Patent ID: 7052746

Claim:
A privacy screen for a display having a polarizing axis comprising: a) a first uniaxially birefringent film for transmitting light received from the display that wherein the light is linearly polarized along the display polarizing axis, the first birefringent film having a thickness d 1 and a retardation value R: R =( n e −n o ) d 1 /cosθ θ being the angle of light incident upon the screen from the display, and n o and n e being the refractive indices, respectively, along the ordinary and extraordinary axes of the first birefringent film, wherein d 1 is greater than 25 micrometers so that R is responsive to changes in θ; and b) a first polarizing film having a polarizing axis positioned to receive the linear polarized light transmitted from the first birefringent film.