Linear ECL distance measuring gauge
First Claim
1. In an eddy current loss proximity distance measuring gauge comprising an eddy current loss oscillator including a feedback voltage controlling tuned circuit including a coil whose Q is varied when a magnetic target is brought into the magnetic field generated by said coil, said Q variation creating a change in the amplitude of the oscillations produced by said eddy current loss oscillator, the improvement comprising a linearizing circuit connected to said eddy current loss oscillator so as to sense the amplitude of the oscillations created by said eddy current loss oscillator and control, in a linear manner, the relationship between the amplitude of said oscillations and the distance between said coil and said metallic target.
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Abstract
A linear eddy current loss (ECL) proximity distance measuring gauge comprising an ECL oscillator and a linearizing DC feedback circuit is disclosed. As the distance between a magnetic target and the ECL coil increases and changes the impedance of the ECL tuned circuit, the linearizing DC feedback circuit shunts current away from the tuned circuit and controls the rate at which oscillation amplitude varies with a change in target distance. The amplitude control created by the linearizing DC feedback circuit results in oscillation amplitude being linearly related to the distance between the target and the ECL coil. A peak detector circuit detects oscillation amplitude and applies a directly related DC voltage to a buffering emitter follower output circuit. Thus, output voltage is linearly related to target distance.
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Citations
16 Claims
- 1. In an eddy current loss proximity distance measuring gauge comprising an eddy current loss oscillator including a feedback voltage controlling tuned circuit including a coil whose Q is varied when a magnetic target is brought into the magnetic field generated by said coil, said Q variation creating a change in the amplitude of the oscillations produced by said eddy current loss oscillator, the improvement comprising a linearizing circuit connected to said eddy current loss oscillator so as to sense the amplitude of the oscillations created by said eddy current loss oscillator and control, in a linear manner, the relationship between the amplitude of said oscillations and the distance between said coil and said metallic target.
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4. A linear eddy current loss proximity distance measuring gauge comprising:
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A. an eddy current loss oscillator including; 1. an electronic amplification means; 2. a feedback circuit connected to feed back a portion of the output of said electronic amplification means to the input thereof in a manner such that a feedback oscillator is formed by said electronic amplification means and said feedback circuit, said feedback circuit including a tuned circuit including a coil forming an eddy current loss proximity sensor element, said tuned circuit connected in a manner such that it controls the voltage fed back to the input of said electronic amplification means and, thus, the amplitude of the oscillations generated by said feedback oscillator; and
,B. a linearizing circuit including; 1. a detector for detecting the amplitude of the oscillations of said eddy current loss oscillator; and
,2. a linearizing DC feedback circuit connected to said feedback oscillator and to said detector so as to shunt a portion of said current flow in said feedback circuit away from said tuned circuit in accordance with the amplitude of the oscillations detected by said detector. - View Dependent Claims (5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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Specification