High Density Recording Technology Research Articles

Back heating effect of media hot spot at nanoscale head–disk interface

Heat-assisted magnetic recording (HAMR) is one of prospective high density recording technologies in current hard disk industry due to its theoretical potential. In this paper, we develop a new heat transfer model which enables us to predict near field thermal conduction and radiation across head–disk interface accurately. This new model, together with an Ansys finite element (FE) model for an integrated HAMR slider and an optical absorption model for temperature profile of media hot spot, is then used to solve for temperature rise and thermal protrusion on the slider body. Our simulation studies show that larger hot spot and smaller head–disk spacing will increase the temperature and thermal protrusion on the slider’s head components. When thermal radiation effect is further considered, this increment in temperature and protrusion becomes more significant; especially at very small gap below 1 nm. Therefore, the back heating effect from media hot spot should be addressed carefully for improving the reliability of HAMR head–disk interface.

Numerical investigation of thermal effects on a HAMR head-disk interface

Heat-assisted magnetic recording (HAMR) is one of prospective high density recording technologies in current hard disk industry. In this paper, we incorporate HAMR optical structures into a finite element model of a thermal flying height control slider and study thermal effects of these structures on the HAMR head-disk interface. Our focus will be on the slider flying height (FH) changes due to the heat loss in the waveguide and near field transducer (NFT). According to our results, we find that large heat dissipation in NFT alone could affect the slider's FH due to the additional thermal protrusion induced around the writer. The heat dissipation in the waveguide could also influence on FH drop. In addition, the media back heating effect on the slider temperature and thermal deformation is also analysed in this paper. The numerical result shows that the respective thermal deformation caused by media back heating is about 0.09 nm with 72 nm of heat spot size. This amount could be significant when the slider's FH is below 1 nm. Therefore, it is very important to improve the efficiency of laser optical delivery system and reduce thermal effects on a HAMR head-disk interface.

Direct Monte Carlo simulation of air bearing effects in heat-assisted magnetic recording

Heat-assisted magnetic recording (HAMR) is a promising high density recording technology in current hard disk industry. It is proposed to use a heat source from the slider system for heating up the recording media in order to increase its storage density. The heat generated from a heat spot on the disk and/or the higher slider body temperature in HAMR system could affect the slider air bearing and flying height. This paper studies the heat effects on slider air bearing characteristics by using the direct Monte Carlo simulation (DSMC) method. The simulation results show that the heat spot less than 50 nm in diameter could not affect much to the air bearing; however, its location should be away from the bearing pressure peak to minimize the heat spot effect. Furthermore, high temperature slider could increase the bearing pressure and force and the trend of force increment is independent of the flow channel length.

Magnetic Imaging. Excuse Me, What is Relevant for High Density Recording Technology?

Extended abstract of a paper presented at Microscopy and Microanalysis 2006 in Chicago, Illinois, USA, July 30 – August 3, 2006

Development of NanoCAP technology for high-density recording

For high-density recording tape, NanoCAP was developed using co-precipitation and nitridation treatment in an NH/sub 3/ gas atmosphere. Each particle has a spherical shape with a diameter of about 17 nm and a core-shell structure. The core and shell mainly consist of the Fe/sub 16/N/sub 2/ and oxides containing Al and Y, respectively. The saturation magnetization and the coercive force are 85.5 A/spl middot/m/sup 2//kg (85.5emu/g) and 227 kA/m (2850 Oe), respectively. The coercive force is a higher value that of the needle-shaped particles currently used and is stable from room temperature to 323 K. The higher coercive force originates from an uniaxial magnetic anisotropy of the Fe/sub 16/N/sub 2/.

Storage technology for television home server

The progress of high-density recording technology has brought about new fields in storage applications. A television home server is a home storage system for the age of digital broadcasting. It records the viewer's favorite programs automatically for subsequent viewing at any time. We propose an architecture for the home server realizing a high-speed recording/ playback capability with very large capacity.

高密度光ディスク記録技術

高密度光ディスク記録技術

High density magneto-optical disk technologies

Many types of high density recording technologies have been proposed in the field of magneto-optical recording to satisfy demands of storing a large amount of digital information. Magnetically induced super resolution (MSR) is one of the most hopeful technology. However, trials of using the MSR technology in a realistic magneto-optical system were not fully investigated. Previously, we reported the concept and fundamental results of experiments and calculations of a high density magneto-optical recording system using a combination of a center-aperture-detection type of MSR (CAD-MSR) disk and other technologies. In this study, we have improved each of the technology discussed in our previous report. Moreover, we have evaluated the feasibility of magneto-optical disk systems which have a 4 Gbit/in/sup 2/ density with taking account of the margins.

Tapeless and Tape Recording Technologies for Desktop Program Production

This paper reports on the concept and configurations of the desktop program production (DTPP) system and specifications of the storage system for the multimedia data base in the DTPP. The current technologies of VTRs, hard disks, and magneto-optical disks for the storage system, as well as the latest research results related to high-speed and high-density recording technologies, are also introduced.

Characteristics of high-density recording using a single-layer perpendicular medium and a merged MR head

The combination of a merged MR head and a single-layer perpendicular medium is a promising technology for high-density recording. This paper describes a system that provides high-linear-density recording (over 150 kFCI) without requiring a contact recording method. Both-the large magnetic anisotropy and the large crystalline orientation of a Cr-rich Co/sub 72/Cr/sub 28/ medium hold out the promise of higher linear density. The large output signal also shows the possibility of increasing the track density. The baseline shift for narrow track widths is an issue that must be solved by equalization before this system can be used to realize future hard disk drive products.

An experimental digital VCR for consumer use

An experimental digital VCR (DVCR hereinafter) was developed. The DVCR has two new technologies for reduction of tape consumption. One is a bit rate reduction technology of a component video signal down to around 25 Mbps and the other is a high density recording technology. The bit rate reduction technology is based on an 8/spl times/8/2/spl times/4/spl times/8 two dimensional DCT (Discrete Cosine Transform) and a VLC (Variable Length Coding) that completes over 5 macro blocks. Editing, trick plays and invisible error concealments also have been realized by this bit rate reduction while keeping the playback picture quality very high. The high density recording technology is based on ME tape and an ATF (Automatic Track Finding) system. A track pitch of 10 /spl mu/m and a bit length on tape of 0.25 /spl mu/m have been realized. The possibility of a higher linear recording density has been confirmed through theoretical analysis, simulations and experiments.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

映像機器のメカトロニクス 家庭用ディジタルＶＴＲに用いられる炭素保護膜付き蒸着テープのトライボロジー

The lubricity, durability and anti-corrosive properties of metal evaporated tape (ME tape) for digital VCRs were investigated. To improve reliability of the ME tape, Diamond-Like Carbon (DLC) film and lubricant were applied as protective layers on a Co-O magnetic layer. This newly developed ME tape has on output +5.0 dB higher than conventional Hi-8 ME tape for a recording density of 100 kBPI. Its still frame life was over 10 hours. The key development of this DLC film is the application of high Vickers hardness and uniform morphology as a protective layer and partially fluorinated alkyl carboxylic acid as a lubricant layer on the film. Even if the surface roughness of the ME tape is low, excellent running durability, still frame life and corrosion resistance are obtained from the combination of effects from the DLC protective layer and the lubricant layer. This ME tape plays a major role in determining consumer-use digital VCR specifications and will help advance the next generation of high density recording technology.

Application of Optical Disks to Digital Color Video Recording

Magnetooptic disks offer many advantages such as large capacities, rewrit-ability, and random access. However, the storage capacities and data transfer rates of magnetooptic disks are not yet adequate for application in color video recording. There are two approaches to the application of magnetooptic disks to color video recording. One involves improvement of the storage capacity and data transfer rate of the magnetooptic disks; the other relies on image data compression techniques. We review stacked optical disk files and high-speed, high-density recording technologies as examples of the former approach. We then describe a multimedia filing system using stacked optical disk files, which can record and reproduce video and audio information in an integrated manner. Finally, we describe a color video data compression technique and explain the suitability of magnetooptic disks for packaged video media.

A high density recording technology for digital VCRs

High-density recording using high-performance ME (metal evaporation) tape, a Viterbi decoder in the playback circuit, and a novel mechanism for tape transport is described. These developments have made it possible to realize an areal density of 1.35- mu m/sup 2//bit (479 Mbpi/sup 2/).< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Signal processing of a 20-bit 8-channel digital audio recorder

The digital multichannel recorder, a PCM (pulse code modulated) audio recording unit, is described. An 8-PCM-channel with 20-bit/sample data slot is available at the sampling frequencies of 48, 44.1, and 32 kHz. High-quality recording and editing functions are provided for semiprofessional and superior amateur use. The newly developed thin-film magnetic heads and the high-density recording technology enable more than 20 minutes' recording on 8-mm tape loaded in a compact-size cassette. The features and signal processing technology of this digital audio recorder are described.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The effect of Cr and W nucleation layers on the magnetic properties of CoPt films

CoPt and CoCr alloy films have received considerable interest recently for use as recording media in high-density recording technology. Chromium films have been used as nucleation layers to improve the magnetic properties of hcp magnetic alloy films (CoNi, CoNiCr, and CoCr) by increasing the in-plane c-axis preferred orientation. In this investigation, Co80Pt20 magnetic films were deposited onto 1000-Å-thick nucleation layers of chromium, a chromium-vanadium alloy or tungsten. Deposition of Co80Pt20 films onto W produced a significant increase in coercivity compared to the Cr nucleation layers. Coercivity values as high 2400 Oe were observed for the W/Co80Pt20 composite structure compared to about 1900 Oe for the CrV/Co80Pt20 structure.

The Videotape Recorder: Its Evolution and the Present State of the Art of VTR Technology

The videotape recorder (VTR) is one of the most important devices available for the storage and retrieval of visual information. Since the introduction of the first commercially successful broadcast VTRs in 1956, improvements in VTR technology have been directly and exclusively related to increases in the recording density on magnetic tape. Modern high-density recording technology has resulted in many remarkable products and techniques, including high-quality broadcast VTR equipment, inexpensive and convenient home-use VTRs, and extremely compact camera-video equipment. The overall performance of VTRs is rapidly improving as the latest techniques of digital technology and LSI devices are incorporated in such innovative approaches as frequency modulation and the pulse-code modulation recording method. This article discusses the developmental background of the VTR and the latest VTR technology.

Magneto-optic recording technology (invited)

Magneto-optic recording has great potential as an erasable/rewritable storage technology. Bit densities of 108/cm2 are being achieved and improvements can be expected. This paper reviews the status and discusses the most critical issues of the technology. It is shown that the fundamental broadband signal-to-noise ratio in existing rare-earth transition-metal media is well above 20 dB and therefore adequate to maintain error rates less than 10−12. Substrate imperfections in optical media lead to error rates of 10−5–10−6, but even these relatively high raw bit error rates are corrected to 10−13 by error correction codes and hardware being used in write-once optical disk storage systems. The stability of magnetic domains recorded into magneto-optical materials may be explained by a model involving wall energy, demagnetizing fields, applied fields and wall coercivity, and there exist materials which fulfill the requirements necessary to have recorded data remain stable against fields up to 100 Oe and temperatures from 0 to 100 °C. Of more concern is the stability of the amorphous thin films against long-term annealing. Passivation with optical dielectrics is essential, and preliminary data on some rare-earth transition-metal alloys indicate that recorded data would be stable for five years when stored at 50 °C and that the media could withstand in excess of 1010 write/erase cycles with less that 10% change in minimum stable domain size. It is concluded that magneto-optic recording technology is a promising high-density recording technology with a place in the digital storage hierarchies of the future.

A New Concept of Handy Video Recording Camera

High density recording technology is going to realize the very compact VCR system. And all solid state color video camera which has many advantages over conventioal tube type cameras, e. g. light-weight, low power consumption, high reliability, lag elimination and high picture quality, has been developed.1) The authors have developed a handy video recording camera-the MAG CAMERA, which is shown in Fig. 1. This camera features two newly developed technologies; high density two hour recording system and all solid state color camera with single-chip MOS imager. The combination of above two technologies realized the unprecedented performance with compactness and handiness comparable to 8 mm movie cameras.