Inductive proximity sensor for detecting ferromagnetic, non-permeable or magnet targets

A proximity sensor, comprising:

• a core formed of a permeable material, the core having a generally planar top surface, a bottom, a side surface having a depth between the top and the bottom surface of the core, and an outer perimeter bounding the side surface of the core, the core defining a groove which extends into the core from the top surface of the core;
• a sensing coil positioned in the groove of the core;
• and
• an oscillator circuit coupled to the sensing coil for energizing the sensing coil to define a sensing region in relation to the sensing coil, the oscillator circuitry sensing an object in the sensing region based on the output signal of the sensing coil, the core and sensing coil being constructed so as to be operational to detect ferromagnetic, non-permeable or magnetic targets.

A method for detecting the presence of a magnetic object which comprises:

• providing a core formed of a permeable material, the core having a generally planar top surface, a bottom, a side surface having a depth between the top and the bottom surface of the core, and an outer perimeter bounding the side surface of the core, the core defining a groove which extends into the core from the top surface of the core;
• providing at least one sensing coil positioned around the groove of the core;
• and
• measuring the impedance over the sensing coil, and if the impedance varies greater than a predetermined value, generating a signal to indicate the presence of the magnetic object.

A method for detecting the presence of a ferromagnetic object which comprises:

• providing a core formed of a permeable material, the core having a generally planar top surface, a bottom, a side surface having a depth between the top and the bottom surface of the core, and an outer perimeter bounding the side surface of the core, the core defining a groove which extends into the core from the top surface of the core;
• providing at least one sensing coil positioned around the groove of the core;
• supplying an electronic signal to the sensing coil;
• and
• measuring the inductance over the sensing coil, and if the inductance varies greater than a predetermined value, generating a signal to indicate the presence of the ferromagnetic object.

A method for detecting the presence of a conductive object which comprises:

• providing a core formed of a permeable material, the core having a generally planar top surface, a bottom, a side surface having a width between the top and the bottom surface of the core, and an outer perimeter bounding the side surface of the core, the core defining a groove which extends into the core from the top surface of the core;
• providing at least one sensing coil positioned around the groove of the core;
• supplying an electronic signal to the sensing coil;
• and
• measuring the inductance over the sensing coil, and if the inductance varies greater than a predetermined value, generating a signal to indicate the presence of the conductive object.