Optical recording medium track indexing system

DETAILED DESCRIPTION The present invention has been devised with a view toward substantially eliminating the above discussed problems and has for its primary object to provide an improved optical disc of a type having at least one index region for each track, characterized in that the length of each of the index regions is chosen to be smaller than one frame and information is adapted to be recorded on the index region in a multiple recording fashion.
According to the present invention, each of the index regions in the optical disc has a length smaller than one frame.
When information recorded on the optical disc is decoded, information of one frame on the optical disc is, after decoding, dispersed into two frames.
Therefore, if an error occurs in recording the information recorded on the index region in multiplex recording fashion, since length of the index region is within one frame, the number of frame errors after the decoding is usually within the two frames.
Also even if the index region extends over two frames on the optical disc, number of the frame errors after decoding will be within three frames.
In this way, since the number of frame errors per track increases as a result of the multiplex recording of information on the index region within three frames, reduction in reliability of the reproduced signal is slight and an increase in the number of frame errors does not hamper the capability of correcting with an error correction.