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. 20, 1994
Filed:
Jun. 02, 1992
Hideaki Yagi, Nagoya, JP;
Katsuhiko Horii, Nagoya, JP;
NGK Spark Plug Co., Ltd., Nagoya, JP;
Abstract
In a method of measuring humidity by using an electrochemical cell, the method comprises applying a voltage across the pair of electrodes to obtain a characteristic curve between the voltage applied and electrical current. The characteristic curve starts with a first flat portion in which a first diffusion limit current remains generally constant within a predetermined voltage range and passes through a point of inflection in which a second differential derivative of the characteristic curve falls on zero at certain voltage, and ends up with a second flat portion in which a second diffusion limit current remains generally constant within a predetermined voltage range. The point of the inflection is uniquely determined regardless of a humidity level of the gas at a constant temperature and oxygen concentration. The humidity level in the gas is obtained by reading the point of the inflection, and the intensity of the first and second diffusion limit current and then comparing the diffusion limit current with the inflection as a reference current.