Patent ID: 9439264
Filing Date: 2016-09-06
CPC Classification: H05B

Claim Text:
1. A light-emitting-element lighting circuit for dimming a light emitting element by a PWM dimming signal, the lighting circuit comprising: a PWM dimming signal generating unit adapted to generate the PWM dimming signal of a duty ratio corresponding to an input dimming signal by performing a summation of AC wave signals including a fundamental wave and harmonics that are different integer multiples of a fundamental frequency of the fundamental wave, wherein the fundamental frequency is in an audible frequency range and is lower or higher than a frequency in the audible frequency range, at which a sound pressure level generated from the light emitting element is at maximum, and wherein the PWM dimming signal is represented by the following equation: where I 0 is a maximum amplitude value of a current, n is an integer equal to or greater than 1, and Ton/T is an ON duty ratio of a square wave.