Sharp Kabushiki Kaisha Corporation

Shigeo Terashima

Toshihisa Deguchi

Hiroshi Fuji

Kunio Kojima

Shigemi Maeda

Takeshi Yamaguchi

Kenji Ohta

Hirotsugu Matoba

Tsuneo Fujiwara

Akira Takahashi

Masaru Nomura

Tomiyuki Numata

Noriaki Sakamoto

Kentaro Tsuji

Kentaroh Tsuji

Yoshihiro Sekimoto

Takashi Iwaki

Masahiro Horii

Junji Hirokane

Michinobu Mieda

Hideyoshi Yamaoka

Junichi Washo

Toshio Ishikawa

Takao Hyuga

Toshiyuki Tanaka

Tomoyuki Miyake

Kiyoshi Kumata

Jun Akiyama

Takaaki Okamoto

Syoichi Yasuda

Taizo Sasada

Kenrow Yatsunami

Masaaki Hanano

Yoshihiko Iwamoto

Kiyotsugu Amasaki

Shigema Maeda

Kazuaki Okumura

Hiroshige Hirashima

Grooves and lands are provided to a magneto-optical disk so as to be alternately arranged, and recording bit strings are formed on the grooves and lands respectively so that information is recorded. Moreover, pit rows are formed on boundary sections between the adjoining grooves and lands so that address information of a recording/reproducing track is recorded, and the pit rows are formed every other boundary section. When the grooves and the lands are scanned as the recording/reproducing track by a light, an address of the recording/reproducing track is read out from the pit rows, and successively, discrimination is made whether the recording/reproducing track which is scanned by an optical spot is the groove or the land. This prevents crosstalk which causes inclusion of address information in the next pit rows, thereby, making it possible to obtain accurate address information. Moreover, since a total number of formed pit rows can be decreased and accuracy in a shape of pits is relieved, an optical recording medium can be easily produced.

Optical recording medium having pit rows

A magneto-optical disk including a transparent substrate, pit strings containing information formed in spiral or concentric form on a surface of the transparent substrate, a magneto-optical recording medium layer for covering the surface of the transparent substrate having the pit strings formed thereon, and magneto-optical recording areas formed by spiral or concentric flat portions between adjacent pit strings. An optical pickup for reproducing pit information and magneto-optically-recorded information from the magneto-optical disk. A magneto-optical disk drive for recording and reproducing information on the magneto-optical disk. The magneto-optical disk has a memory capacity which is twice the memory capacity of a conventional magneto-optical disk having ROM, and is accessed at high speeds.

Magneto-optical disk, optical pickup, and magneto-optical disk drive

A magneto-optical recording device includes a magnetic field generating coil for generating a magnetic field on a magneto-optical recording medium, a power source for supplying a current to the magnetic field generating coil, switching circuit for driving said magnetic field generating coil to supply the current from the power source in the positive and negative directions by alternately forming first and second current paths according to recording information, first correcting circuit which is disposed on the first current path for correcting a transient response of the current amplitude in the positive direction caused by the magnetic field generating coil, and second correcting circuit which is provided on the second current path for correcting a transient response of the current amplitude in the negative direction caused by the magnetic field generating coil.

Magneto-optical recording apparatus having transient response correction

Optical recording medium having pit rows on every other boundary and

The present invention is provided with a disturbance observer which outputs a compensating signal for compensating a driving signal of a linear motor in accordance with (1) an output signal of an acceleration sensor unit which mechanically detects an acceleration of the linear motor, the acceleration moving the optical pickup, and (2) the driving signal of the linear motor. A high pass filter which has a low frequency band cutoff frequency substantially same as that of the acceleration sensor unit is also provided on the path which is formed by connecting the input of the driving signal to the generated compensating signal in the disturbance observer. With the high pass filter, it is possible to prevent the linear motor from being driven too sensitively or too greatly by the disturbance observer due to the driving signal, vibrations, or shocks applied from outside, or noises from the acceleration sensor unit or the circuits, thereby avoiding the danger that the linear motor or the optical pickup is damaged.

Device for controlling the motor of a recording and reproducing apparatus

In an information regenerating apparatus, recorded data constructed of a sector mark and a following header section having a plurality of data sets each having a pull-in pattern, an address mark and address information, is read out to form a regenerative signal which in turn is used to regenerate information. A phase-locked loop circuit in a signal synchronizing circuit, performs phase-synchronization with a regenerative signal at two different pull-in speeds. A speed indicating circuit, based on the counting of the number of clock pulses from a reference clock signal from a time of the generation of a sector mark detection signal showing the detection of the sector mark as a reference point, instructs the phase-locked loop circuit to set up a fast response speed every time the pull-in pattern appears on the regenerative signal, and instructs the phase-locked loop circuit to set up a slow response speed every time the pull-in pattern disappears from the regenerative signal.

Information regenerating apparatus

A magneto-optical memory apparatus for enhancing the recording density of a magneto-optical recording medium, thereby to increase its recording capacity. The magneto-optical recording medium having recording marks, each having two ends in which information is recorded. The apparatus also includes an optical head arranged such that at the time of recording onto the magneto-optical recording medium, the recording marks are recorded such that the ends of each recording mark correspond to a second code of digital information composed of two different types of codes; at the time of reproduction, a light beam having a condensing spot is projected to the magneto-optical recording medium and, when a reproduction light containing reproduction information is entered to the optical head from the magneto-optical recording medium, a reproduction signal is supplied; and when the light beam is projected to a recording mark, an information pulse corresponding to the second code is generated in the reproduction signal, only when the reproduction light from the recording mark interferes with the reproduction light from the non-marking part; and a signal detector circuit for detecting the information pulse in the reproduction signal obtained from the optical head and for converting the reproduction signal into a digital reproduction signal.

Magneto-optical memory apparatus utilizing edges or recording mark to

An information recording and reproducing device uses a recording medium which is provided with units composed of blocks and a unit information recording area which includes unit allocation information, sector number information indicating the number of sectors per unit and unit number information identifying each unit. When the recording medium is placed in the device, the respective information is read by a calculating unit which calculates physical sector numbers corresponding to a block specified for recording and reproduction operations. Access operations are performed to the calculated sectors, which allows the desired information to be recorded. The block includes dummy sectors which are added before and after each group of predetermined numbers of effective sectors. When high-volume information is recorded over several blocks, the dummy sectors may be provided only for the first and last blocks. The device records a group of information whose volume varies from the smallest block number toward the larger block numbers, while it records a group of information whose volume is fixed from the largest block number. Thus, the recording area is effectively used. The device easily conducts the information management when a host device specifies a block. The file management may be executed by providing a unit for recording file management information separately from a unit for recording files.

Method and apparatus for recording and reproducing information in black

A recording and reproducing device, which records and reproduces information on and from a rewritable recording medium having absolute addresses and including an information recording area wherein information entered from external devices is recorded and a Table of Contents area wherein additional address information with respect to the information recorded in the information recording area is recorded. The TOC area contains the absolute addresses of the recording positions of each information recorded in the information recording area. A display section graphically and independently displays the recorded and unrecorded ranges of the information recording area according to the absolute addresses recorded in the TOC area with respect to the recording positions of each piece of information. A warning device alerts the user that a position on the disc is occupied by referring TOC area when it is instructed to record new information in the position of the information recording area where another information has already been recorded.

Method and device for data management in optical recording medium

A disk recording and reproducing device records and reproduces information on and from a magneto-optical disk having 3 3 and there is TOC (Table of Contents) area. Additional information with respect to each piece of the information recorded in the information recording area is recorded in the TOC. The device includes operation keys, a TOC memory for storing read/write control information for desired pieces of information entered through the operation keys. There is an optical head and a magnetic coil for recording, in the TOC area, the contents stored in the TOC memory as additional information. A controller controls the read/write operation to the disk according to the read/write control information. With the arrangement, a user can recognize necessary/unnecessary information and defective parts in the disk, and therefore make effective use thereof as well as maintaining secrecy of the information.

Disk recording and reproducing device

A recording/reproducing device for recording and reproducing on a rewritable recording medium which comprises absolute addresses, a sound information recording region for recording sound information entered thereto from outside and a TOC area for recording additional information on the sound information recorded in the sound information recording region. The device includes an optical head as well as a magnetic coil for recording silencing information or fading information in the TOC area, each of which respectively specifies that a desired range in the sound information recording region should be erased or a fade-in/fade-out operation adjacent to the recording start/end position of desired sound information should be executed in reproducing sound information in the sound information region, a TOC memory wherein the silencing information or the fading information read from the TOC area is stored when the recording medium is placed in the device, and a muting circuit which performs the silencing operation within the range specified by the silencing information stored in the TOC memory or a fading circuit which performs the fade-in/fade-out operation according to the fading information stored in the TOC memory.

Recording/reproducing device

An information recording and reproducing device having an automatic gain control device wherein its amplification degree is adjusted according to an AGC voltage varying with an amplitude of a reproduced signal. The automatic gain control device has a holding circuit which holds the AGC voltage in each of recording and erasing operations, and also holds the AGC voltage in reproducing an un-recorded area of information. The AGC voltage is also used for determining an optimum recording condition for a recording medium. Instead of the holding circuit, by installing a limiter circuit for limiting an amplitude of a reproduced signal, and by the use of transient response of the reproduced signal due to an coupling situated before the limiter circuit, an appropriate amplification degree can also be obtained in the automatic gain control device. Further, the limiter circuit which is disposed at a stage before a reproduction circuit and also before a capacitor having the ac coupling, may restrain influence of the transient response of the ac coupling given on the reproduced signal, thereby making it possible to reproduce a signal with small amplitude immediately after recording or erasing operation.

Information recording and reproducing device with reproduction and

In the optical recording element of the invention, alignments of long thin pits inclined in various directions with respect to the track direction are formed on the tracks and information is recorded therein according to the different inclines of the pits, thereby performing higher-density and larger-volume recording without reducing the spacing between each pit and the track pitch. The invention also discloses an optical data retrieval system for use with the above optical recording element, which scans the pit alignments with a laser beam spot, detects the inclines of the pits by obtaining the distribution of the intensity of reflected light which is caused by light diffraction at the pits, and plays back information in accordance with the inclines. Therefore, not only can the substantially same structure as that of a standard type optical data retrieval system be applied to the invention without making any complicated change, but also cross-talk is less likely to be produced in the read out signals.

Optical retrieval system for encoding pit angular data and optical

An information recording and reproducing device has a first recording clock generation circuit which generates a clock based on pre-recorded information on a magneto-optical disk, a second recording clock generation circuit and a switching circuit The switching circuit selects a first recording clock when recording information is of discrete information and selects a second recording clock when recording information is of successive information. Moreover, in the present device, a first reading clock is used as well as a second clock as a clock for reading out the reproduced data from the magneto-optical disk, which had been once stored in memory. The second reading clock having a reference frequency is generated by a second clock generation circuit and is used for reading out successive information such as music information. The first reading clock in synchronization with the reproduced signal is generated by a first reading clock generation circuit and is used for reading out discrete information such as computer-use data. In addition, in the case of discrete information, it is possible to start recording/reproducing operation immediately after an optical head reaches a desired position, thereby permitting to shorten an access time.

Information recording and reproducing device providing faster access

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Tenri, Japan

Shigeo Terashima