Sanyo Electric Co., Ltd.

Hiroki Ishida

Hitoshi Noguchi

Atsushi Yamaguchi

Naoyuki Takagi

Kenichiro Mitani

Morio Nakatani

Yoshihisa Suzuki

Sayoko Tanaka

There is provided an optical disk drive capable of appropriately effecting recording and reproducing operations without being affected by offset values and a laser output value, which are set at startup of the disk drive, even when changes have arisen in the internal temperature of the disk drive because of changes in ambient temperature. In an optical disk drive, a temperature sensor provided on a pickup measures a temperature. When changes in temperature are greater than a predetermined level, a focus offset value, a tracking offset value, and a value of laser output from the pickup are reset.

Optical disk drive responsive to internal temperature change

On a dielectric layer of SiN a reproduction layer, a non-magnetic layer of SiN and a recording layer of TbFeCo are formed to provide a magneto optical recording medium. The reproduction layer is formed of a first layer corresponding to a Gd layer, a second layer formed of GdFeCo and a third layer corresponding to a Gd layer. As such, the magneto optical recording medium, with the non-magnetic layer formed in contact with the reproduction layer, can prevent the non-magnetic layer from affecting the reproduction layer and thus prevent the reproduction layer from having a degraded characteristic.

Magneto optical recording medium capable of preventing a reproduction layer from having a degraded characteristic

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

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

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Gifu, Japan

Hiroki Ishida