Light source device

Light source device, comprising:

• an ultrahigh pressure discharge lamp with a silica glass discharge vessel that contains a pair of opposed electrodes spaced from each other by a distance of at most 1.5 mm, and which is filled with at least 0.15 mg/mm3 of mercury and bromine within a range from 10−6 μmol/mm3 to 10−2 μmol/mm3;
• a feed device which supplies an alternating current to the discharge lamp and operates it;
• an oval reflector which is located such that its optical axis coincides with a direction of an electrode axis of the discharge lamp and which reflects radiant light of the discharge lamp out of a front opening of the reflector;
• and
• a color wheel which proceeding from a focal position of the oval reflector is located at the position nearer the lamp and which receives the light from the reflector and divides it into color components,
• wherein each of the electrodes has an enlarged tip area with a diameter larger than a diameter of a support rod which bears the electrode and a coil part adjoining the enlarged tip area of the electrode,
• wherein for a one of the electrodes which is located on a side of the front opening of the reflector, the tip area with increased diameter has a volume W (mm3) which is related to the current supplied from the feed device in accordance with the relationship
• 0.06<W/I2<0.96,
• and
• wherein the volume of the enlarged tip area of the electrode on the side of the reflector opposite the front opening is smaller than the volume of the enlarged tip area of the electrode on the side of the front opening of the reflector.