Wheatstone bridge-type transducers with reduced thermal shift

In a method of making a Wheatstone bridge-type transducer having a housing, the improvement of reducing thermal shift, comprising in combination the steps of:

• providing a diaphragm of semiconductor material accepting formation of strain gages therein having a uniform temperature coefficient of resistance therethrough;
• providing in said diaphragm strain gages with an initial zero offset and thermal zero shift requiring only a shunt balance for compensation;
• and
• compensating zero offset and thermal zero shift of said strain gages with only said shunt balance.

In a method of making a Wheatstone bridge-type transducer having a housing, the improvement of reducing thermal shift, comprising in combination the steps of:

• providing a diaphragm of semiconductor material accepting formation of strain gages therein having a uniform temperature coefficient of resistance therethrough;
• providing in said diaphragm strain gages with an initial zero offset and thermal zero shift requiring only a series balance for compensation;
• and
• compensating thermal zero shift of said strain gages with only said series balance.

In a Wheatstone bridge type transducer having a housing, the improvement of reducing thermal shift, comprising in combination:

• a diaphragm of semiconductor material having strain gages therein and a uniform temperature coefficient of resistance therethrough, said strain gages requiring a predetermined amount of unbalance for balancing a zero offset of said strain gages, and one of said strain gages having a series balance equal to one-half of said predetermined amount;
• a support for said diaphragm, subject to mechanical strains;
• means for isolating said diaphragm from said mechanical strains to which said support is subject, including a cushion of compliant material between said diaphragm and said support for supporting said diaphragm in said housing, while leaving said strain gages exposed to strains imposed by a physical parameter to be measured with said transducer;
• electric lead wires for said strain gages having sufficient limpness to prevent transmission of mechanical strains therealong;
• and
• means for completing balancing of said zero offset while also avoiding a thermal zero shift of the Wheatstone bridge, including a shunt balance equivalent to one-half of said predetermined amount, in an adjacent one of said strain gages.

In a method of making a Wheatstone bridge-type transducer having a housing, the improvement of reducing thermal shift, comprising in combination the steps of:

• providing a diaphragm of semiconductor material accepting formation of strain gages therein having a uniform temperature coefficient of resistance therethrough;
• providing in said diaphragm strain gages and determining an amount of unbalance required for balancing a zero offset of said strain gages;
• supporting said diaphragm in a mechanically floating condition in said housing;
• providing one of said strain gages with a series balance equal to one-half of said determined amount;
• and
• completing balancing of said zero offset and avoiding also a thermal zero shift of said bridge by providing an adjacent one of said strain gages with a shunt balance equivalent to one-half of said determined amount.

In a Wheatstone bridge-type transducer having a housing, the improvement of reducing thermal shift, comprising in combination:

• a diaphragm of semiconductor material having strain gages therein and a uniform temperature coefficient of resistance therethrough, said strain gages requiring a predetermined amount of unbalance for balancing a zero offset of said strain gages;
• means for supporting said diaphragm in a mechanically floating condition in said housing;
• a series balance equal to one-half of said predetermined amount for one of said strain gages;
• and
• means for completing balancing of said zero offset while also avoiding a thermal zero shift of the Wheatstone bridge, including a shunt balance equivalent to one-half of said predetermined amount connected to an adjacent one of said strain gages.