Title:
MANUFACTURE OF OPTICAL DISC AND OPTICAL DISC
Document Type and Number:
Japanese Patent JPH04226724
Kind Code:
A
Abstract:
PURPOSE: To prevent increase of DC modulation generated after a hub is mounted to an optical disc.
CONSTITUTION: Birefringence of the inner peripheral part of a base sheet 1 after molding is made about 15-50nm larger than those of other parts e.g. by bringing the mold temp. to 100-160°C or making the injection speed to be 100-120g/sec or making the dwelling pressure to be 10-60kg/cm2 when the base sheet 1 is injection-molded. DC modulation is prevented from increasing when a disc is produced, by using this base sheet 1 and thereafter a hub is mounted.
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Inventors:
KUWABARA TSUNEO
AKASHIO NORIYASU
AKASHIO NORIYASU
Application Number:
JP41874390A
Publication Date:
August 17, 1992
Filing Date:
December 28, 1990
Export Citation:
Assignee:
TDK CORP
International Classes:
B29C45/14; B29C45/26; B29C45/76; B29D17/00; G11B7/26; G11B11/10; G11B11/105; B29L17/00; (IPC1-7): B29C45/14; B29L17/00; G11B7/26; G11B11/10
Attorney, Agent or Firm:
Yoichi Ishii