Capacitance pressure transducer

A dual capacitor device for utilizing dependent capacitances for measurement purposes comprising:

• a first capacitor base member and a second capacitance base member arranged with parallel capacitor surfaces in parallel planes where facing parallel capacitor surfaces are located on opposite sides relative to a transverse central plane and where said facing capacitance surfaces respectively define first and second capacitors;
• said second capacitor base member having a displacement axis disposed in said central plane and disposed parallel to said parallel planes;
• torsion beam means disposed along said displacement axis and attached to said second capacitor base member so that angular displacement of said second capacitor base member about said displacement axis produces a capacitance change in said first and second capacitors;
• and
• force means coupled to said torsion means for producing a torsion force on said torsion beam means for developing angular displacement of said second capacitor base member and a capacitance change in said capacitors as a function of said torsion force;
• said force means including a torque member aligned with said displacement axis and having a transverse portion providing a moment arm and including a bellows acting on said moment arm for providing said torsion force.

A method of measuring capacitance in a dual capacitor device utilizing dependent capacitances for measurement purposes and wherein the capacitor device has a first capacitor base member and a second capacitance base member arranged with parallel capacitor surfaces in parallel planes where said parallel capacitor surfaces are located on opposite sides relative to a central transverse plane and said capacitance surfaces define first and second capacitors having first and second capacitance gaps and wherein the second capacitance base member has a central section attached to said first capacitor base member and an outer section connected by torsion beam means to said central section, and wherein said torsion beam means is disposed along a displacement axis in said central plane with the torsion beam means being coupled to a torque member aligned with said displacement axis and having a transverse moment arm acted upon by a bellows, and wherein said capacitor surfaces on said second capacitance base member are located on said outer section, comprising the steps of:

• torquing said outer section of said second capacitor base member about said displacement axis located in said torsion beam means by applying a fluid pressure to said bellows for developing a torque force about said displacement axis and developing an angular displacement of said outer section of second base member about said displacement axis in response to pressure for producing a dependent change in said capacitance gaps of said first and second capacitors;
• and
• maintaining the torque force below the yield point of the torsion beam means to minimize permanent distortion in said torsion beam means.