Discharge lamp

Abstract

A discharge lamp includes a cathode and an anode which face each other in an arc tube, wherein the cathode is made of tungsten in which thorium oxide is doped. The cathode has a cylindrical body portion, a tip portion having a cone shape, and a middle portion formed between the body portion and the tip portion, wherein an angle θ1 of the tip portion is set to a range of 55 degrees≰θ1≰65 degrees, and an angle θ2 formed by side faces of the middle portion is smaller than that of the tip portion.

Description

technical field [0001] The present invention relates to a xenon lamp used as a light source in a projector using, for example, DLP (registered trademark) (Digital Light Processing: Digital Light Processing) technology. Background technique [0002] Fig. 6 is a diagram showing a structure disclosed in JP 2005-142071 A as a conventional discharge lamp. The discharge lamp 1 includes a bulb made of a quartz glass luminous tube 2 and a sealed tube 3 , and a cathode 4 and an anode 5 provided to face each other inside the luminous tube 2 . The cathode 4 and the anode 5 are supported by a tungsten electrode rod 6 . In addition, a holding cylinder 7 made of cylindrical quartz glass having a through-hole extending in the axial direction is fixedly provided inside the sealed tube 3 . The electrode rod 6 is inserted and held in the holding cylinder 7 and is sealed in the sealed tube 3 with a high-low seam joint glass 8 . The electrode rod 6 protrudes and extends from the outer end of...

AI Technical Summary

Problems solved by technology

However, if the distance between the cathode 4 and the anode 5 is increased or the diameter of the tip of the tip portion 22 is increased, the expansion and contraction of the arc will not occur, but since the amount of light decreases significantly, the brightness of the light source cannot be increased.

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