Two-Headed DC Magnetic Target Proximity Sensor.
DEPARTMENT OF THE NAVY WASHINGTON DC
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A magnetic proximity sensor for detecting the proximity of a laterally moving magnetized target moving along a translation axis which is parallel to a line joining the targets magnetic poles, including two ring-core flux-gate magnetometers disposed adjacent to each other with their axes of sensitivity in parallel, with both axes perpendicular to the magnetized target translation axis. The energizing coils of the flux-gate magnetometers are driven by an ac signal at frequency fo. The signal on the detecting coils in each flux-gate magnetometer is applied to a phase comparator via a bandpass filter tuned to the second harmonic of fo. When the signals applied to the phase comparator are of opposite phase, then the center plane equidistant from the targets magnetic poles is between the two axes of sensitivity of the magnetometers. When the signals are of the same phase, then the targets center plane is laterally outside of the these two axes.
- Magnetic and Electric Field Detection and Detectors
- Electricity and Magnetism