US 4,068,189 A · Linear oscillator for proximity sensor

Abstract

A linear oscillator circuit has a resonant circuit which develops an oscillating voltage V.sub.R having an amplitude proportional to a distance between a conducting body and the resonant circuit located within a probe. A control power drive circuit coupled to the output of the resonant circuit switches a current through the resonant circuit during each period of oscillation of the voltage V.sub.R. A reference current source is coupled to the control power drive circuit for drawing a current through the control power drive circuit and the resonant circuit. The magnitude of the current is equal to the magnitude of an independently established reference current. A detector circuit responsive to the value of the amplitude of oscillation may be provided to indicate the distance of the conductive body from the resonant circuit-containing probe.

Claims7

Dependent claims

A linear oscillator circuit comprising:

a resonant circuit having an input and an output, the input coupled to a voltage V+, said resonant circuit being capable of developing an oscillating voltage V.sub.R having a peak amplitude which is directly proportional to a distance between the resonant circuit and a conducting body;
a control power drive circuit coupled to the output of the resonant circuit for switching a current through the resonant circuit during each period of oscillation of the voltage V.sub.R ;
a constant current source coupled to said control power drive circuit for drawing the current through said control power drive circuit and said resonant circuit wherein the magnitude of the current is equal to the magnitude of an independently established reference current;
and
a current control circuit coupled to the constant current source for establishing the independently established reference current.

2 more elements

A linear oscillator circuit comprising:

a resonant circuit having an input and an output, the input coupled to a voltage V+, said resonant circuit being capable of developing an oscillating voltage V.sub.R having a peak amplitude which is directly proportional to a distance between the resonant circuit and a conducting body;
an alternate current path having an input and an output, the input coupled to a voltage V+;
a control power drive circuit coupled to the output of the resonant circuit and to the output of the alternate current path for switching a current alternately through the alternate current path and the resonant circuit during each period of oscillation of the voltage V.sub.R ;
a constant current source coupled to said control power drive circuit for providing a current through said control power drive circuit wherein the current is constant irrespective of the voltage V.sub.R and equal to an independently established reference current;
and
a current control circuit coupled to the constant current source for establishing the independently established reference current.

3 more elements

Dependencies are inferred from the claim text.

Linear oscillator for proximity sensor

Life of this patent

Linear oscillator for proximity sensor

Life of this patent

Abstract

Claims7