Optical data store with a date storage disk formatted for positioning

摘要

Arranged on the data storage disk (6), alternating in track direction, are data sectors (63) and servo sectors (62). The servo sectors are formed without track grooves and, for deriving track error signals (PES), contain next to one another in the track direction a first and a second pair of information fields (A, B and C, D) for one marking element (65) each. The marking elements (65) in the two pairs of fields are arranged radially offset by one track interval (TW) with respect to one another. In the first pair of information fields (A, B) the marking elements lie symmetrically with respect to the track centre, in the second pair of information fields (C, D) the marking elements are offset thereto by half a track interval, impressed on a level with the track centres. This servo pattern makes it possible to compose the position error signal from sectionally linear curves of the same slope in terms of the absolute amount and the operational sign, which increases the control stability in positioning operations. This is of advantage in particular in the case of optical data stores with random access. <IMAGE>