LIGHTING DEVICE FOR HIGH INTENSITY DISCHARGE LAMP, PROJECTOR AND LIGHTING METHOD FOR HIGH INTENSITY DISCHARGE LAMP

摘要

A lighting device for a high intensity discharge lamp is designed to reduce the wear and tear of the projection of the tip of an electrode by controlling electric power at the time of starting up the lamp. In the lighting device that includes a detection means for detecting or calculating a lamp voltage, an electric current, and the electric power, and a control means for controlling a power supply means in accordance with the result of detection or calculation, the control means is equipped with a constant power control means and a constant current control means. After the lamp lighting is stabilized, the constant current control means operates when the lamp voltage is less than V0; the constant power control means to which the set reference electric power equal to the rated lamp electric power is applied operates when the lamp voltage is greater than or equal to V0. During the period of start-up, the constant current control means operates when the lamp voltage is less than or equal to V1 (V10); the constant power control means to which the set reference electric power less than the rated lamp electric power is applied operates when the lamp voltage is greater than V1; the constant power control means to which the set reference electric power equal to the rated lamp electric power is applied operates when the lamp voltage is greater than V11 (V011).