Sanyo Electric Co., Ltd.

Kenichiro Mitani

Atsushi Yamaguchi

Naoyuki Takagi

Hitoshi Noguchi

Hiroki Ishida

Morio Nakatani

Yoshihisa Suzuki

Sayoko Tanaka

A reproducing apparatus reproduces a signal recorded in a magneto-optical disk. The magneto-optical disk includes a layered structure having a recording layer, an intermediate layer and a reproducing layer. Laser light is illuminated from an optical head to the magneto-optical disk in such an intensity that no magnetic domain is transferred from the recording layer to the reproducing layer only by the laser light. In this state, alternating magnetic field is applied through a magnetic head to the magneto-optical disk, thereby concurrently causing transfer and expansion of a magnetic domain to the reproducing layer. As a result, transfer of the magnetic domain is effected with expansion.

Method and apparatus for determining power level of laser beam in magneto-optical recording device

A magneto-optical recording medium of magnetic domain enlarging/reproducing system including a recording layer and a reproducing layer, a gate layer selectively extracting each magnetic domain within the recording layer is formed on the recording layer, a magnetic field reinforcement layer reinforcing a leakage magnetic field reaching the reproducing layer is formed on the gate layer, and a blocking layer blocking an exchange coupling force from the magnetic field reinforcement layer to the reproducing layer is formed on the magnetic field reinforcement layer.

Magneto-optical recording medium with intermediate layer having a controlled saturation magnetization

A magnetic head is configured of a core and a coil wound around the core and passing current through the coil in a variable direction allows the core to have an edge generating an alternating magnetic field Hex and another edge generating an alternating magnetic field Hex . Alternating magnetic fields Hex and Hex are applied to the respective edges. Furthermore, a laser beam LB is directed such that its optical axis L matches the edge receiving the alternating magnetic field Hex , and a laser beam LB is directed such that its optical axis L matches the edge receiving the alternating magnetic field Hex . A first magneto-optical signal detected through the alternating magnetic field Hex and the laser beam LB and a second magneto-optical signal detected through the alternating magnetic field Hex and the laser beam LB are composited together. As such, an alternating magnetic field can be applied to a magneto-optical recording medium at a predetermined angle to an in-plane direction of the recording medium to accurately enlarge a magnetic domains for reproduction.

Magneto-optical disk apparatus capable of accurately enlarging and reproducing a magnetic domain and method of reproducing the same

Reproducing method for magneto-optic recording medium, and magneto-optic disk device

A magneto-optical recording medium including a substrate, a reproducing layer formed on the substrate, an intermediate layer formed on the reproducing layer, a recording layer formed on the intermediate layer and a high magnetization layer formed on the recording layer. The intermediate layer is made of a non-magnetic material, and set at a prescribed thickness so that a leakage magnetic field from the recording layer to the reproducing layer is so distributed that the intensity thereof is increased from an end to the center of its domain. The high magnetization layer is made of an alloy or a multilayer film of a noble metal and a transition metal having saturation magnetization stronger than that of the recording layer under a reproducing temperature. At room temperature, the coercive force of the recording layer is larger than that of the high magnetization layer. Consequently, transfer/enlargement from the recording layer to the reproducing layer is readily caused in this magneto-optical recording medium.

Magneto-optical recording medium simplifying transfer of magnetic domain

A magneto-optical head includes an optical member, objective lens, SIL and coil. The magneto-optical head converts a laser beam to an evanescent light and directs it to a magneto-optical recording medium. Further, the magneto-optical head applies a magnetic field to the magneto-optical recording medium. When tilt is caused, it decreases the tilt angle. The optical member refracts the laser beam to a prescribed direction to be directed to the objective lens when the laser beam is displaced from a designed optical axis. The objective lens allows the laser beam to be focused onto a point on an end face of the SIL. Further, the SIL emits the evanescent light. The optical member is arranged in contact with the optical member. As a result, a signal can accurately be recorded or reproduced even when tilt is caused to an optical disk while alleviating the problem associated with the tilt.

Magneto-optical head apparatus using evanescent light

When recording a recorded signal consisting of &ldquo;01011001110&rdquo; in a magnetooptical recording medium, (1,1) corresponding to a domain of 2T is converted to (1,0,1), and (0,0) is converted to (0,1,0) in the recorded signal. In other words, the first &ldquo;1&rdquo; of (1,1) is converted to unit bits &ldquo;1,0&rdquo; and the first &ldquo;0&rdquo; of (0,0) is converted to unit bits &ldquo;0,1&rdquo;. Similarly, the first &ldquo;1&rdquo; of (1,1,1) corresponding to a domain of 3T is converted to unit bits &ldquo;1,0&rdquo;, and the second &ldquo;1&rdquo; is converted to unit bits &ldquo;1,0&rdquo;. &ldquo;1&rdquo; or &ldquo;0&rdquo; of the final unit bit is not converted but recorded as such. Consequently, a signal can be correctly reproduced by extension ally transferring domains having different domain lengths from a recording layer to a reproducing layer under the same reproducing conditions.

Magnetooptical disk unit capable of recording or reproducing signals having different domain lengths under the same conditions, signal recording method and signal reproducing method

A magneto-optical recording medium has a plane structure in which are alternately arranged a groove having discontinuous regions formed at every 120 &mgr;m, for example, and land having discontinuous regions formed at the same every 120 &mgr;m. The position where the discontinuous region of the groove is formed differs from the position where the discontinuous region of the land is formed. The discontinuous region of the land is provided at a position corresponding to substantially the middle of respective continuous regions of the groove. The discontinuous region of the groove is provided at a position corresponding to substantially the center of the continuous region of the land. The width of the groove and land is approximately 0.4 &mgr;m. Therefore, a synchronizing signal arising from a discontinuous region formed periodically at the groove or land can be output properly even when the width of the groove and land is narrowed.

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Gifu, Japan

Kenichiro Mitani