Patent ID: 6164744
Filing Date: 2000-12-26
Classification: B41J,G01F

Abstract:
A method of monitoring a state of a reservoir made of electrically insulating material containing a product which is normally electrically conductive and having a product storage cavity and a product outlet channel communicating through one end thereof with said storage cavity, comprising:connecting the other end of the channel to a predetermined potential;defining a first measurement procedure comprising application of a first electrical signal to said storage cavity and detecting a first measurement signal, said first electrical signal being chosen so that said first measurement signal has a first characteristic varying mainly with the quantity of product contained in said storage cavity, and there is chosen, for said first characteristic, a first range of values corresponding to quantities of product greater than a minimum given quantity of said product;defining a second measurement procedure comprising application to said storage cavity a second electrical signal different from the first electrical signal and detecting a second measurement signal, said second electrical signal being chosen so that said second measurement signal has a second characteristic varying mainly with the electrical conductivity of the channel between its ends, and there is chosen, for said second characteristic, a second range of values corresponding to conductivities greater than a minimum given electrical conductivity of said channel; andexecuting at least one monitoring cycle including the following steps:the first procedure is triggered and a first item of information representing the instantaneous value of the first characteristic is captured;the second procedure is triggered and a second item of information representing the instantaneous value of the second characteristic is captured;the first item of information is compared with the first range of values of the first characteristic and the second item of information is compared with the second range of values of the second characteristic; andan abnormality procedure is triggered when the first item of information is within the first range of values and the second item of information is outside the second range of values.