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Abstract

An optical information recording and/or read system comprises an optically readable record carrier (1) and an optical read and/or recording apparatus (FIG. 2). The record carrier (1) is provided with substantially concentric tracks (2). The record carrier (1) is divided into sectors (4). In the tracks of each sector address information is recorded by means of prior recorded radially juxtaposed address information patterns (8). The read and/or recording apparatus (FIG. 2) comprises a driver (20, 21) for rotating the record carrier (1), scanner (23, 25) for scanning the tracks (3) with a radiation beam (2) for the purpose of recording and/or reading, a closed-loop tracking system (23, 26) for keeping the radiation beam (24) aimed at the track (6) to be scanned, and an angular-position-detection system (23, 26, 27) for determining the angular position of the record carrier (1). The recording and/or read apparatus determine eccentricity-error (23, 26, 27, 50) by deriving a correction signal (Vc) from the sector addresses read while the tracking system is inoperative which correction signal is related to the radial displacement of the point of incidence of the radiation beam (24) of the record carrier (1) as a result of an eccentric position of the center of rotation (22) and out-of-roundness of the information tracks. When the tracking system is operative the correction signal (Vc) is employed as a control signal for an open-loop control system to compensate for the radial error caused by eccentricity and out-of-roundness.

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First Claim