Patent ID: 6457128
Filing Date: 2002-09-24
Classification: G06K,G11B

Abstract:
An optical disk on which data is recorded comprising:a first recording area where main information is recorded, a second recording area having barcode-like marks each of which has a strip-like configuration in a radius direction, which are disposed in a circumferential direction and which are recorded as sub information wherein said first recording area contains a control data area which represents a physical property of the optical disk and is located in the lead-in area, said second recording area is disposed inside from said control data area on said first recording area and said second recording area is overlapped with said lead in area, wherein in a prescribed region of said control data area, an identifier is provided for indicating whether said barcode-like mark is present or not on said optical disk, said identifier and said barcode-like mark are in respectively different locations on said disk, said barcode-like mark disposed in a circumferential direction, and said barcode-like mark having a plurality of bars, each of said bars extending in a radial direction, and a mark is marked by laser beam on an information layer of said disk, information based on the position of said mark is encrypted and said encrypted information is included in said barcode-like mark, a specific ring-like area on the second recording area is divided into a plurality of sections with substantially the same width (&tgr;) in a circumferential direction, said width (&tgr;) being corresponding to a frequency of a channel clock of modulation signal of said sub information, said barcode-like marks are formed within the sections corresponding to the sub information, with RZ recording method, and a width of the barcode-like mark is substantially half or less of the section width (&tgr;).