ABSTRACT
Electroluminescence (EL) is the nonthermal generation of light resulting from the application of an electric field to a substance. The light-emitting substance is generally a luminescent crystal. The attributes of EL displays that make them attractive in these types of applications are mechanical ruggedness, relative insensitivity to ambient temperature, rapid display response, essentially unlimited viewing angle, compactness, and lightweight. There are four types of EL devices: ac thin film, ac powder, dc thin film, and dc powder. A matrix-addressed monochrome display is created by dividing the upper and lower electrodes into orthogonal arrays of electrode stripes. The EL device is excited locally by applying a voltage between a pair of crossing electrodes, causing an electric field to exist between them, which excite the phosphor. Patterning of the electrodes is generally accomplished either through etching or liftoff, although some early workers patterned the upper aluminum electrodes by evaporating through a shadow mask.
