Patents by Inventor Tetsuo Semba

Tetsuo Semba has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 7035034
    Abstract: A hard disk device includes a servo control unit that constitutes a servo loop for a head seek for performing read/write of data from/to a recording medium, a correction signal generation unit for generating a correction signal for correcting a control by the servo control unit based on an output of a predetermined sensor, and a correction signal control unit for estimating an effect of supplying the correction signal to the servo loop and for controlling whether or not the correction signal is to be supplied to the servo loop in response to a result of the estimation. Moreover, the gain of the sensor is dynamically controlled in response to the above estimation result.
    Type: Grant
    Filed: May 21, 2003
    Date of Patent: April 25, 2006
    Assignee: International Business Machines Corporation
    Inventors: Tetsuo Semba, Naoyuki Kagami, Akira Tokizono, Gaku Ikedo
  • Publication number: 20060072392
    Abstract: Embodiments of the present invention provide a way to modify the controller of a HDD head actuator to increase the error rejection capability and suppress the wideband vibration that affects the head motion. In one embodiment, a system to suppress influence of an external disturbance to an actuator comprises a controller providing a controller output as an actuator input to drive an actuator; a feedback loop to feed a head signal at an output of the actuator back as an input to the controller to produce an error signal; and a plurality of peak filters coupled to the controller and having different peak frequencies. Each peak filter has a peak filter input including the error signal, and has a peak filter output. A supervisor module is coupled with the peak filters to selectively add or delete the peak filter output of each peak filter to the actuator input to drive the actuator.
    Type: Application
    Filed: September 30, 2004
    Publication date: April 6, 2006
    Applicant: Hitachi Global Storage Technologies Netherlands, B.V.
    Inventors: Tetsuo Semba, Matthew White, Eric Baugh
  • Publication number: 20060066985
    Abstract: A data recording disk drive has a plurality of capacitive sensors, each sensor facing a surface of an associated disk, a capacitance sensing circuit for converting the sensed capacitance to a voltage representative of the distance between the sensor and the disk surface, and a feedforward controller that receives the voltage signal. The feedforward controller has a transfer function with gain and phase characteristics designed to match the transfer function from the out-of-plane disk vibration to the position of the read/write head while accounting for the effects of the sensor dynamics and the dynamics of the actuator. The output from the feedforward controller is combined with the output from the disk drive's servo feedback controller so that the effects of disk vibration on track misregistration of the head are removed from the control signal to the actuator.
    Type: Application
    Filed: September 30, 2004
    Publication date: March 30, 2006
    Inventors: Toshiki Hirano, Tetsuo Semba, Matthew White
  • Publication number: 20060066991
    Abstract: A data recording disk drive has one or more capacitive sensors for sensing out-of-plane vibration of the disk or disks. The sensors are attached to a support structure that is attached to the disk drive housing. Each sensor is associated with a disk and faces a surface of the disk near the outer perimeter of the disk and close to the recording head. The support structure can be made of a metal or a high-strength plastic and can be a separate structure mounted to the housing, or integrated as part of the single-piece housing casting. If it is metallic, as would be the case if it were integrated with the housing, then layers of insulating material separate the sensors from the support structure. A support structure that serves other functions in the disk drive can also function as the support structure for the capacitive sensors.
    Type: Application
    Filed: September 30, 2004
    Publication date: March 30, 2006
    Inventors: Toshiki Hirano, Tetsuo Semba, Matthew White
  • Patent number: 7012777
    Abstract: A data recording disk drive has a plurality of capacitive sensors, each sensor facing a surface of an associated disk, a capacitance sensing circuit for converting the sensed capacitance to a voltage representative of the distance between the sensor and the disk surface, and a feedforward controller that receives the voltage signal. The feedforward controller has a transfer function with gain and phase characteristics designed to match the transfer function from the out-of-plane disk vibration to the position of the read/write head while accounting for the effects of the sensor dynamics and the dynamics of the actuator. The output from the feedforward controller is combined with the output from the disk drive's servo feedback controller so that the effects of disk vibration on track misregistration of the head are removed from the control signal to the actuator.
    Type: Grant
    Filed: September 30, 2004
    Date of Patent: March 14, 2006
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Toshiki Hirano, Tetsuo Semba, Matthew T. White
  • Patent number: 7010653
    Abstract: A method and system to provide a command queue re-ordering method that can make the power save and reduction in acoustic noise. The command queue re-ordering method involves calculating the value of an evaluation function, Ev=A×T+(1?A)×Fun(L) (A is any number from 0 to 1, T is a latency required to execute a write command and/or read command, and Fun(L) is an evaluation function with a seek distance L) for the write command and/or read command, and selecting the write command and/or read command having the minimum value as a next command to be execute.
    Type: Grant
    Filed: April 2, 2003
    Date of Patent: March 7, 2006
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Hiroshi Uchida, Tetsuo Semba, Tomoyuki Oyama
  • Patent number: 6831809
    Abstract: A control arrangement having a feedforward system and a feedback system, a control model for generating reference position data from a feedforward control signal is separated into an original control model and a compensation filter. Gain of the feedforward control signal is compensated by a gain compensation circuit to form a feedforward control signal after compensation. The reference position data is input to a feedback controller, and a feedback control signal and feedforward control signal are input to a control object. Coefficients of the compensation filter and the gain compensation circuit are compensated on the basis of a head position trajectory obtained by actual seek operation.
    Type: Grant
    Filed: February 27, 2002
    Date of Patent: December 14, 2004
    Assignee: International Business Machines Corporation
    Inventors: Naoyuki Kagami, Kenji Okada, Tetsuo Semba, Akira Tokizono, Hiroshi Uchida, Akinori Yuba
  • Publication number: 20030231423
    Abstract: A hard disk device includes a servo control unit that constitutes a servo loop for a head seek for performing read/write of data from/to a recording medium, a correction signal generation unit for generating a correction signal for correcting a control by the servo control unit based on an output of a predetermined sensor, and a correction signal control unit for estimating an effect of supplying the correction signal to the servo loop and for controlling whether or not the correction signal is to be supplied to the servo loop in response to a result of the estimation. Moreover, the gain of the sensor is dynamically controlled in response to the above estimation result.
    Type: Application
    Filed: May 21, 2003
    Publication date: December 18, 2003
    Inventors: Tetsuo Semba, Naoyuki Kagami, Akira Tokizono, Gaku Ikedo
  • Publication number: 20030225969
    Abstract: A method and system to provide a command queue re-ordering method that can make the power save and reduction in acoustic noise. The command queue re-ordering method involves calculating the value of an evaluation function, Ev=A×T+(1−A)×Fun(L) (A is any number from 0 to 1, T is a latency required to execute a write command and/or read command, and Fun(L) is an evaluation function with a seek distance L) for the write command and/or read command, and selecting the write command and/or read command having the minimum value as a next command to be execute.
    Type: Application
    Filed: April 2, 2003
    Publication date: December 4, 2003
    Applicant: International Business Machines Corp.
    Inventors: Hiroshi Uchida, Tetsuo Semba, Tomoyuki Oyama
  • Patent number: 6614613
    Abstract: An active control mechanism and method for stabilizing a servo-controlled actuator system such as an actuator system in a data recording disk drive by compensating the vibrational modes of the actuator's arm assembly. The control mechanism has a sensing arrangement which can include one or more individual sensors attached to the actuator at locations where they generate signals in phase with the vibrational modes, and especially with all the low-frequency major vibrational modes, of the arm assembly. A control mechanism derives from the signals an adjustment signal consisting of three corrective terms—a stiffening correction, an active damping correction, and an inertia correction by a phase correction. Furthermore, high-frequency out-of-phase modes can be stabilized by appropriately shifting the phase of the signals. The adjustment signal is used in the feedback control loop to stabilize the actuator system.
    Type: Grant
    Filed: March 16, 2000
    Date of Patent: September 2, 2003
    Assignee: International Business Machines Corporation
    Inventors: Fu-Ying Huang, Naoyuki Kagami, Tetsuo Semba, Eiji Soga, Shingo Tsuda
  • Publication number: 20020159187
    Abstract: In control means having a feedforward system and a feedback system, a control model for generating reference position data yr from feedforward control signal Uff0 is separated into an original control model 22 and a compensation filter 23. Gain of feedforward control signal Uff0 is compensated by gain compensation means 24 to form feedforward control signal Uff after compensation. Data yr is input to a feedback controller 25, and feedback control signal Ufb and Uff are input to a control object 26. Coefficients of the compensation filter 23 and the gain compensation means 24 are compensated on the basis of a head position trajectory obtained by actual seek operation.
    Type: Application
    Filed: February 27, 2002
    Publication date: October 31, 2002
    Applicant: International Business Machines Corporation
    Inventors: Naoyuki Kagami, Kenji Okada, Tetsuo Semba, Akira Tokizono, Hiroshi Uchida, Akinori Yuba
  • Patent number: 6219196
    Abstract: The present invention teaches the realization of a stable feedback control by selecting an optimal notch filter in an apparatus, such as a hard disk drive, that employs a positioning apparatus, such as an actuator, for positioning an object. The present invention further teaches the derivation of a frequency characteristic of a control loop excluding a notch filter by employing a method that does not damage a positioning apparatus. The present invention further teaches the method of adjusting a notch filter in accordance with a change of the resonant frequency of an actuator caused by the temperature fluctuations to prevent any deterioration of a feedback control performance.
    Type: Grant
    Filed: September 14, 1998
    Date of Patent: April 17, 2001
    Assignee: International Business Machines Corporation
    Inventors: Tetsuo Semba, Naoyuki Kagami, Akira Tokizono
  • Patent number: 6052345
    Abstract: The invention provides a system for compensating for hard sector noise degradation of tracking error signals in an optical data storage system. The system includes a hard sector detection circuit which generates a first output signal in response to receiving a first input signal representing detection of a hard sector on a magneto-optical disk; a logic circuit which generates a second output signal in response to receiving the first output signal and a second input signal; and a tracking error signal reconstruction circuit which generates an approximated tracking error signal in response to receiving a tracking error signal and the second output signal. The invention may be embodied as hardwired circuitry or as a combination of hardware and software embodied in a computer readable medium and implemented in a digital computer.
    Type: Grant
    Filed: March 3, 1999
    Date of Patent: April 18, 2000
    Assignee: International Business Machines Corporation
    Inventors: Allen Keith Bates, Nhan Xuan Bui, Alan August Fennema, Tetsuo Semba
  • Patent number: 5936919
    Abstract: The invention provides a system for compensating for hard sector noise degradation of tracking error signals in an optical data storage system. The system includes a hard sector detection circuit which generates a first output signal in response to receiving a first input signal representing detection of a hard sector on a magneto-optical disk; a logic circuit which generates a second output signal in response to receiving the first output signal and a second input signal; and a tracking error signal reconstruction circuit which generates an approximated tracking error signal in response to receiving a tracking error signal and the second output signal. The invention may be embodied as hardwired circuitry or as a combination of hardware and software embodied in a computer readable medium and implemented in a digital computer.
    Type: Grant
    Filed: February 20, 1997
    Date of Patent: August 10, 1999
    Assignee: International Business Machines Corporation
    Inventors: Allen Keith Bates, Nhan Xuan Bui, Alan August Fennema, Tetsuo Semba
  • Patent number: 5768228
    Abstract: A method for cancelling optical servo crosstalk within an optical disk drive is disclosed. In accordance with the method and system of the present invention, the optical disk drive system includes a focus control module, a tracking control module, a variable frequency notch filter, and a lookup table. The focus control module is utilized for moving an objective lens in response to a focus error signal in order to maintain a laser beam in an in-focus condition on an optical disk. The tracking control module is utilized for moving a moving optical element in response to a tracking error signal to direct the laser beam onto a desired track position of the optical disk. The lookup table within the focus control module is utilized for storing several sets of tap coefficients for the variable frequency notch filter.
    Type: Grant
    Filed: September 9, 1996
    Date of Patent: June 16, 1998
    Assignee: International Business Machines Corporation
    Inventors: Allen Keith Bates, Alan August Fennema, Tetsuo Semba
  • Patent number: 5760991
    Abstract: A disk storage unit according to the present invention comprises a disk for storing data, a head for at least reading data stored on the disk, a controller for controlling a seek operation in which the head moves from a current track to a target track and a tracking operation in which the head tracks the target track after reaching the target track, based on a tracking error signal, and a device for adding a dc offset to the tracking error signal so that head drive power having a direction opposite that of the seek operation and corresponding to the velocity of the head in the seek operation is generated after the head has reached the target track and the seek operation has been switched to the tracking operation.
    Type: Grant
    Filed: October 28, 1994
    Date of Patent: June 2, 1998
    Assignee: International Business Machines Corporation
    Inventor: Tetsuo Semba
  • Patent number: 5504726
    Abstract: The present invention makes possible the calibration of the tracking error signal and the focus error signal repeatedly when an optical disk drive is in the normal operation mode. Errors (offset and amplitude error) of the focus error signal and the tracking error signal are detected during at least three track jumps by making use of a track jump performed once per rotation of disk in the track following mode. An offset value of the focus error signal is calculated based on the amplitude of a tracking error signal generated during at least two track jumps by adding a positive or negative offset to the original target value of the focus error signal, and values of offset and amplitude error of the tracking error signal are calculated based on a maximum value and a minimum value of a tracking error signal generated during at least one track jump without modifying the original target value of the focus error signal.
    Type: Grant
    Filed: April 6, 1994
    Date of Patent: April 2, 1996
    Assignee: International Business Machines Corporation
    Inventor: Tetsuo Semba
  • Patent number: 5323368
    Abstract: To accomplish both fast track access and low power consumption in an apparatus for recording or reading out a signal onto or from a track of a recording medium. The actuator control apparatus uses a tracking error signal (TES), which is a signal whose level varies, with the time taken for a pickup to cross one track being used as a cycle. It detects the velocity of the pickup from the time interval (Ti) of the mean level crossing by TES, and provides an actuator with a signal having a pulse width (Tf) proportional to the time interval of the mean level crossing by TES, in synchronization with the crossing of the mean level by TES.
    Type: Grant
    Filed: November 17, 1992
    Date of Patent: June 21, 1994
    Assignee: International Business Machines Corporation
    Inventor: Tetsuo Semba
  • Patent number: 5317550
    Abstract: A track access apparatus is provided by the present invention in which a reference drive signal 90 proportional to the reference acceleration of a beam spot 22 is generated according to the contents of a track counter 34. A signal 92 indicating the reference velocity of the beam spot 22 is generated by an integrator 40 in accordance with reference drive signal 90. A signal 82 indicating the position of an objective lens 20 relative to a coarse actuator 26, a signal 84 indicating a relative velocity, and a signal 94 indicating the difference between the actual velocity of beam spot 22 and a reference velocity are supplied to coarse actuator 26 and to a fine actuator 28. Reference drive signal 90 is supplied to coarse actuator 26. The present invention makes maximum use of the rapid acceleration and deceleration capability of the coarse actuator and moves the beam spot to a target track accurately at high speed.
    Type: Grant
    Filed: January 22, 1993
    Date of Patent: May 31, 1994
    Assignee: International Business Machines Corporation
    Inventor: Tetsuo Semba