Light-emitting element drive circuit and laser processing machine

A light-emitting element drive circuit to drive a light-emitting element, comprising:

• a first DC power supply to hold a first voltage, the first DC power supply being connected to an anode of the light-emitting element so as to be able to apply the first voltage to the anode of the light-emitting element;
• a second DC power supply connected to the anode of the light-emitting element so as to be able to apply a second voltage lower than the first voltage to the anode of the light-emitting element;
• a first switch element to switch on and off application of the first voltage to the anode of the light-emitting element;
• and
• a linear regulator to control current flowing through the light-emitting element,
• the linear regulator including
• a second switch element through which the current flowing through the light-emitting element flows, and
• a drive unit to drive the second switch element,
• the drive unit including
• a gate drive circuit to drive a gate of the second switch element, and
• two or more constant circuits having mutually different control constants set,
• the drive unit selects one of the two or more constant circuits and connect the selected one to the gate drive circuit, according to whether a voltage applied to the light-emitting element is the first voltage or the second voltage.