compatible device for optical discs of different systems

摘要

In a video disc player capable of providing special effects, e.g. fast or still playback, from discs on which the signal may be in any one of a plurality of different formats, e.g. PAL, NTSC, SECAM, the format is automatically identified, and comparator 82, 83 reference values are selected in conformity with the signal format and the occurrence of a special effect command. Horizontal synchronizing signals, Fig 8c, or signals from the disc drive, indicative of incremental rotation of the disc are integrated, being reset by the vertical synchronizing signal, Fig. 8B; the resulting angular position signal, Fig 8D, is fed to comparators 82, 83 to generate track jump signals, Fig 8G, at accurately defined disc positions dependent on the video format. The format may be identified by counting horizontal sync pulses, by discriminating the position of inserted control data by the use of a PAL or NTSC window, or by detecting an appended signal. IMAGE