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. 27, 1991
Filed:
Mar. 08, 1990
Shuji Terasaki, Fukushima, JP;
Mitsuru Ohta, Fukushima, JP;
Akiyasu Ishii, Fukushima, JP;
Yuji Kojima, Kanagawa, JP;
Akira Tanaka, Kanagawa, JP;
Kureha Chemical Industry Co., Ltd., , JP;
Fujitsu Limited, , JP;
Abstract
An optical phase plate is provided in the form of a drawn and oriented film or sheet, having a composition comprising a vinylidene fluoride resin and a methyl methacrylate resin in a mixing ratio of the former to the latter between about 65/35 and about 85/15 by weight, in which the crystal structure of the vinylidene fluoride resin consists mainly of a .beta.-form and the film or the sheet has dimensional stability and a retardation value R within a range from 500 to 650 nm. The optical phase plate is produced by uniformly kneading and melt-extruding the predetermined PVDF/PMMA mixture into a sheet and subjecting the sheet to drawing and then to heat treatment.