Abstract: A plate spring is provided on a back surface of a shutter of a cartridge. When the shutter is closed, the plate spring presses a disk in a cartridge case against an inner wall surface of a lower case so that the disk is immovable in the case. When the shutter is open, the plate spring is retracted into a space between an inner surface of the shutter and a surface of an upper case. The disk is supported immovably and uniformly in the cartridge. Therefore, deformation such as warpage of the disk hardly occurs. Even when the cartridge is stored in any posture, it is possible to avoid deformation such as warpage and flexure of the disk in the cartridge during the storage.

Abstract: A magneto-optic recording medium includes a second auxiliary magnetic film, a first auxiliary magnetic film and a magneto-optic recording film on a substrate. The auxiliary magnetic films change from in-plane magnetization to vertical magnetization at critical temperatures TCR1 and TCR2. Since they have the relation TCR1>TCR2, the magnetic domain transferred from the magneto-optic recording film to the first auxiliary magnetic film at the time of reproduction is expanded in diameter and is transferred to the second auxiliary magnetic film when the temperature profiles of the auxiliary magnetic films inside an optical spot are utilized. The magnetic domain of the magneto-optic recording film can be expanded and transferred, too, by means of magnetostatic coupling by using a non-magnetic film in place of the first auxiliary magnetic film. Pulse reproduction light subjected to power modulation in synchronism with a reproduction clock can be used at the time of reproduction.

Abstract: A plate spring is provided on a back surface of a shutter of a cartridge. When the shutter is closed, the plate spring presses a disk in a cartridge case against an inner wall surface of a lower case so that the disk is immovable in the case. When the shutter is open, the plate spring is retracted into a space between an inner surface of the shutter and a surface of an upper case. The disk is supported immovably and uniformly in the cartridge. Therefore, deformation such as warpage of the disk hardly occurs. Even when the cartridge is stored in any posture, it is possible to avoid deformation such as warpage and flexure of the disk in the cartridge during the storage.

Abstract: A magneto-optical recording medium comprises a protective layer having a self-lubricating property formed at an uppermost layer on a side opposite to a substrate wherein a recording or reproducing light beam comes into a side of the protective layer. The thickness and the refractive index of the protective layer are selected under predetermined conditions depending on whether or not evanescent light is transmitted through the protective layer. It is possible to perform high density recording and reproduction thereof by utilizing the evanescent light. A protective layer having a self-lubricating property may be also formed on a bottom surface of an optical head opposing to the optical recording medium. Even when the optical head contacts with the surface of the optical recording medium, the sliding scratch scarcely occurs, because the optical head smoothly glides on the recording medium surface.

Abstract: A plate spring is provided on a back surface of a shutter of a cartridge. When the shutter is closed, the plate spring presses a disk in a cartridge case against an inner wall surface of a lower case so that the disk is immovable in the case. When the shutter is open, the plate spring is retracted into a space between an inner surface of the shutter and a surface of an upper case. The disk is supported immovably and uniformly in the cartridge. Therefore, deformation such as warpage of the disk hardly occurs. Even when the cartridge is stored in any posture, it is possible to avoid deformation such as warpage and flexure of the disk in the cartridge during the storage.

Abstract: A magneto-optic recording medium includes a second auxiliary magnetic film, a first auxiliary magnetic film and a magneto-optic recording film on a substrate. The auxiliary magnetic films change from in-plane magnetization to vertical magnetization at critical temperatures TCR1 and TCR2. Since they have the relation TCR1>TCR2, the magnetic domain transferred from the magneto-optic recording film to the first auxiliary magnetic film at the time of reproduction is expanded in diameter and is transferred to the second auxiliary magnetic film when the temperature profiles of the auxiliary magnetic films inside an optical spot are utilized. The magnetic domain of the magneto-optic recording film can be expanded and transferred, too, by means of magnetostatic coupling by using a non-magnetic film in place of the first auxiliary magnetic film. Pulse reproduction light subjected to power modulation in synchronism with a reproduction clock can be used at the time of reproduction.

Abstract: On a surface of a transparent substrate 1 having a preformat pattern 2 formed thereon are laminated a first recording layer 4 in which a recording state exists in one different magnetic field region of an applied external magnetic field and a second recording layer 6 in which two recording states exist in magnetic field regions different from that for the first recording layer. As required, dielectric layers 3, 5 and 7, a reflecting layer 8 and a protection layer 9 can be laminated. The 4-valued recording of information becomes possible by assigning information signals “1”, “0”, “3”, and “2” to H0, H1, H2 and H3, respectively.

Abstract: A magneto-optic recording medium includes a second auxiliary magnetic film, a first auxiliary magnetic film and a magneto-optic recording film on a substrate. The auxiliary magnetic films change from in-plane magnetization to vertical magnetization at critical temperatures TCR1 and TCR2. Since they have the relation TCR1>TCR2, the magnetic domain transferred from the magneto-optic recording film to the first auxiliary magnetic film at the time of reproduction is expanded in diameter and is transferred to the second auxiliary magnetic film when the temperature profiles of the auxiliary magnetic films inside an optical spot are utilized. The magnetic domain of the magneto-optic recording film can be expanded and transferred, too, by means of magnetostatic coupling by using a non-magnetic film in place of the first auxiliary magnetic film. Pulse reproduction light subjected to power modulation in synchronism with a reproduction clock can be used at the time of reproduction.

Abstract: A magneto-optical recording medium comprises a protective layer having a self-lubricating property formed at an uppermost layer on a side opposite to a substrate wherein a recording or reproducing light beam comes into a side of the protective layer. The thickness and the refractive index of the protective layer are selected under predetermined conditions depending on whether or not evanescent light is transmitted through the protective layer. It is possible to perform high density recording and reproduction thereof by utilizing the evanescent light. A protective layer having a self-lubricating property may be also formed on a bottom surface of an optical head opposing to the optical recording medium. Even when the optical head contacts with the surface of the optical recording medium, the sliding scratch scarcely occurs, because the optical head smoothly glides on the recording medium surface.

Abstract: An optomagnetic recording and reproducing system has been developed which demonstrates superior performance when used with multilayer recording substrates. The system features an optical head and magnetic head disposed opposite to each other on different sides of the recording substrate. The novel magnetic head can either incorporate a number of independently driven subheads, or alternately it can be constructed by placing multiple independently driven windings on a single head. Biasing of the magnetic head can either be performed externally using an external magnet or by providing a bias with one of the windings or sub-heads. The resulting optomagnetic recording and reproducing system is suitable for multi-valued recording of an optomagnetic recording medium.

Abstract: On a surface of a transparent substrate 1 having a preformat pattern 2 formed thereon are laminated a first recording layer 4 in which a recording state exists in one different magnetic field region of an applied external magnetic field and a second recording layer 6 in which two recording states exist in magnetic field regions different from that for the first recording layer. As required, dielectric layers 3, 5 and 7, a reflecting layer 8 and a protection layer 9 can be laminated. The 4-valued recording of information becomes possible by assigning information signals "1", "0", "3" and "2" to H.sub.0, H.sub.1, H.sub.2 and H.sub.3, respectively.

Abstract: A magneto-optical recording medium having a thin film, with suitable thermal conductivity, laminated on a magneto-optical film having excellent durability to repeated recording, reproducing and erasing comprising one layer or a multi-layer of thin film containing at least a magneto-optical recording film and carried on a transparent substrate, a ferromagnetic reflection film having a reflectance to a reproduction beam of 70% or higher and a thermal conductivity at a normal temperature from 0.05 to 2.0 W/cm.deg laminated on the backside of the magneto-optical recording film viewed from the transparent substrate side and, optionally, a heat control layer having a thermal conductivity at a normal temperature of 0.1 to 2.0 W/cm.deg laminated on the backside of the magneto-optical film.

Abstract: Disclosed is a magneto-optical recording medium which comprises a transparent substrate and, provided on the substrate, a magneto-optical recording film comprising a perpendicular magnetic film based on rare earth metal-transition metal and an auxiliary magnetic film having spontaneous magnetization which exerts, between itself and the magneto-optical recording film, an exchange coupling force on each other and in which the auxiliary magnetic film used is a magnetic film which readily rotates its magnetization direction toward the external magnetic field in the neighborhood of the Curie temperature of the magneto-optical recording film and has a squareness ratio of not more than 1 in the neighborhood of the Curie temperature, and a process for producing the magneto-optical recording medium.

Abstract: A magneto-optical recording medium having a thin film with a suitable thermal conductivity, laminated on magneto-optical film, having excellent durability to repeated recording, reproducing and erasing comprising one layer or a multi-layer of thin film containing at least a magneto-optical recording film carried on a transparent substrate, a ferromagnetic reflection film having a reflectance to a reproduction beam of 70% or higher and a thermal conductivity at a normal temperature from 0.05 to 2.0 W/cm.deg laminated on the backside of the magneto-optical recording film viewed from the transparent substrate side and, optionally, a heat control layer having a thermal conductivity at a normal temperature of 0.1 to 2.0 W/cm.deg may be laminated on the backside of the magneto-optical film.

Abstract: Disclosed is a magneto-optical recording medium which comprises a transparent substrate and, provided on the substrate, a magneto-optical recording film comprising a perpendicular magnetic film based on rare earth metal-transition metal and an auxiliary magnetic film having spontaneous magnetization which exerts, between itself and the magneto-optical recording film, an exchange coupling force and wherein the auxiliary magnetic film is a magnetic film which readily rotates its magnetization direction toward the external magnetic field in the neighborhood of the Curie temperature of the magneto-optical recording film and has a squareness ratio of not more than 1 in the neighborhood of the Curie temperature. Also disclosed is a process for producing the magneto-optical recording medium.