Method and apparatus for compensating variation of read data in an optical data storage

Claim 1

In a method for recording and reproducing information by which recording domains are formed locally on a recording medium and signals representing a rise and a fall in a reproduced waveform obtained from said recording domains are used as data, the improvement comprising the steps of: recording first and second timing patterns indicating start of demodulation for a lead-edge and a tail-edge of said recording domains, respectively, at a position before said recording domains on the recording medium; generating respective first and second timing signals indicating start of demodulation for said lead-edge and tail-edge of said recording domains independently by detecting the rise and fall of reproduced waveforms of said first and second timing patterns; and correcting the time position of said signals representing a rise and a fall in a reproduced waveform of recording domains on the basis of said first and second timing signals to correct for shifts in the rising and falling edges of said recording domains.

Claim 5

A method for recording and reproducing information according to claim I, wherein said recording medium is irradiated with a focused laser beam and said recording domains are formed by heat energy of said laser beam, said reproduced waveform being obtained by using light reflected by said recording medium

Claim 6

An apparatus for recording and reproducing information comprising: a head for forming recording domains on a recording medium depending on information to be recorded and for obtaining a reproduced waveform from said recording medium, depending on said recording domains; lead-edge and tail-edge detection means coupled with said head for detecting the lead-edge and the tail-edge of said recording domains by using said reproduced waveform and for producing a signal indicating the lead-edge and a signal indicating the tail-edge; demodulation starting timing signal detection means, coupled to said lead-edge and tail-edge detection means, for detecting independently timing signal patterns for starting demodulation, which timing signal patterns are recorded for the lead-edge and the tail-edge of said recording domains together with said recording domains at a position before said recording domains, respectively, by using said signal indicating the lead-edge and said signal indicating the tail-edge, and for producing separate timing signals for starting demodulation for the lead-edge and the tail-edge of said recording domains based on said detected timing signal patterns; and correction means coupled both to said lead-edge and tail-edge detection means and to said demodulation starting timing signal detection means for detecting a time interval between said timing signals for starting demodulation and for correcting the time interval between said signal indicating the lead-edge and said signal indicating the tail-edge by using said detected time interval between said timing signals for starting demodulation.

Claim 7

An apparatus for recording and reproducing information comprising: a head for forming recording domains on a recording medium depending on information to be recorded and for obtaining a reproduced waveform from said recording medium, depending on said recording domains; lead-edge and tail-edge detection means coupled with said head for detecting the lead-edge and the tail-edge of said recording domains by using said reproduced waveform and for producing a signal indicating the lead-edge and a signal indicating the tail-edge; demodulation starting timing signal detection means, coupled to said lead-edge and tail-edge detection means, for detecting independently timing signal patterns for starting demodulation, which timing signal patterns are recorded for the lead-edge and the tail-edge of said recording domains together with said recording domains at a position before said recording domains, respectively, by using said signal indicating the lead-edge and said signal indicating the tail-edge, and for producing separate timing signals for starting demodulation for the lead-edge and the tail-edge of said recording domains based on said detected timing signal patterns; and correction means coupled both to said lead-edge and tail-edge detection means and to said demodulation starting timing signal detection means for detecting a time interval between said timing signals for starting demodulation and for correcting the time interval between said signal indicating the lead-edge and said signal indicating the tail-edge by using said detected time interval between said timing signals for starting demodulation.