Title:
【発明の名称】光ディスクの製造方法
Document Type and Number:
Japanese Patent JP3032587
Kind Code:
B2
Abstract:
Resin, typically polycarbonate is injection molded into a disc substrate under select conditions, for example, at a mold temperature of 100-160 DEG C., an injection velocity of 100-120 g/sec., and a pressure of 10-60 kg/cm2, such that the birefringence of a radially inner portion of the substrate is higher by about 15-50 nm than the remaining substrate. A center hole is perforated in the substrate and a hub is attached to the substrate around the center hole. At the end of hub attachment, the substrate has a uniform distribution of birefringence over the entire area. Any increase of DC modulation is thus avoided.
Inventors:
Tsuneo Kuwahara
Noriyasu Akashio
Noriyasu Akashio
Application Number:
JP41874390A
Publication Date:
April 17, 2000
Filing Date:
December 28, 1990
Export Citation:
Assignee:
TDK Co., Ltd.
International Classes:
B29C45/14; B29C45/26; B29C45/76; B29D17/00; G11B7/26; G11B11/10; G11B11/105; B29L17/00; (IPC1-7): B29C45/26; B29C45/76; G11B7/26
Domestic Patent References:
| JP1291914A | ||||
| JP2253909A | ||||
| JP1160620A | ||||
| JP1222918A |
Attorney, Agent or Firm:
Youichi Ishii