Patent ID: 7940633
Filing Date: 2011-05-10
Classification: G11B

Abstract:
1. A recording medium comprising: a first recording layer which is irradiated with laser light to thereby record therein record information; and a second recording layer which is irradiated with the laser light through said first recording layer to thereby record therein the record information, wherein each of said first recording layer and said second recording layer comprises a buffer area to buffer a changing operation of the recording layer in which the record information is recorded, a length, in a radial direction of said recording medium, of the buffer area in said first recording layer is set to be equal to or greater than a predetermined value, the buffer area in said second recording layer overlaps, along a normal line of said recording medium, with the buffer area in said first recording layer, a length, in a radial direction of said recording medium, of the buffer area in said second recording layer is longer than a length, in a radial direction of said recording medium, of the buffer area in said first recording layer, an edge on an outer circumferential side of the buffer area in said second recording layer is disposed at a position obtained by shifting by a tolerance length, which indicates an acceptable range of a relative position shift between an address which is defined on the predetermined position in the first recording layer and an address which is related to the predetermined position in the second recording layer, from an area portion of said second recording layer corresponding to an edge on an outer circumferential side of the buffer area in said first recording layer, and an edge on an inner circumferential side of the buffer area in said second recording layer is disposed at a position obtained by shifting by the tolerance length from an area portion of said second recording layer corresponding to an edge on an inner circumferential side of the buffer area in said first recording layer.