Importance

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Abstract

A device (16) for sensing current flowing in a generally flat plate structure (10) contains a magnetic head (18) and signal processing circuitry (20). The magnetic head (a) senses changes in current-induced magnetic flux as the head is positioned over the plate structure and (b) provides a head output signal. The signal processing circuitry processes the head output signal to produce a data signal indicative of how much current appears to flow in the plate structure below the head. A driving voltage, which typically varies in a periodic manner to produce a characteristic signature, is applied to a primary conductor in the plate structure. A location sensor, typically formed with a light source (100) and a light sensor (102), detects the position of the magnetic head relative to the plate structure. A gas-cushion mechanism (80-98) controls the height of the head above the plate structure.

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First Claim