Abstract: An erasable electro-optic storage disk for use in focused laser beam operated data handling systems comprises a semiconductor substrate with a storage layer arranged on top of it that is capable of trapping charge carriers. Electric contacts are connected to the semiconductor substrate and to the storage layer, respectively. An energy barrier with associated depletion zone is formed in the substrate near the interface with the storage layer. Upon simultaneous application of a control voltage to the contacts and of a focused laser beam directed at a storage site, electron pairs are generated in the depletion zone, and charge carriers are transferred towards the interface. This causes a reduction of the depletion zone and thus of the voltage over the depletion zone, and an increase of the field in the storage layer, whereby charge carriers are injected into and trapped in the storage layer; method of recording, reading data and apparatus therefor.

Abstract: A record-carrier body is described, in which a user can record information by means of optical radiation, which record-carrier body has a relief structure of optically detectable servo-track portions and sector addresses. If the maximum width of the servo-track portions and the areas in the sector addresses is at least of the order of half the track period, the servo track portions can be tracked in an optimum manner and the sector-address areas and the information areas recorded by the user provide a read signal of high amplitude.

Abstract: An opto-magnetic disk unit is constructed so that predetermined areas existing in the front of the unit recording areas can be detected. In addition, at least one of first and second saturation magnetizations are recorded on each of the detected predetermined areas. At the time of reproduction, signal processing on the output of the pickup is performed after a part of the output of the pickup corresponding to the one section of the predetermined area is clamped to a predetermined level. Also at the time of reproduction, gain controlling of a circuit for signal processing the output of the pickup may be performed based on the level difference between the signal read from a first saturation magnetization section and the signal read from a second saturation magnetization section. An opto-magnetic disk is also provided having recording areas including at least one of first and second magnetization saturation levels arranged in the front of the unit recording areas.

Abstract: A reproducing apparatus mixes the voice information from a microphone and the information reproduced from a recording medium in which a vocal signal plus an instrumental signal is contained as a first signal in a first channel and only an instrumental signal is contained as a second signal in a second channel. A first mixing circuit mixes the first signal and the second signal. The output of the first mixing circuit is mixed by a second mixing circuit with the voice information from the microphone. A control circuit or audio detecting circuit provides a control signal in accordance with the level of the voice information from the microphone. The control signal controls a selection control circuit to gradually and smoothly vary the mixing ratio of the first signal and the second signal when mixing these two signals.

Abstract: An optically-recorded medium in which a reflecting optomagnetic layer is applied to a transparent substrate layer. The recorded medium stores data magnetically and by pits. The magnetically stored data and the pit stored data are superimposed on each other, so that every spot and region on the recorded medium stores both magnetically stored data and pit stored data. The recorded medium is not divided into separate regions for magnetically stored data and pit stored data, and the magnetically stored data and pit stored data may be read out simultaneously by a single light beam.

Abstract: An optical recording disc comprising a resin layer of resin material formed on a relatively rough surface of each transparent disc substrates, the resin material having approximately the same refractive index of light as the refractive index of the transparent disc substrate, and a recording layer formed on each of said resin layers. Accordingly, the optical recording disc enables a decrease in production costs and to write and read an information signal into and from the recording layer at an improved signal to noise ratio as compared to a conventional optical recording disc.

Abstract: A magneto-optic recording a reproducing apparatus including a magneto-optic information-carrying medium having three magnetic layers. A magnetic bias field is generatedd by a third layer which is premagnetized in the direction parallel to the thickness thereof. A second layer is magnetized by a magnetizing unit. The laser beam incident on the layers is controlled to three intensities for writing and reading information.

Abstract: An optical disc record carrier having a radiation-sensitive surface and a spiral or concentric pattern of information tracks thereon. The radial displacement of each track is modulated to produce a periodic radial wobble, the frequency of such periodic displacement being modulated by a position-information signal identifying the relative positions of the tracks. During recording or reading of information on the tracks the track modulation is read by a scanning beam. A clock signal for controlling scanning velocity is recovered from the track displacement modulation, and an FM demodulator recovers the position-information signal from the frequency modulation of such displacement.

Abstract: For magneto-optic data recording, permanent magnets are used to produce a magnetic field with a variable field strength. The field strength is varied by controlled rotation of the magnets about their longitudinal axis, which also allows inversion of the direction of the magnetic field. The magnets are oriented such that their combined fields produce a resultant force continuously substantially perpendicular to the recording medium despite rotation of the magnets.

Abstract: An apparatus for providing a bias magnetic field coincident with the read/write laser in a magneto-optic recording system is disclosed, with special utility for systems wherein the thickness or configuration of the media necessitates a functioning bias magnet being located on the same side of the media as the read/write laser.

Abstract: Apparatus for selectively reversing a magnetic bias field (e.g., to switch between recording and erasing modes in a magnetooptic recording system) includes a rod-shaped permanent magnet having its magnetic poles oriented along the cross-sectional dimension thereof. The rod is mounted for axial rotation within a concentrically arranged tube of electrically conductive material, and means are provided for biasing the rotational position of the magnet toward either of two nominal positions, 1/2.degree. apart. Upon being subjected to a torque, the magnet rotates toward either of its nominal positions, and oscillatory movement about such nominal positions is damped by eddy-current-produced magnetic forces in the conductive tube.

Abstract: A magneto-optical memory apparatus has an optical head for applying a light to a substrate of a recording medium such as a magneto-optical disk having a magneto-optical recording film formed on the substrate and continuously applying a high power laser beam in a record mode, and a floating magnetic head arranged on the opposite side of the recording medium to the side of the optical head and adapted to be kept at a substantially constant distance from the recording medium by an air pressure created between the magnetic head and the recording medium by the movement of the recording medium, for applying, in the record mode, a magnetic field which is polarity-inverted or intensity-modulated according to information to be recorded, to the magneto-optical recording film.

Abstract: Modulating the intensity of directed energy for thermal writing of memory cells overwrites bits of either state in a storage layer of magnetic material irrespective of the preexisting condition of the cell without employing a magnetic field whose origin is external to the storage layer. Directed energy is synchronized with the medium by superimposing, preferably nonmagnetically, self-timing information on the medium itself and synchronously recovering the self-timing information to assist in directing energy to the medium. The medium itself has a magnetic layer plus recoverable timing information fixed in the medium along a predetermined path preferably embodied in a fixed periodic uniform variation in the nonmagnetic reflection properties along the track.

Abstract: A method of reproducing a signal from a magneto-optical recording medium is disclosed in which the medium is formed of a first magnetic film, a second magnetic film and a third magnetic film which are magnetically coupled to one another at room temperature T.sub.RT, wherein the Curie points Tc1, Tc2 and Tc3 of the first, second and third magnetic films are in the relationship of Tc2>T.sub.RT Tc2<Tc1, and Tc2<Tc3, and the coercive force Hc1 of the first magnetic film is small in the vicinity of the Curie point Tc2 of the second magnetic film, and the coercive form Hc3 of the third magnetic film is larger than a minimum required magnetic field intensity within a temperature range between the room temperature TRT and a predetermined temperature T.sub.PB which is higher than the Curie point Tc2 of the second magnetic film. A signal is reproduced from the magneto-optical recording medium by heating it to the predetermined temperature T.sub.

Abstract: An optical memory storage media is described, e.g. a compact disc. A method of preparing the media (e.g. discs) is also taught. The storage media is formed from a substrate material having tightly bonded to the surface a highly reflective soft metal alloy formed of, for example, an alloy including at least five percent by weight of each of at least two metals selected from the group consisting of cadmium, indium, tin, antimony, lead, bismuth, magnesium, copper, aluminum, zinc and silver.

Abstract: A magneto-optic information-carrying medium comprises three magnetic layers. A magnetic bias field is generated by a third layer which is premagnetized in the direction parallel to the thickness thereof.

Abstract: A magnetooptical recording method for recording data using a bit having upward-magnetization and a bit having downward-magnetization on a recording layer of a magnetooptical-recording medium comprises the steps of using, as the medium, a multilayered magnetic recording medium consisting of a first layer having a perpendicular magnetic anisotropy acting as a recording layer, and a second layer having a perpendicular magnetic anisotropy acting as a reference layer; moving the medium; applying an initial field so that, before recording, the direction of magnetization of the recording layer is left unchanged and that of the reference layer is aligned either upward or downward; radiating two adjacent laser beams, i.e.

Abstract: An optical pick-up for selective playback and recording on a magneto-optically recording medium, in which light is projected from a source onto the medium. The light is provided with a direction of a polarization, and is either reflected from the recording medium or is transmitted through the medium. The reflected or transmitted light becomes deflected onto a predetermined one of several photodetectors, depending on the direction of polarization of the light. The intensity of the reflected light or the transmitted light is held constant to minimize noise components that result from the optical properties of different recorded media as well as from the light. By holding the light intensity constant, moreover, precise readjustment to each of the different recording media that may be used, is not necessary.

Abstract: A method and apparatus are revealed for recording information on a record carrier (1) having a magneto-optical recording layer (2), a pattern of magnetic domains (23, 24) having a first and a second direction of magnetization being formed in the recording layer (2). In accordance with the method, areas (22) of the recording layer are heated by the radiation pulses (20). The heated areas (22) are magnetized by means of a coil (12) which is energized with energizing-current pulses (21) which lag the radiation pulses (20) to such an extent that cooling of the areas (22) takes place substantially during the generation of the energizing pulses (12).

Abstract: An optical information recording/reproducing apparatus includes signal recording means for recording a signal on a film. The signal is recorded by raising the temperature of the film with a writing laser beam. A signal reproduction apparatus reproduces the signal by irradiating the film with a reading laser beam. There is an optical system provided in common to both the writing laser beam and the reading laser beam. The signal recorded on the film is reproduced substantially simultaneously with the recording of the signal in order to allow for confirmation of the signal that has been recorded. A modulating circuit is provided for modulating the intensity of the writing laser beam with a frequency of at least twice as high as the maximum frequency of the signal to be recorded.