US 4,826,463 A · Sealing for CRT components

Abstract

Improved bonding in a cathode ray tube (CRT) between its glass funnel and glass faceplate is achieved by applying a thin base layer of a priming agent to an aft portion of the faceplate adjacent to the periphery thereof as well as to the forward edge of the funnel prior to positioning of the CRT components in contact. An intermediate layer of sealing glass frit is then deposited upon either of the aforementioned layers of the priming agent and adheres to the two priming agent layers without forming a re-entrant geometry. By "priming" the two abutting glass surfaces over an area which extends beyond the area of high loading with the priming agent prior to joining these surfaces, bond integrity is ensured and high stress concentration in the seal is avoided. The sealing glass frit may be comprised of a conventional glass cement paste and is also used as the priming agent in a preferred embodiment. The improved bonding method may also be used to bond a shadow mask support structure to the faceplate's inner surface or other CRT components to each other. Improved CRT components and assemblies made by the disclosed method are also disclosed.

Claims19

Dependent claims

In the manufacture of color cathode ray tubes, a method of joining two components composed of glass, ceramic, metal or other material amenable to being bonded together by the use of frit-based or other vitreous cement characterized by having a high cohesiveness and low propensity for wetting said components to be joined such that re-entrancies may be formed in the joint which tend to weaken the joint when subjected to loading, said method comprising:

providing a first component having a predetermined first sealing area and a second component having a predetermined second sealing area adapted to mate with said first sealing area;
applying to at least one of said sealing areas a viscous layer of cement comprised of a frit-based or other vitreous material characterized by having properties of high cohesion and low propensity for wetting said components;
and
mating said components along said sealing areas and baking the assembled combination to harden said cement,
said method being characterized by including the step prior to said applying of said cement of applying a viscous priming layer of said same vitreous cement on at least one of said sealing areas which is composed of a material to which said cement has a high wetting affinity, the terminations of said viscous priming layer being caused to lie in regions of low stress outside the joint, whereby the resultant joint has a substantially reduced or non-existent tendency to form re-entrant seals in the component interface area where stresses when the joint is loaded may be high, thereby markedly reducing joint failures due to stress concentrations in the joint region, and whereby any stress concentrations resulting from re-entrancies formed at said terminations of said viscous priming layer, being in regions of low stress, are relatively harmless.

2 more elements

A method of producing an improved frit-seal between the funnel and the flat faceplate of a tension-mask-type color cathode ray tube which seals tend to be more susceptible to failure than cathode ray tubes having a curvilinear faceplate due to the unusually high stresses created at the funnel-faceplate joint of such flat-faceplate tubes, said method comprising:

providing a glass funnel having a predetermined sealing area and a flat glass faceplate having a predetermined sealing area adapted to mate with said funnel sealing area;
applying to said sealing areas a viscous bead of cement comprised of a frit-based material characterized by having properties of high cohesion and poor wetting of glass;
and
mating said faceplate and funnel sealing areas and baking the assembled combination to harden said cement,
said method being characterized by including the step prior to said applying said cement of applying a priming layer on at least one of said sealing areas composed of a material to which said frit cement has a high wetting affinity, the terminations of said priming layer being caused to lie in regions of low stress outside the faceplat-funnel interface, whereby the resultant faceplate-funnel joint has a substantially reduced or non-existent tendency to form re-entrant seals in the faceplate-funnel interface where stresses are high, thereby markedly reducing joint failures due to stress concentratoions in the joint region, and whereby any stress concentrations resulting from re-entrancies formed at said terminations of said layer, being in regions of low stress, are relatively harmless.

2 more elements

A method of frit-sealing the funnel and the faceplate of a cathode ray tube, comprising:

providing a glass funnel having a first sealing area and a glass faceplate having a second sealing area adapted to mate with said funnel sealing area;
applying a first layer of frit-based sealing glass to said first sealing area and a second layer of said frit-based sealing glass to said second sealing area in a manner such that said frit-based sealing glass layers extend beyond said sealing areas, wherein said frit-based sealing glass is characterized as having properties of high cohesion and poor wetting of glass;
applying an intermediate layer of said frit-based sealing glass to said first or said second layer of said frit-based sealing glass;
and
mating said respective first and second sealing areas of said funnel and said faceplate and baking the assembled combination to harden said frit-based sealing glass, wherein the terminations of said intermediate layer of said frit-based sealing glass lie in regions of low stress outside the faceplate-funnel interface, whereby the resultant faceplate-funnel joint has a substantially reduced or non-existent tendency to form re-entrant seals in the faceplate-funnel interface where stresses are high, thereby markedly reducing joint failures due to stress concentrations in the joint region, and whereby any stress concentrations resulting from re-entrancies formed at said terminations of said layer, being in regions of low stress, are relatively harmless.

2 more elements

A method of frit-sealing the shadow mask support structure and the faceplate of a cathode ray tube, comprising:

providing a ceramic shadow mask support structure having a first sealing area and a glass faceplate having a second sealing area adapted to mate with said support structure sealing area;
applying a first priming layer of frit-based sealing glass to said first sealing area and a second priming layer of said frit-based sealing glass to said second sealing area in a manner such that said frit-based sealing glass priming layers extend beyond said sealing areas, wherein said frit-based sealing glass is characterized as having properties of high cohesion and poor wetting of glass and ceramic;
applying an intermediate layer of said frit-based sealing glass to said first or said second layer of said frit-based sealing glass;
and
mating said respective first and second sealing areas of said support structure and said faceplate and baking the assembled combination to harden said frit-based sealing glass, wherein the terminations of said priming layers lie in regions of low stress outside the shadow mask support structure-faceplate interface, whereby the resultant shadow mask support structure-faceplate joint has a substantially reduced or non-existent tendency to form re-entrant seals in the shadow mask support structure-faceplate interface where stresses are high, thereby markedly reducing joint failures due to stress concentrations in the joint region, and whereby any stress concentrations resulting from re-entrancies formed at said terminations and said priming layers, being in regions of low stress, are relatively harmless.

2 more elements

Dependencies are inferred from the claim text.

Sealing for CRT components

Life of this patent

Sealing for CRT components

Life of this patent

Abstract

Claims19