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:
Dec. 14, 2004
Filed:
Jun. 28, 2001
Kenichi Nishikawa, Nagoya, JP;
NGK Spark Plug Co., Ltd., Aichi, JP;
Abstract
The present application is to provide a spark plug where a marking layer under a glaze layer can form a color stably, even if the Pb amount is decreased in the glaze layer. The glaze layer is formed on an insulator of the spark plug, and the marking layer is formed under the glaze layer . The glaze layer contains, e.g., 1 to 25 mol % of a Zn component in terms of Zno and 5 mol % or lower, e.g., 1 mol % or lower of a Pb component in terms of PbO. On the other hand, the marking layer is adjusted in kinds and amounts of metallic element components in such manners that a tint seen through the glaze layer is 3 or lower in brightness specified by JIS:Z8721 as well as 3 or lower in chroma specified by JIS:Z8721, or 4 or lower in the brightness specified by JIS:Z8721 as well as 2 or lower in the chroma specified by JIS:Z8721.