Abstract: A magneto-optical recording medium is composed of first through fourth magnetic layers laminated in this order in such a way that an exchange coupling exists between any adjacent layers of the first through fourth magnetic layers so that a magnetization direction can be copied, wherein the first magnetic layer is a memory layer, the second magnetic layer is a writing layer, the third magnetic layer is a switching layer, and the fourth magnetic layer is an initializing layer. Further, respective Curie temperatures Tci satisfy an inequation Tc.sub.3 <Tc.sub.1 <Tc.sub.2, Tc.sub.4 (i=1, 2, 3, or 4 indicating an ordinal number of the magnetic layers); and the second magnetic layer exhibits an in-plane magnetization at room temperature, whereas, exhibits a perpendicular magnetization above a predetermined temperature set between the room temperature and Tc.sub.3 temperature.

Abstract: A magneto-optical recording apparatus of the present invention is provided with an objective lens for focusing a light beam onto a magneto-optical recording medium. A pair of magnets is disposed on opposite sides of the magneto-optical recording medium and apply a writing magnetic field onto a portion of the magneto-optical recording medium that has been irradiated by the light beam while applying an initializing magnetic field greater than the writing magnetic field onto a portion apart from that irradiated by the light beam.

Abstract: A magneto-optical recording medium has a recording layer including two magnetic layers. The magneto-optical recording medium satisfies a condition of .vertline.A.sub.1.K.sub.1 -A.sub.2.K.sub.2 .vertline..ltoreq.0.18 (erg.sup.2 /cm.sup.4) wherein A.sub.1, K.sub.1, A.sub.2, and K.sub.2 respectively represent an exchange constant of a first magnetic layer, a perpendicular magnetic anisotropy of the first magnetic layer, an exchange constant of a second magnetic layer, and a perpendicular magnetic anisotropy of the second magnetic layer. First and Second magnetic layers are made of TbFeCo.

Abstract: A magneto-optical disk, which possesses a disc-shaped substrate and a recording layer composed of a perpendicular magnetization film that is formed on the substrate, characterized in having: an area wherein magnetic domains having an upward magnetization and magnetic domains having a downward magnetization are alternately aligned along at least one circuit of the disk, the area being formed on the recording layer, the length of the magnetic domains having the upward magnetization being virtually equal to the length of the magnetic domains having the downward magnetization. This invention also has a reproducing method which is characterized in that, when information is reproduced by projecting a light beam onto the magneto-optical recording disk, the intensity of the light beam is adjusted so as to maximize the amplitude of a reproduced signal that is obtained from the area.

Abstract: A magneto-optical disk having a magnetic layer and a conductive layer laminated on a transparent substrate, and having a lubricant layer provided on the conductive layer. Recording and reproduction on and from the magneto-optical disk are performed by a flying head. The flying head glides above and lands on the lubricant layer. The magneto-optical disk can therefore be removed from the device easily since a magnetic head does not adhere to a recording medium. Further, a depressing force exerted on the flying head is controlled so as to maintain a constant floating gap between the flying head and the recording medium. The depressing force is controlled by electrostatic capacity between an electrode, provided on a bottom face of the flying head, and the conductive layer. Consequently, highly reliable recordings can be made since a magnetic field intensity applied to the magnetic layer becomes constant.

Abstract: A magneto-optical recording medium has (1) a first magnetic layer made of a magnetic material which is changed into a vertical magnetization film in response to a temperature rise while is an in-plane magnetization film at a room temperature; (2) a second magnetic layer made of a vertical magnetization film; and (3) a third magnetic layer made of a vertical magnetic film having a higher Curie temperature than that of the second magnetic layer; and (4) a base substrate on which the first, second, and third magnetic layers are luminated in this order. With the arrangement, the optically modulated overwriting can be carried out with respect to the second magnetic layer and it is not necessary to complete the magnetization direction to one direction for each optically modulated overwriting. Moreover, it is possible to reproduce through the first magnetic layer the information which is recorded on a smaller portion than a light beam spot.

Abstract: A surface of a magneto-optical recording medium of the present invention is textured with fine and physical protrusions and recessions. The shapes of physical protrusions and recessions vary at each radial locations on the medium such that, for example, rough protrusions and recessions are formed in inner parts of the recording medium and fine protrusions and recessions are formed in outer parts thereof. Therefore, floating force given to a floating head from the medium being rotated based on the constant angular velocity method through an air layer in the outer parts equals floating force in the inner parts. Consequently, since the floating height of the floating head becomes constant irrespective of radial locations on the medium, information can be recorded under constant recording conditions, permitting the accuracy of the recording to improve.

Abstract: A magneto-optical memory device is provided with a recording track having a recording film and a guide track wherein a perpendicular magnetic film, whose magnetization direction is arranged in one direction, is formed, the recording track and the guide track being alternatively disposed. A recording operation is carried out using a circular magnetic field generated from the perpendicular magnetic film by projecting a light beam only on the recording track so as to raise the temperature of the recording film. When erasing, the light beam is projected on the recording track and respective portions of the guide tracks located on both sides of the recording track so as to raise the temperature thereof. As the temperature rises, the magnetization of the perpendicular magnetic film becomes smaller, and an erasing operation is therefore performed using an external magnetic field.

Abstract: A magneto-optical recording method includes the steps of applying an external magnetic field perpendicularly onto the magnetic thin film with perpendicular magnetization of a magneto-optical recording medium and projecting a light beam onto the magneto-optical recording medium; and modulating the intensity of the light beam between the first light intensity and the second light intensity in response to the information to be recorded while shifting a spot of the light beam, thereby recording information. In the above method, the first light intensity is set such that by reducing the coercive force of the magnetic thin film with perpendicular magnetization, a magnetic domain is formed on the magnetic thin film with perpendicular magnetization, and that the magnetic domain is moved as the spot of the light beam is shifted. The second light intensity is set such that by increasing the coercive force of the magnetic thin film with perpendicular magnetization, the magnetic domain is fixed to the position.

Abstract: A magneto-optical recording method for rewriting of information including the steps of projecting a light beam, whose intensity varies in response to information to be recorded, onto a magnetic thin film with perpendicular magnetization while an external magnetic field of a constant intensity is being applied thereto; and arranging the magnetization direction of an area irradiated with the light beam of the magnetic thin film with perpendicular magnetization in the direction of the external magnetic field when projecting the light beam of high intensity, while arranging it in the direction of demagnetizing field, opposite to the direction of the external magnetic field generated by magnetization in the vicinity of the irradiated area when projecting the light beam of low intensity, and a magneto-optical memory element provided with a base whereon the magnetic thin film with perpendicular magnetization and an in-plane magnetization film are formed.

Abstract: A magneto-optical recording device has a flying head that floats over a magneto-optical disk according to the rotation of the magneto-optical disk. The flying head includes a head slider. A solid lubricant is applied to the bottom surface of the head slider facing the magneto-optical disk. Since the solid lubricant makes the flying head contact with the magneto-optical disk smoothly, the scratching and wear of the magneto-optical disk and the flying head decrease. Therefore, the reliability and the durability of the magneto-optical recording device can improve. Physical protrusions and recessions or holes containing fluorocarbon oil therein may be formed instead of the solid lubricant. In this case, the contact area between the flying head and the magneto-optical disk is also smaller than the case where physical protrusions and recessions are not formed.

Abstract: A magneto-optical disk comprising a substrate whereon a recording medium is formed, and a depression is formed on the substrate on the inside of the recording medium of the substrate. A center hub is installed on the depression such that the center hub is substantially level with a protective resin layer covering the recording medium. On the center hub, a flying head performs CSS (Contact Start and Stop). This configuration of the disk eliminates the occurrence of dust due to the abrasion and head crash, and achieves stable CSS. A method of manufacturing the magneto-optical disk, wherein the protective resin layer is formed after installing the center hub on the depression. In this method, since a space is not produced between the center hub and the protective resin layer, the stable flying characteristics is obtained. And a magneto-optical disk whereon small physical bumps and pits are formed on the substrate on the inside of the recording medium, which prevents the flying head from sticking to the disk.

Abstract: A master plate for manufacturing a stamper for injecting molding of an optical memory device has a substrate having a plurality of guiding grooves on a surface thereof with a predetermined interval. The respective edge portions of the guiding grooves are inclined with respect to the surface of the substrate at an angle not more than 30.degree.. According to a manufacturing method of the master plate, the post-baking process is carried out at a baking temperature of not less than 150.degree. C. and an etching gas containing O.sub.2 gas of 4 (SCCM) to 10 (SCCM) is used. Thus, even when the copying is carried out with respect to the substrate of the optical memory device according to the injection molding process wherein the stamper, which is manufactured based on the above-mentioned master plate, is used, the mold release of the stamper can be carried out without being caught by the substrate.

Abstract: An external magnetic field device for a magnetooptical information recording and reproducing apparatus in which an external magnetic field to be applied to a magnetooptical information recording medium is modulated by supplying to a magnetic head an alternate current the polarity of which is changed according to information to be recorded. The device comprises an offset circuit for producing an offset in the alternate current. The direction of the offset is selected so as to increase the current level of the polarity by which the initial magnetization of the information recording medium is reversed. The direction of the offset may be selected so as to cancel the leakage magnetic field.

Abstract: An optical memory device comprising at least one transparent substrate and a light reflection layer or an optical memory layer laminated on one surface of the substrate, in which the light reflection layer or the optical memory layer is constituted with a UV-ray or electron-ray cured resin dispersingly containing a light reflective metal powder or an optical recording material.

Abstract: A magneto-optical disk according to the present invention has a substrate, a recording layer formed on the substrate and an outer layer formed on the recording layer, above which a floating head is hovered. The outer layer is constituted of a protective layer, an antisticking layer for head, having a texture formed on its surface and other layers. The magneto-optical disk is designed such that, when rotated at a constant angular velocity, the thickness of the outer layer is substantially inversely proportional to a radial position r on the magneto-optical disk raised to the 1/2nd power. In the formation of the outer layer, a screen whose meshes become gradually finer from the innermost portion toward the circumferential portion of the magneto-optical disk is employed based on the screen printing technique.

Abstract: A surface of a magneto-optical recording medium of the present invention is textured with fine and physical protrusions and recessions. The shapes of physical protrusions and recessions vary at each radial locations on the medium such that, for example, rough protrusions and recessions are formed in inner parts of the recording medium and fine protrusions and recessions are formed in outer parts thereof. Therefore, floating force given to a floating head from the medium being rotated based on the constant angular velocity method through an air layer in the outer parts equals floating force in the inner parts. Consequently, since the floating height of the floating head becomes constant irrespective of radial locations on the medium, information can be recorded under constant recording conditions, permitting the accuracy of the recording to improve.

Abstract: A magnetic storage device and a manufacturing method thereof, the magnetic storage device having grooves formed on a substrate, each of the grooves having a magnetic film formed therein. Since the magnetic head does not contact directly with the magnetic film, reliability of the magnetic disk increases. Moreover, the reproduced output of the magnetic head increases since the space between the magnetic head and the magnetic disk can be reduced. Accordingly, high-density recording becomes possible.

Abstract: An information reproducing apparatus which has a rotating driver for rotating a disc-shaped recording medium, a floating-type head for reproducing information recorded in the recording medium while floating above the disc-shaped recording medium that is being rotated by the rotating driver, and a suspension, made of an elastic member, for supporting the floating-type head. The information reproducing apparatus is characterized in that the floating-type head has a slider which is floated by an air flow that is directed near the surface of the rotating disc-shaped recording medium, and that the slider has a bevelled portion at one side that faces the outer edge of the disc-shaped recording medium such that any contact between the slider and the ridge that exists along the outer edge area of the disc-shaped recording medium is virtually eliminated.

Abstract: A magneto-optic memory device, such as a magneto-optic disk or magneto-optic card having a pair of opposed substrates at least one of which is transparent. Between the substrates is a magneto-optic memory layer made of a stack of dielectric film, a rear earth-transition metal alloy thin film, a dielectric film and a light reflecting film built on the surface of the transparent substrate opposed to the other substrate. An adhesive layer covers the memory layer and bonds the transparent substrate to the other substrate. Lastly, a metal nitride film interposed between the light reflecting film of the memory layer and the adhesive layer.