Other numeric-display technologies concurrently in use included backlit columnar transparencies ("thermometer displays"), light pipes, rear-projection and edge-lit lightguide displays (all using individual incandescent or neon light bulbs for illumination), Numitron incandescent filament readouts,[11] Panaplex seven-segment displays, and vacuum fluorescent display tubes. Before Nixie tubes became prominent, most numeric displays were electromechanical, using stepping mechanisms to display digits either directly by use of cylinders bearing printed numerals attached to their rotors, or indirectly by wiring the outputs of stepping switches to indicator bulbs. Later, a few vintage clocks even used a form of stepping switch to drive Nixie tubes.