Phase-controlled, multi-electrode type of ac discharge light source

Abstract

An energy-saving, high-outputting and high-efficiency, electric discharge type of illumination apparatus and associated units having thin divisional electrode pieces arranged at relatively narrow intervals on an electrode-application area, which is defined on the bottom of a flat container. The divisional electrode pieces are fixed to the electrode-application area with an intervening sheet of good electrically insulating and thermally conductive material laid therebetween. A front glass having a fluorescence coating on its inside is placed to confront the electrode-application area. Cooling water is circulated in the electrode-application area for cooling the divisional electrode pieces. A multi-poled magnet sheet arranged outside the electrode-application area is aligned with the electrode-to-electrode space. Lower frequency power supplies are connected to the divisional electrodes to supply that with voltages of the same amplitude. The power supplies are connected in the form of a star and are connected to a controller for controlling the frequency, amplitude and phase of the voltage wave. The power supply uses an insulation transformer to float the voltages appearing at the output terminals. Thus, an electric discharge appears exclusively among divisional electrodes.