Abstract: An optical disc includes an information recording layer having a record of information as a pit train with a predetermined track pitch and a light-transmissive layer formed on the information recording layer so that the information can be reproduced by a beam of light illuminated through the light-transmissive layer to the information recording layer by an objective lens. The optical disc includes a feature in that a relationship of 0.194(?/NA)2?TP ×Tmin?0.264(?/NA)2 is satisfied, provided that the track pitch is TP, a pit shortest length is Tmin, a wavelength of the light beam is ? and a numerical aperture of the objective lens is NA. The optical disc also includes a feature in that a pit width is 120 nm or smaller in a range of a track pitch of 0.280 to 0.325 ?m.

Abstract: Image information is reproduced in respectively correspondence to monitors of different aspect ratios as in the NTSC system or HDTV system adaptive type. The image information recorded on a video disc is reproduced. An ID signal held in the video disc is detected. The aspect ratio of the image information to be generated is designated. Only when the aspect ratio indicated by the detected ID signal differs from the designated aspect ratio, the reproduced image information is converted into the image information of the designated aspect ratio. A standardized image signal is produced on the basis of the converted image information.

Abstract: So as to prevent from illegally copying and illegally reproducing data with reliability, a ROM disk comprises: a data area where data to be reproduced is recorded; and a PEP area where the information necessary to reproduce the data recorded in the data area is recorded in the form of the zonal pit rows, and a recordable optical disk records a signal which prevents from recording the zonal pit rows into the area which is equivalent to the PEP area of the ROM disk, of the recordable optical disk.

Abstract: Image information is reproduced in respectively correspondence to monitors of different aspect ratios as in the NTSC system or HDTV system adaptive type. The image information recorded on a video disc is reproduced. An ID signal held in the video disc is detected. The aspect ratio of the image information to be generated is designated. Only when the aspect ratio indicated by the detected ID signal differs from the designated aspect ratio, the reproduced image information is converted into the image information of the designated aspect ratio. A standardized image signal is produced on the basis of the converted image information.

Abstract: Image information is reproduced in respectively correspondence to monitors of different aspect ratios as in the NTSC system or HDTV system adaptive type. The image information recorded on a video disc is reproduced. An ID signal held in the video disc is detected. The aspect ratio of the image information to be generated is designated. Only when the aspect ratio indicated by the detected ID signal differs from the designated aspect ratio, the reproduced image information is converted into the image information of the designated aspect ratio. A standardized image signal is produced on the basis of the converted image information.

Abstract: The invention relates to an optical disc of the next generation which is capable of recording data at a high density by using an optical system having a larger numerical aperture and a reproduce beam of light with a shorter wavelength than those used with a conventional DVD. The optical disc includes an information recording layer where information is recorded as an array of pits at a predetermined track pitch, and a light transmitting layer formed on the information recording layer and having a film thickness of 0.13 mm or less. The information recorded therein is reproduced upon irradiation of a beam of light having a wavelength ranging from 400 nm to 415 nm onto the information recording layer through the light transmitting layer from an objective lens having a numerical aperture ranging from 0.75 to 0.86. In this disc, a taper angle of the pits is 55 degrees or higher.

Abstract: A transmitting method of digital data whereby information data can be reproduced at a high precision. In order to retain digital data in sectors comprising a plurality of sync frames and sequentially transmit, the sync frame is comprised of the sync signal and the run length limited code which satisfies the limitations of the minimum run length and the maximum run length, and the sync signal includes the sync pattern constituted by a bit pattern of a run length that is longer than the maximum run length by only 3T and addition bit patterns which are arranged before and after the bit pattern and each of which has a run length that is longer than the minimum run length. The sync signal includes a specific code which indicates a position in the sector and which enables the DC control to be performed.

Abstract: A digital modulation apparatus applies a method for converting data words to runlength-limited code words using plural conversion tables. The data words are converted to code words that significantly suppress the low frequency component of the final nonreturn-to-zero inverted signal.This digital modulation apparatus includes ROM tables for storing plural conversion tables containing the runlength-limited code words corresponding to the data words; end-runlength memories and evaluators for determining whether the runlength-limit constraints are satisfied in the interconnection between two consecutive code words when the data words to be converted are supplied; and a DSV controller for storing each of the code words that can be selected from two conversion tables to buffer memories when the runlength-limit constraints are satisfied, and selecting the code words wit the greatest effect suppressing the low frequency component in the obtained signal when the code words are NRZI converted.

Abstract: There is disclosed a double density recording method for a constant angular velocity type optical disk in which a data information area for recording data information and a servo information area for recording servo control information are provided in recording tracks of the optical disk, pairs of wobble pits for tracking servo control being provided in a staggered form in the servo control area in such a manner that the center axes of the recording tracks are put between the respective pairs of wobble pits, the method being adapted to carry out a subtractive operation of reflected light signals from the respective wobble pits to generate a tracking error signal to thereby conduct a tracking servo control, and to record data information under such a tracking servo control, wherein the respective pair of wobble pits are provided in such a manner that they are shared as wobble pits of adjacent recording tracks, and the wobble pits are provided in a staggered form in a radial direction of the optical disk.

Abstract: An optical disk having a recording format for a sampled servo system and including a servo field which is preformatted, including synchronous marks for synchronizing detection, and a data field for recording data on each track. The length of the synchronous mark is defined to render the detection of the synchronous pattern possible by making it easily distinguishable from the maximum inversion interval in the data even if the optical disk is of the constant-linear-velocity (CLV) type.

Abstract: An optical disk includes: a plurality of recording tracks, each of the recording tracks having a data area for storing data, and a servo control information area for storing servo information; and tracking pits respectively formed on n neighboring recording tracks, which are adjacent to each other in a radial direction of the optical disk, where n is an integer not less than 3. The tracking pits are located in the servo control information area of each of the n neighboring recording tracks and are spaced apart from each other by a distance not less than a radius of a beam spot for reading data from the optical disk. The tracking pits of the n neighboring recording tracks are located on different radial lines of the optical disk.

Abstract: An optical disk having a recording format for a sampled servo system and including a servo field which is preformatted, including synchronous marks for synchronizing detection, and a data field for recording data on each track. The length of the synchronous mark is defined to render the detection of the synchronous pattern possible by making it easily distinguishable from the maximum inversion interval in the data even if the optical disk is of the constant-linear-velocity (CLV) type.

Abstract: An optical disc has a plurality of tracks arranged in a radical direction of the disc. On each track, a plurality of servo areas for recording servo information and a plurality of data areas for recording data information are provided. A heat blocking band is provided between adjacent tracks in the data area for preventing heat from transmitting to the data area.

Abstract: A multi-layered disk which can improve a data recording density and also can record signals and allow reading and reproduction of the recorded signals in good conditions and a recording system as well as a reproducing system using the same and a multi-layered recording disk in which a plurality of data recording surfaces are laminated. In a band wherein, against an MTF level obtained when a read light is on-focus to one of the data recording surfaces, an MTF level obtained when the read light is defocusing to other data recording surfaces is 1/N (N is a real number larger than 1), data signals are recorded in each of the data recording surfaces. A distance t between each data recording surface, numerical aperture NA of an objective lens guiding a read light to any of the data recording surfaces, a wavelength.lambda. of the read light, an equivalent refractive index n between each data recording surface, and a number i of laminated data recording surfaces satisfy the following relation:1.4 n.lambda./(NA).sup.

Abstract: An optical disk with tracks having a sampled servo type recording format, and comprising a preformatted servo field including a synchronous mark for synchronization detection and a data field for recording data on each track. In the optical disk, the synchronous marks are aligned in the same radial direction of the disk per track and have the edge interval longer than the maximum inversion interval of the mark for the data in the track direction, and the interval of the synchronous mark between the adjacent tracks is made smaller than the spot diameter of a reading beam. Hence, in the radial direction of the disk where the synchronous marks are present, the synchronous mark is included in the spot of the reading beam of a pickup irrespective of being on-track or off-track to make it possible to obtain substantially the same level for synchronous signals.

Abstract: A first tracking pit is disposed on one of sides of a track of an optical disc at a position corresponding to a first timing, and a second tracking pit is disposed on the other side of the track at a position corresponding to a second timing. The first tracking pits and the second tracking pits of adjacent two tracks are deflected in a time axis direction.

Abstract: A tracking servo apparatus for an optical disk player enables a braking operation to rapidly draw into tracking servo control even in case of a double density track. The tracking servo apparatus generates an odd/even discrimination signal indicating on which of an odd number track or an even number track a position for reading information by a pick is currently present, samples a tracking error signal according to an edge position of the odd/even discrimination signal, selectively outputs either a positive or a negative section of the tracking error signal according a polarity of the sampled tracking error signal as a brake signal to a driving means for a tracking actuator, and thus draws the position for reading information by a pick-up onto a track which can be put under tracking servo control.

Abstract: A digital signal reproducing apparatus is capable of reproducing digital signals with an accurate sampling clock synchronized with the phase of a read signal. A sequence of predetermined sampled values are detected from sampled values produced by A/D converting a read signal. In this sequence of predetermined sampled values, a difference value of two samples produced at timings spaced apart by a predetermined interval from each other is calculated in order to generate a sampling clock having the phase corrected on the basis of the difference value.

Abstract: An optical disk includes: a plurality of recording tracks, each of the recording tracks having a data area for storing data, and a servo control information area for storing servo information; and tracking pits respectively formed on n neighboring recording tracks, which are adjacent to each other in a radial direction of the optical disk, where n is an integer not less than 3. The tracking pits are located in the servo control information area of each of the n neighboring recording tracks and are spaced apart from each other by a distance not less than a radius of a beam spot for reading data from the optical disk. The tracking pits of the n neighboring recording tracks are located on different radial lines of the optical disk.

Abstract: A transmitting method of digital data whereby information data can be reproduced at a high precision. In order to retain digital data in sectors comprising a plurality of sync frames and sequentially transmit, the sync frame is comprised of the sync signal and the run length limited code which satisfies the limitations of the minimum run length and the maximum run length, and the sync signal includes the sync pattern constituted by a bit pattern of a run length that is longer than the maximum run length by only 3T and addition bit patterns which are arranged before and after the bit pattern and each of which has a urn length that is longer than the minimum run length. The sync signal includes a specific code which indicates a position in the sector and which enables the DC control to be performed.