Abstract: Method and device for generating a control voltage for a position actuator of a disk drive system for displacing a lens of a pick-up unit to a given X-position. The actuator is operated by an open loop control system. First, parameters of the control system are calibrated so that the control system produces a control voltage (Va) from an input position signal (Xact_setp). Then, the control voltage is processed in a feed forward system for generating a processed control signal (Va_p) which is fed to the position actuator for displacing said lens to the X-position. A Z-value corresponding to the axial distance of the lens from a calibrated axial position and a temperature of the pick-up unit are measured. The position actuator operates according to the formula: Xdc=Va—p*K(Temp,Z)/(R(Temp)*C(Temp,Z)).

Abstract: Method and device for generating a control voltage for a position actuator of a disk drive system for displacing a lens of a pick-up unit to a given X-position. The actuator is operated by an open loop control system. First, parameters of the control system are calibrated so that the control system produces a control voltage (Va) from an input position signal (Xact_setp). Then, the control voltage is processed in a feed forward system for generating a processed control signal (Va_p) which is fed to the position actuator for displacing said lens to the X-position. A Z-value corresponding to the axial distance of the lens from a calibrated axial position and a temperature of the pick-up unit are measured. The position actuator operates according to the formula: Xdc=Va—p*K(Temp,Z)/(R(Temp)*C(Temp,Z)).

Abstract: Method and device for generating a control voltage for a position actuator of a disk drive system for displacing a lens of a pick-up unit to a given X-position. The actuator is operated by an open loop control system. First, parameters of the control system are calibrated so that the control system produces a control voltage (Va) from an input position signal (Xact setp). Then, the control voltage is processed in a feed forward system for generating a processed control signal (Va_p) which is fed to the position actuator for displacing said lens to the X-position. A Z-value corresponding to the axial distance of the lens from a calibrated axial position and a temperature of the pick-up unit are measured. The position actuator operates according to the formula: Xdc=Va_p*K(Temp,Z)/(R(Temp)*C(Temp,Z)) in which: Xdc=position signal for said given position Va_p=Va processed K=property of ‘actuator’ 21: Newton/Ampere R=resistance of ‘actuator’ coil C=Spring constant in Newton/meter.

Abstract: Method and device for generating a control voltage for a position actuator of a disk drive system for displacing a lens of a pick-up unit to a given X-position. The actuator is operated by an open loop control system. First, parameters of the control system are calibrated so that the control system produces a control voltage (Va) from an input position signal (Xact setp). Then, the control voltage is processed in a feed forward system for generating a processed control signal (Va_p) which is fed to the position actuator for displacing said lens to the X-position. A Z-value corresponding to the axial distance of the lens from a calibrated axial position and a temperature of the pick-up unit are measured. The position actuator operates according to the formula: Xdc=Va_p*K(Temp,Z)/(R(Temp)* C(Temp,Z)) in which: Xdc=position signal for said given position Va_p=Va processed K=property of ‘actuator’ 21: Newton/Ampere R=resistance of ‘actuator’ coil C=Spring constant in Newton/meter.

Abstract: Disclosed is an apparatus for reading and/or writing information from/to an information carrier (1), comprising a motor (2) for rotating the information carrier (1); pick-up unit (3) for directing a radiation beam (8) on the information carrier (1 ); traverse means having a permanent magnet stepping motor (6) for moving said pick-up unit from one read/write position on the information carrier to another read/write position; stepping motor driving means (7) for supplying said stepping motor with driving currents for coils in the stepping motor which generate magnetic fields, wherein the stepping motor driving means (7) has an open loop driving mode at which the read/write positions correspond to rest positions of the stepping motor (6) at which the magnetic fields generated by at least two coils (23, 34) in the stepping motor counteract each other.