摘要:
This apparatus relates to a data carrier which rotates about an axis and on which a track is provided for containing said data, said track spiraling around a center, which apparatus comprises an angle measurer for many purposes. For obtaining this angular position information, for example an eccentricity measurer is used. The eccentricity is defined by the non-coincidence of the center and the axis. Application: The invention is well suited to small-size optical discs, CD systems, DVD systems, and Blu-Ray systems.
摘要:
When writing data to an optic disc with a constant linear velocity, and encountering a disc error, data is written into the defect management area of the disc without changing the rotational speed of the disc, or at least without changing the rotational speed of the disc sufficiently to maintain a constant linear velocity. This allows an increase in the rate at which data may be written to the optical disc. It also avoids or reduces the need for the rotational speed of the disc to be changed, which allows a further improvement in the time taken to write data to the disc. In order to continue writing data to the disc without changing the rotational speed, the data rate must be increased while writing to the defect management area. For this to be possible, the data must be written into an “iced” or unformatted part of the defect management area.
摘要:
An ECC block is constituted by RS(248,216,33). Of a data length of 216 bytes (symbols), only 16 bytes are allocated to BCA data and the remaining 200 bytes are used for fixed data having a predetermined value. Using the fixed data of 200 bytes and the BCA data of 16 bytes, parities of 32 bytes (symbols) are calculated. Only the BCA data of 16 bytes and the parities of the former 16 bytes of the 32-byte parities, that is, a total of 32 bytes only, are recorded in a burst cutting area of an optical disc. In decoding, error correction processing is carried out by using the fixed data of 200 bytes. The unrecorded parities of 16 bytes are processed as having been erased. Thus, the error correction capability in a burst cutting area of an optical disc can be improved.
摘要:
A record carrier (1) has a servo track (4) indicating an information track (9) intended for recording information blocks represented by marks, this servo track (4) having a periodic variation of a physical parameter. Due to cross-talk, there exists a variation in the wobble signal called wobble beat. The track pitch t and the wobble period p, p being the length of a wobble period, are chosen in such a way that 2πt/p≈n+½ where n is integer. The choice results in a reduced wobble beat. A recording and/or playback device has apparatus for recording/reading the information blocks and for generating a wobble signal.
摘要:
The S/N ratio is improved for recording data to grooves (2-1,2-2) of an optical disc so that as much information as possible can be recorded at the lowest possible frequency band. An optical disc using wobble patterns to record different information has a first groove (2-1) having a first wobble pattern (22) in which one wobble period has a sharp rising edge and a gradual falling edge; and a second groove (2-2) having a second wobble pattern (24) in which one wobble period has a gradual rising edge and a sharp falling edge. Each of the first and the second wobble pattern is represented by a first fundamental and a second harmonic of a Fourier series. The polarity of the second harmonic, which is an even harmonic, of the second wobble pattern is opposite that of the first wobble pattern. A method for manufacturing this optical disc is also provided.
摘要:
An optical disc medium 10 having a wobbled track groove 12 includes three wobble patterns including a flat wobble pattern, a positive pulse wobble pattern, and a negative pulse wobble pattern. In the flat wobble pattern, the amplitude of the wobble from the lengthwise direction of the track groove is zero such that the track groove is flat. In the positive pulse wobble pattern, the amplitude of the wobble from the lengthwise direction of the track groove is positive such that the track groove is wobbled in a first direction perpendicular to the lengthwise direction. Further, in the negative pulse wobble pattern, the amplitude of the wobble from the lengthwise direction of the track groove is negative such that the track groove is wobbled in a second direction opposite to the first direction. Then, three data values can be recorded using three distinctive wobble patterns.
摘要:
A method of storing/retrieving information to/from an optical disc by means of an optical system with a cut-off frequency νcut-off, above which frequencies cannot be detected, is disclosed. The invention relates to Run Length Limited encoded information. According to the invention, some frequencies of the encoded information can be higher than cut-off frequency of the optical system, such that the equation 4*(d+1)*Lcd*NA/λlaser
摘要:
A wobble signal is generated from at least two elementary signals (A,B,C,D) detected by scanning a wobbled track of a data carrier. The invention proposes a solution for eliminating the noise of various origins in the wobble signal, notably the high frequency data leakage into the wobble signal due to radial asymmetry introduced in the diffraction pattern on the detector, whatever the reason for this radial asymmetry. According to the invention, the at least two elementary signals are filtered with at least an adaptive filter (40), and said filtered elementary signals are subtracted (44) from said wobble signal (PP) thereby generating an improved wobble signal.
摘要:
The invention relates to a method of encoding user data into codevectors and to a corresponding method of decoding codevectors into user data. In order to be able to use the same ECC decoder for decoding of more than one type of data a method of encoding is proposed comprising the steps of: a) generating a first block of a fixed first number of data symbols by taking a fixed second number, being smaller than said first number, of user data symbols, and a fixed third number of dummy data symbols, and by arranging said user data symbols and said dummy data symbols in a predetermined order, b) encoding said first block of data symbols using an ECC encoder (2) to obtain a codeword having a fixed number of symbols, said codeword comprising said first block of data symbols and a second block of a fixed forth number of parity symbols, and (c) generating a codevector by selecting a fifth predetermined number of user data symbols and a sixth predetermined number of parity symbols from said codeword, the sum of said fifth and sixth number being predetermined and smaller than the sum of said second and forth number.
摘要:
A method for manufacturing a record carrier and a record carrier comprising an optical disc having a lead-in portion storing information being indicative that a fixed relation is provided between the physical address of each error correction code (ECC) block and the corresponding position of each ECC block on the disc. Provides the possibility of fast access to the ECC blocks on the disc for recording and/or reading of data. May easily be applied to existing groove-only formats, such as CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-R, DVD+R, DVD-RW, DVD+RW, and is therefore ‘backward compatible’. Furthermore, a device for recording and/or reading data on/from a record carrier. Is capable of reading the information in the lead-in portion and act accordingly, i.e. fast access if it is possible and normal access if not.