Accurate measurement and evaluation of dynamic characteristics of flying head slider for large-capacity fast-access magnetic disk storage

Ohkubo, T.; Hayashi, Toshiyuki; Mitsuya, Yasunaga

doi:10.1109/tmag.1987.1065453

Cited by 8 publications

(7 citation statements)

References 3 publications

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“…[7], measurement by Laser Doppler Vibrometer LDV) 8] [9][lO],and capacitance-type measurement 1l][12\r13] are frequently used. Of these methods, AE detection is the most suitable for measuring head slider contact with the disk media as well as head and me-dia motion of an actual magnetic storage device.…”

Section: Contact Detection Organization Contact Detection Methodsmentioning

confidence: 99%

Projection Evaluation Method of Perpendicular Magnetic Disk Media Using Small Piezoelectric Transducer

Mochizuki

Hayashi

Sato³

1989

J. Magn. Soc. Jpn.

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This report describes a technique for detecting head disk media contact in order to evaluate perpendicular magnetic disk media. The detector uses a small piezoelectric transducer(PZT) , attached to the flying head slider, called PZT-Contact Detection Sensor(PCS). It is most useful for evaluating microscopic projections and dust particles adhering to the perpendicular magnetic disk medium surface which could result in head crash. Experimental results and analyses of AE signals derived from the PCS were detailed. To improve the SNR of an AE signal from the PCS, a new frequency converter circuit with a mixer and a new type of PZT , called D-PZT , was developed. Additionally the mechanism of AE signal production from the PCS when head comes in contact with or passes over a projection on the media surface was also clarified.

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Section: Contact Detection Organization Contact Detection Methodsmentioning

confidence: 99%

Projection Evaluation Method of Perpendicular Magnetic Disk Media Using Small Piezoelectric Transducer

Mochizuki

Hayashi

Sato³

1989

J. Magn. Soc. Jpn.

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“…The modified Reynolds equation based on the velocity boundary conditions of first order slip flow (Burgdorfer, 1959) or second order slip flow (Hsia and Domoto, 1983) for a small Knudsen number: Kn< 1, has been widely used as a lubrication equation. The numerical solution of the equations in the frequency domain (Ono, 1975) and in the time domain (Tang, 1971;Castelli and Stevenson, 1968;White and Nigam, 1980) have been established, and the validity of the dynamic analysis for conventional flying head sliders has been reported by comparing the numerical results with experimental measurements Ohkubo et al, 1987;Tanaka et al, 1989).…”

Section: Introductionmentioning

confidence: 99%

Dynamic Characteristics of Gas-Lubricated Slider Bearings Under High Knudsen Number Conditions

Hayashi

Fukui

Ohkubo

et al. 1990

Journal of Tribology

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This paper presents numerical analyses of the dynamic characteristics of gas-lubricated slider bearings under high Knudsen number conditions using a generalized lubrication equation based on the the Boltzmann equation. These analyses are compared with those of the slip flow approximation equations and the differences are clarified. The present analysis is applied to the dynamic response of flying head sliders for magnetic disk storage devices. For a small slider with ultra-thin spacing, the deviations of the slip flow approximation equations are remarkable in regard to steady flying characteristics, but insignificant in regard to dynamic characteristics.

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“…The Laser Doppler Vibrometer (LDV) [36,37,38], which can be used to measure the motion velocity of objects, is another optical method for evaluating the dynamic characteristics of the slider. Using LDV, Miu and Bogy measured transient motion in the Against this background, Ohkubo and Kishigami [39,40] presented an accurate spacing measurement technique which focuses a visible laser into a minute cavity on the slider and disk interface, and electrically detects the interference intensity change, which corresponds to the spacing variation. In this section several methods to measure flying height will be briefly reviewed.…”

Section: Literature Reviewmentioning

confidence: 99%

“…3) node (39), (40) and (41) are the elements to form the step of cantilever, 4) the input port is the PZT elements, including nodes from (19) From the above study, the mechanical impedance could be retrieved by the input electrical impedance as Equation if the transduction matrix has been identified. In the next section, we will carry out the measurement of mechanical impedance at the centre of the step node (40) of cantilever by this four-pole model.…”

Section: Chaptermentioning

confidence: 99%

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Finite element modeling and simulation of hard disk slider with in-situ flying height measurement capability

He¹

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To achieve areal density of 1 Tb/in" in the next generation hard disk drive (HDD), the slider has to fly at a height of 3-4 nanometers above the disk surface. To obtain the required accuracy of track seeking and following, the same slider may have to possess capability of in-situ flying height (FH) measurement. A new slider has been proposed and designed with in-situ measurement capability of flying height and mechanical impedance of air bearing. With proper aerodynamic design, the slider will fly at the prescribed height. Onto this slider, a much more flexible cantilever will be built to carry the read/write head at its tip. The flexible cantilever, which is driven by PZT film coated on its surfaces, is capable of measuring the flying height in real time. The output of the PZT, namely the electrical impedance, is used as a signal to sense the flying height. Mechanically, this system has three coupling fields, which are related to electrical (PZT), structure (cantilever) and fluid (air bearing). In this PhD study, the air bearing is modeled as by Fukui model due to its accuracy for describing the air bearing in large Knudsen number. Finite element (FE) method was applied to study the cantilever, PZT film and air bearing by building a FE model for them. With the well established FE procedure, the in-situ flying height measurement capability of the new slider has been validated by virtual testing or numerical simulation. The numerical results show that there is a good linearity between the flying height and the output i ATTENTION: The Singapore Copyright Act applies to the use of this document. Nanyang Technological University Library The author wishes to extend his greatest gratitude and appreciation to the following persons, who offered invaluable contribution towards my PhD study: Professor Ling Shih-Fu, the project supervisor, for his distinguished guidance, respectable patience, and novel idea on the project, further more, for his excellent effort on scientific research and distinguished discovery on the novel method on dynamic systems. From him, I learnt much more about the research and life. Dr. Liu Bo, the project co-supervisor, for his respectable guidance, effective discussion and creative advice. Moreover, he gives me lots of advices on research, work and life. The love and the support of my family are instrumental in my ability to complete this report. To them this report is gratefully dedicated. Dr. Zhang Mingsheng, who gives me lots of advices on the MEMS fabrication and slider design. Thanks are also given to associate professor Qiu Jinhao, for his respectable guidance and help on the project. m

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Accurate measurement and evaluation of dynamic characteristics of flying head slider for large-capacity fast-access magnetic disk storage

Cited by 8 publications

References 3 publications

Projection Evaluation Method of Perpendicular Magnetic Disk Media Using Small Piezoelectric Transducer

Projection Evaluation Method of Perpendicular Magnetic Disk Media Using Small Piezoelectric Transducer

Dynamic Characteristics of Gas-Lubricated Slider Bearings Under High Knudsen Number Conditions

Finite element modeling and simulation of hard disk slider with in-situ flying height measurement capability

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