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:
Jun. 01, 2004
Filed:
Mar. 21, 2001
Applicant:
Inventors:
Shindo Watanabe, Aichi, JP;
Masahiro Konishi, Aichi, JP;
Assignee:
NGK Spark Plug Co., Ltd., Nagoya, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
F23Q 7/00 ;
U.S. Cl.
CPC ...
F23Q 7/00 ;
Abstract
A ceramic heater includes a silicon nitride ceramic substrate and a heating member embedded in the silicon nitride ceramic substrate. An Al-thickened layer is formed in a surface layer portion of the silicon nitride ceramic substrate. The Al-thickened layer has an Al concentration higher than that of an internal layer portion of the silicon nitride ceramic substrate. The Al-thickened layer assumes such a graded composition structure that the Al concentration increases toward the surface of the silicon nitride ceramic substrate.