US2778968A - Electrode cage for electron discharge devices - Google Patents

Description

2 Sheeii's-Sheec l 5 M mm ll i m n Jan. 22, 1957 F. J. PILAS ET AL ELECTRODE CAGE FOR ELECTRON DISCHARGE DEVICES Filed May 26, 1951 I MW Jan. 22, 1957 F. J. PILAS ET AL ELECTRODE CAGE FOR ELECTRON DISCHARGE DEVICES 2 Sheets-Sheet 2 Filed May 26. 1951 llWi/YI'ORJ Hw /r J Pa: POYAI VVOZAE- m0 JO/777. C/m 3) WW ORNEY United States Patent ELECTRODE CAGE FOR ELECTRON DISCHARGE DEVICES Frank J. Piias, Kearny, Roy K. Wolke, Maplewood, and

John A. Chase, Nutley, N. J., assignors to Radio Corporation of America, a corporation of Delaware Application May 26, 1951, Serial No. 228,386 7 Claims. (Cl. 313-261) The present invention relates to mount assemblies for electron tubes and more particularly to an electrode cage including an insulating spacer plate of novel construction for providing an improved electrode cage. I

Accordingly, it is an important object of the invention to provide an improved electrode cage for improving the operation of an electron discharge device in which it is used.

a A further object is to provide an improved insulating spacer plate for facilitating assembly of an electrode ca e.

Another object is to provide an electron discharge device wherein current leakage between electrodes is reduced.

A further object is to provide an insulating spacer plate having a leakage slot disposed across the area of maximum current or charge concentration on the plate, for reducing current leakage between electrodes.

Another object is to provide an electrode cage including a spacer plate and wherein electrodes are more firmly engaged by the plate to prevent relative movement between the electrodes.

A further object is to provide an insulating spacer plate that includes portions flexed into engagement with electrodes for continuously fixing the electrodes against relative movement.

Another object is to provide an improved insulating spacer plate having apertures for receiving end portions of electrodes and including flexible tongues adjacent the apertures for facilitating threading said end portions through the apertures, and for forcibly engaging said end portions when threaded through said apertures for firmly holding said electrodes against relative movement.

A further object is to provide a closed electrode cage wherein visual communication with the interior of said cage is afforded through said spacer plate.

Another object is to provide a spacer plate for supporting a thermionic cathode with reduced heat transfer from the cathode to the plate.

Briefly considered, there is provided according to the inyention a novel insulating spacer plate, made of a material such as mica, which contribute to an improved electron tube cage and to an advantageous method of assembling components of the cage.

Structurally, the improved spacer plate of the invention comprises a flat wafer or disc having apertures therein for receiving end portions of electrodes, and a plurality of slots of novel design communicating with the apertures referred to.

The slots accomplish several purposes. They form tongues or flexible segments in the spacer plate defining the apertures referred to. On extension of the electrode end portions into the apertures, the tongues or segments are deflected in response to the force of an entering electrode end portion. This deflection of the tongues results in the formation of a tunnel for receiving the end portions referred to, thus facilitating a mounting operation. The deflection also results in an enlargement of the apertures, so that the apertures defined by unflexed tongues may be smaller than the transverse dimensions of the electrode end portions. After extension of the electrodesin such smaller apertures, therefore, the tongues referred to will remain flexed .and provide a continuing force for fixing the electrodes in the spacer plate.

Additional purposes accomplished by the slots in the novel spacer plate of the invention are to reduce heat transfer from a heated cathode to a spacer plate, permit use of an improved jig for facilitating the mounting of electrodes on the spacer plate, reduce leakage between electrodes, and to permit visual inspection of the interior of a cage including the spacer plate referred to.

Further objects and advantages of the invention will become manifest as the present description proceeds.v

Referring now to the drawing for a better understanding of the invention,

Figure 1 shows an exploded elevation of parts included in the electrode cage of one type of electron discharge device;

Figure 2 is a side view of an electrode cage assembled from the parts shown in Figure 1;

Figure 3 is a plan view of the novel insulating spacer plate of the invention that may be used in the cage shown in Figure 2;

Figure 4 is a sectional elevation of a jig that may be used in mounting the parts shown in Figure 1 to form a cage and illustrates the substantial contribution of the novel spacer plate of the invention to an improved mounting operation; I

Figure 5 is arsectional elevation of another form of jig that may be used advantageously in forming a cage from parts including the improved spacer plate of the invention;

Figure 6 is an enlarged partly sectional view along the line 6--6 of Figure 5 and shows one group of funnelling fingers of the jig in relation to the structure of the spacer plate of the invention;

Figure 7 is an enlarged partly sectioned View along the line 77 of Figure 5 and shows another group of funnelling fingers of the jig; and

Figure 8 is a plan view of an electrode cage including a cathode, a grid of an anode and wherein visual inspection of the grid is afforded through the novel spacer plate ofthe invention.

Referring now to the drawing in more detail, there is shown in Figure 1 thereof, component of one type of electrode cage in which the spacer plate of the invention finds particular utility. The parts referred to comprise a cathode sleeve It), an anode 11 having side wings 12, 13 defining passageways for receiving anode support rods 14, 15. The cathode sleeve and anode referred to are supported between spacer plate 16, 17 which have aper tures'for receiving end portions of the cathode sleeve and the anode support rods. The electrode cage formed of these parts is shown in Figure 2 and is adapted to be used in a diode type of electron tube.

According to the invention, one or both of the spacer plates 16, 17, which may be made of an insulating material such as mica, are provided with tongues or segments defining slots and electrode-receiving aperturesor passageways as shown in Figure 3. The aperture 18 is adapted to receive cathode sleeve 10 and the apertures 19, 29 are adapted to receive the anode support rods 14, 15.

The aperture 18 is defined by segments 21, 22, 23, 24. The segments referred to also define slots 25, 26, 27, 28.

The segments constitute tongues integral with the spacer plate and flexible by bending along straight lines indicated by dotted lines, in response to the force exerted on the tongues by a cathode sleeve entering the aperture 18.

Each of the apertures 19, 20 for receiving anode Supgreases port rods 14, is defined by segments 29, 2.0, 31, 32. Slots 33, 34, 35, 36 communicating with the apertures 19, are also defined by the segments referred to. The segments mentioned are integral with the spacer plate and areflexible along straight'lines shown by dotted lines in response to the thrust thereon of anode support rods 14, 15, when the same are extended into apertures 19, 2h.

The fiexure of the segments or tongues defining the apertures 18, 19' and 26, causes them to assume a position in which they form a partial funnel. This partial funnel not only guides electrode end portions into the apertures referred to but also serves to widen the apertures. This last mentioned feature is advantageous in that the apertures 18, 19, 2%" may be made slightly smaller than the cross-sections of the electrode end portions to be received therein to cause the segments defining the apertures to apply a continuing force on the end portions referred to after the electrodes are mounted on the plate, to thereby provide a firm engagement between the spacer plate and electrodes. Relative movement between the spacer plate and electrodes, is therefore restrained, resulting in improved operation of an electron tube in which the spacer plate of the invention is used.

For mounting the electrodes referred to on a spacer plate according to the invention, use may be made of a novel mounting jig 37 shown in Figure 4. The upper surface of the jig is provided with cavities 38, 39, 40 defined by edges adapted to be disposed in substantial registry with the dotted lines along which the segments or tongues defining the apertures 18, 19 20 flex, as shown in Figure 3. The jig includes two locating lugs, one of which is shown at 41 in Figure 4, for engaging apertures 42, 43 shown in Figure 3 to properly register the dotted line portions of the plate with the edges of cavities 38, 39, 40. The bottoms 44, 45, 46 of the cavities referred to serve as stops for the electrode end portions to be extended into the apertures 18, 19, 20. The bottoms of cavities 38 and 40. are lower than the bottom of cavity 39 to permit adjacent ends of the anode support rods 14, 15 to extend farther from the plate 16 than the adjacent end of the cathode sleeve 1%. The jig is also provided with -a mandrel 47 on which the cathode sleeve 10 is adapted to be threaded for registry with the aperture 18 in the spacer plate. The bottom 45 of cavity 39 may be raised or lowered by movement of shaft 48, the upper surface of which forms the cavity bottom 45. The shaft 43 may be locked in desired position by lock screw 49.

As shown in Figure 4, when the anode support rods 14, 15 and the cathode sleeve 10 is urged into apertures 18, 19, 24 of the spacer plate 16, the segments defining the apertures flex to form a funnel-like structure. If any of they electrodes is improperly registered with any of the appropriate apertures referred to, it is urged into such registry by the sloping surfaces of the segments forming the funnel-like structure. This facilitates a mounting operation and renders automatic mounting procedures practicable. It also makes feasible a continuing engagement between the electrodes and the spacer plate resulting from a force exerted by the flexed segments on the electrodes. This last mentioned advantage requires that the apertures 18, 19, 2G in the spacer plate be slightly smaller than a cross-section of the electrode portions received therein.

The spacer plate of the invention is also adapted for use in a mounting operation during which the segments defining the apertures 13, 19, 21 therein are not flexed. A novel jig 50 for use in this type of operation is shown in Figure 5. This jig is similar in some respects to jig 37 shown in Figure 4. For example, it has cavities 51, 52, 53 in its upper surface, the cavities having bottoms 54, 55, 56 serving as stops for electrodes to be mounted. The bottom 55 is formed by the upper end surface of an adjustable shaft 57 and the shaft referred to is fixed after adjustment by lock screw 58.

However, jig 50 differs from jig 37, in that, the cavities 51, 52, 53 therein have transverse dimensions substan- 4. tially equal to the cross-sections of end portions of electrodes to bereceived therein. The edges of the cavities are not therefore in registry; with the dotted lines shown on the spacer plate in Figure 3.

To facilitate extension of the electrodes into the apertures 18, 19, 2b in the spacer plate, without flexing the segments thereof, the jig 50- is provided with a plurality of fingers or risers 59, 60, 61, 62 around cavity 52 as shown in Figure 6, having bevelled sides 63, 64, 65, 66 for forming a funnel-like structure for guiding cathode sleeve 10 into aperture 18 in the spacer plate. Around each of the cavities 54, 56 are also disposed a plurality of risers 67, 68, 69, 70 as shown in Figure 7, having bevelled sides '71, 72, 73,774 forming funnel like structures for guiding the anode side rods 14, 15 into apertures 19, 20 in the spacer plate.

The novel spacer plate of the invention renders the advantageous jig shown in Figure 5 feasible. The slots '75, 76, 25-, 26, 27 and 28 in the spacer plate permit extension of the risers in the jig through the plate, to provide the funnel-like structure referred to for guiding the cathode sleeve 10 into aperture 18. The slots 33, 34, 35, 36 adjacent each of the apertures 19, 20 in like manner permit extension through the plate of risers 67, 68, 69, 70 for guiding the anode side rods 14, 15 into apertures 19, 20.

Each of the mounting modes shown in Figures 4 and 5 has distinct advantages. For example, when the spacer plate is made offlexible material such as mica, the mount ing procedure shown in Figure 4 has particular advantages in that it both provides a guide for the electrodes into the spacer apertures, and also assures a subsequent firm engagement between the spacer plate and the electrodes. However, Where the spacer plate is made of a material such as ceramic that is-incapable of fiexure without breaking, the novel spacer plate of the invention permits use of the advantageous jig of Figure 5 for guiding the electrodes into the apertures in the spacer plate.

In addition to facilitating the mounting of electrodes, the spacer plate of the invention has substantial value in reducing current leakage between electrodes in a tube in which it is used. Current leakage usually first manifests itself in the build-up of an appreciable charge adjacent an electrode constituting an electron source, such as a cathode. This charge when of suflicient magnitude is attracted by an adjacent and more positive electrode, such as an anode or grid. One way of reducing current leakage in the past has been to provide slots in spacer plates between electrodes involved in the leakage. However, it has not been feasible heretofore to disposed the slots in the region of maximum charge due to inherent difliculties presented by the spacer plates. One of these difficulties has been occasioned by the fact that a limitation is imposed as to the closeness of spacing permitted between two adjacent apertures in the plate, such as the cathode aperture and a leakage slot. When the plate is made of mica, it has been necessary to space the slot from the cathode aperture a distance no less than the thickness of the plate. The reason for this is twofold; If the distance between adjacent apertures is less than the thickness of the plate, the bridge between the apertures will disintegrate as a result of flocculation. Furthermore, it is difficult to provide suitable dies for forming apertures that are closer than the thickness of the plate. Such dies require precision techniques of a high order, and unavoidable wear in use will modify spacings originally determined. As a result, leakage slots heretofore used have been deficient in their control of current leakage, predominantly because they could not be disposed close enough to a cathode so as to traverse the region of maximum current leakage.

The spacer plate according to the invention includes a structure that disposes a leakage slot across the region of maximum normal current leakage adjacent a cathode, even though the plate is made of a flocculent material such as mica, and therefore provides improved control of current leakage between electrodes in an electron tube. To this end, the spacer plate includes slots 26 and 28 adjacent cathode aperture 18, and in addition slots 75, 76 communicating with slots 26, 28 and aperture 18. Slots 75, 76 extend to the cathode aperture 18 and therefore traverse the region where maximum charge would build up if the slots referred to were omitted. Moreover, the intercommunication between aperture 18 and slots 25, 26, 27, 28, permits use of a continuous die surface for forming the aperture and slots referred to. This avoids the need for the high precision techniques referred to above in making the die, and reduces wear on the die.

It will be observed from the foregoing that while the slots 26, 28 are utilized in the mounting procedure shown in Figure 5, the slots 75, 76 are necessary for disposing the risers 59, 61 adjacent the path followed by a cathode sleeve during a mounting operation. If leakage slots 26, 28 were isolated from cathode aperture 18, as in the prior art, the advantageous operation permitted by jig 50 could not be used, and a charge build-up on the plate would take place to a greater degree.

The spacer plate of the invention is also of advantage in a triode type of electron tube including a wound grid 77 and a tubular anode 78 shown in Figure 8. In this structure, the anode and two spacer plates form an enclosure with which there is no visual communication. Where wound grids are used, the turns of the grid sometimes become deformed during a mounting operation. If cages having deformed grids are included in electron tubes, the tubes may be unsuited for their intended use. Therefore, it is desirable to visually inspect the grid before the assembly of a tube is processed to completion. The spacer plate according to the invention permits such visual inspection of the grid to assure that its turns are not deformed. Thus, the slots 25, 27 in the plate extend laterally of the assembled structure shown in Figure 8, so that they reach across the longitudinal array of turns of grid 77. This makes a visual inspection possible to ascertain whether any of the grid turns are deformed. Any deformation will be indicated by a displacement of a grid turn from the line registry assumed by undeformed grid turns.

While the foregoing description has concerned spacer plate 16, it will be understood that spacer plate 17 shown in Figure 2 may be of similar construction. Thus, the mounting procedures shown in Figures 4 and 5 may be employed for first mounting the electrodes on one plate, and then mounting them on the second plate.

It will be noted that the segments 21, 22, 23, 24 shown in Figure 3, are formed so that each segment has one set of opposite and parallel edges. This results in a segment having increased flexibility. While Patent 1,967,208 to Krahl shows a spacer plate having a cathode aperture defined by two segments, the edges of the segments extend in angular directions thus reducing the flexibility of the segments. Krahl shows only two segments for engaging his cathode sleeve while the spacer plate of the present invention has four segments for supporting a cathode. Therefore, a greater burden of support is assigned to each of the segments of Krahl thus making mandatory an increased rigidness of the segments. This degree of rigidness is not necessary in the case of the segments of the spacer plate of the invention, because the support of the cathode sleeve is distributed among four segments.

It will be apparent, therefore, that a novel electrode cage is provided including a novel and advantageous insulating spacer plate, and that the spacer plate referred to permits an improved method to be featured in assembling the components of the cage.

We claim:

1. An insulating spacer plate for supporting electrodes in an electrode mount assembly, said plate having an aperture therein and a plurality of slots communicating with and extending from said aperture and providing a plurality of flexible tongues, the free ends of which ter' minate at said aperture for engaging an electrode, the ends of two of said slots remote from said aperture terminating in slots transverse to said two of said slots.

' 2. An electron discharge device having a mount including a tubular cathode, and a pair of insulating spacer plates betweentwhich said cathode is mounted and supported, each of said spacer plates having an aperture therein and a plurality of slots communicating with and extending from said aperture and providing a plurality of flexible tongues the free ends of which terminate at said aperture and engage the ends of said cathode, the ends of two of said slots remote from said aperture terminating in slots transverse to said two of said slots.

3. An insulating spacer plate having four tongues integral therewith, sides of said tongues defining two parallel slots and two slot portions parallel to said slots, said two slots being coextensive, said two slot portions being aligned and extending an equal distance beyond the opposite ends of said coextensive slots, said tongues having free ends defining a round aperture through said plate, adjacent ends of said coextensive slots and remote ends of said aligned slot portions being disposed on straight lines normal to radii extending from said aperture in the plane of said plate, whereby said tongues are adapted to be flexed in a twisting motion at portions of said plate along said straight lines and at portions intermediate the ends of said tongues for facilitating receipt of an electrode in said aperture.

4. An insulating spacer plate for an electron tube, said plate having an aperture therein and four tongues integral with said plate extending from said aperture, said tongues having one group of parallel sides extending substantially radially from said aperture in the plane of said plate and defining two slot portions in aligned disposition across said aperture and extending an equal distance therefrom, said tongues having another group of sides parallel to said one group of parallel sides and spaced therefrom on both sides of said aligned disposition thereof, and partly defining two additional slots parallel to said firstnamed two slot portions, said additional two slots being coextensive and shorter than said aligned disposition of said first-named two slot portions, a straight line perpendicular to said aligned disposition bisectirig said disposition and said two additional slots, whereby said tongues are adapted to respond in a twisting flexure to a forced extension of an electrode through said aperture for facilitating said extension.

5. A spacer plate for spacing electrodes in an electron tube, said plate having two spaced apertures for receiving end portions of two cooperating electrodes, said plate including two integral segments defining a portion of one of said apertures, said segments also defining a T-shaped slot between said apertures, said T-shaped slot having a transverse portion extending perpendicular to a plane including the axes of said apertures, whereby said slot is adapted to reduce current leakage between said cooperating electrodes.

6. An insulating spacer plate having four tongues integral therewith each of said tongues having opposite rectilinear edges, said edges of all of said tongues being parallel, said tongues defining a passageway having four elongated recesses extending in said direction, two of said recesses communicating with said passageway intermediate their ends, the two others of said recesses being aligned and communicating with said passageway at their adjacent ends, whereby said recesses are adapted to impede flow of leakage current between an electrode received in said passageway and another electrode spaced from the first named electrode in a direction perpendicular to said same direction.

7. An insulating spacer plate having four tongues integral therewith said tongues extending in parallel relation to each other, said tongues having a plurality of adjacent edges at their free ends, said edges being curved to define a circular passageway, said tongues being defleetable along lines substantially perpendicular to four radii of said circular passageway angularly spaced from each other and from said same direction, Whereb'y extension of a snugly fitting electrode into said passageway is facilitated by a twisting flexure of said tongues.

References Cited in the file of this patent UNITED STATES PATENTS 1,967,208 Krahl s July 17, 1934 10 8 Smith Oct. 19, 1937 R'on'ci Mar. 2 2, 1938 Schafer Aug. 5, 1947 Brunner et a1. Jan. 2, 1951 Zo'r'gman Nov. 4, 1952 FOREIGN PATENTS Switzerland Feb. 16, 1950

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