US2401740A - Electron discharge device - Google Patents

Description

June il, 1946. AG. R. KLGORE 2,4m@

ELECTRON DISCHARGE DEVICE original Filed May 28, 1941 y irme/ffy Patented June 11, 1946 NETE STES

ATENE 2,401,740 ELECTRON DISCHARGE DEVICE George Ross Kilgore, Princeton, N. J., assignor to Radio Corporation of America, a corporation of Delaware (Cl. Z50- 27) 4`1Claims. -1

My invention relates to electron discharge devices, more particularly to such devicessuitable for useat high frequencies and employing a beam of electronsland Vdeflecting means for said beam to produce a. modulated output current.

The present application is a division of my copending application, Serial No. 395,621 led May 28, 1941,--Patent No.` 2,372,282, dated March 27, 1945, and.- assigned to the same assignee as the present application.

Inconventional devices'employing a beam and utilizing deflection means, the electron stream is modulated by deflecting the beam past an aperturegin. an apertured electrode. Such a device is ineilicientinsofar as the intercepted current which becomes waste currentY isV concerned, and requires the use -of anadditional electrode, that is the apertured electrode. trode capacity to the tube, which at the higher frequencies is undesirable since this further affects the eciency of the tube-as well as increases the number of leakage pathsbetween the various electrode leads.

Hence, it is an object of my invention to provide an electron discharge device particularly useful at high frequencies and employing a beam and delecting means for the beam for producing a modulated output current.

More specifically, it is an object of my invention to provide such an electron discharge device in which the transit time of the electrons, the shape and position of the electrodes and the frequency of the controlling voltage or voltages are suchy that the action of the deection means produces a modulated current in the output of the electron discharge device.

-The novel features which I believe to be characteristic of my invention are set forth with-particularityv in the appended claims, but the invention itself will'best beunderstood by reference to the following vdescription taken in connection With-the accompanying drawing in which Figure 1 isla diagramv explaining the theory of operation of tan electron discharge device made according to my invention, Figure 2 represents the output current of a device made-according to my invention,'Figure-3 is adiagrammatic longitudinal section-of an electron discharge device and circuit made according to my invention, Figure 4 is a modification of the device shown in Figure 3 and its associated circuit, and Figure`5 shows a tube corresponding to the tube in Figure 4 but used lin the push-pull output circuit arrangement.

Referring to the drawing inFigure l, the point Q represents an electron source for providing a 'Ihis electrode adds elecbeam of electrons directed between a pair of deflecting electrodes 'D1 and D2. These electrons are directed toward an anode or output electrode P having positioned in front of it a screen lS. As the beam is deflected, the path length of the electrons from Q to plate P is varied and the transit time of the electrons will vary accordingly. If B1 and B2 represent the maximum excursion of the beam and the difference in transit time along the paths QB1 and QBz is made to equal one-half the period of the .appliedv alternating control voltage on plates D1, D2, then on the upward swing of the beam, an electron will reach-B1 at the same instant an electron which left the source of electrons Qone-half cycle earlier reaches B2. Thus, it is possible by the application of proper biasing voltages and proper controlling voltage to have all the electrons which pass through the same plane T T on the upward swing reach the output electrode P at approximately the same instant of time.

On the downward deflection, however, the `electrons will reach the plate P at wider andwider intervals. As a result the electron current reach-r ing the output electrode P will have a wave shape something like that shown in Figure 2. Thus, with a uniform fiow of electrons from the'source Q a modulated current is produced inthe Qutput electrode P. The screen S is introduced close to the plate P so that the high' frequency curey rent induced in the output electrode l? will not be reduced appreciably by transit time effects.

The incorporation of an electrode structure corresponding to that shown in Figure l in an electron discharge device, and its associated circuit, is shown in Figure 3. An indirectly heated cathode Il providesa source of electrons which is formed into a beam by means of the longitudinal cylindrical electrode system having the apertured inserts I3 and Ill, the apertures being aligned to provide beam formation. The beam is directed between a pair of deflecting electrodes i5 and Iii toward output electrode Il inclined with respect to the beam, a screen electrode being provided in front of the output electrode. The cylindrical electrode system I2 may surround the output electrode and screen to completely screen it from output interference, if so desired. Input circuit 2D is connected between the deflecting electrodes l5 and I6 and a positive point on the voltage source 22, the output 2l being connected between the voltage source. 22 and the output electrode Il, by-passing of the high frequency current of the screen being accomplished by means of high frequency .condenser 23 whichlalso the electron transit time difference between the maximum points of swing equal to one-half the period of the frequency of the applied voltage Y to the deilecting electrodes I and I6, in this way obtaining an output such as shown in Figure 2.

In the modification shown in Figure 4 a special case is shown in which a pair of output electrodes are displaced a distance equal to a multiple oiV one-half period of. the transit time of an electron during half a period. Here again cathode 26 supplies electrons which are formed into a beam by an electrode system which cornprises cylinder 21 and apertured electrodes 28 and 29.7` The beam of Velectrons passes between deilecting electrodes` 3U-3I to output electrode elements 32 and 34 screened by means of screen electrodes 33 and 35. Electrode 33 may be on both sides of electrode element 32 to completely shield it from the electron stream when it passes to electrode 34. The input voltage is applied by means of input circuit 36 to the deflecting electrodes Sii- 3L andoutput circuit 31 is connected to the electrode 34 electrically connected to electrode 32 by means of conductor 39. The spacing between electrodes 32 and 34 is such that the'transit time "of electrons between the two electrodes 32 and 34 is a multiple of onehalf period of the applied controlling voltage. In 4the case shown the transitctime -r is made equal to one period T. 'I'hus the current pulses reach 32 and V:ill in phase. The result of this is a current having-twice the amplitude ilowing for a half ,period of the applied input voltage.

In Figure 5 the output electrodes 32 and 34 are connected to opposite sides of apush-pull output transformer.- Inasmuch as the transit time space betweenV the two electrodes is made equal toene-half period, the current flowing to each output electrode is in the proper phase relationship to bring about excitationv of the output transformer 31'.

While'I have indicated the preferred embodimentsof Vmy 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 byfnoV means limited to the exact forms illustrated or the use indicated, but that many variations maybe 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:

l. YAnY electron discharge vdevice having cathode for supplying electrons and means for formingV electrons from said cathode into a directed beam, an output electrode for receiving said electrons anda pair of deilecting'electrodes between which said beam is directed to said output electrode, said output electrode including a member having a plane surface positioned at an angle to the path of said beam. said beam formingvmeans comprising a tubular member surroundingsaid defiecting electrodes and said output electrode and having a transverse element closing one end of said tubular member adjacent said cathode and provided with an aperture registeringwith said cathode and the other end of said tubular member being closed by a transtrodes is of the order of 'one-half verse element, whereby said deilecting electrodes and output electrode are completely shielded, an input circuit connected to said deilecting electrodes for applying an alternating controlling voltage to said deflecting electrodes, an 4output circuit connected to said output electrode, a

Vsource of voltage, means connected between said source of Yvoltage and said electron discharge vdev ice for `providing biasing voltages, the frequency of said controlling voltage being such that the difference in transit time between the output electrode surface nearest said deflecting electrodes andthe part of said output electrode most distant from said deilecting electrodes is of the order of one-half period of oscillation of the controlling voltage.

2. An electron discharge device having a cathode for supplying electrons and means for forming the electrons from said cathode into a directed beam, an output electrode for receiving said electrons and a pair of deflecting electrodes between which said beam is directed to said output electrode, said output electrode including a member having a plane surface positioned at an angle to the path of said beam, and a screen electrode adjacent said output electrode, said beam forming means comprising a tubular member surrounding said deecting electrodes, said output electrode and said screen electrode and having a pair of spaced transverse elements closingvone end of said tubular member adjacent said cathode and provided with apertures registering with said cathode,-and a transverse element closing the other end oi' said tubular member, whereby said deflecting electrodes, output electrode and screen electrode are completely shielded, an input circuit connected to said deflecting electrodes for applying an'alternating controlling voltage to said defiecting electrodes, an output circuit connected to said output electrode, a source of voltage, means connected between said source of voltage and said electron discharge -device for providing biasing voltages, the frequency of said controlling voltage being such that the diil'erence in transit time between the output electrode surface nearest said deilecting electrodes and thepart of said output electrode most distant from said detlecting relecperiod of oscillation of the controlling voltage.

3. An electron discharge device having a cathode for supplying electrons Vand means for forming the electrons from said cathode into a directed beam, an output electrode'for receiving said electrons and a pair of deflecting electrodes between which said beam is directed to said output electrode, said output electrode including a member having a plane surface positioned at an angle to the pathrof said beam, and a screen electrode adjacent said Voutput electrode, said Vbeam formingmeans comprising a tubular member surrounding said deilecting electrodes, said output electrode and said screen `electrode and having a pair of spaced transverse Y said electrons and a pair of deiiecting electrodes between which` said beam is directed to said output electrode, said output electrode including a member having a plane surface positioned at an angle to the path of said beam, and a screen electrode adjacent said output electrode, said beam forming means comprising a tubular member surrounding said deiiecting electrodes, said output electrode and said screen electrode and having a transverse element closing one end of said tubular member adjacent said cathode and provided with an aperture registering with said cathode, and a transverse element closing the other end of said tubular member wh'ereby said deecting electrodes, output electrode and screen electrode are completely shielded.

GEORGE ROSS KILGORE.

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