An electroluminescent-piezoelectric flat-panel display device

A flat-panel, line display consisting of electroluminescent ZnS---Cu phosphors (EL) adjacent to piezoelectric voltage transformer elements (PE) has been fabricated to provide a controlled-movement luminescent light spot. Electroluminescence is excited by the electric fields generated at the surface of a piezoelectric element driven at its resonant frequency. The display is made up of thirty PE-EL units connected electrically in parallel, each unit resonating at a different frequency. Movement of the light spot over the face of the display is produced by frequency modulation of the voltages applied to the piezoelectric array, in the manner of a sweep frequency. Synchronized amplitude modulation permits the light spot to be localized and its movement to be controlled. The display has a sweep frequency range extending from 30 to 60 kc/s. PE-EL units under continuous operation generate 40 ft lamberts at 8[middle dot]8 Vrms, and can generate over 100 ft lamberts by overdriving at 40Vrms. In sweep operation at 100 c/s, the light output is 40 ft lamberts at 35 Vrms. Power consumption in this mode is less than 10 mW. EL fatigue is analyzed and minimized in this display sweep technique.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32284/1/0000351.pd