US Patent 7190518 Systems for and methods of three dimensional viewing

The present invention relates in general to systems for and methods of three-dimensional viewing of displays and projections. One embodiment two layers (50, 90) are uniform polarizing filters and a birefringent layer with individually switchable elements (60) is sandwiched between them. Together these layers (50, 60, 90) constitute a parallax layer (40). This parallax layer (40) is located at a certain distance from a display (10). This placement, and the existence of opaque areas on the parallax layer (40) which permits to a viewer see a three-dimensional image. The individual elements (601–615) of the birefringent layer (60) are controlled by a control element (80), which is in communication with a head-tracking sensor (85). This allows the individual elements (601–615) of the birefringent layer (60) to be selectively turned on and off according to the position of the viewer's head.