Capacitive inclination and acceleration sensor
AssigneeSigma-Delta N.V.
InventorsRudi De Winter, Roger Diels
Life of this patent
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Abstract
A capacitive position sensor employs conventional printed circuit board (PCB) technology to detect capacitive changes caused by the movement of a ball along conductive tracks. A recessed region (or through hole) is stamped on the PCB with well controlled dimensions. Electrically conductive tracks are laid around the region and connect to a capacitance detection circuit on the PCB. As the PCB experiences inclination or acceleration the ball moves along the axis of the recessed region causing variations in the measured capacitance.
Claims14
A position sensor comprising:
- a printed circuit board (PCB) having an elongated aperture stamped therethrough, a first terminal of electrically conductive track disposed on a surface of said PCB along a first side of said elongated aperture, and a second terminal of electrically conductive track disposed on said surface of said PCB along a second side of said elongated aperture;
- a ball rollably disposed in said elongated aperture;
- and
- a capacitance detection circuit coupled to said first and second terminals for detecting a change in the capacitance between said first and second terminals, as said ball rolls along said elongated aperture.
A position sensor comprising:
- a printed circuit board having an elongated aperture stamped therethrough, said printed circuit board further comprising:
- a first terminal of an electrically conductive track disposed at an edge on a first side of said elongated aperture,
- a second terminal of an electrically conductive track disposed at an edge on a second side of said elongated aperture, and
- a third terminal of art electrically conductive track disposed at an edge on said second side of said elongated aperture;
- a ball rollably disposed in, and supported by edges of said elongated aperture;
- and
- a capacitance detection circuit coupled to said first, second and third terminals for measuring a change in the capacitance between said first and second terminals and said first and third terminals, as said ball rolls along the edges of said walls of said elongated recessed region, said capacitance detection circuit comprising:
- an integrator coupled to said first terminal;
- an analog to digital converter coupled to an output of said integrator;
- and
- a sequencer coupled to said second and third terminals and said integrator and said analog to digital converter.
A method for sensing the position of an object comprising the steps of:
- (a) providing the object with a printed circuit board;
- (b) stamping an elongated aperture through said printed circuit board;
- (c) disposing first and second electrically conductive tracks on either sides of said elongated aperture, respectively;
- (d) placing an electrically conductive ball on said elongated aperture such that said ball rolls along a longitudinal axis of said aperture supported by sidewalls of said aperture;
- and
- (e) detecting variations in capacitance between said first and second electrically conductive tracks as said ball rolls along said elongated aperture.
Dependencies are inferred from the claim text.