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:
May. 10, 2005
Filed:
Jun. 23, 2000
Shinichi Irisawa, Shizuoka, JP;
Yoshitaka Ohshima, Shizuoka, JP;
Shinichi Irisawa, Shizuoka, JP;
Yoshitaka Ohshima, Shizuoka, JP;
Koito Manufacturing Co., Ltd., Tokyo, JP;
Abstract
An arc tube, which is capable of prolonging the life thereof by preventing occurrence of a leak caused from a crack of an arc-tube body, has the average surface roughness of each of outer surfacesAa andBa of tungsten electrodesA andB pinch-sealed to pinch seal portionsandon the two sides of a light-emission tube 20of an arc-tube bodyis set to be 3 μm or smaller. Thus, the state of pinch-sealing of the tungsten electrodesA andB to the pinch seal portionsandis brought to a state in which the two elements are engaged with small pits and projections. Therefore, great compressive stress is not left in the region adjacent to the joint surface between the pinch seal portionsandand the tungsten electrodesA andB as distinct from the conventional structure. In a case where a crack of the arc-tube bodyis formed owing to the residual compressive stress, the crack is limited to a local portion which is the region adjacent to the joint surface. As a result, the crack is not enlarged to reach the surface of the arc-tube body