Patent attributes
A screen having a free-viewing mode and a restricted-viewing mode, comprising a backlight emitting light into an unrestricted angular range in the free-viewing mode, and into a restricted angular range in the restricted-viewing mode. A transmissive imager is in front of the backlight. Light sources are outside the display area of the imager, and a transparent plate-shaped light guide scattering particles distributed therein is in front of the imager. In the free-viewing mode, the light sources are off, so that light from the backlight passing the imager passes the light guide unaffected. In the restricted-viewing mode, the lights are on, so that light radiating into a restricted angular range and passing the imager is superimposed by light that is scattered into the viewing space due to irradiation of light from the light guide. Thereby, the visibility of an image on the imager is reduced outside the restricted angular range.
