FLAT PANEL DISPLAYS.

The electronic display up to this date has been based primarily on the use of the cathode-ray tube. While this device has many meritorious features, it requires a high ratio of depth to display area diagonal for adequate displays. This is particularly true in many military applications. The usual military need to conserve volume and weight has, therefore, resulted in considerable emphasis on achieving flat panel displays. Many approaches have been pursued based on both light reflecting or transmitting and light generating approaches. The dc electroluminescent diode is a leading contender among the solid-state devices proposed for matrix displays. This may lead to a solution of particular display problems, but limitations in light output, persistence, and control characteristics together with cost indicate that other approaches should be continued to be considered. A flat panel display device based on the electron tube art but using matrix address techniques to produce an electron beam at the desired display point would solve some of these display problems. Realization of this device is dependent upon a suitable cathode. A design based on the field-emitting asperity in a cavity and one using photoemissive strips are outlined. Author