Patent ID: 7027371

Claim:
An optical disc recording/retrieving apparatus comprising: a motor for rotating disc, which has a spiral groove with wobble whose carrier frequency is constant in space frequency and is meandered according to a signal modulated with a constant carrier frequency f L0 and address information and also has a recording layer, at a constant angular velocity with a center of the disc being an axis of rotation, the disc having address information identifying each recording data block, which is a unit of recording information located at a specified position in the spiral groove, and a synchronization pattern identifying a head position of the recording data block; an optical pick-up for generating a focused laser beam irradiating the disc for recording/retrieving; linear motor for moving said optical pick-up radially of the disc to a given address; a focus servo circuit for focusing the focused laser beam on the recording layer; groove tracking servo circuit for scanning the spiral groove by the focused laser beam; a detector and decoder circuit for detecting and decoding a carrier frequency f A0 , address information and block synchronization signal from the meandering groove geometry; a data-sequence generation circuit for generating a recording data sequence, which is modulated in terms of mark length modulation, in synchronism with a data reference clock T which has a frequency f d0 and with a start position of the recording block; a laser-power modulation circuit for modulating a recording laser power in accordance with the recording data sequence; a reference signal generator for generating a data reference clock T which varies in reverse proportion to a radius position when the focused laser beam is moved radially of the disc to a given address of a recording data block; and a data-sequence synchronization circuit for synchronizing a data sequence, which is to be written in the given recording block, with the start position of the recording block and also making a fine adjustment of r.p.m. (revolutions per minute) of the disc so as to satisfy a relation f d0 =N f A0 at any radius position, by comparing in phase between a reference signal f R0 , which is obtained by dividing the frequency f d0 at a particular radius by N (N is an integer), and the carrier frequency f A0 which is detected at the given address from the meandering groove geometry.