Temperature compensation for condition response of a condition-responsive network

Claim 1

CONDITION-RESPONSIVE APPARATUS HAVING A DESIRED RELATION BETWEEN THE TEMPERATURE AT A GIVEN LOCATION AND THE RESPONSE OF AN ELECTRICAL NETWORK TO A CONDITION TO BE MEASURED COMPRISING, IN COMBINATION, AN ELECTRICAL NETWORK INCLUDING AT LEAST ONE ELECTRICAL IMPEDANCE ELEMENT WHOSE IMPEDANCE VARIES IN ACCORDANCE WITH THE VARIATION OF THE CONDITION TO BE MEASURED, SAID NETWORK HAVING TWO INPUT AND TWO OUTPUT TERMINALS, A SOURCE OF VOLTAGE IMPRESSED UPON SAID INPUT TERMINALS WHEREBY A VARIATION OF SAID CONDITION RESULTS IN A CORRESPONDING VARIATION IN THE VOLTAGE APPEARING ACROSS SAID OUTPUT TERMINALS, TWO TEMPERATURE-SENSITIVE IMPEDANCE ELEMENTS WHICH UNDERGO CHANGE IN ELECTRICAL IMPEDANCE WITH TEMPERATURE, SAID ELECTRICAL IMPEDANCE ELEMENTS BEING CONNECTED TO SAID NETWORK SO THAT SAID CHANGE IN IMPEDANCE EFFECTS A CORRESPONDING CHANGE IN SAID RESPONSE OF THE ELECTRICAL NETWORK TO A CONDITION TO BE MEASURED, EACH OF SAID TEMPERATURE-SENSITIVE ELEMENTS BEING SO LOCATED AS TO EXPERIENCE SUBSTANTIALLY THE TEMPERATURE AT SAID GIVEN LOCATION AND HAVING THEIR CHANGES IN IMPEDANCE WITH TEMPERATURE PREDETERMINED TO BE IN EXCESS OF THOSE REQUIRED FOR OBTAINING SAID DESIRED RELATION, TWO SUBSTANTIALLY CONSTANT IMPEDANCE ELEMENTS AND MEANS CONNECTING EACH OF SAID SUBSTANTIALLY CONSTANT IMPEDANCE ELEMENTS IN PARALLEL WITH A DIFFERENT ONE OF SAID TEMPERATURE-SENSITIVE ELEMENTS AS A SHUNT, SAID SHUNTS BEING OF SUCH IMPEDANCE VALUES AS TO REDUCE THE EXTENT BY WHICH THE PREDETERMINED CHANGES IN IMPEDANCE OF SAID TEMPERATURE-SENSITIVE ELEMENTS EFFECT SAID CORRESPONDING CHANGE IN SAID NETWORK RESPONSE TO OBTAIN SAID DESIRED RELATION, AND FURTHER CHARACTERIZED IN THAT SAID NETWORK COMPRISES A BRIDGE CIRCUIT, SAID TWO TEMPERATURE-SENSITIVE IMPEDANCE ELEMENTS ARE CONNECTED IN SERIES WITH EACH OTHER AND WITH THE SOURCE OF VOLTAGE AND THE INPUT TERMINALS OF THE NETWORK, SAID NETWORK THEREBY BEING CONNECTED INTERPOSED BETWEEN SAID TWO TEMPERATURE-SENSITIVE ELEMENTS HAVING THE TWO SHUNTS CONNECTED THEREWITH SO THAT THE RELATIVE CONTRIBUTIONS OF THE TWO TEMPERATURE-SENSITIVE ELEMENTS TO THE REDUCTION OF SAID EXTENT CAN BE ESTABLISHED SEPARATELY AS DESIRED, AND A SUBSTANTIALLY CONSTANT IMPEDANCE CALIBRATION ELEMENT IS PROVIDED TOGETHER WITH MEANS FOR TEMPORARILY CONNECTING IT ACROSS ONE OF SAID OUTPUT TERMINALS AND ONE TERMINAL OF SAID SOURCE OF VOLTAGE SO AS TO PROVIDE PURELY ELECTRICAL MEANS OF PRODUCING A NETWORK OUTPUT WHICH CAN BE CALIBRATED IN TERMS OF SAID CONDITION TO BE MEASURED, SAID CALIBRATION ELEMENT BEING THEREBY CONNECTED IN PARALLEL WITH THE COMBINATION OF ONE ARM OF SAID BRIDGE CIRCUIT AND ONE OF SAID TEMPERATURE-SENSITIVE IMPEDANCE ELEMENTS TAKEN IN SERIES, WHEREBY THE EFFECT OF TEMPERATURE UPON THE OUTPUT PRODUCED BY OPERATION OF SAID CALIBRATION ELEMENT CAN BE VARIED BY SELECTING THE IMPEDANCE OF SAID SUBSTANTIALLY CONSTANT IMPEDANCE ELEMENT SHUNTING SAID LAST-NAMED TEMPERATURE-SENSITIVE ELEMENT SO THAT THE NETWORK OUTPUT PRODUCED BY SAID ELECTRICAL MEANS CAN BE MADE SUBSTANTIALLY INDEPENDENT OF TEMPERATURE WHILE THE NET CONTRIBUTION OF BOTH TEMPERATURE-SENSITIVE ELEMENTS TO THE REDUCTION OF SAID EXTENT CAN BE ESTABLISHED TO OBTAIN SAID DESIRED RELATION BY SELECTING THE IMPEDANCE OF SAID SUBSTANTIALLY CONSTANT IMPEDANCE ELEMENT SHUNTING THE REMAINING TEMPERATURE-SENSITIVE ELEMENT.