Patent ID: 6239853
Filing Date: 2001-05-29
Classification: G02F

Abstract:
An assembly for reducing the viewing angle of light emanating from display comprising:an input polarizer film and an analyzer polarizer film, said films being spaced apart and parallel, the analyzer polarizer film having a transmission axis oriented so that it transmits linear polarized light incident thereon which is 90.degree. to the linear polarized light exiting through the input polarizer,a half-waveplate assembly positioned between the input polarizer film and the analyzer polarizer film, said assembly causing linearly polarized light propagating orthogonal to the surface of the display to be transmitted through the waveplate assembly rotated 90.degree.,wherein the half-waveplate assembly comprises a first waveplate and at least one second waveplate, the at least one second waveplate spaced a fixed distance from the first waveplate, each waveplate having multiple alternating birefringent and isotropic stripes, the isotropic stripes transmitting polarized light normally incident thereon without rotation and the birefringent stripes transmitting polarized light normally incident thereon with a defined angle of rotation, the second waveplate being positioned so that the normally incident polarized light passing through the isotropic stripes on the first waveplate will pass through one of the birefringent stripes on the second waveplate and normally incident polarized light passing through the birefringent stripes on the first waveplate will pass through one of the isotropic stripes on the second waveplate causing the polarized light normally incident on the first waveplate to be transmitted from the second waveplate rotated 90.degree..