Abstract: An optical reproduction apparatus in accordance with the present invention has a gain control circuit for controlling a gain of an amplifier circuit which amplifies a reproduction signal in accordance with amplitudes of the reproduction signal from an optical recording medium. The amplitude is sent to a power control calculation circuit which controls the reproduction power of a light beam in accordance with the amplitude. The gain control circuit has a slower response speed than that of the power control circuit at least during a period when the power control circuit controls the reproduction power. This allows to provide an optical reproduction apparatus that can realize the stable reproduction power and automatic gain control even to the unevenness of the amplitudes of the reproduction signal.

Abstract: An optical disc and an optical disc drive for the optical disc are provided which are suitable for recording data with a high density. The optical disc D uses both lands and grooves as recording tracks. Each of the tracks consists of one address segment and forty five data segments. The address segment is wobbled at one side thereof. Each of the data segments is a DC groove. The address segment records an address information including a sync signal, frame address, track address and CRC, a tilt pattern and a clock mark. The clock mark is adapted to reflect laser beam in one amount before the mark and in another amount after the mark. The tilt pattern has a different track pitch from those in other areas. The data segments record data magneto-optically.

Abstract: A disk type recording medium has spiral or concentric grooves that are divided into a plurality of zones 1, 2 and 3 in the radial direction of the disk. Physical address information and sector boundary information are recorded by groove wobbling. Records of data are arranged on grooves with reference to sector boundary information on the condition that a wobble frequency of physical address information obtainable when rotating the disk at a constant angular velocity is constant within a unit zone and increases with each change of zones from inner to outer peripheral zone on the disk.

Abstract: A magneto-optical information recording/reproducing apparatus in which a magneto-optical information recording medium at least including a first magnetic film having perpendicular magnetic anisotropy, and a second magnetic film to which information recorded on the first magnetic film is transferred by irradiation of a laser beam, is used so that a readout laser beam is irradiated onto the second magnetic film to thereby readout the information transferred to the second magnetic film. The apparatus includes a 2-split detection circuit for receiving the readout laser beam reflected from the second magnetic film of the recording medium, and a subtraction circuit in which output signals of the two detection elements of the 2-split detection circuit are subtracted from each other to generate a differential signal.

Abstract: A method and apparatus are provided for optimally controlling the width of recording marks formed by a light beam on an optical recording medium in an optical recording apparatus. The method is accomplished by selecting and storing in a storage device a predetermined optimal read signal value, and then setting a plurality of selectable predetermined recording conditions in the optical recording apparatus. These conditions differ from one another in the quantity of light in the light beam, or in the strength of an external magnetic field. In the optical recording apparatus, a set of first test patterns then are recorded by the light beam on separate first tracks of the optical recording medium under each of the predetermined conditions. Similarly, a second test track is recorded onto the optical recording medium under the same predetermined conditions adjacent to each of the first test tracks.

Abstract: An optical memory element includes a guide track groove portion and address signal pit portion for indicating the address of the guide track groove. The address signal pit portion has a pit width narrower than the groove width of the guide track groove portion.

Abstract: A disk type recording medium and a disk recording and reproducing device for use in constant linear velocity and zone constant angular velocity systems wherein the disk type recording medium has spiral or concentric grooves that are divided into a plurality of zones in the radial direction of the disk. Physical address information and sector boundary information are recorded by groove wobbling. Records of data are arranged on grooves with reference to sector boundary information on the condition that a wobble frequency of physical address information obtainable when rotating the disk at a constant angular velocity is constant within a unit zone and increases with each change of zones from inner to outer peripheral zones on the disk.

Abstract: A disk-shaped recording medium has a groove only one of whose side-walls wobbles or deviates in radial directions of the disk in order to prerecord first address information. In addition, the disk medium has block areas in the groove and in the land where the first address information is given and sector areas provided with second address information for every piece of recording data which is divided into predetermined lengths, wherein `m` pieces of sector areas are allocated for `n` pieces of block areas and recorded in the groove and the land (both n and m are integral numbers, and n is smaller than m). The second address information based on the first address information enables the sectors to be set at any length, and improves reliability of the address information. Moreover, the second address information realizes high density recording using both the land and the groove.

Abstract: A disk-shaped recording medium has a groove only one of whose side-walls wobbles or deviates in radial directions of the disk in order to prerecord first address information. In addition, the disk medium has block areas in the groove and in the land where the first address information is given and sector areas provided with second address information for every piece of recording data which is divided into predetermined lengths, wherein `m` pieces of sector areas are allocated for `n` pieces of block areas and recorded in the groove and the land (both n and m are integral numbers, and n is smaller than m). The second address information based on the first address information enables the sectors to be set at any length, and improves reliability of the address information. Moreover, the second address information realizes high density recording using both the land and the groove.

Abstract: An optical memory element includes a guide track groove portion and address signal pit portion for indicating the address of the guide track groove. The address signal pit portion has a pit width narrower than the groove width of the guide track groove portion.

Abstract: A method is provided for manufacturing a magneto-optical memory element having guide grooves for storing information. The method includes applying a laser beam onto a resist film material located on a substrate to produce guide track grooves and address signal pits. Thereafter the resist film is developed. The remaining resist film is removed and a magnetic medium layer is deposited on the substrate.

Abstract: An information recording and reproduction apparatus uses a recording medium that contains information which prohibits digital copying. A reproduction section reproduces the desired informatiion stored on a first recording medium. A recording section records the reproduced output at a desired position on a second recording medium. However, an erasing section erases the information from the first recording medium during the process of recording that information on the second recording medium. The first and/or second recording medium cannot be removed from the information recording and reproduction apparatus until the erasing operation is completed.

Abstract: Pieces of leading compressed information, each of which corresponds to a predetermined number of blocks of each of a plurality of programs recorded on an optical disk, are successively read therefrom, and stored in a buffer memory in a compressed state as they are. Upon reproducing a certain program, the corresponding leading compressed information is read from the buffer memory, and reproduced after having been subjected to a decompressing process in an information-decompression processing circuit. The program is continuously reproduced by reading compressed information corresponding to the predetermined number of blocks following the leading compressed information from the optical disk and supplying the compressed information to the buffer memory. With this arrangement, it is possible to eliminate a slow switching operation in the case when programs are switched to start reproducing a different program.

Abstract: A data recording and reproducing apparatus uses a rewriteable optical disk with pre-recorded absolute address information, and comprises a data compression circuit for dividing and compressing continuous digital data into compressed plural data blocks, an expansion circuit to restore the compressed data to the original expanded form, and a buffer memory. Data is compressed in discrete data blocks and is recorded sequentially block by block to the optical disk. The compressed data is likewise read block by block from the disk during data reproduction. Using the data expansion circuit to expand the compressed data one block at a time, the data recording and reproducing apparatus can reproduce the original continuous digital data stream. Plural continuous digital data selections can thus be reproduced by alternately fetching data for the plural selections from the disk in compressed data block units and temporarily storing the data to a buffer memory for expansion.

Abstract: 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.

Abstract: An information reproducing apparatus has (1) a reference signal generating circuit for generating a first reference signal corresponding to reproduced signal of the main information; (2) a first switching circuit for selecting one of the reproduced signal and the first reference signal; and (3) a controller, which generates a selection instructing signal, for controlling such that the reproduced signal is selected during reproducing of the main information recorded area while the first reference signal is selected during reproducing of the main information unrecorded area. With the arrangement, when the main information unrecorded area is reproduced, the clock for carrying out the reproducing of main information is synchronized with the first reference signal which corresponds to the reproduced signal.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A data recording/reproducing apparatus uses a single recording medium in which absolute address data are previously formed. Also, the data recording/reproducing apparatus has a first memory for recording and a second memory for reproducing. Audio data reproduced from the recording medium is stored in the second memory at a first transfer rate, and the audio data stored in the second memory is sequentially read at a second transfer rate lower than the first transfer rate to be audio-reproduced, while audio data inputted from external is sequentially stored in the first memory at the second rate and the audio data stored in the first memory is read at the first transfer rate to be recorded on the recording medium. The aforementioned reproducing and recording operations are alternately repeated. Thus, the data recording/reproducing apparatus allows audio data recording operation to be concurrently performed during audio reproduction with the single recording medium.