DRIVING CIRCUIT, ILLUMINATION LIGHT SOURCE, AND ILLUMINATION DEVICE

摘要

A driving circuit includes a rectifying and smoothing circuit that rectifies an AC dimming signal, and a voltage conversion circuit (1A) including: a switching element having a source connected to a low-potential output terminal of the rectifying and smoothing circuit; a diode having an anode connected to a high-potential output terminal of the rectifying and smoothing circuit; an inductor disposed between the diode and a drain of the switching element; an oscillation controller; a capacitor that is charged by receiving magnetic energy from the inductor when the switching element is OFF, and discharges to a load when the switching element is ON; and a power control circuit that applies a voltage corresponding to a voltage at a high-potential terminal of the capacitor to the oscillation controller as a supply voltage for driving the oscillation controller.

主权项

1. A driving circuit that converts a phase-controlled AC dimming signal into a DC signal according to a dimming level, and causes a light-emitting device to emit light, using the DC signal, the driving circuit comprising:
a rectifying circuit that rectifies the AC dimming signal; and a voltage conversion circuit that is connected between a low-potential output terminal and a high-potential output terminal of the rectifying circuit, and converts an input voltage from the rectifying circuit and applies a DC voltage to the light-emitting device, the voltage conversion circuit including: a switching element having one end connected to the low-potential output terminal of the rectifying circuit; a first diode having an anode connected to the high-potential output terminal of the rectifying circuit; a first inductor having one end connected to a cathode of the first diode, and another end connected to another end of the switching element; an oscillation controller that controls a pulse signal to be supplied to a control terminal that controls ON and OFF of the switching element; a first capacitor that is charged by receiving magnetic energy from the first inductor when the switching element is OFF, and discharges to the light-emitting device when the switching element is ON; and a power control circuit that applies a voltage corresponding to a voltage at a high-potential terminal of the first capacitor, to the oscillation controller as a supply voltage for driving the oscillation controller, wherein the driving circuit alternates between a first state and a second state, the first state being a state in which when the switching element is ON, the first capacitor discharges and the magnetic energy is stored in the first inductor with a current flowing from the rectifying circuit to the first inductor through the first diode, the second state being a state in which when the switching element is OFF, the magnetic energy stored in the first inductor is discharged to the first capacitor, and the current flows from the rectifying circuit to the first inductor through the first diode to compensate for the magnetic energy discharged from the first inductor.