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:
Jan. 01, 2002
Filed:
Apr. 10, 2000
Kenichi Nishikawa, Aichi, JP;
Yutaka Tanaka, Aichi, JP;
Toshitaka Honda, Aichi, JP;
Makoto Sugimoto, Aichi, JP;
NGK Spark Plug Co., Ltd., Nagoya, JP;
Abstract
In a spark plug ( ), the resistor composition constituting a resistor ( ) contains semiconductive ceramic particles, offering a superior load life characteristic. Also, the value of (&agr; )/&agr; >=−0.30, where a value of electric resistance between a terminal ( ) and a center electrode ( ) is &agr; at 20° C. and &agr; at 150° C., so that deterioration of the radio frequency noise prevention performance at high temperatures can be effectively suppressed. The resistor composition contains semiconductive ceramic particles whose temperature coefficient of electric resistance shows a positive value, or a negative value of relatively small absolute value, (e.g., TiO particles having a rutile type crystalline structure, titanate or zirconate of alkali earth metal elements, titanium suboxide, etc.), or titanium metal. Thus, the invention provides a resistor-incorporated spark plug which is enabled to offer a stable load life characteristic even when a high load acts thereon, and which is unlikely to deteriorate in the radio frequency noise prevention performance even under high temperatures.