A system for sensing a position of a locking bolt of an industrial locking switch includes an inductive circuit, a converter, and a master controller. The inductive circuit includes an inductive coil and a capacitor electrically connected in parallel. The inductive coil is positioned to receive a locking bolt of an industrial locking switch when the locking bolt is transitioned to a lock position. The converter is configured to convert a frequency of a current signal on the inductive circuit to a digital frequency value. The master controller is configured to generate a bolt detection signal in response to determining that the digital frequency value changes by an amount equal to or substantially equal to a defined frequency shift corresponding to a frequency shift induced by the inductive coil in response to presence of the locking bolt within the inductive coil's magnetic field.

A proximity sensor that detects the distance between two coils is disclosed. In one example, the proximity sensor includes a reference signal generation circuit, a first coil, a second coil, a clock signal generation circuit, and a switched capacitor circuit. The reference signal generation circuit applies a first alternating voltage to the first coil and transmits a reference signal synchronized with the first alternating voltage to the clock signal generation circuit. The second coil is coupled with the first coil by magnetic field coupling to generate a second alternating voltage correlated with a coupling coefficient. The clock signal generation circuit transmits clock signals corresponding to the reference signal to the switched capacitor circuit, and the switched capacitor circuit detects a distance between the first coil and the second coil by acquiring the second alternating voltage at a timing when each of the clock signals changes.

A proximity sensor that detects the distance between two coils is disclosed. In one example, the proximity sensor includes a reference signal generation circuit, a first coil, a second coil, a clock signal generation circuit, and a switched capacitor circuit. The reference signal generation circuit applies a first alternating voltage to the first coil and transmits a reference signal synchronized with the first alternating voltage to the clock signal generation circuit. The second coil is coupled with the first coil by magnetic field coupling to generate a second alternating voltage correlated with a coupling coefficient. The clock signal generation circuit transmits clock signals corresponding to the reference signal to the switched capacitor circuit, and the switched capacitor circuit detects a distance between the first coil and the second coil by acquiring the second alternating voltage at a timing when each of the clock signals changes.

A system may include a resonant phase sensing system comprising a resistive-inductive-capacitive sensor and a measurement circuit communicatively coupled to the resistive-inductive-capacitive sensor, and a compensation circuit. The measurement circuit may be configured to use a phase detector to measure phase information associated with the resistive-inductive-capacitive sensor and based on the phase information, determine a displacement of a metal plate relative to the resistive-inductive-capacitive sensor. The compensation circuit may be configured to detect a change in a physical property associated with the resistive-inductive-capacitive sensor other than the displacement and compensate the phase information to correct for the change in the physical property.

A system for sensing a position of a locking bolt of an industrial locking switch includes an inductive circuit, a converter, and a master controller. The inductive circuit includes an inductive coil and a capacitor electrically connected in parallel. The inductive coil is positioned to receive a locking bolt of an industrial locking switch when the locking bolt is transitioned to a lock position. The converter is configured to convert a frequency of a current signal on the inductive circuit to a digital frequency value. The master controller is configured to generate a bolt detection signal in response to determining that the digital frequency value changes by an amount equal to or substantially equal to a defined frequency shift corresponding to a frequency shift induced by the inductive coil in response to presence of the locking bolt within the inductive coil's magnetic field.

An industrial locking switch includes an inductive sensing circuit that uses a non-contact technique to detect when the switch's locking bolt has transitioned to the lock position. The inductive sensing circuit can comprise an inductive coil, a capacitor, and a converter that converts a frequency of a current signal through the inductive coil to a digital frequency value. A controller detects when the locking bolt has advanced to the lock position by monitoring the digital frequency value for frequency shifts indicative of a disturbance of the induction coil's magnetic field by the locking bolt. To validate operation of the inductive sensing system without requiring actuation of the locking bolt, a diagnostic switch connects a diagnostic capacitor to the inductive circuit to simulate the frequency shift caused by the locking bolt, and the inductive sensing system is validated if the expected frequency shift is detected.

A proximity sensor and a method of changing a detection distance are provided to suppress changes in a consumption current of an oscillation circuit. The proximity sensor includes an oscillation circuit having an oscillation amplitude that changes with a feedback current, a comparing part comparing the oscillation amplitude with a threshold, a detecting part detecting a target object based on a comparison result of the comparing part, a voltage value signal generating part generating a voltage value signal based on the feedback current and the detection distance, a threshold setting part setting an analog signal converted from the voltage value signal as the threshold, a current value signal generating part generating a current value signal based on the detection distance and the voltage value signal, and a current value setting part setting an analog signal converted from the current value signal as a current value of the feedback current.

A system may include a resonant phase sensing system comprising a resistive-inductive-capacitive sensor and a measurement circuit communicatively coupled to the resistive-inductive-capacitive sensor, and a compensation circuit. The measurement circuit may be configured to use a phase detector to measure phase information associated with the resistive-inductive-capacitive sensor and based on the phase information, determine a displacement of a metal plate relative to the resistive-inductive-capacitive sensor. The compensation circuit may be configured to detect a change in a physical property associated with the resistive-inductive-capacitive sensor other than the displacement and compensate the phase information to correct for the change in the physical property.

A proximity sensor and a method of changing a detection distance are provided to suppress changes in a consumption current of an oscillation circuit. The proximity sensor includes an oscillation circuit having an oscillation amplitude that changes with a feedback current, a comparing part comparing the oscillation amplitude with a threshold, a detecting part detecting a target object based on a comparison result of the comparing part, a voltage value signal generating part generating a voltage value signal based on the feedback current and the detection distance, a threshold setting part setting an analog signal converted from the voltage value signal as the threshold, a current value signal generating part generating a current value signal based on the detection distance and the voltage value signal, and a current value setting part setting an analog signal converted from the current value signal as a current value of the feedback current.