Wheatstone bridge-type transducers with reduced thermal shift

Abstract

Thermal shift in Wheatstone bridge-type transducers is reduced by providing a diaphragm of semiconductor material accepting formation of strain gages therein having a uniform temperature coefficient of resistance therethrough. That diaphragm is supported in a mechanically floating condition, such as by interposing a cushion of compliant material between the diaphragm and a support which is subject to mechanical strains. An amount of unbalance required for balancing the strain gages on the diaphragm is determined. One of these strain gages is provided with a series balance equal to one-half of that determined amount, while an adjacent one of the strain gages is provided with a shunt balance equivalent to one-half of that determined amount. Alternatively, the strain gages are provided with an initial thermal zero shift offset requiring only a shunt balance for compensation, and thermal zero shift is then compensated only with that shunt balance, or the strain gages are provided with an initial thermal zero shift offset requiring only a series balance of compensation, and that thermal zero shift is then compensated with only that series balance.