ELECTRONIC LIGHTING DEVICE

摘要

PURPOSE:To obtain linear light adjustment characteristic of an electronic lighting device by correcting and converting the nonlinear frequency characteristic of a main circuit to a linear one by means of the characteristic curve of a light adjusting circuit. CONSTITUTION:In a light adjusting circuit 6, a PWM signal supplied from the outside is compared to a lamp current detection signal from a load current detecting circuit 5 so as to control brightness and the like of a discharge lamp 9 via a switching control circuit 7. A diode 15 used for correcting characteristics is provided in the light adjusting circuit 6 and the modulation factor of the PWM signal is converted by the forward characteristic of the diode 15 to a detection signal having nonlinear characteristic and nonlinear frequency characteristic of the switching control circuit 7 and the like is corrected into a linear one. Thereby linear light adjustment characteristic can be obtained as to linearly varying PWM signals even when frequency characteristic of the main circuit is not linear.