US2172859A - Electron tube circuits - Google Patents

Description

P. M. G. TOULON ELECTRON TUBE CIRCUITS Original Filed May 27, 1936 Sept. 12, 1939.

s Sheets-Shed: 1

Sept. 12, 1939. P. M. s. TOULON 2,172,359

ELECTRON TUBE CIRCUITS Original Filed May 27. 1936 3 Sheets-Sheet 2 I win i 39 2 I INVE/V roR 32m; in; GZIAMWAM atented Sept. .112, 11939 STTES ELECTRON E CHRCUI'ES Pierre Marie Gabriel Toulon, lPuteaux, France,

assignor to Hazeltine Corporation, a corporation of Delaware Original application May 27, 1936, Serial No.

Divided and this application January 6, 1937, Serial No. 119,317. In France May 31,

10 Claims.

The present invention relates to a new electronic tube circuit, in which a plurality of grids and a plurality of plates are arranged symmetrically and allow control of the anode ourrents which are independent of the electronic emission furnished-by the cathode. Such tubes form the subject of my copending application Serial No. 82,131, filed May 27, 1936.

The control of an electronic current has already been efiected in numerous ways with the .aid of one or more grids in an evacuated tube.

' Whatever the system hitherto employed (electrostatic or electromagnetic control of the electrons), the totalquantity of electrons escaping is from the cathode is not constant at all times but depends upon the instantaneous voltages applied to the control grids or to the anode, that is, upon the operating conditions of the tube. This irregularity in the out-put emitted by the cathode presents numerous drawbacks. In particular, the plate supply system is subjected to the efiects of the control grid and of the impedance of the circuits, so that the space charge is not constant. In multi-electrode tubes in particular, where it 5 is sought to accomplish several consecutive effects by means of a single cathode, as is the case with frequency-changing or mixing tubes, it is necessary, in order to avoid the interaction-between the difierent circuits, to add tothe control and utilising electrodes, protective electrodes or screen-grids, which reduce the harmful eiiects of these reactions, without, however, completely avoiding them.

Various circuits have already been proposed which employ several associated tubes (pushpull circuit for instance) and which partly avoid this defect from the point of view of the external reactions of the tube, but at the cost of a multiplicity of tubes, the characteristics of which must be exactly matched. In any event, the internal reactions of the tube, that is, the space charge, the variation of plate impedance etc., are not corrected in this manner.

The present invention has for object a new 4 method which allows of effecting the control of a plurality of electrodes of a tube by means of other electrodes, without creating external disturbances and, in particular, without causing the intensity of the electronic flux escaping from the cathode to vary, and without creating any variathereof. The description-of an elementary tube has been given in French Patent No. 774,752 of the Compagnie Francaise Thomson-Houston, filed June 19, 1934. It is known that, in these tubes, an amplifier can be obtained by making. 5 use of the deflecting plates of a tube with a cathodic beam to cause the cathodic beam to impinge on or deviate from the anode. However, contrary to what has been done up to the present day, when the deflecting and collecting electrodes were arranged in the tube without any thought of balance and acted both as deflecting and retarding electrodes (which had the effect of creating internal and external reactions), according to the invention, the deflecting electrodes are arranged in such a manner that their effects have a zero resultant outside the system, that is, any efiect produced in a certain sense on one group of electrodes will be opposed by an effect of opposite sign on another group. Thus, the space charge of the tube is not modified, the total plate current remains constant and the same is the case with the grid current and with the other characteristics of the tube which remain independent of the working conditions.

The objects and the scope of the present invention will be better understood by reference to the accompanying drawings, which represent some particular ways of carrying out the new method..

Fig. 1 serves to illustrate the well-known prop erties of the push-pull circuit. I

Fig. 2 serves to illustrate some properties of the deflecting electrodes of the tubes known up to the present day.

Fig. 3 illustrates the manner in which the new method, forming the object of the invention, provides, with a single tube, a circuit having properties similar to that of Fig. 1 and employing the principle of the deflecting electrodes. 40

Fig. 4 gives a theoretical explanation'of the operation of this tube.

Fig. 5 illustrates the application of the new method to a frequency-changing tube.

Fig. 6 illustrates the application of the new method to a tube with a multi-mu characteristic.

Fig. 7 shows how it is possible to obtain in a single tube a. large number of independent amplifying stages.

Fig. 8 illustrates how it is possible to employ the new method for the complete lay-out of a radio set with a single tube.

All these figures are given only by way of example, as it is quite obvious that the new method near the first.

In Fig. 1, the tube with three electrodes 2, 3,

5 allows o-f amplifying a weak current furnished by the input circuit i and of obtaining a substantial corresponding current in the output circuit 5 in accordance with the well-known invention of de Forest. If there were no second tube comprising electrodes ii, 9, II the platevoltage battery 6 would be affected by the variations of the current in the external circuit 5. These variations also affect the emission of the cathode 4. on the supply circuit, it has already been proposed to arrange a second tube, such as 8, 9, ll, Arrangements are made so that the input circuit I of the second tube is fed in phase opposition to that of the circuit I. Under these conditions, the external current I is also in phase opposition to 5. If the two tubes are identical from the point of view of their construction and if the voltage of the grid 2 is continually equal and opposite to that of 8 with respect to a neutral point or to a suitably chosen biassing point, the total current in the external circuits and ID (in the case where the tubes are not saturated) remains almost constant, and the modulation of the system is without harmful effect on the supply circuit 6, that is, the battery does not suffer the consequences of the modulation. This principle of balancing is applied, in accordance with the invention, to

tubes containing deflecting electrodes, that is,

electrodes having the sole function of deflecting the paths of the electrons and not retarding or stopping them (as was originally done in the de Forest tubes). Owing to the juxtaposition of the two phenomena in a single envelope, it is possible not only to avoid the reactions on the external circuit and on the battery, such as 6, but to combine the cathode such as I and II and consequently avoid the reactions of the operation on the space charge of the envelope.

'Fig. 2 servesto illustrate the principle of the deflecting electrodes employed up to the present day. Given a cathode ll, an anode l3 brought to a positive potential and" formed by a grid, and a second anode 12 also brought to the same positive potential, it is known that the introduction of a grid l4 between the electrodes l2 and it] allows of varying the ratio of the currents furnished by the electrodes l2 and [3 as a. function of the potential of the electrodes ll. This fact is explained by saying that the variation of the potential of the deflecting grid I4 modifies the space charge in the interval between the grid 84 and the electrode it, that there is an increase in the dimensions of the neutral zone l5 surrounding the meshes of the grid M in proportion to the amount by which the electrodes become moremegative and that there is a reduction of the zone it available for the passage of the electrons emitted by the filament H and sent through the meshes of the grid M;

In such a tube, the current furnished by the cathode varies by a relatively small amount when the voltage of the deflecting grid is varied, as the diminution of the current furnished by the electrode i2 is partly compensated by the increase in the output of the electrode 63. However, this compensation is only rather moderate, as the considerable asymmetry which exists between the electrodes it and it gives them ex- To avoid the reactions of the tube tremely different characteristics (internal resistance, amplification factor, etc.). In practice, it is sufficient to bring the electrode i3 to a fixed potential, the electrode l2 being the onlyv one which feeds the external circuit. In fact, the electrons leaving the filament H' and having passed through the meshes of the electrode l3 must return into contact with the electrode i3 after having approached the defleeting electrode I I, that is, the path of the electrons must be reversed in one case, while, on the contrary, those which reach the electrode i2 continue their path in a straight line, thus contributing in a. large measure to increasing the asymmetry of the electrodes I2 and I3. However, in practice, the advantages of such a tube will be appreciated, as the current furnished by the cathode varies relatively little when r the voltage of the deflecting grid is varied, and this advantage has rendered great service in radio-set practice. The diminution of the current furnished by the electrode [2 is, in effect, partly compensated by the increase in the output of the electrode l3, and the space charge varies relatively little. However, the compensation is not perfect and the considerable asymmetry in the position of the electrodes l2 and I3 renders the method doubtful in efllciency.

It has also been proposed to employ the principle of the cathode oscillograph, that is, to employ two balanced deflecting electrodes (see French Patent No. 774,752 already mentioned). The use of a single working anode, however, does not cause the asymmetry of the system to disappear. On the other hand, the very great distance which separates the cathodes from the anodes in the apparatus described necessitates the use of very high voltages, and the system is hardly practical for producing an amplifier.

According to the invention, there is arranged between the cathode and the anode, not a single deflecting grid, as has hitherto been done (or two deflecting plates of a cathode oscillograph) but two deflecting grids arranged in spiral form side by side, the difierent successive meshes being intertwined. These two deflecting grids alternately furnish an action ofopposite sense. Theanodes arranged opposite these deflecting electrodes are also two in number and are placed in a symmetrical manner. The modulation is eifected by the fact that the difl'erence of potential introduced between the two deflecting grids modifies the distribution of the charges which respectively fall on the two anodes. Given, on one hand, that none of the deflecting grids receives electrons and given, on the other, that the whole of the electrons which have left the oathode impinges on the anodes, the sum total of the currents of these anodes remains constant. If these anodes have a space between them which allows certain electrons to escape, the quantity which passes the two anodes also remains constant and independentof the modulation.

The description given above in the case of two anodes and two deflecting grids may also be applied to the case of a large number of anodes and a large number of deflecting grids.

As is shown in Fig. 4, the cathode ii emits electrons; these are accelerated by means oi a first auxiliary grid 9 for example, which they clear at great speed. From this moment, the electrons are guided and have a well-determined direction. With the aid oi even a weak electrostatic field, it is possible to deflect their path.

This is precisely the object of the intertwined I deflecting electrodes I8 and IS. The most conby the black spots, is brought to a positive potential, the emitted electrons tend to approach it, If, at the same time, the'other grid I9 (represented by white spots for the clearness of the figure) is brought to a negative potential, the electrons tend to digress therefrom. At the anode 2i arranged behind the meshes of the grid I8 there is convergence; on the contrary, there is divergence at the meshes of the anode 22. In other words, the current tends to be solely furnished by the anode 2|, and the current tends to disappear in the anode 22. However, the sum total of the currents 2| and 22 remains substantially constant, so that the current furnished by the cathode is not aifected by the modulation, as was the case with the nonsymmetrical tubes hitherto provided.

Fig. 3 shows how the new system of deflecting electrodes provides a push-pull amplifying circuit similar to that in Fig. 1. 24 introduce-the modulation between the two deflecting grids (as is done by the coils I and I of Fig. 1). The amplified current is utilised in the coils 25 and 26 (in the same way as the coils 5 and Ill in Fig. 1) but the two systems are placed in the same envelope. However, the cathode 4 was not afiected in the same manner as the cathode I I at each instant of the modulation, whereas the cathode IT is not subjected to the influence of the modulation.

Fig. 4 serves to illustrate the trend of the action of the modulation eflected by the intertwined deflecting grids according to the invention. The path of the electrons has been represented by dotted lines and the same elements as in the case of Fig. 3 have been denoted by the same references. Le't us assume that the grid I9 is more negative than the grid I8; as the figure shows, the path of the electrons is'deflected by its passage across the modulating grids. The anode 2i, which is situated in a zone of concentration, receives more electrons than the anode 22, which, on the contrary, is situated on a zone of low electronic density, but the total output-of theelectrons emitted .by the cathode remains constant, although each anode receives a diiferent number of electrons and the modulation is therefore amplified. On the other hand, the number ,of electrons which have.

cleared the meshes of the anode grids is not affected by the internal modulation at the anode and this allows of subsequently utilising them for a new purpose.

With the above-described arrangement of the elements, the two control electrodes It, IS -iunction to separate the electrons flowing toward the anodes 2|, 22 into a plurality of streams. For example, each turn of each of the helical anodes and control electrodes may be considered to be a section of the electrode of which it forms a part; the several sections, or turns, being connected together at their ends to form a\ continuous element. As thus considered, the helicoidal path extending substantially perpendicularly from the cathode and between each adjacent pair of single turns of the two control electrodes may be described as constituting a The coils 23 and be seen to be parallel to the path of the stream flowing in the he'licoidal path perpendicular to the cathode and extending between the next adjacent pairs of single turns of the control electrodes. v

It will be understood that the term section appearing in the appended claims is used in its broad sense to denote one of the elemental components of any form of electrode. For example, in the helical form described, even though the electrodes are actually continued helices and the "electron stream is actually continuous, to aid in the analysis of the operation of the tube the electrodes may be considered to comprise a plurality of elemental turns or sections and the electron stream may be considered to be made up of a plurality of substantially annular streams bounded by the adjacent sections of the two electrodes. In such a structure, the term section" thus refers to a single elemental component or turn.

As is shown in Fig. 5, the invention can be applied to a frequency-changing heterodyne tube. The deflecting grids 28 and 29 and the symmetrical anodes 35 and 36 contribute to sustaining the heterodyne oscillations. For this purpose, the grids 28 and 29 are connected to an oscillatory circuit 30, 3| and 32. The anodes 35 and 35 are connected to coils 33 and 34 coupled to this oscillatory circuit. Moreover, the voltage of the assembly of deflecting grids 28 and 29 may be modified, for instance, by means of a coil 4| coupled to an oscillatory wave-receiving antenna-earth circuit 42. This modulation of the assembly of grids 28 and 29 allows of controlling the plate current and thus obtaining an amplification which is completely independent of the modulation, while employing the same tube. The plate 38 receives the current which has passed through the anode 35 and 36. By arranging a grid such as 31, coupled by a condenser such as 44, to the heterodyne oscillatory circuit, the change of frequency can be effected in the same tube, and a suitably tuned oscillatory circuit 43 eventually facilitates coupling. The intermediate-frequency oscillatory circuit 38 is connected to the anode 38.

Fig. 6 illustrates the possibility of application of the new tube for the purpose of obtaining a variable amplification factor. The cathode 41 emits electrons which are deflected by means of two independent sets of electrodes 48-49 and Ell-5|. trolled by means of the input circuit 46, and the external circuit 56 is connected to the plate 55.

The amplification factor of the tube may be varied by modifying the potential of the electrodes 58 and 5| with respect to that of the electrodes 48 and 49. When the electrodes 48 and 50 are brought to the same potential, the amplification factor of the tube is a maximum; vice-versa, if the potential of the electrodes50 and 5| is increased with respect to that of the electrodes 48 and 49, the amplification factor of the tube is greatly reduced.

Fig '7 shows how it is possible to obtain in a single tube a plurality of stages of independent amplifications, In this figure, the wave-receivingsystem is shown at Ell-6|. The cathode 51 emits electspns. The two grids 64 and 65, which are suitablymegatively biased by the battery 58, serve as deflecting electrodes. A potential difference is applied between the two deflecting The assembly of grids may be con-- electrodes 64 and 65 by means of an oscillatory 7 5 circuit 62-93 coupled to the antenna-earth circuit 60, st. The first stage of amplification is obtained with the aid of the anodes 66 and 61 connected to the oscillatory circuit 6869. The electronic flux which escapes through the anodes 66 and t'i is strictly constant according to the invention. It is thus possible to place in succession to this first stage a second stage of amplification comprising the grid I connected to an oscillatory circuit Ii coupled to the circuit 68-59. The plate I2, which is connected to the output circuit l3, thus receives the energy proceeding from the oscillatory circuit 60-6I and amplified twice.

Fig. 8 illustrates by way of example and in order to show the diversity of application of the invention, how it is possible to employ the new method for the complete lay-out of a radio set with a single tube. Between the cathode IM and the main anode 99 there are alternately arranged groups of deflecting electrodes and of suitably distributed anodes. The oscillatory antenna-earth circuit 15 coupled to the circuit '36 acts on the first group of deflecting electrodes iI-I8 which are suitably negatively biased by the battery I I4. The first group of anode I9--80 receives the energy, suitably amplified, in the oscillatory circuit I00. The heterodyner is arranged between the two grids 8i and 86. This heterodyner is formed by the deflecting electrodes 82 and 83 connected to the oscillatory circuit I06 and by the collecting anodes .84 and 85 connected to the coupling coils I05. The grid 8|, which, through coil I03 receives the amplified modulation proceeding from the antenna-earth circuit, supplies this signal energy to the oscillation section comprising grids 82, 83 wherein, by means of electrodes 84, 85, it is modulated by the high-frequency oscillations and appears at grid 06 as intermediate-frequency energy. Owing to the oscillatory circuit IDS-I01, the deflecting electrodes 87 and 88, with the anodes 89 and 90, efiect the intermediate-frequency amplification. The energy is then detected by the system l08-IIO. A first stage of amplification at low frequency is then provided by the defiecting electrode 9293 and 94-95. The energy at low frequency is finally amplified by the grid 91. The plate 99 transmits the amplified low frequency energy to the loudspeaker H2.

The grids 9 6, 98 and H3 are brought to a positive potential and serve as screens.

It is easy to understand that in this manner the reaction between the different. stages of amplification which are combined in the same tube is completely avoided, and that the new method of the invention allows of obtaining in a single envelope any number of stages of amplification and as complicated a connection as desired.

I claim:

1. Electronic tube arrangement, comprising an emissive cathode, a plurality of interleaved control electrodes, a plurality of interleaved electroncollecting electrodes, the two groups of electrodes being arranged facing each other, and a grid arranged between the cathode and the control grids, this grid being brought to a constant positive potential with respect to the cathode and serving to accelerate the electrons.

2. Electronic tube comprising a cathode, two intertwined helical grids, two further intertwined helical grids arranged at a greater distance from the cathode and brought to a positive potential with respect to the cathode, means for applying alternating potentials of the same amplitude and of the same sign with reference to the cathode to the first two grids, and means for applying to the same grids alternating potentials of the same amplitude but of opposite sign.

3. Electronic tube arrangement comprising a cathode, two intertwined deflecting grids and two further intertwined collecting grids arranged at a greater distance from the cathode and brought to a positive potential, with respect to the cathode and means for equally biasing the deflecting grids with respect to the cathode.

4. Electronic tube arrangement comprising two interwined deflecting grids and two intertwined collecting grids, means for applying a higher potential to the collecting grids than to the deflecting grids, a circuit associated with the deflecting grids, a circuit associated with the collecting grids, and means for back-coupling the circuit of the collecting grids to the circuit of 'the deflecting grids.

5. Circuit comprising a tube consisting of a cathode, two intertwined deflecting grids, two intertwined collecting grids arranged at a greater distance from the cathode, a plate brought to a positive potential with respect to the cathode and arranged beyond the collecting grids, at last one additional grid arranged between said plate and said collecting grids, and means for varying the potential of said additional grid so that it modulates the intensity of the electronic stream traversing it.

6. Circuit formed by an electronic tube comprising a cathode, at least two grids placed in the path of a single electronic flux emitted by said cathode and traversed simultaneously by this flux, at least two electron-collecting electrodes simultaneously receiving the electrons, means for applying to said grids different potentials with respect to the cathode so that the electronic flux undergoes a deflection, means for deriving from said collecting electrodes an external current, the value of which varies in accordance with variations in the potentials of the deflecting grids, and means for varying the potentials of the deflecting grids simultaneously and in like manner so as to cause the sum total of the currents received on the collecting electrodes to vary as a function of these potentials.

7. A circuit containing a tube consisting of a I I cathode producing a single electronic flux, a group of two intertwined deflecting electrodes traversed simultaneously by said flux, a second group of two intertwined collecting electrodes arranged at a greater distance from the cathode than the first group, an electron-collecting plate arranged still further from said cathode and beyond said group of collecting electrodes, an input circuit applying variable potentials of equal amplitude but of opposite sign bctween the deflecting electrodes and the cathode, means for applying to the collecting electrodes equal positive voltages, and a load accordance with variations in the potentials of the deflecting grids.

9. Circuit formed by an electronic tube comprising a cathode, at least two intertwined grids placed in the path of a single electronic flux emitted by said cathode and traversed simultaneously by this flux, at least two intertwined electron-collecting electrodes simultaneously receiving the electrons, means for applying to said intertwined grids different potentials with respect to the cathode so that the electronic flux undergoes a deflection, means for deriving from said collecting electrodes an external current the value of which varies in accordance with variations in the potentials of the deflecting grids, and means for varying the potentials of the deflecting grids simultaneously and in like manner so as to cause the sum total of the currents received on the collecting electrodes to vary as a function of these potentials. v

10. An electronic tube arrangement comprising an emissive cathode, two intertwined helical deflecting grids-two intertwined helical collecting grids having the same pitch as the deflecting grids and surrounding said deflecting grids, a third grid arranged between said cathode and said helical deflecting grids, said third grid being brought to a constant positive potential with respect to said cathode and serving to accelerate the electrons.

PIERRE GABRIEL TOULON.

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