Patent ID: 7911914
Filing Date: 2011-03-22
Classification: G11B

Abstract:
1. An optical storage medium, comprising stacked data storage layers each of which is readable/writeable separately from the other layers by means of a light beam striking one side of the optical storage medium, wherein a recordable area of a first data storage layer including at least one recordable extended area portion is provided above a second data storage layer in a direction in which the first and second data storage layers are stacked, said at least one recordable extended area portion extends in a radial direction of said optical storage medium past an entire recordable area of the second data storage layer, and the second data storage layer includes a preformed read-only area representative of data which area is arranged so as to at least overlap said at least recordable extended area portion in the radial direction of said optical storage medium, and further wherein said second data storage layer is located furthest from a light-striking surface of said optical storage medium, and said first data storage layer is located next to said second data storage layer, closer to said light-striking surface.