OPTICALLY READABLE RECORD CARRIER AND MAMUFACTURING APPARATUS AND RECORDING AND READING APPARATUS

摘要

A record carrier (1) comprises a disc-shaped carrier provided with a radiation-sensitive layer (6) and is formed with a servo track (4). The servo track exhibits a track modulation in the form of a radial wobble whose frequency is modulated with a position-information signal (Fig. 2). Also revealed is an apparatus (Fig. 8) for forming the track pattern during manufacture of the record carrier (1). When an information signal (Vi) is recorded on the record carrier (1) and the recorded signal is read by means of a recording and/or read apparatus (Fig. 4) the position-information signal (Fig. 2) is recovered by means of an FM demodulator device (60) from variations in the scanning beam (55) which are produced by the track modulation. Moreover, a clock signal for the purpose of scanning-velocity control is recovered from said variation in the scanning beam. Furthermore, embodiments of the record carrier which are very suitable for recording EFM-modulated signals are described.