Patent ID: 7171608

Claim:
Data playback equipment for playing back data recorded on a disk medium, comprising: analog-to-digital conversion means for converting an analog signal obtained from the disk medium to a digital value; target holding means for holding an ideal value for a signal related to an output of the analog-to-digital conversion means as a target; error detection means for detecting an error between the signal related to the output of the analog-to-digital conversion means and an output of the target holding means and generating a signal representing the error as a parameter signal correlated with an error rate of played-back data; a filter receiving the output of the analog-to-digital conversion means, the filter having taps of which coefficients are variable; and error minimization means for updating the tap coefficients of the filter so that an error between an output of the filter and the output of the target holding means is minimized, wherein the quality of the analog signal is adjusted so that the parameter signal is minimized, to thereby optimize the margin of the error rate of played-back data.