Suppression of External Magnetic Induction Caused by CRT Deflection Windings
Original Publication Date: 1988-Jun-01
Included in the Prior Art Database: 2005-Feb-15
This article describes a method of suppressing magnetic induction fields that emanate from the front of cathode ray tubes (CRTs) such as used in visual display units (VDUs). The magnetic induction field (B) in the immediate vicinity of a VDU is due largely to the part of the horizontal deflection winding that extends beyond the ferrite sleeve which forms part of a CRT yoke. Suppression is effected by providing a single bucking coil to cancel out the external value of B, in all directions, with a minimum of disturbance to the value of B within the CRT envelope. (Image Omitted) Suppression of rapid changes of B in the space surrounding the CRT is needed to satisfy legislation regarding possible health hazards to operators.