Abstract: A multi-layered information recording medium used in an information recording/reproducing apparatus applicable to both a single-layer information recording medium and an arbitrary multi-layered information recording medium is provided. The multi-layered information recording medium has a plurality of recording layers, and each of the recording layers has a guiding groove formed at a track pitch defined as a quadratic function of disk thickness (i.e., the distance from the light incident surface) of the associated recording layer. The guiding grooves of the recording layers are formed such that the track pitch of a reference recording layer having a disk thickness closest to that of the single-layer information recording medium is the smallest amongst the multiple recording layers.

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: Optical disks are formed using mother stampers having a spiral groove and/or a spiral pattern of pits corresponding to the pattern from an original laser cut. The mother stamper is the mirror image of the corresponding father stamper. Injection molding of polycarbonate material or other suitable material using the mother stamper forms an optical disk having lands and bumps corresponding to the original laser cut. A phase-change material having constructive change in phase and thickness is deposited over the polycarbonate material to create the disk. Data is written to and read from the lands, and tracking is performed on the wobbled lands.

Abstract: An optical pickup for irradiating an information recording medium, such as a DVD, with a laser beam when an information signal is recorded or reproduced, and information equipment provided with the optical pickup.

Abstract: In order to distinguish a duplicated record carrier from an original record carrier, a pattern is included in a ROM type record carrier. The pattern is oriented perpendicular to the reading direction of the record carrier. During illegal duplication the spatial relationship is disturb which can be easily detected. The patterns can be read out simultaneously by the same single read-out spot by including both patterns within the diameter of the optical spot, thus guaranteeing that the read-out patterns are actually still spatially close together.

Abstract: An information recording medium includes a plurality of layers for recording or reproduction of information by irradiation, wherein each of the layers includes an emboss portion and wobble portion including wobbles of a first frequency and a second frequency that is different from the first frequency. The first frequency is constant in each of the plurality of layers, and a different signal is obtained from the wobbles of the first and second frequencies in each of the plurality of layers.

Abstract: An optical disk read only memory having an information recording surface with a concave-convex pattern formed on the basis of a first signal and a reflective film covering the surface. The disc medium includes: an additional information recording section formed on a recording track of a first data string; and a second data string including a mark of removing or reducing the reflective film. The modulation methods of the first and the second data strings are identical, and Lh(n)>Lp1(n) and Wh(n)>(Wp1(n)+Wp2(n))/2 are satisfied, where a reference clock cycle is T, a data length is nT, a length and a width of the mark are Lh(n) and Wh(n), a length and a width of a base of the pit are Lp1(n), and Wp1(n), a length and a width of a top face of the pit is Lp2(n) exceeding Lp1(n), and Wp2(n) exceeding Wp1(n).

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: Plural grooves or lands formed in an information recording carrier include at least a wobbling region and data is recorded wobblingly in this wobbling region by phase shift modulation while recorded digitally with a single or multiple waves as a channel bit.

Abstract: In a single-sided incident type optical recording medium having a plurality of dye containing recording layers, sufficient reflectance and excellent recording characteristics necessary to record or read information in or from a dye containing recording layer positioning farther from a side from which a light beam comes in can be obtained. The optical recording medium has a first substrate (21) having a guide groove, a first dye containing recording layer (22), a semitransparent reflective layer (23), an intermediate layer (24), a second dye containing recording layer (25), a reflective layer (26) and a second substrate (27) having a guide groove. Information is recorded or read in or from the first dye containing recording layer (22) and the second dye containing recording layer (25) by irradiating the light beam from the first substrate's side. The depth of the guide groove on the second substrate is within a range from 1/100×? to ?×? where ? represents the recording/reading wavelength.

Abstract: A code disk for a high-resolution encoder that can detect an absolute position and a method for manufacturing a mold to produce the code disk are provided. The code disk is formed by using transparent substrate. The code disk includes a plurality of tracks provided on the transparent substrate and an area provided between the plurality of tracks. Each surface of the plurality of tracks has a different pattern. A level of the area is different from that of the each surface of the plurality of tracks. The method for manufacturing the mold includes steps of processing a plurality of tracks with a flat surface on material; processing an area with a level different from that of each surface, between the plurality of tracks; forming different patterns on the each surface; plating the first material; and peeling plating from the first material to obtain a mold.

Abstract: An optical information recording medium includes a substrate, n information recording layers provided on the substrate, and spacer layers, each of which is provided so as to be interposed between the information recording layers, wherein each of (n?1) or more of the information recording layers has a layer number information part that is formed in correspondence with one or more recording marks X and contains layer number information, where n represents an integer of not less than 2, and the layer number information is information used for determining which a given information recording layer is among the n information recording layers. Each recording mark X has a length in a circumferential direction longer than a length of a recording mark Y used for recording another information in the information recording layers.

Abstract: An information recording medium is at least composed of a substrate having a microscopic pattern constituted by a continuous substrate of grooves formed with a groove portion and a land portion alternately, a recording layer formed on the microscopic pattern for recording information, and a light transmitting layer formed on the recording layer. The microscopic pattern is formed with satisfying a relation of P??/NA, wherein P is a pitch of the land portion or the groove portion, ? is a wavelength of reproducing light for reproducing the recording layer, and NA is a numerical aperture of an objective lens. The land portion is formed with wobbling so as to be parallel with each other for both sidewalls of the land portion. An auxiliary information based on data used supplementally when recording the information and a reference clock based on a clock used for controlling a recording speed when recording the information is recorded alternately.

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: There is provided a new medium structure to record a bar code for copyright protection or the like in an optical information recording medium capable of recording and reproducing information by a laser with respect to a dye. When a laser beam 30 is irradiated and an optical disc 10 is rotation in the direction of an arrow F, the dye of a recording layer is decomposed, a mark piece MA of a bar code 20 is formed, and a substrate is deformed by heat generated by the dye decomposition. Next, the position of the laser beam 30 is shifted to a position where a part overlaps with the mark piece MA, and when the optical disc is similarly rotated in the direction of the arrow F, a mark piece MB is formed to overlap with the mark piece MA. The above processing is repeated, so that the length of a bar is sequentially lengthened, and the bar code with a length along the standard is formed.

Abstract: In an information recording medium comprising at least a substrate, a recording layer, and a resin layer, the substrate is formed with at least a pit corresponding to a read only area 31 and a groove corresponding to a recording/reproducing area 32 without overlapping with each other. A reflectivity of the recording layer is specified to be more than 10%. The recording layer and the resin layer are continuously adhered over both the read only and recording/reproducing areas 31 and 32. The information recording medium is characterized in that both push-pull signal outputs T1 and T2, which are reproduced from the read only area 31 and the recording/reproducing area 32 respectively, are more than 0.1 and satisfy an inequality 1.5?T1/T2?0.5.

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: 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: 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 one embodiment, a write-once information recording medium includes a transparent resin substrate having concentric or spiral grooves and lands, and a recording film formed on the grooves and lands of the transparent resin substrate, wherein the recording film includes an organic dye layer containing a metal complex monomer and a metal complex polymer, a recording mark is formed in the organic dye layer by emission of a short-wavelength laser beam, and a light reflectance of the recording mark formed by emission of the short-wavelength laser beam is higher than that before emission of the short-wavelength laser beam, and the grooves wobble within a predetermined amplitude range.

Abstract: A system controlling recording on an optical disc is provided. A first counter performs a bit count according to provided channel bit clock signals. A second counter performs a sector count responsive to the bit count obtained by the first counter. The Land/Groove switch predicts machine uses the result of bit count and sector count to predict the land/groove switch point. The processor uses the physical ID (PID) to determine the track type of a sector at which a recording operation initiates. The power controller determines a recording power for the recording operation according to the Land/Groove switch predict machine.

Abstract: A disclosed optical information recording medium includes a guide track layer having grooves and ridges; and recording layers composed of an optical recording material and disposed above and below the guide track layer. The guide track layer is used to determine track positions on the recording layers.

Abstract: An optical disk medium in which high density recording/reproducing is possible, an information recording method and an information reproducing method using it are provided. A pit composed of a phase change material and a recording film different from it are provided on an optical disk. The phase change pit has a pattern of a single frequency. A mark having a size on the same level as the phase change pit can be formed by melting a single phase change pit while recording and controlling the optical absorbance and the temperature of the recording film at the region. A single phase change pit is molten while reproducing. Since the optical characteristics of the molten region are different from the optical characteristics of other regions, only data at the molten region can be reproduced by a super-resolution effect.

Abstract: An optical recording medium has a user data area and a lead-out area, wherein the user data area and the lead-out area each has grooves and lands formed thereon. Wobbles are formed on at least one lateral surface of grooves of the user data area and the lead-out area, and configured such that wobble characteristics are made different between the user data area and the lead-out area. Different types of wobbles are formed on the grooves of either the user data area or the lead-out area, thereby preventing an optical pickup that performs recording/reproduction from deviating from the user data area. Also, in a multi-layer optical recording medium, a whole area of a recording layer is configured to have a same condition, thereby preventing deterioration in reproduction and/or recording due to a difference in light power transmittance of another recording layer.

Abstract: An information recording carrier according to one embodiment has minute pattern including plural grooves or lands formed to be substantially in parallel and adjacent each other and comprises a supporting body having the minute pattern, a recording layer formed on the minute pattern formed on the supporting layer and a light transmission layer formed on the recording layer. The minute pattern is formed under a relation of P<?/NA, where a pitch of each groove or land is P, a wavelength of a laser beam is ? and a numerical aperture of an objective lens is NA. The plural grooves or lands have at least a wobbling region and data is recorded wobblingly in the wobbling region by frequency shift modulation. A phase relation between a high frequency portion and a low frequency portion composing the frequency shift modulation is ±(?/20.5) to ±(?/0.75). The data is also recorded wobblingly in the wobbling region by bi-phase modulation.

Abstract: A write-once information recording medium comprises a transparent resin substrate having a concentrically or spirally shaped groove and a land formed thereon, and a recording firm formed on the groove and the land of the transparent resin substrate, a recording mark being formed on the medium by emission of a short wavelength laser light, the recording medium having an L to H feature in which a light reflectivity of the recording mark portion formed by the emission of the short wavelength laser light is higher than a light reflectivity obtained before the emission of the short wavelength laser light.

Abstract: An optical-disc writer writes extrinsic data to an optical disc. Extrinsic data can be written as (i) embedded marks (e.g., pits and lands) located outside the conventional readable area of a disc and/or (ii) alternative marks, such as surface marks located on a surface of the disc. In an optical-disc player having a disc-reading subsystem and a read controller, the disc-reading subsystem reads and relays the extrinsic data to the read controller, which controls the operations of the player based on the extrinsic data. For example, the writer prints extrinsic data, e.g., a barcode, on the surface of a software installation disc. The disc is inserted in the player and installation is commenced. The read controller instructs the disc-reading subsystem to read the extrinsic information. If the read controller determines that the extrinsic data was successfully read, then installation proceeds; otherwise, installation is halted.

Abstract: To provide an optical disk and an optical disk reproducing device capable of preventing sub information from being illegally copied and altered. An optical disk includes an optical disk substrate preliminarily provided with concave/convex recording marks in order to record the main information; and a reflection film which covers the optical disk substrate and of which the reflection coefficient is changed by irradiating laser light at or above a certain intensity. The reflection film is preliminarily provided with additional marks for recording the sub information by changing the reflection coefficient of the reflection film on a region where the concave/convex recording marks are formed and the sub information is recorded for every predetermined recording unit for recording the main information. The laser light at or above the certain intensity is irradiated onto the region where the sub information is recorded to reproduce the main information and delete the sub information.

Abstract: The optical storage medium comprises a substrate layer, a data layer, and a nonlinear layer with a super-resolution structure disposed on the data layer, wherein pits and lands having a size above a diffraction limit of a pickup for reading of the data establish a first and a second level of the data layer, and pits and lands having a size below the diffraction limit of the pickup are arranged on a further level of the data layer. In a preferred embodiment, pits having a size below the diffraction limit are arranged on a third level and lands having a size below the diffraction limit are arranged on a fourth level of the data layer. 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 data recording medium, in which irradiation of a light beam is used for recording and/or reproducing data includes (i) a substrate having an a rise and/or a recess which are a light-incident surface, (ii) a reflective layer, provided on the light-incident surface of the substrate, for reflecting the light beam, (iii) a light absorption layer for converting, to heat, a light of the light beam to heat on the surface of the reflective layer, (iv) a reproducing layer, provided on the surface of the heat-light converting layer, having a transmittance that changes in accordance with a light intensity distribution of the light beam. The optical data recording medium is excellent in super-resolution property, and enables reproduction of a shorter mark length.

Abstract: An optical information recording medium comprises at least a substrate on which a groove is formed in a recording area, a recording layer comprising an organic dye, and a reflective layer. The recording area has a preformat area and a data area, and the groove in the preformat area is narrower or shallower than that in the data area.

Abstract: An optical recording medium includes a main-information area in which a metal reflection film is formed on a substrate where a row of pits is formed as main data, and a sub-information area in which is recorded medium identification information, which is used to identify the optical recording medium individually, by removing the metal reflection film partially and forming a plurality of reflection-film removed areas. Information is reproduced by irradiating the metal reflection film with a beam of light. In the sub-information area, a row of pits or a guide groove is formed on the substrate, and a track pitch of the row of pits or the guide groove is at least 0.24 ?m wide and at most 0.45 ?m wide.

Abstract: An information-recording medium having a substrate and a recording part formed on the substrate allowing three-dimensional formation of recording pits, the recording part, comprising multiple recording layers, in which the recording pits are formed with a converged recording light at a wavelength of ?2 and reproduced with a converged reproducing light with a wavelength ?1 shorter than the wavelength ?2, and intermediate layers alternately laminated between the recording layers, wherein the reflectance at the recording light wavelength of ?2 in the unrecorded region is smaller than the reflectance at the reproducing light wavelength of ?1 in the unrecorded regions of the recording layers.

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: Multilayer optical disk is recordable or partly recordable. Parallel reading of information data from the group of layers by the same focused laser beam is possible. Only one layer of said group has the guide grooves for tracking. Alignment of the information data disposition on the layers of the group is provided. The signals reflected from the different layers of the group have different tilts and are directed onto the different photodetectors. Optical disk management for preventing its illegal use is proposed.

Abstract: An optical information storage medium includes a plurality of areas and at least one transition area. Each transition area is located between two adjacent areas. The transition area allows data to be smoothly reproduced from the optical information storage medium at a low error generation rate. Also, since the optical information storage medium provides standards for the transition area, it is compatible with existing optical information storage media.

Abstract: An optical information recording medium includes a read-only information recording portion, and a BCA (Burst Cutting Area) portion formed by laser marking. A reflective film on an information recording surface of the read-only information recording portion and a reflective film on the BCA portion are formed of the same material. The reflective film includes Ag as a main component, and at least one of Nd and Gd, and at least one of Sn and In as components; the reflective film including at least one of Nd and Gd of 0.1 atom % or more and 3.0 atom % or less in total and at least one of Sn and In of 3 atom % or more and 12 atom % or less in total. Recorded information is reproduced from the information recording surface of the read-only information recording portion and a BCA signal is reproduced from the BCA portion, using blue-violet laser reproducing light.

Abstract: Conventionally, as in the case of switching between a DVD-R and a DVD-RAM, when the method of record mark arrangement in a track is changed, the physical format of the disk is also changed. This makes it difficult to ensure compatibility between pieces of data recorded by a plurality of different methods of record mark arrangement. According to the present invention, sector address data and block address data are recorded in each sector by using wobbling or deformation of a recording groove. Then, depending on which address is used, sector data structure is modified, thereby making it possible to select an address data detection and a data structure on a disk in a single physical format depending on the purpose.

Abstract: A high-density read-only optical disc, and an optical disc apparatus and method using the same. The apparatus and method record data on a lead-in area of a high-density read-only optical disc such as a BD-ROM (Blu-ray disc ROM (Read Only Memory)) in the form of pre-pit strings associated with an HFM (High-Frequency Modulated) groove applied to a BD-RW (Blu-ray Disc Rewritable). Moreover, the apparatus and method continuously apply the same tracking servo operation to an entire area of the same high-density read-only optical disc or rewritable optical disc. Therefore, the apparatus and method can simplify an algorithm for controlling a plurality of tracking servo operations, and avoid an increased size of the optical disc apparatus.

Abstract: In an information recording medium comprising at least a substrate, a recording layer, and a resin layer, the substrate is formed with at least a pit corresponding to a read only area 31 and a groove corresponding to a recording/reproducing area 32 without overlapping with each other. A reflectivity of the recording layer is specified to be more than 10%. The recording layer and the resin layer are continuously adhered over both the read only and recording/reproducing areas 31 and 32. The information recording medium is characterized in that both push-pull signal outputs T1 and T2, which are reproduced from the read only area 31 and the recording/reproducing area 32 respectively, are more than 0.1 and satisfy an inequality 1.5?T1/T2?0.5.

Abstract: A record carrier including a data area for storing data in the form of marks, in which the data is encoded by means of a channel code, wherein a parameter of the channel code is controlled so as to introduce a predetermined run length distribution in the marks on the record carrier, thereby introducing first information relating to a watermark, and a non-data area comprising second information relating to a watermark, the first and the second information forming the watermark. This watermark, extending over the data-area and the inner-ring area and/or the outer-ring area, can be used for checking the authenticity of the record carrier and/or the recordings made on this record carrier.

Abstract: A guide groove is formed without wobbles. The guide groove is periodically modulated with its width. Encrypted data are recorded with marks formed on the record film along the guide groove. Information recorded by periodically modulating the guide groove with its width can be accurately detected by a band pass filter. Thus, rotation control information and address information can be stably reproduced. In addition, since the guide groove is formed without wobbles, a drive device having a pirated disc determination mechanism can reproduce encrypted content as with a ROM disc.

Abstract: An apparatus for reading subdivided information from an optical disk, which comprises a track groove and on which information is recorded along the track groove is disclosed. The apparatus includes an optical head, which irradiates the optical disk with light and generates an electric signal responsive to part of the light that has been reflected from the optical disk, read signal processing means for generating a wobble signal which has an amplitude changing with the wobble pattern from the electric signal, rise value acquiring means for sampling and holding an absolute gradient value of the wobble signal when the signal rises, fall value acquiring means for sampling and holding an absolute gradient value of the wobble signal when the signal falls, and subdivided information detecting means for determining the subdivided information by majority by comparing the values held by the rise and fall value acquiring means with each other.

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: In an information recording medium comprising at least a substrate, a recording layer, and a resin layer, the substrate is formed with at least a pit corresponding to a read only area 31 and a groove corresponding to a recording/reproducing area 32 without overlapping with each other. A reflectivity of the recording layer is specified to be more than 10%. The recording layer and the resin layer are continuously adhered over both the read only and recording/reproducing areas 31 and 32. The information recording medium is characterized in that both push-pull signal outputs T1 and T2, which are reproduced from the read only area 31 and the recording/reproducing area 32 respectively, are more than 0.1 and satisfy an inequality 1.5?T1/T2?0.5.

Abstract: A recording medium includes a substrate having a microscopic pattern, which includes a shape of continuous substance of approximately parallel grooves formed with a convex shaped section and a concave shaped section alternating on a surface of the substrate. A recording layer is formed on the microscopic pattern and a light transmitting layer has a thickness of 0.05 mm to 0.12 mm formed on the recording layer. The microscopic pattern satisfies a relation of P??/NA, wherein P is a pitch of the convex shaped section, ? is a wavelength of a reproducing light beam and NA is a numerical aperture of an objective lens. The microscopic pattern also includes modulated address information formed on both side walls of the convex shaped section viewed from the light transmitting layer as a wobble, both the side walls being parallel to each other, and furthermore wherein the address information is modulated by the phase-shift keying modulation system.

Abstract: In an information recording medium comprising at least a substrate, a recording layer, and a resin layer, the substrate is formed with at least a pit corresponding to a read only area 31 and a groove corresponding to a recording/reproducing area 32 without overlapping with each other. A reflectivity of the recording layer is specified to be more than 10%. The recording layer and the resin layer are continuously adhered over both the read only and recording/reproducing areas 31 and 32. The information recording medium is characterized in that both push-pull signal outputs T1 and T2, which are reproduced from the read only area 31 and the recording/reproducing area 32 respectively, are more than 0.1 and satisfy an inequality 1.5?T1/T2?0.5.

Abstract: The invention provides an optical disc and a registering method for labeling on a label side of the optical disc. More particularly, the label side has a plurality of turns of wobbled grooves connected in series to form a spiral track. The turns of the wobbled grooves are then to provide a registering reference.

Abstract: An optical disk structure and optical disk recorder which enables data to be rewritten onto the recording layer of the optical disk. A clock reference structure is permanently formed along servo tracks of the optical disk. An optical transducer is coupled to the clock reference structure and generates a clock reference signal simultaneously with writing new data onto the recording layer of the optical disk. The data is written as data marks along the servo tracks. Each of the data marks includes edges. The edges of the data marks are recorded in synchronization with a write clock. The write clock is phase-locked with the clock reference signal. Therefore, the edges of the data marks are aligned with the clock reference structure with sub-bit accuracy. Standard DVD-ROM disk readers are not able to detect the high spatial frequency of the clock reference structure.

Abstract: An optical recording medium has a user data area and a lead-out area, wherein the user data area and the lead-out area each has grooves and lands formed thereon. Wobbles are formed on at least one lateral surface of grooves of the user data area and the lead-out area, and configured such that wobble characteristics are made different between the user data area and the lead-out area. Different types of wobbles are formed on the grooves of either the user data area or the lead-out area, thereby preventing an optical pickup that performs recording/reproduction from deviating from the user data area. Also, in a multi-layer optical recording medium, a whole area of a recording layer is configured to have a same condition, thereby preventing deterioration in reproduction and/or recording due to a difference in light power transmittance of another recording layer.