Abstract: An optical disk apparatus comprising means for moving a focal point of a light beam for reproducing information recorded on an information face of a disk, in the direction perpendicular to the information face; means for detecting a reflected light from the disk; and means for discriminating whether the disk set in the apparatus is a disk having a thick base substrate or a disk having a thin base substrate. In this apparatus, a maximum value AS1L.sub.max of an output signal from the reflected light detecting means and a maximum value ENV.sub.max of an amplitude of an information reproducing signal are detected while driving the focal point moving means so that the focal point passes through the information face, and the discriminating means discriminates whether the disk set in the apparatus is a disk having a thick base substrate or a disk having a thin base substrate, on the basis of the ratio of ENV.sub.max to AS1L.sub.max.

Abstract: The optical recording medium of this invention includes: a first substrate having a first information surface; a semitransparent reflection film formed on the first information surface of the first substrate; a second substrate having a second information surface; a reflection film formed on the second information surface of the second substrate; and an adhesive layer for adhering the first substrate and the second substrate so that the first information surface and the second information surface face each other, wherein the thickness of the first substrate is 0.56 mm or more, the thickness of the adhesive layer is 30 .mu.m or more, and the total thickness of the first substrate and the adhesive layer is 0.68 mm or less.

Abstract: The operating and other procedures of an optical disk application system of the type for which a network is used are simplified. Optical disks have auxiliary data recording areas, where different IDs for individual disks, and/or cipher keys and/or decoding keys for ciphers are recorded in advance in a factory. By using the IDs to release the soft ciphers, using the cipher keys when sending the ciphers, and using the decoding keys when receiving the ciphers, user authorization procedures are simplified.

Abstract: An optical information recording and/or erasing system is provided. This system includes a servo control circuit for feedback-controlling an optical system to compensate for focusing and tracking errors during record and reproduce modes of operation. For compensating for misalignment of an optical spot formed by the optical system falls on a recording medium, the offset is applied to a servo control signal. During a preselected period of time following application of the offset required for completing the servo control, information-recording or erasing operation is inhibited. Thus, fine recording conditions are faithfully established from a leading edge of a recording portion of the recording medium.

Abstract: The optical recording medium of this invention includes: a first substrate having a first information surface; a semitransparent reflection film formed on the first information surface of the first substrate; a second substrate having a second information surface; a reflection film formed on the second information surface of the second substrate; and an adhesive layer for adhering the first substrate and the second substrate so that the first information surface and the second information surface face each other, wherein the thickness of the first substrate is 0.56 mm or more, the thickness of the adhesive layer is 30 .mu.m or more, and the total thickness of the first substrate and the adhesive layer is 0.68 mm or less.

Abstract: An optical disk apparatus comprises a focusing means for focusing a light beam on a recording medium having first and second information faces; means for moving a focal point of the light beam in a direction substantially perpendicular to the information faces of the recording medium; means for detecting a focus condition of the light beam on the basis of an output signal from the reflected light detecting means; a focus control means for driving the focal point moving means on the basis of an output signal from the focus condition detecting means, and controlling the light beam so that the focus condition of the light beam becomes a prescribed focus condition; and a focus jumping means for moving the focal point of the light beam from the first information face to the second information face by driving the focal point moving means.

Abstract: The tilt control apparatus of the invention controls to minimize an error in an orthogonal relationship between an optical disk and an optical axis of a light beam irradiated onto the optical disk.

Abstract: The optical recording medium of this invention includes: a first substrate having a first information surface; a semitransparent reflection film formed on the first information surface of the first substrate; a second substrate having a second information surface; a reflection film formed on the second information surface of the second substrate; and an adhesive layer for adhering the first substrate and the second substrate so that the first information surface and the second information surface face each other, wherein the thickness of the first substrate is 0.56 mm or more, the thickness of the adhesive layer is 30 .mu.m or more, and the total thickness of the first substrate and the adhesive layer is 0.68 mm or less.

Abstract: An optical record carrier and methods and apparatuses for recording and reproducing an information on and from said optical recording carrier, whereby the effects of crosstalk from adjacent tracks is reduced, and stable tracing control is possible, is achieved. A recording track to which information divided into sector units is recorded is formed in a spiral or concentric pattern on the surface of the optical record carrier. Each sector further comprises sixty frames. Each frame comprises a re-sync pattern, frame address, data, and postamble fields. Identification information identifying the sector location of the information is recorded to the data block of the first frame. The user data is recorded after the data is scrambled using a value generated by a fifteen-stage maximum-length sequence generator based on the value of this identification information.

Abstract: An optical information recording medium includes a track storing information in a plurality of sectors, wherein the track is formed spirally or concentrically. One sector includes a plurality of frames and one frame includes a resync mark region, a frame address region, an information region, and a postamble region. In the information region in the first frame, identification information for identifying the position of the sector is stored. In the information region in each frame, information obtained as a result of scrambling performed based on a value of the identification information is stored.

Abstract: An optical disk apparatus comprising a device for moving a focal point of a light beam for reproducing information recorded on an information face of a disk, in the direction perpendicular to the information face; a device for detecting a reflected light from the disk; and a device for discriminating whether the disk set in the apparatus is a disk having a thick base substrate or a disk having a thin base substrate. In this apparatus, a maximum value AS1L.sub.max of an output signal from the reflected light detecting device and a maximum value ENV.sub.max of an amplitude of an information reproducing signal are detected while driving the focal point moving device so that the focal point passes through the information face, and the discriminating device discriminates whether the disk set in the apparatus is a disk having a thick base substrate or a disk having a thin base substrate, on the basis of the ratio of ENV.sub.max to AS1L.sub.max.

Abstract: A disk-shaped recording medium includes a plurality of first tracks and a plurality of second tracks for recording data, the first track and the second track being alternately arranged in the radial direction on the surface of the recording medium in one of a pattern of concentric circles and a spiral pattern; a plurality of first servo areas and a plurality of second servo areas discretely located at a plurality of respective specified rotation angular positions of the surface along the circumferential direction of the recording medium; and a plurality of first servo marks and a plurality of second servo marks used for tracking control. The first servo marks are provided in the first servo areas along each of the first tracks, and the servo marks are provided in the second servo areas along each of the second tracks.

Abstract: The tilt control apparatus of the invention controls to minimize an error in an orthogonal relationship between an optical disk and an optical axis of a light beam irradiated onto the optical dick.

Abstract: An optical information recording medium includes a track storing information in a plurality of sectors, wherein the track is formed spirally or concentrically. One sector includes a plurality of frames and one frame includes a resync mark region, a frame address region, an information region, and a postamble region. In the information region in the first frame, identification information for identifying the position of the sector is stored. In the information region in each frame, information obtained as a result of scrambling performed based on a value of the identification information is stored.

Abstract: A phase error between an information signal including a reference signal that can be detected asynchronously and a synchronized signal that is synchronously produced from the information signal is detected, and a signal in response to an absolute value of the phase error is produced. Further, a defect detecting signal is produced in response to the absolute value of the phase error. Therefore, whether a pulse signal exceeding a maximum value of the pulse width of the information signal, that is, a pulse signal exceeding the pulse width of the reference signal, is detected or not, it is possible to detect that the signal reproduction enters a defect region immediately after the entry. Accordingly, a defect with noise or a track jumping can be detected rapidly.

Abstract: An optical record carrier and methods and apparatuses for recording and reproducing an information on and from said optical recording carrier, whereby the effects of crosstalk from adjacent tracks is reduced, and stable tracing control is possible, is achieved. A recording track to which information divided into sector units is recorded is formed in a spiral or concentric pattern on the surface of the optical record carrier. Each sector further comprises sixty frames. Each frame comprises a re-sync pattern, frame address, data, and postamble fields. Identification information identifying the sector location of the information is recorded to the data block of the first frame. The user data is recorded after the data is scrambled using a value generated by a fifteen-stage maximum-length sequence generator based on the value of this identification information.

Abstract: The optical recording medium of this invention includes: a first substrate having a first information surface; a semitransparent reflection film formed on the first information surface of the first substrate; a second substrate having a second information surface; a reflection film formed on the second information surface of the second substrate; and an adhesive layer for adhering the first substrate and the second substrate so that the first information surface and the second information surface face each other, wherein the thickness of the first substrate is 0.56 mm or more, the thickness of the adhesive layer is 30 .mu.m or more, and the total thickness of the first substrate and the adhesive layer is 0.68 mm or less.

Abstract: A tracking control device for controlling a position of a beam spot formed by converging a light beam on a disk having tracks formed thereon includes: an actuator for moving the beam spot in a direction substantially perpendicular to the tracks; a tracking error detecting circuit for detecting a deviation of the beam spot from one of the tracks using the light beam returning from the disk and for outputting a tracking error signal indicative of the detected deviation; and a control circuit section for outputting a driving signal to drive the actuator in accordance with the tracking error signal so as to control the beam spot to be positioned on the one of the tracks. When the driving signal is saturated, the control circuit section obtains a saturation signal in accordance with an amount of the saturation, delays the saturation signal, and supplies the saturation signal to the actuator together with the driving signal.

Abstract: A read-out information signal read out from an optical disk carrier is digitized, thereby detecting an amplitude of an absolute value of a phase error between the read-out information signal and a synchronized clock signal. The synchronized clock signal is obtained by using a phase locked loop constituted by a phase detector having two outputs, that is, a phase lead and a phase lag, and a VCO operating at an average value of a differential signal representing a difference between the two outputs. A phase error amplitude is detected from a sum signal representing a sum of the two outputs of this phase detector. By appropriately displacing a focus actuator in a state where a focus control is performed, an offset compensation amount where the phase error amplitude becomes minimum is obtained.

Abstract: A method and apparatus for jumping from an initial track to a target track on a medium having tracks of alternating polarity uses a combination of two-track and one-track jumps to jump to the target track. Detection of the jump middle-point for a two-track jump includes detecting a zero crossing in a tracking error signal. Detection of the jump middle-point for a one-track jump includes detecting a zero-crossing in a differential signal generated according to the tracking error signal. A target track several tracks away may be reached using consecutive two-track jumps, and if necessary, a single one-track jump.