Abstract: A flat panel liquid crystal display module (34) has its front face adjacent a rear projection screen (40) and is illuminated by a pre-polarized collimated light source (10,14,16,18,22,26). Collimation is provided by either a Fresnel lens or a projection lens having a long focal length. The characteristics of the projection screen (40) provide narrowed vertical viewing angle and a fiber optic face plate (38) between the liquid crystal module (34) and the screen (40) provides sunlight rejection. The arrangement has greatly improved display brightness, with only minimal changes in contrast and color as viewing angle changes.

Abstract: A projection system having a rear projection screen (28) employs a collimating lens (26) in the form of a Fresnel lens adjacent the rear surface of the screen (28) to improve the image luminance at various viewing angles and provide uniform brightness over the area of the screen. A fiber optic face plate (30) or two crossed films of microlouver light control material is interposed between the collimating Fresnel lens (26) and the rear of the projection screen (28) to provide a high degree of blocking of high intensity light, such as sunlight, that may impinge upon the front of the screen. The optical fibers (42) of the fiber optic face plate have a low numerical aperture and an opaque cladding. The arrangement allows an image to be provided on the screen with high contrast even in the presence of sunlight striking the screen.

Abstract: A display screen of a projection system embodying a cathode ray tube, liquid crystal light valve, laser or the like is formed of a plastic sheet (22, 22a) that has embedded therein a number of microsphere diffuser particles (24, 24a) initially having a spherical shape and distributed in a uniformly isotropic density. The plastic sheet and its embedded particles are heated and stretched in a single direction and allowed to cool in their elongated form so that the diffuser particles (24a) then have an elongated elliptical shape and a density that is greater along one axis than it is along an orthogonal axis. The particle elongation and decreased density in the direction of stretch cause the diffusing sheet to have a diffusion cone angle (44), as measured in a plane containing the axis of stretch, that is significantly decreased, but with increased screen gain, whereas the diffusion angle (42) in the orthogonal unstretched direction remains relatively large, and also has an increased screen gain.

Abstract: Liquid crystal light valve projection systems can use substantially all of the reading light from a high intensity reading light source by converting all single polarization state. Light reflected from a polarization beam splitter (44) that cannot be used because it is of wrong polarization state is recovered with improved efficiency, color balance and collimation by means of a polarization recovery prism (50) employing a reflective surface (56) interposed between two quarter-wave retarders (58,60). The light of wrong polarization from the polarizing beam splitter (44) is passed through a first quarter-wave retarder (58), which circularly polarizes the beam. The beam is then reflected from a mirrored surface (56) to reverse the direction of the circular polarization.

Abstract: A flat panel visual display system having orthogonally disposed display electrodes which are provided by display command signals from a computer to cause activation of portions of the display is provided with additional electrodes. The additional electrodes are orthogonally disposed in a plane parallel to the display electrodes and are interconnected so that an operator touching the additional electrodes will shunt at least a portion of the display command signals to ground or back to the computer. The computer is provided with sensor circuitry for sensing the shunting and providing an indication of the location of the simultaneous occurrence of the display command signals and the operator's touch.

Abstract: A touch-sensitive overlay (20) for cooperative, optically proximate engagement with a visual display (22) of luminous character information (38) latently occupying one or more of a plurality of character locations (26) defined with a position-multiplexed coordinate array one from another, is comprised of a mask (44) of a photoreactive transducer (52) having at least one photoelectric parameter which varies as a function of incident light from the display of character information striking the transducer, and a signal circuit element (92) responsive to a variation in the photoelectric parameter in communication with the mask for developing a characteristic logic pulse indicative of the position of one or more character locations within the array upon a touch thereof and the coincident presence of character information thereat (48).