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 AS1Lmax of an output signal from the reflected light detecting device and a maximum value ENVmax 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 ENVmax to AS1Lmax.

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 AS1Lmax of an output signal from the reflected light detecting device and a maximum value ENVmax 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 ENVmax to AS1Lmax.

Abstract: The present invention has an objective of providing a digital data reproduction apparatus and a method for correcting a reproduced signal digitization level in which the signal quality of a reproduced signal from a recording medium is kept high while ensuring the reproduction stability. The digital data reproduction apparatus includes: reproduced signal digitization means for digitizing a reproduced signal; synchronization means for producing a clock whose phase is synchronized with a leading edge and a trailing edge of the digitized signal produced by the reproduced signal digitization means; and jitter detection means for integrating and thereby converting absolute values of phase errors between the digitized signal and the clock to a voltage value. The apparatus further includes digitization level correction means for correcting a reproduced signal digitization level so as to minimize a signal produced by the jitter detection means.

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 AS1Lmax of an output signal from the reflected light detecting device and a maximum value ENVmax 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 ENVmax to AS1Lmax.

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 reflected light from 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: A disk rotation control apparatus includes a spindle motor for rotating a disk, a rotational speed detecting device for detecting the rotational speed of the spindle motor, a signal generating device for generating an acceleration signal that accelerates the rotation of the spindle motor and a deceleration signal that decelerates the rotation of the spindle motor. A storage device for rotating the spindle motor with an acceleration signal generated by the signal generating device, measures a rise time required to reach a prescribed rotational speed &ohgr;1 while detecting the rotational speed of the spindle motor by the rotational speed detecting device, and stores the measured rise time. A control device for decides a time to generate the deceleration signal in the signal generating device on the basis of the rise time stored in the storage device, and stops the rotation of the spindle motor by applying the deceleration signal to the spindle motor.

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: 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: 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: 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: 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: 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: In a tracking control apparatus, a tracking error signal having a level of a positional shift of a beam of light projected through an optical head onto a recording medium is detected based on a reflected light from the recording medium, and the optical head is controlled so that a beam of light scans on the track to be recorded or reproduced based on the tracking error signal. Offset values of the tracking error signal on adjustment tracks which are predetermined among a plurality of tracks of the recording medium are detected, and then coefficients of a predetermined approximate equation approximately representing an offset value characteristic on the track based on the detected offset values are calculated. Further, an offset value corresponding to the track to be recorded or reproduced is calculated based on the first approximate equation with the calculated coefficients, and an offset value of the tracking error signal is corrected based on the calculated offset value.

Abstract: A tracking control apparatus is disclosed, in which a light beam is focused on an optical recording medium to form a light spot thereon, and a tracking error signal corresponding to a maximum or minimum point of total reflected light from a portion of the optical recording medium, which is irradiated by the light spot, is detected and used as a desired value for tracking servo control, whereby accurate tracking servo control can be made without producing any offset even when the surface of the optical recording medium is inclined or the optical axis of the light reflected from the optical recording medium deviates from a proper direction.

Abstract: In a photoelectric conversion amplifier for converting a light signal into a voltage signal, a resistor and a capacitor connected in parallel are provided between a non-inverted input terminal of a differential amplifier and a reference voltage source terminal, and thereby an offset voltage of the differential amplifier is eliminated and a frequency characteristic is improved to have a wideband.

Abstract: An optical recording and playback device for irradiating a light beam spot on a track of a data carrying medium at a target condition includes a servo error signal detector for detecting a deviation, such as defocus amount or off-tracking amount, of the light beam spot from the target condition. A servo circuit defining a servo loop with the servo error signal detector is provided for generating drive signals for driving actuators which control the movement of the light beam generator. A reference signal generator generates a reference signal to the servo loop. A complex amplitude calculation is carried out for calculating a complex amplitude of the frequency component of the reference signal applied to the servo loop. From the complex amplitude of the previously stored reference signal, a gain characteristics of the servo loop and a servo loop phase are calculated. An adjustment circuits are provided for changing the gain characteristics of the servo loop and the servo loop phase.

Abstract: A tracking control apparatus of an optical signal recording/reproduction apparatus, records and reproduces a data signal by causing a light spot focused on an optical recording medium to trace data-recording tracks and then accesses the light spot to a desired track. The tracking control apparatus varies a tracking-servo target value in a direction of performing the track-jumping operation, and then, if the tracking error signal exceeds a predetermined position level, the tracking control apparatus repeatedly varies the polarity of the tracking error signal until the light spot eventually arrives at the target track subject to the track-jumping operation. By virtue of the structure mentioned above, the tracking control apparatus can stably perform the track-jumping operation even when external disturbances, such as vibration, occur in the servo system.

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 reflected light from the recording medium; means for detecting a focus condition of the light beam on the basis on 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.