Abstract: To provide a regenerative signal evaluation method in which the transition of polarity of a regenerative signal, or the change of polarity in a record mark sequence, is dealt with employing an index in correlation with an error ratio of binarization result by a maximum likelihood decoding. The method comprises detecting a recording series on a state transition path having a certain Euclid distance by the maximum likelihood decoding corresponding to a change of polarity of record code in the recording series, acquiring a likelihood difference between the most probable state transition path and the secondly probable state transition path from branch of state transition paths to merge of state transition paths in the detected recording series, and conducting a statistical processing for the likelihood difference individually corresponding to the change of polarity in the recording series to evaluate the quality of reproducing signal.

Abstract: An optical disk is made of tracks that are magnetically separated from one another by scanning a focused light beam over lands between tracks at a predetermined power and annealing to lower the magnetic anisotropy of a magnetic layer on the lands, and is provided with a power testing region comprising one or more tracks for finding the predetermined annealing power at the location of at least one of the group consisting of a specific region within the data region, a region more to the inner side than the innermost track of the data region, and a region more to the outer side than the outermost track of the data region. Thus, an optical disk and a manufacturing method for the same can be provided that have a high recording density and with which annealing can be implemented in a short time and at the correct annealing width.

Abstract: The object of the present invention is to realize reduction of the level jitter generated from a noise component at a signal saturation level or a waveform distortion in a portion except for signal polarity portions (rising edge and falling edge), and good error characteristics. In the present invention, a predetermined upper or lower limit value is set to reproduction signals, the reproduction signals are subjected to a limiter processing for correcting reproduction signals of the upper limit value or more, or the lower limit value or less to the level of the upper limit value or the lower limit value, respectively, the signal subjected to the limiter processing is subjected to a partial response equalizing (PR equalizing) processing, and PR reproduction is performed to improve the level jitter at PR detection time and the error rate at information reproduction time.

Abstract: An optical disk is made of tracks that are magnetically separated from one another by scanning a focused light beam over lands between tracks at a predetermined power and annealing to lower the magnetic anisotropy of a magnetic layer on the lands, and is provided with a power testing region comprising one or more tracks for finding the predetermined annealing power at the location of at least one of the group consisting of a specific region within the data region, a region more to the inner side than the innermost track of the data region, and a region more to the outer side than the outermost track of the data region. Thus, an optical disk and a manufacturing method for the same can be provided that have a high recording density and with which annealing can be implemented in a short time and at the correct annealing width.

Abstract: A manufacturing method of a domain wall displacement type magneto-optical recording medium comprises the steps of depositing a magnetic layer on a substrate to prepare a disc, and irradiating the magnetic layer with a converged light beam while applying a magnetic field and annealing the magnetic layer a converged light beam between information tracks.

Abstract: By irradiating a light beam between recording tracks of the magneto-optical recording medium, the magnetic anisotropy of at least one layer selected from the group consisting of the domain wall displacement layer and the recording layer formed between the recording tracks can be made lower than that of said layers on the recording tracks, and a bias magnetic field is applied at least between recording tracks while a light beam is radiated. Because of this, initialization of a medium may be conducted simultaneously.

Abstract: A manufacturing method of a domain wall displacement type magneto-optical recording medium comprises the steps of depositing a magnetic layer on a substrate to prepare a disc, and irradiating the magnetic layer with a converged light beam while applying a magnetic field and annealing the magnetic layer a converged light beam between information tracks.

Abstract: Disclosed herein is a testing process for recording for presetting optimum recording power for a domain wall displacement type magneto-optical medium, the process comprising the steps of: recording a first record pattern on an Nth track on the magneto-optical medium; separately recording a second record pattern on an (N−1)th track and an (N+1)th track adjacent to both sides of the Nth track with varied recording power; reproducing the Nth track to detect a change in the pulse width of a reproduction signal; detecting recording power, at which cross writing occurs, on the basis of the detected result; and presetting optimum recording power on the basis of the recording power at which cross writing occurs.

Abstract: The present invention provides a magneto-optical recording method capable of securing a sufficient phase margin, even if a recording power or medium temperature fluctuates, and obtaining a reproduction signal having a preferable quality, wherein the time phases of a laser pulse and a modulation magnetic field are set to a time phase of maximizing in which a recording power margin.

Abstract: According to the present invention, a light beam is radiated to an area between recording tracks while the intensity of a magnetic field from the outside to a magneto-optical recording medium is suppressed to 50 Oe or less, whereby magnetic anisotropy formed between the recording tracks is set to be lower than that of the magnetic layer on the recording tracks, and micro-domains, for example, having a diameter smaller than a half-width of a light beam for reproduction in a film surface direction are formed on recording tracks. Because of this method, the influence of a leakage magnetic field in the magneto-optical recording medium adopting a DWDD reproducing system is alleviated.

Abstract: By irradiating a light beam between recording tracks of the magneto-optical recording medium, the magnetic anisotropy of at least one layer selected from the group consisting of the domain wall displacement layer and the recording layer formed between the recording tracks can be made lower than that of said layers on the recording tracks, and a bias magnetic field is applied at least between recording tracks while a light beam is radiated. Because of this, initialization of a medium may be conducted simultaneously.

Abstract: An optical disk is made of tracks that are magnetically separated from one another by scanning a focused light beam over lands between tracks at a predetermined power and annealing to lower the magnetic anisotropy of a magnetic layer on the lands, and is provided with a power testing region comprising one or more tracks for finding the predetermined annealing power at the location of at least one of the group consisting of a specific region within the data region, a region more to the inner side than the innermost track of the data region, and a region more to the outer side than the outermost track of the data region. Thus, an optical disk and a manufacturing method for the same can be provided that have a high recording density and with which annealing can be implemented in a short time and at the correct annealing width.

Abstract: A manufacturing method of a domain wall displacement type magneto-optical recording medium comprises the steps of depositing a magnetic layer on a substrate to prepare a disc, and irradiating the magnetic layer with a converged light beam while applying a magnetic field and annealing the magnetic layer a converged light beam between information tracks.

Abstract: The present invention provides a domain wall displacement-type magnetooptical recording medium effective for decreasing jitter, in which a conventional herringbone recording mark can be changed to a linear mark. The magnetooptical recording medium of the present invention includes a substrate having lands and grooves, and a magnetic layer deposited on the substrate so as to be magnetically interrupted between the lands and the grooves, wherein the magnetic film deposited on each of the lands has a section having a flat bottom, and a substantially flat top in the central portion of each of the lands, either side having a thickness decreasing in the direction to the side end.

Abstract: A magneto-optical recording-reproducing process for reproducing a record mark by projecting a light beam onto a magneto-optical medium having a memory layer and a readout layer to form a heated region to transfer and enlarge in the heated region a magnetic domain in the memory layer into the readout layer comprises the steps of recording a record mark sequence in the memory layer with correction of the length of the record mark to be shorter than that of a normal interval of code reversal and with correction of the length of the no-record mark to be longer correspondingly thereto, where the magnetic domain in the direction of enlarging the magnetic domain in the readout layer is employed as the record mark, and further comprising reproducing the record mark sequence.

Abstract: Disclosed herein is an information recording-reproducing method, wherein a domain wall is displaced on a recording medium in which information has been recorded, thereby conducting the reproduction of the information, the method comprising, projecting a light spot on the recording medium, relatively moving the light spot and the recording medium, applying a magnetic field modulated according to the information to the site projected by the light spot to form record marks the maximum mark length of which is at most 0.15 times the spot size of the light spot and displacing the domain wall from the front to the back of the moving direction of the light spot by a temperature distribution formed on the recording medium by the light spot, and at the same time detecting the displacement of the domain wall from reflected light of the light spot, thereby detecting the record marks.

Abstract: A method of determining a strength of a reproducing magnetic field for an apparatus for reproducing information from a magneto-optical recording medium by applying an optical beam to the magneto-optical recording medium while the reproducing magnetic field is applied, the magneto-optical recording medium including a record storage layer and a domain wall displacement layer both made of a magnetic film, and the method including the steps of: recording a test signal having a predetermined pattern on the medium; applying the reproducing magnetic field to the medium by changing the strength thereof and at the same time scanning the medium with the optical beam to reproduce the recorded test signal; and detecting an amplitude of the reproduced test signal and setting as the strength of the reproducing magnetic field a value of a predetermined margin added to the strength of the reproducing magnetic field applied when the amplitude satisfying a predetermined condition is detected.

Abstract: Disclosed herein is a magneto-optical recording-reproducing method, wherein a domain wall of a record mark is displaced on a recording medium, thereby conducting the reproduction of information, the method comprising the steps of reproducing the prescribed record signals recorded in the recording medium by plural stages of reproduction power to detect reproduction signals; differentiating the reproduction signals to detect differential signals; and determining the reproduction power on the basis of the amplitude values of the differential signals.

Abstract: A method for recording information on a domain wall displacement type magneto-optical medium comprises forming a magnetic domain such that the magnetic domain is asymmetrical with regard to a center line of a land portion or a groove portion in a tangential direction of the magneto-optical medium perpendicular to a radial direction of the magneto-optical medium. A method for reproducing information recorded by the method for recording information comprises projecting a light spot a center of which light spot, is positioned in one side of the land portion or the groove portion divided by the center line of the land portion or the groove portion from the other side, in which other side a curvature center of a domain wall of the magnetic domain exists, moving the light spot along the land portion or the groove portion, and reproducing information from the magnetic domain by a change of polarization direction of reflected light of the light spot.

Abstract: In a signal reproducing apparatus, information is reproduced by moving a magnetic wall on a magnetic recording medium as follows. A temperature profiled is given the medium by using a light beam so as to detect a first reproduction signal h(t)=f(t)+.alpha.*f(t-.beta.) containing both a signal component f(t) obtained by a first backward magnetic wall movement toward a temperature peak position in the temperature profile and a signal component .alpha.*f(t-.beta.) obtained by a second forward magnetic wall movement toward the temperature peak position. The power of the light beam is adjusted so that a delay amount .beta. is essentially an integer multiple of a recording code channel interval Tb. An amplitude ratio .alpha. is detected. A slice level is set in accordance with the detected amplitude ratio .alpha. so as to reproduce the information by comparing the first reproduction signal with the slice level.