Advanced Tape Research Articles

Advanced multi-track tape head for high performance tape recording application

A recently developed, advanced multi-track tape head for operation in a next generation, high performance tape drive is described. This head features full thin film write elements with high moment, cobalt-based pole materials for recording on high coercivity metal particle (MP) tape, together with narrow track, shielded, dual-stripe magnetoresistive (DSMR) read elements. This presentation will discuss the global design philosophy of the head with particular attention to the design and recording performance of the read and write elements in a tape environment. The bead is capable of recording 288 tracks on half-inch, MP tape of 1625-1850 Oe coercivity at a recording density of 65 kfci. The system operates with 16 parallel data channels and includes full multi-element active track following servo. The head can be used in a full start-stop mode and read verify on the fly (read-while-write) bi-directional operating modes.

Measurement and interpretation of magnetic time effects in recording media

Magnetic time effects are highly relevant to magnetic information storage because of the large difference (up to 16 or 17 orders of magnitude) between the time scales of the recording process and the required storage stability. Magnetic time effects become more pronounced as the volume of the switching unit becomes smaller, and thus become of more practical importance as the microstructure of recording media is made finer in the pursuit of greater information storage density. Magnetic time effects taking place on time scales longer than about 10/sup -9/ s can be explained by a model of thermally assisted crossing of an energy barrier (Arrhenius-Neel formalism). Many recording phenomena can be explained within this regime. Observation of magnetization changes during exposure to a constant field (magnetic viscosity) can be interpreted to yield an estimate of the switching volume; in most cases, this volume is larger than the frequently cited activation volume. The dependence of coercivity on the time scale of the magnetic reversal precess (e.g., on the field sweep rate of a hysteresis loop) can also be used to deduce the volume of the switching unit and to estimate time effects relevant to information storage. A model and procedure for analysis of time-scale dependence of coercivity are described here and applied to typical advanced tape media, of both metal particulate (MP) and metal-evaporated (ME) composition. The resulting switching volume for the MP tape (where the microstructure is well defined) is in approximate agreement with the particle size seen by electron microscopy. The magnetic time effects are significantly stronger in the ME tape than in the MP tape. Measurement of coercivity ion at least two very different time scales (e.g., by vibrating-sample magnetometer and 60-Hz hysteresis loops) provides a convenient means of estimating the effective switching-unit volume, and hence the magnitude of the time effects to be expected in a recording application. The model also allows the estimation of the minimum particle or grain sizes that could be used with adequate stability of magnetic transitions in high-density information storage. The practical lower limit for metal-particle volume is found to be about one-fifth to one-fourth of the volume of current advanced particles.

Characterization of magnetic tapes and substrates

Ultra-thin advanced magnetic tape substrates are shown to have superior characteristics when compared to PET. In particular, PEN and ARAMID are viable alternatives to PET with elastic moduli that range from 4-5.4 GPa for PEN, and 10 GPa for ARAMID. Also, the ARAMID material is more isotropic than PET or PEN with a higher glass transition temperature of 277/spl deg/C. Thermal and hygroscopic expansion measurements show that PEN and ARAMID are typically superior to PET. Characteristics of two developmental materials (a polybenzoxazole and a polyimide) are also presented.

Development of high density recording for advanced tape streamer

A high density magnetic recording for a helical-scan tape recorder has been developed. Tape-head characteristics and a PRML-class 1 detecting method with adaptive digital equalization are discussed and a new auto tracking following technology has been proposed. Using these technologies, we have achieved symbol error rate less than 1*10E-5 at an area density of 268 Mbit/inch/sup 2/. As a result, we have successfully demonstrated an advanced tape streamer with a transfer rate of 24 Mbps and a capacity per cassette of 25 GB.

Performance of MP/sup ++/ and BaFe/sup ++/ tapes in high density recording applications

Advanced tape recording is mostly dominated by metal particle (MP) media in helical scan analog and digital configurations. In the future, narrow track thin film write/MR read fixed head systems are likely to better satisfy the requirements for fast access and wide throughput combined with high areal densities for low storage cost. For densities above 100 kfci, the present MP tapes are severely limited mostly because of the large particle sizes. The just emerging MP/sup ++/ tapes utilize much smaller particles of higher magnetization and coercivity and offer superior performance. Even higher performance is offered by the advanced Barium Ferrite (BaFe/sup ++/) tapes, which utilize very small particles of high coercivity but, with less than half the magnetization of MP/sup ++/. The highest usable coercivity is limited by write head saturation and the MR read heads diminish the advantage of high magnetization. Double-Coating technology will at the same time provide the magnetic layer thinness and impart a continuing advantage to the particulate media which will be sufficient to retard or even block any potential competition from metal evaporated tapes (ME).

Modeling of Advanced Tape Media for Ultra-High Density Recording

Modeling of Advanced Tape Media for Ultra-High Density Recording

Advanced tape cartridge handling techniques for automated MSSs

Advanced tape cartridge handling techniques are developed for an automated mass storage system (MSS) based on VHS videocassettes. This system provides a data transfer rate of 2.5 Mb/s and an average cartridge handling time of 10 s. The wearless cartridge mounting technique using a precision mechanical hand solves the problem of cartridge-case wear. The earthquake protection control technique, using a microprocessor, completely protects cartridges from even strong earthquakes. These cartridge-handling techniques improve the lifetime of the cartridge and reduce system costs. The high-reliability tape recording technique, which is based on VHS tape analysis and uses an enhanced tape/head cleaning method, solves the problem of tape wear due to repeated tape running. The tape storage durability evaluation technique based on VHS tape analysis shows that low-temperature and low-humidity storage conditions (5 degrees C, 20% RH) are best. Most of these tape cartridge handling techniques should be applicable to future MSSs.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Advanced tape mastering system: Electronic features

A new two-track technique extends the weighted dynamic range of audio tape systems to at least 76 dB below three percent Third Harmonic Distortion. Simplest techniques are employed during recording. The extended range is achieved by continuous automatic selection of the optimum track for minimum distortion or quietest background during playback.

Advanced tape mastering system: Mechanical features

A new tape transport is described which incorporates unusual features of design. Among these are: a closed-loop drive with differential capstan resulting in significantly reduced flutter in the overall band from 0.5 to 5000 cycles, gentle tape handling, easy threading, and more efficient editing. Improved mechanical performance is employed with two-track technique to provide exceptional flutter and dynamic range.