Cathode-ray tube having an internal-external magnetic shield and degaussing combination

Claim 2

In a shadow mask type cathode-ray tube, the improvement comprising, an internal-external magnetic shield and degaussing coil combination including, an internal shield portion interconnected to said mask, said internal shield having an opening therein remote from said mask, the opening including two opposite gaps extending towards said mask, and two external shield portions overlapping said internal shield portion and covering the gaps in said internal shield portion, each of said external shield portions extending along a side of said tube and having a degaussing coil thereon.

Claim 3

The cathode-ray tube as defined in claim 1, including a peripheral electron trap positioned at the intersection of said mask and said internal magnetic shield, said trap having an inwardly extending portion for stopping over-scanned electron beams deflected off said internal magnetic shield from striking a screen of said tube.

Claim 4

In a shadow mask type cathode-ray tube, the improvement comprising, an external magnetic shield attached to an outside surface of said cathode-ray tube including two separated portions, one portion on each side of said tube, and each of said portions extending less than halfway around said tube from an upper section to a lower section of said tube when said tube is in its operational orientation, and at least two degaussing coils, each horizontally wrapped around an external shield portion, whereby the external magnetic shield portions provide cores for the degaussing coils that direct the degaussing magnetic fields to the upper and lower portions of said tube.

Claim 5

In a shadow mask type cathode-ray tube, the improvement comprising, an external magnetic shield attached to an outside surface of said cathode-ray tube including two separated portions, one portion on each side of said tube, and each of said portions extending less than halfway around said tube from an upper section to a lower section of said tube when said tube is in its operational orientation, and at least two degaussing coils, each horizontally wrapped around an external shield portion, whereby the external magnetic shield portions provide cores for the degaussing coils that direct the degaussing magnetic fields to the upper and lower portions of said tube.

Claim 6

In a shadow mask type cathode-ray tube, the improvement comprising, means for forming a degaussing field extending vertically through a shadow mask in said tube when said tube is in an operational orientation, and an internal magnetic shield peripherally interconnected to the shadow mask of said tube, said internal magnetic shield generally conforming to the interior shape of a section of said tube and having a central opening therethrough facing away from said mask substantially wider in a horizontal direction than in the vertical direction extending in the horizontal direction to the vicinity of the mask periphery, whereby said degaussing field is directed to follow a path through the mask instead of through the internal magnetic shield.

Claim 7

In a shadow mask type cathode-ray tube, the improvement comprising, means for forming a degaussing field extending vertically through a shadow mask in said tube when said tube is in an operational orientation, and an internal magnetic shield peripherally interconnected to the shadow mask of said tube, said internal magnetic shield generally conforming to the interior shape of a section of said tube and having a central opening therethrough facing away from said mask substantially wider in a horizontal direction than in the vertical direction extending in the horizontal direction to the vicinity of the mask periphery, whereby said degaussing field is directed to follow a path through the mask instead of through the internal magnetic shield.

Claim 8

The cathode-ray tube as defined in claim 4, wherein said internal magnetic shield comprises two interconnected portions, each portion having a peripheral edge shape of half of said mask and another peripheral cresent shaped edge, the cresent shaped edges of both sections comprising the periphery of the central opening in said internal magnetic shield.

Claim 9

The cathode-ray tube as defined in claim 4, including a peripheral electron trap positioned at a larger end of said internal magnetic shield, said trap having an inwardly extending portion for stopping over-scanned electron beams deflected off said internal magnetic shield from striking a screen of said tube.

Claim 10

The cathode-ray tube as defined in claim 6, wherein said inwardly extending portion of said trap at any particular peripheral location forms an angle of less than half the maximum electron beam deflection angle relative to a plane perpendicular to the central axis of said tube at the peripheral location.