US2536636A

US2536636A - Lead-in conductor for electron discharge devices

Info

Publication number: US2536636A
Application number: US709989A
Authority: US
Inventors: Jr Oliver H Fulton
Original assignee: RCA Corp
Current assignee: RCA Corp
Priority date: 1946-11-15
Filing date: 1946-11-15
Publication date: 1951-01-02
Anticipated expiration: 1968-01-02

Description

Jan. 2, 1951 2,536,636

LEAD-IN CONDUCTOR FOR ELECTRON DISCHARGE DEVICES O. H. FULTON, JR

Filed Nov. 15, 1946 (Ittomeg Patented Jar 1 2, 1951 UNITED STATES PATENT OFFICE LEAD-IN CONDUCTOR FOR ELECTRON DISCHARGE DEVICES Oliver H. Fulton, J12, Montclair, N. J., assignor to Radio Corporation of America, a corporation oi Delaware 10 Claims.

The present invention relates to lead-in com doctors for electron discharge devices and more particularly to lead-in conductors of the type having a relatively rigid portion for sealing through an envelope wall of the device and relatively flexible portion for connection to an e1ectrode within the device.

In devices of the type useful at high frequencies the lead from the input, or control grid elec trode, is frequently taken from the end of the device remote from the base and the lead from the output, or anode electrode, extending from the base of the device, so as to secure the maximum spacing between these leads to avoid undesirable capacity effects therebetween.

The lead taken from the end of the device remote from its base includes in some cases a rigid metallic rod portion adapted to form a glass-to-metal seal with the envelope wall of the device. The lead-in also includes a portion which is more flexible than the rod portion and which is designed for connection to an electrode of the device, for example, the control grid.

In practice, as heretofore followed, the electrode mount of the device is usually first prepared and includes the lead-in conductor for use at the end of the device remote from the base. The resilient portion of the lead-in is usually fastened as by welding to one of the electrodes, and the rod portion thereof is disposed coaxiall with respect to the mount. The envelope blank is provided with an aperture at its' end remote from the base, through which the rod portion of the lead-in is extended when the mount is fixed in position within the envelope prior to scaling the lead in the wall of the envelope.

Several problems are associated with this practice. One of these problems concerns the need for maintaining the rod portion of the lead-in in coaxial relation to the mount when it is threaded into the envelope aperture referred to. The means for maintaining the rod portion or" the'lead-in' in this relation is also required to be sufii'ciently flexible so that any stresses applied to the lead-in laterally can be absorbed by such means and not transmitted to the electrode served thereby. Such stresses might easily occur on insertion of the mount in the envelope due to improper line-up of the envelope and mount,

and thermal expansion of the parts involved.

In addition, there are problems created by the inherent structure of lead-in of the types discussed. For instance, the provision of a flexible portion of the lead-in has involved a reduction in the cross-section area of this portion to such extent that it possesses very little heat conducting ability. Furthermore, the usual practice of forming this flexible portion of the lead-in in the shape of a pig tail to increase its flexibility, results in undesirable inductance effects at high frequencies and extends the length of the path of high frequency currents to the electrode served by the lead-in.

It is an object of my invention to provide an improved lead-in construction for an electron discharge device particularly suitable for use at high frequencies.

It is another object to provide a lead-in for an electron discharge device which is substantially free from the objections enumerated in the problems referred to.

It is a further object to reconcile the mutually opposed structural considerations of a lead-in for an electron discharge device to provide a device in which the lead-in contributes to convenience of assembly and good operation of the device.

Another object is to provide a lead-in for an electron discharge device which possesses desired physical characteristics for contributing facility to assembly, assurance of maintenance of desired spacings, and good heat conductivity as well as desired electrical characteristics of short paths for high frequency currents and reduction of inductive effects therein.

An additional object is to provide a method of making a lead-in for an electron discharge device having the advantages referred to in the preceding object.

These objects, as well as others which will suggest themselves as this description proceeds, are attained according to my invention by a novel structure, and method of making, a lead-in conductor.

While the invention itself is pointed out with parti ularity in the appended claims, it will be best understood from a detailed description of an embodiment thereof presented solely for illustrative purposes, taken in connection with the appended drawing. In the drawing to which refence is now made,

Figure 1 is an elevation of an electron discharge device with parts cut away to more clearly depict novel lead-in conductor;

Figure 2 is a transverse section along line 22 of Figure l and shows the manner in which the flexible portion of the conductor is connected to the rigid portion thereof, and the ease with which the arms of the flexible portion may be connected to the projecting portions of the two side rods of a grid;

Figure 3 shows a plan view, partly in section, of'a step in my method of manufacture wherein the rigid portion of my conductor is attached to the flexible portion thereof in transverse and substantiall line engagement therewith;

Figure 4 shows another step in my novel method wherein the rigid portion of the conductor has been given a twist coaxially in a clockwise direction; and

Figure 5 shows a side view of my completed lead-in conductor.

Referring now to the drawing in more detail, there is shown in Figurel a pentode of the miniature tube type having a glass envelope is including a glass base i! enclosing an electrode mount including electrodes comprising an anode I2, suppressor grid i3, i3a, shielding grid i l, control grid l5 and cathode it, supported on insulating spacer plates ll, iii. The electrodes are connected to suitable leads one of which includes lead is passing through the envelope of the end thereof remote from the base, and the other of which includes base contact pins 29 passing through base ii. Lead it serves the input or control grid electrode i5 and the leads 2B serve the other electrodes including the anode 12 or output electrode of the pentode. This arrangement results in a maximum spacing of the leads to the input and output electrodes for reduction of undesired electrical effects therebetween.

According to the invention, lead 49 is con structed of two parts comprising the comparatively rigid metallic rod l9 and the relatively flexible metallic ribbon 2!. The ribbon 2i embraces an end portion of the rod iii in a fixed and part frictional engagement at sub stantially a longitudinally middle portion of the ribbon to provide two arms. The wider surfaces of ribbon 2i lie in planes parallel to the longi-- tudinal axis of rod [9. The

ends

22, 23 of the arms of ribbon 2i are bent in parallel relationship to rod IS without disturbing the parallel relationships of the wider surfaces thereof to the longitudinal axis of rod i9 and are suitably connected to side rods [5 of the control grid which are spaced apart from each other. The rod is is sealed through the envelope at the end thereof remote from the base H. Although the cross sectional form of ribbon 2! is relatively narrow, this form is sufficiently long to provide a cross sectional area substantially equal to that of the rod l9.

Figure 2 shows more clearly the engagement between ribbon 2i and rod [9. Ribbon 2i is fixedly connected to rod is at portion 24, as by welding, which is substantially linear across the ribbon and parallel to the rod. The fixed connection between rod is and ribbon 2!, therefore, includes relatively small surfaces of these memhere. The remainder and larger portion of surface engagement between rod is and ribbon 2! is not fixed other than by friction between the members and the elasticity of the ribbon.

These structural characteristics of my novel lead-in contribute advantages both during assembly and subsequent operation of an electron discharge device in which they are incorporated.

Thus, during assembly of the device and particularly during the step of extending one of the lead-ins through the aperture in the envelope remote from its base, it is necessary to take care that no strains are placed on the mount or on any electrode thereof. Such strains may result from failure of the lead-in to properly register with the envelope aperture and the use of force to accomplish such registering relationship. This failure to register may be occasioned by faulty line-up which requires a lateral displacement of the lead-in as a remedy therefor. The structure of my novel lead-in permits easy lateral displacement thereof with respect to the mount so that the desired line-up of the leadin and the mount may be effected Without harmful strains on the electrode connected to the lead-in. As will be apparent from Figure 2, lateral strains between rod is and grid !5 can easily be absorbed by the ribbon 2! since it is out of alignment with the direction of such strains and receives them normal to its wider surfaces.

An additional feature of my novel lead-in which facilitates assembly of the device in which it is employed a desired rigidity of the leadin structure axially of the electrode mount. This rigidity is desirable for convenience in extending a portion of the lead-in through the envelope aperture referred to. However, while the structure is sufficiently rigid to prevent axial contraction of the lead-in during normal conditions of assembly, it possesses sufiicient flexibility axially to prevent damage to the mount in the event unusual strains should be encountered. This axial flexib'lity of my lead-in structure wh iicient to disturb the desired a. a1 1' ty rere ed to, results from the novel manner joining th rod is thereof to the ribbJn 25 in a only a portion of which represents a fixed connec ion between these members of the lead-in.

In addition to proving advantageous in the assembly of an electron discharge device, my novel lead-in also contributes to good operation of the device. Thus any lateral strains on the lead-=in within the envelope during operation of the evice arising, for example, as the result of thermal conditions, will be absorbed by ribbon 2i and will not be transmitted to the electrode connect;d thereto. Also if the grid side rods expand due to heat the lead will flex and not distort the grid. in addition, the fact that the cross-sectional area of the ribbon 2i is substantially equal to that of the rod it results in heat conducting qualities of the lead-in which are unimpaired by the flexible character of the ribbon 2E. Moreover, the provision of two

arms

22, 23 on the ribbon 2% permits connection of the leadin to two spaced portions of an electrode to further contribute to heat dissipation from the electrode. The relatively large surface engagement between the ribbon 2i and rod It further aids in heat oonduc tion from the electrode associated with the lead-1n. Furthzrmore, since no portion of the lead-in is coiled, the generation of undesired inductance effects is prevented and a shortening of the electrical path through the lead-in is effected.

Figures 3, 4 and 5 show steps in my novel method of making the lead-in of my invention. In Figure 3 ribbon 24 is shown fastened as by welding at 2 3 to rod it. Ribbon 2! is then held against torsional movement as by chucks 25, 26, while rod I9 is given an axial twist in the direction of the arrow. A transverse portion of the rod I9 is then engaged in a fold by ribbon 2|, the fold engagement being faci'itated by the fixed connection 25, which is substantiahy linear axially of rod is. The resultant structure is shown in Figure 4. Thereafter, the ends 22, 23 of the arms of ribbon 2| are folded as shown in Figure 5 8 so that they are parallel to rod l9 and have a side edge facing this rod. The lead-in may then be connected to spaced portions of an electrode, such as the control grid side rods l as shown in Figure 1 to complete the electrode mount for placement within an envelope.

While an embodiment of my invention has been described, my invention is not to be regarded as limited to the particular features thereof. This embodiment may be subjected to many modifications by persons skilled in the art without departing from the invention as pointed out in the appended claims.

I claim:

1. A lead-in conductor for an electron discharge device comprising a flexible portion and a rigid portion, said rigid portion comprising a metallic rod, said flexible portion comprising a metallic band, said band being fixedly connected to said rod adjacent one end thereof in substantially a straight line contact transversely of said band, and frictionally and resiliently connected thereto by surface contact, said flexible portion including oppositely extending arms having end portions parallel to said rod for connection to spacedapart portions of an electrode.

2. Lead-in conductor for an electron discharge device including a rod for sealing through the glass wall of said device and a metallic band for connection to spaced apart portions of an electrode, said band being frictionally connected to said rod by embracing a transverse portion of said rod in a fold, and fixedly connected to said rod at a portion of said fold, said fold being transversely of said band, said band having end portions bent at right angles with respect to said band and lying in planes parallel to said band.

3. A lead-in for an electron discharge device comprising a conducting rod to be sealed through the envelope of said device, and a flexible ribbon conductor mounted transversely of the rod at one end thereof, said ribbon conductor having its wider surfaces lying parallel to said rod and having a loop intermediate its ends encompassing and contacting said rod, said ribbon being fixed to said rod along a line longitudinally of said rod, the ends of said ribbon being folded over to be parallel to said rod and to engage spaced portions of an electrode of said device.

4. A lead-in for an electron discharge device comprising a conducting rod and a flexible ribbon conductor having a portion intermediate its ends wrapped transversely around an end portion of said rod for engaging more than 180 degrees but less than the whole of the periphery of said rod, said ribbon conductor having end portions extending from different sides of said rod.

5. A lead-in for an electron discharge device comprising a conducting rod and a flexible ribbon, said ribbon having an intermediate portion wrapped around an end portion of said rod and engaging more than 180 degrees of the periphery of said rod, whereby the two end portions of said ribbon extend laterally from said rod, one of said two end portions being folded upon itself for extending from a different side of said rod than the other of said two end portions, whereby said two end portions are adapted to be connected to displaced portions of an electrode within said device.

6. A lead-in for an electron discharge device comprising a rigid rod and a flexible ribbon, said ribbon at an intermediate portion thereof being wound transversely of an end portion of said rod to engage more than half the periphery of said rod, whereby the two end portions of said ribbon extend laterally from said rod, one of said two end portions being bent to provide a fold upon itself adjacent said rod for extending from said rod in a different direction from the other of said two end portions, said ribbon being fixed to said rod adjacent said fold, whereby said lead-in is responsive to forces normal to said rod for accommodating said lead-in to an electrode variably spaced laterally with respect to said rod.

7. A lead-in for an electron discharge device comprising a rigid rod fixed to the envelope of said device in a seal and a flexible ribbon fixed to said rod and to spaced portions of an electrode, said ribbon including two arms extending from different sides of said rod, each of said arms includin a plurality of folds between said rod and said electrode for permitting displacement of said electrode from said rod without impairing said seal and the structure of said electrode.

8. An electron discharge device including a grid having two spaced side rods, and a lead-in for said grid connected to said side rods, said leadin comprising a rigid rod fixed to the envelope of said device in a seal, and a flexible ribbon mounted intermediate its ends on said rod, the ends of said ribbon being fixed to said side rods, and two folds in said ribbon intermediate said rod and each of said side rods for absorbing forces resulting from misalignment of said grid with respect to said rod without impairin said seal and said grid.

9. A lead-in for an electron discharge device comprising a rigid conductor for sealing through the envelope of said device, and a flexible ribbon fixed intermediate its ends to said rod, the ends of said ribbon being adapted to be connected to spaced portions of an electrode within said device, said ribbon being folded along two angularly disposed lines between said rod and each of said spaced portions for providing a flexible connection between said rod and said electrode.

10. A lead-in for an electron discharge device comprising a, rigid conductor for sealin through the envelope of said device, and a flexible ribbon fixed to said rod and to an electrode within said device, said ribbon having plurality of folds therein for providing a resilient connection between said rigid conductor and said electrode.

OLIVER H. FULTON, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS