GB1404321A - Electric lighters - Google Patents

Abstract

1404321 Ignition systems PROCESS AUTOMATION Ltd and DUNHILL LIGHTERS Ltd 12 July 1972 [13 July 1971 7 June 1972] 32869/71 and 26546/72 Heading F1B [Also in Division F4] An ignition circuit for a smoker's lighter powered by at least one electric cell comprises a capacitor C1 to store energy for the production of a spark, a capacitor discharge circuit including spark electrodes IE for igniting fuel from the burner assembly, a manually operable switch SW1 actuable for the production of a spark, and a capacitor charging circuit including semiconductor switching means which is switched to a first state by a signal produced on closure of switch SW1 and to a second state by a return signal derived from discharge of the capacitor and which in the first state allows the capacitor charging circuit to operate and in the second state stops it operating. The semi-conductor switching means comprises transistors VT3, VT4 forming a complementary pair so that closure of switch SW1 turns on both transistors. Voltage supplied by cells E is applied to an inverter comprising a multi-vibrator the feedback for which is obtained from a winding P2 of a step-up transformer T 1 the output of which is connected via rectifier D1-D4 to the capacitor C1. Capacitor C1 discharges into a step-up transformer T2, the discharge being controlled by a thyristor D5 and its triggering diode D6. Discharge of capacitor Cl results in transistors VT3 and VT4 being turned off via capacitor C3 thereby stopping base current to transistors VT1, VT2. A capacitor C2 is also charged and the charge decays through resistances R1, R2 so that transistors VT3, VT4 are maintained off until switch SW1 is reactivated.