Cathode-ray tube and system to eliminate electrical discharges during indexing

Claim 2

In a cathode-ray tube indexing system comprising a cathoderay tube the envelope of which includes an electrically insulating portion, means for generating a cathode-ray beam in said tube, high-voltage means in said tube for accelerating said beam toward the inner surface of said envelope portion, index elements in said tube adjacent predetermined areas of said inner surface of said envelope portion and responsive to impingement by said beam to generate detectable index emanations, means responsive to deflection signals for deflecting said beam to cause it to traverse said index elements, and means responsive to said emanations to produce electrical index signals indicative of the times at which said index elements are impinged by said beam: the improvement which comprises a layer of electricallyconductive material extending over and in intimate contact with the exterior surface of said envelope portion adjacent said areas of said inner surface, and means for maintaining said layer at a substantially fixed potential.

Claim 3

Apparatus in accordance with claim 1, in which said layer comprises an adherent coating of electrically-conductive material on said exterior surface.

Claim 4

Apparatus in accordance with claim 1, in which said means for maintaining said layer at a substantially fixed potential comprises an electrical connection to said layer and a source of substantially fixed potential connected to said connection.

Claim 5

Apparatus in accordance with claim 3, in which said connection comprises a metal band extending around said tube and over and against said coating.

Claim 6

Apparatus in accordance with claim 1, in which said envelope contains image-presentation means at the front of said tube for producing an image in response to impingement by said beam when it scans across said image-presentation means from one side to the other thereof, and in which said layer extends along the exterior of said tube adjacent said one side of said image-presentation means.

Claim 7

Apparatus in accordance with claim 5, in which at least some of said index elements extend outside the normal viewing area of said image-presentation means and said layer is disposed on the outer surface of said envelope adjacent said at least some index elements.

Claim 8

Apparatus in accordance with claim 1, in which said tube contains color image-presentation means at the front thereof comprising an image-forming area made up of a plurality of different phosphor elements differently responsive to impingement by said beam to produce light of differing colors, said deflecting means being effective, when operated, to scan said image-forming aRea from one side to the other thereof with said beam, said index elements being located at predetermined positions with respect to said phosphor elements including positions adjacent said one side, said layer extending over a part of said insulating portion of said tube adjacent said one side.

Claim 9

Apparatus in accordance with claim 1, in which said tube comprises a transparent front face having on the inner surface thereof a layer of phosphor elements arranged in a regular order and differently responsive to impingement by said beam to produce light of differing colors throughout a normal viewing area, and a metallic layer pervious to said beam and disposed over said phosphor layer on the side from which said beam approaches said phosphor layer, at least some of said index elements being located adjacent but beyond one edge of said viewing area and on said metallic layer, said layer of electrically conductive material extending along the side surface of said tube adjacent said edge.

Claim 10

In a cathode-ray indexing tube comprising a set of laterally spaced-apart running index stripes in said tube positioned to be impinged sucessively with a first periodicity by the cathode-ray tube beam as it is deflected tranversely to said stripes to produce an ambiguous index signal representative of the position of said beam with respect to said running stripes, and at least one starting stripe along one edge of said set in predetermined laterally-spaced relation to said set of running index stripes for producing another index signal indicative of the position of said beam with respect to a particular one of said running stripes, the improvement comprising: a layer of electrically-conductive material in intimate contact with the exterior of said tube in a position adjacent said at least one starting stripe.

Claim 11

In a cathode-ray indexing tube comprising a set of laterally spaced-apart running index stripes in said tube positioned to be impinged sucessively with a first periodicity by the cathode-ray tube beam as it is deflected tranversely to said stripes to produce an ambiguous index signal representative of the position of said beam with respect to said running stripes, and at least one starting stripe along one edge of said set in predetermined laterally-spaced relation to said set of running index stripes for producing another index signal indicative of the position of said beam with respect to a particular one of said running stripes, the improvement comprising: a layer of electrically-conductive material in intimate contact with the exterior of said tube in a position adjacent said at least one starting stripe.

Claim 12

In the tube of claim 9, means for maintaining said layer at a substantially fixed potential.

Claim 13

In a color television image-presentation tube comprising a cathode-ray tube envelope, means for forming a cathode-ray beam in said tube, a transparent front face on said tube, color-image forming means on said front face and comprising an array of periodically-positioned groups of light-emissive stripes, different stripes in each group being differently responsive to impingement by said beam to produce light of differing colors, means for scanning said beam transversely to said stripes at successively different vertical positions to produce a television raster on said color-image forming means, means responsive to color television signals and to index signals for controlling the intensity of said beam as it scans the stripes in each of said groups to produce a color of light from each successively scanned group area which is appropriate to the desired color of the television image in that area, a conducting layer extending over said image-forming means on the side of approach by said beam, a plurality of running photo-index stripes periodically recurrent in the horizontal direction along said image-forming means on the side of said conductive layer impinged by said beam and recurrent transversely of said image-forming means with a periodicity different from that of said light-emissive stripes, starting photo-index stripes positioned on said side of said conductive layer and adjacent the edge of said image-forming means first impinged by said beam in its horizontal scannings, said starting stripes having a different periodicity along said horizontal direction than said running stripes, and means responsive to light emanations from said starting stripes and from said running stripes to generate an index signal representative of the instantaneous horizontal position of said beam, the improvement comprising: an intimate continuous electrically-conductive coating on the exterior of said tube adjacent said edge of said image-forming means.

Claim 14

In a color television image-presentation tube comprising a cathode-ray tube envelope, means for forming a cathode-ray beam in said tube, a transparent front face on said tube, color-image forming means on said front face and comprising an array of periodically-positioned groups of light-emissive stripes, different stripes in each group being differently responsive to impingement by said beam to produce light of differing colors, means for scanning said beam transversely to said stripes at successively different vertical positions to produce a television raster on said color-image forming means, means responsive to color television signals and to index signals for controlling the intensity of said beam as it scans the stripes in each of said groups to produce a color of light from each successively scanned group area which is appropriate to the desired color of the television image in that area, a conducting layer extending over said image-forming means on the side of approach by said beam, a plurality of running photo-index stripes periodically recurrent in the horizontal direction along said image-forming means on the side of said conductive layer impinged by said beam and recurrent transversely of said image-forming means with a periodicity different from that of said light-emissive stripes, starting photo-index stripes positioned on said side of said conductive layer and adjacent the edge of said image-forming means first impinged by said beam in its horizontal scannings, said starting stripes having a different periodicity along said horizontal direction than said running stripes, and means responsive to light emanations from said starting stripes and from said running stripes to generate an index signal representative of the instantaneous horizontal position of said beam, the improvement comprising: an intimate continuous electrically-conductive coating on the exterior of said tube adjacent said edge of said image-forming means.

Claim 15

In a beam-indexing color-image display cathode-ray tube having a beam-indexing structure therein responsive to impingement by the beam as it performs successive horizontal line-scanning of said structure to produce index signals, the improvement which comprises means for maintaining at a substantially fixed potential the exterior portions of said tube adjacent the regions of said structure at which said line-scannings begin.

Claim 16

In a beam-indexing color-image display cathode-ray tube having a beam-indexing structure therein responsive to impingement by the beam as it performs successive horizontal line-scanning of said structure to produce index signals, the improvement which comprises means for maintaining at a substantially fixed potential the exterior portions of said tube adjacent the regions of said structure at which said line-scannings begin.

Claim 17

The tube of claim 12, in which said structure includes a portion along one edge thereof at which said scannings being for producing unambiguous indications of impingement by said beam, and said means for maintaining said exterior portions of said tube at a substantially fixed potential comprises a conductive coating overlying said exterior portions and means for maintaining said coating at a substantially fixed potential.

Claim 18

The tube of claim 13, in which said tube is of the type employing groups of generally-vertical image-forming line segments differently responsive to impingement by said beam to produce light of different colors extending throughout a normal viewing area and said beam-indexing structure comprises an array of beam responsive index line segments disposed inwardly of said tube from said image-forming line segments and in predetermined geometric relation thereto, said array including index line segments positioned along said edge.