Injection compression molding method of a spectacle lens and a s

Details Injection compression molding method of a spectacle lens and a s Injection compression molding method of a spectacle lens and a s

1996-12-03

1999-10-26

Vargot, Mathieu D.

Plastic and nonmetallic article shaping or treating: processes

Optical article shaping or treating

Changing mold size or shape during molding or with shrinkage...

2643287, 425808, B29D 1100

Patent

active

059722525

ABSTRACT:
In an injection compression molding method of a lens, in which a mold is closed to preserve a predetermined compressing margin in a cavity 3 for a lens, molten resin is injected and fed into the cavity 3 for the lens, and compressed for the aforementioned predetermined compressing margin before or after the injection and the feed of the molten resin is completed, the predetermined compressing margin (the degree of slightly opening S.sub.(-)) for producing a minus lens is molded is defined to be larger than the predetermined compressing margin (the degree of slightly opening S.sub.(+)) for producing a plus lens is molded. As a result, even when the minus lens is molded, the larger area of the cavity can be ensure and a flow property of the molten resin in the cavity is improved, so that the molten resin reached the inside of the cavity 3 flow through the central portion of the cavity 3 into the peripheral portion, with the result that the appearance of a weld mark in the central portion is avoided.

REFERENCES:
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patent: 4364878 (1982-12-01), Laliberte et al.
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patent: 4900242 (1990-02-01), Maus et al.
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Patent Abstracts of Japan; vol. 18, No. 524 JP 06-182833, Jul. 5, 1994 (5 pages).
George Galic's letter to German Patent Agent dated Nov. 10, 1997 (2 pages); including an Affidavit to the European Patent Office dated Nov. 7, 1997 (7 pages).
SPIE-The International Society for Optical Engineering Reprinted from Ophthalmic Lens Design and Fabrication vol. 1529--Dated Jul. 25-26, 1991 (pp. 13-21) Improved Plastic Molding Technology for Ophthalmic Lens & Contact Lens by George Galic and Steve Maus.
Optical World; Injection-compression moulding of Rx polycarbonate lenses by George Galic (4 pages).
Engel Information; Sandwich Press Injection (10 pages).

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