Patent ID: 7772786

Claim:
A battery-powered light source device for an endoscope, comprising a DC/DC converter having: a comparator for comparing an output voltage supplied to a light source lamp with a specific reference voltage; and an adjuster circuit for adjusting the output voltage supplied to the light source lamp on a basis of the comparison result of the comparator so that a specific lamp voltage will be achieved; wherein said DC/DC converter raises or lowers a power supply voltage of an internal battery and supplies the raised or lowered power supply voltage to the light source lamp that generates illuminating light supplied to the endoscope, on a basis of the output signal of the adjuster circuit, wherein the adjuster circuit is equipped with an oscillator that generates a reference clock signal, and a modulator modulates the pulse width by being set by the reference clock signal of the oscillator and being reset by the comparison result of the comparator.