Patent ID: 6480447
Filing Date: 2002-11-12
Classification: G11B

Abstract:
A method of reproducing information by scanning information marks recorded on tracks inside a predetermined information recording region by an optical spot, detecting an optical change of said information marks by said scanning operation, applying a signal processing to a reproducing signal obtained by said detection operation so as to reduce inter-symbol interference of an interference amount varying from said information mark to said information mark, and reproducing the information corresponding to said information mark, comprising the steps of:a) detecting the size of the optical change resulting from said information mark; b) calculating a plurality of equalization coefficients used for an equalization processing for the size of said optical change detected for each of said information marks; and c) reducing said inter-symbol interference on the basis of said equalization coefficients; wherein said equalization coefficient used for said equalization processing of the size of said optical change by a first information mark to reduce said inter-symbol interference in said step c) is greater than said equalization coefficient used for said equalization processing of the size of said optical change by a second information mark longer than said first information mark; wherein the detection of the size of said optical change in said step a) is the generation of an absolute value |X| of the reproducing signal; and wherein the detection of the size of said optical change in said step a) is the generation of an absolute value |Xâˆ’X0| of the reproducing signal, and X0 is an asymmetry which is a mean DC level of the highest density reproducing signal (3Tw).