US Patent 7619818 Elliptically polarizing plate and image display

Patent 7619818 was granted and assigned to Nitto Denko on November, 2009 by the United States Patent and Trademark Office.

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Is a

Patent

Patent attributes

Current Assignee

Nitto Denko

Patent Jurisdiction

United States Patent and Trademark Office

Patent Number

7619818

Date of Patent

November 17, 2009

Patent Application Number

11569538

Date Filed

April 5, 2005

Patent Primary Examiner

‌

Stephone B. Allen

Patent abstract

An elliptically polarizing plate including: a polarizer; and an optical film that includes a laminate of: a retardation film A that includes a cyclic polyolefin resin-containing thermoplastic polymer and has uniaxially-aligned positive refractive-index anisotropy characterized by nx>ny≈nz; and a retardation film B that is fixed to homeotropic alignment and has positive refractive-index anisotropy characterized by nz1>nx1≈ny1, wherein the optical film is laminated on one side of the polarizer in such a manner that a slow axis of the retardation film A is perpendicular to an absorption axis of the polarizer. The elliptically polarizing plate can suppress a reduction in contrast at wide viewing angles when applied to in-plane switching mode active matrix liquid crystal displays, and can be highly effective for improvements against color shift.