Abstract: The invention relates to an optical disc for recording data at a constant density, so called CLV (Constant Linear Velocity) or at zoned CLV. The disc has headers distributed along the disc on regular angular positions, a so called CAV (Constant Angular Velocity) pattern subdividing the track in track portions for recording an amount of data proportional to the radical position of the track portion concerned. Address information included in the headers is provided at the data density, which is CLV. The apparatus comprises header detection means for detecting the headers at the CAV locations, and for recovering position information from the headers at CLV density. Data sectors do not start at headers and are not fitted regularly between the headers, but start and stop at arbitrary positions which are calculated from the known amounts of data recordable in the track portion.

Abstract: A record carrier has substantially parallel tracks, which exhibit first variations of a first physical parameter and second variations of a second physical parameter of the track. The first variations represent information recorded on the record carrier, which information is recoverable by means of a controllable type of data processing. A modulation pattern of the second variations represents a code for controlling the type of data processing. With respect to a code track that includes the modulation pattern, the modulation pattern in the left neighboring track is aligned to the modulation pattern in the right neighboring track. Thereby crosstalk due to the second variations in decreased, and at least two tracks have the same modulation pattern. The playback device has a demodulator and a control unit for retrieving the code from at least two tracks.

Abstract: A record carrier is described comprising a servo track indicating an information track intended for recording information blocks represented by marks having lengths expressed in channel bits, which servo track has a periodic variation of a physical parameter. The periodic variation is modulated for encoding record carrier information, such as addresses. The modulation is a bi-phase modulation in which a data bit of the record carrier information is encoded by a first predetermined number of variations of a first phase followed by the same number of variations of a second phase inverse to the first phase. A recording and/or playback device has a demodulator for retrieving data bits of the record carrier information from a first predetermined number of variations of a first phase followed by the same number of variations of a second phase inverse to the first phase.

Abstract: The life of a rewritable information carrier such a CD-E covered by a phase-change recording layer is extended by varying the manner of representing information of an information block, for subsequent recordings, in the same portion of the record carrier. The manner can be changed, for example, by shifting the initial position at which representing information is written along the track over a distance randomly selected within predefined boundaries; or by writing a varying amount of information representing information from the end of the block before the start of information from the beginning of the information block to rotate the information in the track; or by scrambling the information in a varying manner such as using different keys. The manner of representation can be changed, for example, for each subsequent recording on the same portion of the record carrier. This causes different patterns to be recorded in the same portion, even if the same information is recorded in that portion of the track.

Abstract: An information carrier has a pattern of substantially parallel tracks, each track includes a number of sectors and each sector includes an address-information area and an accompanying data area. In the address information areas, the so-called headers, immediately follow the data areas. These headers are composed of at least one address information field and at least one synchronization field and the address information areas in adjacent tracks overlap each other. The address information fields in adjacent tracks are positioned free of overlap relative to each other while adjacent synchronization fields overlap address information fields. This provides a more compact header. Apparatus for reading the information carrier uses a synchronization or a lock-in signal resulting from the reading of the synchronization fields, and the length of the synchronization fields is detected enabling a reliable read-out of the address information fields.

Abstract: An optical record carrier (1) is provided with tracks having a groove (4) wobbled in a radial direction and predetermined positions (18) along the track. Embossed pits (19) at the predetermined positions represent addressing information. The phase of the wobble near the predetermined positions depends on whether a pit is present (19) on a predetermined position or not (20).

Abstract: An optical disk has tracks with a groove wobbled in a radial direction and addressing information at predetermined positions along the track. Embossed pits at the predetermined positions represent addressing information. The phase of the wobble near the predetermined positions depends on whether a pit is present on a predetermined position or not.

Abstract: An optical record carrier has parallel tracks for recording user information in a pattern of optically detectable marks, the tracks being provided with control information. The tracks are grouped in pairs of neighboring tracks. The control information in both tracks of a pair is identical and the control information in tracks of different pairs is different. The identity of the control information reduces the effect of crosstalk on neighboring tracks.

Abstract: A method is described for optimizing recording conditions for writing information on an optical record carrier. The information is written on the record carrier in the form of optically detectable marks, each mark being written by a pulse series of radiation. A series of test patterns is written on the record carrier (1) for the optimization. A jitter detector (11) measures both the leading-edge and trailing-edge jitter of the read signal. The leading-edge jitter is used to optimize the value of a parameter influencing only the leading part of a pulse series. The trailing-edge jitter is used to optimize a parameter influencing only the trailing part of the pulse series.

Abstract: A disc-shaped information carrier has a track thereon which follows a helical or concentric path forming successive windings. For identifying each winding the information carrier also has a servo pattern thereon which includes position-information as well as synchronization elements. Such elements may be, for example, brief pulses in a continuous track wobble, and are distinguishable in adjacent windings based on a predetermined detectable parameter, such as alternating polarity or shifted relative phase positions. During recording by a read/write head a system control detects the synchronization elements and monitors whether a deviation has occurred signifying that the read/write head has wandered to an adjacent winding. In that event recording is interrupted. Thus, the least possible information in adjacent windings is overwritten in the case of disturbances resulting from shocks or defects of the information carrier.

Abstract: The device according to the invention is suitable for recording a rewritable information carrier such a CD-E covered by a phase-change recording layer. As is known, such an information carrier has a limited useful life because the recorded, optically readable patterns start deviating ever more from the desired form when recorded recurrently. The invention is also based on the recognition that this degradation is accelerated if a certain part of the track on the information carrier constantly accommnodates the same patterns, for example, if information blocks are recorded starting from fixed initial positions and the information is represented by the patterns in a specific manner. The device comprises means for shifting the initial position along the track over a distance randomly selected within predefined boundaries and/or for adapting the manner of representation. This causes constantly different patterns to be recorded, even if the same information is to be recorded in a specific part of the track.

Abstract: A disc-shaped information carrier and a device for reading and/or writing information blocks in a track thereon which follows a helical or concentric path forming successive windings. For identifying each winding the information carrier also has a servo pattern thereon which includes position-information as well as synchronization elements. Such elements may be, for example, brief pulses in a continuous track wobble, and are distinguishable in adjacent windings based on a predetermined detectable parameter, such as alternating polarity or shifted relative phase positions. The device has a read/write head and a system control which during writing detects the synchronization elements and monitors whether a deviation has occurred signifying that the read/write head has wandered to an adjacent winding. In that event writing is interrupted. Thus, the least possible information in adjacent windings is overwritten in the case of disturbances resulting from shocks or defects of the information carrier.

Abstract: An optical recording medium having a recording layer with grooves that define recording tracks. The structure of unwritten tracks enable a scanning device to derive a radial tracking error signal using the push-pull method. The structure of the written tracks enable the scanning device to derive a radial tracking error signal using the high-frequency phase-detection method. The width of the groove is in the range from 0.3 to 0.6 time the wavelength over the numerical aperture for scanning the recording medium. The depth of the groove is in the range from 1/24 to 1/7 times the wavelength for scanning the recording medium. The phase difference between a radiation beam reflected from a track at a mark and a radiation beam reflected from that track in a region between written marks is in the range from 0.4 to 2.0 radians.

Abstract: An optical recording medium containing control information to set the write power at an optimum level for recording information on the medium. The control information includes a preset value of the derivative of the modulation of a read signal with respect to the write power. The optimum write power is derived from values of the modulation measured from test patterns on the medium and the preset value recorded on the medium.

Abstract: A method is described for recording an optical information carrier, in which marks representing recorded data are written at different writing speeds by radiation pulse of equal length and power, independent of the writing speed. The number of pulses per unit length of the written mark is a constant independent of the writing speed.

Abstract: Disclosure is given of a device and method for recording by means of a radiation beam user information on a record carrier. The user information is written in the form of optically detectable marks in concentric tracks. The tracks are subdivided into sectors. The record carrier used has ring-shaped zones. Within these zones lie the sectors aligned seen in radial direction. For writing the marks in the tracks, a write intensity of the radiation beam is set to a determined set value. For this purpose, a test information pattern is written in a buffer sector which is situated on an edge of a zone. Then the test information pattern is read back during which operation the test information pattern is converted to a corresponding test data pattern. Based upon the test data pattern a set value for the write intensity is determined.

Abstract: A magneto-optical record carrier having a recording track structure which enables recording with an increased information density. Information areas which are smaller than the write spot supplied by a first diode laser can be written by means of a switched magnetic field. The areas can then be read with a read spot which is smaller than the write spot, which read spot is formed by radiation from, for example, the combination of a second diode laser and a frequency doubler. The width of the recording tracks determines the width of the information areas recorded thereon.

Abstract: A method and device for recording signals on a record carrier with the aid of a radiation beam (15). The signals are recorded in the form of optically detectable marks in parallel tracks which have a substantially constant track pitch. The recording intensity of the radiation beam is set in such a way that with a "minimum" recording intensity information patterns are recorded with a low desired error rate "(Block) Error Rate". Furthermore, a method and device are described by which the "minimum" recording intensity of the radiation beam can be determined.

Abstract: An apparatus for writing and reading a magneto-optical record carrier (1) with an increased information density are described. Information areas (4) which are smaller than the write spot (V.sub.w) supplied by a first diode laser (40) can be written by a switched magnetic field. The areas can be read with a read spot (V.sub.r) which is smaller than the write spot, which read spot is formed by radiation from, for example an assembly of a second diode laser (42) and a frequency doubler (43).

Abstract: A method and apparatus for writing and reading information in the form of a pattern of magnetic domains in an information layer of a record carrier. An optical scanning beam is focused to a diffraction-limited radiation spot, and a magnetic field is generated by a coil supplied with an energizing current the amplitude of which is modulated by the information signal to be recorded. The magnetic field is thereby modulated, and produces magnetic domains in the information layer such that each domain has a variable number of sub-domains and consequently a variable magnetization ratio, as determined by the information signal. This permits recording at an information density exceeding that corresponding to the size of the radiation spot.