Importance

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Abstract

Apparatus and methods for resolving movement of a mass within a defined space utilizes at least one electrode proximate to the space to be observed. An AC signal is applied to the electrode, and the current measured from that electrode and also to any other electrodes included in the system and which are effectively connected to the ground return of the AC-coupled electrode. A person (or object) to be sensed intercepts a part of the electric field extending beween the AC-coupled 'sending' electrode and the other 'receiving' electrodes, the amount of the field intercepted depending on the size and orientation of the sensed person, whether or not the person provides a grounding path, and the geometry of the distributed electrodes. Given the nonlinear spatial dependence of the field, multiple electrodes can reliably distinguish among a set of expected cases. The invention detects motion by taking sequential measurements at different times and utilizing the time variation in signal magnitudes as well as the absolute magnitudes themselves.

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First Claim