Patent ID: 6147946
Filing Date: 2000-11-14
Classification: G11B

Abstract:
An optical disk apparatus for reproducing information recorded on an information face of a disk set in said optical disk apparatus by irradiating the information face with a laser beam, said optical disk apparatus comprising:focal point moving means for moving a focal point of the laser beam, for reproducing the information, in a direction perpendicular to the information face;reflected light detecting means for detecting a reflected light from the disk; anddiscriminating means for discriminating whether the disk set in said optical disk apparatus is a disk having a thick substrate or a disk having a thin substrate;wherein a maximum value AS1L.sub.max of an output signal from said reflected light detecting means and a maximum value ENV.sub.max of an amplitude of an information reproducing signal are detected while said focal point moving means is driven so that the focal point passes through the information face; andwherein said discriminating means discriminates whether the disk set in said optical disk apparatus is the disk having a thick substrate or the disk having a thin substrate on the basis of a ratio of ENV.sub.max and ASIL.sub.max.