Patent ID: 7782723
Filing Date: 2010-08-24
Classification: G11B

Abstract:
1. A method for operating an optical drive system capable of reproducing/recording information from/to an associated optical carrier ( 30 ), wherein a position error and a speed error of a focussed radiation spot ( 12 , 53 ) on the carrier has been generated due to a surface defect ( 52 ) on the carrier, said defect causing a corresponding unreliable error signal and an unreliable servo signal during a first time interval ([ 1 , 2 ]), said optical drive system comprising: a control system ( error detecting means ( servo means ( said method comprising the steps of: registering values of a control signal of said control system, said control signal being selected from a group comprising error signals (RE, FE) and servo signals (Eactuator), determining the occurrence of a defect on the associated optical carrier by surface defect detecting means (DEFO), generating a first compensation control signal on the basis of said registered values, in which said first compensation signal is capable of reducing the speed error of the focussed radiation spot, applying said first compensation control signal to said control system during a second time interval ( generating a second compensation control signal on the basis of said registered values and said first compensation signal, in which said second compensation signal is capable of reducing the position error of the focussed radiation spot, and applying said second compensation control signal to said control system during a third time interval (