OPTICAL DISK TRACKING AND SEEKING SYSTEMS AND SPECIFIC TRACK FORMATS (WOBBLED PITS)

摘要

. This invention relates to the field of data recording by optical or radiation means and in particular to optical disk technology. It provides for media configurations which can be read by systems such as those described within. The combinations described can provide accurate track crossing count and a more accurate track following signal than previously available. The media employs substantially parallel tracks to act as a diffraction grating, creating a push-pull signal which varies in a sine-wave fashion as the radiation spot used for reading or writing information in the tracks moves substantially perpendicularly across a group of track lengths. This creates the track count. The same detector and electronics which produce the count signal from the radiation beam returned from the media may be used to keep the beam on the track centerline (i.e. for following). The push-pull signal is used to indicate the spot's deviation from the centerline of the track. The low frequency content of the push-pull signal is corrected by combining it with a signal from a blank area. Another method of correcting it is with information obtained from a data-type signal which is produced in response to offcentered wobbled spots.