Abstract: An optical pick-up for selectively reading and writing an optical and magneto-optical recorded medium, in which light projected on the recorded medium is reflected therefrom and directed onto one of two photodetectors, depending on the polarization of the light. The recorded medium has magnetic domains for storing data and a magneto-optical signal is generated from the difference between the two photo voltages from the two photodetectors. The magneto-optical signal represents the data stored in the magnetic domains. The recorded medium also stores data in pit forms, and an optical signal is generated from the sum of the photovoltages of the two photodetectors, to represent the data stored in the pit forms. The arrangement is suitable for reading out simultaneously the optical signal and the magneto-optical signal.

Abstract: An over write capable multi-layer magnetooptical recording medium comprises a substrate on which is stacked a magnetic layer structure including first and second magnetic layers having perpendicular magnetic anisotropy serving as a recording layer and as a reference layer, respectively. The first layer comprises an alloy composition given by the formula:(Tb.sub.U Dy.sub.100-U).sub.V (Fe.sub.100-W Co.sub.W).sub.100-VwhereinU=0 to 60 atomic %V=10 to 30 atomic %W=5 to 40 atomic %and the second layer satisfies the following condition: ##EQU1## wherein .sigma..sub.w : exchange coupling force,M.sub.S2 : saturation magnetization of second layerH.sub.C2 : coercivity of second layer, andt.sub.2 : film thickness of second layers.

Abstract: A method of this invention is a non-overwritable method of recording information on a magnetooptical recording medium in which at least two layers including a first layer comprising a magnetic thin film having a perpendicular magnetic anisotropy, and a second layer comprising a magnetic thin film having a perpendicular magnetic anisotropy, and having a Curie temperature higher than or almost equal to a Curie temperature of the first layer are stacked to be exchange-coupled to each other, and a direction of magnetization of only the second layer can be aligned in a predetermined direction by a first external field at a room temperature while a direction of magnetization of the first layer is left unchanged. The medium which has already been set in a state wherein the direction of magnetization of the second layer is aligned in the predetermined direction, and a interface magnetic wall is formed between the first and second layers is prepared. A beam is radiated on the prepared medium while rotating the medium.

Abstract: A magnetooptic recording medium cartridge which accommodates a double face type disk-like magnetooptic recording medium with which an overwriting can be performed by modulating only the intensity of a laser beam in accordance with two-valued information to be recorded, without modulating a recording magnetic field. The cartridge has two initial auxiliary magnetic field (Hini.) applying devices adapted to produce magnetic fields directed opposite to each other.

Abstract: A magnetooptic storage member is scanned by a single laser beam. The beam intensity is sufficient to heat a localized area of the storage member to be above the Curie temperature for enabling reversing the remanent magnetization of the localized area. Such localized area is subjected to a magnetic bias field for directing which of the remanent directions shall be assumed in the localized area. The storage member and laser beam are relatively moved such that a front or leading portion of the localized area does not reach the Curie temperature. The light reflected from this leading portion, which moves with the laser beam relative to the storage member, is detected for indicating the initial remanent state of the localized area before any changes are made by the combination of the magnetic bias field and the laser beam.

Abstract: A magneto-optical recording/reproducing device which records information by irradiating a light beam of constant intensity on a magneto-optical recording medium while simultaneously applying a magnetic field thereon through a recording magnetic head; and which reproduces the recorded information through a reproducing magnetic head. The magneto-optical recording medium has a magnetic film formed on a translucent substrate and the magnetic field applied through the recording magnetic head reverses in response to the information to be recorded. The recording magnetic head and the reproducing magnetic head are integrally provided on a single magnetic core in order to set their positions easily with respect to each other. By making a magnetic core end-face of the reproducing magnetic head smaller than a light beam spot, information recorded on areas smaller than the light beam spot can be reproduced.

Abstract: A magneto-optical disk unit has a first magnetic-field generator for generating a magnetic field corresponding to a frequency in a recording signal frequency band and a second magnetic-field generator for generating DC magnetic fields of both north-seeking and south-seeking poles in a non-contact manner with a loaded magneto-optical disk. The first magnetic-field generator has a slider part for sliding over a loaded magneto-optical disk in a floating manner using an aerodynamic effect. The unit further has a transfer driver for moving the first and second magnetic-field generators in a direction parallel to the loaded magneto-optical disk and a rotary plate for vertically moving the first magnetic-field generator.

Abstract: A magneto-optical disk drive in which a bias magnetic field coil is mounted on a cassette holder and movable into and out of contact with the cassette holder. A coil base carrying the coil is moved by connecting rods which are rotatably mounted on the cassette holder which is movable while receiving a cartridge therein. The connecting rods are rotated on the basis of a difference between the displacement of a body base which is stationary and the displacement of the cassette holder, whereby the coil base connected to the ends of the connecting rods is moved.

Abstract: A method of and system for utilizing circularly polarized microwave radiation in order to provide for the direct overwriting of previously recorded data on a single-layer magneto-optical disk is disclosed in which a microwave source is used to generate a sinusoidal magnetic wave having a fixed magnitude and fixed frequency which is applied to a phase shift switch whose phase is shifted between right circular and left circular polarization states, depending upon each bit of binary data to be recorded. The output from the phase shift switch is fed to a microwave antenna which is utilized to radiate the right circular or left circular polarized microwave signal to a small area of the magnetic film utilized in a magneto-optical disk which is heated by a focused laser beam at the moment during which recording at that location is desired.

Abstract: In a recording apparatus employing a magneto-optical effect, and in which a light beam irradiates a region of a magneto-optical disc while a magnetic field acts on the disc at such region and is modulated by coded data in accordance with a predetermined modulation system; the light beam is intermittently energized by drive pulses, and the energizing of the light beam is inhibited at times corresponding to transitions in the coded data when the ratio Tmin/Tw is greater than 1, in which Tmin is the minimum length between transitions in the coded data and Tw is a window margin for the modulation system employed for modulating the magnetic field.

Abstract: A magneto-optic recording medium has a cartridge provided with a magnetization direction indicating portion for indicating the direction of magnetization of a second magnetic layer. Alternatively, the direction of magnetization of the second magnetic layer is recorded in advance in the first magnetic layer. The direction of magnetization of the second magnetic layer indicated or recorded is detected and recognized. A magnetic field oriented in an opposite direction to the direction of magnetization detected is imparted to the magneto-optic recording medium. Alternatively, predetermined information is recorded in the first magnetic layer, the direction of magnetization of the second magnetic layer is detected on the basis of a signal reproducing that information, and the direction of a magnetic field to be applied to the magneto-optic recording medium is set on the basis of the direction of magnetization thus detected.

Abstract: A device is for specifying and calculating a reproduction time of an optical disk player such that the reproduction time is specified and calculated to coincide with a recording length of one side of a magnetic tape. The optical disk player reproduces audio information stored on an optical disk in the form of a plurality of recorded audio segments. The magnetic tape is used to record at least one of the plurality of recorded audio segments reproduced by the optical disk player.

Abstract: A disc-shaped recording medium is used in a recording/reproducing apparatus in which a light beam is arranged to scan along a groove formed as a concentrical or spiral recording track, to record or reproduce data. Additional data which has preeviously been recorded on the disc-shaped recording medium in the shape of irregularities, such as address data indicating each recording track, is previously recorded within the groove in the shape of substantially sinusoidal irregularities of an amplitude which is smaller than the depth of the groove. Thus, if new data is recorded over the additional data, it is possible to easily separate the additional data and the newly-recorded data from each other during reproduction, so that the recording density can be improved.

Abstract: The present invention is a method for transmitting a desired digital video or audio signal stored on a first memory of a first party to a second memory of a second party. The method comprises the steps of transferring money via a telecommunications line to the first party from the second party. Additionally, the method comprises the step of then connecting electronically via a telecommunications line the first memory with the second memory such that the desired signal can pass therebetween. Next, there is the step of transmitting the desired digital signal from the first memory with a transmitter in control and in possession of the first party to a receiver having the second memory at a location determined by the second party. The receiver is in possession and in control of the second party. There is also the step of then storing the digital signal in the second memory.

Abstract: This invention relates to a magnetooptical recording medium that is capable of direct overwriting by light intensity modulation without using a separate source for generating an external magnetic field and that has four magnetic layers superposed on a substrate, wherein said magnetic layers has vertical magnetic anisotropy and any two adjacent layers being bound by exchange force. The medium is characterized in that a fifth magnetic layer not bound by exchange force is provided over the fourth magnetic layer or that a layer made of a rare earth element/transition metal alloy in which the magnetization of rare earth elements is dominant is provided between the first and second magnetic layers which are bound together by exchange force.

Abstract: A resonant AC circuit includes a network of switching elements (e.g., power field-effect transistor) by which the direction of current flow through a coil can be selectively switched at each time in the current cycle, when the current amplitude is substantially zero. Such circuit is particularly advantageous and useful in magneto-optic recording systems for switching the polarity of a magnetic field enabling the direct-overwriting of information on a previously recorded magneto-optic recording element at a high data transfer rate.

Abstract: In a magneto-optical signal reproducing apparatus for reading out a signal recorded on a magneto-optical recording medium by an optical pickup device so as to provide a magneto-optical signal which, in turn, is level-discriminated on the basis of a reference level to reproduce data therefrom, the reference level is controlled in accordance with a level of an in-phase signal component provided from the optical pickup device, thereby enabling stable data reproduction.

Abstract: A magneto-optical information storage medium includes a substrate, a recording layer formed on the substrate and having an axis of easy magnetization extending in the direction perpendicular to its surface, a nonmagnetic layer formed on the recording layer, and a bias layer, formed on the nonmagnetic layer, for generating bias magnetic field H.sub.B (T) in accordance with a temperature. The magnetization of the recording layer is reversed by bias magnetic field H.sub.B (T) in first and second magnetization reversal temperature regions T.sub.W and T.sub.E (T.sub.W >T.sub.E). Information is recorded on such a magneto-optical information storage medium by radiating a first laser beam having a first power level for heating an irradiated portion to a temperature in region T.sub.W. In addition, information erasing is performed by radiating a second laser beam having a second power level which is lower than the first power level and heats an irradiated portion to a temperature in region T.sub.E.

Abstract: Methods for directly over-writing the binary data value of a bit of digital data, stored in a particular one of a multiplicity of microscopic storage regions of a thin-film magneto-optic recording layer, in the absence of a substantial externally applied bias magnetic field, employ a magnetic material having a compensation temperature a few tens of degrees centigrade above room temperature. A source of energy is energized to heat the particular storage region to a sufficiently high temperature that the self-demagnetization field of the recording layer material inverts the net magnetic moment of that region. Multiple over-writing of the long-term stable stored data values can be provided.

Abstract: In a magneto-optical recording apparatus, in which light spots are sequentially formed on a magneto-optical disk at the timing of a predetermined reference clock signal while a modulating magnetic field, which is reversed in polarity as a function of record data in synchronism with the reference clock signals, is applied to the disk for magnetically recording the record data thereon; the timing of polarity reversal of the modulating magnetic field with respect to the reference clock signal is delayed as a function of the magnetic and/or temperature characteristics of the magneto-optical disk to permit a magnetized domain to be formed at the correct position with respect to the timing of the reference clock signal.