Interchangeable networks with non-linear sensors and method of producing such networks
AssigneeGeneral Electric Company
InventorsMilton D. Bloomer, John D. Harnden, Jr., Denise A. Deallenbach
Life of this patent
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Abstract
Highly linearized and interchangeable networks, each having at least one non-linear resistive element for sensing the magnitude of a physical parameter, such as a thermistor for measuring temperature, have a specified network resistance at a particular value of sensed parameter within a desired sensed parameter range, and also have a predetermined resistance-versus-sensed-parameter slope. The network includes at least one fixed resistor for each resistive sensing element.
Claims11
Apparatus containing only electrically passive elements and having an electrical parameter which is a selected one of terminal conductance and terminal resistance, said electrical parameter having a magnitude substantially linearly related to the magnitude of a sensed parameter, comprising:
- N sensing means, where N is an integer greater than zero, for providing, between first and second terminals thereof, an electrical resistance of magnitude non-linearly related to the magnitude of the sensed parameter;
- first and second network terminals;
- and
- a plurality (N+2) of fixed value electrical resistance elements;
- said plurality of resistance elements including N electrical resistance elements of fixed value, each of the fixed resistance elements electrically series connected to the first terminal of an associated one of said N sensing means to form a like number N of branch circuits;
- all of said N branch circuits being connected in electrical parallel;
- said first network terminal being connected to the paralleled second terminals of all of said N sensing means;
- the (N+1)-st fixed value resistance element being connected in electrical parallel with all of the N paralleled branch circuits;
- and
- the (N+2)-nd fixed value resistance element being connected in electrical series between said second network terminal and the junction between said (N+1)-st fixed value resistance element and all of said N branch circuits;
- the fixed resistance value of each of said (N+2) resistance elements being simultaneously selected to provide, between said first and second network terminals, both a desired value of said electrical parameter for a preselected value of sensed parameter, and also a substantially linear desired value of the rate of change of the magnitude of the electrical parameter for a linear change in the magnitude of said sensed parameter.
Apparatus having an electrical parameter which is a selected one of terminal conductance and terminal resistance, said selected terminal having a magnitude substantially linearly related to the magnitude of a sensed parameter, comprising:
- a single sensing means for providing, between first and second terminals thereof, an electrical resistance of magnitude non-linearly related to the magnitude of the sensed parameter;
- the single sensing means having a first resistance R.sub.x (P.sub.M) at a sensed parameter value P.sub.M in the middle of a desired sensed parameter range and having a second resistance value R.sub.x (P.sub.H) at a highest parameter value P.sub.H in the range;
- a single electrical resistance element in electrical series connection to the first terminal of the sensing means and having a fixed resistance value R.sub.1 given by
- R.sub.1 =R.sub.x (P.sub.M)((P.sub.M)(b-2P.sub.M)-R.sub.A ;
- a first network terminal connected to the second terminal of the sensing means;
- a second network terminal;
- a first fixed magnitude resistance element connected in electrical parallel with the series-connected sensing means and series resistance element and having a resistance value R.sub.A given by
- R.sub.A =(-4mP.sub.M.sup.2 bR.sub.x (P.sub.M)/(b+2P.sub.M).sup.2).sup.1/2
- where m is the preselected slope of the desired substantially linear resistance change with change in measured parameter appearing between said first and second terminal means and b is a material property constant given by
- b=(1/P.sub.M -1/P.sub.H).sup.-1 ln (R.sub.x (P.sub.M)/R.sub.x (P.sub.H));
- and
- a second fixed magnitude resistance element connected in electrical series between the second network terminal and the junction between the fixed magnitude resistance element and the series-connected sensing means and resistance element and having a resistance value R.sub.B given by
- R.sub.B =R.sub.x (P.sub.M)-((R.sub.A R.sub.x (P.sub.M)+R.sub.1 R.sub.A)/(R.sub.1 +R.sub.X (P.sub.M)/R.sub.A)).
A method for providing a network having an electrical parameter which is a selected one of a terminal conductance and terminal resistance, said selected parameter having a magnitude substantially linearly related to the magnitude of a sensed parameter, comprising the steps of:
- (a) providing at least one sensing means having a pair of terminals with an electrical resistance therebetween having a magnitude non-linearly related to the magnitude of the sensed parameter;
- each sensing means having a known resistance at a known value of sensed parameters and a known material property constant;
- (b) connecting a resistance of fixed magnitude in electrical series with each of said at least one sensing means to form a like number of branch circuits;
- (c) providing first and second network terminals;
- (d) connecting a first resistance element of fixed magnitude in electrical parallel connection with all of said branch circuits;
- (e) connecting a first lead of each of said paralleled branch circuits and said first resistance element to said first network terminal;
- (f) connecting a second resistance element of fixed magnitude in series with the paralleled first resistance element and branch circuit combination;
- (g) connecting the remaining end of said second resistance element to said second network terminal;
- and
- (h) adjusting the magnitude of said series, first and second resistance elements to simultaneously provide a desired value of said selected electrical parameter between said first and second network terminals, and a desired, substantially linear value of slope of said selected electrical parameter between the first and second network terminals for a linear change in the magnitude of the sensed parameter.
Dependencies are inferred from the claim text.