Abstract: Optical system designs for projectors using flat light sources are disclosed. These projectors make use of imagers that manipulate the transmission or reflectance of light through electronically controlled pixels. The optical systems of the invention employ a rectangular flat light source that is matched to the aspect ratio of the imager itself, thus enabling very efficient use of light. Several flat light sources are possible for this projection system, including flat fluorescent lights and field emission light sources. Collimation of these light sources is an option. Polarization conversion means is also disclosed for such flat light sources, so that the light output is almost totally linearly polarized. Such projection systems can be very compact.

Abstract: Disclosed here is an efficient flat light source based on UV light excited photoluminescence of phosphors. An electrical discharge is confined to be substantially planar by a glass enclosure. This electrical discharge produces ultraviolet photons. These UV photons in turn excite phosphors to produce visible light with great efficiency and high intensity. In this invention, light is taken out of the light source from one side only. A UV light recycling means is also provided. Means for collimation of this light source is disclosed for projection display applications. Polarization conversion means is also described for such flat light sources, so that the light output is almost totally linearly polarized.