Abstract: A disk medium, an information recording device, and an information reproducing device are provided, which are capable of efficiently recording sub-information such as security data and, if the sub-information is set as the security information, enhancing a security performance. The disk is divided into a plurality of zones in radial directions. A logical zone count in each zone is obtained by dividing a total recordable frame count in each zone by a frame count in a unit logical zone.

Abstract: A magnetic domain of a predetermined length is formed on a magneto-optical recording medium with the phase difference altered between the rise of a laser drive signal to generate a pulsed laser beam and the fall of a magnetic head drive signal to generate a magnetic field. A phase difference optimization circuit detects an optimum phase difference corresponding to the lowest error rate from the error rate of a reproduced signal obtained by reproducing the formed magnetic domain. A magnetic head drive signal is newly generated to produce a magnetic field modulated according to a record signal based on the detected optimum phase difference. According to the generated magnetic head drive signal and the first laser drive signal, a magnetic field is applied to the magneto-optical recording medium, and a pulsed laser is directed onto the magneto-optical recording medium to record a signal.

Abstract: There is provided an optical disk drive capable of appropriately effecting recording and reproducing operations without being affected by offset values and a laser output value, which are set at startup of the disk drive, even when changes have arisen in the internal temperature of the disk drive because of changes in ambient temperature. In an optical disk drive, a temperature sensor provided on a pickup measures a temperature. When changes in temperature are greater than a predetermined level, a focus offset value, a tracking offset value, and a value of laser output from the pickup are reset.

Abstract: A magneto-optical record medium and a reproducing apparatus for the same allow data reproduction having good characteristics by a simple structure. The magneto-optical record medium includes a plurality of first grooves (3) each having sidewalls, at least one of which is wobbled in accordance with address information; an address mark (21) formed by changing a width of a land located between second grooves connected to the first grooves; and third grooves wobbled cyclically, formed in a data portion magnetically storing data and connected to the second grooves. The reproducing apparatus reproduces the data from the magneto-optical record medium.

Abstract: A magnetic head which can apply magnetic fields in opposite directions from each other within a beam spot formed on a magneto-optical disk. This magnetic head includes two cores located in close proximity and two coils. The level of the magneto-optical signal output from the optical head becomes greater as a function of deviation of the center of the magnetic head from the center of the laser beam. Therefore, the magnetic head is moved in the tracking direction or the track direction so that the level of the magneto-optical signal becomes 0.

Abstract: A magneto-optical record medium and a reproducing apparatus for the same allow data reproduction having good characteristics by a simple structure. The magneto-optical record medium includes a plurality of first grooves (3) each having sidewalls, at least one of which is wobbled in accordance with address information; an address mark (21) formed by changing a width of a land located between second grooves connected to the first grooves; and third grooves wobbled cyclically, formed in a data portion magnetically storing data and connected to the second grooves. The reproducing apparatus reproduces the data from the magneto-optical record medium.

Abstract: A magneto-optical head includes an optical member, objective lens, SIL and coil. The magneto-optical head converts a laser beam to an evanescent light and directs it to a magneto-optical recording medium. Further, the magneto-optical head applies a magnetic field to the magneto-optical recording medium. When tilt is caused, it decreases the tilt angle. The optical member refracts the laser beam to a prescribed direction to be directed to the objective lens when the laser beam is displaced from a designed optical axis. The objective lens allows the laser beam to be focused onto a point on an end face of the SIL. Further, the SIL emits the evanescent light. The optical member is arranged in contact with the optical member. As a result, a signal can accurately be recorded or reproduced even when tilt is caused to an optical disk while alleviating the problem associated with the tilt.