Patent ID: 7636287

Claim:
A reproduced signal equalizing method for optical information media in which reproduced signals obtained by irradiating laser light to an optical information medium are equalized so as to bring a waveform corresponding to the reproduced signals close to a waveform having predetermined characteristics, the method comprising the steps of: sampling the reproduced signals in a predetermined cycle; inputting the reproduced signals sampled in the predetermined cycle to a Viterbi decoder, wherein the reproduced signals sampled in the predetermined cycle are unequalized; demodulating by the Viterbi decoder the unequalized reproduced signals sampled in the predetermined cycle to generate binarized data; defining a target waveform as a waveform based on the binarized data demodulated by the Viterbi decoder and a partial response waveform; calculating an equalization coefficient for producing a smallest difference between the target waveform and the unequalized reproduced signals sampled in the predetermined cycle by a least square technique using a matrix calculation; and equalizing the unequalized reproduced signals sampled in the predetermined cycle by using the calculated equalization coefficient.