Capacitor and pressure transducer

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

• a first capacitance base member and a second capacitance base member respectively having capacitor surfaces normally arranged in parallel planes, said second capacitance base member having spaced apart capacitor surfaces located on opposite sides relative to a longitudinal displacement axis where said spaced apart capacitance surfaces on said second capacitance base member and said capacitor surface on said first capacitance base member respectively define first and second capacitors;
• torsion beam means disposed along said displacement axis;
• means for attaching said torsion beam means to said second capacitance base member relative to said spaced apart capacitor surfaces and said first capacitance base member so that a torsion force on said torsion beam means can develop an angular torque displacement of said second capacitance base member about said displacement axis relative to said first capacitance base member and produce a dependent capacitance change in said first and second capacitors;
• and
• force means coupled to said torsion beam means for producing said torsion force on said torsion beam means about said displacement axis and for developing angular torque displacement of said second capacitance base member relative to said first capacitance base member and a capacitance change in said first and second capacitors as a function of said torsion force.

A method of measuring capacitance in a dual capacitor device utilizing dependent capacitors for measurement purposes and wherein the capacitor device has a first capacitance base member and a second capacitance base member respectively having capacitor surfaces arranged in parallel planes and defining first and second capacitors, said first and second capacitors being located relative to a central plane transverse to said parallel planes and said first and second capacitors have first and second capacitance gaps, said capacitor device having a torsion beam means and attaching means arranged for permitting angular torque displacement of the capacitor surfaces on said second capacitance base member relative to the capacitor surfaces on said first capacitance base member;

• the method comprising the steps of:
• obtaining a torque force by subjecting a bourdon tube wound in a coil about a coil axis to a fluid pressure where one end of the bourdon tube is fixed relative to said first capacitance base member and the other end of said bourdon tube is attached to said torsion beam means on said second capacitance base member;
• torquing the torsion beam means coupled to said second capacitance base member with the torque force about a displacement axis located in said central plane for angularly torquing said second capacitance base member about said displacement axis so that angular torque displacement of said second capacitance base member about said displacement axis produces a dependent change in said capacitance gaps of said first and second capacitors.

A method of measuring capacitance in a dual capacitor device utilizing dependent capacitances for measurement purposes and wherein the capacitor device has a first capacitance 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 capacitor 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 capacitance base member and an outer section connected by a metal torsion beam means to said central section so that said second capacitance base member can be angularly torqued relative to said first capacitance base member, 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 bourdon tube wound in a coil about a coil axis, 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 capacitance base member relative to said first capacitance base member about said displacement axis by applying a fluid pressure to said bourdon tube and developing a torque force about said displacement axis and developing an angular torque displacement of said outer section of second base member about said displacement axis relative to said first capacitance base member and in response to pressure thereby 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.