US2205500A - Electron discharge device - Google Patents

Description

June 1940. M. J. o. STRUTT :1- AL 2,205,500

ELECTRON DI SCHARGE DEVICE *3 jhm -m- L24 2/ IINVENTORS MAXIMILIAAN J.O.STRUTT BY a P TRUS H.J.A.KLEYNI'-IN fl w ATTORNEY.

J1me 1940. v M. J. o. STRUTT El AL 2,205,500

ELECTRON DISCHARGE DEVICE Filad Nov. 24, 1937 3 Sheets-Sheet 2 INVENTORS MAXIMILIAAN J.O.STRUTT 8. P TRUS H.J.A.KLEYNEN W @QJQW M ATTORNEY.

June 25, 1940- M. J. o. STRUTT Er AL 2,205,500

ELECTRON DISCHARGE DEVICE Filed Nov. 24, 1937 3 Sheets-Sheet 5 INVENTORS MAXIMILIAAN J.O.$TRUTT 8' P RUS A.KLEYNE| ATTORNEY.

axis of the cathode.

Patented June 25, 1940 ELECTRON DISCHARGE DEVICE Maximiliaan J.- 0. Strutt-and Petrus H. J. A. Kleynen, Eindhoven, Netherlands, assignors, by mesne assignments, to Radio Corporation of America, New York, N. Y., a corporation of Delaware Application November 24, 1937, Serial No. 176,174

In Germany November-.26, 1936 6 Claims.

This invention'relates to a device comprising an electric discharge tube having a cathode, an anode and two or more other electrodes, one of which consists only of a few rods or slat portions,-

and in which the electrons emitted by the cathode are united into beams,'the grid-voltage anode current characteristic curve being determined by influencing the dimensions of the beam.

The principal object of the invention is to provide an electron discharge device which can be built easily and in a comparatively simple manner to have the desired characteristic curve.

In accordance with the present invention, the electrons issuing from the cathode are concentrated in radial beams by rod or plate-shaped members arranged parallel with the longitudinal axis of the cathode,'and means at the ends of the electrode system afie'ct the form of the radial beams in a direction parallel with the longitudinal In this way the spot to be cast on the anode can be given any optional form.

In one form of tube constructed according to the present invention an intercepting electrode is mounted in front of and close to the anode, and so shaped that; in combination with the beam-shape, a characteristic curve is obtained having the desired form in adefinit'e case. I

The end electrodes which extend in a plane substantially normal to the cathode, may be plateshaped or sheet electrodes and may be connected to a point of'constant' potential, for instance to the cathode or'to another'point of constant or negative potential or to a variable voltage, so that variations of the voltageaffect the electrostatic field due to the end electrodes and cause a variation in the widthof the beam in a direction parallel with the cathode and consequently in the shape of the beam. One or more additional grids maybe provided between the control grid and the intercepting electrode, one of which additional grids may act as a protective grid, although the functionsof the intercepting electrode and of the protective grid may be united in one electrode. The invention may be used with pentodes and octodes wherein an additional pentode suppressor grid is provided between the intercepting electrode and the anode. The invention will be more clearly .understood by reference to the accompanying drawings in which, by way of example, various, forms of embodiments of the invention are shown and in which Figures 1 and 2 are longitudinal sections of mounts of tubesembodying the invention, Figure 3 is the forrnof the anode spot obtained with tubes constructed as shown in'Figures 1 and 2, Figures 4 and 5 are longitudinal sections of other modifications, Figure 6 is a cross-section of Figure 1 along the section line 6- -6, Figures '7 and 8 are longitudinal sections of other modifications, Figure 9 shows-the anode spot produced bytubes constructed as shown in Figures '7 and 8, Figure 10 shows a mount partly in longitudinal section of still another modification, Figure 11 is the anode spot produced by the tube shownin Figure 10, Figure 12 is a plan view of the screen grid with which a straight characteristic curve can be obtained, Figure 13 is a plan View of a screen grid by which an exponential grid voltageplate current characteristic curve may be obtained, Figure 14 is a developed view of the anode,

of the tube shown in Figure- 10, and Figure 15 shows the anode spot produced by tubes constructed as in Figures 4 and 5. l

In Figures 1 and 2 the mount comprises a press l,which carries, an electrode system comprising a rectilinear cathode 2, preferably of the indirectly heated type, a control grid 3 consisting'of rods parallel to the longitudinal axis of the cathode and a tubular anode 4 surrounding and coaxial with the cathode and the control grid. By the effect of the control: grid voltage the electron discharge from the cathode to the anode is concentrated or united into electron beams which are flattened and are in general rectilinear in cross-section with the width of the beam extending lengthwise of the cathode. Between the beam forming control grid and the anode is mounted an apertured intercepting'electrode or anode 4a with an aperture 4bin the path of the electron beam. The form of the aperture in the inter cepting electrode in combination with the shape of the electron beam detern'iines the shape of the anode spot and the shape of the characteristic curve of the tube. The shape of the electronbeam formed by the control grid 3'is afiected and determined by end members such as the sheet electrodes or discs 5 and the rod electrodes 6 in Figures 1 and 2, which are mounted at the oppo-' site ends of the electrode system so as to extend in planes normal to the cathode. By impressing voltage on these end members 5 and 6 an electrostatic field is produced which will afiect the beam shape in a direction parallel with the longitudinal axis. of the, cathode. Tubes constructed as shown in Figures 1' and 2 will produce ananode spot. illustrated in Figure 3 and the form of this spot varies with variation in voltage of the control grid and of the end members. The

Figure 1. An input transformer 20 has connected to one side of its tuned secondary the lead to the control grid 3 and its other side connected to the anode voltage supply 2|. The end plates 5 and the end control rods 6 may be connected to the grid side of the secondary of the transformer by means of conductor 22 and adjustable tap 23 or they may be connected directly to the grid lead as indicated by the dotted line.

ply source.

plane of beams produced by control grid 3. This of the input transformer and, therefore Vary in potential with variations in control grid voltage.

When the control grid voltage is high, the anode spot, as illustrated in Figure 3, has the form or outline ll. As the control grid voltage decreases, the anode spot shrinks to the form [2, and at still lower control grid voltages, shrinks to the form l3.

Figures 4 and 5 show a modification in which the end members for affecting the shape of the electron beam in a direction parallel to the cathode are in the form of rods 1 located at opposite ends of the electrode system and by a rigid metal connector Ia to the control grid 3 and carried by it if desired, although they are shown provided with a separate support and lead.

Figure 15 shows the form of the anode spot produced by the tube shown in Figures 4 and 5, the anode spot having the form II at high grid voltages and shrinking first to the form l2 and then to the form l3 as the control grid voltage is lowered. The effect of eliminating the end plates 5 is shown in Figure 15 where wider and longer legs appear at the top and bottom of the spot shown in Figure 11. The reason for this is that the beam is compressed only by the field of the rods I in the path of the beam, whereas in the construction shown in Figures 1 and 2 both the shields 5 and the end rods 6 exert an in-, fiuence on the shape or the beam and have a greater compressive action than the rods 1 alone. The construction of the tube shown in Figures 4 and 5 is simpler than that shown in Figures 1, and 2' and in the resulting anode current the difierence between maximum and minimum cur: rent is greater. Figures 7 and 8 illustrate a modification in which the end members are sheets or discs 8 at opposite ends of the electrode system, these end members having a separate connction by which any desired voltage may be impressed'upon the end members. When the end members are cone nected to the control grid, the anode spot, as shown in Figure 9, isin general, similar to that obtained from the tubes shown in the preceding figures, the spot having the form I l at high con,- trol grid voltage, and shrinking to the forms l2 and I3 in succession as the control grid voltage is lowered.

Figure 10 is a longitudinal section ofa modi fication in which the sheet ordisc end members .8 are similar to those shown in Figure 7; the anodes Hare in the developed state of the form illustrated in-Figure 14 so as to provide two The output :is fed to the transformer 24. If desired, the end plates 5 could be connected to the cathodef'The'" intercepting electrode or anode 4a is connected to.

an intermediate point on the anodevoltage sup-.

It will be noted that the end rods 6 extend normal to the cathode and lie in a median diametrically opposite slots or apertures in the path of the electron beams from the cathode, and are surrounded by an electrode 10. When the end members 8 of the tube shown in Figure 10 are connected to the cathode, preferably by a connection 8a inside the tube, the anode spot obtained has the form shown in Figure 11. With these connections, the anode spot at high con- ..tro1 grid voltage is of the substantially square form H and as the grid voltage is lowered, the

" spot shrinksto the rectangular forms l2 and I3.

The anodes 9 couldbe replaced by cylindrical anodes having apertures shaped like the anodes shown in Figure 14. In this case the apertured electrode would serve as the intercepting electrode, the apertures of course lying in the path otthe beam from the cathode 2. It is also possible in the construction shown in Figure 10 to provide the electrode Ill with a surface which will promote secondary emission, the secondary electrons returning to the anodes 9. If desired, the electrodes 9 could be replaced by intercepting electrodes made of gauze, properly treated to promote secondary emission for increasingthe output to the electrode Ill.

The intercepting electrode between the control grid. 3 and the anode 4 may take the form of a screen grid having a specially shaped aperture for determining the shape of the characteristic curve. Figure 12 shows a screen grid with an hour glass shaped aperture [5 covered by a wire meshand by means of which in conjunction with the mount structure shown in Figure 10 a straight characteristic curve can be obtained. Figure 13 shows a screen grid in which the aperture I6 covered by a wire mesh and of the generalanode, a beam forming electrode adjacent said; cathode and consisting of spaced conductors substantially parallel with the longitudinal axis of the cathode for concentrating the electron dischargefrom the cathode into a flattened radial beam with its Width extending lengthwise of the cathode, intercepting electrode adjacent said beam. forming electrode and between said beam forming electrode and said anode, said intercept-r ing electrode having in the path; of the beam an aperturelsmaller than the normal cross-sectional areaof thebeam at said intercepting electrode, and means at the opposite ends oi-the electrode system for producing an electrostatic field to vary the width of the electron beam in a direction parallel with the longitudinal axis of the cathode. 2. A device as defined in claim 1 in which the cathode is indirectly heated and the means for producing an electrostatic field comprises end electrodes mounted at the ends of the electrode system and extending in a plane normal to the cathode 'and connected to the cathode.

3. An electron discharge device comprising an elongated cathode, a control grid comprising a pair of spaced conductors mounted parallel with and on opposite sides of said cathode to produce a sheet electron beam extending lengthwise of and radial to said cathode, end electrodes at opposite ends of said cathode extending normal tofsaidcathode and to the plane of said rods, means electrically connecting said end electrodes to said control grid, an anode surrounding said cathode and control grid, and an intercepting member between said anode and said control grid having intermediate its ends and in the path of said radial beam an aperture narrower than the normal width of said beam in a direction parallel to said cathode.

4. An electron discharge device having an electrode system comprising a rectilinear cathode, a beam forming electrode adjacent said cathode for concentrating the electron discharge from the cathode into a flattened radial beam with its width extending lengthwise of said cathode,two juxtaposed anodes of different diameters surrounding and coaxial with said cathode, the inner one of said anodes having in the path of said electron beam an aperture with its Width extending lengthwise of said cathode and less than the normal width of the beam at said inner anode, end electrodes mounted at opposite ends of the electrode system and projecting in planes substantially normal to said cathode and along the edge of said electron beam on opposite sides of the aperture in said inner anode and means for connecting said end electrodes to said beam forming electrode. j

5. An electron discharge device comprising a rectilinear cathode, an anode surrounding said cathode, a beam forming electrode adjacent said cathode for concentrating the electron discharge from said cathode to said anode into a flattened beam radial to said cathode and with its width parallel to said cathode, end electrodes at opposite ends of said electrode system extending substantially perpendicular to said cathode and said beam forming electrode and parallel to the edges of the radial electron beam, means conanode consisting of two elongated spaced conductors parallel with and on opposite sides of the cathode to form the discharge from said cathode to said anode into a sheet beam radial to said cathode and with its width parallel to said cathode, two end electrodes electrically connected to the control electrode inside the tube and mounted at the opposite ends of the electrode system to extend in planes normal to the cathode, and an intercepting electrode between said beam forming electrode and said anode having in the path of said beam an aperture narrower than said beam. I

MAXEMILIAAN J. O. STRUTT. PETRUS H. J. A.' KLEYNEN.

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