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:
Nov. 30, 1999
Filed:
May. 19, 1993
Keiichi Nito, Tokyo, JP;
Tohru Nagai, Tokyo, JP;
Tsutomu Noguchi, Kanagawa, JP;
Mayumi Miyashita, Kanagawa, JP;
Junetsu Seto, Kanagawa, JP;
Katsumi Kohno, Miyagi, JP;
Sony Corporation, Tokyo, JP;
Abstract
There is disclosed an optical information record medium having an optical information record layer on a transparent substrate, in which the transparent substrate is made of a resin material mainly consisting of a polycarbonate resin that contains no more than 4 wt % of low molecular weight fractions having a weight average measured with respect to a polystyrene molecular weight of no more than 3500, in order to avoid a double refraction of an optical information record medium resulting in an improved signal to noise ratio and having superior thermal-transformation resistance and impact resistance.