Overview of Fly Height Control Applications in Perpendicular Magnetic Recording

This paper presents an investigation of the light contact in a head disk interface with dynamic flying height control. The touchdown test is conducted for a dynamic flying height control slider and the response is recorded using AE sensor. The bouncing instability and light contacts are observed during thermal actuated touching down process of the slider. The physics-based simulation is conducted to correlate with the experiments, so as to characterize bouncing instability and the factors affecting bouncing instability. The enhanced spectrogram and HHT approaches are used to extract and characterize the non-stationary characteristics of the weak signal of slider response under light contact. It is found that the light contacts are constituted by a series of intermittent transient impact responses with frequency identical to slider's pitch mode.

Section: Experimental Setup and Resultssupporting

confidence: 91%

Characterization of light contact in head disk interface with dynamic flying height control

Sheng

2011

“…This low level remains steady when the driving voltage was further increased. During the process of the increase of the driving voltage, the output AE signal exhibit three distinct regions: A (without driving voltage), B (with threshold driving voltage) and C (with saturated driving voltage), which were previously reported (Tang et al 2007;Zhang et al 2009;Xu et al 2009;Hua et al 2009;Canchi and Bogy 2010).…”

Section: Experimental Results and Parameter Estimationsupporting

confidence: 62%

“…Slider dynamics in the regime from sub-10 nm clearance to sub-nanometer clearance has been widely investigated by many researchers (Juang et al 2006;Li et al 2009;Zhang et al 2009;Liu et al 2009;Knigge et al 2006;Tang et al 2007;Xu et al 2009;Hua et al 2009;Canchi and Bogy 2010;Suh and Polycarpou 2005;Vakis et al 2009;Tani et al 2009;Ono 2009; Thornton and Bogy 2004). There are many experimental and numerical investigations as well as qualitative correlations.…”

Section: Introductionmentioning

confidence: 99%

A parameter identification method for thermal flying-height control sliders

Sheng

2011

This paper employs higher order frequency response functions to describe the closed-form solution of nonlinear dynamics of MEMS thermal actuated flyingheight control (TFC) slider, and employs the measured acoustic emission signal of a TFC slider during touch down as its vibration approximation to correlate with the derived closed-form solution for parameter identification. It is shown that during slider touchdown when heater power is increased gradually, the slider performs weak nonlinear vibrations in early transition phase, and exhibits linear vibration in the following steady sliding phase. These results are useful for the clarification of complicated dynamics and the designs of active sliders in sub-nanometer clearance regime.

“…A stable low flying height is necessary to achieve low bit error rates (Tang et al 2007). Thermal flying height control is accomplished through a resistance heater element in close proximity to the read write element.…”

Section: Introductionmentioning

confidence: 99%

Servo signal processing for flying height control in hard disk drives

Boettcher

Lacey²,

Li³

et al. 2011

A novel method of measuring the relative headmedium spacing based on a measurement in the servo sectors is developed and simulated using a read back signal model. The spacing measurement is tested experimentally on a spin stand where the flying height is varied using the resistance heater element in a thermal flying height control slider. In addition, voltage step response measurements were obtained. The data were used to perform system identification and estimate the dynamics of the thermal actuator. The model can potentially be used for thermal flying height control.