Patent attributes
An operation section 2 is provided to a proximity sensor including: a detection section having an oscillation circuit 10; and an amplification section 2 having a function detecting a metal body using an oscillation amplitude of the oscillation circuit 10. In a set mode, when an operation to set an adjustment value for a sensitivity adjustment (a sensitivity adjustment value) is conducted in an operation section 22, CPU 20 generates a sensitivity adjustment signal in digital quantity indicating the sensitivity adjustment value and outputs the signal to a D/A converter 25. The sensitivity adjustment signal digital-to-analog converted by the D/A converter 25 is given to a feedback circuit 13 through a voltage adjustment circuit 26. Since the feedback circuit 13 is designed so as to change a feedback current quantity according to an applied voltage, a current with a magnitude matching a value the sensitivity adjustment signal is fed back to a resonance circuit 11 to thereby control an oscillation amplitude.
