Patent ID: 6351716
Filing Date: 2002-02-26
Classification: B41J,G01F

Abstract:
Method of determining the quantity of an electrically conductive product contained in a reservoir made of electrically insulating material having at least one storage cavity, according to which:a resonant circuit is formed having a capacitive arrangement comprising at least part of this reservoir; this resonant circuit is connected to an excitation signal generator; a measurement procedure is defined according to which a plurality of excitation signals is applied to this resonant circuit having different frequencies included in a predetermined frequency range and a plurality of measurement signals are taken off at a measuring point in response to these excitation signals, this frequency range being chosen so as to contain the frequencies at which the resonant circuit is in resonance for a plurality of values of the quantity of product within a predetermined operating range; a processing procedure is defined consisting of identifying the instantaneous resonant frequency of the resonant circuit from this plurality of measurement signals, measuring the width, for a given amplitude level, of the resonance peak and deriving therefrom an item of information representing the quantity of product contained in the storage cavity, this amplitude level being chosen so that there exists a univocal correlation law between the width of the resonance peak and this item of information when the quantity of product is within the said operating range; at least one determination cycle is effected, consisting of triggering the measurement procedure and the processing procedure, and capturing the instantaneous value of the said item of information.