Abstract: An optical disk has a lead-in region provided at the inner circumference side and a user region provided at the outer circumference side. Pit string 3 of pits of different depths is formed in the lead-in region. Light beam reflected from the pit string is detected by detector and TPP and RF signals are output by differential amplifier and addition amplifier. A ternary signal is restored from pits based on the TPP and RF signals. Information is recorded by pits of the same depth in the user region. Recording information in the depth direction in the lead-in region increases the recording capacity thereof. The information recorded in the depth direction in the lead-in region cannot be transferred to a user region of another optical disk.

Abstract: A thermomagnetic recording and reproducing head includes a floating slider, and a heating head, a reproduction-use magnetic head as an MR head and a recording-use magnetic head as a thin-film inductive head mounted on the floating slider in this order from an upstream side of a track. The heating section of the heating head is formed by boron nitride or ruthenium oxide, and has a width narrower than the widths of the reproduction-use magnetic head and recording-use magnetic head. Moreover, the recording layer of a disk medium is made from an N-type ferrimagnetic material, the coercive force of the recording layer at a recording temperature and saturation magnetization thereof at a reproduction temperature are adjusted, and the compensation temperature of the recording layer is adjusted to be substantially room temperature.

Abstract: On an optical disk, a string of a plurality of pits having two different depths is formed. Quantity of light reflected from the pit string is detected by a photoreceptor element, and based on the detected quantity of reflected light, a pit depth detecting unit detects depth of each pit. Based on the detected quantity of reflected light, a servo signal generating unit generates a tracking servo signal. An output control unit supplies the generated tracking servo signal when a pit of such depth that is to be reproduced is tracked, and holds and supplies an immediately preceding tracking servo signal when a pit of different depth is being tracked, based on the result of detection by the pit depth detecting unit.

Abstract: A magneto-optical memory medium according to the present invention comprises a reproducing layer, which has in-plane magnetization at room temperature and perpendicular magnetization when heated to above a predetermined temperature by a reproducing light beam; a recording layer, which is magnetostatically coupled to the reproducing layer; and an in-plane magnetized layer, provided adjacent to the recording layer, which has a Curie temperature at the above-mentioned predetermined temperature. In this medium, at temperatures below the predetermined temperature, signals recorded at high density in the recording layer are masked, and the above-mentioned magnetostatic coupling is suppressed, by magnetic masking by the in-plane magnetized layer.

Abstract: A magneto-optical recording medium is composed of a base which has a property that a light can be transmitted therethrough, a readout layer formed on the base, which has in-plane magnetization at room temperature, whereas, a transition occurs from in-plane magnetization to perpendicular magnetization as the temperature thereof is raised and a recording layer formed on the readout layer for recording information magneto-optically. A recording and reproducing method and the optical head are designed for the magneto-optical recording medium. By the recording and reproducing method using the optical head, information recorded at high density can be reproduced.

Abstract: A storage medium includes at least a storage layer, a non-magnetic layer, a storage supplementary layer, an anti-oxidation layer, and a ferromagnetism material layer provided in this or reverse order on a substrate. Owing to a magnetic field produced by the storage supplementary layer with an external magnetic field and the concentration of a magnetic flux caused by the ferromagnetism material layer, the magnetic field is strengthened at the position of the storage layer, and the magnetic field sensitivity of the storage medium is improved. In a magneto-optical disc device, an optical head having an objective lens and a magnetic head having a coil are disposed on the same side with respect to the storage medium to store information onto the storage medium.

Abstract: A magneto-optical memory medium according to the present invention comprises a reproducing layer, which has in-plane magnetization at room temperature and perpendicular magnetization when heated to above a predetermined temperature by a reproducing light beam; a recording layer, which is magnetostatically coupled to the reproducing layer; and an in-plane magnetized layer, provided adjacent to the recording layer, which has a Curie temperature at the above-mentioned predetermined temperature. In this medium, at temperatures below the predetermined temperature, signals recorded at high density in the recording layer are masked, and the above-mentioned magnetostatic coupling is suppressed, by magnetic masking by the in-plane magnetized layer.

Abstract: A magnetic recording medium having a recording layer made up of a ferrimagnetic material whose compensation temperature is included within room temperatures and an information recording-reproduction method using the magnetic recording medium. During recording, while a light beam is projected on the recording layer so as to raise the temperature of a recording portion, information is recorded by applying a signal magnetic field from a magnetic head. During reproduction, while a light beam is projected on a reproducing portion of the recording layer so as to raise the temperature thereof, information is reproduced by detecting leakage flux from the reproducing portion by the magnetic head. Thus, during reproduction, no magnetic flux is generated from other portions of the recording layer not irradiated by the light beam. With the arrangement, crosstalk due to leakage flux from adjoining tracks not irradiated by the optical beam can be eliminated.

Abstract: An magneto-optical recording medium includes: a transparent dielectric layer; a reproduction layer that is in an in-plane magnetization state at room temperature and changes into a perpendicular magnetization state with a rise in temperature; a non-magnetic intermediate layer; a recording layer made of a perpendicularly magnetized film; and a protection layer, the layers being formed one after another in this order. The recording layer is made of a rare-earth and transition metal alloy, and the rare earth metal is composed of more than two kinds of rare-earth-metal elements containing Gd. The information stored in a magnetic recording domain is masked with respect to a part that is in an in-plane magnetization state. Consequently, recording can be performed with a less powerful laser beam, and each recording bit can be reproduced independently to produce high quality signals even if the converged light beam covers a neighboring recording bit within its radius.

Abstract: A magneto-optical recording disk includes a recording layer for recording information as a mark and a reproduction layer, laminated with the recording layer, to which magnetization direction of the recording layer is transferred at high temperatures, wherein the reproduction layer and the recording layer are magnetostatically coupled and are not exchange-coupled. The information is read out by using a temperature distribution generated by a light beam for reproduction. The recording layer has, on a side thereof to which the reproduction layer is not provided, a supplementary back layer of a soft magnetic material composed of ferromagnetic material. The magneto-optical disk is designed to generate good CNR and thereby improves recording density even when a short mark is reproduced.

Abstract: A magneto-optical recording medium is arranged so that (1) a first transparent dielectric layer, (2) a reproduction layer showing in-plane magnetization at room temperature while showing perpendicular magnetization in response to temperature rise, (3) a second transparent dielectric layer, (4) a recording layer made of perpendicular magnetization film; and (5) a protective layer are laminated on a substrate in this order. The reproduction layer has a thickness of 5 nm to 30 nm, the second transparent dielectric layer has a thickness of 6 nm to 40 nm, and the recording layer has a thickness of 20 nm to 80 nm. It is possible to separately reproduce individual recording bit even when one or more adjacent recording bits exist within the diameter of the light beam converged onto a target recording bit. This is because the information of a recording magnetic domain of a portion showing in-plane magnetization is masked.

Abstract: A magneto-optical recording medium is composed of a reproducing layer, a recording layer, and an initializing layer, which are laminated in this order. The reproducing layer is provided so that a light beam is projected thereon so as to reproduce information. The recording layer is provided so that information is recorded therein and the information is copied to the reproducing layer at a readout temperature. The initializing layer is provided so that the reproducing layer is initialized at room temperature. Non-magnetic layers are provided between the reproducing layer and the recording layer and between the recording layer and the initializing layer, respectively, so that such two layers are not exchange-coupled each other. The recording layer has a compensation temperature of room temperature, while the initializing layer has a compensation temperature of the readout temperature, which is achieved by temperature rise caused by the projection of the light beam.

Abstract: A magneto-optical recording medium has a recording layer whereon information is magneto-optically recorded. A readout layer is provided on the recording layer. The readout layer has a compensating temperature that is located between room temperature and the Curie temperature. In the readout layer, upon an application of a light beam, the in-plane magnetization occurs at room temperature and a transition from the in-plane magnetization to vertical magnetization occurs as the temperature of the irradiated area of the readout layer rises above a predetermined temperature. By employing this magneto-optical recording medium, with an application of a light beam that is intensity modulated into two levels, only a spot having a temperature not less than a predetermined temperature is involved in the reproduction; therefore, a recorded bit with a size smaller than the diameter of the light beam can be reproduced, thereby greatly increasing the recording density.

Abstract: A magnetic recording medium having a recording layer made up of a ferrimagnetic material whose compensation temperature is included within room temperatures and an information recording-reproduction method using the magnetic recording medium. During recording, while a light beam is projected on the recording layer so as to raise the temperature of a recording portion, information is recorded by applying a signal magnetic field from a magnetic head. During reproduction, while a light beam is projected on a reproducing portion of the recording layer so as to raise the temperature thereof, information is reproduced by detecting leakage flux from the reproducing portion by the magnetic head. Thus, during reproduction, no magnetic flux is generated from other portions of the recording layer not irradiated by the light beam. With the arrangement, crosstalk due to leakage flux from adjoining tracks not irradiated by the optical beam can be eliminated.

Abstract: A magneto-optical recording medium has magnetic multi-layers including a reproductive layer, which is a magnetic layer having perpendicular magnetic anisotropy, for reading out magneto-optically recorded information and a recording layer, which is a magnetic layer having perpendicular magnetic anisotropy, for magneto-optically recording information. In the magneto-optical recording medium, the following conditions are fulfilled:H.sub.C1 (ta)+.sigma.w(ta)/2M.sub.S1 (ta)h.sub.1<-H.sub.C1 (t)+.sigma.w(t)/2M.sub.S1 (t)h.sub.1, and40(nm).ltoreq.h.sub.1 .ltoreq.120(nm)where h.sub.1 is the thickness of the reproductive layer, H.sub.C1 (ta) is coercive force of the reproductive layer at room temperature (ta), M.sub.S1 (ta) is saturation magnetization of the reproductive layer, M.sub.S2 (ta) is saturation magnetization of the recording layer, .sigma.w(ta) is magnetic domain wall energy of the magnetic domain wall formed between said reproductive layer and the recording layer, H.sub.

Abstract: A magneto-optical recording medium comprising a readout layer and a recording layer has a relationship that an external magnetic field H1 is smaller than an external magnetic field H4, where the H1 is a minimum external magnetic field necessary to make a magnetization direction of the readout layer direct to the direction reverse to a magnetization direction of the recording layer substantially at the room temperature, and the H4 is a maximum external magnetic field necessary to make the magnetization direction of the readout layer direct to the direction same as the magnetization direction of the recording layer at an high temperature not lower than a predetermined temperature. Moreover, the magneto-optical disk is provided, between the readout layer and the recording layer, with an intermediate layer which inhibits an effective bias magnetic field from the recording layer to the readout layer at the room temperature.

Abstract: A magneto-optical memory device is provided with a base whereon a first magnetic film which exhibits in-plane magnetization at room temperature and exhibits perpendicular magnetization at above room temperature, a second magnetic film having its Curie temperature above room temperature; and a third magnetic film having its Curie temperature set above the Curie temperature of the second magnetic film, which exhibits perpendicular magnetization in a temperature range between room temperature and Curie temperature are laminated in this order. When recording, the temperature of the third magnetic film is raised to the vicinity of its Curie temperature, and information is recorded thereon by an external magnetic field. As the magnetization of the second magnetic film having a temperature rise above its Curie temperature disappears, an exchange coupling force is not exerted between the first magnetic film and the third magnetic film.

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 medium has a substrate through which a light beam is transmitted and a recording-reproduction layer. The recording-reproduction layer, which exhibits an in-plane magnetization characteristic at the first temperature while still containing magnetization components in the perpendicular direction corresponding to information, comes to exhibit a perpendicular magnetization characteristic above the second temperature higher than the first temperature. In this magneto-optical recording medium, information is reproduced by utilizing a temperature distribution of the recording-reproduction layer being subjected to irradiation of a light beam and by raising the temperature of a portion within a light spot of the light beam from the first temperature to the second temperature.

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.