Compensation of second-order non-linearity in sensors employing double-ended tuning forks

A double-ended tuning fork (DETF) sensor, comprising;

• a first and a second DETF, each of said DFTFs having a first end and a second end;
• a proof mass;
• a support frame;
• at least one hinge rotatably connecting said proof mass to said support frame;
• said first ends of said DETFs spaced apart and connected to said proof mass and said second ends of said DETFs connected to said support frame;
• and
• wherein said first DETF and said second DETF are constructed such that a first second-order non-linearity term associated with said first DETF and a second second-order non-linearity term associated with said second DETF are substantially equal in magnitude wherein a rotation center of said hinge defines a hinge axis, and wherein said first ends of said DETFs are spaced substantially equidistantly from said hinge axis.

A double-ended tuning fork (DETF) sensor, comprising:

• a first and a second DETF, each of said DETFs having a first end and a second end;
• a proof mass;
• a support frame;
• at least one hinge rotatably connecting said proof mass to said support frame;
• said hinge having a rotation center defining a hinge axis having a first side and a second side,
• said proof mass positioned on said first side of said hinge axis and formed with a relief having two essentially parallel and spaced apart interior surfaces, said relief located adjacent said hinge,
• said support frame including a projection having two essentially parallel exterior surfaces coincident with and spaced apart from said interior surfaces of said relief,
• said hinge comprising a first and a second flexure, said flexures flanking said projection,
• said first end of said first DETF connected to a first interior surface of said relief and said second end of said first DETF connected to a first of said exterior surface of said projection;
• said first end of said second DETF connected to a second interior surface of said relief and said second end of said second DETF connected to a second of said exterior surface of said projection;
• whereby a deflection of said proof mass puts one of said first or second DETFs in compression and puts the other of said DETFs in tension;
• and
• wherein said first DETF and said second DETF are constructed such that a first second-order non-linearity term associated with said first DETF and a second second-order non-linearity term associated with said second DETF are substantially equal in magnitude.

A double-ended tuning fork (DETF) sensor, comprising:

• a first and a second DETF, each of said DETFs having a first end and a second end;
• a proof mass;
• a support frame;
• at least one hinge rotatably connecting said proof mass to said support frame, said hinge having a center of rotation defining a hinge axis;
• said first end of said first DETF positioned on a first side of said hinge axis and spaced away from said hinge axis by a first predetermined distance;
• said first end of said second DETF positioned on a second side of said hinge axis and spaced away from said hinge axis by a second predetermined distance;
• a first second-order non-linearity term associated with said first DETF;
• and
• a second second-order non-linearity term associated with said second DETF which is substantially equal to said first second-order non-linearity term.