Optical disc and method for making

Details Optical disc and method for making Optical disc and method for making

1993-10-21

1996-07-16

Vargot, Mathieu D.

Plastic and nonmetallic article shaping or treating: processes

Optical article shaping or treating

Light polarizing article or holographic article

29406, 156 731, 264248, 2643281, 360135, 369282, 425810, B29D 1100, B29D 1700

Patent

active

055364560

ABSTRACT:
Resin, typically polycarbonate is injection molded into a disc substrate under select conditions, for example, at a mold temperature of 100-160.degree. C., an injection velocity of 100-120 g/sec., and a pressure of 10-60 kg/cm.sup.2, 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.

REFERENCES:
patent: 4503531 (1985-03-01), Kato
patent: 4785444 (1988-11-01), Nakane et al.
patent: 4812345 (1989-03-01), Imai et al.
patent: 4892692 (1990-01-01), Takada et al.
patent: 5006058 (1991-04-01), Maruyama et al.
patent: 5073313 (1991-12-01), Umemura et al.
patent: 5102608 (1992-04-01), Frencken et al.
patent: 5265086 (1993-11-01), Ota et al.

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