| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical information recording medium wherein a focus searching process and a layer jumping process can reliably and promptly be performed even when appropriate sigmoid characteristics can not be obtained by deterioration or the like of a certain signal recording layer of a plurality of signal recording layers, to provide an optical reproducing device and to provide a focus controlling process of the optical reproducing device. <P>SOLUTION: An optical disk 10 is constituted by multi-layering a first signal recording layer 12a, a first resin film layer 13a, a second signal recording layer 12b, a second resin film layer 13b, a third signal recording layer 12c, a third resin film layer 13c, a fourth signal recording layer 12d and a protective resin film layer 140 in this order on a substrate 11. The optical disk 10 has a property that maximum voltages of voltage waveforms showing sigmoid characteristics of focus error signals in the signal recording layers 12a to 12d becomehigher successively from a laser beam irradiation surface side. <P>COPYRIGHT: (C)2004,JPO&NCIPI |
