Dual spin-valve multilayers, with 3 magnetic layers, have structures of both [antiferromagnetic layer/ferromagnetic layer] and [ferromagnetic layer/antiferromagnetic layer]. We investigated the exchange couplings at the two kinds of interfeces between the Ni-Fe-Co ferromagnetic layers and Fe-Mn antiferromagnetic layers. When the Fe-Mn antiferromagnetic layers were formed on the Ni-Fe-Co ferromagnetic layers, the strength of exchange couplings became almost constant at the thicknesses of the antiferromagnetic layers above 10 nm. When the ferromagnetic layers were formed on the antiferromagnetic layers, the roughness of the interface between the ferromagnetic layer and the antiferromagnetic layer increased and the alignment of the spin of the antiferromagnetic layer deteriorated at the thicknesses of the antiferromagnetic layers above 20 nm. These deteriorations decreases the strength of the exchange couplings.

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Microstructure and corrosion resistance of Fe-Hf-N soft magnetic thin films developed for digital VTR and data streamer applications are studied. Fe-Hf-N films of which Bs values are more than 1.5 T, consist of microcrystalline grians. The crystalline grain sizes of Fe and Hf-N particles in a Fe-Hf-N film are determined to be 8 and 2 nm, respectively. These of Fe and TaC particles in Fe-Ta-C-Al alloy film are 10〜12 nm and 4〜5 nm, respectively. Control of Fe and Hf-N crystalline grain sizes are important to realize useful soft magnetic characteristics as well as high corrosion resistance. Unlike the case of the Fe-Ta-C soft magnetic thin film, where an addition element such as Al is added to enhance corrosion resistance, the Fe-Hf-N soft magetic thin film, where micrograin atoms are possibly dissolved in Fe crystalline grains, shows high corrosion resistance which is suitable for magnetic head applications. At the same time, N may be possibly dissolving into Fe crystal phase. As a result, A Fe-Hf-N soft magnetic thin film has a high corrosion resistance, without a additional element such as Al of Fe-Ta-C soft magnetic thin film.

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DDS format was derived from DAT as an computer application peripheral, and compared to the initial specification of 1.3GB capacity and 183kBPS transfer rate, the DDS3 format is able to realize 12GB and 1MBPS in the same compact media. The DDS3 format and the new techniques namely (1) Head Media interface to achieve high output (2) RF equaliziation and detection method using PRML (3) Timing ATF will be discussed in this paper.

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In an ATF (Automatic Track Finding) system with pilot signals for VCR (8mm VCR, for example), analog processing technology has been used. If digital processing is used, whole servo control system including drum servo can be highly integrated. To realize this, we have developed a digital processing ATF system which positively utilizes an aliasing signal generated by sampling means. In this system, the sampling frequency ranging from 102kHz to 165kHz is used, and the BPF (Band Pass Filter) which extracts two pilot signals operates by time sharing. Consequently, the required signal processing speed is reduced and the structure of circuit is simplified.

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We have developed a Digital Laser Disc which is focused on having compatibility with the conventional Laser Disc, using Multi Level Recording Technology. Instead of analog video signals, digital data is recorded to the Laser Disc as an 8 level ASK (Amplitude Shift Keying) signal. The Digital Laser Disc can be played using a conventional Laser Disc Player.

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