Masatsugu Tanji

Video And Audio Disk File System

A new disk format and a new recorder were developed, based on the still picture disk file system which was put on the market a few years ago, whereby a video disk system that permits concurrent continuous recording of video and audio signals has been developed. In order to achieve a prolonged. recording time, the disk track pitch was narrowed from the conventional 2.5 μm to 1.6 μm and a contrivance was also made circuit-wise to eliminate the resulting cross talk interference. Because of these innovations, 13.3 minutes (24,000 frames) of continuous recording is now realized on a disk 20 cm in diameter. For a continuous recording of sound signals, a continuous track is necessary. To solve this problem, a spiral track was developed in lieu of the conventional concentric track. To indicate addresses, this track is locally interrupted. Such interruptions would normally interfere with sound recording but such interferences could be prevented by selecting the optimum relation between, the length of interruptions and the sound carrier frequency.