Abstract: An optical recording medium includes a first half-disc and a second half-disc. The first half-disc includes a substrate and an information layer (including a reflective layer) formed on a first side of the substrate. The second half-disc is bonded by an adhesive to a second side of the substrate of the first half-disc. In addition, a cover layer is formed over the first reflective layer. The cover layer has a thickness of approximately 0.1 mm. The substrate of the first half-disc has a thickness in a range of 0.3 mm to 1.0 mm. The first and second half-discs together have a combined thickness in a range of 0.8 mm to 1.3 mm.

Abstract: A method and an optical storage medium are provided for storing data to and accessing data from an embedded virtual medium within the optical storage medium. Information describing the embedded virtual medium may be stored on to the optical storage medium. Space for an embedded lead-in area of the embedded virtual medium, as well as user data for the embedded virtual medium, may be allocated within a data zone of the optical medium. A spare sector bitmap may be included in a lead-an area of the optical medium indicating spare sectors within the embedded virtual medium as being unavailable. A spare sector bitmap may be included within the embedded virtual medium indicating available spare sectors of the embedded virtual medium. Physical sector/logical block mapping of the optical storage medium may be modified for accessing data stored on the embedded virtual medium.

Abstract: In an information recording medium in which storage capacity per recording layer has increased so much that the size of an SBM varies with those of spare areas, there is mutual dependence between a DDS and an SBM and it is difficult to retrieve disc management information as intended. In an information recording medium according to the present invention, if the largest space is allocated to an user data area, the number of blocks to store a space bitmap is Ni (where Ni?2). But if the smallest space is allocated to the user data area, the number of blocks to use is smaller than Ni.

Abstract: A method of recording, and an apparatus for recording, data on a write-once disc, and the write-once disc used with the method and the apparatus. The write-once disc includes a plurality of update areas in which to record a predetermined type of updated information, at least one main access information area (AIA) in which to record main access information (AI), the main AI indicating a final update area in which finally updated information is recorded, among the plurality of update areas, and at least one sub AIA in which to record sub AI, the sub AI indicating a location of the finally updated information recorded in the final update area.

Abstract: A recording medium on which a recording/reproducing unit block is recorded, an apparatus to record and/or reproduce data on/from the recording medium, and a method of recording/reproducing the data on/from the recording medium. The recording/reproducing unit block comprises invalid data used in disc certification, and an identifier to indicate that the invalid data is included in the recording/reproducing unit block, the invalid data being used during the disc certification on a portion of the recording medium or the entire recording medium.

Abstract: An optical recording medium including recording and reading layers and a servo layer increases the recording capacity thereof. In the optical recording medium including the plurality of recording and reading layers and the servo layer, the servo layer has a groove and a land that can be used to perform tracking control with a long-wavelength servo beam. Information is recorded on the recording and reading layers with a recording and reading beam having a wavelength shorter than the wavelength of the servo beam. Recording marks are formed on the recording and reading layers while both the groove and land are tracked.

Abstract: In a multilayer optical recording medium, it is an object to suppress generation of crosstalk while reducing an interlayer distance of recording and reading layers. In an optical recording medium including three or more recording and reading layers, a first distance, and a second distance greater than the first distance by 3 ?m or more are alternately defined as interlayer distances of recording and reading layers.

Abstract: An optical recording and reading method is provided in which the information necessary for recording and reading layers is quickly acquired to reduce the seek time during reading and recording. The optical recording and reading method is used for an optical recording medium that includes a plurality of recording and reading layers and a servo layer. Information is recorded on or read from the recording and reading layers by irradiating them with a recording and reading beam while the servo layer is irradiated with a servo beam to perform tracking control. When information is recorded on the recording and reading layers, control information necessary for subsequent recording and reading to be performed on the recording and reading layers is recorded on the servo layer 18. When the subsequent recording or reading is performed, the control information on the servo layer is consulted, and then the recording or reading is performed on the recording and reading layers.

Abstract: Efficient recording and reading are achieved in an optical recording medium including servo layers and recording and reading layers. The optical recording medium includes: a first servo layer having a projection and a depression for tracking control that are formed in a first spiral direction; a second servo layer having a projection and a depression for tracking control that are formed in a second spiral direction opposite to the first spiral direction; and a plurality of recording and reading layers having a flat structure with no projection and depression for tracking control. Information is recorded on each of the plurality of recording and reading layers while tracking control is performed using the first servo layer or the second servo layer.

Abstract: An optical disk recording method includes the steps of: providing a multi-pulse chain from a recording wave; independently changing the pulse rise timing and pulse fall timing (pulse width) of the first pulse in the multi-pulse chain in accordance with a preceding space length and a recording mark length; changing the pulse rise timing and pulse fall timing (pulse width) in accordance with a following space length and the recording mark length in a predetermined timing or in independence; and in relation to the smallest mark recorded by irradiation with mono pulse, changing the rise timing in accordance with the preceding space length and the recording mark length and the fall timing (pulse width) in accordance with the following space length and recording mark length, compensating various optical disks different in recording material without change of the fundamental waveform.

Abstract: An aspect of the present invention relates to an optical information recording medium comprising a recording layer, wherein the recording layer comprises a cationic dye and a polynuclear azo metal complex dye comprising an azo dye and a metal ion, and a method of recording information comprising recording information on the recording layer comprised in the optical recording medium, and conducting the recording by irradiation of a laser beam having a wavelength of equal to or shorter than 440 nm onto the optical information recording medium. Another aspect of the present invention relates to a photo sensitizer.

Abstract: According to one embodiment, an optical recording medium is provided in which interlayer crosstalk is low and in which stable and high-quality recording characteristics can be obtained. To this end, an optical recording medium comprises a first recording part which includes a first recording layer and a first light reflecting layer and which is disposed on a side closer to a light receiving surface, and a second recording part which includes a second recording layer and a second light reflecting layer and which is disposed on a side farther from the light receiving surface, the first recording part and the second recording part being stacked, wherein the thickness of the second light reflecting layer is larger than the thickness of the first light reflecting layer.

Abstract: According to one embodiment, an optical recording medium is provided in which interlayer crosstalk is low and in which stable and high-quality recording characteristics can be obtained. To this end, an optical recording medium comprises a first recording part which includes a first recording layer and a first light reflecting layer and which is disposed on a side closer to a light receiving surface, and a second recording part which includes a second recording layer and a second light reflecting layer and which is disposed on a side farther from the light receiving surface, the first recording part and the second recording part being stacked, wherein the thickness of the second light reflecting layer is larger than the thickness of the first light reflecting layer.

Abstract: There is provided an optical recording method for directing a recording pulse train to an optical disc medium to form marks thereon and for recording information as information about the edge positions of said marks and the spaces between marks, the recording pulse train having been created by modulating laser light into plural power levels. The method includes: coding to-be-recorded data into coded data consisting of the combination of marks and spaces; classifying said marks within said coded data on the basis of the mark length and the preceding or succeeding space lengths of the marks; shifting the position of the second pulse edge counted from the end portion of the recording pulse train for forming said marks, depending on the result of said classification, to adjust said recording pulse train; and directing said recording pulse train to the optical disc medium to form said marks thereon.

Abstract: According to one embodiment, an optical recording medium is provided in which interlayer crosstalk is low and in which stable and high-quality recording characteristics can be obtained. To this end, an optical recording medium comprises a first recording part which includes a first recording layer and a first light reflecting layer and which is disposed on a side closer to a light receiving surface, and a second recording part which includes a second recording layer and a second light reflecting layer and which is disposed on a side farther from the light receiving surface, the first recording part and the second recording part being stacked, wherein the thickness of the second light reflecting layer is larger than the thickness of the first light reflecting layer.

Abstract: According to one embodiment, an optical recording medium is provided in which interlayer crosstalk is low and in which stable and high-quality recording characteristics can be obtained. To this end, an optical recording medium comprises a first recording part which includes a first recording layer and a first light reflecting layer and which is disposed on a side closer to a light receiving surface, and a second recording part which includes a second recording layer and a second light reflecting layer and which is disposed on a side farther from the light receiving surface, the first recording part and the second recording part being stacked, wherein the thickness of the second light reflecting layer is larger than the thickness of the first light reflecting layer.

Abstract: According to one embodiment, an optical recording medium is provided in which interlayer crosstalk is low and in which stable and high-quality recording characteristics can be obtained. To this end, an optical recording medium comprises a first recording part which includes a first recording layer and a first light reflecting layer and which is disposed on a side closer to a light receiving surface, and a second recording part which includes a second recording layer and a second light reflecting layer and which is disposed on a side farther from the light receiving surface, the first recording part and the second recording part being stacked, wherein the thickness of the second light reflecting layer is larger than the thickness of the first light reflecting layer.

Abstract: According to one embodiment, an optical recording medium is provided in which interlayer crosstalk is low and in which stable and high-quality recording characteristics can be obtained. To this end, an optical recording medium comprises a first recording part which includes a first recording layer and a first light reflecting layer and which is disposed on a side closer to a light receiving surface, and a second recording part which includes a second recording layer and a second light reflecting layer and which is disposed on a side farther from the light receiving surface, the first recording part and the second recording part being stacked, wherein the thickness of the second light reflecting layer is larger than the thickness of the first light reflecting layer.

Abstract: The present invention is to realize a proper inner zone layout in an optical disk having at least three layers. A test area is provided in the inner zone (inner circumference side area) in each of recording layers. The test areas of each layer are so disposed as to be prevented from overlapping with each other in the layer direction. Furthermore, the number of management information recording/reproduction areas overlapping with the test area in the layer direction at a position closer to the laser-incident surface than this test area is set equal to or smaller than one in each test area of each recording layer. The management information recording/reproduction areas are each so disposed as to be prevented from overlapping with the test areas in the respective recording layers in the layer direction on the disk substrate side of the test areas.

Abstract: According to one embodiment, an optical recording medium is provided in which interlayer crosstalk is low and in which stable and high-quality recording characteristics can be obtained. To this end, an optical recording medium comprises a first recording part which includes a first recording layer and a first light reflecting layer and which is disposed on a side closer to a light receiving surface, and a second recording part which includes a second recording layer and a second light reflecting layer and which is disposed on a side farther from the light receiving surface, the first recording part and the second recording part being stacked, wherein the thickness of the second light reflecting layer is larger than the thickness of the first light reflecting layer.

Abstract: If a defective cluster in a spare area is managed with a defect entry, the size of a DFL will increase as the size of the spare area increases with an increase in the number of recording layers stacked in a disc. An information recording medium according to the present invention has pointer information indicating the location of the next available cluster in each spare area, and restricts the direction in which the spare area is used. Also, a defect entry indicating a defective cluster in the spare area is registered with the DFL. Thus, even if the size of the spare area 15 increases, the size of the DFL 21 can be kept relatively small. Furthermore, even after physical reformatting is done, a defective cluster, if any, in the spare area 15 can still be recognized as a defect and the control operation can be performed so that a replacement cluster is not re-allocated to that defective cluster (i.e., the defective cluster is not used).

Abstract: An optically-readable disk includes a device that disrupts readability of the disk when the disk is spun at an angular velocity substantially greater than required to play the disk in its intended playing device, or when a defined integral of velocity and time is exceeded. The device may include a fluid container that disperses a data-disruptive fluid. The device may include a membrane or layer that is disrupted when the disk is rotated above a defined angular velocity, or when a defined integral of velocity and time is exceeded. The device may include an electro-optical material that is activated by an electrical signal from a controller in response to an input from a sensor responsive to motion of the disk.

Abstract: Minimized is the influence which is exerted by recording calibration (test recording) such as power calibration, strategy calibration or the like, performed in an area for recording calibration (recording calibration area or test area) provided in each of a plurality of recording layers, on recording calibration performed in the other recording layers. On a recording medium, data is recorded on at least one of a plurality of recording layers by laser light incident on a surface of the recording medium. The plurality of recording layers include a first recording layer, and second through N-th recording layers (N is an integer of 3 or greater) which are sequentially located in a direction from the first recording layer toward the surface on which the laser is incident. The plurality of recording layers each have a first calibration area and a second calibration area located outer to the first calibration area.

Abstract: According to one embodiment, an information storage medium in which layer 0 and layer 1 are arranged from a read surface, a system lead-in area, data lead-in area, data area, and middle area are arranged from an inner circumference of the layer 0, and a system lead-out area, data lead-out area, data area, and middle area are arranged from an inner circumference of the layer 1. A guard track zone is arranged on a side of the data area in the data lead-out area, and a reference code zone, R physical format information zone, recording management zone, and drive test zone are arranged in the data lead-in area of the layer 0 and padding of the guard track zone of the data lead-out area is performed after padding of the drive test zone of data lead-in area and recording of the recording management zone.

Abstract: According to one embodiment, an information storage medium in which layer 0 and layer 1 are arranged from a read surface, a system lead-in area, data lead-in area, data area, and middle area are arranged from an inner circumference of the layer 0, and a system lead-out area, data lead-out area, data area, and middle area are arranged from an inner circumference of the layer 1. A guard track zone is arranged on a side of the data area in the data lead-out area, and a reference code zone, R physical format information zone, recording management zone, and drive test zone are arranged in the data lead-in area of the layer 0 and padding of the guard track zone of the data lead-out area is performed after padding of the drive test zone of data lead-in area and recording of the recording management zone.

Abstract: A signal evaluation method according to the present invention is a method for evaluating a read signal, retrieved from an information recording medium, based on a binarized signal generated from the read signal by a PRML method.

Abstract: A format of a recordable optical recording medium is described. The recordable optical recording medium is designed in such a way that it has the appearance of a read-only optical recording medium for most players and recorders. Also described are a method for manufacturing the recordable optical recording medium and a method for writing to the optical recording medium. The optical recording medium has a recording area and a guide structure for tracking. The guide structure does only extend over one or a few track spirals or concentric tracks outside the recording area. For writing to this optical recording medium a further light beam falling onto the guide structure or already recorded data is used for generating a tracking error signal for a main light beam.

Abstract: There is provided an optical disc having preformed thereon a spiral wobbled track as a grove and/or land along with data is to be recorded. The track is wobbled for a series of predetermined signal units each composed of an FSK information bit part based on a waveform resulted from FSK modulation of information bit and a singe-frequency part based on a waveform of a single frequency. The FSK modulation uses two different frequencies of which the one is the same as the single frequency and the other is different from the single frequency. These different frequencies are in such a relation that each of them has an even number of wobbles and an odd number of wobbles alternately in a predetermined cycle.

Abstract: In an optical disk including at least a rewritable phase change material and comprising a recording layer having a reflectivity of more than 15%, an address output value as an address pit signal component occupying in a reproduced signal in a non recording state is prescribed to be 0.18 though 0.27 or a numerical aperture of an address pit signal occupying in a reproduced signal in a non recording state is prescribed to be more than 0.3.

Abstract: According to the invention, techniques for recording data onto recording media at relatively high transfer rates for relatively long periods of time. Embodiments according to the present invention include systems and apparatus capable of an improved sustained rate of data recording onto disk type-recording media, for example. Many embodiments can remove the upper limits of both recording capacity and the number of media that can be used. Select embodiments can be used with different kinds of recording media as well. In a specific embodiment, the area on a hard disk is divided into three areas. A first area can be suitable for sequential recording of continuous data. A second area can be suitable for random recording of discontinuous data. A third area can be used for recording logical sector numbers, coupling logical sector numbers, and file information that are used for marking each of the first and second areas, so that continuous data can be recorded on the hard disk at a high data rate.

Abstract: An address format for appropriately controlling the recording linear density and the number of information recording layers is provided in order to increase the recording capacity of an information recording medium such as an optical disc or the like in a range in which a necessary S/N ratio can be guaranteed. An optical disc includes an information recording layer having a concentric or spiral track, and has a format for describing a track address, which is pre-recorded on the track or is to be added to data that is to be recorded on the information recording layer. The format includes layer information regarding the information recording layer and address information regarding the track address.

Abstract: A big pattern for a run-in area which allows data reproduction to be performed stably even when the recording density of an optical disc is increased is provided. An optical disc according to the present invention includes tracks, each of which divided into a plurality of recording blocks. Each of the plurality of blocks includes a run-in area and a data area. In the run-in area, a prescribed run-in bit pattern is recordable; and in the data area, bit patterns having a plurality of bit lengths obtained by modulating data as a recording target in accordance with a prescribed modulation rule are recordable. In this optical disc, at least one of spatial frequencies corresponding to the bit patterns having the plurality of bit lengths is higher than a cutoff frequency. The run-in bit pattern recordable in the run-in area includes the bit patterns having the plurality of bit lengths, from which the bit pattern corresponding to the frequency higher than the OTF cutoff frequency has been excluded.

Abstract: An information recording medium 1 at least comprises a substrate 13 having a microscopic pattern 20, which is constituted by a shape of continuous substance of approximately parallel grooves formed with a groove section G and a land section L alternately, a recording layer 12 formed on the microscopic pattern 20 and a light transmission layer 11 formed on the recording layer. The microscopic pattern 20 is formed so as to satisfy a relation of P<?<NA and a thickness of the light transmission layer 11 is within a range of 0.07 to 0.12 mm, wherein P is a pitch of the groove section G or the land section L, ? is a wavelength of reproducing light beam and NA is a numerical aperture of an objective lens.

Abstract: If a defective cluster in a spare area is managed with a defect entry, the size of a DFL will increase as the size of the spare area increases with an increase in the number of recording layers stacked in a disc. An information recording medium according to the present invention has pointer information indicating the location of the next available cluster in each spare area, and restricts the direction in which the spare area is used. Also, a defect entry indicating a defective cluster in the spare area is registered with the DFL. Thus, even if the size of the spare area 15 increases, the size of the DFL 21 can be kept relatively small. Furthermore, even after physical reformatting is done, a defective cluster, if any, in the spare area 15 can still be recognized as a defect and the control operation can be performed so that a replacement cluster is not re-allocated to that defective cluster (i.e., the defective cluster is not used).

Abstract: A server device without a means for accessing an IC memory included in a data storage medium can check whether or not a data storage medium includes an IC memory. A portable optical disc medium (100) includes an IC memory (106) accessible through proximity wireless communication and a computer-readable recording part (101). The recording part (101) includes a user-data area (104) in which content data is recorded and a disc management information area (103) in which information for management of recording and reproducing the content data. In the disc management information area (103), medium identification information identifying the optical disc medium (100) and presence indication information indicating that the optical disc medium (100) includes presence of the IC memory (106) in a manner such that the presence indication information does not allow changing.

Abstract: Compatibility information embedded in an optical medium modifies actions allowed by predetermined non-compatible optical disc drives on the optical medium, such as optical disc drives that may suffer damage if certain actions are performed on the optical medium. For instance, a compatibility engine of the optical disc drive applies compatibility information read from an optical medium to determine restrictions to impose on the use of the optical medium, such as restricting the optical disc drive from writing to the optical medium, reading from the optical medium or performing any operations until an update to the optical disc drive firmware is performed either automatically or by display of a compatibility user interface at an information handling system associated with the optical disc drive. In one embodiment, the compatibility information identifies incompatible optical disc drives and firmware versions by unique identifiers.

Abstract: A compatible optical recording medium is described, which is designed in such a way that it has the appearance of a read-only optical recording medium for most players and recorders. Further described is a method for manufacturing the recordable optical recording medium. The optical recording medium has an essentially flat recording layer with a first reflectivity at a wavelength specified for a reading recording light beam, which has an alloyed guide track formed of the material of the essentially flat recording layer with a second reflectivity different from the first reflectivity at the specified wavelength.

Abstract: A computer readable medium, apparatus, and method for efficiently managing a space bitmap. A computer readable medium includes: a user data area on which user data is recorded; and a temporary disc management area on which a space bitmap indicating a recording status of recording and reproducing unit blocks of the user data area is recorded. The space bitmap includes header information for distinguishing an additional space bitmap from the space bitmap. The additional space bitmap is assigned when a space provided for the space bitmap is insufficient to represent the recording status of the recording and reproducing unit blocks of the user data area.

Abstract: An optical article is provided. The optical article includes a first layer. The first layer includes an active holographic layer configured to store holographic data. The first layer has a first surface and a second surface. A second layer includes a low birefringence material. The second layer also has a first surface and a second surface. Guide grooves are present in any one of the first layer or the second layer. In certain embodiments, the article may further include a reflective layer, an anti-reflective layer, a barrier layer, and a combination thereof.

Abstract: An object of the invention is to provide an optical recording medium and an optical information device that enable to improve the quality of a servo signal and a reproduction signal.

Abstract: A protective cover for covering the recording surface of a disk-like recording medium so that the recording surface does not come into contact with other objects. The disk-like recording medium can be easily attached to and detached from the protective cover. The protective cover (2), made of resin, covers the recording surface of the recording medium (1) to protect the recording surface. The diameter of the protective cover (2) is set smaller than that of the recording medium (1), an outer peripheral part (11) of the protective cover (2) comes into contact with a margin portion on the outer peripheral side of a recording area of the recording surface of the recording medium (1), and, in the area between the outer peripheral part (11) and an inner peripheral contact part (12) coming into contact with margin portion, a cover body (10) of the protective cover is separated from the recording surface of the recording medium (1).

Abstract: An environmental load information of an information recording medium is recorded on the information recording medium so as to recycle or dispose properly an information recording medium, which is not necessary any more. The information recording medium comprises a main information area (102) for recording or reproducing information and a recording area (101) for environmental load information, which is recorded with an environmental load information of the information recording medium.

Abstract: An optical disc is disclosed having a set of primary tracks and a set of alternate tracks. At least some of the primary and alternate tracks are associated. When a CD-DA reader accesses the optical disc, it locates only the primary tracks. By contrast, when a data reader such as a CD-Rom drive accesses the disc, modifications to the Table of Contents (TOC) cause the data reader not to access a given primary track but instead to be directed to its associated alternate track. This alternate track may contain audio (CD-DA) data which may or may not correspond with the CD-DA data in the associated primary track. The alternate tracks may be copy protected, and/or may include compressed (not CD-DA) data which is the subject of digital rights management.

Abstract: There is provided a method of manufacturing an optical recording medium capable of reducing a manufacturing cost of an optical recording medium. When manufacturing an optical recording medium 10 including a recording layer 2 formed on a substrate 1, and a light transmitting layer 3 formed on the recording layer 2, the method of manufacturing the optical recording medium includes a step of forming the recording layer 2 containing In and/or Sn, Pd, and oxygen through a use of sputtering method by using an In2O3 target and/or a SnO2 target, and a Pd target while allowing an oxygen gas and a nitrogen gas to flow.

Abstract: The present invention relates to a high-density optical data storage structure. The structure comprising a substrate provided with physical marks, said physical marks being covered by at least one active layer, the physical state of the active layer being modified when irradiated by a laser beam, the substrate consisting of adjacent tracks that are alternately recessed and protruding, the physical marks consisting of pits in the land tracks and of bumps in the groove tracks. The invention is applicable, notably, to the production of high storage capacity optical disks and more particularly to the production of prerecorded optical disks.

Abstract: An optical recording medium, an apparatus and method of manufacturing an optical recording medium, and an apparatus and method of recording/reproducing data of an optical recording medium, allocated with a wobble address suitable for a capacity of a high density recording disc, the optical recording medium including a first area and a second area on which data is recorded/reproduced by a recording/reproducing apparatus, the optical recording medium including: a recording unit block on which the data is recorded or reproduced, and a wobble address corresponding to the recording unit block and indicating a location of the recording unit block in the optical recording medium, the wobble address including a plurality of address units (ADIPs), wherein last two bits in the ADIPs in the first area are one of: 00, 10, and 01, and last two bits in at least one ADIP in the second area are 11.

Abstract: Where a hybrid disc has different types of media, the light spot moves among recording layers of the different media, after loading the disc into an optical disc apparatus, there is a problem that information on a media type of each recording layer should be recorded in DI etc. of the optical disc. Detailed information on the hybrid disc is stored in DI, by changing a disc layer type identifier or a disc structure in DI such as BCA or PIC on the optical disc.

Abstract: The optical storage medium comprises a substrate layer, a data layer having a pit/land data structure with data arranged in tracks on the substrate layer, and a nonlinear layer with a super-resolution structure disposed on the data layer, wherein a land having a size below the diffraction limit is inverted to a pit and enclosed by auxiliary lands, and a pit having a size below the diffraction limit is inverted to a land and enclosed by auxiliary pits. The optical storage medium is in particular a read-only optical disc comprising a phase-change material, for example AgInSbTe, for providing the super-resolution effect.

Abstract: An optical disc medium comprises a track groove, along which main information is recorded. The track groove is divided into a plurality of blocks. The plurality of blocks each include a plurality of frames. The plurality of frames each include one shape of wobbles indicating sub information, among a plurality of prescribed shapes of wobbles. The plurality of blocks each have address information. The address information is represented by a string of at least one piece of sub information represented by the shape of wobbles of at least one of the plurality of frames.

Abstract: According to the present invention, multiple space bitmaps (SBMs #0 and #1 30) are provided for the user data area of each recording layer. A disc management structure update unit including one of those space bitmaps and a disc definition structure (TDDS 32) and having a size of one block is written on a management information area (TDMA 17). As a result, data including the disc definition structure (TDDS 32) can always be arranged in the first block at the top of the management information area (TDMA 17).