Abstract: A switchable diaphragm (9) and a device for beam deflection (10) are placed in the servo branch of an optical drive, in a path of light beams of different diffraction orders. This permits redirection of light beam orders towards a detection means (8) on an individual basis and selection of light orders at a detection means (8) depending on requirements. The number of detectors in the device detection means (8) can thus be reduced, thereby also reducing additional components associated with those detectors and saving on cost and complexity. With such device functionality, new methods for measuring beam landing and spherical aberration are developed.

Abstract: The present invention relates to a device in a corresponding method for encoding a secondary information (r) of a secondary channel into a channel data stream (3) of a primary channel, said channel data stream (3) comprising at least two symbol rows of channel symbols one-dimensionally evolving along a first direction (t) and aligned with each other along a second direction (r), said two directions constituting a two-dimensional lattice of symbol positions.

Abstract: The invention regards a new threshold crossing timing recovery scheme for use in high capacity optical disc systems. The timing error of a timing error detector is multiplied with a weighing function. This scheme effectively increases the robustness of the optical system against data-induced jitter, which is considered to be the dominant disturbance of the timing recovery as the capacity of the optical discs is high. The invention furthermore describes a number of examples of possible weighing functions.

Abstract: In modem optical disc systems, inter-track spacing is chosen relatively small in order to allow high storage densities. As a result, the optical spot has a radius comparable with the track pitch, and the data written on neighboring tracks appear in the target track signal in the form of inter-track interference (cross-talk). To tackle the cross-talk problem, cross-talk canceling schemes are normally employed. These schemes use three spots, one spot on the main track and two satellite spots on adjacent tracks. The read signal (C) is improved by minimizing the cross-talk between the satellite signals (S+,S?) and the read signal (C). However, due to the decreasing inter-track spacing, the decorrelation concept fails since the satellite spots read too much central track information and become strongly correlated with the read signal (C), which causes “leakage” in the decorrelation.

Abstract: A driver for driving a light generator for generating light, comprising a digitalto-analog converter (DAC) having a data input, a data output for generating an analog signal, a first multiplexer (MUX1) for cyclic selection of a number of data levels corresponding to desired intensity levels of the light and for coupling the data levels to the data input; a de multiplexer (DE-MUX) synchronized with the first multiplexer (MUX1) for de-multiplexing the analog signal into a set of analog signals; memory means for temporarily storing the set of analog signals; and a second multiplexer (MUX2) for selection of the stored set of analog signals and for generating a drive signal (IL) for the light generator. The memory means is preferably implemented by a set of capacitors (C1-C8). Usually, for instance in an optical disc drive, the light generator is implemented by a laser (Ls).

Abstract: The present invention relates to a symbol detection apparatus for detecting the symbol values of a two-dimensional channel data stream recorded on a record carrier, said channel data stream comprising a set of contiguous symbol strips (B) of symbol rows (r) onedimensionally evolving along a first direction and being aligned with each other along a second direction, said two directions constituting a two-dimensional lattice of symbol positions.

Abstract: A recording apparatus for recording channel symbols of a channel data stream on a record carrier (50), said apparatus being adapted for recording said channel symbols as a channel band (cb) of at least two symbol rows (sr) one-dimensionally evolving along a first direction (t) and aligned with each other along a second direction (r), said two directions constituting a two-dimensional lattice of symbol cells (sc) each being associated with a symbol area (sa) of the record carrier (50).

Abstract: When processing a two dimensional data area it is known to be advantageous to divide the two dimensional are into stripes and process each stripe using a stripe-wise detector. The stripe being processed shifts row per row downwards. Each stripe has as its output the bit-decisions of the top bit-row of the stripe which is the most reliable. That output bit-row is also used as side-information for the bit detection of the next stripe which is the stripe which is shifted one bit-row downwards. The bit-row just across the bottom of the stripe on the other hand still needs to be determined in the current iteration, so only the initialisation bit-values can be used in the first iteration of the stripe-wise bit-detector. In order to prevent the propagation of errors towards the top bit row of the stripe the relative weight for the bottom branch bit in the figure-of-merit is reduced from the full 100% to a lower fraction.

Abstract: The present invention relates to an encoding apparatus and a corresponding method for two-dimensionally encoding user data of a user data stream into channel data of a channel data stream along a two-dimensional channel strip of at least two bit rows one-dimensionally evolving along a first direction and being aligned with each other along a second direction, said two directions constituting a two-dimensional lattice of bit positions. According to the invention the apparatus comprises a modulation code encoder for modulation code encoding said user data into said channel data according to a two-dimensional modulation code being adapted to prevent predetermined worst case patterns of channel data in said channel data stream. The worst-case patterns are typical for high-density two-dimensional optical storage channels.

Abstract: The present invention relates to a method for synchronizing the signals coming from a set of data channels of a two dimensional optical read-out system. Said synchronization method comprises a step of cross-correlating the signals of a pair of adjacent channels for determining a relative phase delay between said adjacent channels. It also comprises a step of iterating the cross-correlation step for the different pair of adjacent channels of the set of data channels. It finally comprises a step of compensating for the relative phase delays thus obtained in order to align the signals from adjacent channels with each other. The present invention is based on, for example, the use of the optical cross talk existing between adjacent channels in a cross correlator that is able to determine the relative phase between two adjacent channels.

Abstract: Disclosed is a bit-detection arrangement able to convert an analog signal (AS) having an amplitude into a digital signal (DS) representing a bit sequence from which the analog signal (AS) is derived. The bit-detection arrangement has a phase detector which detect the phase difference between a quantized analog signal and a clock signal C2. The phase difference is sampled by an AD converter. The AD converter can sample at a relatively slow rate as the phase difference is a low frequency signal. The sampled phase difference is fed to a digital PLL which outputs a phase signal PHI. The phase signal and the quantized analog signal are used to recreate the digital signal (DS).

Abstract: When processing a two dimensional data area it is known to be advantageous to divide the two dimensional are into stripes and process each stripe using a stripe-wise detector. When processing a data area delimited by more than one guard band it is advantageous to start a subset of bit detectors from each guard band in order to propagate the improved reliability of the side information obtained from the guard band through the subset of detectors. Because the subsets can start processing at the same time the overall detection delay is reduced.

Abstract: An optical disc drive apparatus (1) comprises a laser device (30) for generating a light beam (31) for optically reading data from a disc (2). Said laser device (30) is electrically incorporated in a resonant circuit (70), which comprises an inductance (L) coupled to said laser device (30).

Abstract: The present invention relates to a method of determining write parameters for recording information on a record carrier, said information being in the form of a multidimensional channel data stream to be recorded as a channel band of at least two symbol rows one-dimensionally evolving along a first direction and aligned with each other along a second direction.

Abstract: The present invention relates to a coding strategy for joint modulation coding and ECC coding. It relates in particular to the situation where 2D coding is performed along one-dimensionally evolving strips containing a number of bit rows in the radial direction of the strip, which is orthogonal to the former direction. The idea further relates to high-rate modulation coding. According to the invention, a strip is built up by an alternation of two basic sub-units, each with their own modulation code. The first sub-unit comprises a larger number of bit rows, and its (high-rate) modulation code has a high coding efficiency realized through the use of large codewords.

Abstract: The invention relates to an information recording apparatus intended to record information on an optical medium by forming series of recorded marks whose length between leading edge and trailing edge corresponds to a binary value by irradiation means with a beam of light. According to the invention, said irradiation means are sequentially pulsed to at least a high laser current write level from a low laser current level LL close to zero during the writing of a recorded mark. The invention enables to lower the average laser current during writing and also erasing. As a consequence the power dissipation is lowered. Application: Information recording apparatus, especially for SFFO, BluRay standards.

Abstract: A servo system comprising an analog sigma delta modulator for generating a normalized digital error correction signal from first and second analog control signals. The sigma delta modulator comprises an analog low-pass filter, a quantizer delivering the digital error correction signal and a multiplying DA-converter in feedback arrangement between the output of the quantizer and the input of the low-pass filter for multiplying the feedback signals with the sum of the analog control signals.

Abstract: The present invention relates to a bit detector for detecting the bit values of bits of a channel data stream stored on a record carrier, wherein the channel data stream comprises a channel strip of at least two bit rows one-dimensionally evolving along a first direction and aligned with each other along a second direction, said two directions constituting a two-dimensional lattice of bit positions.

Abstract: The present invention relates to a method and an apparatus for reading a magneto-optical domain expansion recording medium (10) wherein the size of a spatial copy window of a domain copying process is controlled in that a predetermined reading parameter is varied in response to a control information derived from a readout pulse, and in that a predetermined additional pattern of change is applied to said predetermined parameter. A decision level pattern used for deciding on a readout value is adjusted in dependence on a characteristic parameter of said additional change pattern. Thereby, signal detection errors can be reduced so that storage density is improved significantly.

Abstract: The present invention relates to a Viterbi bit detection method for detecting the bit values of bits of a channel data stream stored on a record carrier along an N-dimensional channel tube, N being at least two, of at least two bit rows one-dimensionally evolving along a first direction and being aligned with each other along at least a second of N-1 other directions, said first direction together with said N-1 other directions constituting an N-dimensional lattice of bit positions, comprising application of a row-based one-dimensional Viterbi bit detection method independent for each of the bit rows of said channel tube.