Quasi-constant linear-velocity disk having corresponding radii of adjacent annular zones related by a rational number for distributing prerecorded indicia to form a coherent write clock signal

Claim 1

In a disk adapted for recording and playing back information-bearing binary bits at a fixed rate from information-storing tracks grouped radially into a plurality of N, greater than two, progressively wider annular zones encircling the center of said disk, the improvement wherein: (a) the ratio of the radius of any given outlying zone to the corresponding radius of the adjacent inner zone being a fixed rational number n/d, greater than one, for each adjacent pair of zones wherein n and d are fixed integers; and (b) each track revolution within a given zone, i, has a fixed integer number, P i , of equally spaced radially aligned uniquely identifiable indicia calculated from: P.sub.i =jx(n/d).sup.i-1 ×(d).sup.N-1 where j is any positive integer and i is 1 for the innermost zone and is N for the outermost zone whereby P.sub.i+1 /P.sub.i =n/d, so that when said disk is rotated at a constant angular velocity to cause the indicia to sweep past a fixed radially extending reference, a constant phase relationship is maintained at the reference between adjacent indicia in the same track and between the last indicium on any given track in a particular zone and the next indicium on any other track in the same zone.