Abstract: In a CLV(constant linear velocity) or MCLV(substantially constant linear velocity)-type optical disk apparatus, instability of servo at inner and outer circumferences of an optical disk is prevented by adjusting a servo-loop gain of tracking servo control or focus servo control in accordance with the radial-direction position of an optical spot, i.e., in accordance with the rotation frequency of the optical disk.

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: An information recording and/or reproducing apparatus for recording data onto and/or reproducing data from a recording medium by irradiating a light beam emitted from a light source onto a desired track of the recording medium through an optical system. The apparatus includes (i) a single processor for executing an input/output control of the data for the apparatus and a servo process of the light beam such that the input/output control of the data and the servo process of the light beam are alternately switched at a predetermined period, and (ii) an actuator for moving the light beam on the basis of the servo process of the processor. The precision of the servo process is changed so that the precision is increased when an amount of an external disturbance is large.

Abstract: An information recording and/or reproducing method and apparatus for effecting recording of data onto and/or reproducing of data from a recording medium by irradiating a desired track on the recording medium with a light beam emitted from a light source through an optical system. In the apparatus, a single processor executes an input/output control of the data for the apparatus and a power control of the light beam by interrupting the input/output control at every predetermined period. The processor inhibits the interrupt power control of the light beam in accordance with a predetermined situation.

Abstract: An information recording and/or reproducing apparatus for recording data onto and/or reproducing data from a recording medium such as a magnetic disk, a magnetooptic disk, or the like by irradiating a laser beam emitted from a light source such as a semiconductor laser onto a desired track of the recording medium through an optical system, wherein the apparatus includes a single processor for executing an input/output control of data for the apparatus and a servo process of the laser beam by interrupting the servo process between the input/output control at every predetermined period. The processor switches a precision of the servo process in accordance with a predetermined situation such as a change in operating mode.

Abstract: An optical data recording/reproducing apparatus includes a light-receiving unit for receiving a light beam which has passed through or is reflected by a recording medium, the light-receiving unit having a plurality of light-receiving areas which are disposed such that they can perform wavefront splitting on the single light beam when the light-receiving areas receive the light beam, a data signal sensing unit for obtaining a data signal on the basis of an output of at least one of the plurality of light-receiving areas, and a servo signal sensing unit for obtaining a servo signal on the basis of an output of at least one of the plurality of light-receiving areas. The light-receiving area used to obtain the data signal and the light-receiving area used to obtain the servo signal are different from each other.

Abstract: A reproducing apparatus for reproducing a signal by moving a record bearing medium and a reproducing head relative to each other is provided with a time base corrector for correcting the time base of the signal reproduced. The time base corrector is characterized in that the operating state thereof is changed from one state over to another according to whether or not the controlled movement of the medium and the head relative to each other is in a steady state.

Abstract: An optical information recording and/or reproducing apparatus is arranged to record and/or reproduce information on or from a recording medium with a light beam. The apparatus includes a circuit for generating a focusing error signal of the light beam, a filter for filtering the focusing error signal, the attenuation factor of the filter being greater at a high frequency region, a circuit for selecting either a focusing error signal filtered by the filter or a focusing error signal not filtered by the filter in accordance with an operating mode of the apparatus, and a circuit for executing focusing control of the light beam, using the selected focusing error signal.

Abstract: Input/output processing of information is controlled in a magnetooptical disc apparatus for recording and/or reproducing the information on a magnetooptical recording medium by irradiating a desired track of the recording medium with a light beam via an optical system. The servo control of the light beam such as tracking servo control, focusing servo control or the like is performed by causing interruption in the input/output processing control. When the apparatus activates, a parameter in the servo control is set on the basis of a reproduction signal amplitude of the information with a change in state of the servo control and a parameter in signal processing of the information is set in accordance with a reproduction signal amplitude of the information corresponding to the set parameter for the servo control.

Abstract: An optical information processing apparatus and method of correcting an offset of a tracking error signal.

Abstract: An optical information processing apparatus includes an optical head for irradiating a light beam onto an optical recording medium, an objective lens, mounted on the optical head, for condensing the light beam onto the recording medium, a photodetector for receiving a light beam from the recording medium and for generating a tracking error signal indicative of a positional deviation between a light beam irradiated position and a track, a tracking actuator for moving the objective lens in a direction intersecting tracks of the recording medium, a tracking controller for driving the tracking actuator in accordance with the tracking error signal so as to correct the positional deviation, a position detector for detecting a relative position of the objective lens with respect to the optical head in the direction intersecting the tracks, a measuring device for measuring a relationship between an offset of the tracking error signal and a position of the objective lens from the tracking error signal and an output of

Abstract: An optical information processing apparatus includes a unit for scanning a track formed on an optical recording medium with a light beam, a tracking control unit for correcting a position shift between a radiation position of the light beam on the medium and the track, and an offset correction unit for automatically correcting an offset of the tracking control unit.

Abstract: An optical information processing apparatus includes a light source for radiating a light beam onto an optical information recording medium. A first photosensor is provided for partially receiving the light beam emitted from the light source and generating an output, and a second photosensor is provided for receiving either a light beam reflected by the recording medium or a light beam transmitted through the recording medium and generating an output. A control circuit controls power of the light beam emitted from the light source using the output from the first photosensor, and a correction circuit automatically corrects linearity of the output of the first photosensor with respect to the power of the light beam emitted from the light source in accordance with the output from the second photosensor.

Abstract: A reproducing apparatus for reproducing a signal by moving a record bearing medium and a reproducing head relative to each other is provided with a time base corrector for correcting the time base of the signal reproduced. The time base corrector is characterized in that the operating state thereof is changed from one state over to another according to whether or not the controlled movement of the medium and the head relative to each other is in a steady state.

Abstract: An optical information recording and/or reproducing apparatus includes an optical head for recording and/or reproducing information by applying a light beam to an optical recording medium having a plurality of tracks, an actuator for relatively moving the light beam in a direction which intersects the tracks, an optical detector for detecting, by intersecting the tracks, a reflected or transmitted light of the light beam, which has been modulated, a peak holding circuit for holding a peak value of a signal detected by the optical detector, a bottom holding circuit for holding a bottom value of the detected signal, a circuit for obtaining an intermediate value of the held peak value and bottom value, and a comparison circuit for transmitting an on-track/off-track signal by making a comparison between the intermediate value and the detected signal.

Abstract: A peak hold circuit for a gain control signal is disclosed for use with an apparatus for recording information on and/or reproducing information from an optical recording medium by scanning the optical recording medium with a condensed light beam.