Patent ID: 7586625
Filing Date: 2009-09-08
Classification: G11B

Abstract:
1. A position verifying apparatus for verifying extent of a relative shift in a radial direction (i) between a first recording layer and a second recording layer or (ii) between a first track and a second track, in an information recording medium comprising at least: the first recording layer in which the first track to record therein information is formed, and the second recording layer in which the second track to record therein the information is formed, said position verifying apparatus comprising: a first recording device for recording the information into a first area of the first recording layer; a second recording device (iii) for recording a part of the information by laser light which has penetrated the first area and (iv) for recording another part of the information by laser light which does not penetrate the first area, into a second area of the second recording layer including at least a partial area which faces the first area; a reproducing device for reproducing the part of the information and the another part of the information, recorded in the second area; and a judging device for judging whether or not the relative shift is within tolerance, on the basis of a transit position at which reproduction quality transits from one to the other out of the reproduction quality indicated by the part of the information reproduced and the reproduction quality indicated by the another part of the information reproduced.