Abstract: A magneto-optical recording medium is provided, which makes it possible to reliably reproduce a long mark by increasing a leak magnetic field from a central portion of a continuous recording mark. The magneto-optical recording medium comprises a magnetic layer which is composed of a soft magnetic material and exhibits in-plane magnetization during reproduction of information, the magnetic layer being disposed in contact with a recording layer between the recording layer and a substrate. The flow of the magnetic flux of the magnetic domain formed in the recording layer is controlled by the magnetic layer, and the magnetic flux from the magnetic domain disposed in the recording layer is in a closed state through the inside of the magnetic layer. Accordingly, a leak magnetic field having a sufficient magnetic field intensity is generated from the central portion of the continuous recording mark.

Abstract: Virtual tracks are set so that the rotation center of a magnetic recording medium or the vicinity of the rotation center coincides with the track center of the data information, and positioning servo control is performed. Thus, since it is not necessary to faithfully follow the track center line specified by the servo information that is previously recorded on the magnetic recording medium or magnetooptical recording medium, a vibration is not easily caused in synchronism with the rotation. Therefore, when the rotation center and the pattern center are deviated from each other, since a vibration is not caused in synchronism with the rotation, the magnetic head of the magnetic recorder or the magnetooptical head of the magnetooptical recorder is able to follow tracks with higher precision. Accordingly, the recording density can be increased.

Abstract: An optical recording/reproducing method employs a recording laser beam having a first output and a first wavelength, and a reproducing laser beam having a second output lower than the first output and a second wavelength shorter than the first wavelength. A disk-like recording medium is irradiated with the recording and reproducing laser beams by use of an objective lens having an NA of about 0.55 so that a small mark equal to or smaller than about one fourth of a spot size optically defined from the wavelength of the recording laser beam and the NA of the objective lens is formed on the recording medium by a recording characteristic of the recording medium and a shielding plate provided in an optical system for irradiation with the laser beam. Two-dimensional recording is performed as a recording system to arrange marks at lattice points of a two-dimensional lattice which extend in a track direction and a track radius direction.

Abstract: An optical recording/reproducing method employs a recording laser beam having a first output and a first wavelength, and a reproducing laser beam having a second output lower than the first output and a second wavelength shorter than the first wavelength. A disk-like recording medium is irradiated with the recording and reproducing laser beams by use of an objective lens having an NA of about 0.55 so that a small mark equal to or smaller than about one fourth of a spot size optically defined from the wavelength of the recording laser beam and the NA of the objective lens is formed on the recording medium by a recording characteristic of the recording medium and a shielding plate provided in an optical system for irradiation with the laser beam. Two-dimensional recording is performed as a recording system to arrange marks at lattice points of a two-dimensional lattice which extend in a track direction and a track radius direction.

Abstract: Learning marks are recorded in a learning region preceding a data recording region of the track. The positions of information recording lattice points are staggered by one lattice point between two contiguous tracks. At reading of recorded information, a two-dimensional information leakage amount is detected by the reproduced signals from a learning mark preceding a target information recording lattice point on a track, and from the information recording lattice points immediately before and after the learning mark in question. The equalization coefficients are calculated from leakage amount thus obtained. The crosstalk present in a reproduced signal for the target lattice point is removed by using this equalization coefficients and a pair of reproduced signals from intermediate lattice points which are located immediately before and after the current lattice point and which are not used to record information marks.

Abstract: A magnetic digital storage method and system which can improve a recording density and can reduce a cross-talk upon reproducing. An inputted high-speed digital signal is converted to a plurality of low-speed digital signal sequences by a recording circuit and each of the low-speed signal sequence is recorded onto a plurality of adjacent recorded tracks of a recording medium by integrated parallel recording heads. One servo signal is commonly recorded to the plurality of recorded tracks. Further, when recording the digital signal to the adjacent recorded tracks of the recording medium, a delay of a signal that is applied to each recording head is adjusted such that the phases of magnetic transition points given by the recording signal in the adjacent recorded tracks are not identical in the circumferential direction.

Abstract: An optical information reproducing method, for optically reproducing information recorded on a recording medium, irradiates the recording medium with a laser beam and detects the light returning from the recording medium. When the diffracted light returning from the recording medium is detected, the optical intensity distribution of the diffracted light is detected by a plurality of detectors to produce a plurality of signals, and the signals are calculated to produce a reproduced signal for detecting the information.

Abstract: An optical information recording/reproducing method includes that information is recorded on a rotary disk in an optically discriminative form, a light emitted from a light source is focused on the surface of the disk to form a light spot, the information is scanned with the light spot relative thereto in a rotating direction of the disk, and a reflection light or transmitting light from the disk is collected by an optical system to record or reproduce the information.