Patent ID: 8237373

Claim:
A drive device for supplying electric power to a load, comprising: a primary-side rectifier circuit for rectifying a received alternating-current voltage; a first capacitor for smoothing, said rectified voltage; a transformer including a primary winding and a secondary winding; a switching element coupled to said primary winding, for converting said smoothed voltage into an alternating-current voltage by turning on and off to be supplied to said primary winding; a secondary-side rectifying-smoothing circuit for rectifying and smoothing an alternating-current voltage induced at said secondary winding to be outputted to said load; a switching control circuit for turning on and off said switching element by supplying a drive voltage to a control electrode of said switching element; and a bias circuit for supplying a bias voltage to the control electrode of said switching element, based on a voltage induced at said primary winding, wherein said bias circuit includes: a second capacitor connected between a first end of said primary winding and the control electrode of said switching element, and a diode connected, a second end of said primary winding and a connection node of the control electrode of said switching element and said second capacitor.