SERVO SYSTEM FOR DISK DRIVE

PURPOSE:To improve the tracking performance and to compensate a data disk defect by receiving a servo burst signal from the data disk by a sample-and-hold means so as to select a slope of a difference signal and generating a position signal from a slope selector means. CONSTITUTION:The sample-and-hold circuit 32 receives a sample of servo sector from a disk 12 intermittently and a glass scale 46 measures the movement of a head 16 to offer a speed signal. A fill-in position signal obtained by integrating the speed signal is added to a position signal from a servo sector receiving a sample finally to offer the position information to a position compensator 44 when the head 16 is between servo sectors. An on-detector circuit 38 and an attenuation circuit 52 attenuates the movement of the head 16 strongly when the head 16 is at on-track.