Patent ID: 6351438
Filing Date: 2002-02-26
Classification: G11B

Abstract:
An apparatus for reading and/or writing information from/onto an optical data carrier (1), which apparatus comprises a transducer (5) for optically reading a signal (x) recorded on the data carrier and in response thereto supplying a detection signal (S0), and means for rotating the data carrier (1) and for translating the transducer (5), which apparatus further comprises correction means (16, 17, 18) for the reduction of errors in the detection signal (S0) as a result of radial tilt of the transducer (5) with respect to the data carrier (1) and further comprises error signal generating means (20) for generating an error signal (Se) for the correction means (16, 17, 18), characterized in that the error signal generating means (20) calculate the error signal (Se) from correlations between a first auxiliary signal (S1) and a second auxiliary signal (S2) and from correlations between the first auxiliary signal (S1) and a third auxiliary signal (S3), the second auxiliary signal (S2) and the third auxiliary signal (S3) being estimates of the signal (x) recorded on the data carrier (1), the first, the second, and the third auxiliary signal being derived from the detection signal (S0), the first auxiliary signal (S1) having a first delay (T) with respect to the second auxiliary signal (S2), which first delay has a magnitude corresponding to the duration of one revolution of the data carrier, the third auxiliary signal (S3) having a second delay (2T) with respect to the second auxiliary signal (S2), which second delay (2T) has a magnitude corresponding to the duration of two revolutions of the data carrier (1).