TREIBERSCHALTUNGSANORDNUNG FUER EIN VAKUUMANZEIGESYSTEM

A vacuum fluorescent display system for displaying a plurality of illuminable characters includes a plurality of segmented anodes, at least one cathode filament, a plurality of control grids interposed between the anodes and the cathode filament and circuitry for controllably powering the cathode filament and for sequentially driving the control grids whereby selected segments of the anodes are sequentially illuminated and the luminous intensity of the segments of each of the anodes is substantially the same. The cathode filament is controllably powered by removing and applying heating power in response to driven and undriven states respectively of the control grids. By controlling when heating power is applied to the cathode filament the voltage along the cathode filament is the same for each anode when the selected anode segments are sequentially illuminated thereby substantially eliminating variation in luminous intensity.