Toshio Shirai

Magnetoresistive heads for helical-scan tape systems

In this paper, the helical-scan tape systems using the shielded MR heads will be discussed. We studied the issues related to the head/tape contact including the thermal asperity and the head wear. The study suggests that these issues can be resolved to the allowable level in the practical system. In this study, we have successfully demonstrated a high recording density using MR heads in these systems.

Reliability tests of the MR head in helical-scan tape systems

In a helical-scan tape system, the MR head is brought into contact with the tape surface at high speed and is exposed to the atmosphere without a protective coating. In this paper, we study the contact resistance between the MR head and tape in terms of tape surface resistance and voltage applied to the head. The electrostatic charge that accumulates on the tape surface as a result of running the tape was measured and found to be less than a few volts. Corrosion tests were found to cause no electrical damage and no visual change, and the block error rate remained constant after storage for 1 year and 5 months. We conclude that helical scan tape systems using the MR head are reliable.

High-density recording using MR heads in helical-scan tape systems

This paper presents the application of magneto-resistive (MR) heads to the helical scanning tape system. After we discuss some problems including the contact between the MR head and the Co-O evaporated (ME) tape, we report a feasibility of a high-density recording in the helical scanning tape system using MR heads.

Track profile of MR head and its performance in a helical scan tape system

The MR head is being studied for use in helical-scan guardband-less tape systems. These systems need a read head with a wider track width than track pitch, so the track profile of the head is important. We analyzed the track profile of MR heads, and found that fluctuations in the reading signal are not an issue. We then mounted the head on a tape-streamer drive and measured the SNR. We found that the MR head provided an SNR which makes it possible to double the areal density with a margin more than 6 dB over that of an inductive head.

A narrower side erase band for use with helical scan tape systems

The MFM technique is very useful to measure the side erase band. MFM images were processed by FFT to measure the side erase band width and effective track width. Compared with the electromagnetic properties produced using the MR head, the measuring point is defined on FFT processed data. Mrt of the tapes (thickness of magnetic layer), type of recording head and recording frequencies were varied for the sample tapes. The track width of low Mrt tapes showed good stability in different combinations of recording frequency. The side erase band width was reduced when a trimmed MIG head was used. The influence of the recording current for the side erase band was negligible.

Recording characteristics at a channel rate over 300 mb/s in a helical-scan tape system

Recording characteristics at high-linear density were investigated using a spin-stand tape tester. Low-noise metal obliquely evaporated tape with a 40-nm magnetic layer was used. Read signal level and nonlinear transition shift of a thin-film head was compared with that of a metal-in-gap head. A prototype helical-scan tape drive with a thin-film head and a giant magnetoresistive head was developed to investigate the recording characteristics at channel rates over 300 Mb/s. A sufficient signal-to-noise ratio of 18 dB was obtained at a channel rate of 300 Mb/s with a read track width of 0.8 /spl mu/m and a linear density of 376 kFRPI.

Recording at a channel rate of over 200 Mb/s in a helical-scan tape system

In order to increase the channel rate in a helical-scan tape system, we have studied its recording characteristics using a magnetoresistive read head, a metal-in-gap write head, and a metal evaporated tape, and transmission through a rotary transformer. A sufficient signal-to-noise ratio for the streamer system was obtained in a test drive at a channel rate of 200 Mb/s. The potential of achieving a channel rate exceeding 200 Mb/s using a thin-film write head was also investigated.

A recording at a channel rate of 200 Mbps in helical tape systems

Summary form only given. We have reported a helical-scan tape system using MR heads as read heads. In this work, we have studied a tape recording at a channel rate of 200 Mbps, which is about double that of the current recording tape-streamer. By using MR heads and low noise ME tape, we have improved the performance of the CNR of the high clock-rate read channel. The impedance noise spectrum of the MR head is flat. The media noise is dominant in the total noise. The power of the media noise is kept constant at various recording rate.