Abstract: An optical disk apparatus includes a light source, an objective lens, a slider to hold the lens, a suspension to support the slider, a mirror located below the slider, and a seek mechanism to move the mirror and the slider in the tracking direction of an optical disk to be used. The mirror upwardly reflects light traveling in a predetermined horizontal direction, thereby causing the reflected light to enter the objective lens arranged above the mirror. The mirror is rotatable about a prescribed axis for causing the reflected light to shift in the above-mentioned horizontal direction.

Abstract: An optical head unit used for an optical disk apparatus is provided. The optical head unit includes an object glass assembly for focusing a laser beam from a light source on an optical disk, an actuator movable at least in a focus control direction, a carriage for supporting the actuator and moving the actuator in a track control direction, and a slider which is attached to the carriage and capable of adjusting its posture in relation to a surface of the optical disk. The object glass assembly is provided with a plurality of lens units. Each lens unit includes at least one lens. One of the plural lens units is supported by the slider.

Abstract: A magneto-optical recording medium which is adapted to realize a partial ROM with remarkable facility in providing software. The magneto-optical recording medium comprises a transparent substrate, a volatile magnetic recording layer formed on the transparent substrate and having a Curie temperature approximately equal to or lower than a temperature raisable in a recording/reproducing apparatus of a user, and a nonvolatile magnetic recording layer formed on the volatile magnetic recording layer and having a Curie temperature higher than the temperature raisable in the recording/reproducing apparatus of the user; wherein the nonvolatile magnetic recording layer is not initialized and is retained in a state immediately after manufacture of the medium.

Abstract: A magneto-optical medium and a reproducing device for the medium has, in the magneto-optical medium, a mark in a magneto-optical recording area is so formed as to correspond to one of "1" and "0" of data to be recorded, and in a pre-formatted recording area, a pit in formed so that an edge of said pit corresponds to one of "1" and "0" of the data to be recorded. Therefore, when the magneto-optical recording area and the pre-formatted recording area have substantially the same linear recording density, only one pit exists in the spot area of a reproducing beam. As a result, excellent characteristics can be obtained due to a super resolution effect.

Abstract: A magneto-optical recording medium adapted for reproduction of a high resolution signal without the necessity of a reproducing magnetic field. The magneto-optical recording medium comprises a transparent substrate and deposits of a reproducing layer, a switch layer and a recording layer formed on the transparent substrate successively. The reproducing layer is a perpendicular magnetization film at a room temperature but is turned to an in-plane magnetization film when heated beyond a predetermined temperature. Each of the switch layer and the recording layer is a perpendicular magnetization film. The respective Curie temperatures Tc1, Tc2 and Tc3 of the reproducing layer, the switch layer and the recording layer satisfy the relationship of Tc1>Tc3>Tc2.

Abstract: A head driving apparatus has two yokes each having two generally parallel members which extend respectively in the direction generally perpendicular to the optical axis of a lens, and the yokes are disposed on both sides of the two side surfaces of the head. Two tubular head driving coils are fixed to the head and externally fitted on the member of each yoke, which is nearer to the head. At least a first magnet is fixed to the member of each yoke lying further from the head. A plurality of second magnets are fixed to the head and oppose the first magnets. The head is supported in a non-contact state by the repulsive forces of the first magnets and the second magnets, and the head is driven by energizing the head driving coils. An optical disk apparatus is equipped with the head driving apparatus.

Abstract: A system reproduces data from an optical disk in which a signal obtained by encoding recording data in accordance with a recording rule including a rule corresponding to a partial response class I characteristic has been recorded. The system includes an optical head for reproducing a signal from the optical disk, an analog-to-digital converter for sampling the signal reproduced by the optical head at predetermined timing and for outputting sampling data, a determination unit for determining, based on the sampling data from the analog-to-digital converter, a transition state of data to be reproduced in accordance with a transmission line characteristic of the reproduction system for the optical disk, and a data decision unit for deciding maximum likelihood reproduction data at present timing based on the determination result obtained by the determination unit.

Abstract: The present invention provides a magneto-optical medium and a reproducing device for the medium. In the magneto-optical medium, a mark in a magneto-optical recording area is so formed as to correspond to one of "1" and "0" of data to be recorded, and in a pre-formatted recording area, a pit in formed so that an edge of said pit corresponds to one of "1" and "0" of the data to be recorded. Therefore, when the magneto-optical recording area and the pre-formatted recording area have substantially the same linear recording density, only one pit exists in the spot area of a reproducing beam. As a result, an excellent characteristics can be obtained due to a superresolution effect.

Abstract: A magneto-optical recording medium improved in reproduction stability and carrier-to-noise ratio by enlarging the magnetic anisotropy of a magnetic film. The magneto-optical recording medium is composed of a transparent substrate, a first dielectric film laminated on the transparent substrate, a magnetic film laminated on the first dielectric film, and a second dielectric film laminated on the magnetic film. The second dielectric film is formed from a material different from a material of the first dielectric film, and has film stress different from film stress of the first dielectric film. Accordingly, the coercive force and the magnetic anisotropy of the magnetic film can be enlarged.

Abstract: A magneto-optical recording medium which is adapted to realize a partial ROM with remarkable facility in providing software. The magneto-optical recording medium comprises a transparent substrate, a volatile magnetic recording layer formed on the transparent substrate and having a Curie temperature approximately equal to or lower than a temperature raisable in a recording/reproducing apparatus of a user, and a nonvolatile magnetic recording layer formed on the volatile magnetic recording layer and having a Curie temperature higher than the temperature raisable in the recording/reproducing apparatus of the user; wherein the nonvolatile magnetic recording layer is not initialized and is retained in a state immediately after manufacture of the medium.

Abstract: The invention provides magneto-optical recording method and apparatus, in which a space area on a magneto-optical recording medium is irradiated with a beam in the form of a pulse train in which a bottom power and an assist power are alternately repeated, so as to rapidly change the temperature at the front edge of a recording mark, thereby preventing jitter from increasing.

Abstract: A magneto-optic disk recording system capable of canceling shifts of the front edge and the rear edge of the record mark due to accumulation of heat. The recording system includes a magneto-optic disk having a record magnetic film, and a magnet for applying a bias magnetic field to the disk in the direction perpendicular thereto. The recording system further includes a laser diode for generating laser beams, an optical head for focusing the laser beam on the disk, a pulse generator for generating square wave pulses with a predetermined period, and a duty ratio controller for alternately increasing and decreasing the duty ratio of the square wave pulses every time data "1" of binary record data is generated. The laser diode is driven by a constant-current circuit for write power. There is connected a switch between the laser diode and the constant-current circuit for write power.

Abstract: A system reproduces data from an optical disk in which a signal obtained by encoding recording data in accordance with a recording rule including a rule corresponding to a partial response class I characteristic has been recorded. The system includes an optical head for reproducing a signal from the optical disk, an analog-to-digital converter for sampling the signal reproduced by the optical head at predetermined timing and for outputting sampling data, a determination unit for determining, based on the sampling data from the analog-to-digital converter, a transition state of data to be reproduced in accordance with a transmission line characteristic of the reproduction system for the optical disk, and a data decision unit for deciding maximum likelihood reproduction data at present timing based on the determination result obtained by the determination unit.

Abstract: An optical recording medium in which a medium identification code is recorded as a nonvolatile mark which is formed through irreversible change of a recording film, such as magnetization characteristic change, deformation and formation of a hole, so as to prevent illegal copying of the optical recording medium, and a recording/reproducing method for the same.

Abstract: A data reproduction apparatus for reproducing data corresponding to front and rear edges of marks is recorded in an optical disk. The apparatus includes an optical head for obtaining a reproduction waveform from the optical disk, an A/D converter for obtaining a real sampling value from the reproduction waveform so as to detect an ascending edge (or a descending edge), an interpolator for obtaining a descending edge (or ascending edge) calculate sampling value through interpolation using the real sampling value, and a maximum likelihood detector for detecting a maximum likelihood signal on the basis of a real sampling value and the interpolated sampling value.

Abstract: The sector formats of adjacent record tracks are made different from each other so that a region of an ID signal of a header part of one of the record tracks is adjacent to a region (VFO part) other than an ID signal of a header part of the other record track and the regions of ID signals are not adjacent to each other. A crosstalk component from the VFO part which is the closest pattern is so small that it little affects the reproduction of an ID signal. Therefore, an ID signal is correctly reproduced.

Abstract: Disclosed is a magneto-optical recording medium adapted for reproduction of a high resolution signal without the necessity of a reproducing magnetic field, whereby the magneto-optical recording medium comprises a transparent substrate, a reproducing layer, a switch layer and a recording layer formed on the transparent substrate successively. The reproducing layer is a perpendicular magnetization film at a room temperature but is turned to an in-plane magnetization film when heated beyond a predetermined temperature. Each of the switch layer and the recording layer is a perpendicular magnetization film. The respective Curie temperatures Tc1, Tc2 and Tc3 of the reproducing layer, the switch layer and the recording layer satisfy the relationship of Tc1>Tc3>Tc2.

Abstract: A system reproduces data from an optical disk in which a signal obtained by encoding recording data in accordance with a recording rule including a rule corresponding to a partial response class I characteristic has been recorded. The system includes an optical head for reproducing a signal from the optical disk, an analog-to-digital converter for sampling the signal reproduced by the optical head at predetermined timing and for outputting sampling data, a determination unit for determining, based on the sampling data from the analog-to-digital converter, a transition state of data to be reproduced in accordance with a transmission line characteristic of the reproduction system for the optical disk, and a data decision unit for deciding maximum likelihood reproduction data at present timing based on the determination result obtained by the determination unit.

Abstract: A system for reproducing data recorded in an optical disk as a signal obtained by modulating the data in accordance with a predetermined partial response characteristic, includes an optical head for reproducing the signal from the optical disk, a VCO for generating a clock, an A/D converter for obtaining a sampling value from the reproduction signal in synchronism with the clock, a maximum likelihood decoder for detecting a maximum likelihood decode data on the basis of the sampling value in synchronism with the clock, a demodulator for demodulating the decode data from the maximum likelihood decoder, wherein the maximum likelihood decoder includes a phase error detecting unit for detecting a phase error between the clock and a point of time when the reproduction signal is sampled, and a phase error correcting unit for correcting the detected phase error.

Abstract: A magneto-optic recording medium with a transparent substrate, a first dielectric layer above the transparent substrate, a magnetic layer above the first dielectric layer, a second dielectric layer above the magnetic layer, and a reflecting layer above the second dielectric layer. The magnetic layer is made of a composition modulated material.