Optimization of thermal fly-height control slider geometry for Tbit/in2 recording

2010 ◽  
Vol 16 (6) ◽  
pp. 1021-1034 ◽  
Author(s):  
Antonis I. Vakis ◽  
Andreas A. Polycarpou
Keyword(s):  
Height Control ◽  
Fly Height

Performance Optimization of Thermal Nano-Actuator for Fly Height Control in Disk Drives

2009 ◽  
Author(s):  
Haisan Tan ◽  
Bo Liu ◽  
Mingsheng Zhang ◽  
Shengkai Yu
Keyword(s):  
Performance Optimization ◽  
Power Input ◽  
Vertical Position ◽  
Disk Drives ◽  
Height Control ◽  
Line Spacing ◽  
Simulation Results ◽  
Heater Design ◽  
Fly Height ◽  
Actuator Design

Slider with thermal fly height control (TFC) uses a thermal heater to produce localized thermal protrusion and adjust the vertical position of the read/write head. This paper reports authors’ efforts in exploring large protrusion stroke with minimal heater power input whilst preserving heater robustness in the TFC slider, with an optimized thermal nano-actuator design. Effects of both heater line width and line spacing on TFC slider performances are investigated. A novel ‘Stream-River’ heater design approach is proposed. Simulation results conclude that the “Stream-River” approach is of both high power-protrusion efficiency and high heater robustness.

Ranking of Thermal Asperity (TA) Interaction During Seeking Under Various Fly-Height Conditions

2020 ◽  
Author(s):  
Abhishek Srivastava ◽  
Bernd Lamberts ◽  
Ning Li ◽  
Bernhard Knigge
Keyword(s):  
Theoretical Analysis ◽  
State Interaction ◽  
Idle State ◽  
Height Control ◽  
Interaction Mechanisms ◽  
Industry Standard ◽  
Maximum Benefit ◽  
Protection Mechanisms ◽  
Fly Height ◽  
Experimental Corroboration

Abstract HDD heads have various interaction mechanisms with thermal asperities (TAs), and protection mechanisms need to be put in place to ensure the head-disk interaction (HDI) resulting from them is eliminated or minimized to the highest extent possible. It is straightforward to not allow the head sit-on-track on cylinders that have such TAs on them, and the same principle can be extended to so-called high TAs (HTAs), whose height is more than the fly height of the head, so heads do not inadvertently interact with the TA even when motion is triggered on another head, since the entire head stack moves together. Similar TA interactions also occur when the head seeks across the tracks. Typical short seeks have thermal fly-height control (TFC) turned on while it is turned on during long seeks, which is greater than a few hundred tracks. Heads can also interact with TAs during retract and arrival of the head during such long seeks. Finally, background media scan (BGMS), which is an industry standard, when the drive enters an idle state. Interaction with HTAs can also occur when the drive enters such a state. Typical seek avoidance attempts to eliminate TA interaction during seeking, however it is not straightforward to determine which of the seek mechanism: TFC On during short seeks, retract/arrival during long seeks, HTA interaction during long seeks with TFC off, or idle TA interaction causes the greatest HDI. Through theoretical analysis and experimental corroboration, this paper intends to rank the various modes of TA interaction, so by developing features for eliminating or minimizing them in that order could help bring the maximum benefit for achieving minimum lifetime reduction of the head due to such interaction.

A Method to Reduce Head-Disk Interface (HDI) Degradation Risk During Thermal Asperity (TA) Mapping in a Hard Disk Drive

2020 ◽  
Author(s):  
Abhishek Srivastava ◽  
Rahul Rai ◽  
Karthik Venkatesh ◽  
Bernhard Knigge
Keyword(s):  
Hard Disk Drive ◽  
Bias Voltage ◽  
Disk Drive ◽  
Test Time ◽  
Head Disk Interface ◽  
Disk Interface ◽  
Height Control ◽  
Contact Sensor ◽  
Fly Height ◽  
Sample Set

Abstract One of the issues in thermal asperity (TA) detection using an embedded contact sensor (ECS) is the degradation caused to the read/write elements of the head while interacting with the TA. We propose a method to reduce such head-disk interaction (HDI) during TA detection and classification by flying higher at low thermal fly-height control (TFC) power, which minimizes the interaction of the TA with the head. The key idea is to scan the head at higher fly height, but with higher ECS bias voltage. Initial experiments have shown that the TA count follows a negative cubic relationship with the backoff at various bias levels, and that it follows a square relationship with bias at various backoff levels. Using a sample set, the calibration curves i.e. the golden relationship between these parameters can be established. Using these, one can start the TA detection at the highest backoff and high ECS bias, and start to estimate the nominal TA count. By mapping out these TAs and ensuring the head does not fly over them again to prevent HDI, the fly height can then be lowered, and the rest of the TA cluster can be scanned. Following this method iteratively, the entire TA cluster can be mapped out with minimal interaction with the head. Although this method entails an increase in the test time to detect and map all TAs, compared to detecting them with TFC being on, this can help improve the reliability of the drive by protecting the sensitive read/write elements especially for energy assisted recording from HDI.

Slider-Disk Contact Characterization Using a Thermal Fly-Height Control Slider

2009 ◽  
Vol 45 (11) ◽  
pp. 5026-5029 ◽  
Author(s):  
Lionel Ng ◽  
Mingsheng Zhang ◽  
Bo Liu ◽  
Yansheng Ma
Keyword(s):  
Height Control ◽  
Disk Contact ◽  
Fly Height

scholarly journals Parametric Investigations at the Head-Disk Interface of Thermal Fly-Height Control Sliders in Contact

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
Sripathi V. Canchi ◽  
David B. Bogy ◽  
Run-Han Wang ◽  
Aravind N. Murthy
Keyword(s):  
Hard Disk Drives ◽  
Air Bearing ◽  
Head Disk Interface ◽  
Bearing Surface ◽  
Surface Design ◽  
Disk Interface ◽  
Height Control ◽  
Experimental Findings ◽  
And Control ◽  
Fly Height

Accurate touchdown power detection is a prerequisite for read-write head-to-disk spacing calibration and control in current hard disk drives, which use the thermal fly-height control slider technology. The slider air bearing surface and head gimbal assembly design have a significant influence on the touchdown behavior, and this paper reports experimental findings to help understand the touchdown process. The dominant modes/frequencies of excitation at touchdown can be significantly different leading to very different touchdown signatures. The pressure under the slider at touchdown and hence the thermal fly-height control efficiency as well as the propensity for lubricant pickup show correlation with touchdown behavior which may be used as metrics for designing sliders with good touchdown behavior. Experiments are devised to measure friction at the head-disk interface of a thermal fly-height control slider actuated into contact. Parametric investigations on the effect of disk roughness, disk lubricant parameters, and air bearing surface design on the friction at the head-disk interface and slider burnishing/wear are conducted and reported.

Overview of Fly Height Control Applications in Perpendicular Magnetic Recording

2007 ◽  
Vol 43 (2) ◽  
pp. 709-714 ◽  
Author(s):  
Yawshing Tang ◽  
Soo-Youl Hong ◽  
Na-Young Kim ◽  
Xiaodong Che
Keyword(s):  
Magnetic Recording ◽  
Control Applications ◽  
Height Control ◽  
Perpendicular Magnetic Recording ◽  
Fly Height

1110 Investigation of Fly-height Change Efficiency on Thermal Fly-height Control Slider

2008 ◽  
Vol 2008 (0) ◽  
pp. 34-37
Author(s):  
Satoru OOKUBO ◽  
Toshiya SHIRAMATSU ◽  
Kiyoshi HASHIMOTO ◽  
Masayuki KURITA ◽  
Hidekazu KOHIRA
Keyword(s):  
Height Control ◽  
Height Change ◽  
Fly Height

Three-DOF dynamic model with lubricant contact for thermal fly-height control nanotechnology

2012 ◽  
Vol 45 (13) ◽  
pp. 135402 ◽  
Author(s):  
Antonis I Vakis ◽  
Christoforos N Hadjicostis ◽  
Andreas A Polycarpou
Keyword(s):  
Dynamic Model ◽  
Height Control ◽  
Fly Height

Thermal Fly-Height Control Slider Instability and Dynamics at Touchdown: Explanations Using Nonlinear Systems Theory

2011 ◽  
Vol 133 (2) ◽  
Author(s):  
Sripathi Vangipuram Canchi ◽  
David B. Bogy
Keyword(s):  
Nonlinear Systems ◽  
Systems Theory ◽  
Resonance Condition ◽  
Hard Disk Drives ◽  
Jump Condition ◽  
Surface Design ◽  
Disk Interface ◽  
Height Control ◽  
Low Head ◽  
Fly Height

Thermal fly-height control sliders are widely used in current hard disk drives to control and maintain subnanometer level clearance between the read-write head and the disk. The peculiar dynamics observed during touchdown/contact tests for certain slider designs is investigated through experiments and analytical modeling. Nonlinear systems theory is used to highlight slider instabilities arising from an unfavorable coupling of system vibration modes through an internal resonance condition, as well as the favorable suppression of instabilities through a jump condition. Excitation frequencies that may lead to large amplitude slider vibrations and the dominant frequencies at which slider response occurs are also predicted from theory. Using parameters representative of the slider used in experiments, the theoretically predicted frequencies are shown to be in excellent agreement with experimental results. This analytical study highlights some important air bearing surface design considerations that can help prevent slider instability as well as help mitigate unwanted slider vibrations, thereby ensuring the reliability of the head-disk interface at extremely low head-disk clearances.

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