Patent ID: 8558471
Filing Date: 2013-10-15
Classification: G03B,H01J,H05B

Abstract:
1. A light source device comprising: a discharge lamp that emits light by discharge between a first electrode and a second electrode; and a driver that supplies alternating current to the first and the second electrodes so as to maintain the discharge, and changes a duty ratio of the alternating current in accordance with a predetermined pattern, the predetermined pattern including a plurality of section periods for which the duty ratio maintains mutually different values for a predetermined period, wherein one cycle of the alternating current includes a positive polarity period and a negative polarity period for which a current value is positive and negative respectively, the driver varies the current value during a longer polarity period among the positive and the negative polarity periods, time ratio of the longer polarity period to the one cycle of the alternate current being at least 50%, and the driver varies the current value during the longer polarity period so that the current value is at a maximum at an end of the longer polarity period.