Abstract: 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.

Abstract: A preamplifier portion 2 is arranged between a head portion 1 containing a detecting coil and an amplifier portion 3, wherein a detecting circuit and a controlling circuit and the like are arranged. The preamplifier portion 2 is connected to the head portion 1 via a shielded cable 5 of fixed length, while connected to the amplifier portion 3 via multi core cables 6a and 6b having connectors 7a and 7b. In the preamplifier portion 2, in addition to an oscillating circuit, an EEPROM containing a compensating table for compensating the relation between the oscillation output of the oscillating circuit and a detected distance is arranged. This EEPROM is connected to the controlling circuit at the side of the amplifier portion 3.

Abstract: 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.

Abstract: A source table showing a standard relation between a detection object and a detection distance is stored in a memory (4). A CPU (3) receives inputs regarding distances to three measurement points from an input portion (5) and recognizes an amplitude voltage corresponding to the input, as a measured value at the measurement point. Furthermore, the CPU (3) extracts a range which corresponds to a difference between the farthest distance and the shortest distance, in which a ratio between voltages corresponding to measurement points closely resembles a ratio between the actually measured values, from the source table as a usage range, and creates a conversion table by correcting voltages in this extracted range.

Abstract: A source table showing a standard relation between a detection object and a detection distance is stored in a memory (4). A CPU (3) receives inputs regarding distances to three measurement points from an input portion (5) and recognizes an amplitude voltage corresponding to the input, as a measured value at the measurement point. Furthermore, the CPU (3) extracts a range which corresponds to a difference between the farthest distance and the shortest distance, in which a ratio between voltages corresponding to measurement points closely resembles a ratio between the actually measured values, from the source table as a usage range, and creates a conversion table by correcting voltages in this extracted range.

Abstract: A preamplifier portion 2 is arranged between a head portion 1 containing a detecting coil and an amplifier portion 3. wherein a detecting circuit and a controlling circuit and the like are arranged. The preamplifier portion 2 is connected to the head portion 1 via a shielded cable 5 of fixed length, while connected to the amplifier portion 3 via multi core cables 6a and 6b having connectors 7a and 7b. In the preamplifier portion 2, in addition to an oscillating circuit, an EEPROM containing a compensating table for compensating the relation between the oscillation output of the oscillating circuit and a detected distance is arranged. This EEPROM is connected to the controlling circuit at the side of the amplifier portion 3.