Patent ID: 8547027

Claim:
An LED drive circuit comprising: a rectifying circuit for rectifying AC commercial power; a light-emitting circuit which includes an LED array; and a current supply circuit which includes a capacitor, a time constant adjusting element, and a diode; wherein: the discharge time constant of said current supply circuit is set longer than the charge time constant of said current supply circuit, and said capacitor is charged by an output of said rectifying circuit; during a period of time when the magnitude of AC commercial power supply voltage is larger than the light emission threshold of said LED array, current to said light-emitting circuit is supplied mostly from said rectifying circuit, and during a period of time when the magnitude of AC commercial power supply voltage is not larger than the light emission threshold of said LED array, current to said light-emitting circuit is supplied from said current supply circuit; an anode of said diode is connected to an output of said rectifying circuit and a cathode of said diode is connected to a high-voltage side terminal of said capacitor; and said time constant adjusting element and said diode are connected in parallel.