Data recording and/or reproducing method and apparatus

A method of reproducing data from a disc-like recording medium having first and second zones divided radially thereof, each of the first and second zones comprising a plurality of data blocks arranged in a predetermined order, the data blocks of the first and second zones having first and second signals recorded at first and second frequencies thereon, respectively, comprising the steps of:

• scanning the data blocks in the first zone with a head while moving the head radially over the medium, and reading out the recorded first signal;
• generating a clock signal of a first frequency from a clock generating circuit;
• reproducing data from the first signal read out by the head, on the basis of the clock signal of the first frequency generated by the clock generating circuit;
• detecting the head position of the last data block in the first zone, and obtaining a detection signal;
• changing the frequency of the clock signal generated by the clock generating circuit from the first frequency to a second frequency in response to the detection signal, wherein the change of the frequency of the clock signal in the clock generating circuit is completed before the head reaches a boundary between the first zone and the second zone;
• scanning the data blocks in the second zone and reading out the recorded second signal;
• and
• reproducing data from the second signal read out by the head, on the basis of the clock signal of the second frequency generated by the clock generating circuit.

An apparatus for recording and/or reproducing data on or from a disc-like recording medium having a plurality of zones divided radially thereof, different frequencies being set for the zones each comprising a plurality of data blocks arranged in a predetermined order, the data blocks in each of the zones having signals recorded at a set frequency thereon, said apparatus comprising:

• a head for scanning the data blocks while moving radially over the medium, and for writing signals thereon and/or reading out signals therefrom;
• a clock generating circuit for outputting a clock signal, said clock generating circuit comprising first and second clock generators each for generating a clock signal of variable frequency, and a selector for causing the clock signals generated from the first and second clock generators to be selectively outputted;
• a signal processing circuit for converting data into a signal to be written by said head and/or for reproducing data from the signal read out by said head, on the basis of the clock signal outputted from said clock generating circuit;
• and
• a control circuit for controlling clock generating said circuit such that one of said first and second clock generators generates the clock signal of a frequency set for a zone which is currently scanned by said head and the other of said first and second clock generators generates the clock signal of a frequency set for a zone which is subsequently scanned by said head, wherein said control circuit instructs said selector of said clock generating circuit to switch the clock signal when said head shifts from the data blocks in the zone currently being scanned thereby to the data blocks in another zone, so that the clock signals generated from said first and second clock generators are alternately outputted from said selector.