DELAY CLOCK TRACK READ BACK DATA TO COMPENSATE TIME VARIANCE DUE TO DISK THERMAL EXPANSION IN SPIRAL SERVO TRACK WRITING

摘要

Delay clock track read back data to compensate time variance due to disk thermal expansion in spiral servo track writing are provided to compensate the movement of indexes due to the thermal expansion of a disc, thereby improving the precision of spiral servo tracks used to record radial servo patterns. A clock head reads a clock track of a disc. A circumference index detector(106) is coupled to the clock head. A radial index detector(104) is coupled to the head of a hard disc drive. A phase detector(102) is coupled to the circumference index detector and the radial index detector. A delay line circuit(108) is coupled to the phase detector, the clock head, and the circumference index detector. A controller is coupled to the radial index detector and the circumference index detector.