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AssigneeMatsushita Electronics Corporation
InventorsNobuyosi Takeuti, Yoshiki Kitahara, Takeharu Tsutsumi
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The present invention provides a high pressure discharge lamp which is provided with a discharge tube containing a pair of electrodes therein and being filled with mercury, an inert gas and a halogen gas, the amount of the mercury filled being 0.12 to 0.35 mg/mm3, the halogen gas being at least one gas selected from the group consisting of Cl, Br and I and being present in an amount of 10−7 to 10−2 μmol/mm3, and the electrodes being mainly composed of tungsten, and the tungsten as a material of the electrodes contains not more than 12 ppm of potassium oxide (K2O). In such a high pressure discharge lamp, blackening of the discharge tube due to the potassium oxide (K2O) contained in the tungsten, and decrease in illumination maintenance can be prevented, thus providing a high pressure discharge lamp with a long lifetime, a lighting optical apparatus using the high pressure discharge lamp as a light source, and an image display system using the lighting optical apparatus. In another aspect, the amount of —OH in the glass of the discharge tube is less than 3 ppm. In a further aspect, the discharge lamp has a restriking voltage of less than 20 V.
A high pressure discharge lamp which is provided with a discharge tube containing a pair of electrodes therein and being filled with mercury, an inert gas and a halogen gas, an amount of the mercury filled being 0.12 to 0.35 mg/mm3, the halogen gas being at least one gas selected from the group consisting of Cl, Br and I, and being present in an amount of 10−7 to 10−2 μmol/mm3, and the electrodes mainly being composed of tungsten, wherein the tungsten contains not more than 12 ppm of potassium oxide (K2O).
Alighting optical apparatus comprising
An image display system comprising
Dependencies are inferred from the claim text.