Record carrier and tracking signal generator circuit.

摘要

A record carrier for a data storage apparatus has an information layer (19) having tracks (11, 13) for storage of data, the tracks being so arranged and disposed to form a diffraction grating for an incident radiation beam so as to generate a push-pull signal usable as an uncorrected track following signal. The tracks are comprised of longitudinally disposed sectors, each sector having an associated header (24, 44) and associated servo areas. The storage apparatus, in operation, may produce and read detectable modulations in the record carrier by means of directing incident radiation beam to a spot (70) in the information layer (19). The spot is moveable along the longitudinal direction of one of the tracks and perpendicularly across substantially parallel tracks. The storage apparatus, in operation, reads the detectable modulations in a returned radiation beam. The record carrier has a track format in each track comprising discontinuities (41) for generating a correcting signal for correcting said push-pull signal, located in each servo area, qualifier modulations (26, 46) for producing a qualifier signal in the servo area (40) for confirming the coincidence of one of the sector headers under the spot and modulation clocking (21) comprising nonreflective timing pits.