US2369750A - Electronic valve device - Google Patents

Description

Feb. 20, 1945. P. NAGY ET AL 2,369,750

ELECTRONIC VALVE DEVICE Filed June 16, 1942 3 SheetIs-Sheet l Feb-20, 1945. P. NAG'Y ETAL ELEC TRON IC VALVE DEVICE 3 Sheets-Sheet 2 m; AAA F F Filed 'June 16, 1942 Feb. 20, 1945. P. NAGY ETAL ELECTRONIC VALVE DEVICE 1942 s Sheets-Sheet 5 Filed June 16,

Patented Feb. 20,1945

OFFIQE.

ELECTRONIC VALVE DEVICE Paul Nagy, Richmond, and Marcus James Goddard, Newbury, England Application June 16, 1942, Serial No. 447,277

In Great Britain July 23, 1941 17 Claims.

The present invention relates to electronic devices such as thermionic valves of the kind wherein an electron beam is focussed on to a target electrode, and wherein a signal isobtained as a result of deflecting the electron beam across the target electrode.

Numerous devices of this type are known in the prior art. For example, in British Letters Patent No. 443,364, a device is described wherein an electron beam is focussed on to a pair of output electrodes and output signals are produced by deflecting the beam across the line of separation between the two output electrodes. The electron image formed on the output electrodes is in the form of a long, narrow strip, and the beam is deflected at right angles to the length of the image. This deflection is, however, in a direction oblique to the edge of the output electrodes acros which deflection takes place. This latter fact restricts the mutual conductance, and therefore the amplification, of the device. In the preferred forms of the present invention an elongated electron image is formed by the electron beam, which is deflected at right angles to the length of the image, but the target electrode is so-disposed that one edge, across which the beam is deflected, is substantially parallel to the length of the electron image, so that the beam i deflected at right angles to this edge. This edge will be hereinafter referred to as the active edge of the target electrode. Devices in which a beam is focussed and deflected in this manner are described in British Letters Patent Nos. 366,053, 467.573 and in the specification numbered 476,653.

When the electron beam is. deflected so that it does not fall wholly on the target electrode, that portion of the beam which does not fall on the target electrode must be collected by an additional collecting electrode. This collecting electrode has no direct electrical connection to the target electrode, and consequently during operation of the device the two electrodes do not in general have the same potential. If no arrangements are made to control the movements of secondary electrons, those secondary electrons which are emitted due to the action of the electron beam from the electrode which has instantaneously the more negative potential will-pass to the other electrode. This effect tends to neutralise the useful action of the electron beam. and thereby to reduce the amplification obtained from the device.- Furthermore, this transfer of secondary electrons from one electrode to the other may not be linearly proportional to the deflection of the electron beam, and thus cause non-linearity in the amplification of the device, whereas a deflection modulated valve, when suitable precautions are taken against disturbing influences, gives a substantially ideally linear amplification characteristic since the output potential is a direct linear function of the displacement of the electron image, which is in turn a direct linear function of the input potential. Also, at ultra-high frequencies, this transfer of secondary electrons further reduces the efficiency of the device, because the transit time of the secondary electrons collected by the target electrode is of the same order as the periodic time of the signals amplified. The magnitude and linearity of the amplification may also be de'leterio-usly affected by space charge arising in the neighbourhood of the two electrodes.

The present invention provides means whereby the secondary electron transfer and the space charge effects are controlled, thedeleterious effects thereof being thereby overcome. By this control of the secondary electron transfer, the effects of the transit time of the secondary elec trons at ultra-high frequencies can also'be eliminated. According to the present invention, control of the transfer of secondary electrons from the target electrode to other electrodes of the device and vice versa is elfected by a control electrode system arranged adjacent the target electrode, which control electrode system also serves substantially to eliminate the deleterious efiects of space charge. The control exerted by the control electrode system is such that the transfer of secondary electrons from the target electrode to other electrodes of the device or vice versa is substantially zero or substantially complete. By this means the invention provides for the elimination of the effects of the transit time of the secondary electrons at ultra-high frequencies. According to one feature of the invention the control electrode system acting in conjunction with the target electrode, produces a reaction on the electron beam which serves to enhance or to reduce the deflection thereof, thereby increasing the amplification or, alternatively, the stability of the device, I

The invention will now be more particularly described with reference to the accompanying drawings, wherein- Figure 1 shows a device according to the invention wherein, the transfer of secondary electrons from the target electrode to other electrodes of the device is substantially complete while the transfer of secondary electrons from other electrodes of the device to the target electrode is substantially zero. v

Figure 2 shows the output part of a device according to the invention wherein the transfer of secondary electrons from the target electrode to other electrodes of the device and vice versa is substantially zero.

Figure 3 shows the output part of a device according to the invention wherein the transfer of secondary electrons from the target electrode to other electrodes of the device and vice versa is substantially complete. Figure 3a shows an alternative form of the device shown in Figure 3.

Figure 4 shows an alternative form of the output part of the device shown in Figure 1.

Figure 5 shows a circuit wherein the device of. which the output portion is shown in Figure 4 is employed as an amplifier.

Figure 6 shows a circuit wherein a modified form of the device of which the output portion is shown in Figure 4 is employed as a detector.

Figure '7 shows a circuit wherein the device of which the output portion is shown in Figure 4 is employed as a frequency changer.

Figure 8 shows a circuit wherein the device of which the output portion is shown in Figure 4 is employed as an oscillator.

Referring now to Figure 1, C represents a cathode from which electrons are emitted, e. g., thermionically due to heating of the cathode. G is a grid by the potential of which the electronic current leaving the cathode is controlled. Al and A2 are respectively a first and second anode whereby the electrons leaving the cathode are concentrated into a beam of small cross-section and focussed into an electron image in the region of a target electrode 0 which constitutes an output electrode. The electron optical system shown in Figure 1 is shown by way of example only. The invention may employ any suitable system for producing an electron image in the region of the output electrode. Preferably the cathode is elongated in the direction at right angles to the plane of Figure l, and the electron image is likewise elongated, its length being parallel to the edge Z of the output electrode 0, which edge is the active edge of the output electrode, and is formed in the plane of the edge Z. Deflection plates Pl, P2 are provided, and when potential variations are applied between these plates, the electron image is caused to oscillate at right angles to the edge Z. The undeflected positionof the electron image is so adjusted that this oscillation takes place across the edge Z, so that a greater and lesser proportion of the electron beam is intercepted by the output electrode 0 during this oscillation, thus producing signals on the output electrode. That part of the beam which is not intercepted by the output electrode is collected by a collector electrode E l.

Electronic valves conforming in essential details to this description are already known. The novel feature of the present invention consists of the provision of an electrode system adjacent'the output electrode of such form that the transfer of secondary electrons from the output electrode to this electrode system and vice versa is substantially zero or, alternatively, is substantially complete. In the form of the device shown in Figure 1, an electrode E2 and a grid E3 are provided which are connected to the collector electrode El. The electrodes El, E2 and E3 are maintained at a potential more positive than that acquired by the output electrode 0 during operation of the device. Hence substantially all secondary electrons emitted by the output electrode 0 are attracted to and collected by the electrode Ill ill)

system El, E2, E3, but secondary electrons emitted by the collector electrode El and the grid E3 do not pass to the output electrode 0 because this is at a lower potential, but are retained by the system El, E2, E3. The electrostatic field produced between the electrodes El, E2, E3 and the output electrode 0 also substantiall eliminates space-charge in the region adjacent the electrodes.

If the secondary emission coefficient of the output electrode 0 is less than unity, the rate of charging increases in a negative sense when the electron image is deflected further on to the output electrode. If the secondary emission coefficient is greater than unity, therate of charging increases in a positive sense when the electron image is deflected further on to the output electrode. The latter method permits a larger output to be obtained, since the secondary emission coeflicient can be made several times greater than unity. The secondary emission coefficient can be enhanced by inclining the output electrode obliquely to the direction of incidence of the primary electrons as shown in all the figures. Such inclination of the output electrode also increases the area of the output electrode upon which the electron beam impinges, thereby reducing the current intensity of the beam per unit surface area of the output electrode. This increases the life of the secondary emissive surface and improves the heat dissipation properties of the output electrode.

If the secondary emission coefiicient of the output electrode for the angle of incidence of the primary electrons employed be denoted by S/P, then the factor 1,0, defined as the numerical value of (S/P-l), may be called the multiplication factor due to secondary emission. The mutual conductance p of. the valve can be expressed in terms of the factor 1 the total beam current L in the electron beam, the cross-sectional width 2a of the electron beam in the direction at right angles to the active edge Z of the output electrode in the plane of the edge Z, and the deflection sensitivity Ds, i. e., the deflection of the electron beam across the edge Z per unit change of potential of the input signal applied to the deflection plates Pl and P2, by the relationship:

It is well known that the amplification of a valve increases if the mutual conductance is increased. The above formula. thus shows not only the advantage of making the multiplication factor il large, but also that of making the width 2a. of the beam at right angles to the active edge Z of the output electrode small, as mentioned hereinbefore. According to one feature of the present invention, a volume control is provided by focus-- sing and defocussing the electron beam thereby changing the value of 2a. This defocussing may be carried out in the orthodox method by changing the potential of the first anode Al. This however, may increase the cross-section of the beam between the deflection plates, which is undesirable if these are very close together to give high deflection sensitivity. An alternative method of defocussing consists of applying a diiferent potential to the plates Pl and P2. Preferably these plates should be made each more negative by the same amount, thereby compressing the beam in the region of the plates. A third method of defocussing employs an additional electrode Ell (Figure 1). Normally the electrode El land electrode E3 should be at second anode potential. Defocussing can be produced by changing the potential of the electrode El l. Defocussing may also be produced by a combination of any or all of the three methods suggested, or by any other suitable means.

According to one feature of the present invention the potential changes of the output electrode produce a reaction on the electron beam. It will be seen that, in the form of the device shown in Figure l, the electron beam passes between the output electrode and the electrode E2 which is at a substantially constant potential. The difference of potential between 0 and E2 deflects the electron beam. If the beam is moved under the influence of an input signal so that it moves further on to the output electrode, then, if the secondary emission coefiicient of the output electrode is greater than unity, the output electrode becomes more positive. This change tends to pull the electron beam still further on to the output electrode, so that the reaction between the output electrode and the electrod E2 is regenerative. If, however, the secondary emission coeflicient of the output electrode is less than unity, then when the electron beam moves further on to the output electrode, the output electrode becomes more negative, and this tends to push the electron beam back to its original position. The reaction between the output electrode and the grid E2 is therefore degenerative. If the output electrode is connected through an output resistance R to a point maintained at a constant potential, if A is the reaction deflection sensitivity of the output electrode system, i. e., the movement produced in the beam due to this reaction per unit change of potential of the output electrode, and if further a positive sign be ascribed to A if the reaction is regenerative and a negative sign if the reaction degenerative, then the amplification A of the valve is given by:

It is here assumed that the internal impedance of the deflection modulated valve approximates to infinity due to the ideal screening between input and output electrode systems. Thus the amplification of the valve when there is no reaction of any kind is equal to R, which is the limit when the internal impedance R: becomes infinite of the general formula for amplification, viz:

RL m The amplification formula taking into account the reaction efiect of the electrodes 0 and E2 is only strictly true when the load R is ohmic. A similar but more complicated condition obtains when the load is a complex impedance.

Theoretically the amplification can be increased indefinitely by suitably choosing the values of R, and A. If, however, this process is carried too far. the valve becomes unstable, and if RA becomes equal to or greater than Ds, the valve goes into oscillation. For some purposes stability may be more important than high amplification. In such cases the reaction between the output electrode and the electrode E2 may be made degenerative, or more advantageously it may be reduced to a minimum by inclining the output electrode in the opposite direction as shown in Figure 4. The electron beam in this form of the device does not pass between the active or secondary electron emit- 1 more an additional electrode E9 may be provided which substantially counteracts the reactive effect of the electrode E2.

An alternative form of the output members of the device is shown in Figure 2. This form is similar to the form shown in Figure 1, but additional grids E4 and E5, connected by an electrode E6, are provided. If the system E4, E5, E6 is maintained at a potential more negative than either the output electrode 0 or the electrode system El, E2, E3, then secondary electrons are substantially completely prevented from leaving the output electrode 0, and secondary electrons from the electrode El and the grid E3 are prevented from passing to the output electrode O, by the'electrostatic fields produced be tween the output electrode 0 or the electrode system El, E2, E3 and the system E4, E5, E6.

Deflection of the electron beam further on tov the output electrode causes the output electrode to be charged more negatively, and the reaction between the output electrode 0 and the electrode E6 is degenerative. If, however, the electrode system E4, E5, E6, is connected to the collector electrode El, then the device operates in the same way as the form of the device shown in Figure 1, and if the secondary emission coefficient of the output electrode is greater than unity, the reaction between the output electrode The- O and the electrode E6 is regenerative. form of the device shown in Figure 2 therefore provides a method by which the reaction may be made regenerative or degenerative merely by appropriately connecting the electrode system E4, E5, E6.

Figure 3 shows another alternative form of the device. The collector electrode El is connected to an additional electrode E8 and a grid E7, and is maintained at a more negative potential than the target or output electrode 0. The electrode E3 is maintained at a more positive potential than the output electrode 0. Both the output electrode 0 and the collector electrode El have a secondary emission factor greater than unity, and either or both may be inclined to the direction of incidence of the primary electrons to enhance the secondary emission coefficient. The secondary electrons emitted by the output electrode 0 are substantially all collected by the more positive electrode E3, the output electrode consequently becoming charged in a positive sense. The secondary electrons emitted by the collector electrode El are prevented from reaching the electrode E3 by the electrode El, and consequently go to the output electrode 0 which is more positive than El, thereby charging the output electrode in a negative sense. Consequently, when the electron image oscillates across the active edge Z of the output electrode, the output electrode is charged alternately in a more positive and in a more negative sense. The action of this form of the device is essentially push-pull, in contradistinction to that of the forms previously suggested which is essentially all push or all pull. In fact, if S'/P' is the secondary emission coeificient of the collector electrode El, the multiplication factor due to' secondary emission from this electrode is ='S'/P, and the mutual conductance of the valve according to this construction is:

The mutual conductance is therefore higher than that of the forms of the device previously suggested. When the electrode El is inclined to the direction of incidence of the primary electrons, then it is possible to employ a simplified electrode system. Such a simplified system is shown in Figure 3a. The collector electrode El is parallel to or inclined at a small angle to the output electrode 0. On account of the proximity of the electrode to the electrode El, and because the electrode El is more negative than the electrode 0, substantially all the secondary electrons emitted by the electrode El are trapped and are collected by the electrode 0. The secondary electrons emitted by the electrode 0 are, however, substantially all collected by the electrode E3 as in the form of the device shown in Figure 3.

In order to emphasise the remarkable efiiciency of devices of the type herein described, some practical values are here given. Assume:

pr=2 milliarnps 2a=0.5 mm. Ds=2 mm./vo1t A=O 9 11 4 R=20,000 ohms Then:

= 72 milliamps/ volt 0.072 ohm Some possible applications of the device are shown in Figures 5, 6 and '7.

Figure 5 shows an electrical circuit in which a device according to the invention is employed as an amplifier. The form of the device shown in Figure 5 is the same as that of which the output portion is shown in Figure 4. Input signals from I are applied through a suitable tuning circuit J and condenser K to the deflection plate Pl of the device, the deflection plate P2 being earthed. The electron beam is deflected under the influence of the input signals across the active edge Z of the output electrode 0. This produces amplified signals on the output electrode which are communicated to one end of the tuned circuit T, the other end of which is earthed for the input signal frequency through the condenser Kl. The tuned circuit T forms the output impedance of the device. Output signals may be obtained from the terminals L of the tuned circuit T.

The potentials required for the cathode C, the grid G, the anodes Al and A2, the plate P2 and the electrode system El E2, E3, E9, are obtained from the potentiometer W which is fed by a power supply unit (not shown) The auxiliary potentiometer system FHDB supplies the direct current Instead of the tuned circuit T, any suitable load impedance may be employed, viz. a pure inductance, an ohmic resistance, a capacity, or any combination of these. It should also be appreciated that, for the purpose of circuits such as that shown in Figure 5, the electrode system El, E2, E3, E9, the plate P2, and the anode A2 may all be connected inside the valve. Thus five terminals at the base of the valve, supplying respectively the above-mentioned interconnected electrode system, the first anode Al, the grid G, and the two sides of the cathode C, are sufficient with the addition of an input connection to the plate PI and an output connection to the output electrode O. The volume control obtained by defocussing the electron beam can be effected by adjustment of the potential tap VI to which the first anode Al is connected. In order to prevent modulation hum due to the cathode not being earthed, it is possible to earth the cathode instead of the second anode A2 and the electrodes connected thereto, this latter system being decoupled to earth through condensers.

Figure 6 shows a circuit wherein a device according to the invention is employed as a detector. When the device is used as a detector, the electron beam should pass just clear of the active edge of the target electrode when no input signal is applied to the device. An input signal then deflects the beam so that it falls on the target electrode during one half of each cycle of the input signal, thereby producing a half-wave rectified signal on the target electrode. If a pair of target electrodes is employed disposed symmetrically about the position of the electron image in its undeflected position, a half-wave rectified signal is produced on the respective target electrodes by opposite halves of the input signal, and these two half-wave rectified signals may be combined into a full-wave rectified signal. In Figure 6 a device of this form is shown.

The circuit of Figure 6 is essentially similar to that of Figure 5, but a pair of target or output electrodes Ol 02 is employed in the electronic valve device. The supply potentiometer shown at W in Figure 5, and the connections to the electron beam-producing and focussing means, have potential of the plate PI, and also provides a been omitted in Figure 6 for the sake of clarity, but the points marked F, B in Figure 6 correspond to the points similarly marked in Figure 5. The output impedances TI and T2 associated with the output electrodes Ol and 02 are shown in Figure 6 as resistances, but any other suitable impedances may be employed. KM and K42 are decoupling condensers for variations corresponding to the high frequency carrier of the input signals. One end of the resistances TI and T2 is connected respectively to the point D! and the point D2, with the necessary decoupling condensers KH and Kl2 for decoupling low-frequency variations, of the auxiliary potentiometer systems FHIDIB and FH2D2B, which correspond to the potentiometer system FHDB of Figure 5. The points HI and H2 are connected with the necessary decoupling condensers K2l and K22 through the resistances RH and Rl2 to the plates PI and P2 of the device, just as the point H is connected to the plate Pl in Figure 5. The input signals from I are applied through condensers KOI and K02 symmetrically on to the deflection plates PI and P2 of the device. The electron beam is thus deflected symmetrically over the output electrodes Ol and'O2, producing across each of the output impedances Tl, T2 half-wave rectified signals. These signals are fed through the condensers K31 and K352 respectively to any point, where these rectified signals may be required, producing at'that point full-wave rectified signals. In the circuitshown in Figure 6 they are applied to the grid GX of a thermionic valve amplifier X, which may be an output valve of a radio receiver. The

circuit of Figure 6 represents a rectifier having an ideally straight characteristic which may at the same time produce a great amplification of the input signals.

Figure 7 shows a circuit-in which a device according to the invention is employed as a frequency changer. The input signals from I, con.- sisting of a modulated carrier, are applied through the tuned circuit J and the condenser K to the deflection plate PI of the device. This, and the connections to the device, are the same as those shown in Figure 5, except that it is convenient to earth the cathode and to decouple the second anode and-its associated connections to earth through the condenser KID. The supply potentiometer W and the auxiliary potentiometer FI-IDB, and the connections to the electron beam producing and focussing electrodes shown in Figure 5 have been omitted from Figure 7 for the sake of clarity, but thepoints D and H marked in Figure 7 correspond to the points similarly marked in Figure 5. An additional carrier oscillation of constant amplitude is produced by an oscillator Y and fed on to a deflection plate of the device. This might be the plate P2, but in Figure .7 it is shown as the plate P4 of an additional pair of deflection plates P3, P4, the plate P3 being maintained at second anode potential. The oscillation of the beam across the output electrode resulting frOm the two carrier signals applied to the deflection plates produces across the output impedanceT, which is advantageously a band-pass circuit, a modulated carrier signal of frequency equal to the heterodyne of the frequencies of the applied carrier signals.

The electrode system constituting the valve S of the oscillator Y may be incorporated in the electron beam valve, and may be either an intensity modulated valve, as shown in Figure 7, or a deflection modulated valve.

Figure 8 shows a circuit wherein a device according to the invention is employed as an oscillator. Figure except that the input circuit IJK (Figure 5) is replaced by a feed-back unit Q linked with the output impedance T and applied symmetrically across the deflection plates Pl, P2. In Figure 8 an inductive feed-back is shown, but alternatively the feed-back may be resistive or capacitative. The supply potentiometer W shown in Figure 5 and the associated connections to the electrodes of the electron beam device have been omitted from Figure 8 for the sake of clarity.

What we claim and desire to secure by Letters Patent is:

1. An electronic valve device comprising means for producing an electron beam, means for focusing the beam to form a narrow elongated electron image, output electrode means having an active edge parallel to the length of the electron image, means for deflecting the beam across the active edge of said output electrode means to produce signal potentials thereon, and an auxiliary electrode system adjacent said output electrode means; said auxiliary electrode system including collector electrode means upon which that part of the electron beam impinges which does not impinge on the output electrode means, and an elec trode through which the electron beam can pass The circuit is similar to that shown in v disposed in the path of the electron beam to said output electrode means and said collector electrode means, whereby the respective transfers between said electrode means of secondary electrons resulting from the impact thereon of the electron beam may be controlled by adjustment of the energizing potentials of the auxiliary electrode system relative to the energizing potential of the output electrode means.

2. An electronic valve device as recited in claim 1, wherein said auxiliary electrode system includes an electrode between said output electrode means and said collector electrode means, said last electrode being adapted to be maintained at a potential more negative than the potentials on the respective electrode means, whereby the transfer of secondary electrons from either electrode means to the other is substantially prevented.

3. An electronic valve device as recited in claim 1, wherein said collector electrode means and said electrode of said auxiliary electrode system have independent connections for the application of different energizing potentials, whereby adjustment of the potential of the output electrode means to a value greater than that of the collector electrode means and less than that of said electrode results in the collection by said electrode of substantially all secondary electrons emitted from said output electrode means and in the collection by said output electrode means of substantially all secondary electrons emitted by said collector electrode means.

4. An electronic valve device as recited in claim 1, wherein said collector electrode means and said electrode of said auxiliary electrode system have a common connection for impressing an energizing potential upon the same.

5. An electronic valve device as recited in claim 1, wherein the secondary emission coefficient of the output electrode means is less than unity,

whereby the electron beam charges the output electrode means in a negative sense.

6. An electronic valve device as recited in claim 1, wherein the secondary emission coeflicient of the output electrode means is greater than unity, whereby the electron beam charges the output electrode means in a positive sense.

7. In an electron discharge device of the type including means for producing an electron beam, means to focus the beam to form a narrow elongated electron image, deflection means for oscillating the electron image at a signal frequency, and electrode means across which the electron image is oscillated by said deflection means; said electrode means comprising an output electrode having an active edge parallel to the elongated beam image, a collector electrode for receiving the part of the beam image not intercepted by said output electrode, and an electrompermeable electrode in the path of the beam to said output and collector electrodes, said output and collector electrodes having secondary emission coefficients greater than unity and both said collector electrode and said electron-permeable electrode being adapted to be by-passed to said beam producing means for potentials of signal frequencies; whereby the charge developed upon the output electrodedepends upon the efiects of secondary electron emission as controlled by the relative magnitudes of the energizin potentials impressed upon the several electrodes.

8. In an electron discharge device, an electrode means as recited in claim 7, wherein saidoutput electrode has an active surface at an angle oblique to the direction of incidence of the electron beam and located between said collector electrode and said electron-permeable electrode, the two latter electrodes being normal to the mean path of the electron beam.

9. In an electron discharge device including means for oscillating a focused electron beam of narrow elongated cross-section in response to impressed signal voltages, an electrode assembly comprising an output electrode inclined to the path of the electron beam and having an active edge across which the beam is oscillated, a collector electrode for receiving the part of the beam not intercepted by said output electrode, and a constant potential electrode positioned laterally of said output electrode, whereby potential variations developed on said output electrode by the signal-produced deflection of the beam operate in conjunction with the constant potential on said laterally-positioned electrode to effect a secondary deflection of the beam.

10. In an electron discharge device, an electrode assembly as recited in claim 9, wherein said laterally-positioned electrode has a potential that is positive with respect to said output electrode, and said output electrode has a secondary emission coefficient less than unity, whereby said secondary deflection opposes the signal-produced deflection of the electron beam.

11. In an electron discharge device, an electrode assembly as recited in claim 9, wherein said laterally-positioned electrode has a potential that is positive with respect to said output electrode, and said output electrode has a secondary emissio-n coefiicient greater than unity, whereby said secondary deflection increases the signal-produced deflection of the electron beam.

12. In an electron discharge device, an electrode assembly as recited in claim 9, wherein said output electrode has a secondary emission coefficient greater than unity, and said constant potential electrode is located at the side of said inclined output electrode opposite to the path of the deflected electron beam to the collector electrode, whereby the secondary deflection opposes the signal-produced deflection of the beam when the constant potential electrode is positive with respect to said output electrode,

13. In an electronic discharge device, means for producing an electron beam, means for focusing the beam to form a narrow elongated electron image, deflecting means for displacing the beam electron beam in the undeflected at right angles to the length of the electron image, output electrode means having an active edge parallel to the beam image and just clear of the electron beam in the undeflected portion thereof, a collector electrode upon which the undeflected beam impinges, and an electron-permeable electrode in the path of the beam to said output electrode means and said collector electrode, the deflection of the beam by signals impressed on said deflecting means producing a half-wave rectified signal potential on said output electrode means.

14. In an electronic discharge device, the invention as recited in claim 13, wherein said output electrode means comprises tWo target electrodes having adjacent edges parallel to the electron image and spaced apart to just clear the position thereof, alternate half-waves of rectified signal potentials being developed on the respective target electrodes.

15. In an electronic discharge device, means for producing an electron beam, means for focusing the beam to form a narrow elongated electron image, deflector electrode means upon which signals may be impressed to oscillate said beam at right angles to the length of the electron image, an output electrode having an active edge parallel to the length of the electron image, a, collector electrode upon which impinges the part of the beam not intercepted by the output electrode, and an'electrode through which electrons can pass located in the path of the beam to said output and collector electrodes, said collector electrode and last electrode being by-passed to ground for potentials of signal frequency.

16. In an electronic discharge device, the invention as recited in claim 15, wherein said collector electrode is inclined to the path of the elec-- tron beam and has a secondary emission coefficient greater than unity.

1'7. In an electronic discharge device, the invention as recited in claim 15, in combination with means for controlling the amplitude of the signal potentials developed at said output electrode, said amplitude-controlling means comprising an electrode for varying the width of the electron image in accordance with changes in the energizing potential impressed on that electrode.

PAUL NAGY. MARCUS JAMES GODDARD.

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