Method for grading the screen of a color tube

Claim 1

IN THE FORMATION OF A SCREEN FOR A COLOR CATHODE RAY TUBE, A METHOD FOR EXPOSING A PHOTOSENSITIVE COATING ON A CATHODE RAY TUBE FACEPLATE COMPRISING ILLUMINATING THE COATING WITH RADIATION ACTINIC TO SAID COATING EMANATING FROM AN EFFECTIVE POINT SOURCE THROUGH A SHADOW MASK DISPOSED ADJACENT TO SAID COATING HAVING A PREDETERMINED PATTERN OF APERTURES FORMED THEREIN SO AS TO IMPRESS ON THE COATING A CORRESPONDING PATTERN OF LATENT APERTURE IMAGES, SAID METHOD INCLUDING ALTERING THE ENERGY DISTRIBUTION PATTERN IMPRESED ON THE COATING THROUGH THE MASK BY SHADING SAID COATING AS A FUNCTION OF (I) TIME, (II) THE RADIAL DISTANCE OF LATENT IMAGES FROM FACEPLATE CENTER, AND (II) THE AZIMUTHAL ANGLE OF LATENT IMAGES ON THE FACEPLATE, SUCH THAT THREE IS DEFINED ON THE FACEPLATE COATING A PLURALITY OF NON-CIRCULAR LOCI WHEREIN EACH SAID NON-CIRCULAR LOCUS CONSISTS OF LATENT IMAGES WHICH RECEIVE AN EQUAL TIME OF EXPOSURE, WHEREIN SAID SHADING COMPRISES CASTING TWO SHADOW PATTERNS ON SAID MASK WHICH MOVE WITH TIME ACROSS SAID MASK IN SUBSTANTIALLY ORTHOGONAL DIRECTIONS, EACH OF SAID SHADOW PATTERNS COMPRISING FIRST AND SECOND PORTIONS MOVING WITH TIME ALONG THE SAME AXIS IN OPPOSITE DIRECTIONS.

Claim 9

The method of manufacturing a rectangular screen assembly for a black surround color tube comprising the steps of: a. applying a coating of photosensitive material to the faceplate of the tube; b. mounting a shadow mask with a pattern of apertures in spaced relationship to the faceplate; c. providing a lighthouse having an exposure surface, a source of energy actinic to said photosensitive coating and an automatic shading mechanism between the energy source and the exposure surface, said shading mechanism casting two shadow patterns on said mask which move with time across said mask in substantially orthogonal directions, each of said shadow patterns comprising first and second portions moving with time along the same axis in opposite directions; d. mounting the faceplate and shadow mask on the exposure surface; e. exposing the photosensitive coating from the source of energy through the shadow mask, while varying the time of exposure with said automatic shading mechanism such that time of exposure of coating elements associated with said mask apertures depends upon the radial distance of coating elements from faceplate center and upon azimuthal angle of coating elements on the faceplate, such that there is defined on the faceplate coating a plurality of substantially rectangular, faceplate centered, and concentric loci wherein each said locus consists of coating elements which receive an equal time of exposure; f. developing the latent image of said pattern of apertures formed in said coating; and g. applying a black pigment to the non-exposed portions of said faceplate.

Claim 10

The method of manufacturing a rectangular screen assembly for a black surround color tube comprising the steps of: a. applying a coating of photosensitive material to the faceplate of the tube; b. mounting a shadow mask with a pattern of apertures in spaced relationship to the faceplate; c. providing a lighthouse having an exposure surface, a source of energy actinic to said photosensitive coating and an automatic shading mechanism between the energy source and the exposure surface, said shading mechanism casting two shadow patterns on said mask which move with time across said mask in substantially orthogonal directions, each of said shadow patterns comprising first and second portions moving with time along the same axis in opposite directions; d. mounting the faceplate and shadow mask on the exposure surface; e. exposing the photosensitive coating from the source of energy through the shadow mask, while varying the time of exposure with said automatic shading mechanism such that time of exposure of coating elements associated with said mask apertures depends upon the radial distance of coating elements from faceplate center and upon azimuthal angle of coating elements on the faceplate, such that there is defined on the faceplate coating a plurality of substantially rectangular, faceplate centered, and concentric loci wherein each said locus consists of coating elements which receive an equal time of exposure; f. developing the latent image of said pattern of apertures formed in said coating; and g. applying a black pigment to the non-exposed portions of said faceplate.