PURPOSE: To prevent irregularity of output of each inverter apparatus owing to waveform alternation of a square wave electric voltage signal by attaching an a waveform rectifying circuit to rectify waveform of the square wave electric voltage signal to an inverter apparatus.
CONSTITUTION: A waveform rectifying circuit 15 is attached to a light modulation controlling circuit 13 in each inverter apparatus 1 in a prior stage. Inlet terminals of the waveform rectifying circuit 15 are connected with signal wires l3, l4 and output terminals are connected with the light modulation controlling circuit 13. The waveform rectifying circuit 15 comprises a level comparators whose output voltage becomes high level when input voltage goes over a first prescribed level and becomes low level when input voltage goes under a second prescribed level. Consequently, if a plurality of inverter apparatus 1 are connected with the same signal wires l3, l4 in parallel and outputs of them are simultaneously changed, irregularity of output of each inverter apparatus 1 is prevented by attaching a waveform rectifying circuit 15 to an inverter apparatus 1.
SAKO HIROYUKI
OKAMOTO FUTOSHI
