Thomson-csf

Thales

Thomson Consumer Electronics Inc.

Thomson Multimedia S.a.

Joseph Colineau

Michel Audoin

Charaf Hanna

Michel Sonrier

Jean-Claude Lehureau

Jean-Marc Coutellier

Thierry Valet

Francedillaois Maurice

Jean-Pierre Huignard

Jurgen Machui

Arnaud Brignon

Christian Claudepierre

Francois Maurice

Sophie Neubert

Mario De Vito

Francois X Pirot

Cindy Bellanger

Bertrand Moreau

The invention relates to a laser device comprising a number of fiber amplifiers () delivering a number of optical waves, which is supplied by an oscillator () that delivers a signal wave, characterized in that said device comprises:

Laser device comprising means for controlling the phase of a large number of coherent sources

The invention relates to a radial slaving method and to a reproduction device implementing it for optical discs. In an optical head of a conventional reproduction device using a four-quadrant detector with four photodiode is distributed on either side of a direction parallel to the axis of the track, the individual signals of the photodiodes (dto d) are combined in order to obtain read signals along the two diagonals (diag, diag) by subtraction (). A phase comparison signal circuit () makes it possible to construct a radial error signal (Sr) by measuring the phase shift of the diagonal read signals. The invention applies in particular to phase discs with slightly phase-shifting marks.

Radial control method for a device for reproducing information of an optical disk, and reproduction device for carrying out said method

The invention relates to a system for reading a magnetic medium having several tracks of data which can be read in parallel with a detection device having at least as many detectors as there are tracks, making it possible to read simultaneously and at regular intervals a sample of data on each track. This system furthermore includes a processing circuit configured to receive each sample of data to be processed from each track together with sample of a first adjacent track and sample of a second adjacent track and to calculate the cross-talk affecting the sample of data to be processed due to the adjacent tracks. An integration circuit configured to receive the cross-talk value calculated by the processing circuit, integrates these values at each read time, and at subsequent read times. The systems also include a relative track-following control circuit configured to receive the result of integration of the integrator circuit and to supply a track-following control signal for the detection device.

Tracking system for recording/reading a data medium and recording medium

A clock circuit for the reading of sequential information elements includes a phase-locked loop for the control of the controlled oscillator. In the case of a reading system with n tracks, the phase computation circuit, the digital filter and the controlled oscillator each include as many memories (delay circuits R 1.1, . . . R 2.1, . . . R 3.1, . . . ) as there are samples of information elements (or information tracks) to be processed almost simultaneously. The invention finds particular application in the reading of high-density recording media.

Clock circuit for the reading of sequentially recorded information

Process for reading information

A recording/reading head for multitrack information media including magnetic tape recorders comprises a matrix of elementary heads positioned in rows and columns. The columns, and especially the neighboring columns, are not parallel to one another.

Matrix type recording/reading head with zigzag structure

This magnetic head essentially has at least one excitation conductor located below two layers made of magnetic material constituting the magnetic poles of the head and separated by a gap. The positioning of the conductor is such that it forms an angle different from 0.degree. or 90.degree. with respect to the direction of the gap. Different embodiments of the invention are provided for, notably with several conductors to set up a matrix-type control. Application to write/read magnetic heads.

Magnetic write/read head having at least two conductors crossing a gap

System for serial reception or reading of information

A system for the reading of a multitrack recording medium comprising a device enabling the reading, on the width of each track, of a number n of information samples. The system includes a filter enabling the making of several combinations of several samples of a track, these combinations differing from one another by a shift equal to one or more samples; a sub-sampling circuit that chooses a determined combination from among the different combinations of a track under the control of a position predictor; a positional error computation circuit computing the positional error of the chosen combination and giving an error correction signal to the position predictor.

System for the reading of a multitrack recording medium for enabling the

System for recording/writing on a recording medium in which there are distributed, on the tracks, groups (G0) of tracks with positive continuous components and groups (G1) of tracks with negative continuous components. In reading, the values of the different signals are integrated for each track. Then, on the one hand, a first addition circuit S1 adds up the results of integration of the first tracks of each group of tracks and, secondly, a second addition circuit S2 adds up the results of integration of the last tracks of each group of tracks. A comparison circuit (CD) compares the results of additions of the two addition circuits to correct the track-following operation.

Information recording medium encoded to enable track following and

A reading head has odd and even elemental areas for reading corresponding odd and even information segments that alternate to make up a frame of information on a record medium. The odd elemental areas provide a train of sequential odd information segments, each odd segment having cross-talk associated with the neighboring even segments which are on either side thereof when it is read from the record medium. Similarly, the even elemental areas provide a train of even information segments, each even segment having cross-talk associated with the odd segments which neighbored it on either side when it is read from the record medium. To correct for such cross-talk in both signal trains, both are fed to each of two cross-talk correcting circuits. These circuits derive needed adjacent segment information as to the cross-talk producing adjacent segments from one of the trains being fed thereto so as to process the segments of the other train being fed thereto for cross-talk correction.

Reading device with cross-talk correction of two signal trains

Information recording medium encoded to enable track following

The magnetic recording head of the invention comprises an electrical conductor constituted by the poles themselves or by a magnetic shunt, which gets saturated when an electrical current is sent to it. It is thus possible to control the field at the gap and control the recording by this electrical current which acts by inhibition or validation of the writing, respectively.

Integrated recording magnetic head

Method and apparatus for preventing cross-talk during reproduction of

The invention relates to a method and system reading data recorded in the form of tracks on a magnetic recording medium. The recorded data is read by a row of read heads greater in number than a number of data tracks. The system of the invention does not require the read heads to follow the data tracks when reading recorded data, and allows a magnetic tape to be read even if the positions of the data tracks relative to the read head positions are unknown. The reading system of the present invention finds particular application in the area of reading high density recorded magnetic tapes.

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Bures sur Yvette, France

Joseph Colineau