Hitachi Maxell, Limited

Akiyoshi Itou

Norio Ohta

Katsusuke Shimazaki

Hiroyuki Awano

Hiroki Takao

Katsuji Nakagawa

Masafumi Yoshihiro

Manabu Tani

Masaki Sekine

A magneto-optical recording medium has magneto-optical recording layers () and reproducing layers (). The information recorded in the reproducing layers are reproduced by means of reproducing light beams () of different wavelengths, respectively. In reproduction, magnetic domains () recorded in the recording layers are transferred in the reproducing layers formed on the respective recording layers, the transferred magnetic domains () are enlarged with an external magnetic field, and the information is reproduced. Since information is recorded and reproduced for each recording layer, the recording density is improved. Further since the reproduction signals are amplified by the magnetic domain enlargement, the C/N is improved.

Magneto-optical reproducing method using a plurality of different reproducing beams

A magneto-optical recording medium has magneto-optical recording layers ( ) and reproducing layers ( ). The information recorded in the reproducing layers are reproduced by means of reproducing light beams ( ) of different wavelengths, respectively. In reproduction, magnetic domains ( ) recorded in the recording layers are transferred in the reproducing layers formed on the respective recording layers, the transferred magnetic domains ( ) are enlarged with an external magnetic field, and the information is reproduced. Since information is recorded and reproduced for each recording layer, the recording density is improved. Further since the reproduction signals are amplified by the magnetic domain enlargement, the C/N is improved.

Magneto-optical reproducing method using a plural of different reproducing beams

The magneto-optical recording medium has a magnetic domain magnification reproducing layer and an information recording layer. Clock marks are formed on the information recording layer, making it possible to generate a reproducing clock on the basis of these. The clock marks are detected either by irradiating directly with light of wavelength &lgr; (&lgr; &ne;&lgr; ), being different from the light of wavelength &lgr; which is used for reproducing the recording marks, or by applying a direct-current magnetic field, transferring and enlarging the clock marks on to the magnetic domain magnification reproducing layer, and detecting the reproduction signals from this magnetic domain magnification reproducing layer. Since the reproducing clock is in exact synchronisation with the recording marks, it is eminently suitable as a clock for pulse-modulated reproducing light and reproducing magnetic fields used when reproducing the reproducing layer.

Magneto-optical recording medium having clock-marks on recording layer and apparatus for recording and reproducing same

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Matsudo, Japan

Akiyoshi Itou