Thomson-csf

Thales

Thomson Multimedia S.a.

Michel Audoin

Joseph Colineau

Claude Bricot

Jean-Louis Gerard

Pierre Berthet

Charaf Hanna

Christian Claudepierre

Jean L Gerard

Mario De Vito

Bertrand Moreau

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 device and system for the reading of a recording medium, which enables the reading of high-density information and the removal of disturbance (or cross-talk) from the information. The invention includes chiefly a reading device carrying out the parallel reading of the information from N pixels of an optical detector array and giving at least two sub-trains of samples in series (X, Y, Z), a cross-talk correction circuit for each sub-train of samples, each sub-train giving a train of cross-talk corrected samples (X', Y', Z'), and an input sequencer giving each correction circuit a train of samples to be corrected (Ys) from a first sub-frame of samples (Y) and samples (XN-1, Z0) from at least one second frame of samples (X,Z). This device and system can be applied to the reading of high-density recording media (magnetic or optical).

Device and system for reading recording media with cross-talk correction

System for serial reception or reading of information

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

A process and device for focussing a light energy beam on a data carrier comprising sites fromed of virgin areas free from any data recording provided along tracks and serving as reference plane for said focussing. In a preferred variation, these areas are preceded by flags associated with a specific code. Control is achieved by measuring the deviation between the plane of focussing of a beam into a spot scanning the tracks and the reference plane formed by the surface of the virgin areas. Between two passages of these areas of the measurements are stored. The focussing error signal is obtained by filtering these measurements.

Process and system for optical recording and reading on a mobile data

A process and device for focussing a light energy beam on a data carrier comprising sites formed of virgin areas free from any data recording provided along tracks and serving as reference plane for said focussing. In a preferred variation, these areas are preceded by flags associated with a specific code. Control is achieved by measuring the deviation between the plane of focussing of a beam into a spot scanning the tracks and the reference plane formed by the surface of the virgin areas. Between two passages of these areas the measurements are stored. The focussing error signal is obtained by filtering these measurements.

The invention relates to devices for optically transcribing in a track carried by a support medium data to be written in or read out. The invention provides a pre-engraved track follower device for a transcription device in which a loop for radial control of the reading spot scanning the track is provided with sampling means taking samples during scanning of nonpost-engraved parts of a pre-engraved track, said scanning corresponding to a data write or read phase. The invention applies more particularly for digital data transcription devices using a single spot for locating a pre-engraved track and since optically writing data therein.

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Villeneuve St Georges, France

Michel Audoin