The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 09, 1983
Filed:
Nov. 03, 1981
John R Holmes, Garden Grove, CA (US);
Discovision Associates, Costa Mesa, CA (US);
Abstract
A video disc member is described having a uniform value of birefringence over the entire information storage surface of the disc. This value of birefringence is the same at the inner information storage radius as at the outer information storage radius. The preferable composition of the video disc is a specially prepared polymethylmethacrylate, referred to as PMMA. The method of molding the improved video disc member includes an extended drying time for said composition and increasing the melting temperature. The increase in melt temperature provides a low and uniform value of birefringence. The improved drying cycle eliminates splay marks, blisters and other surface imperfections as compared to manufacturer recommended drying times.