US2409165A - Electron discharge device - Google Patents

Description

Ode 1946- H. c. THQMPSON 2,409,165

ELECTRON DISCHARGE DEVICE Filed Jan. 25, 1945 2 Sheets-Sheet l "III/Ill arrow/5y H. c. THOMPSON 2,409,165

ELECTRON DISCHARGE DEVICE Filed Jan. 25, 1945 2 Sheets-Sheet 2 IN V EN TOR. #91947 A 7i/0/77F50/7 BY Patented Oct. 8, 1946 ELECTRON DISCHARGE DEVICE Harry C. Thompson, Princeton, N. J assignor to Radio Corporation of America, a corporation of Delaware Application January 25, 1945, Serial No. 574,472

9 Claims.

The invention covered herein may be manufactured and used by or for the Government of the United States for any governmental purpose Without payment to me or assigns of any royalty thereon.

My invention relates to electron discharge devices, more particularly to such devices suitable for use at ultra high frequencies and utilizing a beam of electrons which is periodically deflected for varying the output current of the device.

Electron discharge devices to which the present invention is directed are used as mixers and amplifiers, particularly at high frequencies Where the advantages of low input conductance and ca pacity are important,

One form of beam deflection tube includes a cathode and associated elements for providing a directed beam of electron of rectangular cross section, which beam is directed toward a collector through a beam focusing and beam deflection system, the electron beam being deflected across an apertured element to determine the amount of current to the collector. The aperture may be bisected by a rod-like element, thus producing in eiiect a double aperture. Positioned between the collector and apertured element may be a suppressor which may be aligned with the aperture in the apertured element.

In the copending application of Charles W. Mueller, Serial No. 561,339, filed November 1, 1944, and assigned to the same assignee as the present application, there is shown and described a beam deflection tube of the general type de scribed above. This tube utilizes a flat plate type of construction for insuring accurate alignment of the various electrodes. In this arrangement a cathode provides a rectangular shaped beam of electrons directed toward a collector. The beam focusing and deflecting electrode system comprises a pair of oppositely disposed plates, each having a pair of rod-like elements welded to the inside surface and extending transversely of the beam path. They are oppositely disposed from each other to provide a pair of successively positioned apertures. To maintain these plates in spaced relationship and to define the rectangular apertures, separating members extending parallel to th beam path and providing supporting arms are positioned at the top and bottom of the plates. Each comprises three superimposed spacer elements, the middle one of which is shorter than the other two to provide a slot at a the end of the spacer element adjacent the collector. These longitudinally extending arms also support oppositely disposed deflecting electrodes 2 between which the beam is directed and by which the beam is deflected.

In the aperture assembly there are four elements which must be made with a high degree of precision to provide a successful device of the kind under consideration, particularly with reference to the maintenance of the dimensions and alignment effecting these four elements. The four elements of the apertured assembly include two beam forming apertures, an electron lens, a base for mounting the deflection plates and a slot for locating the intercepting wires. .tary structure for determining the relationship between the above four elements is required. In practice it was found, however, that the aperture openings varied and that the pressure to which the elements were subjected caused variations which could not be tolerated and careful inspection and adjustment were necessary to bring about the required accuracy.

It is. therefore, an object of my invention to provide an electron discharge device of the type described in which greater accuracy of aperture width and of aperture alignment with cooperating members can be had by inexpensive and practical means.

A more specific object of my invention is to make a device of the kind described in which the aperture openings are made dependent upon and equal to just one readily controllable dimension of the structure.

A further object of my invention is to provide such a device in which the aperture openings can be located automatically and symmetrically about the mid-plane of the structure. I

A further object of my invention is to provide a structure of the kind described which eliminates the need for difiusion welding.

A further object of my invention is to provide a device in which the number of parts is minimized and in which the processing can be made more routine.

A further object of my invention is to provide such a device in which a short radius of curvature of the aperture edges can be obtained,-thus improving aperture action.

A still further object of my invention is to provide a device of the kind described in which changes of aperture openings can be made by one change in one element of the assembly.

A further object of my invention is to provide such a device in which first and second apertures may be made of varying widths, and which can be less than the spacer thickness separating the apertured plates.

A solid uni- A still further object of my invention is to provide such a device in whic the aperture openings have the same mid-plane the spacer and the whole assembly, whereby the slot for the intercepting wire and the deflecting plates subsequently located and positioned by the assembly legs are located symmetrically with respect to said mid-plane.

The novel features which I believe to be characteristic of my invention are set forth with particularity in the appended claims, but the invention itself will best be understood by reference to the following description taken in connection with the accompanying drawings in which Figure 1 is a side elevation with parts broken away to show i details of construction of an electron discharge device made according to my invention, Figure 2 is a transverse section taken along the line 22 of Figure 1 and showing a top view of the electrode assembly, Figure 3 is atransverse section taken along the line 23 of Figure 1, Figure 4 is an exploded perspective of the mount assembly of the tube shown in Figures 1 to 3, inclusive. Figures 5 and 6 show details of construction of the aperture plate, Figure 7 shows details or" construction of the deflecting electrode assembly, Figures 8 and 9 show details of the spacer strip and Figures 10, 11 and 12 show partial sections of modifications of the aperture plate assembly.

Briefly, the device made according to my inven- 1 tion is housed within a non-magnetic metallic envelope provided with leads so that the device may be plugged into a proper socket or circuit. It includes a cathode assembly at one end of the envelope for providing a directed beam of electrons and a collector at the other end of the envelope for receiving the electrons with a beam focusing and deflecting electrode assembly positioned between the cathode assembly and collector.

As shown in Figures 1 to 3, inclusive, the metal envelope ill of oval shape is provided with a metallic header ll through which the various leads and supports for the electrodes extend, these leads being insulatingly sealed through the header member. The envelope and header may be made of non-magnetic material such as stainless steel. Mounted within the envelope is a cathode electrode assembly comprising the indirectly heated cathode 12 provided with heater-cathode leads l3 and i l. The cathode is surrounded by means of the shielding member l5 having a front cover member I6 provided with elongated aperture 16' through which the electrons from the cathode l2 are directed. This electrode assembly is mounted between a pair of insulating spacer members I! and i3 and clamped to the same by means of the strap l5 and positioned between the micas by means of the ears such as 29-2ii'. Mounted at the other end of the envelope is a collector 2! in the form of a 1001 supported by means of the support and lead 22. F

Positioned between the cathode and the collector is the aperture, lens and beam deflecting electrode assembly. The aperture, lens and beam deflecting electrode assembly is formed as a unit and includes the aperture portion, designated generally at and which will be described in greater detail below, provided with horizontally extending arms 26 and 2'! which support the deflecting electrodes 23-29 and the intercepting wire 30 anchored at its lower end and maintained in tension by means of the spring anchor SI permitting expansion and contraction of the wire but always assuring alignment. The wire is guided by the slot at the ends of the arms 21 and 26 as shown. Mounted at the end of the assembly is a pair of shields 32 and 33 which are supported by the header and are secured to the arms 25 and 21. These shields in turn support the apertured suppressor electrode 34 having the aperture 34 by means of the glass bead assemblies such as 35 and 35'. A lead 35" is provided for the suppressor. The end of the aperture and deflecting electrode assembly adjacent the cathode I2 is provided with a pair of transverse shield members 48 and ll. These shield members provide a linear accelerating field for the electron beam and prevent stray electrons from striking the defiecting plates.

Electrons from cathode 12 pass through the aperture l5 through the aperture assembly 25 between the deflecting electrodes 28 and 2d and are deflected across the intercepting wire 30 passing through the aperture 34' to the collector 2| The cathode end of the assembly is supported by the bracket 38.

A getter wire or trough 31 is mounted at the top of the envelope at the ends of the conductors and leads 38 and 39. A shield 38 is provided between the getter and the top of the electrode assembly.

The header is provided with a glass press 42 through which the leads ,3 and 44 extend, these being in turn connected to deflecting electrodes 29 and 28 by means of clips. The leads 43 and M extend parallel to each other through the press so that a coaxial line or Lecher wire system may be conveniently connected to the same externally of the envelope.

The details of the aperture, lens and deflecting electrode assembly are shown in Figures 4 to 6, inclusive. The aperture assembly comprises a pair of oppositely disposed U-shaped elements 50 and Si having on their inner surfaces spring aperture elements to be described having ribs extending transversely of the beam path and toward each other to form apertures. These U-shaped elements are spaced by means of spacer elements 53 and 54 at the top and bottom of the assembly and will be described more in detail below.

Supported on the arms 25 and El are the deflecting electrode assemblies 28 and 29 including a mica element such as 55, reference being had to Figure 7, including tabs or ear-like extensions such as 45 and l? at its ends. A spacer element is mounted in contacting relationship with the mica and a thin foil 49, preferably gold, wrapped around these elements to provide the deflecting electrode. The wrapped foil produces a smooth lens edge eliminating any burrs. These deflecting electrodes are assembled on the arms 26 and 2! so that the tabs or lugs, such as 46 and 4'5 register with the arms and are secured thereto by straps such as 28 fastened by welding, for example, to the arm. The aperture plate assembly and deflecting electrodes provide an electron lens as described in a co-pending application of George Ross Kilgore, Serial No. $12,625 filed June 27, 1940 and assigned to the same assignee as the present application. This construction eliminates any surfaces between the deflecting electrodes and the intercepting wire and on which any surface charges could exist.

Because all parts are held against flat surfaces tilting of electrodes is avoided. The aperture plate assembly is simple to make and the lens and 6. In accordance with my invention, I provide a pair of elongated U-shaped elements 50 and 5 I, each of which is provided with a recess or offset portion, such as 55 and 55'. Spot welded to the inside surfaces of these portions are the spring aperture elements 56 and 51 provided with spring ribs 58 and 59, 6!! and (ii. The U-shaped members and 5| are separated by means of separator elements 53-54 which are provided with lugs, such as 5G and 53, which extend down between and separate the spring members 56 and 51, the rib portions 58 and 59, 50 and 6! contacting the opposite surfaces of the lug, thus determining the width of the opening of the aperture formed by the ribs. The inserts are so dimensioned that the ribs are held against the spacer lugs and spring tensioned. In practice these apertures may be .004 inch and the die-formed spring members may be formed from rectangular blanks of sheet Nichrome .002 inch thick. As shown in greater detail in Figure the portion between the ribs is formed flat and parallel to the ribs to permit proper seating in the recess portion 55, for example, of the U-shaped elements. The ribs of the insert are thus supported on portions offset from the web and these portions constitute flexible members or springs carrying the ribs.

The aperture openings as above described are, therefore, substantially equal to the lug thickness and are independent of variations of two or three thousandths of an inch in the dimensions of other parts. Thus the correctness of the aperture opening within a few ten-thousandths of an inch depends upon one easily controlled dimension, namely the lug thickness, while the dimensions of the other parts may be held only to the ordinary tolerances of tube manufacture.

By the arrangement shown in Figure 10, for example, the spacer member 65 may have two recessed portions permitting the width of the apertures to be less than the width of the spacer and also to have different widths. For this purpose the spacer may be provided with coined depressions in its lug with which inserts cooperate.

In Figures 8 and 9 are shown the method employed for manufacturing a coined spacer. A continuous strip of thin metal 65, shown flatwise in Figure 8 and edgewise in Figure 9, has narrow depressions 66 and B7 stamped or coined across it at predetermined intervals so that, when the strip is cut along the dotted lines, spacers, each with two embossed depressions in its lug, are formed therefrom. The order of procedure is important. The coining of the depression is done after the strip is cut to width whereby the cutting burrs at the inner edge of the lug are coined down so as not to interfere with the seating of the insert ribs against the bottoms of the coined depressions.

In Figures 11 and 12 are shown alternate forms of rib-bearing spring inserts in relation to sections of the U-part webs appropriate thereto. In Figure 11 for example the spring elements 5'? and 58 have their lugs extending through apertures provided in the U-shaped members 50 and 5| and abut the spacer 65. In Figure 12 as in Figure 11 the ribs of the aperture elements 58" and 57" merely constitute the turned up edges of the spring which abut directly on the spacer element 55'.

Thus with my improved form of device I accomplish the objects enumerated above in a simple and effective manner, reducing the parts required, the operations required and insuring greater accuracy of the various elements involved in producing a tube which functions in the desiredv manner.

While I have indicated the preferred embodiments of my invention of which I am now aware and have also indicated only one specific application for which my invention may be employed, it will be apparent that my invention is by no means limited to the exact forms illustrated or the use indicated, but that many variations may be made in the particular structure used and the purpose for which it is employed without departing from the scope of my invention as set forth in the appended claims.

What I claim as new is:

1. An electron discharge device having a cathode means for supplying electrons, and an electrode in the path of said electrons, and beam defining means positioned between said cathode means and said electrode and through which the path of the beam of electrons lies, said beam defining means including a pair of oppositely disposed conducting members spaced apart to provide a passageway therebetween, registering spring-like elements mounted on said conducting members and having ribs extending transversely of the beam path on opposite sides of the beam path, and extending toward each other to provide an aperture therebetween, and means at opposite edges of said spring-like elements for maintaining said ribs in spaced relationship for positively determining the aperture width.

2. An electron discharge device having a cathode means for supplying electrons, and an electrode in the path of said electrons, and beam defining means positioned between said cathode means and said electrode and through which the Path of the beam of electrons lies, said beam defining means including a pair of oppositely disposed conducting members spaced apart to provide a passageway therebetween, registering spring-like elements mounted on said flat surfaces and having elongated ribs extending transversely of the beam path on opposite sides of the beam path and extending toward each other to provide an aperture therebetween.

3. An electron discharge device having a cathode means for supplying a beam of electrons and an electrode in the path of said electrons, and a beam defining and deflecting means positioned between said cathode means and said electrode and through which the path of the beam of electrons passes, said beam defining and deflecting means including a pair of oppositely disposed elongated U-shaped members, spring inserts mounted at the closed end of said U-shaped members and having ribs extending transversely of the beam path and toward each other to provide an aperture through which the beam path passes, and means carried by said U-shaped members and extending between said spring inserts for maintaining aid ribs in spaced relationship for determining the width of the aperture between said ribs.

4. An electron discharge device having a cathode means for supplying a beam of electrons and an electrode in the path of said electrons, and a beam defining and deflecting means positioned between said cathode means and said electrode and through which the path of the beam of electrons lies, said beam defining and deflecting means including a pair of oppositely disposed elongated U-shaped members, the legs of which lie parallel to the beam path, spring inserts mounted at the closed end of said U-shaped members, each having a pair of ribs extending transversely of the beam path, the ribs of each pair registering with the opposite pair of ribs and providing a pair of apertures successively positioned along the beam path.

5. An electron discharge device having a cathode means for supplying a beam of electrons and an electrode in the path of said electrons, and a beam defining and deflecting means positioned between said cathode means and said electrode and through which the path of the beam of electrons passes, said beam defining and deflecting means including a pair of oppositely disposed elongated U-shaped members, the legs of which lie parallel to the beam path, spring inserts mounted at the closed end of said U-shaped members and having ribs extending transversely of the beam path and in registry with each other to provide an aperture, and spacing means carried by said U-shaped members, said spacing means including spacer elements between the legs of said U-shaped members for maintaining said U-shaped members in spaced relationship and each having a lug interposed between the ribs of said spring inserts and in contact with the ribs for maintaining a predetermined spacing bctween said ribs for determining the width of the aperture between said ribs.

5. An electron. discharge device having a cathode means for supplying a beam of electrons and an electrode in the path of said electrons, and a beam defining and deflecting means positioned between said cathode means and said electrode and through which the path of the beam of electrons passes, said beam defining and deflecting means including a pair of oppositely disposed elongated U-shaped members having legs extending parallel to the beam path, spring inserts mounted at the closed end or said U-shaped members and having registering ribs extending transversely of the beam path and providing an aperture, spacing means carried by said U- shaped members including spacer elements between said legs for maintaining said U-shaped members in spaced relationship and having a lug interposed between the ribs of said spring inserts and in contact with the ribs for maintaining a predetermined spacing between said ribs for determining the width of the aperture between said ribs, said spacing elements being shorter than the legs of said U-shaped members whereby a slot is provided at the ends of the legs of said U-shaped members and a rod-like element received within said slot.

7. An electron discharge device having cathode means for supplying a beam of electrons and an electrode toward which said beam of electrons is directed, a beam focusing and deflecting electrode assembly positioned between said cathode means and said electrode and through which the beam path extends and including a pair of elongated U-shaped elements, the closed ends of which are positioned adjacent the cathode and the ends of the legs of which are positioned adjacent the electrode, said U-shaped members having offset portions providing recesses in the closed end thereof and spring-like inserts mounted within said recesses, each or said inserts having a pair of ribs extending transversely of the beam path and toward the opposite pair and providing a pair of successively positioned apertures, and spacer members clamped between oppositely disposed legs or said U-shaped member for spacing said U -shaped members and each provided with a lug extending between and in contact with said opitely disposed pairs of ribs of said spring-like sarts for determining the aperture width been said ribs. said spacer members being shorter than the legs of said U-shaped members and providing slots, and a rod-like element positioned within said slots, and deflecting electrodes mounted between each pair of legs of each U- shaped member and on opposite sides f the beam path for deflecting the electron beam.

8. An electron discharge device having cathode means for supplying a beam of electrons, and an electrode in the path of said electrons, and a beam deflecting electrode assembly positioned between said cathode means and said electrode and through which the beam path lies and including a pair of oppositely disposed members, spring-like inserts supported on said members, each having a pair of ribs extending transversely of the beam path, the ribs on one insert extending toward the ribs on the other and providing a pair of successively positioned apertures and spacers positioned between said oppositely disposed members and having portions of difierent thicknesses positioned between each pair of oppositely disposed ribs at the ends thereof, whereby the aperture Widths differ from each other.

An electron discharge device having cathode means for supplying a beam of electrons, and an electrode in the path of said electrons, and a beam d iecting electrode assembly positioned between said cathode means and said electrode and through which the beam path lies and including a pair of oppositely disposed conducting members having fiat surfaces, spring-like inserts supported on said fiat surfaces, each having a pair of ribs extending transversely of the beam path, the ribs on one insert extending toward the ribs on the other and providing a pair of successively positioned apertures and a spacer positioned between said conducting members and having portions of different thicknesses positioned between each pair of oppositely disposed ribs at the ends thereof, whereby the aperture widths difier from each other,

HARRY C. THOMPSON.

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