Light-emitting device
Provided is a light-emitting device capable of turning on a plurality of light sources with a simple configuration. The light-emitting device includes n (n≥2) light sources, n power supply circuits each provided for the n light sources, and a switch provided between a ground-side node of each of the n light sources and a ground. Each power supply circuit generates a power supply voltage for a corresponding one of the n light sources on the basis of a first signal, and stops generating the power supply voltage on the basis of a second signal, and the switch is turned on the basis of a light-on instruction and is turned off on the basis of a light-off instruction when the power supply voltage for the one light source is generated.
1 . A light-emitting device comprising:
n (n≥2) light sources;
n power supply circuits each provided for the n light sources, each of the n power supply circuits includes:
a first capacitor that generates the power supply voltage, and
a charge-discharge circuit that charges the first capacitor on the basis of the first signal and discharges the first capacitor on the basis of the second signal;
a switch provided between a ground-side node of each of the n light sources and a ground;
a second capacitor provided between the ground-side node of each of the n light sources and the switch; and
a resistor connected in parallel to the second capacitor,
wherein each power supply circuit generates a power supply voltage for a corresponding one of the n light sources on the basis of a first signal, and stops generating the power supply voltage on the basis of a second signal,
the switch is turned on on the basis of a light-on instruction and is turned off on the basis of a light-off instruction when the power supply voltage for the one light source is generated, and
a capacity of the first capacitor is larger than a capacity of the second capacitor.
2 . The light-emitting device according to claim 1 , further comprising
wherein the resistor is provided between the charge-discharge circuit and the first capacitor.
3 . The light-emitting device according to claim 2 , further comprising:
a control circuit that outputs the first and second signals to each of the n power supply circuits and controls each of the n power supply circuits,
wherein the control circuit
controls first and second power supply circuits of the n power supply circuits such that the first capacitor of the second power supply circuit is charged when the first capacitor of the first power supply circuit is discharged.
4 . The light-emitting device according to claim 1 , wherein
the capacity of the second capacitor is 1000 pF or more.
5 . The light-emitting device according to claim 1 , wherein
the light source includes any of a laser diode or a light emitting diode, and an optical member that adjusts distribution of light from the any of the laser diode or the light emitting diode.