Abstract: An optical data storage medium (1) is described. The medium (1) has an optically readable information layer with a first optical reflectivity. An annular zone (12), outside the user data recording area (2) has at least one first type (5) of sector provided with a permanent information mark (7), having a second optical reflectivity. The zone has at least one second type (6) of sector provided with a recordable identification mark (8), having a third optical reflectivity different from the first optical reflectivity. Thus, a hybrid bar code like structure, with both permanent and recordable information requiring little radial space, is provided. Further, methods to read such permanent information marks (7)/recordable identification marks (8) and to write such recordable identifications marks (8) are disclosed.

Abstract: The present invention relates to a multilayer record carrier, to a recording apparatus and to a method of recording on such a multilayer record carrier, and to a manufacturing method, wherein start and stop positions of recording areas at header portions (H) are shifted in a lower recording layer (8) by a predetermined distance (&Dgr;) such that recording and reading in/from the lower layer (8) is not affected by a variation in the transmittivity of the upper layer (6) at the transitions between the recording areas (R) and the header portions. The shifting may be obtained by extending gap portions or adding mirror areas to the header portions (H).

Abstract: The present invention provides for a matrix display device (10) and related method of controlling light output from such a device employing sub-field addressing (14) and comprising determining the display load of the device (10), and further including the steps of dynamically varying the number of sub-fields available for display of an image responsive to said display load being determined (16) to be below a threshold value and advantageously employing partial line doubling and/or dithering (22,24) for at least the least significant bits of the display signal.

Abstract: The present invention relates to a multilayer record carrier, a recording apparatus and a method of recording on such a multilayer record carrier, wherein a difference in a transmission property of an upper information layer (6) is detected, and a corrected power value is used for recording on a lower information layer (8) at positions where the difference has been detected. The corrected power value is determined on the basis of the detected difference or a specification provided on the multilayer record carrier. Thereby, the recording power level or margin can thus be maintained during the recording on the lower information layer (8), that is, even in cases where the recording is effected through header areas (H) or gap portions (RO, RI) in the upper information layer (6).

Abstract: The present invention relates to a multilayer record carrier and method of manufacturing thereof and recording thereon, wherein data is written in units of blocks on tracks of at least two information layers. A first guard field is written at the start of a data block and a second guard field is written at the end of the data block. The power in the focussed spot in the deepest of said at least two information layers is maintained substantially at an optimal value, by setting the length of the first and second guard fields such that the end position of the second guard field of a preceding data block is located within the area of the first guard field of the succeeding data block. Thereby, gap portions between the first and second guard fields can be prevented.

Abstract: The invention relates to a predetermined synchronization pattern (40), a so-called VFO field, in, for example, the headers 3 of an information carrier. The proposed predetermined synchronization pattern (40) consists of sequences of 3T marks and spaces (41), of 8T marks and spaces (42) and of 5T marks and spaces (43). This sequence of patterns is advantageous for setting the dynamic range of an Automatic Gain Controlled (AGC) amplifier located within a device reading the information carrier.

Abstract: The invention relates to an additional information field DI in at least a group of headers 3 on an information carrier. The additional information field may be used to store information describing properties of the information carrier. This information can be stored in an information field DI of a single header or, alternatively, in the information fields DI of a sub-group of headers 3. When no information field DI is present in a second group of headers, a second synchronization field VFO2 may replace the information field DI.

Abstract: A method for writing an optical record carrier, in which a mark representing recorded data is written in the record carrier by a sequence of radiation pulses. The radiation power has a different level in between the pulses of a sequence and immediately after the last pulses of a sequence. This allows an independent control of the leading and trailing edge jitter of the marks written.

Abstract: An optical record carrier is described comprising a track for carrying data encoded in optical marks. A parameter of the track has a periodic variation for generating a varying signal when scanning the track, for example a variation of the center of a pre-groove usually called wobble. The track further comprises reference elements, e.g. headers, interrupting the periodic variation. The phase of the periodic variation after the reference elements is indicative of a property of the record carrier for controlling the scanning of the record carrier in dependence of said property. In particular the phase may indicate whether or not the bottom of the pre-groove is closer to the scanning beam entry side of the disc. Further a scanning device is described comprising a detector for detecting said phase based on the varying signal. The device adapts its scanning control means to the indicated property.