| 摘要 |
PROBLEM TO BE SOLVED: To provide a lighting method of a high-pressure discharge lamp hardly deteriorating illuminance of a lamp unit, especially, one mounting the high-pressure discharge lamp on a reflecting mirror. SOLUTION: After starting discharge of a lamp, a constant current control is carried out so that a lamp current is 4A (S3). If a relation between a temperature t(°C) of a tip point of an electrode monitored by an infrared-ray camera and a temperature T(°C) at stable lighting satisfies: t≤1.1T (S4:YES), constant current control at 4A is continued (a step S5), and if a lamp voltage rises up to 62.5 V or more, a step is moved to a constant power control at a rated power value of 250 W (S7:YES, S9). If t>1.1T at the step 4 (S4:NO), a step is changed over to a constant current control of 2.5 A (S6). With this, excessive temperature rise at the tip of the electrode during an initial lighting period is restrained, and an increase of an arc length due to dissolution of the electrode tip can be restrained, so that no degradation of illuminance takes place. COPYRIGHT: (C)2009,JPO&INPIT |
