Embedded servo patterning methods and apparatus

Abstract

The present invention involves a recordable disk having a first plurality of Sservo sample wedges in a first servo zone at an outermost position on the disk, a second plurality of Sservo sample wedges in a second servo zone which is radially adjacent the first servo zone, and a third plurality of Sservo sample wedges in a third servo zone which is radially adjacent the second servo zone. The Sservo sample wedges of the first plurality are equally spaced apart circumferentially around the disk by a first angle θ, the Sservo sample wedges of the second plurality are equally spaced apart circumferentially around the disk by a second angle θ=θ*N, and the Sservo sample wedges of the third plurality are equally spaced apart circumferentially around the disk by a third angle θ=θ*N. Advantageously, S=S/Nand S=S/N, the Sservo sample wedges of the second plurality are in radial alignment with every Nth wedge of the Sservo sample wedges of the first plurality, and the Sservo sample wedges of the third plurality are in radial alignment with every Nth wedge of the Sservo sample wedges of the second plurality. The number of servo samples are increased nearer the outer position of the disk for improved track following without increasing the number of servo samples at the inner position, which would undesirably decrease storage capacity, and no significant changes to servo detection hardware and software are required.