STRAIN-GAGE TRANSDUCER BRIDGE GAGES WITH INTEGRAL CALIBRATION RESISTORS

摘要

ABSTRACT OF THE DISCLOSUREEach of two pairs of electrical-resistance strain gageswhich are to make up a measurement bridge for a beam-type loadcell is fashioned as a composite wherein two spaced-apart gridsof foil-type parallel elongated filaments oriented and function-ing as strain gages are made of material promoting a strain gagefactor effective to compensate for elastic modulus change of thebeam material as temperature varies over an expected range. In-termediate the two grids of strain-gage filaments, where a neutralposition between tension and compression surface strains of thesensing element of a gaged beam may be expected to appear, thecommon insulating backing for the two grids carries a set of nar-row strands which produce a dummy foil resistance of predeter-mined value needed for a calibration wherein it simulates theinfluence upon bridge input impedance of a temperature-compensation resistance such as would otherwise be used withoutthe inherent compensation for elastic modulus changes by way ofoffsetting effects of strain gage factor of the gages. The samematerial which forms the foil or printed-circuit type gage gridsalso forms the dummy or calibration resistor upon the same under-lying backing, and, in addition creates relatively large-area andlow-resistance integral interconnections between the gages andresistance and tabs for needed external-wiring connections.