Patent ID: 8216656
Filing Date: 2012-07-10
Classification: G11B,Y10T

Abstract:
1. An optical disc manufactured by the steps of manufacturing a stamper using a disc master having a recessed portion formed therein, the stamper having a projecting portion formed by transferring the recessed portion; manufacturing a disc substrate using the stamper, the disc substrate having a recessed portion formed by transferring the projecting portion in the stamper; and forming a predetermined layered structure on the disc substrate, the optical disc comprising: a boundary portion between the recessed portion and a non-recessed portion formed in the disc substrate that includes a small protrusion which protrudes from a flat surface of the non-recessed portion, wherein a height of the small protrusion from the flat surface of the non-recessed portion is in the range of 3% to 10% of a height of the flat surface of the non-recessed portion from the recessed portion, and a radius of curvature of the small protrusion is in the range of 20% to 60% of the height of the flat surface of the non-recessed portion from the recessed portion.