 of a conversion result via an NRZ data bus. The disk control device 2 includes means for storing the result of the analog-to-digital conversion of said servo positional signal. The positional signal of a head of the disk device is digitalized in an R/W channel. Sampling for digital conversion is performed in only a window which is defined only in the vicinity of peaks of the positional signal. The values of peaks which are obtained by sampling are averaged by an averaging circuit. This enables the influence of noise occurred outside of the window to be eliminated. Although the noise in the window is sampled, its adverse influence is suppressed by the averaging processing.
    Type: Grant
    Filed: August 22, 2006
    Date of Patent: September 30, 2008
    Assignee: Hitachi Global Storage Technologies Japan, Ltd.
    Inventors: Motoyasu Tsunoda, Yukie Miyazawa, legal representative, Hitoshi Ogawa, Ryutaro Horita, Takashi Nara, Masatoshi Nishina, Katsumi Yamamoto, Shoichi Miyazawa
  • Patent number: 7430083
    Abstract: A method for monitoring a data storage medium is provided in which a virtual head fly profile is measured. In addition, a data storage device for implementing the monitoring method is provided.
    Type: Grant
    Filed: April 2, 2003
    Date of Patent: September 30, 2008
    Assignee: Seagate Technology LLC
    Inventors: David Loh, SanYuan Liew, Myint Ngwe, FongKheon Chong, EngHock Lim
  • Patent number: 7423828
    Abstract: Method and apparatus for off-track write error recovery. A storage medium is provided with at least first and second tracks, and a write protected status is assigned to the second track to inhibit subsequent writing of data thereto in relation to a position error detected during writing of data to the first track. Preferably, a third track is disposed between the first and second tracks. The position error is preferably characterized as a first position error, and a write fault condition is declared during the writing of data to the first track in relation to a second position error different from the first position error. Data write operations are preferably performed on additional tracks while the write protected status of the second track is maintained. In this way, dual-sided encroachment or other track squeezing effects are reduced.
    Type: Grant
    Filed: April 6, 2006
    Date of Patent: September 9, 2008
    Assignee: Seagate Technology LLC
    Inventors: Bruce D. Emo, Peter S. Harllee, III
  • Patent number: 7423829
    Abstract: A hard disk drive with a control circuit that controls a heating element in a head of the drive. The heating element is driven by a voltage. The control circuit varies the voltage during read and write operations of the drive. The voltages are varied to minimize fluctuations in the flying height of the drive during the write operations.
    Type: Grant
    Filed: March 22, 2006
    Date of Patent: September 9, 2008
    Assignee: Samsung Electronics Co., Ltd.
    Inventors: Hoyul Bang, Sang Y. Lee
  • Patent number: 7423825
    Abstract: A disk unit is capable of detecting a track, the track width of which deviates from a normal value, with high accuracy at high speed. A HDD includes a read head, a disk and defective-track detecting part. The disk has servo data including bursts A, B written thereon. The servo data is used to position the read head to a track center. The defective-track detecting part detects a defective track as below. The sum of the amplitude of bursts A and B, which have been read by the read head by one read operation, is divided by the amplitude of a burst C or D to obtain a compared value. If the compared value deviates from a criterion by a specified percentage or more, it is judged that the track width of a track is abnormal. Since bursts A through D are written without trimming, the size of bursts A through D in the track width direction are kept constant regardless of the track width. Accordingly, a gap G fluctuating in accordance with the track width is formed in the radial direction between bursts A and B.
    Type: Grant
    Filed: June 29, 2005
    Date of Patent: September 9, 2008
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Naoki Shimamura, Osama Takazawa, Kaoru Umemura, Kazuhiko Washizu
  • Patent number: 7417814
    Abstract: A magnetic recording device comprising a magnetic recording medium, a read-write channel for modulating write data, writing it on the magnetic recording medium, reading data from the magnetic recording medium, and demodulating the read data, and a processor for supplying the write data to the read-write channel and being supplied with the read data from the read-write channel. The processor supplies to the read-write channel a microdefect detection pattern having a first pattern for generating a consecutive magnetization inversion during writing and a second pattern for generating, during reading, a signal having a S/N ratio higher than the signal produced by the first pattern, the read-write channel modulates the microdefect detection pattern, writes it to the magnetic recording medium, reads the microdefect detection pattern, which was written, from the magnetic recording medium, and conducts abnormality detection of the microdefect detection pattern, which was read out.
    Type: Grant
    Filed: August 5, 2005
    Date of Patent: August 26, 2008
    Assignee: Fujitsu Limited
    Inventor: Yuichiro Yamazaki
  • Patent number: 7411753
    Abstract: A disk drive of a perpendicular magnetic recording system has a magnetization test function, for testing the magnetized state of a write head. The disk drive is provided with a write driver and a head amplifier unit. The write driver supplies a write current to the write head, for perpendicular magnetic recording. The degaussing unit degausses the write head.
    Type: Grant
    Filed: August 10, 2005
    Date of Patent: August 12, 2008
    Assignee: Kabushiki Kaisha Toshiba
    Inventor: Yuji Sakai
  • Patent number: 7411755
    Abstract: A write driver system comprises first switching devices that generate gate drive signals. A write driver circuit includes second switching devices that are controlled by the gate drive signals. The second switching devices have higher voltage stress thresholds than the first switching devices and wherein the second switching devices have slower switching times than the first switching devices.
    Type: Grant
    Filed: August 28, 2006
    Date of Patent: August 12, 2008
    Assignee: Marvell International Ltd.
    Inventors: Farbod Aram, Pantas Sutardja