| 摘要 |
PURPOSE:To reduce the voltage required to start a lamp, improve the reliability of the lamp, and facilitate insulation countermeasures by specifying the pulse width of high-voltage pulses and the time constant of pulse attenuation respectively. CONSTITUTION:The high-frequency voltage fed from a high-frequency power source 2 and the pulse voltage fed from a pulse power source 3 are superimposed on a main power source 1 and applied to an HID lamp 4 at the time of starting. When the time constant of the attenuation of pulses is below 4mus, the pulse voltage becomes high, thus the time constant is preferably set to 4mus or above to start the lamp 4 with the voltage as low as possible. The pulse width of the high-voltage pulse is set to 1-10mus. When the pulse width is narrower than 1mus, the voltage required for the instant restart becomes high, when the pulse width is wider than 10mus, the output of the pulse power source 3 is nonpreferably increased although the required pulse voltage is not changed. The lamp 4 is kept lighted by the main power source 1 constituted of a commercial power source, a choke coil and a capacitor after lighting. |
