Patent ID: 6773781
Filing Date: 2004-08-10
Classification: G11B,Y10T

Abstract:
A multi-layer-information-recording medium having a plurality of recording layers layered on a spacer layer on one side and adapted to an information recording and reproducing apparatus capable of recording or reproducing information on a single-layer-information-recording medium having a single recording layer and a cover layer on one side as a change in reflectivity by irradiating a light beam through the cover layer onto the recording layer, said multi-layer-information-recording medium comprising:a deepest recording layer disposed deepest from a light incident side surface at an optical distance d1 satisfying an equation d1=nt wherein â€œnâ€  denotes a predetermined refractive index of the cover layer of the single-layer-information-recording medium compatible in terms of at least reproducing and recording with said multi-layer-information-recording medium and â€œtâ€  denotes a thickness of said cover layer; and at least one shallow recording layer disposed at an optical distance d2 satisfying an inequality d2