RAIL FRICTION CALIBRATION

摘要

An optical disc drive scans selected tracks on a record carrier via a beam of radiation ( 24 ) from a head ( 22 ). The head is positioned on the track by a tracking system. The tracking system includes a main servo loop, constituted by a motor ( 40 ) for moving the head along a rail ( 46 ) transverse to the tracks, position means ( 41 ) for generating a position signal in dependence of an actual position of the head, and an amplifier ( 44 ) generating a driving signal coupled to the motor. The amplifier has an adjustable gain that is set in dependence on a friction profile. The device has a memory ( 34 ) for storing the friction profile as determined during a calibration process. By compensating friction of the rail a reliable response of the tracking system to jump commands is achieved. Power dissipation is reduced because the driving signal as generated is just strong enough to move the head along the rail.