Patents Examined by W. Chris Kim
  • Patent number: 6351339
    Abstract: A disk medium includes a substrate and a designed topography of individually magnetizable features formed on the surface of the substrate. At least a portion of the disk topography is formed from an etched layer of magnetizable material deposited on the surface of the substrate. An information storing and retrieving system records information on the disk medium magnetically and reads the recorded information optically or magnetically. The information stored in the disk is of the form of bits each represented by a magnetic field established in the features. The direction of the magnetic field can be in a direction other than the bitstream direction, with the magnetic storing and retrieving system having a pair of non-parallel heads adapted to recognize this direction as representative of discrete logic levels formulating the basis of a non-binary storage system having significantly increased storage density.
    Type: Grant
    Filed: May 11, 1998
    Date of Patent: February 26, 2002
    Assignee: Ronni Corporation
    Inventor: Ronny Bar-Gadda
  • Patent number: 6266201
    Abstract: In a data recording system utilizing multiple channels and data blocks wherein the data blocks are read subsequent to being written so as to check for errors, the data blocks are rewritten according to a method to provide for rewriting only the defective data blocks. The blocks may be rewritten on other than their original channels. Channels for rewriting are determined by selecting a channel with a highest current block number so that data is rewritten in a channel which has been able to write and verify the most of its original blocks. Error checking is continued in a channel even after finding of an error in that channel. Data blocks of the frames may be skewed between the channels at a beginning of the frame. A ring counter output is applied to break a deadlock where a block is continously rewritten on a failing channel.
    Type: Grant
    Filed: August 19, 1998
    Date of Patent: July 24, 2001
    Assignee: Tandberg Data Asa
    Inventors: Ole Christian Dahlerud, Rolf Jahren, Arne Adli
  • Patent number: 6252734
    Abstract: An arrangement for reproducing an electric signal from a track on a magnetic record carrier (2) includes a magnetic read head (1) for reading from the track an electric signal and for supplying the electric signal to an output, and automatic equalizer filter (5), including transconductance-capacitor filter (6). The transc-filter (6) has a tuning signal input (8). The equalizer filter (5) has a control signal input (15) and is adapted to automatically equalize the electric signal read from the track in response to a control signal supplied to its control signal input, and to supply an equalized output signal at its output (12). The tuning signal input of the transc-filter is coupled to the control signal input of the equalizer filter. The arrangement further includes a control signal generator (13,16) having an output (16) coupled to the control signal input (15) of the equalizer filter (5), the generator being adapted to generate a control signal and to supply the control signal to its output (16).
    Type: Grant
    Filed: October 13, 1994
    Date of Patent: June 26, 2001
    Assignee: U.S. Philips Corporation
    Inventors: Josephus A. H. M. Kahlman, Albert M. A. Rijckaert
  • Patent number: 6239932
    Abstract: An arrangement for recording servo signals on a magnetic tape has first and second adjoining write heads respectively driven by first and second write signals. Each write signal includes a servo signal and a bias signal, the bias signals being phase displaced periodic signals which result in the magnetic tape being magnetized alternately by the first and second write heads. This provides a sharp transition in the servo signals produced from adjoining servo tracks during read-out.
    Type: Grant
    Filed: October 20, 1998
    Date of Patent: May 29, 2001
    Assignee: OnStream, Inc.
    Inventor: Abraham Hoogendoorn
  • Patent number: 6236527
    Abstract: A disk drive with means to prevent accidental landing of a head/slider on the disk surface is described. In one embodiment a shock sensor is provided to sense external shocks received by the mechanism. During loading (positioning) of the actuator bearing the head/slider over the disk, if a shock is sensed, loading is stopped and an immediate unloading is performed to return the actuator to the withdrawn position. In another embodiment the unload operation is performed when the rotational speed of the disk is changed. In another embodiment the unload operation is performed when the rotational speed of the disk drops below a threshold. A circuit and method for detecting when the rotational speed of the disk drops below a threshold is also provided. The unloading in the various embodiments may be performed using velocity control or without velocity control.
    Type: Grant
    Filed: June 24, 1998
    Date of Patent: May 22, 2001
    Assignee: International Business Machines Corporation
    Inventors: Hiroshi Uchiike, Kenji Ogasawara, Yoshiro Amano, Masahiro Shimizu, Shusuke Kurihara, Kazunari Tsuchimto, Nobuyuki Kitazaki, Shinji Ueno, Isao Yoneda, Yuji Yokoe, Fuminori Sai
  • Patent number: 6233109
    Abstract: Proper coverage of data tracks of a magnetic tape in a magnetic tape drive is ensured by providing a head assembly having a set of read heads configured such that at least one of the read heads reads a desired data track as the magnetic tape moves across the head assembly. At least one of the read heads reads the desired data track by creating lateral differential motion of the head assembly with respect to the longitudinally extending data tracks of the magnetic tape. The differential motion is either created by tracking irregularities between the head assembly and the magnetic tape or by dithering or wobbling the head assembly with respect to the magnetic tape. In operation, a controller selects one of the read data signals generated by the read heads to generate a read back signal. The read back signal is the read data signal from the at least one of the two read heads reading the desired data track.
    Type: Grant
    Filed: January 11, 1999
    Date of Patent: May 15, 2001
    Assignee: Storage Technology Corporation
    Inventor: Hartvig E. Melbye
  • Patent number: 6229661
    Abstract: This invention provides a digital data recording and reproducing apparatus and a digital data reproducing apparatus for recording data to a recording medium which can handle instrumental data as the data. In the digital data recording and reproducing apparatus according to the invention, in parallel with the writing of data to a magnetic tape, the written data is read. An error correction code of the read data is decoded and whether errors exceeding an error correcting ability which the code has exist or not is checked. In case of handling normal data, in this case, the same data is rewritten by a retrying process. In case of handling instrumental data, the retrying process is not performed and subsequent to the data having uncorrectable errors, the next data is written. In case of reading data as well, data in which uncorrectable errors exist is also read and transferred as it is.
    Type: Grant
    Filed: May 25, 1999
    Date of Patent: May 8, 2001
    Assignee: Sony Corporation
    Inventor: Takafumi Abe
  • Patent number: 6226138
    Abstract: A method of detecting and correcting reading errors of track identification (TID) of a magnetic data storage disk. The method comprises a means of constructing a encoded TID which is derived from generalized Gray code. The encoded TIDs have a distance of D between the adjacent code words, and a distance of at least 2D between non-adjacent code words within a band of M TIDS. The encoded TIDs can correct up to (D−1)/2 errors. The method also comprises means of encoding and decoding TIDS, and means of detecting and correcting errors with encoded TIDs.
    Type: Grant
    Filed: September 29, 1998
    Date of Patent: May 1, 2001
    Assignee: International Business Machines Corporation
    Inventors: Mario Blaum, William John Kabelac, Mantle Man-Hon Yu
  • Patent number: 6226137
    Abstract: A read system for receiving information from a storage medium and for supplying a signal to circuitry external to the read system is disclosed. The read system includes a bias current generator, individual channel circuitry, and preamplifier circuitry. The individual channel circuitry further includes a first and a second magnetoresistive element. A plurality of transistors are connected to the first and the second magnetoresistive element and are cross-coupled to each other to cancel out any noise arising from a mismatch of the first and the second magnetoresistive element. The preamplifier circuitry further includes a first gain stage and a second gain stage separated by a first and a second capacitor. The first and the second capacitors permit an AC signal from the first gain stage to the second gain stage, while blocking unwanted DC signals which are necessary to properly bias the first and the second MR element.
    Type: Grant
    Filed: April 2, 1999
    Date of Patent: May 1, 2001
    Assignee: Agere Systems Guardian Corp.
    Inventor: Tuan V. Ngo
  • Patent number: 6226136
    Abstract: A system and method are disclosed for reading data from a magnetic disk. The method includes generating a preamplified data signal by reading the magnetic state of the disk using a magnetoresistive head. The preamplified data signal is capacitively coupled to a variable gain read channel amplifier. The variable gain read channel amplifier has an input, an output, and a programmable gain. The input of the variable gain read channel amplifier has a variable gain read channel amplifier input resistance. The occurrence of a thermal asperity event is detected and an adjustment is made to the variable gain read channel amplifier input resistance to compensate for the thermal asperity event. An adjustment to the programmable gain of the variable gain read channel amplifier is made to compensate for the adjustment to the variable gain read channel amplifier input resistance.
    Type: Grant
    Filed: October 1, 1998
    Date of Patent: May 1, 2001
    Assignee: LSI Logic Corporation
    Inventor: Jenn-Gang Chern
  • Patent number: 6219195
    Abstract: Low-noise magneto-resistive (MR) pre-amplifier circuit amplifies signal from MR head. MR head is biased at optimal point by current source to generate signal. Current source is powered by regulator to reduce noise contribution from Vcc due to finite output impedance of current source. Self-biased CMOS low-noise amplifier (LNA) minimizes input-referred noised without using negative power supply. Small MOS transistor with feedback tracking loop replaces self-bias resistor which determines lower corner cutoff frequency. This facilitates use of large-value resistor, thereby enabling on-chip integration of DC blocking input capacitor. Gm—Gm amplifier configuration increases gain bandwidth product and minimizes parasitic effects of MOS transistors.
    Type: Grant
    Filed: January 29, 1998
    Date of Patent: April 17, 2001
    Assignee: Marvell Technology Group Ltd.
    Inventors: Gani Jusuf, Wen Fang
  • Patent number: 6219194
    Abstract: An apparatus for substantially eliminating a switching voltage transient in a magnetic recording system so as to minimize a write-to-read recovery time includes a first bias enable switch, a bias current source responsive to the first bias enable switch, an MR sensor for receiving a bias current from the current source, and a read amplifier being capacitively coupled to the MR sensor. The bias current flowing through the MR sensor produces the switching voltage transient due to the RC time constant presented by the input of the read amplifier. The apparatus includes a first compensating circuit for generating a compensating voltage transient having a polarity substantially equal and opposite to the switching transient. The first compensating circuit is electrically coupled to the MR sensor, and a superposition of the switching voltage transient and the compensating voltage transient is substantially zero.
    Type: Grant
    Filed: April 9, 1999
    Date of Patent: April 17, 2001
    Assignee: Guzik Technical Enterprises
    Inventors: Anatoli B. Stein, Serguei Pantchenko
  • Patent number: 6208480
    Abstract: A data storage apparatus is provided in which the multiple disc surfaces for a disc stack are divided into multiple rotationally spaced apart servo frames. Servo data is written on the multiple disc surfaces within radially extending servo spokes such that each disc surface includes one servo spoke within each servo frame. Within each particular servo frame the servo spokes on each of the multiple disc surfaces are offset rotationally from one another. In addition, servo control circuitry and a method of using the same to provide positional reference signals for the staggered servo format are disclosed.
    Type: Grant
    Filed: October 14, 1998
    Date of Patent: March 27, 2001
    Assignee: Seagate Technology LLC
    Inventor: Stephen C. Tigner
  • Patent number: 6208476
    Abstract: A data recording device for recording data on a magnetic tape by means of a rotational head. A buffer memory buffers the data received through input/output unit, and a controller controls the data recording device to recording and reproduce data on and from the magnetic tape. A digital signal processor (DSP) converts the data from the buffer memory into a digital audio tape recorder (DAT) format, and a memory stores the converted data from the DSP to compare with the data recorded on the magnetic tape. A recording amplifier amplifies the converted data from the DSP and delivers the amplified converted data to the rotational head to record on the magnetic tape, and a reproduction amplifier amplifies the data reproduced from the magnetic tape by the rotational head.
    Type: Grant
    Filed: November 28, 1994
    Date of Patent: March 27, 2001
    Assignee: Samsung Electronics Co., Ltd.
    Inventor: Pan-Ki Park
  • Patent number: 6204983
    Abstract: To ensure an overwrite characteristic for a magnetic disk and restrain the occurrence of waveform distortion. When record data (updated data) is recorded on a target area of a magnetic disk, a dc erase is effected to thereby ensure a requested overwrite characteristic. Next, erasing data of a constant frequency is recorded i.e., an intermediates wavelength erase is accomplished. Then, the record data is recorded. Since the erasing data is recorded before the recording of the record data, a magnetized pattern corresponding to the erasing data is formed over a recording layer (magnetic film) as a bed and waveform distortion is restrained from occurring due to the execution of the dc erase alone.
    Type: Grant
    Filed: October 19, 1998
    Date of Patent: March 20, 2001
    Assignee: Sony Corporation
    Inventor: Hajime Ito
  • Patent number: 6204981
    Abstract: An additional information f2a previously superimposed repeatedly four times with a period shorter than the decoding period of a spread information on an information signal f1a by way of spectral spread is detected four times by way of an additional information signal detection section by way of inversion spread based on a spectrally spread PN signal f5a from a PN generation section, the coincidence detection section confirms coincidence of four detection results, and thus the superimposition of the additional information f2a is finalized, therefore the additional information f2a is detected within a short time because of a short period of the spectral spread, the additional information f2a is detected with high detection accuracy with a small spread gain by way of confirming the coincidence of four detections, and a write section can perform write inhibition properly based on detection of the additional information f2a.
    Type: Grant
    Filed: February 27, 1998
    Date of Patent: March 20, 2001
    Assignee: Sony Corporation
    Inventors: Akira Ogino, Nozomu Ikeda
  • Patent number: 6204982
    Abstract: A method and apparatus for protecting against overwrite and misread errors caused by cartridge movement is disclosed. The apparatus comprises a read/write head and a read-write protection switch in electrical communication with the read-write head wherein the read-write protection switch generates an electrical signal upon movement of the media cartridge that disables the read/write head. The method of misread and overwrite protection comprises: detecting movement of the cartridge shell; disabling read/write heads; identifying whether the media drive was in the process of reading from or writing to the media cartridge; if the media drive was writing to the storage medium when the cartridge shell is moved, generating a write fault interrupt; and if the media drive is reading from the storage medium when the cartridge shell is moved, generating a read fault interrupt. A removable media cartridge having a push member and an abutment surface is also disclosed.
    Type: Grant
    Filed: June 12, 1998
    Date of Patent: March 20, 2001
    Assignee: Iomega Corporation
    Inventors: Troy Larsen, Jason Dewey, Weimin Pan
  • Patent number: 6201655
    Abstract: A magnetic disk drive has magnetic disks having tracks and a number of sectors forming each track. The tracks have an ID few track format and the drive is divided into a plurality of notches. The drive also includes a memory and a defect sector list, sector replacement list, defect track list and replacement track list, each of which is stored in the memory. Defective sectors and tracks in each notch are slipped during formatting, and further defective sectors and tracks detected subsequent to the formatting are skipped. Spare sectors in the notch are provided in a spare region to accommodate the slipped and skipped sectors and tracks, respectively. The defective sector list is supervised as a two stage table to reduce the required memory size for maintaining the list and to decrease the time required for searching the list.
    Type: Grant
    Filed: September 17, 1998
    Date of Patent: March 13, 2001
    Assignee: Hitachi, Ltd.
    Inventors: Mitsunobu Watanabe, Tsuneo Hirose, Atsushi Takayasu, Yuji Yamane, Yusuke Mizuno
  • Patent number: 6201656
    Abstract: A hard disk drive prevents a data read error by optimizing a bias current supplied to an MR-element. Signal patterns of given amplitudes are written in a data area of the recording media, and sample-and-hold values of a read signal in the above signal patterns are read and stored while changing the bias current supplied to a selected MR-element. The stored sample-and-hold values are searched to select a sample-and-hold value equal to the amplitude of the signal patterns written in the data area, and the bias current supplied to the MR-element is determined as an optimal value to obtain the selected sample-and-hold value. The optimal value of the bias current may be written in a maintenance area of the recording media and is then read upon power up of the hard disk drive.
    Type: Grant
    Filed: March 4, 1999
    Date of Patent: March 13, 2001
    Assignee: Samsung Electronics Co., Ltd.
    Inventor: Sang-Eon Go
  • Patent number: 6201653
    Abstract: A magnetic-head write-driver circuit includes a write-driver circuit and a by-pass driver circuit coupled in parallel to a signal path between the input and the output of the magnetic-head write-driver circuit. The write-driver circuit receives an input signal having transitions and outputs a first write signal related to the input signal. The by-pass driver circuit outputs an assist signal that is coupled to the first write signal to form an output write signal. The assist signal is related to transitions of the first write signal and assists in shortening reversal time of the transitions of a write signal by producing “overshoots” in the write signal at the time of the transitions. Additionally, the assist signal assists in charging and discharging a parasitic capacitance associated with an output of the magnetic-head write-driver circuit. The assist signal can add a current to, and/or enforce a voltage on, the first write signal to form the output write signal.
    Type: Grant
    Filed: June 12, 1998
    Date of Patent: March 13, 2001
    Assignee: International Business Machines Corporation
    Inventors: John T. Contreras, Klaas Berend Klaassen, Jacobus van Peppen