Patent ID: 7170680

Claim:
A privacy screen for a display comprising: a) a rotating film for receiving vertically linearly polarized light from the display, rotating the light to about a 45 degree linearly polarized light upon transmission of the polarized light through the rotating film; b) a first uniaxially birefringent film for transmitting light received from the rotating film, the first birefringent film having a thickness d 1 and a retardation value R: R =( n e −n o ) d 1 /cos θ 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 c) a first polarizing film having a polarizing axis positioned to receive the light transmitted from the first birefringent film.