We developed a new head and tape interface in stationary head tape system. This system consists of two important parts, a plate and a small head. Motion of the tape which runs along the plate generates air flow between them. This air flow reduces the tape vibration on the plate. Small head slides on the tape steadily because the tape vibration is very little. This tape and head interface keeps the low spacing even if the tape speed increases. This method realizes the higher data transfer rate and higher recording density with high tape speed.

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The varieous values about the spacing loss factor K have been reported on the combination of obliquely evaporated tape and ring-type head. In this work, we studied the influences of medium orientation angle, recording current and recording wave length to the spacing loss factor K by finite element method of computer simulation. The K value including writing and reading varies from 65 dB to 100 dB as the orientation angle increases from 10 degrees to 45 degrees. Also the K value depends on the recording wave length. It become larger as the wave length becomes longer.

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In order to achieve the required frictional properties in particulate media, the adequate amout of surface lubricant is investigated. By using newly-synthesized perfluoropolyethers (PFPEs) in particulate media, the amount of surface lubricant is evaluated by X-ray photoelectron spectroscopy (XPS) and contact angle measurements. It is necessary for friction reduction to have not only large coverage ratio of the outermost surface by lubricant but also the sufficient amount of sub-surface lubricant. Comparing internal and topical lubrication, the topical coated media have larger coverage ratios that lead to lower friction coefficients. The migration rate of the lubricant is evaluated as the recovery rate of the XPS peak height. Lubricant of higher recovery rate has better stability with regard to friction in storage of the tape under accelerated conditions.

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In sputtered magnetic media, reducing the crystal grain size and intergranular coupling is necessary to achieve higher recording density. However, as grain size becomes finer, the thermal influences on the magnetic properties increases. The time and temperature dependence of remanence coercivity was investigated to examine these influences. In the high fluctuation-field media, the demagnetization of remanence with time increases, even if the medium coercivity is very high (>2000 Oe). The temperature coefficient of coercivity also increases with increasing thermal fluctuation. More essential and extensive studies on thermal stability are required to develop higher-density magnetic disks.

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The neural network equalizer is known as a nonlinear equalizer with which the effective equalization can be achieved. In this report, we have examine a capability of this equalizer for actual waveforms in perpendicular magnetic recording. As a result, a signal of high normalized density of about four can be successfully equalized with low error rate. In addition, it was confirmed that the overwrite transition shift can be completely suppressed, based on an analysis using pseudo-random sequence.

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A high-order partial response (PR) that is generally represented by (1+D)(1-D^n) and that will provide both high density and high speed in HDD signal processing is proposed. By using a pre-coding 1/(1+D), the n-bit interleaving operation for high-speed processing can be used. When n=3,the equalization noise gain is about 4 dB higher than in the conventional PR4 at a channel density of 3.0,and the same squared Euclidean distance as with the PR4ML is attained in a 3-bit interleaving maximum likelihood detector. High-order PR channels for perpendicular recording are also proposed.

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