公开(公告)号：US10832704B2

公开(公告)日：2020-11-10

申请号：US16716836

申请日：2019-12-17

Applicant: Seagate Technology LLC

Inventor： Drew Michael Mader

IPC: G11B11/105 ,  G11B5/012 ,  G11B13/04 ,  G11B5/00 ,  G11B7/1267 ,  G11B7/1263 ,  G11B7/126

Abstract: A method includes generating, during manufacture of a heat-assisted magnetic recording (HAMR) disk drive, a temperature compensation equation for a compensation factor using initial operating currents supplied to a laser diode of the disk drive at different initial operating temperatures and an efficiency value based on the initial operating temperatures. The operating currents are representative of currents for recording data to or erasing data from a magnetic recording medium. The temperature compensation equation is stored in the disk drive. A subsequent efficiency value is determined based on at least one of the initial operating temperatures and an operating temperature differing from the initial operating temperatures. An updated compensation factor at the operating temperature is determined during field operation using the temperature compensation equation and the subsequent efficiency value. An updated operating current is calculated using the updated compensation factor and the operating temperature. A current supplied to the laser diode for a subsequent write operation is adjusted to the updated operating current.

公开(公告)号：US10770106B1

公开(公告)日：2020-09-08

申请号：US16724569

申请日：2019-12-23

Applicant: Seagate Technology LLC

Inventor： Drew Michael Mader ,  Tim Rausch ,  Josh Ward Christensen

IPC: G11B5/02 ,  G11B7/126 ,  G11B5/40 ,  G11B5/012 ,  G11B5/455 ,  G11B11/105 ,  G11B11/00 ,  G11B5/60 ,  G11B20/18 ,  G11B7/1387 ,  G11B7/1263 ,  G11B7/1267 ,  G11B5/00

Abstract: A heat-assisted recording head is moved onto a ramp such that the recording head is thermally isolated from a moving disk. A heating device is activated on the recording head to cause the recording head to obtain a high temperature that is not obtainable when proximate to the moving disk. The recording head is moved over the moving disk such that the recording head reaches an operating temperature that is below the high temperature. One or more temperatures between the high temperature and the operational temperature are determined at which a laser of the recording head experiences mode-hopping. The one or more temperatures are stored and accessed by a controller to mitigate mode hopes during an operation of the recording head.

公开(公告)号：US09349415B1

公开(公告)日：2016-05-24

申请号：US14716171

申请日：2015-05-19

Applicant: Seagate Technology LLC

Inventor： Drew Michael Mader ,  Alfredo Sam Chu ,  Tim Rausch

IPC: G11B27/36

CPC classification number: G11B27/36 ,  G11B5/012 ,  G11B5/59627 ,  G11B2005/0021

Abstract: A signal is recorded over at least part of a track a heat-assisted recording medium via a heat-assisted magnetic recording head. Symmetry of a cross-track profile of the recorded signal is determined, and the recording head is qualified based on the symmetry of the cross-track profile.

Abstract translation: 通过热辅助磁记录头将信号记录在至少部分轨道上的热辅助记录介质上。 确定记录信号的交叉轨道轮廓的对称性，并且基于交叉轨道轮廓的对称性对记录头进行鉴定。

公开(公告)号：US11908502B2

公开(公告)日：2024-02-20

申请号：US17694442

申请日：2022-03-14

Applicant: Seagate Technology LLC

Inventor： Walter R. Eppler ,  Drew Michael Mader

IPC: G11C16/10 ,  G11C11/16 ,  H03M1/06

CPC classification number: G11C11/1673 ,  G11C11/1675 ,  G11C11/1677 ,  G11C11/1693 ,  H03M1/0636

Abstract: A method for reducing noise in a read signal due attributable to read element asymmetry provides for transmitting a write signal through a write precompensation circuit that shifts rising edges and falling edges of each of pulse in the write signal by a select magnitude and in opposite directions. After the write signal is encoded on a media, a corresponding read signal is read, with a read element, from the media. The method further provides for transmitting the read signal through a magnetoresistive asymmetry compensation (MRAC) block that is tuned to correct second-order non-linearities characterized by a particular set of distortion signatures. The select magnitude of the waveform shift applied by the write precompensation circuit introduces a non-linear signal characteristic that combines with non-linear signal characteristics introduced by the read element to generate one of the particular distortion signatures that is correctable by the MRAC block.

公开(公告)号：US09916849B1

公开(公告)日：2018-03-13

申请号：US15347129

申请日：2016-11-09

Applicant: Seagate Technology LLC

Inventor： Drew Michael Mader ,  Tim Rausch ,  James E. Angelo

IPC: G11B11/00 ,  G11B7/1263 ,  G11B7/126 ,  G11B5/00 ,  G11B5/60 ,  G11B11/105 ,  G11B7/1267

CPC classification number: G11B7/126 ,  G11B5/012 ,  G11B5/6088 ,  G11B7/1267 ,  G11B11/10506 ,  G11B11/1051 ,  G11B2005/0021

Abstract: An optical power level applied via a laser when recording data to a track of a heat-assisted recording medium is determined. In response to the optical power level being too low or too high, remedial action is taken to prevent loss of data on one or more of the track and an adjacent track.

公开(公告)号：US11011189B2

公开(公告)日：2021-05-18

申请号：US16854377

申请日：2020-04-21

Applicant: Seagate Technology LLC

Inventor： Drew Michael Mader ,  Wenzhong Zhu

IPC: G11B5/09 ,  G11B5/00

Abstract: A read channel is configured to obtain an analog readback waveform from a magnetic recording medium of a disk drive at a sampling rate of one sample per one written bit. A buffer is coupled the read channel. Circuitry is configured to inject a plurality of different phase offsets into the read channel for each of a plurality of revolutions of the medium. The circuitry is also configured to store, in a buffer, an amplitude of the readback waveform for each of the different phase offsets. The circuitry is further configured to generate an oversampled readback waveform using the amplitudes stored in the buffer.

公开(公告)号：US20200251132A1

公开(公告)日：2020-08-06

申请号：US16854377

申请日：2020-04-21

Applicant: Seagate Technology LLC

Inventor： Drew Michael Mader ,  Wenzhong Zhu

IPC: G11B5/09

Abstract: A read channel is configured to obtain an analog readback waveform from a magnetic recording medium of a disk drive at a sampling rate of one sample per one written bit. A buffer is coupled the read channel. Circuitry is configured to inject a plurality of different phase offsets into the read channel for each of a plurality of revolutions of the medium. The circuitry is also configured to store, in a buffer, an amplitude of the readback waveform for each of the different phase offsets. The circuitry is further configured to generate an oversampled readback waveform using the amplitudes stored in the buffer.

公开(公告)号：US20200126586A1

公开(公告)日：2020-04-23

申请号：US16716836

申请日：2019-12-17

Applicant: Seagate Technology LLC

Inventor： Drew Michael Mader

IPC: G11B5/012 ,  G11B13/04

Abstract: A method includes generating, during manufacture of a heat-assisted magnetic recording (HAMR) disk drive, a temperature compensation equation for a compensation factor using initial operating currents supplied to a laser diode of the disk drive at different initial operating temperatures and an efficiency value based on the initial operating temperatures. The operating currents are representative of currents for recording data to or erasing data from a magnetic recording medium. The temperature compensation equation is stored in the disk drive. A subsequent efficiency value is determined based on at least one of the initial operating temperatures and an operating temperature differing from the initial operating temperatures. An updated compensation factor at the operating temperature is determined during field operation using the temperature compensation equation and the subsequent efficiency value. An updated operating current is calculated using the updated compensation factor and the operating temperature. A current supplied to the laser diode for a subsequent write operation is adjusted to the updated operating current.

公开(公告)号：US10339963B1

公开(公告)日：2019-07-02

申请号：US16025424

申请日：2018-07-02

Applicant: Seagate Technology LLC

Inventor： Drew Michael Mader ,  Ian James Gilbert ,  Walter R. Eppler ,  Tim Rausch

IPC: G11B11/00 ,  G11B5/09 ,  G11B5/00 ,  G11B5/60 ,  G11B7/1263 ,  G11B7/1267 ,  G11B7/126

Abstract: Pseudorandom bit sequences are recorded to a heat-assisted recording medium at a laser power that is stepped while recording the pseudorandom bit sequences. The pseudorandom bit sequences are read from the heat-assisted recording medium to determine timing differences between bits written before and after the laser power is stepped. A thermal gradient of bits written to the heat-assisted recording medium is determined based on the timing differences.

公开(公告)号：US09202506B1

公开(公告)日：2015-12-01

申请号：US14595740

申请日：2015-01-13

Applicant: Seagate Technology LLC

Inventor： Drew Michael Mader ,  Alfredo Sam Chu ,  Jason Riddering

IPC: G11B7/1263 ,  G11B5/31 ,  G11B5/48 ,  G11B5/60 ,  G11B5/00

CPC classification number: G11B7/1263 ,  G11B5/3133 ,  G11B5/314 ,  G11B5/4866 ,  G11B5/6088 ,  G11B2005/0021

Abstract: A power level is applied to a laser that heats a heat-assisted recording medium is increased during recording for a plurality of iterations. Each iteration involves writing test data to a plurality of sequential tracks of the recording medium using the power level and determining bit error rates of the test data. Based on the bit error rates of the iterations, a power boost profile is determined. The power boost profile starts at a baseline level at a first track of a plurality of sequentially-written tracks, incrementally increases to a steady-state level over a first portion of the tracks, and remains at the steady-state level over subsequent ones of the tracks. The power boost profile is applied to the laser when recording to the recording medium.

Abstract translation: 对于在多次迭代的记录期间加热热辅助记录介质的激光器施加功率电平。 每次迭代涉及使用功率电平将测试数据写入记录介质的多个顺序轨道并确定测试数据的误码率。 基于迭代的误码率，确定功率提升曲线。 功率提升曲线在多个顺序写入的轨道的第一轨道处的基线水平处开始，在轨道的第一部分上递增地增加到稳态水平，并且在随后的轨迹中保持在稳态水平 轨道。 当记录到记录介质时，功率提升曲线被应用于激光器。