Electronic gas discharge tube igniter

Claim 1

An igniter device for use with a gas discharge tube having filament means which must be brought up to operating temperature before the tube may conduct current, a source of alternating current driving said tube, and means for controlling current through said tube once same is ignited, the igniter device comprising, in combination: gate-controlled semiconductor switching means for effecting heating of the filament means to initiate current conduction by the tube and thereafter to remain in non-conductive state, said switching means having a gate electrode and having a currentconducting path adapted to connect the filament means in series with the source whereby said switching means is selfextinguishing at every zero crossing of the source; and control means connected to said gate electrode for causing the switching means to conduct during half cycles of the source until the tube is ignited and thereafter to be ineffective to cause conduction of said swiTching means during current conduction by the tube, said control means comprising a semiconductor switching diode, and a voltage divider circuit connected in parallel with said switching means, said voltage dividing circuit including first capacitor means for causing conduction of said switching diode when the tube is not conducting and second capacitor means in series with said first capacitor means for maintaining the juncture between said first and second capacitor means below that value of voltage effective to cause conduction of said switching diode when the tube is conducting, said switching diode being connected between said juncture and said gate electrode.