Patent ID: 6081077
Filing Date: 2000-06-27
Classification: H05B,Y10S

Abstract:
A power supply circuit for discharge lamps having a least one filament comprising:an inverter including a pair of inverter switches;a load circuit connected to the inverter and adapted to receive at least one discharge lamp having a power rating;a recognition circuit connected to the load circuit, the recognition circuit identifying the lamp connected to the load circuit by the power rating of the lamp;a switching control means connected to the inverter switches and controlling the opening and closing of the inverter switches to supply the load circuit with a high frequency alternating signal;the switching control means responsive to the recognition circuit to vary the signal supplied to the load circuit according to the power rating of the lamp;a control transformer having an auxiliary winding;wherein the recognition circuit modifies the conditions of current flow in the auxiliary winding according to the power rating of the lamp connected to the load circuita current source connected between the recognition circuit and the auxiliary winding, the current source providing current to the auxiliary winding as directed by the recognition circuit; andan auxiliary switch, the auxiliary switch being connected between the auxiliary winding and ground, the auxiliary switch being controlled by the recognition circuit to control the switching of the inverter switches to make the inverter switches simultaneously isolating.