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:
Apr. 04, 1989
Filed:
Jun. 30, 1987
Dragerwerk Aktiengesellschaft, Lubeck, DE;
Abstract
A measuring arrangement for detecting the level of combustible gases mixed with air such as methane in air includes a measuring sensor responsive to the heat-conductivity of the proportion of the gas to be detected. The effect of the ambient temperature on the heat-conductivity measurement is eliminated through a simple circuit configuration consuming low power for a measurement of heat-conductivity alone as well as for such a measurement in combination with a reaction-heat measurement. For this purpose, the heat-conductivity sensor is connected to a constant-current source. A measuring takeoff circuit for the heat conductivity is connected in parallel to the heat-conductivity sensor and is provided in the form of a series circuit including a measuring signal terminal and a compensating voltage source. The compensating voltage source generates a compensating voltage which changes in magnitude and direction in correspondence with the temperature-dependent change in the voltage drop across the heat-conductivity sensor.