US2968741A

US2968741A - Cathode-ray tube manufacture

Info

Publication number: US2968741A
Application number: US383803A
Authority: US
Inventors: John F Frazier
Original assignee: Corning Glass Works
Current assignee: Corning Glass Works
Priority date: 1953-10-02
Filing date: 1953-10-02
Publication date: 1961-01-17
Anticipated expiration: 1978-01-17

Description

Jan. 17, 1961 J. F. FRAZIER CATHODE-RAY TUBE MANUFACTURE 2 Sheets-Sheet 1 Filed Oct. 2. 1953 INVENTOR. 70/77)! A flea 2/5? ATTORNEY.

Jan. 17, 1961 FRAZIER 2,968,741

CATHODE-RAY TUBE MANUFACTURE Filed 001;. 2, 1953 2 Sheets-Sheet 2 INVENTOR. Joly/Y f/EHZ/EE ATTORNE Y.

CATHODE-RAY TUBE MANUFACTURE John F. Frazier, Painted Post, N.Y., assignor to Corning Glass Works, Corning, N.Y., a corporation of New York Filed Oct. 2, 1953, Ser. No. 383,803

14 Claims. (Cl. 313-64) The present invention relates to television picture tubes and is particularly directed to the construction of such a tube of the all-glass type suitable for the reproduction of pictures in color.

Television picture reception in color can be obtained through the use of a tube that contains a suitable viewingscreen assembly which may comprise a tri-color phosphor plate and an aperture mask or other grid-like controlling element and which is suitably mounted or otherwise positioned in the panel end of the tube. Since such a viewingsoreen assembly is the same or substantially the same as the panel in area, it must be installed before the panel and the funnel are joined together. Because such viewingscreen assembly is relatively sensitive to heat, however, it is necessary that the panel and the funnel be sealed to one another in such a way as to avoid heat damage thereto. This requirement thus renders the conventional manner of sealing the glass panel to the glass funnel of an all-glass black-and-white picture tube unsuitable for the production of such a color picture tube, since the heat required to effect the seal is sufficient seriously to damage or otherwise to impair the viewing-screen assembly.

As described and claimed in a commonly owned ap plication of Wendell S. Blanding and William W. Shaver, Serial No. 383,804, filed of even date herewith, an allglass type of picture tube can be readily adapted for satisfactory use with such a viewing-screen assembly by sealing the glass panel and the glass funnel to one another through the medium of endless substantially fiat metal strip or ring elements whose outer dimensions or diameter is greater than that of the panel and the funnel. Each such endless metal strip or ring element basically comprises a relatively thick portion and an associated relatively thin portion extending outwardly therefrom with the relatively thick portion substantially conforming in configuration to and following the outline of the sealing surface of the glass panel or the glass funnel and having a width substantially only suflicient to afford a satisfactory surface for butt-sealing to the panel or the funnel. The relatively thick portion of one of such elements is butt-sealed to the sealing surface of the glass panel, and the relatively thick portion of the other element is buttsealed to the sealing surface of the glass funnel. The relatively thin portions of the two elements are in turn joined to each other in sealing relation as by welding preferably at or adjacent to their outer peripheries.

Such endless metal ring element may take various embodiments. For example, it may basically comprise a metal strip having a flat or planar relatively thick portion and an integral flat or planar relatively thin portion extending outwardly therefrom. Alternatively it may comprise a flat or planar relatively thick metal strip and an associated fiat or planar relatively thin metal strip, the latter being joined to the former in sealing relation and extending outwardly therefrom.

As more fully detailed in such Blanding-Shaver application, the mass of such a thin-thick metal sealing eleatent O ment is so distributed that no undue hoop stress and/or bending stress is created in the glass portion of the glassto-metal seal. In addition the thick portion of the element provides the rigidity desirable in the glass-to-metal seal area to prevent deformation and pulling away of the metal from the glass. Moreover, because of the thin character of the outwardly extending portions of the elements, the amount of heat required to weld them together is not sufficient to damage the glass-to-metal seals. Such relatively thin portions also possess sufficient resilience so that they can be flexed to the extent necessary in preparation for their welding together.

As further described and claimed in a commonly owned application of Francis W. Martin, Serial No. 383,871, filed on even date herewith, now Patent No. 2,925,189, such all-glass type of color picture tube envelope may desirably employ a thick-thin metal sealing element in which the relatively thick portion is non-planar, or specifically concave-convex in cross-section, for scaling to either or both the glass panel and the glass funnel.

The viewing-screen assembly embodied in such a color picture tube possesses considerable weight, the assembly for a 15-inch round tube, for example, weighing approximately six pounds and that for a 19-inch tube weighing approximately 13 pounds. In a metal-funnel picture tube, as will be appreciated, such screen assembly can be readily supported directly by the funnel without undue difiiculty. With the employment of an all-glass type of picture tube, however, an entirely different problem of screen assembly support is obviously presented.

The instant invention is particularly concerned with the adaptation of sealing elements of the general character of those disclosed and claimed in the above-referred to co-pending applications for the support of the viewingscreen assembly within an all-glass type of picture tube envelope embodying such elements. As will be apparent, such an arrangement must first of all possess sufiicient strength sturdily to support the screen assembly during use. Owing to the considerable weight of such a screen assembly, moreover, it becomes evident that its support by such a sealing element must be in such a fashion as to cushion the shock transmitted to the seal by the inertia of such assembly during any rough handling to which the picture tube may be subjected, as in shipping or in installation. As will be appreciated, such support must also be of such a nature that it enables the screen assembly to be mounted in precise alignment with the electron guns and to be maintained in such alignment despite any handling to which the tube may be subjected.

In the accompanying drawings Fig. 1 is a side elevation of an envelope embodying the invention and having a viewingscreen assembly arranged therein.

Fig. 2 is an enlarged sectional view of a fragment of the picture tube envelope of Fig. 1 showing one specific form of seal and one specific form of screen assembly support that may be embodied therein.

Fig. 2a is a fragmentary view taken generally on line 2a-2a of Fig. 2.

Figs. 3 and 4 are enlarged sectional views similar to Fig. 2 of alternative specific forms of seals and screen assembly supports that may be embodied in the envelope of Fig. 1.

Fig. 3a is a fragmentary view taken generally on line 3a-3a of Fig. 3.

Fig 5 is a fragmentary view taken generally on line 5-5 of Fig. 4.

Figs. 6 and 7 are enlarged sectional views of funnel fragments showing additional specific forms of screen assembly supports.

The envelope generally shown in Fig. l embodies panel and

funnel portions

11 and 15, a metal seal assem all-glass type of round television picture tube bly 19 which may be any of the forms illustrated in Figs. 2, 3 and 4, and a viewing-screen assembly arranged therein.

In the embodiment illustrated in Figs. 2 and 2a the panel portion 21 of a tube envelope is butt-sealed to one broad surface of the thick cross-sectional portion 22 of a metal strip or ring having an integrally adjoining thin cross-sectional portion 23 preferably, but not necessarily, with a rib 24 formed therein paralleling the seal. A similar but oppositely disposed strip or

ring comprising parts

22', 23 and 24 is in a similar fashion buttsealed to the funnel portion 25 of the tube envelope. To reduce point loading between strip portions 22 and 22' when the completed envelope is evacuated for use, a gasket 28 of soft metal or other suitable material may be provided therebetween'.

Strip portions

23 and 23 are hermetically bonded at or adjacent to their outer boundaries as at 29 preferably by welding.

Welded or otherwise fixed atspaced points along the inner margin of strip portion 22 are viewing-screen assembly support lugs or tabs such as 26 each having a post or stud such as 27, upstanding therefrom for mounting the screen assembly 20. Such tabs 26 may be substantially as thick as thick strip portion 22. or may be relatively thinner than the latter as indicated in Fig. 2. As will be appreciated, the particular thickness chosen is governed in part by the weight of the screen assembly to be supported. Desirably, this thickness should also be such that, if the tube is subjected to rough handling, the tabs will continue to properly support the screen assembly without themselves breaking or without damage to the seal between strip portion 22 and funnel 25.

Because of the physical limitations inherent in the several parts, it may be somewhat diflicult or impossible in some cases to select a thickness for the tabs suitable to provide such desired support regardless of any rough handling which the tube may undergo. Such support can be readily provided, however, by the forms of screen assembly support shown in Figs. 3, 4, 6 and 7, of which that shown in Fig. 4 I find generally preferable and most advantageous.

In the embodiment illustrated in Figs. 3 and 3a the metal sealing element includes a relatively thick strip 32 which is only of sufficient width to provide the surface necessary for the butt-seal to the panel 31. A companion strip 33 of relatively thin metal is arranged adjacent to the opposite surface of strip 32 and is joined thereto as by appropriate welding along or adjacent to the junction of their inner margins, as at 34. Oppositely disposed

corresponding strips

32 and 33 are similarly associated with respect to the funnel portion 35. Strip 33 is joined to the strip 32', preferably by suitably welding them to one another desirably along a line outward from their inner margins as at 38. It will be appreciated, of course, that the latter manner ofjoining the thick andthe thin strips may also be utilized in the panel-sealing element.

Strip 33 projects inwardly to form an annular screen assembly support 36 which has an annular stiffening rib therein paralleling its inner margin. To provide additional stiffening, support 36 is overlaid with a continuous ring 39 welded thereto and provided with spaced suitable screen assembly mounting studs such as 37. As indicated, annular support 36 is advantageously of the same thickness as thin strip 33. Support 36 and strip 33 may be fabricated as an integral unit or may be made by appropriately welding each to the other.

The preferred form of embodiment of the invention illustrated in Fig. 4 differs primarily from that shown in Fig. 3 in that the thick metal strip such as 42 is made concavo-convex in transverse cross-section and its com panion thin strip such as 43 is made to conform to the adjoining surface of strip 42 as taught and claimed in the referred-to Martin application and in that the oppositely disposed thin strip 43 extends inwardly to form the annular support 46 for the viewing screen assembly, the inner edge of which support is turned down to form integral therewith a shallow tube 46 for added rigidity. In place of a continuous ring, support 46 is advantageously provided with spaced sections or pads 49 to which screen assembly mounting studs such as 47 are welded. Pads 49 need only be sufficiently thick to enable studs 47 to be satisfactorily welded thereto.

By reason of its thinness, the

support

36 or 46 pos sesses sufficient resilience so that it can absorb the shock created by the inertia of the viewing-screen assembly due to handling of the tube without transmission thereof to the glass-to-metal seal. In addition, the continuous ring 39 or the shallow tube 46' provides the requisite strength for adequately supporting the screen assembly and for maintaining the same in proper alignment with the electron guns. Ring 39 may obviously be varied in thickness to provide the desired support strength.-

In the embodiment shown in Fig. 6, the thin strip 63 differs from strip 33 (Fig. 3) essentially in thatits inner margin is folded back upon itself to form a reinforced support 66 equivalent to support 36 (Fig. 3) and its associated' continuous ring 39. The thin strip 73 in the embodiment of Fig. 7 combines features of the structures of Figs. 4 and 6, strip 73 being bent back upon itself to provide a shallow tubular portion 79 for added strength and further to provide an underlay '78 to impart added thickness to the stud-bearing portion 76.

Any of the forms of screen assembly supports shown in Figs. 2, 3, 4, 6 and 7 may obviously be used interchangeable with any of the metal sealing elements shown in Figs. 2, 3, or 4. As will be appreciated, the screen assembly supports may alternatively be provided on the panel metal sealing strips. Also, the support tabs 26 shown in Fig. 2 may be enlarged into suitable brackets or shelves for better distribution of any shock load created by the inertia of the screen assembly in the handling of the tube.

Moreover, as explained in the referred-to Blanding- Shaver application,

strip portions

22 and 22 and 23 and 23' embodied in the metal seal assembly of Fig. 2 may respectively vary considerably in thickness. This is similarly true with respect to the strips embodied in the structures of Figs. 3, 4, 6, and 7 respectively, the optimum or desirable thickness in any instance depending to some extent on the tube size and shape and on the particular glass and metal utifized. The use of relatively thick portions or relatively thick strips ranging from 0.060 to 0.100" in thickness and of relatively thin strip portions or strips ranging from 0.020 to 0.030 in thickness has been found entirely satisfactory in the production of all-glass" 15-inch round color picture tubes.

It will also be appreciated that, while in the strip assemblie's shown, the glass surfaces have been sealed to the thick strips thereof, it is within the concept of the invention to attach the thick strip to the opposite side of the thin strip thus employing the thick strip' merely as a stiffening member and to then butt-seal the glass to the thin strip side of the assembly. Furthermore it will be apparent that, as so-called thin strips of greater thickness are employed, a corresponding reduction in thickness of the so-called thick strips can be tolerated. In other words, as the thickness of the so-called thin strip is increased, the thickness of the so-called thick strip can be correspondingly reduced, since when both such strips are sealed to one another the effectiveness of a thick strip is acquired.

As will be understood, the present invention is equally applicable for the support of viewing-screen assemblies in non-circular including the so-called rectangular type of picture tubes embodying the sealing elements of the referred-to Blanding-Shaver and Martin applications.

I claim:

1. An article comprising two glass parts, at least one of which is hollow, such parts having endless sealing surfaces facing one another, and an assembly interposed between such sealing surfaces and comprising a pair of endless metal strip elements, each such element comprising a relatively thick portion and an associated relatively thin portion extending outwardly therefrom, the relatively thick portion of one of said elements being butt-sealed to the sealing surface of one of said glass parts and the relatively thick portion of the other of said elements being buttsealed to the sealing surface of the other glass part, one of the portions of one of the elements having an inwardly extending projection for the support of a member thereon within the article, the relatively thin portions of the two elements being joined to one another in sealing relation.

2. An article comprising two glass parts, at least one of which is hollow, such parts having sealing surfaces facing one another, and as assembly interposed between such sealing surfaces and comprising a pair of endless metal elements, each such element comprising a relatively thick strip and an associated relatively thin strip, the relatively thin strip being joined to the relatively thick strip in sealing relation and extending outwardly therefrom, the relatively thick strip of one of said elements being buttsealed to the sealing surface of the glass parts and the relatively thick strip of the other of said elements being buttsealed to the sealing surface of the other glass part, the relatively thin strip of one of the elements having an inwardly extending projection for the support of a member thereon within the article, the relatively thin strips of the two elements being joined to one another in sealing relation.

3. An article such as defined by claim 2 wherein the member support comprises an inward peripheral continuation of the relatively thin strip.

4. An article such as defined by claim 3 wherein the inner marginal portion of such continuation is shaped to tubular form.

5. An article such as defined by claim 3 wherein the continuation is provided wi h an additional layer of material for added strength.

6. An article such as defined by claim 5 wherein such additional layer of material comprises a portion of such continuation bent back upon itself.

7. An article such as defined by claim 6 wherein the ad ditional layer of material is also in part in tubular form.

8. An article such as defined by claim 3 wherein the continuation is provided with means for attaching the member thereto.

9. A television picture tube comprising an envelope, said envelope comprising a glass viewing panel, a glass funnel, said panel and said funnel having endless sealing surfaces facing one another, and an assembly interposed between such sealing surfaces, said assembly comprising a pair of endless metal strip elements, each such element comprising a relatively thick portion and an associated relatively thin portion extending outwardly therefrom, the relatively thick portion of one of said elements being butt-sealed to the sealing surface of the panel and the relatively thick portion of the other of said elements being butt-sealed to the sealing surface of the funnel, one of the portions of one of the elements having a plurality of spaced inwardly extending projections, the relatively thin portions of the two elements being joined to one another in sealing relation; and a viewing-screen assembly supported on such projections.

10. A television picture tube such as defined by claim 9 which includes a mounting stud on each projection and in which the viewing-screen assembly is mounted on such studs.

11. A television picture tube comprising an envelope, said envelope comprising a glass viewing panel, a glass funnel, said panel and said funnel having endless sealing surfaces facing one another, and an assembly interposed between such sealing surfaces, said assembly comprising a pair of endless metal strip elements, each such element comprising a relatively thick portion and an associated relatively thin portion extending outwardly therefrom, the relatively thick portion of one of said elements being butt-sealed to the sealing surface of the panel and the relatively thick portion of the other of said elements being butt-sealed to the sealing surface of the funnel, one of the portions of one of the elements having an inwardly projecting relatively thin peripheral continuation, the relatively thin portions of the two elements being joined to one another in sealing relation; and a viewing-screen assembly supported on such continuation.

12. A television picture tube such as defined by claim 11 which includes a plurality of spaced mounting studs on the inwardly projecting peripheral continuation and in which the viewing-screen assembly is mounted on such studs.

13. A television picture tube comprising an envelope, said envelope comprising a glass viewing panel, a glass funnel, said panel and said funnel having endless sealing surfaces facing one another, and an assembly interposed between such sealing surfaces, said assembly comprising a pair of endless metal elements, each such. element comprising a relatively thick strip and an associated relatively thin strip, the relatively thin strip being joined to the relatively thick strip in sealing relation and extending outwardly therefrom the relatively thick strip of one of said elements being butt-sealed to the sealing surface of the panel and the relatively thick strip of the other of said elements being butt-sealed to the sealing surface of the funnel, the relatively thin strip of the element sealed to the funnel having an inwardly projecting peripheral continuation, the relatively thin strips of the two elements being joined to one another in sealing relation; and a viewing-screen assembly supported on such continuation.

14. A television picture tube such as defined by claim 13 which includes a plurality of spaced mounting studs on the inwardly projecting peripheral continuation and in which the viewing-screen assembly is mounted on such studs.

References Cited in the file of this patent UNITED STATES PATENTS 2,423,006 Gibson June 24, 1947 2,527,587 Srnyth Oct. 31, 1950 2,635,205 Olson Apr. 14, 1953 2,650,683 McPhee et al. Sept. 1, 1953