The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 03, 2005
Filed:
Mar. 31, 2003
Nobuyosi Takeuti, Hirakata, JP;
Yoshiki Kitahara, Takatsuki, JP;
Takeharu Tsutsumi, Takatsuki, JP;
Matsushita Electric Industrial Co., Ltd., Osaka, JP;
Abstract
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/mm, 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 10to 10μmol/mm, 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 (KO). In such a high pressure discharge lamp, blackening of the discharge tube due to the potassium oxide (KO) 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.