Hitachi, Ltd.

Hitachi Media Electronics Co., Ltd.

Hitachi-lg Data Storage, Inc.

Fumio Isshiki

Takeshi Shimano

Sumio Hosaka

Nobuyuki Maeda

Takuya Matsumoto

Takahiro Kurokawa

Kunikazu Ohnishi

Yoshinori Ishikawa

Masakazu Sugaya

Hideki Maruyama

Masahiro Yamaoka

Tatsundo Suzuki

Motoyuki Suzuki

Masafumi Mochizuki

Tetsuya Nishida

Taku Hoshizawa

Shinji Fujita

Takayuki Ichihara

Takeyoshi Kataoka

Koichi Hirose

Katsuhiko Izumi

Hiromitsu Mori

Atsuko Kuroda

The amplitude deviation of a tracking error signal in an optical disk apparatus is reliably corrected by processing signals at low costs. A servo signal generator generates a tracking error signal and a lens error signal from a photodetected signal. A lens error deviation signal memory circuit stores the lens error signal generated at the servo signal generator, and reproduces the one-turn deviation of the lens error signal. A tracking error signal corrector learns an amplitude correcting value for the tracking error signal from the tracking error signal detected in reproducing the one-turn deviation of the lens error signal, and stores the amplitude correcting value in a correcting signal generator.

Optical disk apparatus

An optical disk apparatus includes an optical pickup and a signal processor. The optical pickup includes an actuator for driving an objective lens, and a detected light intensity signal output part for outputting a detected light intensity signal to the processor. The signal processor includes a servo signal generator for generating a main push-pull signal and a sub push-pull signal on the basis of the detected light intensity signal supplied from the detected light intensity signal output part, a signal generator for generating a differential push-pull signal and a lens error signal by conducting addition/subtraction on the main push-pull signal and the sub push-pull signal, and a tracking offset correction signal generator which is input with the lens error signal to output a tracking offset correction signal. The differential push-pull signal correction is conducted by conducting addition/subtraction between the differential push-pull signal and the tracking offset correction signal.

In an optical disk apparatus, an optical pickup includes an actuator for driving an object lens, and a sensed signal output part for making it possible to generate a tracking error signal and a lens error signal by addition/subtraction, and a signal processor includes a servo signal generator for generating a tracking error signal and a lens error signal on the basis of a signal supplied from the sensed signal output part, and a tracking offset correction quantity signal generator supplied with the lens error signal to output a tracking offset correction quantity signal. DC (direct current) offset correction is conducted by conducting addition/subtraction between the tracking error signal and both the lens error signal and the tracking offset correction quantity signal.

A rewritable optical disk apparatus, optical information recording and reproducing apparatus or the like is allowed to automatically and properly adjust the optical system to the optimum focal condition regardless of the readout signal detector's positional error and the residual aberration in the optical system. The spherical aberration and defocus are coarsely adjusted using the amplitude (PP amplitude) of the tracking error signal and then finely adjusted using the amplitude (RF amplitude) of the readout signal. Since the spherical aberration can properly be adjusted, it is possible to raise the reliability of the readout signal.

Optical information recording apparatus

In an optical disk apparatus having an exclusive RF detector plane mounted therefore, as a method of obtaining a synthesized readout signal based on band-synthesis is used in order to obtain a readout signal having a good S/N ratio, a waveform distortion easily caused by a delay time difference or a sensitivity difference in the playback at higher speeds can be prevented. In order to correct the delay time difference or a sensitivity error in two channels of RF signals to be band-synthesized according to the selection of the sensitivity or playback speed, a delay time controller, a sensitivity controller, and a selector for selecting a combination method are engaged. An information holder for such control or selection is also provided.

Optical pickup and optical information reproduction system

Provided are an optical pick up and an optical component used for the optical pickup which are capable of preventing or restraining occurrence of deviation and unbalance which are caused by assembly errors during manufacturing of optical components, a temperature variation or the like. The optical pickup comprises a laser, a polarization changeover element for changing over a direction of polarization of an optical beam emitted from the laser, a beam splitting element for splitting the laser beam into a plurality of optical paths in accordance with a direction of a polarization, a plurality of objective lenses for focusing laser beams onto a recording layer of the optical disc, a rise-up mirror, and a plurality of coupling lenses arranged respectively intermediate of the plurality of optical paths led to the plurality of objective lenses. The rise-up mirror is arranged intermediate of the plurality of optical paths led to the plurality of objective lenses and adapted to be used common to respective optical beams on the plurality of optical paths. The plurality of the coupling lenses are coupled to and held on one and the same drive portion.

Optical disc drive, optical pickup and optical component used therefor

An operation mode is arranged to be switched between in recording/reproducing and in adjustment. A switching circuit with a hold circuit therefor is on a light receiving element including an optical pickup having a laser light source emitting a laser beam, an objective lens focusing the laser beam onto a recording layer of a disc, and a light receiving element receiving an optical signal modulated. The light receiving element is operable in an adjustment mode for selecting of the signal of an individual light-receiving surface and for outputting the same. The light receiving element is configured so that the address selection signal line in the adjustment mode may be used also as a sensitivity switching signal line. A compact and highly reliable optical pickup with less signal lines can be provided.

Optical pickup and optical disk driving apparatus using the same

In an information reproducing apparatus in which a liquid crystal lens element is used for the selection and switching of layers, the instability of servo control during the switching of the layers due to the overlapping of signals from two layers is eliminated and the focal point is shifted onto the correct switched layer. During the switching of the liquid crystal lens, a focus bias is added depending on the direction in which the layers are switched so as to stabilize servo control. Alternatively, the objective lens is held during the switching and after the switching of the liquid crystal lens element, the hold state is released in synchronization with the rotation of the disk.

Information reproducing apparatus

An indirect semiconductor laser having an indirect semiconductor used as the material of an active layer is used, instead of a conventional direct semiconductor laser so as to obtain a reproducing optical source, in order to reduce optical interference noise of the laser caused in the optical head in an optical disc apparatus, and to eliminate the necessity of high frequency wave convolution, thereby it is possible to reduce the cost.

Optical disc drive apparatus with an indirect semiconductor laser containing an asymmetric quantum well structure

There is provided an optical disc recording/reproduction device capable of accurately performing the focus offset and spherical aberration correction even for an optical disc having no data recorded. The optical disc recording/reproduction device includes: an optical pickup having a spherical aberration corrector for correcting the spherical aberration of an objective lens; and various control units; and can generate a tracking error signal (TE) at least by a push-pull signal by the push-pull method. When an optical disc mounted is in an unrecorded state, the spherical aberration correction amount and the objective lens focus offset amount are adjusted according to the push-pull signal, predetermined data is recorded on the optical disc, and the reproduction signal obtained by the data is used to adjust the spherical aberration correction amount in the spherical aberration corrector of the optical pickup and the focus offset amount of the objective lens.

Optical disc recording/reproduction device

Even in an optical disk which includes, within a single disk, plural record areas whose track-pitches differ from each other, a tracking parameter is adjusted in a short time and with a high accuracy. At first, an optical pickup for reading information recorded in the optical disk is displaced into a reference track-pitch area which is one of the plural record areas of the optical disk. Moreover, the tracking gain is adjusted so that the tracking servo gain in this area may exhibit a predetermined characteristic. Also, the value thus acquired is recorded into, e.g., a non-volatile memory. After that, based on the tracking parameter learned/adjusted in the reference track-pitch area, the tracking parameter in another track-pitch area is calculated using the track-pitch ratio therebetween. Thereby it becomes possible to adjust the tracking parameter in a short time and with a high accuracy.

Tracking learning/adjusting method and optical disk device

A method and an optical disk apparatus that can accurately and stably correct the spherical aberration even for a blank write-once optical disk and can detect a spherical aberration error signal with a simple construction of parts in real time. In a blank write-once disk, the tracking servo is switched to an inoperative state, push-pull signals from outputs of the photodetectorare detected in a state of 'in focus' and in a state of 'out focus,' respectively, by a push-pull signal generation circuit, and.the amplitudes of these push-pull signals are subjected to difference calculation in a spherical aberration error detectorto obtain a spherical aberration error signal A. Then, the spherical aberration is corrected with this spherical aberration error signal A, and subsequently a specific pattern signal is recorded in a trial writing area, this signal is reproduced in the state of &#x201c;in focus&#x201d; and in the state of &#x201c;out focus,&#x201d; respectively, the amplitude of each reproduced signal is acquired by a reproduced signal generation circuit, these amplitudes are subjected to difference calculation in the spherical aberration error detectorto obtain a spherical aberration error signal B. The spherical aberration is corrected with this.

Optical disk apparatus and method for recording and reproducing an optical disk

A high recording-density and highly reliable optical disc according to the two-dimensional PRML system is provided in which periodic signal fluctuations in the readout signal caused by an overall positional displacement of pits between adjacent tracks can be detected at each sampling clock timing and can be tracked and compensated. Two-dimensional inter-symbol interference is compensated during the production and recording of the pattern of the medium. The readout signal is compensated by a process of multi-value tracking before symbols are extracted from the signal.

Information recording medium, information reproducing method, and information reproducing apparatus

A vertical magnetic recording apparatus is provided which can diminish thermal decay of magnetization to ensure a high reliability of the life of recorded information and which can stably effect the write of magnetic information. Light assist is performed by obliquely applying light to a gap between a main pole of a vertical recording head and a medium. The light is radiated from the head side of the apparatus with respect to the medium. Utilizing the present invention, the thermal decay of magnetization at room temperature is diminished, the life of the recorded information is increased, and the storage reliability of the disk is increased.

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Yokohama, Japan

Fumio Isshiki