US3732450A

US3732450A - Electron gun assembly having cathodes insulatively mounted in metallic plate

Info

Publication number: US3732450A
Application number: US00173697A
Authority: US
Inventors: H Mayers
Original assignee: Philco Ford Corp
Current assignee: Space Systems Loral LLC
Priority date: 1971-08-20
Filing date: 1971-08-20
Publication date: 1973-05-08
Anticipated expiration: 1990-05-08

Abstract

For the multi-gun assembly of a cathode ray tube, a unitary cathode mounting plate provided with integral beading spaced, and having three apertures - in either delta or in-line configuration - within which cathode eyelets are glass-frit mounted. Conventional cathode and cathode heater structure is associated with each of the eyelets insulatively secured to the plate by the glass frit.

Description

I United States Patent 1 1 1 1 3,732,459 Mayers 1 1 May 8, 1973 [54] ELECTRON GUN ASSEMBLY HAVING [56] References Cited CATHODES INSULATIVELY MOUNTED IN METALLIC PLATE UNITED STATES PATENTS 2,645,734 7/1953 Rajchman ..313/68 [75 1 Inventor E s: Mayers Hummgdo val 2,957,106 10/1960 Moodey ..313 70 c x 3,244,927 4/1966 Drake et al 1 ..313/270 [73] Assignee: Philco-Ford Corporation, Philadel- 3-443-316 6/1969 Yoshida ct C phia 3,569,768 3 1971 Benda ..313 270 3,575,626 4/1971 Blumenberg ..313/70 C 22 Filed: Aug. 20, 1971 Primar Examiner-Robert Se a1 21 A LN 173,697 y g I pp 0 AttorneyCar] H. Synnestvedt Related US. Application Data [57] ABSTRACT [63] Continuation of Ser. No. 873,361, Nov. 3, 1969,

abandoned. For the multi-gun assembly of a cathode ray tube, a unitary cathode mounting plate provided with integral [52] U.S.Cl. ..313/70 R,313/7OC,313/270 beading spaced, and having three apertures in [51] Int. Cl ..H01j 29/04, HOlj 29/50 either delta or in-line configuration within which [58] Field of Search..' ..313/69, 69 C, 70, cathode eyelets are glass-frit mounted. Conventional 1 Claim, 5 Drawing Figures ELECTRON GUN ASSEMBLY HAVING CATHODES INSULATIVELY MOUNTED IN METALLIC PLATE This application is a continuation of Ser. No. 873,361, filed Nov. 3, 1969, abandoned.

BACKGROUND OF THE INVENTION This invention relates to an electron gun assembly, and is directed especially to improvements in electron gun assemblies of the type used in color cathode ray tubes. 7

In one well known electron gun assembly of the aforementioned type, the cathode structure comprises threeseparate cathode elements assembled on insulative rods. Manufacture of these separate elements, and assembly thereof into the gun structure, is time consuming and involves painstaking alignment procedures.

SUMMARY OF THE INVENTION The present invention is directed to improvement of such cathode structure, looking to improvements in the overall assembly of the gun and simplification of the alignment problems.

In achievement of the foregoing as well as other objectives, the invention contemplates provision of a single cathode plate to serve as support means for the cathode elements of a plural electron gun assembly. Each of the cathode elements is located in an eyelet that is mounted in an aperture in the metal cathode plate by means of glass frit that not only joins the eyelet to the support plate, but also serves as an insulator preventing electrical contact between the eyelet and the plate. In the fabrication of the above described assembly, the cathode support plate and its associated support are fabricated as a single unit, having three apertures for receiving the eyelets. The cathode eyelets are provided with a head of glass frit paste and are pushed through the plate apertures and into position so that the frit occupies the space between the eyelet and the support plate. The subassembled plate and eyelets are placed in a jig and fired to fuse the glass frit. The cathode plate and its associated eyelets are then ready for insertion of the cathode and heater therein, in accordance with conventional practice. The invention contemplates that the cathode arrangement be of either in-line or delta configuration.

The manner in which the foregoing as well as other objectives may best be achieved will be more fully understood from a consideration of the following description taken in light of the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an elevational showing, partly in section and with parts broken away, of a cathode ray tube embodying electron gun structure made in accordance with one aspect of the invention;

FIG. 2 is an enlarged sectional view of apparatus illustrated in FIG. 1, as seen looking generally in the direction of arrows 2-2 applied thereto;

FIG. 3 is a sectional view of a portion of the gun structure illustrated in FIG. 2, as seen looking in the direction of arrows 3-3 applied thereto, and showing further details of the particular cathode structure contemplated by the invention; and

FIGS. 4 and 5 are views similar to FIGS. 2 and 3,'and illustrating a modified embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS With more particular reference to the drawing, and first to FIG. 1, an electron gun assembly 10 made according to the invention is mounted in the neck 11 ofa cathode ray tube having substantial portions broken away for convenience of illustration. Gun assembly 10 includes three individual guns only one of which is shown in FIG. 1, at 12, and each comprising tubular and cupshaped, axially aligned grids on insulative support rods 14 mounted in conventional manner on certain ones of connector pins 15. The grids, or electrodes, are electrically connected to appropriate ones of the terminal pins 15 extending through the base portion of tube neck 11. With reference also to FIGS. 2 and 3, the

guns 12 are disposed in delta array. That is, they are spaced at substantially equal radial distances about the axis of the tube neck 11. The several grids of each gun comprise the control grid 16, accelerating grid 17 and focus grids 18, 18a, 18b, the latter supporting a convergence shield 19 electrically connected by the usual spring snubbers (not shown) to the inside conductive coating of the picture tube.

The gun grids cooperate with one another, with cathodes and cathode heaters therefor, and with several external voltage sources of different values, to produce a high velocity stream of electrons. Such operation is conventional, and need not be discussed in detail for an understanding of the invention.

In especial accordance with the invention, and with further reference to FIGS. 2 and 3, the cathode structure comprises a single cathode plate 21 that supports the three operating cathode elements, there being one such element per gun. Support plate 21 includes three mounting spades 25, each embedded in a correspondingly positioned glass rod 14. The cathode structure further includes three cathode sleeves 20, each disposed in an eyelet 22 mounted in an aperture 23 in plate 21. The sleeves 20 conveniently are capped at their upper ends by an electron emissive material 28 of known type. The lower ends of sleeves 20 flare outwardly into supporting engagement with generally triangularly shaped lower portions of eyelets 22, which arrangement is conventional.

Unlike conventional practice, fused glass frit 24 joins eyelet 22 to support plate 21, the frit also serving in an electrically insulative capacity preventing electrical contact between adjacent operating cathode elements. Advantageously, the plate 21 and its spades 25 are fabricated, using metal stamping techniques, as a single unit having three apertures 23 through which the eyelets 22 extend, and while it has been shown as being substantially flat, plate 21 will be bent slightly to position the cathodes at the gun convergence angle.

In assembly of the cathode structure, a bead of glass frit paste is applied between flange 26 of the cathode eyelets 22 and plate 21, so that the frit paste occupies the space between the eyelet flange 26 and confronting adjacent portions of support plate 21 as the eyelets are urged into position. The elements thus subassembled are then fired to fuse, or mature, the glass frit paste. The cathode plate and sleeve assembly is then available for assembly into the gun structure, and for insertion of the cathode sleeve 20 and associated heater 27 into the eyelets 22, in accordance with conventional practice.

It will be appreciated that the gun assembly, and the required alignment procedures, are greatly simplified by this invention, since it is no longer necessary to maintain three separate cathode assemblies in precise relative alignment with beading the same in the glass rods.

With reference to FIGS. 4 and 5, another embodiment of the invention is shown, which is especially adapted for disposition in single gun structure provided with three cathodes for emitting a like number of beams, i.e. Trinitron type construction. Again, a cathode support plate 30 is provided with three 'integrally formed spades 31 that are embedded in corresponding ones of a like number of insulative support rods 32. Plate 30 comprises three apertures 33 in an in-line array, that is aligned diametrically across the plate. Cathode eyelets 34 are mounted within apertures 33 by the annular bodies of glass frit 35 disposed between eyelet flanges 36 and confronting surfaces of the plate 30. The eyelets 34 receive and support the cathodes 37 with their emissive regions 38 disposed in axial alignment with apertures 39 in the control grid 40, as shown.

It will be understood that, for either embodiment of the invention, the thermal expansion characteristics of the cathode support plate, the cathode eyelets, and the glass frit will be selected so as to be closely matched. For example, the metal elements may comprise an alloy of nickel, such as stainless steel, and the'glass frit may comprise a glass of the kind available under the trademark Corning 7575.

I claim:

1. In cathode ray tube electron gun structure of the type including a plurality of electrically insulative rods supporting a plurality of associated electrode elements including apertured control grid means, improved shielded cathode structure comprising: a unitary metallic cathode mounting plate supported on said rods and having three apertures aligned with corresponding apertures of said control grid means; a metallic cathode eyelet mounted in each of said apertures in said plate, each said eyelethaving a peripheral, transversely extending mounting flange overlying planar surface portions of said plate on the side remote from said grid means, said portions immediately surrounding the apertures therein; and an annular body of fused glass frit interposed between each said eyelet and said plate and between each said mounting flange and the confronting overlain surface portions of said plate, and providing insulative mounting of each said eyelet in said plate, each said eyelet supporting a cathode sleeve having an open end portion and an opposite, walled end portion provided with electron emissive material confronting a corresponding one of said apertures of said control grid means said cathode mounting plate including support spades formed integrally therewith and having portions embedded in said insulative rods.

Claims

1. In cathode ray tube electron gun structure of the type including a plurality of electrically insulative rods supporting a plurality of associated electrode elements including apertured control grid means, improved shielded cathode structure comprising: a unitary metallic cathode mounting plate supported on said rods and having three apertures aligned with corresponding apertures of said control grid means; a metallic cathode eyelet mounted in each of said apertures in said plate, each said eyelet having a peripheral, transversely extending mounting flange overlying planar surface portions of said plate on the side remote from said grid means, said portions immediately surrounding the apertures therein; and an annular body of fused glass frit interposed between each said eyelet and said plate and between each said mounting flange and the confronting overlain surface portions of said plate, and providing insulative mounting of each said eyelet in said plate, each said eyelet supporting a cathode sleeve having an open end portion and an opposite, walled end portion provided with electron emissive material confronting a corresponding one of said apertures of said control grid means said cathode mounting plate including support spades formed integrally therewith and having portions embedded in said insulative rods.