Linear position transducer and signal processor
First Claim
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1. A linear position measurement apparatus including a transducer comprising:
- (a) a tube of electrically insulating material having a length at least substantially four times its outside diameter;
(b) a helical, conducting coil wound around the tube and at least substantially four of said diameters long;
(c) an elongated core of electrically conducting, non-ferromagnetic material matingly received within and slidable in axial reciprocation within the tube; and
(d) a non-conductive, ferromagnetic, tubular layer surrounding the coil and at least substantially four of said diameters long, said layer having substantially uniform radial dimensions along its length.
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Abstract
Disclosed are a transducer for converting linear motion of a core into a proportional change in inductance by means of skin effect, and bridge processing circuitry for stable conversion of changing inductance into a proportional voltage.
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Citations
15 Claims
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1. A linear position measurement apparatus including a transducer comprising:
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(a) a tube of electrically insulating material having a length at least substantially four times its outside diameter; (b) a helical, conducting coil wound around the tube and at least substantially four of said diameters long; (c) an elongated core of electrically conducting, non-ferromagnetic material matingly received within and slidable in axial reciprocation within the tube; and (d) a non-conductive, ferromagnetic, tubular layer surrounding the coil and at least substantially four of said diameters long, said layer having substantially uniform radial dimensions along its length. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A linear position measurement apparatus comprising:
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(a) a tube of electrically insulating material having a length at least substantially four times its outside diameter; (b) a helical conductor coil having a skin depth dependent upon frequency and wound around the tube and at least substantially four of said diameters long, said coil being substantially a single layer of windings having a uniform conductor spacing along its length and a radial thickness not greater than substantially the skin depth of the coil conductor at a selected operating frequency; (c) an elongated core of electrically conducting, non-ferromagnetic material matingly received within and slidable in axial reciprocation within the tube; (d) a non-conductive, ferromagnetic, tubular layer surrounding the coil and at least substantially four of said diameters long, said layer having substantially uniform radial dimensions along its length; and (e) a tubular, electrically conductive, ferromagnetic shield surrounding said ferromagnetic layer along essentially the entire length of the coil.
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Specification