Patent ID: 9226353
Filing Date: 2015-12-29
Classification: H05B,Y02B

Abstract:
1. A lighting device comprising: a first switching power supply circuit and a second switching power supply circuit which are connected in parallel to an input DC power supply to drive a first semiconductor light emitting element emitting a first light having a first color temperature and a second semiconductor light emitting element emitting a second light having a second color temperature which is different from the first color temperature; a high frequency oscillation circuit which generates a high frequency square wave signal serving as an on/off switching signal of each of the first switching power supply circuit and the second switching power supply circuit; a low frequency oscillation circuit which generates a first low frequency square wave signal and a second low frequency square wave signal; a first gate circuit connected to the first switching power supply circuit having a first input to which the high frequency square wave signal is inputted and a second input to which the first low frequency square wave signal is inputted; and a second gate circuit connected to the second switching power supply circuit having a first input to which the high frequency square wave signal is inputted and a second input to which the second low frequency square wave signal is inputted, wherein each of the first low frequency square wave signal and the second low frequency square wave signal has a frequency lower than that of the high frequency square wave signal, wherein the first gate circuit and the second gate circuit determine whether the high frequency square wave signal is supplied as the on/off switching signal to the first switching power supply circuit and the second switching power supply circuit based on the first low frequency square wave signal and the second low frequency square wave signal, respectively, wherein on/off duties of the first low frequency square wave signal and the second low frequency square wave signal are complementarily changed such that a color temperature of a mixed light of the first light and the second light is varied, and wherein a brightness of each of the first semiconductor light emitting element and the second semiconductor light emitting element is changed by adjusting an on/off duty of the high frequency square wave signal.