Sanyo Electric Co., Ltd.

Sanyo Optec Design Co., Ltd.

Kenji Asano

Toshiaki Hioki

Satoshi Sumi

Noboru Mamiya

Kenji Torazawa

Yoshiharu Uchihara

Hideaki Yano

Yoshihiro Hori

Kenji Nakao

Hisashi Matsuyama

Seiichiro Takahashi

Akiomi Kunisa

Nobuo Itoh

Shigeki Hori

Hiroshi Watanabe

Kenji Nagatomi

Kenji Tanase

Kazushi Mori

Yoshihisa Suzuki

Naoyuki Takagi

Koichi Tada

Katsutoshi Hibino

Shigekazu Minechika

Tadashi Okajima

Yasuyuki Kano

Sayoko Tanaka

Keiji Nagata

Takanori Kishida

Hideharu Baba

Yoshihiro Aoi

Shogo Suzuki

Ichizo Sakamoto

A lens fixing device includes a lens holder having a lens (lens area) made of a resin, and a mounting portion. The lens holder has two projections. Each of the two projections is formed with a guide surface and a mounted surface. A line of intersection of an extension of the guide surface of the projections and an extension of the mounted surface of the projections in a plane direction is aligned with an optical axis of the lens area. The lens holder is positioned with respect to a plane direction orthogonal to the optical axis by contact of the guide surfaces with receiving surfaces of the mounting portion. The lens holder is fixedly attached by an adhesive.

Lens fixing device and optical pickup device

A temperature sensor is disposed in an optical pickup to detect a temperature of an objective lens. An optical element (for example, a collimator lens) is driven according to a temperature change of the objective lens, which corrects deterioration of an optical characteristic of a laser beam passing through the objective lens. Good recording/reproduction is smoothly performed even if the optical characteristic of the objective lens is changed with the temperature change.

Optical disk apparatus and optical pickup device

A diffraction element is disposed between a beam branching element (such as a beam splitter) and a photodetector. The diffraction element further segment an interference fringe introduced into stray light by a diffraction grating which divides a laser beam emitted from a laser beam source into a main beam and two sub-beams.

Optical pickup device

The invention provides a disk playback device wherein a disk () is irradiated with a laser beam from an optical head () to reproduce signals from the disk, and which comprises an external synchronizing signal producing circuit () and a delay circuit () for producing a reproduction synchronizing signal providing reference timing at which a reproduced signal is detected by reading an output signal from the optical head (), a circuit () for detecting the reproduced signal by reading the output signal from the optical head () based on the reproduction synchronizing signal, and a system controller () for determining an optimum phase for a normal reproduction operation by altering the phase of the reproduction synchronizing signal and executing a reproduction operation, the controller () being operable to make a phase adjustment for the reproduction synchronizing signal prepared by the delay circuit (). A normal reproduction operation can be performed at all times by assuring the reproduction synchronizing signal of the optimum phase.

Disk reproduction device

A disc apparatus () includes an optical lens (). A laser beam is irradiated onto a recording surface of the magneto-optical disc () through the optical lens (), and a TE signal or an RF signal is detected on the basis of the laser beam reflected by the recording surface. Herein, an MPU () replaces the optical lens () in an optical axis direction, and a TE signal detection circuit () or an RF signal detection circuit () detects the TE signal or the RF signal at each of lens positions. A laser power is adjusted by the MPU () such that amplitude of each of the TE signal or the RF signal detected is below a saturation value. When a parameter is adjusted, a position of the optical lens () is controlled such that the amplitude of the TE signal or the RF signal detected thereafter is maximized.

Disc apparatus for reproducing a signal on a disc using a laser beam

A disk recording-playback device including a laser drive circuit for feeding a drive signal to an optical head and adjusting the power of a laser beam irradiated by the optical head, an error correcting circuit for detecting an error rate of a reproduced signal, and a system controller for controlling operation of the laser drive circuit for signal reproduction and signal recording based on the output of the error correcting circuit. The system controller successively sets the laser powers to at least three different values, obtains evaluation data for each laser power, approximates the relationships between the laser powers and the evaluation data to a quadratic curve, whereby an optimum laser power is derived corresponding to a vertex of the quadratic curve. Accordingly the optimum reproduction power and recording power are set, to thereby record and reproduce signals with high accuracy.

Disk recording-playback device

The present invention provides a disk playback device comprising a laser drive circuitfor feeding a drive signal to an optical headand adjusting the power of a laser beam irradiated by the optical head, an error correcting circuitfor detecting an error rate of a reproduced signal, and a system controllerfor controlling operation of the laser drive circuit for signal reproduction and signal recording based on the output of the error correction circuit. The system controllerretrieves one limit value of two limit values of a reproduction power wherein the error rate is not beyond a prescribed value, and calculates an optimum reproduction power based on the one limit value retrieved. Accordingly it is possible to move to signal reproduction in a short period of time and to reproduce signals with high accuracy by setting the optimum reproduction power.

Disk playback device

A magneto-optical record medium and a reproducing apparatus for the same allow data reproduction having good characteristics by a simple structure. The magneto-optical record medium includes a plurality of first grooves ( ) each having sidewalls, at least one of which is wobbled in accordance with address information; an address mark ( ) formed by changing a width of a land located between second grooves connected to the first grooves; and third grooves wobbled cyclically, formed in a data portion magnetically storing data and connected to the second grooves. The reproducing apparatus reproduces the data from the magneto-optical record medium.

Record medium and reproducing apparatus of the same for detecting an offset correction

Information reproduction apparatus of the present invention is directed to realize data reproduction properly and reliably from an optical disk, including a wobble detection circuit ( ) to detect a wobble signal read out by an optical head ( ), a PLL circuit ( ) to frequency-multiply the wobble signal to generate a synchronizing signal (SS ), a delay circuit ( ) delaying a synchronizing signal (SS ) sequentially to generate a plurality of synchronizing signals (SS -SS ) of different phases, a particular pattern detection circuit ( ) to detect a particular pattern in a reproduced signal, and a switching unit ( ) to select one synchronizing signal having a phase difference preset by a preset circuit ( ) with respect to a detected particular pattern and supplying the selected synchronizing signal to a laser drive circuit ( ) and to a signal demodulation circuit ( ).

Information reproduction apparatus, information recording apparatus, and reference mark detection circuit

An magneto-optical disc recording/reproducing apparatus includes an optical head ( ) to detect a wobble ( ) and an address mark ( to ) in an magneto-optical disc ( ) and output a wobble signal (WB , WB ) and an address mark signal (AML, AMG), a PLL circuit ( ) to generate a clock signal (CK) in response to wobble signal (WB ), an address mark synchronous signal generation circuit ( ) to generate an address mark synchronous signal (AM) in response to address mark signal (AML, AMG), a synchronizing circuit ( ) to synchronize clock signal (CK) with address mark synchronous signal (AM) and generate a synchronized clock signal (SCK), and a timing setting circuit ( ) to generate a timing pulse signal (TG ) to control a magnetic head driving circuit ( ) and a timing pulse signal (TG ) to control a laser driving circuit ( ). The recording/reproducing apparatus can detect a address mark ( to ), record la data signal on magneto-optical disc ( ) in synchronization with the detected address mark, and reproduce a data signal from magneto-optical disc ( ) in synchronization with the detected address mark, so that the data signal can be surely recorded/reproduced.

Information recording/reproducing apparatus to record/reproduce information on a recording medium recorded with an address mark

Information reproducer, information recorder and reference mark detection circuit

A meandering groove is formed in a digital disk (,) with a wobble signal that is wobbled to reproduce a clock signal. The wobble signal is read out by an optical head (,). An address detection circuit (,) detects an address signal that is multiplexed with the wobble signal. A PLL oscillation circuit (,) provides a clock signal in synchronization with the wobble signal. Data is modulated by a modulation circuit (,) according to the clock signal and a timing signal based on the address signal, and recorded on the digital disk (,). In reproduction, a RF signal in the wobble signal is converted into a digital signal by an A/D converter (,). The signal is demodulated by a demodulation circuit (,) for data output.

Digital disk recording and reproduction apparatus

Digital recording method, digital disk, digital disk recording device, and digital disk reproducing device

Growing community of inventors

Kakamigahara, Japan

Kenji Asano