| 序号 | 专利名 | 申请号 | 申请日 | 公开（公告）号 | 公开（公告）日 | 发明人 |
|---|---|---|---|---|---|---|
| 101 | SWITCHING PERIOD CONTROL OF MICROWAVE ASSISTED MAGNETIC RECORDING FOR POLE ERASURE SUPPRESSION | US16003413 | 2018-06-08 | US20180294010A1 | 2018-10-11 | SATOSHI TABATA; Atsushi Yamada; MICHIYA KAZUSAWA; Masato Shiimoto |
| A magnetic recording system for preventing data loss resulting magnetic oscillator current. The magnetic recording system includes a magnetic write head with a magnetic write pole, a magnetic oscillator near the magnetic write pole, and a write coil for magnetizing the write pole. Circuitry is connected with the magnetic write coil to supply a current to the write coil and connected with the magnetic oscillator to supply a current to the magnetic oscillator. The circuitry is configured to ensure that the current to the magnetic oscillator does not inadvertently magnetize the write pole after the magnetic write pole has demagnetized. | ||||||
| 102 | Switching period control of microwave assisted magnetic recording for pole erasure suppression | US15788173 | 2017-10-19 | US10020020B2 | 2018-07-10 | Satoshi Tabata; Atsushi Yamada; Michiya Kazusawa; Masato Shiimoto |
| A magnetic recording system for preventing data loss resulting magnetic oscillator current. The magnetic recording system includes a magnetic write head with a magnetic write pole, a magnetic oscillator near the magnetic write pole, and a write coil for magnetizing the write pole. Circuitry is connected with the magnetic write coil to supply a current to the write coil and connected with the magnetic oscillator to supply a current to the magnetic oscillator. The circuitry is configured to ensure that the current to the magnetic oscillator does not inadvertently magnetize the write pole after the magnetic write pole has demagnetized. | ||||||
| 103 | Switching period control of microwave assisted magnetic recording for pole erasure suppression | US14950938 | 2015-11-24 | US09799369B2 | 2017-10-24 | Satoshi Tabata; Atsushi Yamada; Michiya Kazusawa; Masato Shiimoto |
| A magnetic recording system for preventing data loss resulting magnetic oscillator current. The magnetic recording system includes a magnetic write head with a magnetic write pole, a magnetic oscillator near the magnetic write pole, and a write coil for magnetizing the write pole. Circuitry is connected with the magnetic write coil to supply a current to the write coil and connected with the magnetic oscillator to supply a current to the magnetic oscillator. The circuitry is configured to ensure that the current to the magnetic oscillator does not inadvertently magnetize the write pole after the magnetic write pole has demagnetized. | ||||||
| 104 | Implementing asymmetric degauss control for write head for hard disk drives | US14104143 | 2013-12-12 | US09280993B2 | 2016-03-08 | John Contreras; Zhen Jin; Yuanpeng Li; Xiaoyu Sui |
| A method, apparatus, and system for implementing enhanced asymmetric degauss control for a write head for hard disk drives. A degauss period is provided at the end of a write. The write head is driven asymmetrically with respect to the positive and negative driving currents during the degauss period. The average value of the write current during the degauss period is non-zero. | ||||||
| 105 | IMPLEMENTING ASYMMETRIC DEGAUSS CONTROL FOR WRITE HEAD FOR HARD DISK DRIVES | US14104143 | 2013-12-12 | US20150170687A1 | 2015-06-18 | John Contreras; Zhen Jin; Yuanpeng Li; Xiaoyu Sui |
| A method, apparatus, and system for implementing enhanced asymmetric degauss control for a write head for hard disk drives. A degauss period is provided at the end of a write. The write head is driven asymmetrically with respect to the positive and negative driving currents during the degauss period. The average value of the write current during the degauss period is non-zero. | ||||||
| 106 | Storage device having degauss circuitry with ramp generator for use in generating chirped degauss signal | US13556480 | 2012-07-24 | US08773817B2 | 2014-07-08 | Paul Mazur; Robert A. Norman; Jeffrey A. Gleason; Anamul Hoque |
| A hard disk drive or other disk-based storage device comprises a storage disk, a write head configured to write data to the disk, and control circuitry coupled to the write head. The control circuitry comprises a write driver and degauss circuitry associated with the write driver. The degauss circuitry is configured to generate a chirped degauss signal to be applied to the write head by the write driver. The degauss circuitry comprises a ramp generator configured to generate a ramp signal for controlling a frequency of at least a portion of a waveform of the chirped degauss signal. The ramp signal generated by the ramp generator may comprise a current ramp that is applied to a control input of a current controlled oscillator of the degauss circuitry. | ||||||
| 107 | Storage device having degauss circuitry with separate control of degauss signal steady state and overshoot portions | US13447741 | 2012-04-16 | US08705196B2 | 2014-04-22 | Boris Livshitz; Anamul Hoque; Jason S. Goldberg |
| A hard disk drive or other disk-based storage device comprises a storage disk, a write head configured to write data to the disk, and control circuitry coupled to the write head. The control circuitry comprises a write driver and degauss circuitry associated with the write driver. The degauss circuitry is configured to control a degauss signal waveform to be applied to the write head by the write driver, and comprises separate amplitude envelope control mechanisms for steady state and overshoot portions of the degauss signal waveform. The separate amplitude envelope control mechanisms may comprise, for example, separate steady state and overshoot controllers for controlling the amplitude envelope decay rates of the respective steady state and overshoot portions of the degauss signal waveform over the plurality of pulses. | ||||||
| 108 | METHOD AND CIRCUITRY FOR PROGRAMMABLY CONTROLLING DEGAUSS WRITE CURRENT DECAY IN HARD DISK DRIVES | US12939006 | 2010-11-03 | US20120105992A1 | 2012-05-03 | Marius Vicentiu Dina; Jeremy Robert Kuehlwein |
| A control circuit to provide a control current to control an amplitude of a write current in a magnetic media drive. The control circuit has an output circuit for providing the control current with an amplitude dependent on a bias voltage. A bias current path provides the bias voltage to the output circuit, and a current diverting circuit is connected to divert current from the bias current path. A programmable ramp voltage generator operates in response to a degauss enable signal, and a voltage-to-current converter receives the programmable ramp voltage to control the current diverting circuit to divert current from the bias current path at a rate determined by the programmable ramp voltage. The bias voltage and the write current decay according to the programmable ramp voltage. The write current decay can be made linear and independent of a beginning write current amplitude. | ||||||
| 109 | DEGAUSS CONTROL FOR MAGNETIC DISK-DRIVE PREAMPLIFIER | US12120525 | 2008-05-14 | US20090284860A1 | 2009-11-19 | TORU TAKEUCHI |
| One embodiment of the invention includes a preamplifier system for a magnetic disk-drive. The system includes a current distributor configured to generate a reference current and to decay the reference current from a first magnitude to a second magnitude during a degauss period to degauss a magnetic disk write head. The degauss period defines a transition from a write cycle to a read cycle of the magnetic disk-drive and has a predetermined time duration that is independent of the first magnitude of the reference current during the write cycle. An output driver is configured to provide a write current to the magnetic disk write head having a magnitude with an absolute value that is based on the reference current. | ||||||
| 110 | Channel postamble extension to de-gauss pole tips | US11436935 | 2006-05-18 | US07515371B1 | 2009-04-07 | Bruce Buch; Michael Mallary; Richard Olsen |
| A technique for de-gaussing the pole tips and yoke of a write transducer in a perpendicular magnetic recording system is provided. An oscillator in the read channel is configured to produce an adjustable signal pattern output to the preamplifier when a write operation ends for a given time and at a predetermined frequency, such that as the preamplifier write current decays, it decays with transitions (polarity reversals). This results in a decaying AC field being applied to the write transducer at the end of a media write operation, effectively de-gaussing it and reducing the effects of remanent magnetization remaining in the poles and yoke of the magnetic recording head after a write current is turned off. This defeats a potential pole tip lockup or yoke lockup circumstance in the magnetic recording media which can result in an inability to write further data or a possible erasure of valid data on the hard disk with which the write head is associated. | ||||||
| 111 | Thin laminated single pole perpendicular write head | US11435053 | 2006-05-16 | US07420780B2 | 2008-09-02 | Kochan Ju; Lijie Guan; Jeiwei Chang; Min Li; Ben Hu |
| Single write poles tend to large shape anisotropy which results in a very large remnant field when not actually writing. This has now been eliminated by giving the write pole the form of a three layer laminate in which two ferromagnetic layers are separated by a non-magnetic or antiferromagnetic coupling layer. Strong magnetostatic coupling between the outer layers causes their magnetization directions to automatically be antiparallel to one another, unless overcome by the more powerful write field, leaving the structure with a low net magnetic moment. The thickness of the middle layer must be carefully controlled. | ||||||
| 112 | Method for recording bursts on a disk and related apparatus | US11593494 | 2006-11-07 | US20070103807A1 | 2007-05-10 | Won-choul Yang |
| Embodiments of the invention provide a method for recording bursts on a disk and a related apparatus. In accordance with an embodiment of the invention, a method for recording bursts on a burst field of a servo sector of a disk comprises generating a first write current corresponding to burst data provided by a write channel circuit, and generating a second write current having a higher frequency than the first write current using a high frequency AC current generator, wherein the high frequency AC current generator is independent from the write channel circuit. The method further comprises selectively applying the first write current to a write head in response to a signal and selectively applying the second write current to the write head in response to the signal. | ||||||
| 113 | Write head demagnetizer | US10954599 | 2004-09-30 | US07106536B2 | 2006-09-12 | Hao Fang; Stephen Carl Kuehne |
| A demagnetizer for an inductive load having a driver circuit including at least one transistor and a ramp-down voltage source switchably connected to the driver circuit, so that when the ramp-down voltage source is connected to the transistor, it drives the voltage of the transistor below its threshold voltage. | ||||||
| 114 | Removing residual magnetization in a data transducer | US10797891 | 2004-03-09 | US07088537B2 | 2006-08-08 | Robert D. Cronch; James Brian Ray |
| Method and apparatus for removing residual magnetization in a data transducer, such as a recording head used to write data to a recording medium in a data storage device. A residual magnetization sense circuit senses a residual magnetization of a pole of the data transducer as a result of the application of a data transmission current to the transducer. A demagnetization current generator removes the residual magnetization by supplying the transducer with a demagnetizing current that decreases to a final magnitude in accordance with a selected profile. The demagnetization current preferably comprises a bi-directional, time varying current of selected frequency to the transducer that tapers linearly, exponentially or in a step-wise fashion to the final magnitude. The demagnetization profile is preferably continuously adapted during operation. Preferably, the sense circuit and demagnetization current generator are incorporated into a preamplifier/driver circuit which performs the demagnetization operation in a self-contained fashion. | ||||||
| 115 | Method and apparatus for degaussing write head in a disk drive | US11087637 | 2005-03-24 | US20050243457A1 | 2005-11-03 | Manabu Akamatsu; Kazuhito Shimomura; Yuji Sakai |
| A disk drive which includes a head amplifier having a function of degaussing a magnetic head effective to suppression of an EAW phenomenon is disclosed. The head amplifier includes a degaussing controller which performs switching from write operation to degaussing operation, a write driver which outputs degaussing current necessary for the degaussing operation, and a current control unit which sets a current waveform of the degaussing current. | ||||||
| 116 | Removing residual magnetization in a data transducer | US10797891 | 2004-03-09 | US20050200997A1 | 2005-09-15 | Robert Cronch; James Ray |
| Method and apparatus for removing residual magnetization in a data transducer, such as a recording head used to write data to a recording medium in a data storage device. A residual magnetization sense circuit senses a residual magnetization of a pole of the data transducer as a result of the application of a data transmission current to the transducer. A demagnetization current generator removes the residual magnetization by supplying the transducer with a demagnetizing current that decreases to a final magnitude in accordance with a selected profile. The demagnetization current preferably comprises a bi-directional, time varying current of selected frequency to the transducer that tapers linearly, exponentially or in a step-wise fashion to the final magnitude. The demagnetization profile is preferably continuously adapted during operation. Preferably, the sense circuit and demagnetization current generator are incorporated into a preamplifier/driver circuit which performs the demagnetization operation in a self-contained fashion. | ||||||
| 117 | Multiple magnetoresistive (MR) layer sensor element having longitudinal bias layers with non-parallel magnetizations | US09920602 | 2001-08-02 | US06754048B2 | 2004-06-22 | Min Li; Simon H. Liao |
| Within a method for forming a magnetoresistive (MR) sensor element there is first provided a substrate. There is then formed over the substrate a first magnetoresistive (MR) layer having formed contacting the first magnetoresistive (MR) layer a magnetically biased first magnetic bias layer biased in a first magnetic bias direction with a first magnetic bias field strength. There is also formed separated from the first magnetoresistive (MR) layer by a spacer layer a second magnetoresistive (MR) layer having formed contacting the second magnetoresistive (MR) layer a magnetically un-biased second magnetic bias layer. There is then biased through use of a first thermal annealing method employing a first thermal annealing temperature, a first thermal annealing exposure time and a first extrinsic magnetic bias field the magnetically un-biased second magnetic bias layer to form a magnetically biased second magnetic bias layer having a second magnetic bias field strength in a second magnetic bias direction non-parallel to the first magnetic bias direction while simultaneously partially demagnetizing the magnetically biased first magnetic bias layer to provide a partially demagnetized magnetically biased first magnetic bias layer having a partially demagnetized first magnetic bias field strength less than the first magnetic bias field strength. Finally, there is then annealed thermally through use of a second thermal annealing employing a second thermal annealing temperature and a second thermal annealing exposure time without a second magnetic bias field: (1) the partially demagnetized magnetically biased first magnetic bias layer layer to form a remagnetized partially demagnetized first magnetic bias layer having a remagnetized partially demagnetized first netic bias field strength greater than the partially demagnetized first magnetic bias field strength; and (2) the magnetically biased second magnetic bias layer to form a further magnetically biased second magnetic bias layer having a further magnetized second magnetic bias field strength greater than the second magnetic bias field strength. | ||||||
| 118 | Flux closed single pole perpendicular head for ultra narrow track | US10273603 | 2002-10-17 | US20040075927A1 | 2004-04-22 | Hardayal Singh Gill |
| A single pole perpendicular write head is provided comprising an inductive write head pole structure comprising a layered structure alternating a plurality of ferromagnetic layers with a plurality of antiparallel coupling layers to form an antiparallel coupled ferromagnetic stack. The antiparallel coupling of the ferromagnetic layers when the head is not writing forms a flux closed magnetic configuration of the write pole resulting in reduction or elimination of stray remanence fields at the pole tip region that may cause unwanted data erasure at the disk surface. | ||||||
| 119 | Magnetic field sensor with perpendicular axis sensitivity, comprising a giant magnetoresistance material or a spin tunnel junction | US09373430 | 1999-08-13 | US06577124B2 | 2003-06-10 | Reinder Coehoorn; Kars-Michiel H. Lenssen; Pascal J. H. Bloemen |
| A thin film magnetic field sensor with perpendicular axis sensitivity uses either a giant magnetoresistance material element or a spin tunnel junction element. The sensor element has ferromagnetic layers which have strongly different uniaxial anisotropies and/or a modified magnetization curve, achieved by antiferromagnetic exchange coupling with an auxiliary ferromagnetic layer. A strongly miniaturizable sensor has four spin tunnel junction elements connected to form a Wheatstone bridge. The magnetically sensitive element functions equally as well as a laminated flux concentrator, resulting in a low noise single domain configuration. The very simple design also allows easy definition of the fixed magnetization direction of a counter electrode. Very high output voltage combined with very low power is achieved. | ||||||
| 120 | System and method providing programmable GMR head pin layer reset in conjunction with high density drive read/write preamplifiers | US09794508 | 2001-02-26 | US20020118475A1 | 2002-08-29 | David Ng; Yuji Isobe |
| A system and methodology is provided for resetting a pin layer within a GMR/Spin-Valve head. The system includes a preamplifier to at least one of read, write, and bias a GMR head having a pin layer. A pin layer reset circuit generates a programmable signal to reset the pin layer, wherein the programmable signal is adjustable according to at least one of a signal magnitude, signal polarity, signal pulse duration, and signal duty cycle. The programmable signal can include a voltage and and/or current. | ||||||
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