| 摘要 |
PROBLEM TO BE SOLVED: To improve an operating characteristic by controlling a discharge lamp. SOLUTION: A lamp input power waveform is amplitude-modulated and formed into a pulse. In this way, both stabilization of an arc and a color characteristic of a lamp 10 are controlled. For stabilizing the arc, an AC input waveform is amplitude-modulated with an amplitude modulator 103 by a periodic sweep AC waveform such as a sinusoidal wave, a serrated wave and a square wave and combination of these waves. Here, a sweep can be formed as a pattern. A sweep waveform can be swept generally by about 20 to 60kHz, a useful sweep band is about 40 to 50kHz. By modulation thus performed, the arc is centered, shrinked and stabilized. In addition to this stabilization, the color characteristic of the lamp is controlled to be adjusted, so as to generate the input waveform of the lamp into a pulse. |
