Fujitsu Corporation

Other

Sony Corporation

Takehiko Numata

Atsushi Takeuchi

Mineo Moribe

Yoshihito Fukushima

Kenichi Itoh

Hiroyuki Takemoto

Shigenori Yanagi

Miyozo Maeda

Teruji Yamakawa

Yoshiyuki Nanba

Teruo Chiba

Nobuyuki Nankumo

Kiyomi Ogino

A magneto-optical recording medium device of the present invention optimizes a magnetic field forming the front mask and a magnetic field forming the rear mask by use of a single bias magnetic field generator, by shifting the peak position of the bias magnetic field in the magneto-optical recording medium device so as to deviate from the center of the laser beam spot in a tangential direction of the magneto-optical recording medium, enabling extended recording and reproduction margins.

Magneto-optical recording medium device

A magneto-optical disk having recording tracks are formed along concentric grooves or a spiral groove. A non-groove region where no grooves are made is provided in a middle part of each recording track. In the non-groove region, there is formed a pit pattern representing information about the recording track. A track-counting U-groove is formed in the non-groove region, for detecting that the light spot of a reading laser beam has moved across the recording track. With the disk thus structured, it is possible to record information at high density and to access a desired recording track at high speed.

Optical recording medium

In a rewritable optical recording medium, a recording surface is divided into a plurality of zones by setting pitch intervals in the radial direction to be constant and a data area and a spare area for a defective sector are allocated in each zone. As for a capacity of the spare area in each zone, a predetermined total capacity of spare areas is allocated so that a spare ratio K&equals;D /D of a capacity D of the spare areas for a capacity D of the data areas becomes almost the same in the zones.

Spare area with a predetermined capacity for a detective sector allocated in each zone

Using MSR (magnetically induced super-resolution) technology, a read-head field is applied to a magneto-optical recording medium when reading an information signal from a recording layer of a magneto-optical recording medium, in order to magnetize the read light-irradiated magnetic layer in one direction in a part of an area within the read light spot. The magneto-optical recording medium using MSR technology adopts the on-land recording method in which an information signal is written to the land, which enables read of an information signal by the MSR technology with a smaller read-head field.

Magneto-optical recording medium, and magneto-optical recording/reproducing apparatus

A storage unit optically reproduces information from an optical recording medium of a type having a control region which is prerecorded with control information with an embossed shape and a data region in which data is recorded optically. The control information includes medium information peculiar to the recording medium, and the control region and the data region have mutually different recording densities. The storage unit is provided with a control device for switching a frequency of a read clock which is used when reproducing the control information and the data from the optical recording medium between a case where the control information is reproduced and a case where the data is reproduced.

Storage unit, optical recording medium and information recording method

On the assumption that a phase difference caused by a birefringence at the substrate is &phgr;,while a one caused by the magneto-optic Kerr effect of the recording layer is &phgr;,, the magneto-optical recording medium formatted to record information in the groove meets the conditions: &minus;20&deg;<&phgr;,<&plus;10&deg; and &minus;45&deg;<(&phgr;,&plus;&phgr;,)<&plus;15&deg;, the magneto-optical recording medium formatted to record information on the land meets the conditions: &minus;20&deg;<&phgr;,<&plus;10&deg; and &minus;15&deg;<(&phgr;,&plus;&phgr;,)<&plus;45&deg;, and the magneto-optical recording medium formatted to record information at both the land and groove meets the conditions: &minus;20&deg;<&phgr;,<&plus;10&deg; and &minus;15&deg;<(&phgr;,&plus;&phgr;,)<&plus;15&deg;.

Magneto-optical recording medium

A magneto-optical recording system which is compatible the write-after-erase magneto-optical media and the directly-over-write magneto-optical media. The magneto-optical recording system provided by the present invention includes a detector used for detecting the type of the medium and a controller coupled to the detector and controlling a write-after-erase operation or a direct-over-write operation with respect to the medium responsive to the medium type.

Magneto-optical disk drive supporting a direct-over-write operation and

Marks are recorded on an optical disk which is rotated at a constant rotational speed by laser light which is converged on a substantially circular spot. The pulse width of a recording pulse is set at a sufficiently narrow value and the recording power of the laser light is maintained at a constant value. Marks (corresponding to '1') are recorded on the entire disk surface by the laser light with the same recording pulse width and with the same recording power. The recording pulse width is less than about 30% of the mark interval obtained when they are recorded on the optical disk at the highest density. The recording power is set at the value which produces the maximum reproduction amplitude when said marks are recorded on the optical disk at the highest density.

Growing community of inventors

Kawasaki, Japan

Takehiko Numata