Recording Disks Research Articles

20pm3-PM009 液体ナノ薄膜の流動特性の加熱による影響

In the head-disk interface (HDI) of a hard disk drive (HDD), the effects of lubricant deformation on the flying characteristics of a head slider increase as the flying height decreases. Therefore, it is very important to investigate the deformation and flow characteristics of lubricant on a recording disk. In particular, in heat-assisted magnetic recording (HAMR), laser heating of the lubricant induces surface tension distribution and evaporation of lubricant, which may cause deformation of the lubricant film. In this paper, flow characteristics of liquid nano-film of perfluoropolyether (PFPE) on solid substrate is investigated experimentally. Using the modified Boltzmann-Matano method, diffusion coefficients of liquid nano-step, which shows the flow characteristics, are calculated. As a result, effects of initial film thickness and temperature on the flow characteristics were clarified.

Polarization dependent diffraction from anisotropic Ag nanorods grown on DVD grating templates by oblique angle deposition

In this work, we demonstrate surface plasmon (SP) excitations by white light irradiation on Ag nanorod covered diffraction grating substrates. Recordable digital versatile discs (DVD) were used as the diffraction grating substrates on which aligned Ag nanorods arrays were deposited by oblique angle deposition. A simple experimental method based on normal incidence optical transmission was used to monitor the first order diffraction spectra from these Ag nanorod arrays on DVD gratings. The SP peak positions were observed to have dependence on polarization of the incident light and get shifted according to the aspect ratio of nanorods. The results illustrate that the radiative properties of Ag nanorod arrays on the DVD grating can be tailored just by controlling the geometric dimensions of the Ag nanorods. These Ag nanorod arrays on DVD grating templates may be used for cost efficient and sensitive surface plasmon based applications such as refractive index measurement and biosensing.

Investigation of Lubricant Transfer between Slider and Disk Using Molecular Dynamics Simulation

A model for lubricant transfer from a rotating magnetic recording disk to a magnetic recording slider is developed using molecular dynamics simulation. The combined effect of disk velocity and local air-bearing pressure changes on lubricant transfer is investigated. The simulation results indicate that local pressure changes in the absence of disk circumferential velocity can cause lubricant redistribution on the disk, while local pressure changes on a moving disk can result in lubricant transfer from the disk to the slider. The amount of lubricant transferred from the disk to the slider and the lubricant buildup on the disk are a function of the local pressure change and disk velocity. The amount of lubricant transferred from the disk to the slider and the height of lubricant buildup on the disk surface decrease with an increase in the number of functional groups of the disk, a decrease in the local pressure change, and a decrease in the disk circumferential velocity.

Effects of specific key environmental factors on the life expectancy of optical data carriers

ABSTRACTIn recent years, the concept of content preservation rather than carrier preservation has become the norm with regard to long-term digital preservation. Nonetheless, the life expectancy of digital carriers is important because, in addition to other digital system parameters, it determines the migration time of digital content. In general, a cleaner, cooler, drier, and more stable environment extends the life expectancy, and appropriate protection of individual types of carriers is based on understanding the vulnerability of the carrier and consequently on providing optimal storage conditions and appropriate handling. This paper presents the effects of specific environmental factors (i.e., temperature, humidity, and light) on the life expectancy of physical digital recording media, with an emphasis on optical media. Although optical discs are just one of the various methods of digital data storage today, they continue to be a popular archive medium. It should be noted that optical discs are not permanent recording media, as is often wrongly believed, and that their life expectancy is significantly influenced by environmental factors. At the ZRC SAZU Institute of Ethnomusicology, an experiment was conducted to analyze the durability of digital records saved on CD-Rs that were exposed to light in everyday working conditions. The results showed that exposing recordable optical discs to light, especially direct sunlight, can result in complete destruction of the data recorded within a few days or weeks. This confirmed the importance of careful handling, appropriate storage, and regular testing of digital carriers.

A Novel Active-Head Slider With a Shear-Mode PZT Actuator and Dual Thermal Actuator

The active-head slider technology has recently been implemented in magnetic recording disk drives to reduce the flying height at the read/write element. The two typical actuators to drive an active-head slider are thermal actuator and piezoelectric actuator. This work proposes a novel `TFC-TPC' active-head slider actuated by a piezoelectric actuator and dual thermal actuator. The electromechanical simulation and thermal-structure simulation coupled with air bearing simulation are used to simulate the actuation by the piezoelectric actuator and dual thermal actuator, as well as the effects on flying performance of slider being actuated. The simulation results show that the proposed slider design can take full advantages of piezoelectric actuator and dual thermal actuator, to obtain a fast and flexible control of flying height of slider in hard disk drive.

Spreading Kinetics of Lubricant Droplets on Magnetic Recording Disks

The spreading of droplets of perfluoropolyether lubricants is studied on unlubricated, carbon-overcoated disk surfaces, the type used in magnetic recording disk drives. As the number of hydroxyl end groups on the Fomblin-Z backbone is increased from zero to two to four (Z → Zdol → Ztetraol), the spreading kinetics slows down dramatically for each addition of two hydroxyl end groups, and with eight hydroxyl groups, the lubricant ZTMD no longer spreads. Faster spreading kinetics is observed initially when a central droplet is still available to feed lubricants into the molecularly thin lubricant film. Much slower spreading kinetics is observed once this central droplet has dissipated to form a pancake-shaped film less than a monolayer thickness. During the initial spreading stage with the central droplet, the radius R of the area covered by the spreading film grows as R ~ t ν , with ν ~ 1/3, while during the final spreading stage, ν ~ 0.1. The faster spreading mechanism during the initial spreading stage is attributed to the en masse flow of lubricant molecules in the lubricant film driven by the backing pressure of the lubricant remaining in the droplet. The slower spreading kinetics once the central droplet has dissipated is well described by a thickness-dependent diffusion coefficient D(h) obtained by modeling lubricant migration as Poiseuille flow driven by the disjoining pressure gradient.

Simulation for a Shingled Magnetic Recording Disk

Shingled magnetic recording (SMR) is a new technology based on partially overlapping, or shingling, adjacent tracks, which is capable of increasing the density of a disk drive up to 10 Tbit/in <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . To write data on overlapping tracks may erase data being written previously. Therefore, without any data translation layer to redirect updates to different locations to avoid unintended data erasures, the SMR disk cannot be used as a conventional disk to perform unrestricted reads/writes directly. Various data translation/mapping strategies have been proposed to allow the disk to perform unrestricted reads/writes. However, these strategies have tradeoffs in terms of system performance and cost, such as disk space utilization. Nevertheless, system performance varies for different applications and under different workload conditions. To help optimize the design of a data translation layer for a SMR disk, simulation software is required to analyze tradeoffs and to fine tune parameters for data translation/remapping strategies. We have designed and developed a simulation software for SMR disks. This software can analyze both system performance and disk space utilization. The SMR disk simulation uses the shingled disk profiles generated from the conventional disk profiles which have been experimentally validated. Evaluation studies show that the simulation software can accurately simulate SMR disk performance. This software will be a useful platform to design and test the shingle translation layer (STL) for a SMR disk with different disk layouts and data management strategies and garbage collection algorithms.

Thermal Effect of a Thin Overcoating Layer Subject to Laser Heating

This paper concerns the effect of a thin overcoating layer on the temperature increase in heat-assisted magnetic recording disk structure induced by laser heating. The optical absorption model, which derived from Maxwell's equation, is applied to quantify local energy absorption by the media. The numerical simulations indicate that the presence of a 2-nm overcoating layer results in additional 5% temperature increase in the disk, compared with the same media structure without overcoating layer. This temperature increase is resulted from the laser energy absorbed by the overcoating layer and the low thermal conductivity of the overcoating layer. The temperature difference between the overcoating layer and its neighbor layer is negligible small. This paper indicates that besides its mechanical properties, the thermal and optical properties of the overcoating material are important design factors.

ZnO electrodeposition onto gold from recordable compact discs and its use as photocatalyst under solar irradiation

A ZnO film was electrodeposited onto a gold substrate obtained from a recordable compact disc and tested as photocatalyst in degradation of dye in aqueous solution. X-ray diffractometry and atomic force microscopic analysis showed a pure ZnO phase with particle sizes in the nanometric scale. The results showed that the photocatalytic activity of the film is significant, with more than 90 % degradation of the dye in under 6 h sunlight irradiation. The photocatalytic process in sunlight follows first-order kinetics.

International Standards and off Line Archiving Through the use of Recordable Optical Discs

What does the phrase &#x201C;CD-R, DVD-R Recordable Optical Discs&#x201D; bring to mind? Does it have negative connotations like &#x201C;old technology&#x201D;, &#x201C;limited capacity&#x201D; or &#x201C;unreliable archiving?&#x201D; If it does, then you need to take another look at this technology. Recordable optical disc technology is an established technology that is widely regarded as a state-of-the-art solution used on servers, medical instrumentation and for &#x201C;must not be altered&#x201D; data storage needed for trials and law enforcement records. Furthermore, DVD-R capacity (4.7 GB) is enough to store approximately 20,000 PDF pages, assuming 250 KB per page (up to 50,000 pages with compression). It is also enough capacity for 120 minutes of digital master sound data (24-bit, 96 kHz). DVD-R's are an excellent storage solution and provide sufficient capacity when organization size and purpose is taken into consideration. DVD-R is also a solution for long-term archiving. We will discuss three extremely important things you should know about archiving using recordable optical discs.

Voltammetric behaviour of hydrogen peroxide at a silver electrode fabricated from a rewritable digital versatile disc (DVD) and its determination in water samples

In this study we investigated the possibility of applying Ag electrodes manufactured from recordable rewritable digital versatile discs (DVD-RW) for the voltammetric determination of hydrogen peroxide. The calibration plot was linear from 0.087 mM to 3.41 mM hydrogen peroxide with a sensitivity of 58.7 μA mM−1 over this range. A corresponding detection limit of 78.35 μM, based on a signal-to-noise-ratio of 3 was recorded. No interferences were observed by 500 mg L−1 chloride, 50 mg L−1 nitrate, 700 mg L−1 sulphate or 700 mg L−1 carbonate which are found in swimming pool water at these concentrations. Using the multiple standard addition method a percentage recovery of 90.67% with a coefficient of variation of 4.69% (n = 5) was found for a representative swimming pool water concentration of 1.2 mM hydrogen peroxide. Therefore, the performance data suggests that the method is reliable at the concentrations examined in this study and that a rapid, simple, economical and precise method of monitoring hydrogen peroxide in swimming pool and aquaculture applications is possible.

Temperature profile of the multilayer structure irradiated by pulsed laser

Two programs are developed to calculate the tem- perature profile, as well as the reflectance, transmittance and absorption of a given multilayer film structure, in order to better understand the laser energy distribution between the reflectance, transmittance and absorption in each film layer. An inorganic Blu-ray recordable disc (BD-R) structure is used as a practical demonstration of the multilayer struc- ture. The reflectance and absorption of the BD-R structure exhibit opposite trends and oscillate repeatedly with varying lower or upper dielectric layer thickness while the rest of the film thickness remains unchanged. The energy absorption in an absorbed layer depends on the thickness of the dielectric layers, its relative position in the structure and the extinction coefficient of its optical constant. The total absorption ratio of its maximum to minimum can be over 3 when changing the lower dielectric layer thickness of the studied structure. The layer thickness acts as an energy valve to control the energy flow into the multilayer structure. The thermal pro- file of the multilayer film structure irradiated by a pulsed laser is calculated at different positions in the film layers with time. The calculated temperatures in the recording al- loy layer exhibit linear relationship with the applied power level. The effect of the laser duration time on the tempera- ture increase in the recording layer is significant in the first few nanoseconds and becomes saturated if the heat balance is established in the structure. The calculated temperature is consistent with the experimental recording result when the structure is recorded at 4-time BD-R recording speed.

A label-free immunosensor based on recordable compact disk chip for early diagnostic of the dengue virus infection

The non-structural protein 1 (NS1) of dengue virus is abundantly circulating in the blood during the acute phase of the dengue infection being correlated with viremia levels and hence can be used to early diagnostic of the dengue hemorrhagic fever. An electrochemical immunosensor based on gold film electrode obtained from a recordable compact disk (CD-trode) was developed for NS1 protein. Anti-NS1 monoclonal antibodies were immobilized on the CD-trode via protein A. The stepwise immobilization of the anti-NS1 was characterized by cyclic voltammetry and electrochemical impedance spectroscopy. The analytical response to the NS1 interaction with anti-NS1 immobilized on CD-trode was detected by applying the differential pulse voltammetry technique. The immunosensor showed a linear response from 1 to 100ng/mL of NS1 and a detection limit of 0.33ng/mL. This label-free immunosensor exhibited a good reliability for NS1 detection in serum samples presuming an early diagnostic of the dengue virus.

Parametric simulation of piezoelectric flying height control slider using shear-mode deformation

The piezoelectric flying height control slider has recently been implemented in magnetic recording disk drives to reduce the flying height. This paper performs the electromechanical simulation and air-bearing simulation to investigate the effects of the shear-model deformation on the static flying attitude of PZT slider. The location of PZT sheet and air bearing surface of slider are investigated to achieve a low flying height and robust head-disk interface. The results show that a short distance of the PZT sheet to the trailing edge of the slider can help to achieve a low flying height. A small center-trailing pad of the slider can also help to achieve a low flying height, but cannot prevent the reduction in pitch angle. The depth of the center-trailing pad does not change the reduction ratio of the pitch angle when increasing the drive voltage. A big pitch angle value is needed to avoid the pitch angle falling below zero at a high drive voltage.

Data Loss and Demagnetization of Perpendicular Magnetic Recording Disk Under Sliding Contact

Data loss and demagnetization of perpendicular magnetic recording disk under sliding contact were investigated experimentally. The data loss tests of the disk against a diamond tip under normal forces (0.005–0.05 mN) and the scan of the disk with the magnetic head were sequentially carried out. Then, the demagnetization tests under normal forces (6–10 mN) were performed on the disk to examine the demagnetization behavior. After the tests, the sliding contact areas in the disk samples were observed by atomic force microscopy and magnetic force microscopy. The results showed that data loss occurred without any scratch damages on the disk and demagnetization of the magnetic medium did not occur in the data loss area. The demagnetization occurred only when the scratch depth in the disk exceeded the thickness of the diamond-like-carbon top layer. Finally, a method to study the relationship between data loss and demagnetization of the perpendicular magnetic recording disk under sliding contact was proposed and the conclusion was given that data loss of the disk was not induced by demagnetization of the magnetic medium.

Impedimetric Aptasensor for Thrombin Recognition Based on CD Support

AbstractWe report an aptamer biosensing array for thrombin detection by measuring the electrochemical impedance upon aptamer‐protein formation at the surface of CD‐trodes (GCDTs) in the presence of the redox couple [Fe(CN)6]3−/4−. GCDTs are fabricated from recordable compact discs that contain a fine gold layer. The biosensor is constructed by self‐assembling of a thiol‐modified thrombin binding aptamer (TBA) onto a GCDT surface. The sensor reveals good ligand specificity, recognition in a wide range of thrombin concentrations from 20 nM to 1 µM with a limit of detection of 5 nM.

ディジタル・ヴァーサタイル・ディスク・レコーダブル用オキソノール色素の熱化学的性質の制御--高速記録時の熱的干渉の抑制

ディジタル・ヴァーサタイル・ディスク・レコーダブル用オキソノール色素の熱化学的性質の制御--高速記録時の熱的干渉の抑制

OS6-2-3 水晶振動子マイクロバランスを用いた固体表面近傍液体の粘弾性評価 : 固液界面接触面積の影響(OS6 マイクロナノトライボロジー(2))

Lubrication by a molecularly thin film has become very important in micro machines, magnetic recording disks and so on. When, the thickness of the lubricant film is thinned to several nanometers, physical properties of the film would become different from that of the bulk. Therefore it is important to know these properties. Quartz crystal microbalance (QCM) is common in thin film growth, where it is used for film thickness measurements. The quartz crystal oscillates in transverse shear mode near its resonant frequency that is affected by the adsorbed mass of non-viscous elastic film or the viscosity and the density of the adsorbed liquid. By using this relation, QCM allows one to evaluate viscoelastic properties of adsorbed layer on a surface.

Archiving Solution with Optical Disc

Ever since the dawn of human being, variety of media such as stone, parchment, bamboo, woods, paper, magneto, optical and electric has been used for recording information. Among those, the optical discs initially started from audio CD in early 1980s, has 12 cm diameter, still playing prominent roles for long term with its stable format, despite the continued evolution of electronic products. The recordable optical discs has also been used for data storage and data distribution for more than 20 years showing its continued strong demand over 10 billion discs every year. Its applications are broadly ranged such as audio, video, PC and digital information.Though optical discs have less capacity and slower transfer rate than hard disk drives and magnetic tape, they have great deal of potential for application of long term archiving.This report discusses the use of optical discs as archiving media and trends in its standardization towards it. As an example, this paper also examines the recovery of discs damaged by the Great East Japan Earthquake.

A ‘Social Form Of Knowledge’ in Practice: Unofficial Compiling of 1960s Pop Music on CD-R

In this article I explore the ‘unofficial’ (and technically illegal) compiling of marginally known 1960s pop records on Compact Disc Recordable (CD-R). I do so by situating it within the proposition by the late Raphael Samuel, that history is ‘social knowledge’ and a practice rather than a profession. I propose that this compiling activity exemplifies this proposition. The core of the paper is centred on a 2007 survey which I conducted via three on-line 1960s music enthusiast discussion forums. I draw on the sixteen responses to demonstrate how the motivations, values and intentions of those respondents engaging in the practice of CD-R compiling are historically and socially centred. In doing so, I seek to problematise the music industry’s undifferentiated condemnation of all copying as theft. I do so by showing how, far from stealing, these CD-R compilers are adding to the musical social knowledge of 1960s pop and rock music. I further situate them within a longer lineage of ‘unofficial listening’ dating back to at least the 1930s. In using the term ‘unofficial’ in both a legal and public historical sense (eg to take issue with a received narrative), I point to wider definitions of what historically has or has not been musically ‘official’ to listen to. I seek also to point to the practice of CD-R compiling as a historical ‘moment’ in technological change, which might otherwise go unremarked upon as the CD-R itself heads towards utilitarian obsolescence. Although, the issues and concepts raised in the paper can be little more than pointed to, it is hoped it might act as one platform for the historical engagement with a subject more commonly discussed in sociological terms. As public historians we should be reflexive and inter-disciplinary and it is with this mind set that this article is written.