Lighting device and luminaire

摘要

A lighting device includes a DC/DC converter (step-down chopper circuit) and a control circuit that includes a correction circuit. The correction circuit corrects the timing at which a switching element included in the DC/DC convertor is turned OFF based on a voltage value across a solid-state light-emitting element (LED unit). The correction is made such that an average value of a current flowing through an inductor included in the DC/DC converter is within a predetermined range regardless of a voltage value across the solid-state light-emitting element.

主权项

1. A lighting device that is connected to a DC power source to supply a current to a solid-state light-emitting element, the lighting device comprising:
a DC/DC converter; and a control circuit, wherein the DC/DC converter includes: a switching element that is connected to the DC power source and is turned ON and OFF; an inductor that is connected in series with the switching element, and through which the current from the DC power source flows when the switching element is ON; a diode that supplies, to the solid-state light-emitting element, the current released from the inductor; and a current detection circuit that detects a current flowing through the switching element and outputs a detected current value that is a value of the current detected, the control circuit includes: a drive circuit that turns the switching element ON and OFF; a voltage detection circuit that detects either one of a voltage across the solid-state light-emitting element and a voltage across the inductor, and outputs a detected voltage value that is a value of the voltage detected; and a correction circuit that corrects a timing at which the drive circuit turns OFF the switching element, when the drive circuit detects that the inductor has finished releasing energy, the drive circuit turns ON the switching element, and when the detected current value reaches a predetermined current command value, the drive circuit turns OFF the switching element, and the correction circuit corrects the timing at which the drive circuit turns OFF the switching element, based on the detected voltage value.