| 摘要 |
In an HD-DVD, record densities are different between in a lead-in area and in a data area. On the other hand, in a DVD, the record densities of a lead-in area and a data area are equal. In discriminating an optical disc between the HD-DVD and the DVD, a light beam having a wavelength for the HD-DVD or for the DVD is projected onto the respective areas of the lead-in area and the data area, and a comparison is made between the amplitude of a tracking error (TE) signal obtained on the basis of reflected light from the lead-in area and that of a TE signal obtained on the basis of reflected light from the data area. When the difference between both the amplitudes is within a predetermined range, the optical disc is discriminated as the DVD, and when the difference between both the amplitudes is larger than the predetermined range, the optical disc is discriminated as the HD-DVD.
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