Patent ID: 7570566
Filing Date: 2009-08-04
Classification: G11B

Abstract:
1. A single-sided triple layer optical disc comprising: a light transmission layer; a first recording layer and a second recording layer which are accessed with a first laser beam; and a third recording layer which is accessed with a second laser beam, these layers being arranged in that order in a direction in which the laser beams enter, wherein the first recording layer is positioned a minimum of 550 μm from a light incidence plane, the distance between the first recording layer and the third recording layer is a maximum of 72 μm, the distance between the second recording layer and the third recording layer is a minimum of 15 μm, the distance between the first recording layer and the second recording layer is about 31 to 40 μm, the reflectivities of the first recording layer and the second recording layer with respect to the first laser beam range from 18 to 27%, the ratio therebetween being about 1.1 or less, the reflectivity of the third recording layer with respect to the first laser beam is below about 6%, and the areal recording density of the third recording layer is three times or more as high as the areal recording density of the first recording layer and the second recording layer.