Driving signal for coarse servo employing sampled offset signal

摘要

An apparatus and method are provided for generating a coarse actuator drive signal. A fine actuator, operatively attached to a coarse actuator, defines an optical pathway through which light reflected from various structures residing on a disk passes. A split detector, attached to the coarse assembly and positioned to intercept light from the optical pathway, receives the light reflected by the structures residing on the disk and generates signals representative of the light incident on each half of the split detector. A difference between the signals produced by the split detector indicates that the coarse actuator is not centered or aligned with respect to the fine actuator. Processing circuitry processes the signals produced by the split detector according to the disk structure utilized to produce the signals and generates a coarse actuator drive signal. The drive signal is applied to the coarse actuator thereby causing the coarse assembly to move and ultimately centering or aligning the fine assembly relative to the coarse assembly.