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US 5,066,891 AGranted
Magnetic field cancellation circuit
AssigneeRaytheon Company
InventorsWilliam J. Harrold, Joseph A. Sansone, Joseph W. Bonfiglio, Seung K. Kim
Life of this patent
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AssigneeRaytheon Company
InventorsWilliam J. Harrold, Joseph A. Sansone, Joseph W. Bonfiglio, Seung K. Kim
Estimating the term…
A magnetic field sensing and canceling circuit for use with a cathode ray tube (CRT) has a closed loop system consisting of flux gate sensors to measure external magnetic fields and magnetic field cancellation coils around the perimeter of the faceplate of the CRT to cancel the fields and thus minimize color and positional ac image distortion. The coils are mounted on an enclosure fabricated of a high permeability material and are positioned around the perimeter of the CRT's faceplate. Four of the coils are parallel to the top, bottom, and sides of the enclosure opening and a fifth coil is wound around the enclosure adjacent the CRT faceplate. The magnetic flux gate sensors provide output signals that are functions of the detected fields. These signals control the current in the magetic field cancellation coils and thus control the cancellation fields.
Apparatus for controlling the total magnetic field in the vicinity of a substantially plane opening of a partially open magnetic shield to a predetermined level, said magnetic shield including a flange portion defining said substantially plane opening, said apparatus comprising:
In combination:
Dependencies are inferred from the claim text.