DIMMING CIRCUIT

PURPOSE:To provide a dimming circuit by which a comparator can be suppressed from being inverted in a moment and a dimming loop system can be stabilized. CONSTITUTION:This dimming circuit superimposes a dimming signal on a triangular wave from an oscillator 3 by a mixer 4 and compares it with a reference signal from a reference voltage generating source 5 by the comparator 6, therefore, the output of the comparator 6 is not inverted in a moment when the dimming signal traverses the reference signal, and a stationary state can be obtained gradually by changing a duty in the neighborhood of the comparator. Therefore, the oscillation of the dimming loop system can be suppressed, which stabilizes the system.