Patent ID: 6339335
Filing Date: 2002-01-15
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, comprising:providing a resonant circuit having a capacitive arrangement comprising at least part of the reservoir, the resonant circuit being connected to an excitation signal generator; defining a measurement procedure according to which a plurality of excitation signals is applied to the resonant circuit having different frequencies included in a predetermined frequency range and a plurality of measurement signals is received at a measuring point in response to excitation signals, the predetermined frequency range being chosen so as to contain frequencies at which the resonant circuit is in resonance for a plurality of values of the quantity of product within a predetermined operating range; defining a processing procedure according to which the value of a characteristic of the resonant circuit is identified from the plurality of measurement signals, a measurement of resistance formed by the product contained in the reservoir is derived from the value, and an instantaneous value of an item of information representing the quantity of product contained in the reservoir is derived using a pre-established correlation relationship; effecting at least one determination cycles including triggering of the measurement procedure and the processing procedure; and capturing the instantaneous value of the item of information.