US 4,305,055 AGranted

Television display system incorporating a coma corrected deflection yoke

AssigneeRCA Corporation

InventorThomas A. Marett, Jr.

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Abstract

A television display system comprises a kinescope, deflection yoke and magnetic field influencing apparatus. The field influencing apparatus comprises a pair of magnetically permeable members disposed on either side of the yoke. One end of each member is positioned within the external field of the toroidally-wound vertical deflection coil. The other end of each member is divided into an upper and lower field-forming arm. The upper arms of each member are disposed adjacent each other such that a gap is formed between them in the vicinity of the entrance end of the yoke. The lower arms are similarly disposed. The gaps are vertically aligned with the longitudinal axis of the kinescope. The width of the gaps is less than the spacing between the outer electron beams in the vicinity of the entrance end of the yoke. Flux from the external field is channeled into each permeable member to the ends of the field-forming arms. A field is produced between the upper arms of each member and the lower arms of each member. This field has a pincushion-shaped configuration within the tube neck for correcting vertical coma errors without undesirably interacting with the outer electron beams.

Claims5

Dependent claims

In a television display system having a kinescope incorporating an electron beam assembly disposed within the neck of said kinescope for producing a set of three in-line electron beams, the centrally located one of said beams being produced in substantial alignment with the longitudinal axis of said kinescope, and a deflection yoke encircling the paths of said beams departing said electron gun assembly and comprising a deflection coil for producing an internal vertical deflection field and an external field, said deflection yoke deflecting said beams to form three substantially superimposed rasters;

a magnetic field influencing apparatus comprising:
first and second magnetically permeable members, disposed on opposite sides of said yoke, each of said first and second members having a first end disposed within said external field and a second end disposed adjacent said kinescope neck in the vicinity of the entrance end of said yoke, each of said second ends of said first and second members being bifurcated to form upper and lower field-forming arms, the termination of said upper arm of said first member and the termination of said upper arm of said second member forming a first gap therebetween, the termination of said lower arm of said first member and the termination of said lower arm of said second member forming a second gap therebetween, each of said first and second gaps being vertically aligned with said longitudinal axis of said kinescope, the width of each of said first and second gaps being less than the distance between the outer beams of said electron beam set in the vicinity of the entrance end of said deflection yoke.

Dependencies are inferred from the claim text.