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:
Apr. 15, 2003
Filed:
Sep. 19, 2000
Hamamatsu Photonics K.K., Shizuoka, JP;
Abstract
In order to meet various requirements for discharge tubes for use as light sources, including easiness of production, stability of discharge, long lifetime, etc. without any contradiction between them, a discharge tube of the present invention involves an improvement in the discharge tube for use as a light source constructed to effect arc discharge in a discharge gas atmosphere between a cathode , having a cathode tip portion fixed to a lead rod , and an anode opposed thereto while keeping the cathode and anode enclosed in the gas. The cathode tip portion has a cusp pointed toward the anode and consists of a refractory metal substrate of an impregnated type or a sintered type containing an electron-emissive material, and a refractory metal coating covering the surface except at the tip portion of the cusp. At the tip portion of the cusp in the cathode tip portion, the metal substrate is exposed without being covered by the coating, or the coating is made so thin or porous as to substantially expose the metal substrate.