DEVICE FOR SCANNING A ROTATING INFORMATION CARRIER

摘要

A device according to the invention for scanning a rotating information carrier (2) comprises a transducer (10) and control means (20, 22) for controlling a scanning parameter of the transducer (10), such as the radial position and the setting of a focus. The control means comprise difference signal generating means (20) for generating a difference signal (RE) which is indicative of a difference between a current value and a desired value of the scanning parameter, and correction signal generating means (22) for generating a correction signal (SC) in response to the difference signal. The correction signal generating means (22) comprise a delay loop having first in first out memory means for generating a delayed signal and feedback filter means for filtering the delayed signal. The device comprises rotation speed detecting means (8) for generating a clock signal (CL) having a frequency which is indicative of the rotation speed of the information carrier (2), the delay in the memory means being proportional to a period of the clock signal.