Patent ID: 6314079
Filing Date: 2001-11-06
Classification: B29C,B29D,B29L,B32B,G11B

Abstract:
An optical disc comprising:a first disc warped in a first direction when viewed in cross section and having a first information recording portion on a first surface of a first substrate, said first disc being warped in said first direction by controlling a temperature difference between a mold used to form said first surface of said first substrate and a mold used to form an opposite surface of said first substrate; anda second disc warped in a second direction opposite to the first direction when viewed in cross section, said second disc having a second information recording portion on a first surface of a second substrate, said second disc being warped in said second direction by controlling a temperature difference between a mold used to form said first surface of said second substrate and a mold used to form an opposite surface of said second substrate;wherein,said first disc is laminated to said second disc such that said first and second information recording portions do not face each other, andsaid optical disc is configured such that during reproduction of information signals in the information recording portions, a laser light beam is incident on a surface of the first substrate not carrying the first information recording portion, and the information signals in the first disc or the second disc are selectively reproduced by varying a focal point position of the laser light beam.