Inductive proximity sensor using coil time constant for temperature compensation

A method for determining coil temperature in a proximity sensor with minimal current consumption, comprising;

• determining a gamma value for the resonant circuit such that
• γ=e−(R2/2L1)Δt
• where R2 is a resistor in the resonant circuit and L1 is an inductor in the resonant circuit;
• and Δt is the time difference between voltage measurements and
• determining a temperature of a sensor coil in the proximity sensor based at least in part on the gamma value.

A method for determining temperature in a sensor coil in an oscillator circuit of an inductive proximity sensor, comprising:

• measuring a first tank voltage in the oscillator circuit;
• quenching the oscillator circuit to induce a period of oscillatory voltage decay;
• measuring a second tank voltage after a predetermined time period;
• and
• dividing the second tank voltage by the first tank voltage to determine a gamma value.

A system that facilitates a determination of temperature of a sensor coil in an extended range proximity sensor, comprising:

• means for determining a time constant value for a resonant damping circuit in the proximity sensor;
• means for determining a total circuit inductance L1;
• and
• means for determining a temperature of the sensor coil based at least in part on the time constant value and the inductance of the resonant damping circuit.