CRT magnetic field cancelling device
AssigneeZenith Electronics Corporation
InventorWayne D. Grocki
Life of this patent
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Abstract
A stray magnetic field cancelling device for a cathode ray tube comprises an elongated member of adjustable length composed of at least two magnetizable metal plates in slidable relationship enveloped by an electromagnetic coil. The device is physically isolated from the yoke a distance effective to exert minimum effect on the yoke deflection fields. Also, the device is oriented transversely to the centerline of the cathode ray tube so as to generate a cancelling magnetic field in opposed relationship with, and transverse to, the stray magnetic field. A simple mechanical adjustment provides for adapting the device to CRTs of varying sizes.
Claims18
A CRT stray field cancelling device for abating a stray magnetic field emanating from a vertical deflection coil of a yoke, the device comprising an elongated member of adjustable length composed of at least two magnetizable metal plates in slidable relationship enveloped by an electromagnetic coil, the device being physically isolated from the yoke a distance effective to exert minimum effect on the yoke deflection fields, and oriented transversely to the centerline of a CRT so as to generate a cancelling magnetic field in opposed relationship with, and transverse to, the stray magnetic field.
A CRT stray field cancelling device for abating a stray magnetic field emanating from the vertical deflection coil of a CRT yoke, the device comprising a lamination composed of a pair of key-shaped, magnetizable metal plates, the blades of which are in facing relationship and overlap to form the device into an irregular octagon having a central recess tapering from the bows of the key-shaped magnetizable metal plates for receiving an electromagnetic coil.
A monochrome monitor housed in a cabinet and including a cathode ray tube having a yoke with a vertical deflection coil that radiates a stray magnetic field outside the cabinet, a stray field cancelling device comprising an elongated, substantially rectangular lamination composed of a pair of magnetizable metal plates having a depressed center section enveloped by an electromagnetic coil for generating a magnetic field cancelling the stray magnetic field, the device being physically isolated from the yoke and oriented transversely to the centerline of the cathode ray tube so as to generate a cancelling magnetic field in opposed relationship to, and out of phase with, the stray magnetic field.
Dependencies are inferred from the claim text.