Pit spacing in the servo field of an optical disk for speed and direction detection and data retrieval

摘要

A sampled servo type optical disc and its driving apparatus is disclosed, in which by cyclically repeating wobbled pits or address pits of the optical disc composed by two significant digits at every N tracks, and preformatting by patterns spaced in different intervals at every track, when the optical disc driving apparatus seeks an object track, the seek direction of the optical head can be detected by the sequence of change of the pattern, and its seek speed can be detected at high speed by the detected result of the pattern, ensuring the speed control of the optical head in response to the detected seek direction and speed.