| 摘要 |
<p>AN APPARATUS FOR DETECTING A FERROMAGNETIC MATERIAL An apparatus for detecting a ferromagnetic material in a predetermined area. A convertor (24) is used having an impedance responsive to the magnetic field intensity of the earth. The convertor (24) may be coupled to a detector (16) for monitoring the impedance of the convertor (24) and generating a call signal responsive to the change in impedance. Generally, the impedance is primarily inductance and the detector (16) is an oscillator using the convertor (24) in a resonant circuit with a frequency monitor coupled to the detector. The convertor (24) is an open magnetic structure having a non-linear BH curve (34) biased by the earth's magnetic field. The open magnetic structure is a core (68) of a highly permeable material saturable under the influence of the earth's magnetic field, with the axis of the core at least partially aligned with the magnetic flux lines of the earth's magnetic field, and a coil (70) wound around the axis of the core.</p> |
