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The quality, brightness and contrast of the image formed by a rear projection microdisplay system are strongly affected by the choice of the projection screen. Careful screen selection is necessary to achieve optimal performance for a given application. Critical image quality data such as resolution, image noise, diffuse reflectance, and gain have been measured for a representative group of commercially available screens. The correlation between screen efficiency and image noise is discussed, with particular relevance for close-viewing rear projection display applications. The nature of the image noise is probed and is found to vary with the screen type.

The goal of this contract was to apply chip on glass wire bonding and connection techniques to flat panel displays. This would considerably lower the cost of completed panels by eliminating individual driver chip packaging and as many as 3000 connections for a 640 x 480 pixel display. In addition, there would be benefits in size and reliability. The effort was able to successfully demonstrate that the process could be compatible with the structure and materials present in a flat panel display. A number of displays were fabricated and tested. The reliability of the drive chips proved to be a limiting factor, due to insufficient testing before installation. At present it is cost effective for displays smaller than 640 x 480; however, as the quality of the chips increases, it is expected to become cost effective to use the techniques developed in this program for larger displays.

In the past, flat panel displays usually required multiple printed circuit boards to contain the display driver ICs and the circuitry that communicates with the CPU and/or system. The result was a relatively bulky monitor package, compared to the thinness of the flat panel display element alone. An electroluminescent display element, for example, is less than .20 inches thick. However, when packaged with circuit boards, bezel, etc., the complete monitor depth exceeded 2 inches. Compared with a standard CRT, a 2-inch EL display represents significant volume savings. However, an EL display of this size still lacks the packaging flexibility required for ultra-port,ble designs where the entire display component cannot exceed the depth of a product's front panel, knobs, and switches.