Blackening of non-iron-based flat tensioned foil shadow masks
AssigneeZenith Electronics Corporation
InventorHua Sou Tong
Life of this patent
Estimating the term…
Abstract
The power handling capacity of non iron-based flat tensioned foil shadow masks for flat faceplate cathode ray tubes (CRTs) is enhanced by providing the flat tensioned mask (FTM) with a thin outer layer of iron, which is converted to iron oxide by blackening, or heating. The iron layer, which is preferably at least 0.04 mil thick, is deposited on the FTM by electroplating in a ferrous ammonium sulfate bath either before or after chemical etching of the FTM. The thin iron layer increases FTM emissivity and reduces FTM doming at high electron beam energies. The iron coating may be blackened in the frit-like cycle during CRT assembly or in a separate heating operation. A blackened outer layer of cobalt may also be used to increase FTM emissivity.
Claims29
A process for manufacturing a tensioned mask color cathode ray tube which includes a faceplate having on its inner surface a phosphor screen and a support structure for said mask, the process comprising:
- providing a non iron-based apertured foil shadow mask, said shadow mask comprising between about 75 to 85 weight-percent nickel, between about 3 and 5 weight-percent molybdenum, with the balance iron and incidental impurities;
- depositing a thin layer of iron on the surface of said shadow marks;
- converting said thin layer of iron to iron oxide;
- and
- securing said shadow mask to said support structure while under tension in registration with said phosphor screen.
A process for manufacturing a tensioned mask color cathode ray tube which includes a faceplate having on its inner surface a phosphor screen and a support structure for said mask, the process comprising:
- providing an apertured foil shadow mask characterized by being composed of an alloy containing between about 30 and about 85 weight-percent nickel, between about 0 and 5 weight-percent molybdenum, between 0 and 2 weight-percent of one or more of vanadium, titanium, hafnium, and niobium, with the balance iron and incidental impurities;
- depositing a thin layer of iron on said foil mask at least 0.04 mil thick;
- converting said thin layer of iron to iron oxide;
- and
- securing said foil mask to said support structure while under tension and in registration with said phosphor screen.
The process according to claim 5 wherein converting said thin layer of iron to iron oxide is accomplished as a discrete step prior to installing said mask on said support structure.
In the manufacture of a color cathode ray tube including a faceplate having on its inner surface a centrally disposed phosphor screening area embraced by a peripheral sealing area adapted to mate with a funnel, the process comprising:
- securing a frame-like shadow mask-support structure on said faceplate inner surface between said peripheral sealing area and said screening area for receiving and supporting a foil shadow mask in tension;
- providing a non iron-based allow;
- forming said alloy into a thin foil;
- aperturing a central area of said foil to form a foil mask consonant in dimensions with said screening area for color selecting, said non-iron based alloy comprising between about 75 and 85 weight-percent nickel, between about 3 and 5 weight-percent molybdenum, with the balance iron and incidental impurities;
- depositing a thin layer of iron on said foil mask;
- converting said thin layer of iron to iron oxide;
- sequentially photoscreening a pattern of red-light-emitting, green-light-emitting, and blue-light-emitting phosphor deposits on said screening area;
- securing said foil mask to said mask-support structure with said apertures in registration with said pattern;
- applying a devitrifiable frit in paste form to said peripheral sealing area for receiving a funnel;
- mating said faceplate with said funnel to form a faceplate-funnel assembly;
- and
- heating said assembly to devitrify said frit and permanently attach said funnel to said faceplate.
A process for making a foil shadow mask for use in a tensioned mask color cathode ray tube having a desirable emissivity, said process comprising:
- providing a foil mask composed of an alloy containing between about 75 and about 85 weight-percent nickel, between about 0 and 5 weight-percent molybdenum, between 0 and 2 weight-percent of one or more of vanadium, titanium, hafnium, and niobium, with the balance iron and incidental impurities;
- depositing a thin layer of iron on said foil mask;
- and
- blackened the thin layer of iron by heating said foil mask to an elevated temperature.
A process for manufacturing a tensioned mask color cathode ray tube which includes a faceplate having on its inner surface a phosphor screen and a support structure for said mask, the process comprising:
- providing a non iron-based apertured foil shadow mask, said shadow mask comprising between about 75 and 85 weight-percent nickel, between about 3 and 5 weight-percent molybdenum, with the balance iron and incidental impurities;
- depositing a thin layer of cobalt on the surface of said shadow mask;
- converting said thin layer of cobalt to cobalt oxide;
- and
- securing said shadow mask to said support structure while under tension in registration with said phosphor screen.
A process for manufacturing a tensioned mask color cathode ray tube which includes a faceplate having on its inner surface a phosphor screen and a support structure for said mask, the process comprising:
- providing an apertured foil shadow mask characterized by being composed of an alloy containing between about 75 and about 85 weight-percent nickel, between about 0 and 5 weight-percent molybdenum, between 0 and 2 weight-percent of one or more of vanadium, titanium, hafnium, and niobium, with the balance iron and incidental impurities;
- depositing a thin layer of cobalt on said foil mask at least 0.04 mil thick;
- converting said thin layer of cobalt to cobalt oxide;
- and
- securing said foil mask to said support structure while under tension and in registration with said phosphor screen.
Dependencies are inferred from the claim text.