Patent ID: 6744717
Filing Date: 2004-06-01
Classification: B82Y,G11B,Y10S,Y10T

Abstract:
An optical disk drive for performing recording and reproduction of an optical disk comprising a recording layer and a super-resolution film disposed on the light incident side with respect to the recording layer, the recording layer having a phase change material that performs reversible phase change between a crystalline phase and an amorphous phase, the super-resolution film having a property to cause change in transmittance by irradiation of light, the optical disk drive comprising:a light source configured to irradiate the optical disk with a reproduction beam; a detector configured to detect a reflected beam from the optical disk to generate a first reproduction signal train; an arithmetic circuit configured to generate a second reproduction signal train by correcting the first reproduction signal train, wherein the arithmetic circuit multiplies a bottom of the first reproduction signal train by a coefficient of 1/Io(1+Tr1Ã—Ra), multiplies a peak of the first reproduction signal train by a coefficient of 1/Io(1+Tr2Ã—Rc) and multiplies a point between the bottom and the peak of the first reproduction signal train by a coefficient of an arithmetical mean of 1/Io(1+Tr1Ã—Ra) and 1/Io(1+Tr2Ã—Rc), respectively, where Io denotes intensity of the reproduction beam from the light source, Ra is a reflectance of an amorphous portion of the recording layer, Rc is a reflectance of a crystalline portion of the recording layer, Rc being higher than Ra, Tr1 is a transmittance of a portion of the super-resolution film corresponding to the amorphous portion of the recording layer and Tr2 is a transmittance of a portion of the super-resolution film corresponding to the crystalline portion of the recording layer; and a reproduction circuit configured to reproduce information recorded in the optical disk from the second reproduction signal train.