Deutsche Thomson-brandt Gmbh

Thomson Consumer Electronics Inc.

Thomson Licensing

Dietmar Uhde

Gunter Gleim

Hartmut Richter

Jurgen Kaaden

Fritz Weisser

Paul-Louis Meunier

Hartmut Schandl

Alain Staron

Peter Hoch

Rudiger Lehmann

Philippe Compoint

Ernst F Schroder

Friedhelm Zucker

Heinz-Werner Keesen

Klaus Oldermann

Jens Spille

Hans-Joachim Platte

Christian Buchler

Arthur Kurz

Heinz-Joerg Schroeder

Rolf Schiering

Franz Bigge

The present invention relates to an optical recording medium having at least two information carrier layers, on which information can be written by means of a focused light beam. In this case, a separating layer is arranged between the information carrier layers and a respective transparent covering layer is arranged between the information carrier layer and the surface of the recording medium, the thickness of which covering layer substantially exceeds that of the information carrier layer. One object of the present invention is to propose an optical recording medium in the case of which it is possible to write to both information carrier layers using a low optical power. Further objects of the invention are to specify an apparatus and also a suitable method for writing to a recording medium of this type. A recording medium according to the invention has information carrier layers which are both semi-transparent.

Optical recording medium having at least two recordable layers

An optical recording medium having at least two information carrier layers, on which information can be written by means of a focused light beam. In the present invention, a separating layer is arranged between the information carrier layers and a respective transparent covering layer is arranged between the information carrier layer and the surface of the recording medium, the thickness of each transparent covering layer substantially exceeds that of the respective information carrier layer. One object of the present invention is to propose an optical recording medium in the which it is possible to write to both information carrier layers using a low optical power. Further objects of the invention are to specify an apparatus and also a suitable method for writing to recording medium according to the present invention. A recording medium according to the invention has information carrier layers which are both semi-transparent.

Recording or reproducing unit for a plate-shaped information medium including an improved autobalancer for compensating an unbalance. The autobalancer for compensating an unbalance is arranged in the hold-down for a plate-shaped information medium at a diameter greater than an inside scanning diameter, required for scanning, of the information medium and is formed by at least one disc in a circularly running groove forming the means for compensating an unbalance.

Recording or reproducing unit with means for compensating the unbalance of plate-shaped information media

A device for reading from and/or writing to optical recording media, including a beam generator, a focus device, which focuses the beam generated onto the optical recording medium at a focal point, a displacement device, which displaces the position of the focal point on the recording medium in accordance with a first direction of movement in dependence on an actuating signal, and a detector, which detects a beam reflected from the optical recording medium and outputs a regulating signal to a regulator. The regulator generates an actuating signal for the displacement device. The invention allows a higher data transfer rate to be achieved with an acceptable outlay. This is achieved by a beam influencing device arranged in the beam path and, in dependence on a further actuating signal of the regulator, influences the position of the focal point on the recording medium in accordance with the first direction of movement.

Device for reading from or writing to optical recording media

Apparatus for interposing additional optical elements in the optical path of an optical read/write device includes said additional element mounted on a carrier pivotally mounted on a lens carrier which is subject to lateral translation. Stops on the carrier to which the additional element is mounted engage actuators arranged at the limits of lateral travel of the lens carrier, which limits are beyond the recordable areas of the recording medium. The engagement of the actuators with the carrier causes the carrier to pivot and either insert or remove the additional optical element in the optical path of the apparatus. Magnetic retainers are included to prevent the additional element from moving from the desired position.

Optical disk apparatus with means to selectably insert additional

A receiver/recorder for television transmissions whereby continuous recording of television transmission occurs from at least one channel onto a random-access rewritable recording medium. At each of a plurality of predetermined locations a binary code is periodically written to represent a filling of predetermined portions corresponding respectively to the predetermined locations. An indexing device responds to the binary code in order to automatically distinguish between a first in time recorded transmission on the medium from a second in time recorded transmission on the medium at a particular one of the predetermined locations.

Receiver/recorder of television transmissions

A cassette for use with a recording apparatus comprises: a housing for a recording medium, the housing having a first surface and side walls, the recording medium being accessible through one of the side walls; at least a part of a chip card affixed to the housing, forming a second surface of the housing and closing the cassette, the chip card part having a memory formed integrally therewith and externally accessible contacts; and, the contacts of the chip card being positioned on the second surface to be engageable by corresponding contacts in the recording apparatus when the cassette is inserted therein. One of the side walls has an access door for the recording medium and the second surface forms an upper wall of the housing as defined by the access door. The part of the chip card forming the second surface of the housing has a marking position at which light transmissivity can be controlled. The marking position can be rendered non transmissive to light to prevent recording.

Cassette including a recording medium for a recording apparatus

A receiver/recorder of television transmissions is disclosed which operates automatically on a stand-by basis to record continuously television transmissions from at least one channel onto a reusable large capacity recording medium such as a magnetooptic disk. The recording is accomplished without user intervention and the system includes an indexing for distinguishing a recent recording from an older recording which is partially overlapped by the recent recording.

Continuous television transmission reproduction and playback

A digital recorder which includes an A/D converter for converting analog signal to digital form for recording and a D/A converter for converting recovered recorded digital information to analog form, includes switch circuitry for interconnecting the D/A converter and the A/D converter in a manner to perform sample rate conversion of input digital signals to condition the recorder to record digital signals having different sample rates.

Digital recording and reproduction device

A drum for a rotatable cylinder head includes an opaque disc-shaped member having a plurality of opaque fins affixed thereto and arranged substantially normal to the disc-shaped member. A first plurality of the fins has a first width and a second plurality of the fins has a second width broader than the first width. Every fin has a distal end remote from the disc-shaped member, and an opaque circumferential ring is affixed to the distal end of each fin. The disc-shaped member, the fins and the circumferential ring form a plurality of apertures about the drum.

Head cylinder for a recorder

A process for producing a thin-film magnetic tape head includes the steps of coating a substrate with a layer of material which protects the substrate from an etchant. A cavity is etched into the substrate and a prismoid of magnet material is deposited in the cavity. The sides of the substrate are removed so that the prismoid projects above the sides for a substantial portion of the height of the prismoid. The substrate is coated with a gap-coating layer and the gap-coating is removed from one side of the prismoid. Another layer of magnetic material is deposited onto the substrate and various parts, such as pole shoes, are formed. The substrate is polished and the apex of the prismoid is removed. Head windings are made. A return path for the head windings is provided by depositing another layer of magnetic material onto the substrate. A protective layer of a metal oxide is deposited onto the substrate.

Process for producing a thin-film magnetic tape head

A digital signal, such as obtained during playback from a DAT machine, includes a first component containing e.g. the audio content and a second component containing error recognition code. A signal processor derives in accordance with the second component an error signal representative of errors in the digital signal. A microcomputer then calculates an error rate signal. The error rate signal may be visually displayed or the error rate signal may be applied to the pre-amplifier circuits in the playback transducer stage to minimize the errors.

Apparatus relating to the reproduction of error encoded digitally

Several signal sources that produce corresponding digitally coded signals are coupled to a selection circuit. A microprocessor controls signal selection switches that select one of the signal sources in accordance with a priority schedule, provided that the signal source produces a signal at a frequency that is within a predetermined range of frequencies. The selected signal is then recorded in a tape recorder or forwarded to a signal reproducer device. To test whether a given signal source generates a signal at a frequency that is suitable for recording or reproducing purposes, the digitally coded signals from that source is coupled to an input of a phase-lock-loop circuit (PLL). When the signal causes a lock-in condition in the PLL, that signal source is then selected. If the lock-in condition does not occur, the test is applied to another signal source that is next in the priority schedule.

Signal selection arrangement

Apparatus for selectively playing back and recording data on a disk in

A method of controlling the number of revolutions of a motor using the output of a tachogenerator, which determines the number of revolutions of the rotor, to regulate the motor. To improve the accuracy of such prior art regulating methods, which are limited by the mechanical tolerances of the tachogenerator elements, the actual time differences between pulses corresponding to respective fixed points on the rotor circumference during a revolution of the rotor are measured. The sequence of the pulses constituting the actual time differences is compared with a desired time difference sequence and a signal to control the driving motor is derived from this comparison.

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Konigsfeld, Germany

Dietmar Uhde