Fujitsu Corporation

Seiya Ogawa

Yasunobu Hashimoto

Miyozo Maeda

Ken-ichi Itoh

Shigeru Fukushima

Jun Takahashi

Yuji Inouye

Toshikatu Narumi

Kazuo Nakashima

Nagaaki Koshino

Yasuyuki Goto

Koichi Ogawa

Mitsumasa Oshiki

Kazuo Ogasa

Hironori Goto

Ken-ich Itoh

A magnetic recording method using a magnetic head to record information in an information recording medium and read the information recorded on the information recording medium is such that the temperature of a portion of the information recording medium on or from which information is recorded or read is changed in order to record or read information. A disk device having the ability to record and read information comprises a magnetic head for recording information by applying a given magnetic field to an information recording medium and reading the information from the information recording medium; and a temperature changing mechanism for changing the temperature of a portion of the information recording medium on or from which information is recorded or read. The magnetic head is moved to the portion of the medium in which a temperature change is produced by the temperature changing mechanism, whereby information is recorded or read.

Method for using heat to record on magnetic medium and disk apparatus having temperature changing device

A method for overwriting information in a magneto-optical memory medium which includes a simultaneous writing and erasing step of continuously irradiating a written information-carrying area of the recording layer of the memory medium with two different pulses from a single laser beam head in accordance with information to be written, regardless of the presence or absence of written information. A variation includes irradiating the written information-carrying area with an erasing pulse from a laser beam head, regardless of the presence or absence of written information, and then selectively irradiating the information-erased area with a writing pulse from another laser beam head in accordance with information to be written. According to these methods, it becomes possible to carry out a simple and high-speed overwriting with an increased and stabilized bit positioning accuracy.

Magneto optical overwriting methods using a single optical head designed

An optical disk provided with read-exclusive regions where previously recorded information can be read, and with write-enable regions where information can be written. Information not desired to be rewritten can be recorded on the read-exclusive regions. The write-enable regions are open to users to freely add information thereto and to re-write information recorded. This optical disk can thus be used in various fields.

Optical disk having read-exclusive and write-enable regions

A method of overwriting information in a magneto-optical memory medium which includes a simultaneous writing and erasing step of continuously irradiating a written information-carrying area of the recording layer of the memory medium with two different pulses from a single laser beam head in accordance with information to be written, regardless of the presence or absence of written information. A variation includes irradiating the written information-carrying area with an erasing pulse from a laser beam head, regardless of the presence or absence of written information, and the then selectively irradiating the information-erased area with a writing pulse from another laser beam head in accordance with information to be written. According to these methods, it becomes possible to carry out a simple and high-speed overwriting with an increased and stabilized bit positioning accuracy.

Magneto-optical overwriting methods using erasing pulses, each of which

A longitudinal magnetic coated recording medium includes at least planar magnetic particles, each having an easy magnetization axis perpendicular to the planar surface thereof, preferably mixed with other particles, and dispersed in a magnetic film formed on a nonmagnetic substrate, having a orientation angle of -30.degree. to +30.degree.. A process for producing such a recording medium includes the step of orienting the planar magnetic particles by applying a magnetic field approximately in parallel to the surface of the magnetic film.

Longitudinal magnetic coated recording medium

A longitudinal magnetic coated recording medium comprises at least plane magnetic particles each having an easy magnetization axis perpendicular to the major surface thereof, preferably mixed with other particles, and dispersed in a magnetic film formed on a nonmagnetic substrate, having a orientation angle of -30.degree. to +30.degree.. A process for producing such a recording medium comprises the step of orienting the plane magnetic particles by applying at least a magnetic field approximately in parallel to the surface of the magnetic film.

A recording medium suitable for writing and reading out information by irradiating a photobeam onto a recording layer at a relatively low power, includes a light transmissible substrate, a light transmissible subbing layer, and a recording layer. The recording layer includes a radiation transmissible substrate, a radiation transmissible subbing layer composed of an inorganic material laminated on the substrate, and a recording layer composed of a sublimable organic substance layer laminated on the subbing layer and a metal layer laminated on the organic layer. Alternatively, the recording layer can include a radiation transmissible substrate, a radiation transmissible subbing layer composed of an inorganic material laminated on the substrate, and a recording layer the composed of a first metal layer laminated on the subbing layer, a sublimable organic substance layer laminated on the first metal layer, and a second metal layer laminated on the sublimable organic substance layer the recording medium has a high photosensitivity and can record information at a high quality (i.e., a high signal-to-noise ratio).

Recording media with recording layer of two metal layers sandwiching

A magnetic recording medium having finely divided magnetic metal oxide particles dispersed in a thermosetting resin binder and a thickness of no greater than 5 microns is provided. The thermosetting resin binder comprises: (a) 30 to 95 wt.% of a copolymer of 25 to 65 wt.% of alkyl acrylate or alkyl methacrylate, 3 to 30 wt.% of N-methylolacrylamide or N-alkoxymethylacrylamide and 10 to 60 wt.% of styrene or a methyl styrene, (b) 5 to 70 wt.% of an epoxy resin predominantly comprised of a condensation product of bisphenol A and epihalohydrin, and; (c) 0 to 50 wt.% of phenolic resin or amino resin. The magnetic recording medium is superior in abrasion resistance, solvent resistance and dispersion of the magnetic material therein, and possesses improved recording density.

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Kawasaki, Japan

Seiya Ogawa