Abstract: An optical information recording medium is composed of a substrate and a recording layer, formed thereon, which recording layer causes the reversible phase change by the application of an electromagnetic wave thereto, and comprises a phase-changeable type alloy with the composition of (XYZ.sub.2).sub.1-x M.sub.x, wherein X is an element of the group Ib, Y is an element of the group Va, Z is an element of the group VIa, M is an element selected from the group consisting of Sb, Bi, In, Al and Ga, and 0<x<1.

Abstract: Method and apparatus for recording information on an opto-magnetic recording medium by applying an A.C. magnetic field of a constant frequency to the opto-magnetic recording medium as a recording bias magnetic field and scanning the medium by a light beam modulated with a recording signal in synchronism with the A.C. magnetic field to record the information.

Abstract: A method and an apparatus for MO recording that allow real overwrite by light power modulation with a combination of a storage medium consisting of a single-layer RE-TM film and a single-laser source. The medium has a Curie temperature not less than about 500.degree. C. and has high saturation magnetization around 200.degree. C. The coercive force drops to a level that allows the magnetization to be reversed by the demagnetization field at around 200.degree. C.

Abstract: An apparatus for recording an input signal on a magneto-optical recording medium. The apparatus includes an optical head for applying a light beam to the medium, a circuit for delaying the input signal by a time for preventing a bit recorded on the medium from shifting relative to the input signal, a magnetic head for applying a magnetic field modulated in conformity with the delayed signal to that portion of the medium to which the light beam is applied, and a motor for moving the medium relative to the light beam.

Abstract: An improvement is disclosed relating to optical data storage media having two thermo-optically active layers which absorb light at distinct wavelengths--an expansion layer in which data appear as bulges formed upon the absorption of light, and a retention layer which fixes such bulges in place until it is selectively heated to a rubbery state permitting relaxation of the expansion layer and the consequent disappearance of the bulges. In accordance with the improvement, the retention layer is modified so that it absorbs a controlled amount of light at the wavelength which is absorbed by the expansion layer, with the result that it absorbs light at both wavelengths rather than just one. Direct heating of both layers by light absorption during recordation, and accordingly a faster recordation response, are thus achieved.

Abstract: A magneto-optical head wherein a light flux, which is reflected from a recording medium, is separated into its central portion and remaining portion. The central light flux portion is only used as a magneto-optical signal while the remaining light flux portion is only used as an optical servo signal.

Abstract: In an opto-magnetic disk type writing/reading apparatus having a magnetic head held by a suspension load beam in an air-borne floating state over a surface of the opto-magnetic disk, the suspension load beam is raised up or put down in a manner that firstly the opto-magnetic disk is revolved at a higher revolution speed than the predetermined rated revolution speed for a predetermined short period, and thereafter the revolution speed is lowered to the predetermined revolution speed after soft-landing putting down of the magnetic head to achieve a steady-state air-borne floating position.

Abstract: In an optical head, a light beam is emitted from a semiconductor laser which is rotatably supported and is guided to an optical disk through a beam splitter having a non-polarization beam split surface. The light beam reflected from the optical disk is reflected from the non-polarization beam split surface of the beam splitter, and directed to an photo-detector. The non-polarization beam split surface has reflectances which are determined so that E(1-Rp)Rp/E(1-Rs)Rs falls within a range of 1/2 to 2, where E is a ratio of an intensity of a light beam generated by said light source means to an intensity of a light beam returned to said non-polarization beam split surface, and Rs and Rp are reflectances with respect to the S and P polarized light components.

Abstract: A magneto-optical recording apparatus comprising an optical head shiftable in the diametrical direction of a magneto-optical disk and capable of irradiating a light beam onto the magneto-optical disk, and a magnetic head disposed to be mutually opposite to the optical head with the magneto-optical disk interposed therebetween and capable of applying a magnetic field to the magneto-optical disk while being shifted in the diametrical direction of the magneto-optical disk, wherein the magnetic head is shiftable in the diametrical direction of the magneto-optical disk together with the optical head. The magnetic head consists of an E-shaped core and a coil wound around a center core element thereof, and the E-shaped core is so formed that the sectional length of the center core element in one direction extending toward two side core elements becomes equal to or shorter than the sectional length in another direction orthogonal thereto.

Abstract: A multilayer, direct-overwrite, magnetooptic recording element comprises first and second layers of magnetic materials having different magnetic coercivities and Curie temperatures. According to the invention, one of the two magnetic layers is doped with zirconium. The addition of zirconium has the effect of substantially lowering the Curie temperature of the doped layer, thereby enlarging the Curie temperature differential between the magnetic layers. The zirconium additive also has the effect of stabilizing the magnetic properties of the doped layer.

Abstract: A magneto-optical recording medium having a magnetic film having magnetization normal to a plane thereof and having a number of prepits preformed in an optically detectable form at a predetermined interval along a track is prepared. Areas between the prepits are defined as recording areas in which data is to be recorded. A clock signal having a predetermined frequency is generated in synchronism with a reproduced signal corresponding to the prepits of the magneto-optical record medium in response to the reproduced signal. A radiation pulse having an energy corresponding to a signal having a predetermined pattern is irradiated to the magneto-optical record medium in accordance with the clock signal to record the predetermined pattern in at least one of the recording areas prior to code data to be recorded. A phase difference (.delta..sub.2) between the reproduced signal corresponding to the recorded predetermined pattern and the clock signal is detected and a difference (.delta..sub.1 -.delta..sub.

Abstract: A method and apparatus for recording a signal in a magneto-optical disk having pre-pits formed on a recording track which pits are optically detectable for generation of data read and write clocks. The method and apparatus includes the steps of: prior to writing data in the magnetooptical disk, writing a test pattern on a leading portion of a data recording area of the magnetooptical disk at predetermined timings; reading the data recording area to generate a time shift between the read-out test pattern and the original test pattern; adjusting the predetermined timings in accordance with the time shift to generate adjusted data write timings; and writing data in the data writing area in accordance with the adjusted data write timings and the apparatus therefore.

Abstract: An optical reading and magnetic writing device for data on a magnetooptic recording carrier including a writing transducer (TRI) of data on the carrier disposed on a flying head (PATI), a light source (SLI) emitting a beam of polarized incident light (F.sub.i) onto the surface of the carrier, a holographic lens (LHI) for focusing the incident beam (F.sub.i) onto the surface of the carrier, affixed to the head, a separator element (ESI) separating the incident beam from the reflected beam, and a detector (MDKI) for detecting the angle of rotation of the plane of polarization of the light. According to the invention, the optical reading and magnetic writing device is characterized in that the light source (FLI) is disposed and fixed on the head (PATI). The invention is applicable to magnetooptic disk memories.

Abstract: An optomagnetic disk recording and reproducing apparatus includes an optomagnetic disk having a vertical magnetic film capable of recording and reproducing an information signal, a recording and reproducing head unit for recording an information signal in the optomagnetic disk and reproducing an information signal recorded in the optomagnetic disk, a spindle motor for rotationally driving the optomagnetic disk, and means for controlling the spindle motor such that a rotational speed of the optomagnetic disk upon reproducing of an information signal recorded in the optomagnetic disk performed by the recording and reproducing head unit is set higher than the rotational speed of the optomagnetic disk upon recording of an information signal in the optomagnetic disk performed by the recording and reproducing head unit.

Abstract: Optical information carrier comprising an optical transparent layer and a reflective layer adjacent to each other whereby the interface comprises an optically readable information structure containing alternate areas with such different properties, so that a scanning light beam is modulated in correspondence with the information present in said structure. Between the surface of the transparent layer and the surface of the reflective layer one or more gas-filled interconnected buffer spaces are realized at positions distributed over the interface between said layers.

Abstract: According to the present invention, the apparatus is provided with a single laser light source and arranged so that light from the laser light source is divided into a plurality of beams by a grating and the plurality of beams are converged to form a plurality of light spots on a recording film by an optical system, whereby in writing information onto a recording film, overwriting to perform erasing and writing at the same time is carried out and an error check on the recorded information is performed in real time while a magnetic field which is polarity-inverted or intensity-modulated in accordance with the recording information is applied to the recording film.

Abstract: An apparatus for operating a magneto-optic medium includes a magnetic biasing field developing device for developing a magnetic biasing field which is applied to the magneto-optic medium when the magneto-optic medium erases or records data. Additionally, a neutral-position controller is provided for positioning permanent magnets of the magnetic biasing field developing device in a neutral position with respect to the medium when the magnetic biasing field developing device is switched off. Thereby, the neutral-position controller maintains the medium at the neutral position with respect to the permanent magnets until the magnetic biasing developing device is switched on and the permanent magnets are placed in a field applying position.

Abstract: An optical disc recording/reproducing apparatus for recording and reproducing data using an optical disc as the recording medium, wherein use is made of an optical disc (1) having pit regions (2a) with servo pits and data regions (2a) on which data will be written, that are alternately provided along the circumferential direction, reference clocks are formed in synchronism with said servo pits, and a laser diode (21) is driven by pulses in synchronism with the reference clocks to write or erase the data, thus enabling the life of the laser diode to be lengthened and the disc capacity to be effectively utilized.

Abstract: The present invention relates to magneto-optical recording medium. The recording medium comprises a magnetic film and a reflective film both provided on a substrate. The reflective film comprises silver (Ag) and manganese (Mn) or silver (Ag), manganese (Mn) and tin (Sn). The magneto-optical recording medium gives excellent CN ratio and recording sensitivity.

Abstract: A bias magnetic field apparatus for opto-magnetic disk apparatus includes a permanent magnet provided so as to closely oppose a side of an opto-magnetic disk opposite the side opposed by the optical head, the permanent magnet rotataably movable around an axis of rotation and having different magnetic poles at each end with respect to the axis of rotation, and one of the magnetic poles opposing the opto-magnetic disk to impress a bias magnetic field to the opto-magnetic disk, a stepping motor to rotate the permanent magnet, detect means for detecting a rotational position of the permanent magnet, where one of the poles of the permanent magnet substantially opposes the disk, and control means for driving the stepping motor so that the permanent magnet is stopped at a rotational position where one of said poles of the permanent magnet opposing the opto-magnetic disk and at the same time so that the permanent magnet is rotated 90.degree.