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:
May. 18, 2010
Filed:
Jul. 30, 2007
Gerhard Nikolaus, Engerwitzdorf, AT;
Gerhard Nikolaus, Engerwitzdorf, AT;
E+E Elektronik Ges.m.b.H., Engerwitzdorf, AT;
Abstract
A circuit configuration for measuring air humidity includes a measuring system which includes an oscillator unit and a signal-processing unit, as well as a frequency-determining impedance, which is determined largely by a parallel connection of a capacitive humidity sensor and a parasitic resistance. The frequency-determining impedance is connected to the oscillator unit, which includes an oscillator having an oscillation frequency that is a function of the frequency-determining impedance. The oscillator unit includes a switchable impedance, which can be connected in addition to the frequency-determining impedance, the oscillator thereby being switchable from a first frequency range to a second frequency range. An oscillator signal having the oscillation frequency of the oscillator is supplied to the signal-processing unit in which the frequency of the oscillator signal is able to be measured, and a correction value to compensate for the influence of the parasitic parallel resistance on the oscillation frequency of the oscillator is ascertainable as a function of the difference between a first measurement of the frequency of the oscillator signal in the first frequency range and a second measurement of the frequency of the oscillator signal in the second frequency range.