A display in which various combinations of segments may be activated by applying voltages to produce any desired numerical or other characters: Electroluminescent display devices present data, usually in the form of numbers or letters, when alternating current is applied to their electroluminescent segments.

A tool with an extra semiconductor control layer which permits storing of images for controllable periods of at least an hour: The desired image is projected onto the electroluminescent display screen with ultraviolet light, and it is completely erased with infrared radiation.