Sanyo Electric Co., Ltd.

Kenji Torazawa

Satoshi Sumi

Toshiaki Hioki

Yoshiharu Uchihara

Kenji Nakao

Noboru Mamiya

Kenji Asano

Yoshihiro Hori

Kenji Tanase

Seiji Kajiyama

Yoshihisa Suzuki

Hisashi Matsuyama

Kouichi Tada

Youichi Tsuchiya

Atsushi Yamaguchi

Seiichiro Takahashi

Masahiro Higuchi

Akiomi Kunisa

Nobuo Itoh

Takanari Kusafuka

Shigeki Hori

Seiji Murata

Hiroshi Watanabe

Katsutoshi Hibino

Shigekazu Minechika

Seizo Kato

Youichiro Goto

Yasuhiro Ishii

Sayoko Tanaka

Tateo Toyama

Nagatoshi Sugihara

Michiaki Sato

Yasuko Teragaki

Shin'ichiro Tomisawa

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

The present invention provides a recording medium and an information recording/reproducing apparatus which permit recording and/or reproducing by a laser beam of optimized power for each recording medium. The recording medium is provided with a calibration region in addition to an information recording region. The calibration region has wobbles formed such that the amplitude of the waveform of a reproduced signal therefrom can change. Prior to recording to the information recording region, a signal is recorded in the calibration region by changing the laser power, and the recorded signal is immediately reproduced. The waveform of the reproduced signal is evaluated to determine optimum laser power for recording. At the time of reproducing, a signal previously recorded in the calibration region is reproduced while changing the laser power, and laser power optimum for reproducing is determined.

Information recording/reproducing apparatus

Micro-pits or micro-pit strings, which are disabled precise copying by means of illegal copying described above and enable signals different from signals of a normal disc to be detected in case of failure in precise copying, are recorded in a copy protected area of an optical disc beforehand. A read unit checks the copy protected area and determines a loaded disc is legal disc or illegally copied disc. If illegal, reading is prohibitted.

Optical recording disc capable of preventing illegal copy

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

A table having a plurality of recording densities and a plurality of recording/reproducing conditions corresponding to the recording densities and each necessary for recording/reproducing a signal at a corresponding recording density is recorded in a TOC region of a magneto-optical disk. A recording/reproducing apparatus finds out a recording density at which it can record/reproduce data from the table and records or reproduces a signal at the recording density. The recording/reproducing conditions include the wavelength of a semiconductor laser, whether or not to employ the optical pulse magnetic field modulation recording method, the presence/absence of an optical super resolution pickup, whether or not to employ the optical pulse reproducing method, whether or not to employ the PRML method and the like. Therefore, if the recording/reproducing technology further advances, a signal may be recorded/reproduced to/from the magneto-optical disk at an optimum recording density without having to change the data format of the magneto-optical disk.

Storage medium recorded with recording/reproducing conditions depending upon recording densities and method of recording and reproducing therefor

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

An illegal disc copying protection system which includes an optical disc with recorded information as a series of pits aligned to a track direction from the optical disc, a recording system which records information as a series of pits aligned to the track direction from the optical disc, and a reading system which reads information being recorded as a series of pits aligned to the track direction from the optical disc.

A magneto-optic disk and a recording/reproduction device therefor adopt optical super-resolution to increase recording capacity. More specifically, the magneto-optic disk has an heat emitting layer (,) on a recording layer (,) and still preferably has an intermediate layer (,) between a reproduction layer (,) and the recording layer (,). The recording/reproduction device includes a circuit (,) for pulsing a laser beam to be radiated to the magneto-optic disk and still preferably includes a polarization rotating unit (,) and a polarizing filter (,) for blocking only the center of the laser beam in reproduction. The heat emitting layer (,) diffusing any heat generated by the laser beam, and the discontinuously radiated laser beam allow small recording domain. The laser beam having its center blocked forms smaller main lobe due to diffraction effect.

Recording and reproduction device for a magneto-optic recording medium capable of recording information according to optical super-resolution

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

A light guide plate is provided including a first lens portion comprising a plurality of recessed or projected lenticular unit lenses formed of the same resin as that of the light guide plate on a light emission surface. The plurality of lenticular unit lenses in the first lens portion are triangular prism portions whose respective vertexes have an angle of 125.degree. to 165.degree. and are so arranged that their respective ridge lines are nearly parallel to each other. Such construction makes it possible to set the number of lenticular lens sheets used to one or to further eliminate the necessity of the lenticular lens sheets, so that the cost of parts and the fabrication cost of the light guide plate can be reduced. A second lens portion may be provided on a light reflective surface opposite to the light emission surface on which the first lens portion is disposed, the second lens portion including a plurality of recessed or projected lenticular unit lenses formed of the same resin as that of the light guide plate. Alternatively, a light guide plate is provided having a plurality of grooves with approximately equal groove widths formed on a surface opposite to a light emission surface, the grooves being arranged substantially parallel to each other and the spacing between the grooves narrowing as the distance from the light incident surface increases, with the spacing from the far end of one of the plurality of grooves proximate to the light incident surface to the near end of a groove adjacent thereto farther away from the light incident surface being 5 to 15 times the groove width.

Light guide plate and surface light source using the light guide plate

A disc is provided which includes a disc body of disc shape having a center hole. An information recording area is formed on one side surface of the disc body. The information recording area has information thereon read by reflection of laser light. The information recording area has an inner circumferential edge positioned adjacent to the center hole. The disc body has a radius ranging from 39 mm to 80 mm, the center hole has a radius ranging from 7.5 mm to 7.55 mm, and the inner circumferential edge of the information recording area being positioned to extend from a radius of 15 mm to 22 mm from the center of the disc body. A disc may be manufactured by variations of the following disc manufacturing method including the steps of: supporting a stamper on a first mold by a supporting means; defining a forming space by clamping the first mold to a second mold; defining a center hole of the disc by advancing a center hole defining member into a center part of the forming space; connecting a injection means into the forming space by opening a gate member of a resin injection member and filling the forming space with a resin through a communicating hole from the injection means; and cooling the resin in the forming space after shutting off connection between the injection means and the forming space by closing the gate member of the resin injection member.

Optical disc manufacturing apparatus

The present invention is provided with a cartridge holder for installation of a cartridge which houses an optical disk, and a tray which is located below said cartridge holder and in which an unhoused optical disk is placed, and which can move to-and-fro between a position in which information are recorded and/or played back and a position in which the optical disk is exchanged, a center shaft which rotates by means of a rotating drive means, and a holding mechanism including a turntable which is secured to the shaft and is provided with a magnetic body, an optical disk centering means and a support surface which supports the optical disk; and a clamper which can be brought into contact with and separated from the support surface of said turntable and which maintains in contact with the support surface of the turntable optical disks which do not have hubs. The optical information recording/playback device allows installation of a variety of optical information recording media such as optical disk with or without hubs and optical disks which are housed in a cartridge or unhoused.

Optical disk recording/playback device with means to recognize, read

A disc recording/reproducing apparatus according to the present invention intermittently records and reproduces compressed digital audio data in normal recording/reproduction. In high-speed dubbing of digital audio data, two of such apparatuses are used, wherein compressed digital audio data is continuously reproduced from a disc for reproduction by the reproduction side apparatus to be directly applied to the recording side apparatus and continuously recorded on a disc for recording. Thus, the compressed high-speed dubbing of the digital audio data can be achieved without increasing a rotation speed of the disc even in high-speed dubbing.

Audio data recording/reproducing apparatus having digital high-speed

An erasing beam B1 and a recording beam B2 emitted from a laser diode array 20 are focused on different tracks of a optical magnetic disk D, the erasing beam B1 being focused on a track located ahead of a track on which the recording beam B2 is focused. The reflected beams of the erasing beam B1 and the recording beam B2 are separated respectively into two polarized components by means of a polarized beam splitter 17 and the polarized components are received by photo sensor means 23 and 24. Based on outputs of the photo sensor means 23 and 24, an address signal, a focus error signal and a tracking error signal are obtained. At the time of reproduction, the laser diode array 20 emits a reproducing beam so that the photo sensor means provide a reproducing signal.

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Ogaki, Japan

Kenji Torazawa