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:
Mar. 15, 1988
Filed:
Jun. 17, 1986
Andras Gedeon, Taby, SE;
Icor AB, Bromma, SE;
Abstract
Apparatus for determining the proportion of a given gas component in a gas mixture, comprising a piezoelectric crystal provided with a surface layer containing a substance capable of selectively and reversibly adsorbing said gas component, and being so arranged that the gas mixture can be brought into contact with said surface layer. The crystal is incorporated in an oscillator circuit which produces an output signal representing the oscillating frequency of the crystal, and therewith the proportion of the given gas component in the gas mixture. For compensating the temperature dependency of the surface-layer adsorption of the relevant gas component, a thermistor (R.sub.T) is arranged to be influenced by the same temperature variations as the piezoelectric crystal. Further, the output signal (S) of the oscillator circuit is connected to the input of an amplifying circuit, which incorporates the thermistor (R.sub.T) and is so constructed that the degree of amplification of the circuit is dependent on the resistance of the thermistor in a manner such that the output signal (V.sub.U) deriving from the amplifying circuit is substantially independent of temperature variations of the surface layer of the piezoelectric crystal.