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:
Sep. 17, 2002
Filed:
Jun. 26, 2000
Koito Manufacturing Co., Ltd., Tokyo, JP;
Abstract
An arc tube provided with a central sealed chamber , in which light-emitting substances are enclosed, having a pair of electrode assemblies disposed opposite to each other. The electrode assemblies are sealed in pinch seal portions . The arc tube incorporates a residual-compressive-stress layer formed on a surface of the glass layer in each of the pinch seal portions that contacts the electrode rod included in each electrode assembly. The residual-compressive-stress layer has a length greater than or equal to 30% of the axial length of a glass layer region that only contacts the electrode rod and/or an angular range greater than or equal to 180° in a circumferential direction of the electrode rod. Thermal stress (tensile stress) produced in the boundary between the glass layer and the electrode rods after the arc tube has been turned on is absorbed and dispersed by the residual-compressive-stress layer surrounding the electrode rods . Thus, any vertical crack that would result in the light-emitting substances leaking from the sealed chamber does not form in the glass layer of the pinch seal portions