Abstract: The optical disk player is capable of correctly restarting to write data. Data protection means returns an optical pick-up from an interruption address to a synchronization starting address. The data protection means reads data from the synchronization starting address to the interruption address at a reading velocity equal to a former writing velocity. The data protection means restarts writing data from the interruption address if a phase of data read is synchronized with a phase of data to be written. The data protection means returns the optical pick-up to the synchronization starting address and reads data from there to the interruption address at a reading velocity slower than the former writing velocity so as to synchronize the phases if the synchronization is failed.

Abstract: A method and device for recording information signals on a partly recorded writable record carrier (11), e.g. an optical disc. An information signal represents at least one information unit. The record carrier has a recording track which comprises preformed track position information indicative of locations for recording the information units. From the information signal a modulated signal is generated, and the recording track is scanned for recording the modulated signal. If recording is after and adjacent an existing recorded unit, linking information is read from an end boundary area of the existing recorded unit and used for logically generating the modulated signal. If recording is before and adjacent to an existing unit, linking information is read from a begin boundary area of the existing unit and thereafter used for logically generating the modulated signal.

Abstract: A magneto-optical recording medium includes a substrate and a reproducing layer and a recording layer provided on the substrate. A recording magnetic domain is provided in the recording layer by heating the recording layer by irradiation with light and applying a recording magnetic field to the recording layer so that information is recorded in the recording layer. The recording layer is a magnetic film having magnetic anisotropy in a direction perpendicular to the film surface, and the magnetic film holds the recording magnetic domain formed therein.

Abstract: A method and apparatus for constructing a file tree in a compact disc player from the file system of a compressed audio CD is disclosed. After determining the target sector for building the file tree of the CD player, the CD player reads into the memory of the CD player the target sector and a number of contiguous sectors following the target sector. After identifying a target sector, the CD player first determines if the target sector is cached in the memory of the CD player. If the target sector is cached in the memory of the CD player, the sector is retrieved from the CD player. If the target sector is not cached in the memory of the CD player, the target sector is retrieved from the file system of the CD, together with a number of sequential contiguous sectors following the target sector.

Abstract: The width and/or depth of guide grooves on the disc substrate surface are changed in each data recording layer and the guide groove depth of the recording film layer is appropriately shaped in each data recording layer to provide a high density, high recording capacity optical disc. The optical disc has plural substrate layers each having plural guide grooves; plural data recording layers laminated on the substrate layers, each of the plural data recording layers having a recording film for recording data over the guide grooves; and an intermediate layer between the plural data recording layers. The guide groove width is different on each substrate layer. The guide grooves of the data recording layers formed according to the guide grooves of the substrate layer have the same pitch in each data recording layer.

Abstract: Recording layer 12 is formed on substrate 11, ultraviolet-curing resin layer 13 is formed on recording layer 12, and light-transmissible layer 15 is attached to the ultraviolet-curing resin layer 13 through adhesive layer 14. It is preferable that the hardness of the ultraviolet-curing resin 13 is equal to HB or more, and the film thickness thereof is set to a value in the range from 2 ?m to 40 ?m. The total thickness of the ultraviolet-curing resin layer 13, the adhesive layer 14 and the light-transmissible layer 15 is set to a value in the range from 20 ?m to 150 ?m.

Abstract: System and methods are described for inhibiting the readability of an optical media due to changes in a pseudo-reflective material that composes the optical media after the optical media has been exposed to air for a predetermined time. An optical media includes a data encoded component. At least a fraction of the data encoded component transforms from a substantially optically reflective state to a substantially optically non-reflective state as at-least-in-part a function of time from an initializing event. The systems and methods provide advantages because of low cost, limited content lifetime, avoidance of rental returns and minimum changes to existing manufacturing processes.

Abstract: The present invention provides an optical disk device that reduces a track lead-in time associated with a seek time. A switching means 50 includes a multiplier A 11 for multiplying an output of a speed control means 5 by &agr; and a multiplier B 12 for multiplying an output of a position control means 6 by (1−&agr;), and an adder 13 for adding an output of the multiplier A 11 and an output of the multiplier B 12 to output a result of the addition as control input to an actuator driving means 8. At the time of movement of an optical pickup 3 toward a target track, the multiplier factor &agr; for the multipliers A 11 and B 12 is set at 0, thereby performing control of the actuator driving means 8 by means of the position control means 6.

Abstract: Data in the same signal format as a conventional CD is recorded to a first part of a record medium and compressed digital data in CD-ROM format in double density is recorded to a second part of the record medium. Addresses of a first session including the first part are represented in the notation of minute, second, and frame, and addresses of a second session including the second part are represented in binary notation. When the record position is moved from the first session to the second session, an end address of the first session is converted into an address of the second session. The start address is then designated and second addresses (for example, addresses represented in binary notation) are generated. When there is a non-record portion between the two sessions, an address value corresponding to the non-record portion is added to the start address. The resultant address is used as the new start address.

Abstract: There are provided an information recording medium which permits accurate tracking servo, and a method for recording and reproducing for an information recording medium which allows recording and reproducing of a signal at a favorable S/N by carrying out at least one of information recording and information reproduction while accurately performing tracking servo. A magneto-optic disk includes a magnetic recording layer for magnetically recording information. The magnetic recording layer is in advance magnetized for concentrically or spirally around the center of the disk in such a manner that magnetized regions are disposed such that adjacent regions are magnetized in different directions and alternately arranged in the radial direction of the disk. Accordingly, tracking can be continuously performed and accurate tracking servo can also be performed.

Abstract: A multilayer film including a first magnetic layer, a second magnetic layer, and a third magnetic layer in the stated order is formed so that a Curie temperature TC2 of the second magnetic layer is set to be lower than a Curie temperature TC1 of the first magnetic layer and a Curie temperature TC3 of the third magnetic layer and that the third magnetic layer is a perpendicular magnetization film. In at least a part of a region at a temperature lower than TC2, the first magnetic layer is perpendicularly magnetized by exchange coupling with the second magnetic layer, and the magnetization of the third magnetic layer is transferred to the first magnetic layer via the second magnetic layer because of the exchange coupling. The second magnetic layer is made of a magnetic layer that remains in an in-plane magnetization state at room temperature and is perpendicularly magnetized in a temperature range from a critical temperature TCR higher than room temperature to the Curie temperature TC2 of the same.

Abstract: This invention provides method and apparatus for controlling reproduction speed of an optical disk, which detects the magnitude of a disk vibration after initial operation of an optical disk and adjusts the disk rotation speed based upon the vibration magnitude. The method according to this invention comprises the steps of rotating an installed optical disk; detecting the quantity of signal derived from tracking error signals which are combined from signals reproduced from the optical disk when the rotation speed reaches to a predetermined speed; and deciding whether to increase the rotation speed above the predetermined speed based upon the detected quantity of the signal. This invention is able to reproduce an optical disk at the possible maximum speed within allowable speed limit through detecting accurate disk vibration magnitude at the initial operation stage and adjusting the reproduction speed to higher speed.

Abstract: When an LPP (land pre-pit) is formed between shallow grooves or shallow pits, the LPP is formed on a land existing between the shallow grooves or the shallow pits. Further, the LPP is formed in a position displaced from a centerline of the land in the radial direction by a predetermined amount. Furthermore, a laser beam power utilized for forming a shallow groove or a shallow pit adjacent to the LPP is reduced so as to be lower than a regular laser beam power.

Abstract: An optical disc discrimination apparatus and method which discriminate a type of a disc loaded on a DVD-RAM drive accurately and simply. The optical disc discrimination apparatus includes an RF envelope generator which detects an envelope signal from an RF signal read from a disc loaded in an optical disc recording and/or reproducing apparatus at an off-track state, when only a focusing is accomplished prior to performing a tracking control, an envelope amplitude detector which detects the amplitude of the detected envelope signal, and a disc discriminator which compares the amplitude of the detected envelope signal with predetermined reference level and discriminating whether the disc is a CD, a DVD-ROM, or a DVD-RAM, based on the comparison result. Thus, a type of the disc can be discriminated simply and accurately with a change in the amplitude of the RF signal.

Abstract: The present invention provides an optical recording medium, in which levels of wobble signals extracted from a recording area formed snakily, a reproduction exclusive area and an impossible area are maintained constant. On DVD-RW, groove tracks are snakily formed on a groove section on which recording information is recorded, and pit strings where a plurality of phase pits wave are arranged on the impossible area and the reproduction exclusive area which prevent illegal copying. On the respective areas, pit depths (groove depths), duty of the pit strings and wobbling amplitudes are set according to predetermined conditions so that the output levels of the wobble signals extracted based on the wobbling amplitudes can be maintained constant on the respective areas. As a result, synchronous control can be made accurately at the time of recording and reproduction on/from the DVD-RW.

Abstract: The present invention relates to a method, an apparatus and a record carrier for controlling radiation power and/or field strength during a reading operation from a magneto-optical recording medium comprising a storage layer and a read-out layer. An expanded domain leading to a pulse in a reading signal is generated in said read-out layer by copying a mark region from said storage layer to said read-out layer upon heating by said radiation power and by applying an external magnetic field. A pulse pattern in the reading signal is analyzed. The analyzing result is compared with run length characteristics of the data stored in said storage layer. The radiation power and/or the magnetic field strength are controlled on the basis of the comparison result. Thus, much less or no disc capacity has to be reserved for radiation power and/or magnetic field calibration, since the user data can be used for this purpose.

Abstract: An information playback apparatus which can perform random access playback, reverse playback, shuttle playback, etc. quickly and seamlessly. A signal processing unit stores audio data read out from a disc into a buffer memory, and performs information processing for audio playback based on the audio data in the buffer memory. Audio data of certain time durations respectively corresponding to a past and a future with respect to the audio data currently being subjected to audio playback is replenished and stored into the buffer memory. When a jog dial is manipulated, reverse playback, shuttle playback, etc. are performed quickly and seamlessly based on the audio data in the buffer memory.

Abstract: A ring buffer region is divided into a plurality of ring regions. Information is recorded in (or reproduced from) the ring regions from one end of the ring buffer region to the other end of the ring buffer region and from the other end to the one end in the predetermined order. The predetermined order is determined such that the recording (or reproducing) takes place skipping over at least one ring region every time.

Abstract: A storage medium for thermally-assisted magnetic recording has a recording layer which substantially parallel tracks for recording information. The recording layer includes a series of recording regions, each region comprising a plurality of tracks for magnetically recording information. The tracks in a region have a pitch p, and a region extends a distance ½ p beyond a centre line of the outermost track of the region. Neighbouring regions are separated from one another by magnetically non-recording areas having a width substantially equal to or larger than the pitch p. The writing of one region does not have thermal cross-talk on other regions.

Abstract: An optical disk includes a land and a groove. On this optical disk, data is recorded on both the land and the groove. A distance between the center of the land and the center of the groove adjacent to the land is 0.28 &mgr;m or more. The optical disk has a data efficiency of 80% or more. Thus, an optical disk having a storage capacity of 25 GB or more can be provided.