Hitachi Maxell, Limited

Norio Ota

Katsusuke Shimazaki

Teruaki Takeuchi

Hiroyuki Awano

Osamu Ishizaki

Satoshi Matsunuma

Reiji Tamura

Toshiaki Taii

Yoshihiro Ikari

In an apparatus for recording and reproducing a thin optical disc by using the same optical system as that of a CD, a DVD or the like, the invention provides a technique which can stably rotate the thin optical disc at a high speed. The structure can be made such that a turbulence of an airflow is not generated even if the thin optical disc on a turn table is rotated at a high speed, by employing a transparent turn table and arranging a recording and reproducing head or the like in an opposite side to a thin optical disc mounting surface of the turn table.

Recording and reproducing apparatus of thin optical disc

A perpendicular magnetic recording medium has a substrate, a magnetic functional layer provided on the substrate, and a magnetic recording layer stacked in contact with the magnetic functional layer and having perpendicular magnetic anisotropy. &#x2212;4&#xd7;2&#x3c0;Ms&#x2266;Ku&#x2266;6&#xd7;2&#x3c0;Msis satisfied, wherein Ku represents a perpendicular magnetic anisotropy constant of the magnetic functional layer and Ms represents a saturation magnetization. The magnetic moment of the magnetic functional layer is rotated in a direction of an applied magnetic field during the recording, and the magnetic moment acts on the magnetization of the recording layer in such a manner that the applied magnetic field is assisted thereby. Minute magnetic domains can be stably retained and excellent thermal disturbance resistance can be obtained.

Magnetic recording medium having a specific relation of coercive force HC and residual magnetization MR in perpendicular direction to substrate surface

Disclosed is a phase-change optical recording medium which has a reflectance and a signal modulation conformed to the CD standard, and which is usable for recording at the same linear velocity as the reproducing velocity specified in the CD standard. The phase-change optical recording medium comprises a metallic layer, a first protective layer, a recording layer, a second protective layer, and a reflecting layer on a substrate, in which recording is performed through change from a crystalline state to an amorphous state in the recording layer. The recording layer comprises a recording material of a Ge--Te--Sb--Se system, and the recording layer has an average composition in a direction of thickness which satisfies the following relations as represented by atomic %:

Optical recording medium

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Yawara, Japan

Norio Ota