Abstract: A magnetic recording medium having a magnetic layer includes a plurality of tracks formed on the magnetic layer. The tracks have information magnetically recorded thereon. A magnetization change area for tracking control is formed on the magnetic layer adjacent to and along a length of each of the tracks. The magnetization change area has magnetic flux which changes along the length of the tracks.

Abstract: The magnetic recording and reproducing apparatus reads a transfer clock synchronized with servo information and records a write-once clock pattern in a state where 0 is set as a delay time of the delay device 13 and 1 is set as the dividing ratio of the frequency divider 17. The apparatus corrects the delay time according to the output of the phase comparator 14 which changes on the basis of the phase difference and rewrites a write-once clock pattern. Rotation of the magnetic disk, detection of the phase difference and correction of the delay time are repeatedly preformed until no change occurs in the output of the phase comparator 14. After the output stops changing, preformat information patterns excluding the servo information pattern are recorded as fine patterns by changing the dividing ratio of the frequency divider 17 to multiply the frequency.

Abstract: The present invention provides an optical disk comprising: at least a rewritable region and a read-only data region, wherein the rewritable region includes a plurality of groove tracks and a plurality of land tracks, the read-only data region includes a plurality of groove tracks and a plurality of land tracks, read-only data comprising control data are written as concavo-convex pits to the groove tracks and/or the land tracks in the read-only data region, and the width of each groove in the read-only data region is smaller than that of each groove in the rewritable region. According to the first optical disk of the present invention, the area of rewritable regions for users can be ensured as broadly as possible failing to deteriorate the high-speed performance of the system.

Abstract: The present invention provides a magnetic recording unit, including: a magnetic head; a magnetic recording medium having a servo pattern for adjusting a position of the magnetic head; a frequency detecting element for detecting a frequency in the servo pattern on a track corresponding to the position in a radial direction of the magnetic recording medium, on the basis of a reproduction signal obtained by reading the servo pattern with the magnetic head; a storage element for storing in advance information on predetermined frequencies corresponding to the positions of tracks of the magnetic recording medium; a tracking element for comparing the frequency detected on the track by the frequency detection element and the information on the frequency corresponding to the same track, the information being stored in the storage element, and for generating a signal for adjusting the position of the magnetic head, the signal being generated on the basis of a difference between the frequencies.

Abstract: An optical recording medium driving apparatus which can obtain a tracking error signal necessary for an accurate track count. An optical recording medium driving apparatus for recording and/or reproducing data in/from an optical recording medium, where information can be recorded in plural tracks formed by land portions and groove portions provided between the land portions, based on a light emitted to the tracks. The apparatus includes a detector for detecting a position of the emitted light, a peak-hold circuit for holding a peak of a position detected signal outputted from the detector so as to output the position detected signal, a bottom-hold circuit for holding a bottom of the position detected signal so as to output the position detected signal, and a switching circuit for switching signals based on the output signals from the peak-hold circuit and bottom-hold circuit so as to output either signal.

Abstract: A master medium for magnetic transfer includes a substrate having a concave portion formed in its surface corresponding to a pattern of recorded information to be transferred; a first perpendicular ferromagnetic layer deposited in the concave portion; and a second perpendicular ferromagnetic layer layered on the substrate surface and the first perpendicular ferromagnetic layer surface. The substrate surface and the first perpendicular ferromagnetic layer surface are flattened to form a single flat surface. In the master medium for magnetic transfer, a magnetic field change in a direction parallel to the substrate surface at a magnetization boundary of the first perpendicular ferromagnetic layer is steep. Since the influence of the change of an external magnetic field is reduced, it is possible to perform accurate transfer from the master medium for magnetic transfer to a slave medium for magnetic recording.

Abstract: In a method of manufacturing a mold for forming an information pattern including servo information or address information on a substrate of a recording medium by being pressed onto the heated substrate, carbon is used as a material for the mold. A mask corresponding to the information pattern is formed on the mold made from carbon of the present invention. Said carbon plate is etched in areas having no mask formed thereon, and lastly the mask is removed.

Abstract: A magneto-optical recording medium capable of perfectly masking a mark adjacent to a mark to be reproduced thereby improvng reproduction output. The magneto-optical recording medium includes a transparent substrate, a magnetic reproducing layer laminated on the transparent substrate, a nonmagnetic intermediate layer laminated on the magnetic reproducing layer, and a magnetic recording layer laminated on the nonmagnetic intermediate layer. The reproducing layer has an easy direction of magnetization in a plane at room temperature, and has an easy direction of magnetization perpendicular to a film surface at a given temperature or higher. The nonmagnetic intermediate layer is thin enough to allow magnetostatic bond between the recording layer and the reproducing layer at the given temperature or higher.

Abstract: A magneto-optical recording medium capable of perfectly masking a mark adjacent to a mark to be reproduced thereby improving a reproduction output. The magneto-optical recording medium includes a transparent substrate, a magnetic reproducing layer laminated on the transparent substrate, a nonmagnetic intermediate layer laminated on the magnetic reproducing layer, and a magnetic recording layer laminated on the nonmagnetic intermediate layer. The reproducing layer has an easy direction of magnetization in a plane at room temperature, and has an easy direction of magnetization perpendicular to a film surface at a given temperature or higher. The nonmagnetic intermediate layer is thin enough to allow magnetostatic bond between the recording layer and the reproducing layer at the given temperature or higher.

Abstract: A magneto-optical recording medium capable of perfectly masking a mark adjacent to a mark to be reproduced to thereby improve a reproduction output. The magneto-optical recording medium includes a transparent substrate, a magnetic reproducing layer laminated on the transparent substrate, a nonmagnetic intermediate layer laminated on the magnetic reproducing layer, and a magnetic recording layer laminated on the nonmagnetic intermediate layer. The reproducing layer has an easy direction of magnetization in a plane at room temperature, and has an easy direction of magnetization perpendicular to a film surface at a given temperature or higher. The nonmagnetic intermediate layer is thin enough to allow magnetostatic bond between the recording layer and the reproducing layer at the given temperature or higher.

Abstract: An optical recording medium in which information can be recorded in tracks formed by both lands and grooves provided between lands, and rows of prepits corresponding to preformat information in both adjacent lands and grooves are formed by deviating in the circumferential direction. Counting grooves for counting tracks are formed at both sides of the row of prepits for the land, the prepit for the groove has a depth or width different from that of the groove, the counting groove has a depth or width different from that of the groove, and the prepit for the land is formed narrower and/or shallower than the counting groove.

Abstract: A magneto-optic disk has a readout layer formed of a bismuth-substituted garnet having a chemical composition represented by Bi.sub.x R.sub.3-x M.sub.y Fe.sub.5-y O.sub.12 and a recording layer formed of a nonbismuth-substituted garnet having a chemical composition represented by R.sub.3 M, Fe.sub.5-z O.sub.12 (where 0.ltoreq.x.ltoreq.3, 0.ltoreq.y<2, 0.ltoreq.z<2, R represents yttrium or a rare earth element, and M represents element which can be substituted for iron (Fe). The readout layer has a smaller coercive force and a higher Curie temperature in comparison with the recording layer, and exhibits a characteristic of a large angle of Faraday rotation 200 times that of the recording layer with respect to a short-wavelength laser beam of about 500 nm.

Abstract: A magneto-optical recording medium having a recording layer made of a bismuth-substituted garnet and deposited by a sputtering over an amorphous substrate of aluminosilicate or borosilicate glass, the recording medium including a garnet underlayer of either a double-layer or single-layer structure. The formation of an underlayer of a double-layer structure made of garnet reduces the level of noise due to light scattering at crystalline boundaries in the garnet film. The formation of an underlayer of a single-layer structure made of a garnet having a lower crystallization temperature than a YIG film is also effective to noise-level reduction. An underlayer has a surface smoothness corresponding to a roughness of approximately 10 .ANG., which is improved from the surface smoothness of a conventional underlayer comprising a YIG film.