Lighting device and luminaire

摘要

A lighting device that lights up an LED and includes a DC power source, a buck converter and a control circuit. The buck converter includes a switching element, an inductor and a diode. The control circuit includes a current detection circuit that detects an electric current flowing through the switching element, a voltage detection circuit that detects a voltage across the inductor, a delay circuit that generates a delay time according to the voltage detected by the voltage detection circuit, and a drive circuit that generates and outputs a control signal to the switching element, the control signal turning OFF the switching element after a lapse of the delay time generated by the delay circuit from when the electric current detected by the current detection circuit reaches a predetermined current command value.

主权项

1. A lighting device that lights up a solid-state light-emitting element, the lighting device comprising:
a DC power source; a buck converter that is a constant current output converter, and receives an electric current from the DC power source and supplies a predetermined electric current to the solid-state light-emitting element; and a control circuit that controls the buck converter, wherein the buck converter includes: a switching element; an inductor that is connected in series with the switching element, and through which the electric current from the DC power source flows when the switching element is ON; and a diode that supplies, to the solid-state light-emitting element, the electric current released from the inductor, and the control circuit includes: a current detection circuit that detects an electric current flowing through the switching element; a voltage detection circuit that either is connected to one of end terminals of the solid-state light-emitting element and detects a forward voltage of the solid-state light-emitting element or is connected to one of end terminals of the inductor and detects a voltage across the inductor; a delay circuit that generates a delay time that is variable according to the voltage detected by the voltage detection circuit; and a drive circuit that generates and outputs a control signal to the switching element, the control signal turning OFF the switching element after a lapse of the delay time generated by the delay circuit from when the electric current detected by the current detection circuit reaches a predetermined current command value, and turning ON the switching element when the inductor releases predetermined energy.