Abstract: A magnetic disk device having a floating-type magnetic head, for use with a disk-shaped recording medium having a sliding area for the floating-type magnetic head formed outside a recording area. The length in the disk radial direction of a suspension supporting the floating-type magnetic head is varied depending on individual magnetic disk devices. In another arrangement, a control means is provided for setting two reference values so that a radial position of the floating-type magnetic head detected by a detection section is compared with these reference values, and for alternating one of the preset reference values to the other reference value upon receiving a rotation stop signal. In still another arrangement, control means is provided, whereby a radial position for sliding of the floating-type magnetic head is randomly varied within the sliding area.

Abstract: A magneto-optical recording medium is consisted of a recording layer, a readout layer and a writing layer. The readout layer is made of rare earth-transition metal alloys wherein an easy magnetization axis is parallel to the recording layer at room temperature, and the easy magnetization axis is perpendicular to the recording layer as the temperature of the readout layer is raised above a predetermined temperature by irradiating thereon with a light beam. The writing layer is made of rare earth-transition metal alloys having such coercive force that a magnetization direction thereof is switched by an external magnetic field at room temperature and Curie temperature that is above Curie temperature of the recording layer.

Abstract: A recording and reading method and device of magneto-optical memory elements are provided to record and read an information signal to and from the magneto-optical memory elements, which contain at least two magnetic layers that are magnetically coupled, by means of a light-intensity modulated overwriting method employing a recording magnetic field and an initializing magnetic field. A control feature is included for applying the initializing magnetic field to the magneto-optical memory elements at least one time between the point of time when moving the magneto-optical memory elements to a recording or reading position, finishing a reading or recording, and ascertaining the selected operation such as recording or erasing and the point of time when subsequent recording begins such that the initializing magnetic field is not applied at the same time as the recording magnetic field.

Abstract: A magneto-optical disk according to the present invention has a substrate (12), a recording layer (13) formed on the substrate and an outer layer (14) 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 (14) 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 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: An optical recording element according to the present invention comprising: (i) a transparent substrate through which light passes; (ii) a transparent low-resistance layer having a specific resistance so as to prevent the adhesion of dust to the surface of the element caused by a static charge, the layer being formed on the surface, on which a light beam is incident, of the transparent substrate; and (iii) an optical thin film composed of at least one layer, formed on the other surface of the transparent substrate so as to transmit light beams used for recording, erasing and playback, and reflect lights which have wavelengths different from the wavelength of the above light beams and are within a specified visible region of the spectrum. With this arrangement, lights within a specified visible region of the spectrum are reflected so that the element appears to be colored according to the wavelengths of the reflected lights.

Abstract: A photomagnetic composite head comprising a magnetic head and an optical head that are integrated into one unit, an optical waveguide path of the optical head being located in the surface of the magnetic head that faces a recording medium, and a laser beam that passes through the optical waveguide path being irradiated on a point on the recording medium where a magnetic field is impressed from the magnetic head, whereby recording can be performed under a condition in which the coercivity of the recording medium has been lowered by the laser beam, thus making it possible to achieve high density recording by using a recording medium with a high coercivity.

Abstract: A magneto-optical disk is provided with a transparent substrate of a disk shape, and a multiple layered structure which is formed on the substrate and includes a plurality of transparent dielectric films and magnetic recording films which are alternatively layered. One method of reproducing the magneto-optical disk is enabled, which has the steps of inputting a circularly or elliptically polarized light on the magneto-optical disk, and detecting an intensity change of the light caused by the magneto-optical disk due to the circular dichroism effect thereof, as a reproduced signal. Another method of reproducing the magneto-optical disk is also enabled, which has the steps of inputting a linearly polarized light on the magneto-optical disk, and detecting a rotation change of a polarization plane of the light caused by the magneto-optical disk due to the magnetic Kerr effect, as a reproduced signal.

Abstract: A recording and reading method and device of magneto-optical memory elements are provided to record and read an information signal to and from the magneto-optical memory elements, which contain at least two magnetic layers that are magnetically coupled, by means of a light-intensity modulated overwriting method employing a recording magnetic field and an initializing magnetic field feature is included for applying the initializing magnetic field to the magneto-optical memory elements at least one time between the point of time when moving the magneto-optical memory elements to a recording or reading position, finishing a reading or recording, and ascertaining the selected operation such as recording or erasing and the point of time when subsequent recording begins such that the initializing magnetic field is not applied at the same time as the recording magnetic field.

Abstract: An apparatus for manufacturing an optical memory device, which includes supplying rolls for continuously supplying a sheet-like substrate, a masking endless belt having a plurality of windows of size corresponding to the optical memory device, rolls for moving the sheet-like substrate and the masking endless belt in the same direction and at the same speed, a recording portion forming device for forming recording portions on the substrate through the masking endless belt, a guide track providing device for providing along the substrate guide tracks for guiding a light beam, and a cutting device for cutting the substrate to a predetermined size.

Abstract: A floating type magnetic head device of the present invention includes a slider capable of floating above a recording medium while moving relatively to the recording medium, and a magnetic head. The magnetic head is incorporated inside a cavity section formed substantially in the center of the slider. By incorporating the magnetic head inside the cavity section, the magnetic head can be protected, thereby reducing a possibility of head crash of the magnetic head due to its contact with dust or a projecting object existing on the surface of the recording medium. Further, by disposing the magnetic head substantially in the center of the slider, it can be avoided that the direction of an air stream at the center of the slider varies depending on an instantaneous position in a radial direction of the recording medium, thereby providing stable floating characteristics of the floating type magnetic head device and improving accuracy of recording.

Abstract: An optical card including an optical storage medium and a single or a plurality of members made of a magnetic material which are incorporated with the optical card is set forth. A card holder for holding the optical card consists of a table for supporting the optical card and a single member or a plurality of members made of a magnetic material for attracting the optical card. An apparatus for recording and reproducing information on and from the optical card held by the card holder includes a light-irradiating unit for emitting light beams onto the optical storage medium of the optical card and a drive unit for relatively moving the card holder and the light-irradiating unit for tracking, with which the recording, reproducing, or erasing operation can be accurately carried out.

Abstract: A floating type magnetic head for magneto-optical recording, the magnetic head being positioned opposite to an optical head with a magneto-optical recording medium inserted therebetween. The magnetic head is supported out of contact with the magneto-optical recording medium and includes a slider and a head core. The head core has an end section located parallel to the magneto-optical medium. The end section is formed to be longer in the direction orthogonal to the tracks contained on the medium than in the direction parallel to the tracks.

Abstract: A magneto-optic memory medium of an exchange-coupled ferrimagnetic double-layered structure having a recording film of a specific amorphous GdTbFe alloy and a reading film of a specific amorphous GdNdFe alloy.

Abstract: The present invention provides a process for manufacturing a magneto-optic disc comprising at least a transparent substrate, a magneto-optic recording film, and a protecting film made of resin for protecting the magneto-optic recording film, comprising the steps of forming the magneto-optic recording film over the entire one side surface of the transparent substrate; providing in a portion adjacent to the peripheral edge of the magneto-optic recording film an annular groove extending in depth through the magneto-optic recording film to the transparent substrate; and forming the protecting film over the surfaces of the magneto-optic recording film and the annular groove.

Abstract: A magneto-optical recording and reproducing device for recording and reproducing data determined by negative magnetized areas in a magneto-optical recording medium. The device including a laser beam output level control means for controlling the intensity of a laser beam when recording data on the medium. The device prevents the causes of false signals and incorrect detection influenced by residual negative magnetized domains by increasing laser beam intensity when rewriting positive magnetized areas to erase residual negative magnetized areas.

Abstract: An apparatus for manufacturing an optical memory device, which comprises supplying rolls for continuously supplying a sheet-like substrate, a masking endless belt having a plurality of windows of size corresponding to the optical memory device, rolls for moving the sheet-like substrate and the masking endless belt in the same direction and at the same speed, a recording portion forming device for forming recording portions on the substrate through the masking endless belt, a guide truck providing device for providing along the substrate guide trucks for guiding a light beam, and a cutting device for cutting the substrate to a predetermined size.

Abstract: A magneto-optical recording/reproducing device having a slider provided with a magnetic head. The slider floats over a magneto-optical disk when the magneto-optical disk is in rotation. The slider is supported by a suspension. A depressing force is exerted on the slider vertically by the suspension. The depressing force is adjusted by an adjustment device so that the depressing force due to the suspension increases as the slider shifts to an outer part of the magneto-optical disk from an inner part. Thus a floating gap between the slider and the magneto-optical disk becomes substantially constant irrespective of a radial position on the magneto-optical disk and a magnetic field intensity applied onto the magneto-optical disk from the slider (the magnetic head) becomes constant. As a result, stable recordomg, reproducing and erasing operations can be carried out.

Abstract: An optical recording medium, which is used as an optical disc, optical card or the like for optically recording, reproducing, erasing and the like, includes a center substrate having formed on at least one side thereof recesses and/or protrusions. Recording films are formed on both sides thereof and transparent protective plates bonded to these recording films respectively. This arrangement substantially eliminates warping of the substrates constituting the optical recording medium and exfoliation of substrates or the like even when the optical recording medium is subjected to sudden changes in temperature. This optical recording medium demonstrates enhanced optical performance and protective effect. The selecting of the transparent protective plate is simplified because the forming recesses and/or protrusions is not a factor. By producing an optical recording medium utilizing the above features, the carrier-to-noise ratio and isotropy of the medium is improved.

Abstract: A magneto-optical memory element has a multi-layer construction in the order from a side first receiving light from a light-source which includes a first transparent dielectric film, a rare earth transition metal alloy film, a second transparent dielectric film and a reflective film. The magneto-optical device uses circular dichroism effect of a magnetic mater for reading information. The rare earth transition metal alloy film has a refractive index represented by n.+-..DELTA.n wherein n=3.2-3.55i and .DELTA.n=0.05-0.03i. The thickness of film is about 18 to 46 nm. The second transparent dielectric film has a refractive index of 2.0.+-.0.2 and a film thickness of 80 to 108 nm.