Patent ID: 7907489

Claim:
An optical-disc discrimination method for discriminating: a first optical disc which includes a record layer for recording data therein, and a protective layer for protecting the record layer, and in which the record layer has at least a first area and a second area that are formed at equal record densities; and a second optical disc which includes the record layer and the protective layer, and in which the record layer has at least a first area and a second area that are formed at different record densities; comprising the steps of: projecting a light beam which has a wavelength for the first optical disc or for the second optical disc, onto respective areas of the first area and the second area, and detecting respective reflected lights which are reflected from the first area and the second area on the basis of the projections of the light beam, by a photodetection portion; executing predetermined processing for electric signals which are outputted from the photodetection portion; and discriminating whether an optical disc is the first optical disc or the second optical disc, on the basis of a result of the predetermined processing for the reflected light from the first area, and a result of the predetermined processing for the reflected light from the second area, wherein: thicknesses of the protective layers of the first optical disc and the second optical disc are equal; the first areas are data areas in which data are recorded, and the second areas are lead-in areas in which management information items for managing the data areas are recorded; a record density of the first area of the second optical disc is higher than a record density of the second area of the second optical disc, and the record density of the second area of the second optical disc is substantially equal to record densities of the first and second areas of the first optical disc; the light beam which is projected onto the first area and the second area is a light beam of a wavelength for use in reproduction of the first optical disc; and the predetermined processing is a process of obtaining an error rate and making a judgment on whether or not read of information is possible.