Patents by Inventor Yasuhiko Kokami
Yasuhiko Kokami 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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Patent number: 7071640Abstract: In start-up control of a motor in which currents are caused to flow through any two of three phase coils to detect the polarity of a voltage induced in each de-energized phase, thereby determining the corresponding energized phase at start-up thereof, based on the polarity of the detected induced voltage, the levels of induced voltages are detected in addition to the polarity of the induced voltage for the de-energized phase to thereby determine the relationship between the magnitudes thereof, and the energized phase at the start-up is determined based on the relationship of magnitude between the polarity of each induced voltage and the level thereof.Type: GrantFiled: October 15, 2003Date of Patent: July 4, 2006Assignees: Renesas Technology Corporation, Hitachi ULSI Systems Co., Ltd.Inventors: Minoru Kurosawa, Kunihiro Kawauchi, Yasuhiko Kokami
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Patent number: 7054089Abstract: The present invention provides a magnetic disk storage system including a spindle motor that rotates a magnetic disk, a spindle motor drive circuit that rotatably drives the spindle motor, a magnetic head that performs reading of information on the magnetic disk, a voice coil motor that moves the magnetic head, and a voice coil motor drive circuit that drives the voice coil motor. When the magnetic head is loaded from a standby position to the surface of the magnetic disk, the rotational speed of the spindle motor is made slower than a rotational speed at a normal operation. Upon power-off, the spindle motor drive circuit is caused to carry out a stepup converter operation to thereby generate a voltage higher than a back electromotive voltage, and causes a control circuit and a drive circuit to operate by the high voltage to thereby enable speed control at the movement of the magnetic head to a predetermined standby position.Type: GrantFiled: October 24, 2003Date of Patent: May 30, 2006Assignees: Renesas Technology Corp., Hitachi ULSI Systems Co., Ltd.Inventor: Yasuhiko Kokami
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Publication number: 20060082336Abstract: A drive control device of motor capable of starting up even a motor of such a type that the polarity of induced voltage does not switch every 180° of electrical angle or the polarity, positive or negative, does not occur with accuracy without causing a reverse rotation is provided. In a start-up control of motor, the following operation is performed: a current is passed through any coils in two phases, and the polarity of voltage induced in the non-conducting phase is detected. A conducting phase at start-up is determined based on the detected polarity of induced voltage. The average value of induced voltages in non-conducting phase detected with respect to the coils in respective phases is determined. The average value and the detected induced voltages are compared with each other, and relative polarities are determined from the magnitude relation with the average value to determine a conducting phase at start-up.Type: ApplicationFiled: October 13, 2005Publication date: April 20, 2006Inventors: Minoru Kurosawa, Yasuhiko Kokami
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Publication number: 20060072237Abstract: The present invention provides a magnetic disk storage system including a spindle motor that rotates a magnetic disk, a spindle motor drive circuit that rotatably drives the spindle motor, a magnetic head that performs reading of information on the magnetic disk, a voice coil motor that moves the magnetic head, and a voice coil motor drive circuit that drives the voice coil motor. When the magnetic head is loaded from a standby position to the surface of the magnetic disk, the rotational speed of the spindle motor is made slower than a rotational speed at a normal operation. Upon power-off, the spindle motor drive circuit is caused to carry out a stepup converter operation to thereby generate a voltage higher than a back electromotive voltage, and causes a control circuit and a drive circuit to operate by the high voltage to thereby enable speed control at the movement of the magnetic head to a predetermined standby position.Type: ApplicationFiled: November 21, 2005Publication date: April 6, 2006Inventor: Yasuhiko Kokami
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Patent number: 6998801Abstract: A motor drive device which controls a spindle output predriver unit and power MOSFETs of an output stage associated with it to form a PWM signal in such a manner that a detection current formed by a DC shunt resistor and a sense amplifier and a current instruction signal coincide with each other, generates a regenerative signal obtained by giving dead times to the PWM signal, generates an energizing timing signal from the result of BEMF (back electromotive voltage) zero cross detection and generates signals for controlling on/off of power MOSFETs of three phases to thereby drive a three-phase motor, is provided with a switching characteristic adjustment unit which measures a time at which the spindle output is being transitioned and performs such feedback control that the measured time and a designated switching time coincide with each other.Type: GrantFiled: February 17, 2005Date of Patent: February 14, 2006Assignee: Renesas Technology Corp.Inventors: Minoru Kurosawa, Yasuhiko Kokami
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Patent number: 6975479Abstract: There is provided a technique for controlling drive of a voice coil motor which can select, with priority for effective reduction, any one of heat generation and EMI noise which are presumed to induce a read/write error and for simultaneously realizing the positioning control of magnetic head with higher accuracy during the tracking operation and the high speed access with shortening of the seek operation period. The magnetic disc storage apparatus introducing this technique is provided with a mode to drive with linear control a coil of the voice coil motor from both terminals and a mode to drive one terminal of coil with linear control and the other terminal with pulse width control. Thereby, the coil is driven in the drive mode of linear control during the tracking operation, while one terminal of coil is driven with linear control and the other terminal with pulse width control during the seek operation.Type: GrantFiled: May 14, 2002Date of Patent: December 13, 2005Assignee: Renesas Technology Corp.Inventors: Yasuhiko Kokami, Kenji Nishimura, Tatsuya Negishi
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Patent number: 6972918Abstract: In a magnetic disk memory device, the shifting speed of the magnetic head in time of power supply interruption is detected, and a voice coil motor is controlled in accordance with the detected shifting speed to enable the head to be shunted safely and promptly.Type: GrantFiled: May 30, 2003Date of Patent: December 6, 2005Assignees: Renesas Technology Corp., Hitachi ULSI Systems Co., Ltd.Inventors: Yasuhiko Kokami, Minoru Kurosawa
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Publication number: 20050218853Abstract: The Invention provides a motor drive semiconductor integrated circuit for driving and controlling a voice coil motor that can conduct a seek operation, a track follow operation and a settling operation through PWM control, has desired control accuracy and can be produced by a CMOS process. In a voice coil motor drive circuit (200) for executing positioning control of a magnetic head by feedback-controlling a driving current of a voice coil motor (108) for moving a magnetic head (106) over a magnetic disk for reading information from a storage track on the magnetic disk driven for rotation while a read state of the magnetic head is being monitored, head movement control such as a seek operation, a track follow operation etc, of the magnetic head is executed by PWM driving on the basis of a command value from a controller.Type: ApplicationFiled: April 5, 2005Publication date: October 6, 2005Inventor: Yasuhiko Kokami
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Publication number: 20050189891Abstract: A motor drive device which controls a spindle output predriver unit and power MOSFETs of an output stage associated with it to form a PWM signal in such a manner that a detection current formed by a DC shunt resistor and a sense amplifier and a current instruction signal coincide with each other, generates a regenerative signal obtained by giving dead times to the PWM signal, generates an energizing timing signal from the result of BEMF (back electromotive voltage) zero cross detection and generates signals for controlling on/off of power MOSFETs of three phases to thereby drive a three-phase motor, is provided with a switching characteristic adjustment unit which measures a time at which the spindle output is being transitioned and performs such feedback control that the measured time and a designated switching time coincide with each other.Type: ApplicationFiled: February 17, 2005Publication date: September 1, 2005Inventors: Minoru Kurosawa, Yasuhiko Kokami
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Publication number: 20050189892Abstract: There is provided a drive control system for sensor-less motor wherein a multi-phase sensor-less motor is driven to rotate by switching a current to be applied to a field coil of each phase depending on the rotating phase of motor and such rotating drive is controlled with the PLL control method and the sensor-less motor is driven with higher reliability. When the motor is to be driven, a desired phase is selected as the detection phase and a voltage (Eu, Ev, Ew) induced on the coil of the detection phase is detected when the power is fed for a short period of time to the field coils except for that of the detection phase. A magnetic pole position of a rotor is detected from the amplitude condition of the detected induced voltage and the power feeding phase of the motor drive is determined based on the result of detection of the magnetic pole position.Type: ApplicationFiled: May 4, 2005Publication date: September 1, 2005Inventors: Yasuhiko Kokami, Kunihiro Kawauchi, Toshiyuki Tsunoda, Reiichi Kimura
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Patent number: 6903894Abstract: A magnetic disc storage apparatus including a magnetic head for reading information from a storage track on a magnetic storage disc driven to spin, a voice coil motor for moving the magnetic head above the disc, and a magnetic head drive system for executing a position control of the magnetic head by controlling driving current of the voice coil motor by a feedback control while monitoring a state of reading the magnetic head in which the magnetic head drive system includes multi-mode driving means for executing a linear drive mode for controlling, as an analog amount, the driving current of the voice coil motor when an amount of driving to move the magnetic head is small and executing a pulse drive mode for controlling, as a digital amount, the driving current of the voice coil motor when the amount of driving to move the magnetic head is large.Type: GrantFiled: December 12, 2001Date of Patent: June 7, 2005Assignees: Hitachi, Ltd., Hitachi ULSI Systems Co., Ltd.Inventors: Yasuhiko Kokami, Kenji Nishimura, Tatsuya Negishi
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Patent number: 6900604Abstract: A drive control system, with PLL control, drives a rotatable multi-phase sensor-less motor by switching a current of a field coil of each phase depending on the rotating phase of the motor. When the moto is driven, a desired phase is selected as a datection phase, and a voltage induced on the coil of the detection phase is detected when power is fed for a predetermined time to the field coils other than the detection phase. A magnetic pole position is detected from the amplitude condition of the detected induced voltage. Based on this detection, the power-feeding phase of the motor drive is determined. Power feeding and pole position detection are performed alternately.Type: GrantFiled: November 12, 2002Date of Patent: May 31, 2005Assignees: Renesas Technology Corp., Hitachi ULSI Systems Co., Ltd., Hitachi Tohbu Semiconductor, Ltd.Inventors: Yasuhiko Kokami, Kunihiro Kawauchi, Toshiyuki Tsunoda, Reiichi Kimura
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Publication number: 20050067986Abstract: A three-phase DC motor output stage including a predriver that supplies drive voltages to power MOSFETs supplies output voltages to three-phase coils, monitors whether each of gate-to-source voltages of the power MOSFETs is greater than or equal to a predetermined voltage and thereby detects a current zero cross, and employs the output of such current zero cross detection in PLL control for controlling energization switching timing and thereby forms drive voltages of 180-degree energization. Lower hooks with a voltage minimum phase as GND and upper hooks with a voltage maximum phase as a source are set as patterns alternately repeated for every electrical angle of 60 degrees. The patterns are expressed in linear approximation to generate sine wave-like drive voltages, thereby causing sine wave-like currents to flow into the three-phase coils.Type: ApplicationFiled: September 13, 2004Publication date: March 31, 2005Inventors: Minoru Kurosawa, Yasuhiko Kokami
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Publication number: 20050036228Abstract: Currents of sine waveforms can be fed through coils by a relatively small-sized circuit, and thereby, highly dense magnetic storage can be realized with less rotation variations and a driving control circuit of a motor rotating at a low noise level can be provided. A coil of one phase of a three-phase brushless motor is driven with full amplitude at which an applied voltage becomes equal to a source voltage, and a coil of one of other phases is driven with gradually changing voltages so that a current of sine waveform is delivered, and a coil of the remaining phase is driven by feedback control so that a total current flowing through all coils becomes a predetermined current value.Type: ApplicationFiled: September 24, 2004Publication date: February 17, 2005Inventors: Reiichi Kimura, Yasuhiko Kokami, Kunihiro Kawauchi, Minoru Kurosawa, Kichiya Itagaki
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Patent number: 6801382Abstract: Currents of sine waveforms can be fed through coils by a relatively small-sized circuit, and thereby, highly dense magnetic storage can be realized with less rotation variations and a driving control circuit of a motor rotating at a low noise level can be provided. A coil of one phase of a three-phase brushless motor is driven with full amplitude at which an applied voltage becomes equal to a source voltage, and a coil of one of other phases is driven with gradually changing voltages so that a current of sine waveform is delivered, and a coil of the remaining phase is driven by feedback control so that a total current flowing through all coils becomes a predetermined current value.Type: GrantFiled: April 17, 2002Date of Patent: October 5, 2004Assignees: Renesas Technology Corp., Hitachi Tohbu Semiconductor, Ltd.Inventors: Reiichi Kimura, Yasuhiko Kokami, Kunihiro Kawauchi, Minoru Kurosawa, Kichiya Itagaki
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Patent number: 6771033Abstract: A drive control system, with PLL control, drives a rotatable multi-phase sensor-less motor by switching a current of a field coil of each phase depending on the rotating phase of the motor. When the motor is driven, a desired phase is selected as a detection phase, and a voltage induced on the coil of the detection phase is detected when power is fed for a predetermined time to the field coils other than the detection phase. A magnetic pole position is detected from the amplitude condition of the detected induced voltage. Based on this detection, the power-feeding phase of the motor drive is determined. Power feeding and pole position detection are performed alternately.Type: GrantFiled: January 14, 2003Date of Patent: August 3, 2004Assignees: Renesas Technology Corp., Hitachi ULSI Systems Co., Ltd., Hitachi Tohbu Semiconductor, Ltd.Inventors: Yasuhiko Kokami, Kunihiro Kawauchi, Toshiyuki Tsunoda, Reiichi Kimura
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Patent number: 6757129Abstract: In a magnetic disk storage apparatus, when a drive current of the voice coil motor is small, the head drive control circuit executes the linear drive mode under which the voice coil motor is driven in a linear control manner, whereas when the drive current is large, the head drive control circuit executes the pulse drive mode under which the voice coil motor is driven in a pulse width control manner. Both modes are carried out by employing a commonly-used output amplifier that is arranged as a push-pull type output circuit made of both a push-driving output transistor and a pull-driving output transistor. An operation mode of this output amplifier is set to an AB-class operation during the linear drive mode, whereas the operation mode of this output amplifier is set to a B-class operation during the pulse drive mode.Type: GrantFiled: February 25, 2002Date of Patent: June 29, 2004Assignees: Renesas Technology Corporation, Hitachi Ulsi Systems Co., Ltd.Inventors: Hiroshi Kuroiwa, Yasuhiko Kokami
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Publication number: 20040100722Abstract: The present invention provides a magnetic disk storage system including a spindle motor that rotates a magnetic disk, a spindle motor drive circuit that rotatably drives the spindle motor, a magnetic head that performs reading of information on the magnetic disk, a voice coil motor that moves the magnetic head, and a voice coil motor drive circuit that drives the voice coil motor. When the magnetic head is loaded from a standby position to the surface of the magnetic disk, the rotational speed of the spindle motor is made slower than a rotational speed at a normal operation. Upon power-off, the spindle motor drive circuit is caused to carry out a stepup converter operation to thereby generate a voltage higher than a back electromotive voltage, and causes a control circuit and a drive circuit to operate by the high voltage to thereby enable speed control at the movement of the magnetic head to a predetermined standby position.Type: ApplicationFiled: October 24, 2003Publication date: May 27, 2004Applicants: Renesas Technology Corp., Hitachi ULSI Systems Co., Ltd.Inventor: Yasuhiko Kokami
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Publication number: 20040080293Abstract: In start-up control of a motor in which currents are caused to flow through any two of three phase coils to detect the polarity of a voltage induced in each de-energized phase, thereby determining the corresponding energized phase at start-up thereof, based on the polarity of the detected induced voltage, the levels of induced voltages are detected in addition to the polarity of the induced voltage for the de-energized phase to thereby determine the relationship between the magnitudes thereof, and the energized phase at the start-up is determined based on the relationship of magnitude between the polarity of each induced voltage and the level thereof.Type: ApplicationFiled: October 15, 2003Publication date: April 29, 2004Applicants: Renesas Technology Corp., Hitachi ULSI Systems Co., Ltd.Inventors: Minoru Kurosawa, Kunihiro Kawauchi, Yasuhiko Kokami
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Publication number: 20030227707Abstract: In a magnetic disk memory device, the shifting speed of the magnetic head in time of power supply interruption is detected, and a voice coil motor is controlled in accordance with the detected shifting speed to enable the head to be shunted safely and promptly.Type: ApplicationFiled: May 30, 2003Publication date: December 11, 2003Applicants: Hitachi, Ltd., Hitachi ULSI Systems Co., Ltd.Inventors: Yasuhiko Kokami, Minoru Kurosawa