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:
Oct. 30, 2001
Filed:
Feb. 15, 2000
Hideki Ishikawa, Aichi, JP;
Yoshikuni Sato, Aichi, JP;
Keigo Banno, Aichi, JP;
Noboru Ishida, Gifu, JP;
Takafumi Oshima, Aichi, JP;
NGK Spark Plug Co., Ltd., Aichi, JP;
Abstract
A gas concentration sensor comprises an ultrasonic element,opposite a reflection surface,A depression,is formed on an edge portion of a reflection surface,which is in contact with a side wall of a measurement chamber,such that a bottom surface of the depression,is substantially in parallel with the reflection surface,The distance between the ultrasonic element,and the edge portion of the reflection surface,becomes greater than the distance between the ultrasonic element,and a central portion of the reflection surface,As a result, an indirect wave, which impinges obliquely on the side wall of the measurement chamber,and propagates along the side wall, is reflected from the bottom surface of the depression,and propagates. Thus, the propagation distance of this indirect wave becomes greater as compared to the case where the reflection surface,is flat, so that the indirect wave is not combined with a direct wave in the vicinity of a modulation point of the direct wave. That is, since the modulation point of the direct wave can be detected accurately, a time interval between a modulation point of a transmitted wave and that of a received wave can be measured as the propagation time of an ultrasonic wave, thereby enabling accurate determination of gas concentration.