US3396298A

US3396298A - Series connected heater element for multiple electron gun subassembly

Info

Publication number: US3396298A
Application number: US591166A
Authority: US
Inventors: Alan T Kuryla
Original assignee: Sylvania Electric Products Inc
Current assignee: GTE Sylvania Inc
Priority date: 1966-11-01
Filing date: 1966-11-01
Publication date: 1968-08-06
Anticipated expiration: 1985-08-06
Also published as: GB1176255A

Description

Aug. 6, 1968 A. T. KURYL. 3,396,298

SERIES CONNECTED HEATER ELEM T FOR MULTIPLE ELECTRON GUN SUBASSEMBLY Filed Nov. 1. 1966 IN VENT OR.

AAA/v I KURYM W3 7 /z57 BY a/wzjfiw/ F 5 ATTORNZY United States Patent 3,396,298 SERIES CONNECTED HEATER ELEMENT FOR MULTIPLE ELECTRON GUN SUBASSEMBLY Alan T. Kuryla, Geneva, N.Y., assignor to Sylvania Electric Products Inc., a corporation of Delaware Filed Nov. 1, 1966, Ser. No. 591,166 Claims. (Cl. 31370) ABSTRACT OF THE DISCLOSURE A series connection of the heater elements of a threeelectron gun subassembly is provided by preforming a heater element connecting strap having three elongated protuberances, each defining a removable area. The connecting strap is secured to insulating support rods of the gun assembly so that each protuberance is supported in a fixed spatial relation to one of the cathode elements to permit the connection of the respective heater elements across the protuberance such that a series connection is completed when the removable area of each protuberance is cut out.

This invention relates generally to electron guns and more particularly to improved means for providing a series connection of the heater elements in tubes having multiple electron guns. Although having general application, the invention finds particular utility in color picture tubes of the three-gun type.

In multiple electron gun cathode ray tubes, the heater current is supplied to the tube by way of the two stem leads which are in turn connected to the heater elements of the respective electron guns. According to presently accepted practice, a number of straps are mounted on insulating support rods within the tube and each strap provides a connection between the ends of heater elements in adjacent electron guns or between one end of a heater element and an input stem lead. Because of the number of straps involved, the mounting operation is relatively time consuming and great care must be exercised in the mounting of the straps to assure proper alignment of the straps with the location of the ends of the heater elements. If a strap is improperly mounted, the heater element connected thereto may be distorted and thereby affect the operating characteristics of its associated electron gun. It it also possible that an improper mounting may result in a shorting of the heater element. These difliculties are particularly troublesome in color television picture tubes where the failure of any one electron gun effectively renders the tube inoperative.

Accordingly, it is an object of the present invention to provide a simplified, more reliable and economical heater element mounting structure for multiple electron gun cathode ray tubes.

The foregoing and other objects and advantages are achieved in one aspect of the invention which utilizes a single preformed connecting strap which can be positively placed in and fastened to the insulating support rods of the electron gun structure. After the strap is fastened in place, such as by Welding, voids are cut in the strap at predetermined positions and the ends of the respective heater elements are suitably connected across the voids, thereby effecting the desired series connection of the heater elements.

For a better understanding of the present invention, together with other and further objects, advantages and capabilities thereof, reference is made to the following disclosure and appended claims in connection with the accompanying drawings, in which:

FIG. 1 is a partial perspective view of -a three electron gun structure embodying the invention;

"ice

FIGS. 2 and 3 are end elevation views of alternate embodiments of the invention for three electron gun structures;

FIG. 4 is a partial side view of a preformed heater element connecting straps according to the invention;

FIG. 5 is a partial perspective view of an alternate embodiment of a preformed heater element connecting strap according to the invention; and

FIG. 6 is a partial end view of an alternate configuration of a preformed heater element connecting strap according to the invention.

For simplicity and ease of understanding, the invention will be described in connection with a three-gun structure, such as used in a color picture tube. However, it will be apparent that the disclosed concept is applicable to any multiple electron gun structure.

Referring to FIG. 1, there is shown the envelope 11 of a tube within which are contained three insulating support rods 13, 14, and 15. Mounted in the envelope 11 are cylindrical cathode elements 17, 18, and 19 within each of which is contained a respective heater element, only the ends of which are shown. The cylindrical cathode elements are connected to the insulating support rods 13, 14, and 15 by suitable cathode mounting straps (not shown). The ends of the heater elements are supported by four connecting

straps

23, 24, 25, and 26, which are, in turn, connected to the support rods 13, 14, and 15 by mounting

posts

29, 30, 31, and 32, respectively. Connecting members 33 and 35 provide connections between straps 26 and 23, respectively, and the heater element stem leads (not shown). While the connecting straps 23-26 appear as separate elements in the completed structure, they are derived from a single preformed strap to be later described.

FIG. 2 shows the manner in which the invention provides a supporting series connection for the heater ele ments '41, 42 and 43 of

cathodes

45, 46, and 47, respectively, in a three-electron gun structure. A preformed connecting strap 49 having three elongated protuberances 51, 52 and 53, suitably spaced along its perimeter is mounted in the gun structure by affixing the strap 49 to mounting

posts

55, 56, 57 and 58 which are embedded in glass support rods 60, 61 and 62. After the connecting strap 49 is thus firmly mounted in the gun structure, the center portions of the elongated protuberances 51-53 are cut-out to provide discontinuities in the connecting strap. The cutout of the center portion of the elongated protuberances can be done in any conventional manner. For example, it can be performed manually such as by an operator using a pair of diagonal pliers or metal cutters. Furthermore, because of the close tolerances possible, the cut-out operation could be fully automated. The ends of the

heater elements

41, 42 and 43 are connected to the elongated protuberances 51, 52 and 53, respectively, such that each heater element is connected across the discontinuity in its respective elongated protuberance, thereby forming the desired series connection of the heater elements in the gun structure.

Leads

64 and 65 affixed, respectively, to mounting

posts

57 and 58 are connected to the input stem leads (not shown) supplying heater current.

The advantages of providing series heaters connections in this manner will be readily apparent to those skilled in the art. Since the single connecting strap is preformed, its dimensions can be closely controlled such that when placed in the gun structure, the elongated protuberances are in positive registration with the cathode elements, thereby permitting accurate controlled placement of the heater element and substantially reducing the possibility of gun failure resulting from a shorted or distorted heater element. Furthermore, because the dimensions of the connecting strap 49 are controlled, thereby assuring positive placement with proper registration in the gun structure,

the steps of mounting the connecting strap in the gun structure and forming the series connection are less likely to result in faults due to human error.

It will be appreciated that the connecting strap can be formed in a variety of shapes, depending upon particular requirements or preferences. For example, the preformed connecting strap 79 shown in FIG. 3 is generally triangular in shape with the side of the strap connected via

mounting posts

85, 86, 87 and 88 to the

glass support rods

90, 91 and 92. The

corners

95, 96 and 97 of the strap 79 are flattened to provide proper registration of the strap over the cathode elements and to facilitate the location of the cut-outs necessary to provide the discontinuities across which the

heater elements

101, 102 and 103, respectively, are connected.

As illustrated in FIG. 4, it may be desirable to cut out a portion 107 in the center of the elongated protuberance 109 of the strap 110 during the forming operation. Then, when the strap 110 is mounted in the gun structure, less cutting force is required to remove the remaining center 111 of the elongated protuberance 109 in providing the discontinuity across which the heater element is to be connected, and the possibility of distorting the strap 110 during the cutting operation is reduced.

According to a further embodiment of the invention, as disclosed in FIG. 5, the preformed connecting strap 115 may have one or more mounting tabs 117 suitably positioned along one edge such that when placed in the electron gun structure, the mounting tab is in registration with a respective mounting post 119 which is embedded in a glass support rod 121. Utilizing this configuration, the mounting tabs will support the connecting strap in a proper position in the electron gun structure prior to the welding operation which secures the connecting strap to the mounting posts.

As shown in FIG. 6, the elongated protuberance 125 may be formed to extend inward from the circumference of the connection strap 127. Also, the connecting strap 127 may be constructed from material having a substantially circular cross-section, i.e., wire, rather than from ribbon stock material as previously shown. The particular choice of strap material and strap configuration may, therefore, vary depending upon design limitations and structural requirements without departing from the scope of the present invention.

Thus, there is provided improved means for interconnecting the heater elements in a multiple electron gun structure. The utilization of the preformed connecting strap having controlled dimensions assures the proper mounting in the gun structure in registration with the cathode elements, thereby facilitating the correct place ment of the heater elements within the cathode elements. Since the possibility of human error is substantially reduced, the resultant structure is inherently more reliable and less likely to fail. Also, the controlled dimensions of the preformed connecting strap, make it possible to automate part of the heater element mounting process. For example, by machine process it is now possible to insert the preformed connecting strap in the electron gun subassembly, weld the strap to the mounting posts and cut out the desired portions of the elongated protuberances prior to the insertion of the cathode heater elements, thereby providing a more economical gun structure.

While there have been shown and described what are at present considered the preferred embodiments of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the scope of the invention as defined by the appended claims.

What is claimed is:

1. A three-electrongun subassembly comprising:

three cylindrical cathode elements disposed a relatively equal distance apart, thereby defining the corners of a triangle within said subassembly;

three insulating support rods each disposed adjacent one side of said triangle;

a preformed heater element connecting strap having two ends and having three elongated protuberances; and

means for securing said strap to said insulating support rods such that the three elongated protuberances of said strap are positioned, respectively, adjacent to said three cathode elements.

2. The invention according to claim 1, wherein the shape of said connecting strap is circular with the two ends of said strap adjacent to, but not touching, each other and wherein said means for securing said strap to said insulating support rods comprise:

first and second support members connected between the two ends of said connecting strap, respectively,

and a first one of said three support rods; and

third and fourth support members connected between said remaining two support rods, respectively, and

sides of said connecting strap adjacent thereto. 3. The invention according to claim 1, wherein the shape of said connecting strap is triangular with the two ends of said strap adjacent to, but not touching each other, and wherein said means mounting said connecting strap to said support rods comprise:

first and second support members connected between the two ends of said connecting strap, respectively, and one of said three support rods; and

third and fourth support members connected between said two remaining support rods, respectively, and the sides of said connecting strap adjacent thereto.

4. The invention according to claim 1 wherein said preformed heater element connecting strap additionally comprises a plurality of mounting tabs suitably spaced along said strap such that each of said mounting tabs is adapted to be positioned within said subassembly adjacent to one of said insulating support rods.

5. A multiple electron gun subassembly comprising:

a plurality of cylindrical cathode elements disposed a relatively equal distance apart;

a preformed heater element connecting strap having two ends and a plurality of elongated protuberances;

a plurality of insulating support rods; and

means for securing said strap to said plurality of insulating support rods such that the plurality of elongated protuberances of said strap are positioned, respectively, adjacent to said plurality of cathode elements.

References Cited UNITED STATES PATENTS 5/1964 Brown 313-271 3/1966 Brown 3l3271