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. 16, 1997
Filed:
May. 17, 1995
Shinji Inukai, Yokohama, JP;
Kazuo Takita, Yokosuka, JP;
Makoto Nishizawa, Yokosuka, JP;
Akira Itoh, Yokohama, JP;
Kazuyoshi Okamura, Yokosuka, JP;
Kazuiki Uchida, Fujisawa, JP;
Takayuki Aoki, Yokosuka, JP;
Kazuhiko Yoshikawa, Yokohama, JP;
Akihiro Yonezawa, Yokosuka, JP;
Hiroki Sasaki, Yokohama, JP;
Toshiba Lighting & Technology Corporation, Tokyo, JP;
Abstract
In a discharge lamp having a discharge medium sealed in a discharge tube assembly including electrodes for producing a discharge, a nitride layer is formed on a surface of an envelope tube of the discharge tube assembly. The nitride layer is formed by substituting an oxygen component of an oxide constituting the tube wall of the envelope tube with nitrogen, and exhibits a continuous and smooth reduction in nitride content in the direction of depth. This chemically stable nitride layer prevents a reaction between the discharge medium and the tube wall material, and removal or injection of the discharge medium. In addition, since the nitride layer also exhibits a continuous change in thermal expansion coefficient in the direction of depth, the thermal stress is reduced, and cracking, peeling, removal, and the like do not occur.