Matsushita Electric Industrial Co., Ltd.

Yasuaki Edahiro

Mitsurou Moriya

Katsuya Watanabe

Kouichi Takamine

Shin-Ichi Yamada

Hiromichi Ishibashi

Takeharu Yamamoto

Shin-ichi Yamada

Mitsuro Moriya

Ryusuke Horibe

Akira Kurahashi

Hiroyuki Yamaguchi

Toshiyuki Shimada

Yasuki Matsumoto

Noboru Kikuchi

Kazuhiro Aoki

Masayuki Shibano

Hiroyuki Miyachi

Motoyuki Kobayashi

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 AS L of an output signal from the reflected light detecting device and a maximum value ENV 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 to AS L . Therefore, it is possible to discriminate between a DVD having a thin base substrate and a CD having a thick base substrate.

Optical disk apparatus

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.

Digital data reproducing apparatus and reproduction signal binarization level correcting method

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 AS,L,of an output signal from the reflected light detecting device and a maximum value ENV,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,to AS,L,. Therefore, it is possible to discriminate between a DVD having a thin base substrate and a CD having a thick base substrate.

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.

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. Therefore, even when the diameter or the mass of the disk varies or the characteristics of the spindle motor or the driving circuit vary, undesired reverse rotation of the disk due to over-deceleration or undesired increase in the time required to stop the disk is avoided. As a result, the rotation of the disk can be stopped with high reliability.

Disk rotation control apparatus with deceleration means

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. Therefore, it is possible to discriminate between a DVD having a thin base substrate and a CD having a thick base substrate.

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.

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. The tilt control apparatus includes: an optical pickup for irradiating the light beam onto the optical disk, thereby reproducing information recorded on the optical disk; an orthogonality error detector for outputting an orthogonality error signal corresponding to the error in the orthogonal relationship between the optical disk and the optical axis; a tilting mechanism for tilting the optical axis; a tilt controller for controlling such that the optical disk falls at right angles with the optical axis by driving the tilting mechanism in response to the orthogonality error signal; a pulse width variation detector for outputting a pulse width variation signal corresponding to a variation in a pulse width of an information reproduced signal obtained from the optical pickup; and a target value variable circuit for varying a control target value of the tilt controller based on the pulse width variation signal.

Tilt control apparatus with tilt target value based on bit error rate

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. Therefore, it is possible to discriminate between a DVD having a thin base substrate and a CD having a thick base substrate.

Optical disk thickness discriminating apparatus

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. The tilt control apparatus includes: an optical pickup for irradiating the light beam onto the optical disk, thereby reproducing information recorded on the optical disk; an orthogonality error detector for outputting an orthogonality error signal corresponding to the error in the orthogonal relationship between the optical disk and the optical axis; a tilting mechanism for tilting the optical axis; a tilt controller for controlling such that the optical disk falls at right angles with the optical axis by driving the tilting mechanism in response to the orthogonality error signal; a pulse width variation detector for outputting a pulse width variation signal corresponding to a variation in a pulse width of an information reproduced signal obtained from the optical pickup; and a target value variable circuit for varying a control target value of the tilt controller based on the pulse width variation signal.

Tilt control apparatus based on pulsed width detection of an information

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. Furthermore, an information transition interval of the information signal is measured for a prescribed period of time, and the defect detecting signal is terminated in response to a measured value of a time length of the reference signal that is detected in the prescribed period of time, in other words, the passing of the signal reproduction through the defect region is detected with reference to the synchronization of the reference signal. Therefore, pseudo locking of a PLL is avoided when it is operated again, and the PLL can be accurately re-locked.

Optical disk device

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.

Control devices for optical disk based on driving signal saturation

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.

Tracking control apparatus for correcting tracking error signal

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.

Control apparatus for tracking a light beam on a track of an optical

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.

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Osaka-fu, Japan

Yasuaki Edahiro