Optical disc having a high-speed access capability and reading apparatus therefor

Claim 1

An optical disc, comprising: a plurality of optical readable tracks including servo areas each having recorded therein servo pits containing clock synchronization information periodically disposed in each track, and wherein said servo areas are sequentially shifted by an integral multiple of a periodic clock duration by clock pits generated from a clock synchronization signal.

Claim 8

An apparatus for reading an optical disc in which servo area each recording therein servo pits containing at least clock information are periodically disposed in each track of a plurality of tracks, said servo areas being sequentially shifted in the longitudinal direction of said track relative to those disposed on the radially inner adjacent track, including rotational driving means for rotating said optical disc at a constant angular sped, and optical head moving means for moving an optical head in the direction radially of said optical disc for detecting signals from said optical disc, said apparatus further comprising: gate means for detecting a servo signal from a detection signal outputted from said optical head moving in the radial direction of the rotating optical disc and detecting a clock pit signal from said detection signal by using a gate timing adjusted in accordance with a seek speed, clock generating means for generating a clock signal synchronized with the detected servo signal; a counter for counting said clock signals and detecting said seek speed from a duration of said clock pit signal; a control circuit for generating a speed control signal on the basis of the count value of said counter at the timing with which said servo signal is detected by said gate means; and wherein the speed of said optical head moving in the direction radially of said optical disc is controlled by said speed control signal.

Claim 9

An apparatus for reading an optical disc in which servo area each recording therein servo pits containing at least clock information are periodically disposed in each track of a plurality of tracks, said servo areas being sequentially shifted in the longitudinal direction of said track relative to those disposed on the radially inner adjacent track, including rotational driving means for rotating said optical disc at a constant angular sped, and optical head moving means for moving an optical head in the direction radially of said optical disc for detecting signals from said optical disc, said apparatus further comprising: gate means for detecting a servo signal from a detection signal outputted from said optical head moving in the radial direction of the rotating optical disc and detecting a clock pit signal from said detection signal by using a gate timing adjusted in accordance with a seek speed, clock generating means for generating a clock signal synchronized with the detected servo signal; a counter for counting said clock signals and detecting said seek speed from a duration of said clock pit signal; a control circuit for generating a speed control signal on the basis of the count value of said counter at the timing with which said servo signal is detected by said gate means; and wherein the speed of said optical head moving in the direction radially of said optical disc is controlled by said speed control signal.