Abstract: Featured is a recording and reproducing method for recording and reproducing information on and from a recording medium. The medium includes a base having a property that a light can be transmitted therethrough, a readout layer formed on the base, which has an in-plane magnetization at room temperature, whereas, a transition occurs from in-plane magnetization to perpendicular magnetization as temperature rises and a recording layer formed on said readout layer for recording thereon information magneto-optically. A groove for guiding a light beam is formed on a readout layer side of the base and a groove width is set substantially equal to a land width formed between grooves. The recording layer on the grooves and the recording layer on lands are used in recording and reproducing information.

Abstract: A magneto-optical recording medium of the present invention has a recording layer made of a perpendicular magnetization film, and a readout layer which is in an in-plane magnetization state at room temperature and changes into a perpendicular magnetization state with a rise in temperature. When the magneto-optical recording medium is irradiated with a light beam, the readout layer separates into three regions: a region in an in-plane magnetization state, a region in a perpendicular magnetization state, and a region having a temperature not lower than the Curie temperature thereof. Only the region in the perpendicular magnetization state allows copying of the magnetization of the recording layer. Therefore, even when the diameter and intervals of recording bits on the recording layer are very small, it is possible to reproduce a target recording bit separately from a recording bit adjacent to the target recording bit.

Abstract: A magneto-optical recording medium comprising a reproducing magnetic layer having a magnetic layer which is in an in-plane magnetization state at room temperature but shifts to a perpendicular magnetization state as temperature rises, a dielectric layer and a recording magnetic layer having a magnetic layer which exhibits a perpendicular magnetization, sequentially from a photo-receptive side, the recording medium being further comprising a metal layer between the reproducing magnetic layer and the dielectric layer.

Abstract: An optical disk is provided with a recording layer, and with an optical coupling layer on a light-incident side of the recording layer. An optical recording and reproducing device and method include an objective lens and a hemispherical lens, which converge a light beam from a light source and project the light beam onto the optical disk. The hemispherical lens is provided in close proximity to the optical coupling layer, in a position such that an interval therebetween is not more than the wavelength of the light produced by the light source. The light beam converged by the objective lens and the hemispherical lens is coupled with the optical coupling layer while substantially maintaining a direction of propagation in which it was propagating while inside the hemispherical lens.

Abstract: An optical disk has address recording sections each of which has a wobbled part of one of side walls of a groove. Each address recording section is formed by providing convexes of a groove in an adjacent land so as to widen the groove. With the wobbles thus provided in a concavo-convex form, address information is recorded. Besides, the address recording sections thus provided in the grooves are linearly disposed in radial directions of the optical disk. By thus arranging the optical disk on whose grooves and/or lands information is recorded, mixing of wobble frequency components in reproduced information signals does not occur, the sector method is applicable to the optical disk, and information signals of high quality can be obtained.

Abstract: A magneto-optical memory medium according to the present invention comprises a reproducing layer, which has in-plane magnetization at room temperature and perpendicular magnetization when heated to above a predetermined temperature by a reproducing light beam; a recording layer, which is magnetostatically coupled to the reproducing layer; and an in-plane magnetized layer, provided adjacent to the recording layer, which has a Curie temperature at the above-mentioned predetermined temperature. In this medium, at temperatures below the predetermined temperature, signals recorded at high density in the recording layer are masked, and the above-mentioned magnetostatic coupling is suppressed, by magnetic masking by the in-plane magnetized layer.

Abstract: A magneto-optical recording medium is composed of a base which has a property that a light can be transmitted therethrough, a readout layer formed on the base, which has in-plane magnetization at room temperature, whereas, a transition occurs from in-plane magnetization to perpendicular magnetization as the temperature thereof is raised and a recording layer formed on the readout layer for recording information magneto-optically. A recording and reproducing method and the optical head are designed for the magneto-optical recording medium. By the recording and reproducing method using the optical head, information recorded at high density can be reproduced.

Abstract: A magneto-optical recording medium has a recording layer made of a perpendicular magnetization film, and a readout layer which is in an in-plane magnetization state at room temperature and changes into a perpendicular magnetization state with a rise in temperature. When the magneto-optical recording medium is irradiated with a light beam, the readout layer separates into three regions: a region in an in-plane magnetization state, a region in a perpendicular magnetization state, and a region having a temperature not lower than the Curie temperature thereof. Only the region in the perpendicular magnetization state allows copying of the magnetization of the recording layer. Therefore, even when the diameter and intervals of recording bits on the recording layer are very small, it is possible to reproduce a target recording bit separately from a recording bit adjacent to the target recording bit.

Abstract: A magneto-optical memory medium according to the present invention comprises a reproducing layer, which has in-plane magnetization at room temperature and perpendicular magnetization when heated to above a predetermined temperature by a reproducing light beam; a recording layer, which is magnetostatically coupled to the reproducing layer; and an in-plane magnetized layer, provided adjacent to the recording layer, which has a Curie temperature at the above-mentioned predetermined temperature. In this medium, at temperatures below the predetermined temperature, signals recorded at high density in the recording layer are masked, and the above-mentioned magnetostatic coupling is suppressed, by magnetic masking by the in-plane magnetized layer.

Abstract: A magnetic recording medium having a recording layer made up of a ferrimagnetic material whose compensation temperature is included within room temperatures and an information recording-reproduction method using the magnetic recording medium. During recording, while a light beam is projected on the recording layer so as to raise the temperature of a recording portion, information is recorded by applying a signal magnetic field from a magnetic head. During reproduction, while a light beam is projected on a reproducing portion of the recording layer so as to raise the temperature thereof, information is reproduced by detecting leakage flux from the reproducing portion by the magnetic head. Thus, during reproduction, no magnetic flux is generated from other portions of the recording layer not irradiated by the light beam. With the arrangement, crosstalk due to leakage flux from adjoining tracks not irradiated by the optical beam can be eliminated.

Abstract: An optical disk of the present invention includes a transparent dielectric film formed on a light incident side of the disk on an opposite side of an optical recording film so as to sandwich the transparent substrate therebetween, for suppressing bimetallic effects caused by a difference in thermal expansion between an optical recording film formed on an optical recording surface and the transparent substrate, whereby changes in tilt against temperature changes can be suppressed. Further, by an optimal selection of a reflectance of the transparent dielectric film, unwanted reflection due to multi-interference can be reduced at the same time.

Abstract: In an optical disk, grooves and lands serving as recording tracks are provided, the grooves are shaped so as to have virtually the same width, and in a first region, the two side walls of each groove wind in accordance with address information. The first region of the groove is formed with its leading portion located at the same angular position as the leading portion of at least one of the first regions of the adjacent grooves. Moreover, the winding portions corresponding to respective bits of the address information are formed in a manner so as to synchronize to the adjacent grooves. With this arrangement, it becomes possible to easily detect address information from the grooves and lands, and consequently to obtain an information reproducing signal with high quality.

Abstract: An optical disc having a recording film formed on one surface of a plastics substrate transparent to light, a first protection film formed on the recording film, a moisture proof film formed on the other surface of the substrate, and a second protection film formed on the moisture proof film.

Abstract: An optical disk has address recording sections each of which has a wobbled part of one of side walls of a groove. Each address recording section is formed by providing convexes of a groove in an adjacent land so as to widen the groove. With the wobbles thus provided in a concavo-convex form, address information is recorded. Besides, the address recording sections thus provided in the grooves are linearly disposed in radial directions of the optical disk. By thus arranging the optical disk on whose grooves and/or lands information is recorded, mixing of wobble frequency components in reproduced information signals does not occur, the sector method is applicable to the optical disk, and information signals of high quality can be obtained.

Abstract: A magneto-optic memory medium comprising a dielectric film, a magneto-optic memory film, a dielectric film and a reflective film superposed in layers on a light trnasmitting substrate, the magneto-optic memory film being a rare earth-transition metal alloy film having the composition formula of:(Gd.sub.x Tb.sub.1-x).sub.y Fe.sub.1-ywherein x is 0.58 to 0.62, and y is 0.27 to 0.33, which is useful as a magneto-optic disc or magneto-optic card.

Abstract: A magneto-optical recording disk includes a recording layer for recording information as a mark and a reproduction layer, laminated with the recording layer, to which magnetization direction of the recording layer is transferred at high temperatures, wherein the reproduction layer and the recording layer are magnetostatically coupled and are not exchange-coupled. The information is read out by using a temperature distribution generated by a light beam for reproduction. The recording layer has, on a side thereof to which the reproduction layer is not provided, a supplementary back layer of a soft magnetic material composed of ferromagnetic material. The magneto-optical disk is designed to generate good CNR and thereby improves recording density even when a short mark is reproduced.

Abstract: An optical disk substrate in which a winding groove, which is winding in accordance with address information, and a normal groove, which is not winding, are placed alternately in the radial direction as tracking guides used for tracking control. With respect to this optical disk substrate, a laser beam, which is used for forming patterns for the tracking guides, is applied while being switched alternately between the first mode that exerts oscillations in the disk radial direction in accordance with the address information and the second mode that does not exert oscillations. An optical disk has a construction in which at least a recording layer is formed on the optical disk substrate.

Abstract: A magneto-optical recording medium including at least a recording layer, and an auxiliary recording layer which achieves magnetostatic coupling with the recording layer. The auxiliary recording layer is in an in-plane magnetization state at temperatures lower than a recording temperature, and in a perpendicular magnetization state at temperatures not lower than the recording temperature. It is therefore possible to achieve a decrease in a recording magnetic field.

Abstract: A super-resolution magneto-optical recording medium has a reproducing layer, an in-plane magnetization layer and a recording layer. The reproducing layer and the recording layer are magnetostatically coupled, and each of the layers is made of a rare-earth transition-metal alloy which has a greater transition-metal sublattice moment than the compensation composition, and exhibits perpendicular magnetization, if it exists alone. At a temperature not more than the Curie temperature, the in-plane magnetization layer is exchange-coupled with the reproducing layer so as to allow the reproducing layer to exhibit in-plane magnetization. Since the reproducing layer is allowed to exhibit in-plane magnetization by the in-plane magnetization layer, it is not necessary to use a material containing a greater rare-earth metal sublattice moment as the reproducing layer.

Abstract: An optical disk has address recording sections each of which has a wobbled part of one of side walls of a groove. Each address recording section is formed by providing convexes of a groove in an adjacent land so as to widen the groove. With the wobbles thus provided in a concavo-convex form, address information is recorded. Besides, the address recording sections thus provided in the grooves are linearly disposed in radial directions of the optical disk. By thus arranging the optical disk on whose grooves and/or lands information is recorded, mixing of wobble frequency components in reproduced information signals does not occur, the sector method is applicable to the optical disk, and information signals of high quality can be obtained.