DEVELOPMENT OF THIN FILM ELECTROLUMINESCENT DISPLAY TECHNIQUES.

An electroluminescent display panel of the cross-grid-matrix-type was fabricated on a 10-34 x 10-34-inch glass substrate using improved vacuum deposition procedures and a high brightness manganese-doped ZnS phosphor. This panel contained 256 x 256 active elements within an area of approximately 7 x 7 inches. Linear resolution was 36 elements per inch with a cross-conductor width of 0.020 inch and a separation of 0.007 inch. The display panel was successfully used as a viewing screen for rear-projected images. The brightness-voltage relationship of the thin film phosphor was such that a cross-suppression ratio in excess of 10,000 to 1 was achieved with an excited element brightness of 100 ft-L. Performance measurements indicated that the optimum drive frequency was about 15 kHz. For pulsed operation, a burst frequency of 37.5 Hz, a carrier frequency of 15 kHz, and a duty cycle of 0.25 percent gave an average brightness of a few foot-Lamberts. Useful operating lifetime of several hundred hours under the above conditions was indicated by preliminary data. The variation in brightness uniformity over a group of cells near the center of the panel was less than 7 percent at an average brightness level of 16 ft-L. A brightness reduction of about 12 percent was observed at a single cell when the contacting configuration was varied on the stannic oxide electrode. Author