Importance

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Abstract

A magnetic field position and orientation measurement system contains, confines and re-directs the magnetic field from one or more transmitters such that the fields are attenuated in areas outside of the operating volume in areas where metallic objects are commonly found. A thin barrier made of a highly permeable material such as ferrite or mumetal is placed on top of a conductive plate. The thickness of the permeable layer is from 0.01 inches to 0.25 inches while the conductive plate, preferably made of an aluminum alloy, may preferably be from 3/16 of an inch to 1/4 inch in thickness. On top of the permeable barrier, a rhombic three axis transmitter is placed. In the preferred embodiment, the transmitter consists of a PC board carrying the transmitter. PC boards having thicknesses varying from 0.03125-0.125 inches may be employed. Thus, the entire 'stack' including the transmitter, the permeable barrier and the conductive plate may only be from 1/2 inch to 5/8 of an inch in thickness. The permeable barrier may have a flat, planar configuration. Alternatively, it may be made to resemble, in cross-section, a cake pan having a flat central region with uplifted peripheral edges. Alternatively, the permeable barrier may have a generally flat configuration with peripheral edges that taper outwardly from the top surface thereof to the bottom surface thereof with the taper making an angle with the bottom surface in the range of, preferably, 30.degree. to 85.degree..

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First Claim