Patent ID: 8208358

Claim:
An optical disk device configured to radiate laser light onto an information recording medium having information tracks, in order to reproduce, by use of reflected light therefrom, information recorded on the information recording medium, the optical disk device comprising: an adaptive equalizer circuit configured to equalize a reproduced signal obtained from the reflected light to a predetermined target equalization characteristic; a binarizer circuit configured to generate a binary signal using a waveform output from the adaptive equalizer circuit; and a reproduced signal quality evaluation circuit configured to conduct a reproduced signal quality evaluation in order to evaluate a quality of a reproduced signal, by using the waveform output from the adaptive equalizer circuit; an equalization characteristic correction circuit configured to correct an equalization characteristic of the adaptive equalizer circuit, such that the equalization characteristic of the adaptive equalizer circuit has a fixed group delay; and an equalization characteristic control changeover switch configured to conduct a changeover of the adaptive equalizer circuit, between use and non-use of the correcting operation by the equalization characteristic correction circuit; wherein the optical disk device is configured to conduct the changeover of the equalization characteristic control changeover switch such that: the equalization characteristic correction circuit is not used when information reproduction is conducted by inputting the reproduced signal obtained from the information recording medium to the binarizer circuit; and the equalization characteristic correction circuit is used when quality of a reproduced signal obtained from an information recording medium is evaluated by using the reproduced signal quality evaluation circuit.