U.S. Philips Corporation

U.S. Phillips Corporation

Jacobus P Heemskerk

Peter Coops

Rudolf Roth

Derk Visser

Antonius H Holtslag

Kornelis A Immink

Carel Arthur Simons

Hindrik Veldhuis

Martinus P Bierhoff

Jan G Dil

Hendrik Renes

A system for controlled reproduction of information according to the invention comprises an information carrier and a reading device. The information carrier contains information in blocks written in a track. The information carrier has reference patterns which divide the track into sectors for writing the information blocks, and auxiliary information written in the reference patterns. The auxiliary information is related to the information, for example, a decoding key, access code or digital signature. The reading device comprises a demodulation means for recovering both the information and the auxiliary information. The device may include means for processing the information and/or auxiliary information in dependence on the auxiliary information. Since the auxiliary information cannot be transferred to an illegal copy, this copy is unusable.

Information carrier containing auxiliary information, reading device and

An optical information storage system has a multi-recording-layer record carrier and a scanner device for the carrier. The scanner produces a radiation beam which is compensated for spherical aberration for a single height of the scanning spot with the stack of layers. The height of the stack is determined by the maximum spherical aberration permissible for the system. The number of layers in the stack is determined by the minimum distance between layers, which depends on the crosstalk in the error signals due to currently unscanned layers.

Multi-layer information storage system with improved aberration

An optical information storage system has a multi-recording layer record carrier and a scanner device for the carrier. The scanner produces a radiation beam which is compensated for spherical aberration for a single height of the scanning spot with the stack of layers. The height of the stack is determined by the maximum spherical aberration permissible for the system. The number of layers in the stack is determined by the minimum distance between layers, which depends on the crosstalk in the error signals due to currently unscanned layers.

Methods of and information recording devices for recording and/or inhibiting recording of a signal including copy bits on a record carrier, and a record carrier including that signal. The signal has successive information frames including main data and subcode data. The subcode data of the information frames make up successive subcode frames having copy bits with logic values which alternate among the subcode frames in accordance with a predetermined pattern. Each subcode frame has at least one copy bit. In one of the embodiments, the signal is received and a determination is made whether to inhibit its recording on the basis of the predetermined pattern exhibited by the logic values of the copy bits contained in the subcode frames. In another embodiment the subcode frames are replaced by substitute subcode frames having copy bits with logic values which alternate among the substitute subcode frames in accordance with a selected pattern prior to recording of the signal. The predetermined and selected patterns are indicative of a particular characteristic of the main data (e.g., whether the main data is copy protected).

Methods of and information recording devices for recording and/or

Record carrier with copy bits

An apparatus is described for optically scanning an information surface (2). The apparatus comprises a radiation source (4), an objective system (6) and, arranged between them, a diffraction grating (9) for separating the beam reflected by the information surface from the beam (5) emitted by the source and for splitting the reflected beam into two sub-beams (5a, 5b). For each sub-beam there is provided an associated detector pair (16, 17; 18, 19). The grating (9) comprises two sub-gratings (11 and 12) whose grating lines (13, 14) are disposed at opposite angles to the bounding line (26) of the sub-gratings.

Apparatus for optically scanning an information plane wherein a

An optical read unit is described for scanning a record carrier with a radiation-reflecting trackwise-arranged information structure. The read unit utilizes a diode laser which generates the read beam and also detects the information stored on the record carrier. The read unit is also provided with an opto-electronic system for detecting the position of the read spot relative to a track to be read and the position of the plane of focussing. The diode is mounted in a housing and the unit includes electromechanical apparatus for moving the housing in two perpendicular directions so as to correct the position of the read spot. The objective system for the formation of the read spot is of simple construction.

Optic read unit for scanning a record carrier having a

A focussing error detection system is described for determining deviations between the plane of imaging of an objective system in an optical arrangement and the radiation-reflecting surface in said system. The apparatus comprises an optical element by means of which a radiation beam coming from the radiation reflecting surface is both rendered astigmatic and separated from a radiation beam which is directed to the radiation-reflecting surface. By the use of this element the number of components of the focussing-error detection system can be minimized and a compact construction of said system can be obtained.

Optical focussing-error detection system

A focusing system for focusing a radiation beam onto an object, in particular an optical disc. The focusing system comprises focusing-error detection means and two control elements for correcting the focusing depending on the detected focusing error. The detection means are constructed so that via one of the two control elements a feedback servo system is obtained while via the other control element a servo system without feedback, i.e. a feed-forward system, is obtained.

Optical focusing device with two controls

A record carrier is disclosed having an optically readable information structure comprising trackwise arranged information areas, as well as an apparatus for reading said record carrier. By using two mutually perpendicularly polarized beams components for reading and by giving the information areas of adjacent track portions a different geometries such that areas of one geometry can be read in an optimum manner by only one of the beam components and is virtually not observed by the other beam component, the track distance can be reduced without increasing the crosstalk, so that the information content of the record carrier is increased.

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Eindhoven, Netherlands

Jacobus P Heemskerk