STEPPED DIMMING BALLAST FOR FLUORESCENT LAMPS

摘要

A stepped dimming ballast for fluorescent lamps is provided to control an intensity of illumination step by step with a simple structure and a reliability. In a stepped dimming ballast for fluorescent lamps, a filter and rectifying circuit(1) is provided. A frequency control and switch circuit(3) supplies a high voltage to control frequency and generate/adjust a switch driving signal to a lamp load. A voltage signal sampling circuit(7) converting a variation of a conduction angle of an SCR(Silicon Controlled Rectifier) dimmer or an on/off state of normal light switch to a voltage signal periodically controls a variation of a set of operation states, archiving a multi-stepped illumination adjustment by transferring the voltage signal to a voltage signal processing circuit(6) for generating a dimming control voltage according to a designated program while the voltage signal is transferred to the frequency control and switch circuit(3) in case of the voltage signal checked as a validity change.