Patents by Inventor Tatsuharu Kusumoto
Tatsuharu Kusumoto 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).
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Publication number: 20090015961Abstract: According to one embodiment, a disk drive (HDD) is installed in a portable electronic device. The HDD includes an actuator which supports a head such that the head is radially movable over a disk. A constant speed controller incorporated in the HDD executes constant speed control for unloading the head onto a ramp at a constant speed in accordance with a fall detection signal output from a fall detector and indicating that fall of the device has been detected. In the constant speed control, the controller drives a voice coil motor as a drive source for the actuator to make the movement speed of the head identical to a first target speed. The first target speed is set higher than a second target speed set when the head is unloaded onto the ramp in a normal state.Type: ApplicationFiled: June 18, 2008Publication date: January 15, 2009Applicant: KABUSHIKI KAISHA TOSHIBAInventor: Tatsuharu Kusumoto
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Patent number: 7206158Abstract: A reset circuit asserts a reset signal when at least a power-off detection signal or a drop detection signal is asserted. When the reset signal is asserted, an emergency unload circuit supplies a voice coil motor with a current for retracting the head to the retract area. The emergency unload circuit uses an auxiliary power supply as an operation power supply thereof.Type: GrantFiled: January 21, 2005Date of Patent: April 17, 2007Assignee: Kabushiki Kaisha ToshibaInventor: Tatsuharu Kusumoto
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Patent number: 7019939Abstract: On the basis of the position of a first target track specified by a command from a host, a CPU calculates a first offset value reflecting a track pitch that enables the adverse effects of crosstalk to be suppressed. The first offset value indicates an offset of a target position at which a head is to be actually positioned from a predetermined position on the first target track. The CPU determines a second target track, to which the target position belongs, and a second offset value on the basis of the position of the first target track and the calculated first offset value. The second offset value indicates an offset of the target position from the predetermined position on the second target track. The CPU positions the head at the target position on the determined second target track on the basis of the determined second target track position and second offset value.Type: GrantFiled: December 23, 2003Date of Patent: March 28, 2006Assignee: Kabushiki Kaisha ToshibaInventors: Tatsuharu Kusumoto, Koji Yaegashi
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Publication number: 20050264914Abstract: A reset circuit asserts a reset signal when at least a power-off detection signal or a drop detection signal is asserted. When the reset signal is asserted, an emergency unload circuit supplies a voice coil motor with a current for retracting the head to the retract area. The emergency unload circuit uses an auxiliary power supply as an operation power supply thereof.Type: ApplicationFiled: January 21, 2005Publication date: December 1, 2005Applicant: KABUSHIKI KAISHA TOSHIBAInventor: Tatsuharu Kusumoto
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Patent number: 6922302Abstract: In a head loading/unloading type disk apparatus, accurate velocity feedback control is implemented by correcting any error in a VCM velocity detection value, which is caused by a temperature change or the like. At the start of loading control for loading a head from a ramp onto a disk, a carriage is pushed against an outer-periphery stopper to set the actual velocity of a VCM to zero. In this state, a VCM velocity detection value detected by a VCM velocity detection circuit is read out. On the basis of this velocity detection value, calibration for correcting the relationship between the VCM current value and the VCM velocity detection value is performed. In the period of head positioning control after the loading, an operation using a timer is periodically performed in which the carriage is pushed against an inner-periphery stopper, the calibration is reexecuted, and the head is returned to the original head position.Type: GrantFiled: September 9, 2003Date of Patent: July 26, 2005Assignee: Kabushiki Kaisha ToshibaInventors: Tatsuharu Kusumoto, Hidetoshi Kawachi
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Patent number: 6894862Abstract: Disclosed herein is a servo system for performing head positioning control in a disk drive, thereby to move the head to a desired position on a disk. The servo system perform a learning operation, thereby calculating a learned value relating to a disk-runout, and effects servo compensation to suppress a disk-runout, by using the learned value. Further, the servo system abandons erases the learned value in a memory when an impact applied to the disk drive and exceeding a tolerance value is detected during the learning operation.Type: GrantFiled: September 3, 2003Date of Patent: May 17, 2005Assignee: Kabushiki Kaisha ToshibaInventor: Tatsuharu Kusumoto
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Patent number: 6765746Abstract: While a disk drive is operating, a retract time period, which is required for moving a head from its present position to a predetermined retract change position using a back EMF that occurs in an SPM, is determined. Upon power-off of a power supply for the disk drive, at first, a first retract operation for moving the head using the back EMF of the SPM is started. When the retract time period has elapsed after the power-off of the power supply, the first retract operation is switched to a second retract operation for moving the head onto a ramp using a charge accumulated in a retract capacitor.Type: GrantFiled: March 7, 2002Date of Patent: July 20, 2004Assignee: Kabushiki Kaisha ToshibaInventor: Tatsuharu Kusumoto
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Patent number: 6765742Abstract: In a disk storage apparatus, a CPU (2) supplies control current of a rated maximum current value to a VCM (6) at the time a head is loaded onto a disk. When the head is stopped on the head stop member, the CPU (2) controls an additional drive circuit (12) to conduct re-try processing. The additional drive circuit (12) supplies to the VCM (6) a control current whose current value is added to the rated maximum current value.Type: GrantFiled: March 22, 2001Date of Patent: July 20, 2004Assignee: Kabushiki Kaisha ToshibaInventor: Tatsuharu Kusumoto
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Publication number: 20040136109Abstract: On the basis of the position of a first target track specified by a command from a host, a CPU calculates a first offset value reflecting a track pitch that enables the adverse effects of crosstalk to be suppressed. The first offset value indicates an offset of a target position at which a head is to be actually positioned from a predetermined position on the first target track. The CPU determines a second target track, to which the target position belongs, and a second offset value on the basis of the position of the first target track and the calculated first offset value. The second offset value indicates an offset of the target position from the predetermined position on the second target track. The CPU positions the head at the target position on the determined second target track on the basis of the determined second target track position and second offset value.Type: ApplicationFiled: December 23, 2003Publication date: July 15, 2004Applicant: KABUSHIKI KAISHA TOSHIBAInventors: Tatsuharu Kusumoto, Koji Yaegashi
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Patent number: 6760183Abstract: A disk drive including a servo system that performs a learning operation for calculating a servo compensation value is disclosed. The servo system determines whether an initial learning value stored in a flash memory in advance is valid or invalid. When the initial learning value is valid, the servo system inhibits a normal learning operation from being performed. When the initial learning value is invalid, the servo system calculates a servo compensation value using the present learning value obtained by performing the learning operation.Type: GrantFiled: September 19, 2001Date of Patent: July 6, 2004Assignee: Kabushiki Kaisha ToshibaInventor: Tatsuharu Kusumoto
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Publication number: 20040047064Abstract: In a head loading/unloading type disk apparatus, accurate velocity feedback control is implemented by correcting any error in a VCM velocity detection value, which is caused by a temperature change or the like. At the start of loading control for loading a head from a ramp onto a disk, a carriage is pushed against an outer-periphery stopper to set the actual velocity of a VCM to zero. In this state, a VCM velocity detection value detected by a VCM velocity detection circuit is read out. On the basis of this velocity detection value, calibration for correcting the relationship between the VCM current value and the VCM velocity detection value is performed. In the period of head positioning control after the loading, an operation using a timer is periodically performed in which the carriage is pushed against an inner-periphery stopper, the calibration is reexecuted, and the head is returned to the original head position.Type: ApplicationFiled: September 9, 2003Publication date: March 11, 2004Inventors: Tatsuharu Kusumoto, Hidetoshi Kawachi
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Publication number: 20040042114Abstract: Disclosed herein is a servo system for performing head positioning control in a disk drive, thereby to move the head to a desired position on a disk. The servo system perform a learning operation, thereby calculating a learned value relating to a disk-runout, and effects servo compensation to suppress a disk-runout, by using the learned value. Further, the servo system abandons erases the learned value in a memory when an impact applied to the disk drive and exceeding a tolerance value is detected during the learning operation.Type: ApplicationFiled: September 3, 2003Publication date: March 4, 2004Applicant: Kabushiki Kaisha ToshibaInventor: Tatsuharu Kusumoto
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Patent number: 6661598Abstract: In a head loading/unloading type disk apparatus, accurate velocity feedback control is implemented by correcting any error in a VCM velocity detection value, which is caused by a temperature change or the like. At the start of loading control for loading a head from a ramp onto a disk, a carriage is pushed against an outer-periphery stopper to set the actual velocity of a VCM to zero. In this state, a VCM velocity detection value detected by a VCM velocity detection circuit is read out. On the basis of this velocity detection value, calibration for correcting the relationship between the VCM current value and the VCM velocity detection value is performed. In the period of head positioning control after the loading, an operation using a timer is periodically performed in which the carriage is pushed against an inner-periphery stopper, the calibration is reexecuted, and the head is returned to the original head position.Type: GrantFiled: August 15, 2002Date of Patent: December 9, 2003Assignee: Kabushiki Kaisha ToshibaInventors: Tatsuharu Kusumoto, Hidetoshi Kawachi
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Patent number: 6650499Abstract: Disclosed herein is a servo system for performing head positioning control in a disk drive, thereby to move the head to a desired position on a disk. The servo system perform a learning operation, thereby calculating a learned value relating to a disk-runout, and effects servo compensation to suppress a disk-runout, by using the learned value. Further, the servo system abandons erases the learned value in a memory when an impact applied to the disk drive and exceeding a tolerance value is detected during the learning operation.Type: GrantFiled: September 15, 2000Date of Patent: November 18, 2003Assignee: Kabushiki Kaisha ToshibaInventor: Tatsuharu Kusumoto
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Patent number: 6594102Abstract: Disclosed herein is a disk drive that can retract the head to a retract position by using a reserve power supply, when the supply of power from the main power supply is interrupted. The disk drive comprises a CPU, a control capacitor, an unload circuit, a reserve power supply, and a VCM. While the disk drive is operating normally, the CPU performs servo control, calculates a retract distance from the position of the head and determines a control value corresponding to the retract distance, by using the main power supply. The CPU converts the control value to a control voltage, which is held in the control capacitor. When the supply of power from the main power supply is interrupted, the unload circuit supplies a drive current set by the control voltage held in the control capacitor, from the reserve power supply to the VCM. The VCM moves the head to the retract position at an appropriate speed.Type: GrantFiled: June 30, 1999Date of Patent: July 15, 2003Assignee: Kabushiki Kaisha ToshibaInventors: Hiroyuki Kanda, Koji Osafune, Tatsuharu Kusumoto
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Publication number: 20030117741Abstract: A CPU performs head load control to load a head above a disk from a ramp by speed feedback control when a nonoperating state of a disk drive is released. The CPU uses a value corresponding to an amount of VCM current necessary for moving the head from a parking area on the ramp during a predetermined period of time until the first sampling time of the speed feedback control as an initial value of a control variable (initial control variable) used for the speed feedback control.Type: ApplicationFiled: September 5, 2002Publication date: June 26, 2003Inventor: Tatsuharu Kusumoto
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Publication number: 20030002196Abstract: In a head loading/unloading type disk apparatus, accurate velocity feedback control is implemented by correcting any error in a VCM velocity detection value, which is caused by a temperature change or the like. At the start of loading control for loading a head from a ramp onto a disk, a carriage is pushed against an outer-periphery stopper to set the actual velocity of a VCM to zero. In this state, a VCM velocity detection value detected by a VCM velocity detection circuit is read out. On the basis of this velocity detection value, calibration for correcting the relationship between the VCM current value and the VCM velocity detection value is performed. In the period of head positioning control after the loading, an operation using a timer is periodically performed in which the carriage is pushed against an inner-periphery stopper, the calibration is reexecuted, and the head is returned to the original head position.Type: ApplicationFiled: August 15, 2002Publication date: January 2, 2003Inventors: Tatsuharu Kusumoto, Hidetoshi Kawachi
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Patent number: 6496319Abstract: In a head loading/unloading type disk apparatus, accurate velocity feedback control is implemented by correcting any error in a VCM velocity detection value, which is caused by a temperature change or the like. At the start of loading control for loading a head from a ramp onto a disk, a carriage is pushed against an outer-periphery stopper to set the actual velocity of a VCM to zero. In this state, a VCM velocity detection value detected by a VCM velocity detection circuit is read out. On the basis of this velocity detection value, calibration for correcting the relationship between the VCM current value and the VCM velocity detection value is performed. In the period of head positioning control after the loading, an operation using a timer is periodically performed in which the carriage is pushed against an inner-periphery stopper, the calibration is reexecuted, and the head is returned to the original head position.Type: GrantFiled: August 25, 1999Date of Patent: December 17, 2002Assignee: Kabushiki Kaisha ToshibaInventors: Tatsuharu Kusumoto, Hidetoshi Kawachi
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Publication number: 20020141102Abstract: While a disk drive is operating, a retract time period, which is required for moving a head from its present position to a predetermined retract change position using a back EMF that occurs in an SPM, is determined. Upon power-off of a power supply for the disk drive, at first, a first retract operation for moving the head using the back EMF of the SPM is started. When the retract time period has elapsed after the power-off of the power supply, the first retract operation is switched to a second retract operation for moving the head onto a ramp using a charge accumulated in a retract capacitor.Type: ApplicationFiled: March 7, 2002Publication date: October 3, 2002Inventor: Tatsuharu Kusumoto
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Publication number: 20020034037Abstract: A disk drive including a servo system that performs a learning operation for calculating a servo compensation value is disclosed. The servo system determines whether an initial learning value stored in a flash memory in advance is valid or invalid. When the initial learning value is valid, the servo system inhibits a normal learning operation from being performed. When the initial learning value is invalid, the servo system calculates a servo compensation value using the present learning value obtained by performing the learning operation.Type: ApplicationFiled: September 19, 2001Publication date: March 21, 2002Inventor: Tatsuharu Kusumoto