US2259099A - Electron discharge tube - Google Patents

Description

Oct. 14, 1941. J. BERNAMONT ELECTRON DISCHARGE TUBE 2 Sheets-Sheet l Filed June 24, 1959 Fig. 2.

Atto/nea Fig. 3.

' Oct. 14, 1941. J. BERNAMONT ELECTRON DI S CHARGE TUBE Filed June 24, 1939 2 Sheets-Sheet 2 Eljatentecl Oct. 14, 1941 UETED STTES PATENT GFFICE ELECTRON DISCHARGE TUBE Application June 24, 1939, Serial No. 280,927

In France June 25, 1938 (Cl. Z50- 151) 2 Claims.

The present invention relates to electron discharge tubes and particularly to electron discharge tubes adapted to serve as electronic relays or oscillographs.

The main object of the invention is to provide electronic relays and oscillographs particularly to operate at very high frequencies.

IThe use at very high frequencies of an ordinary electronic relay is, in effect, limited in the case of aperiodic amplification by the fact that the capacities of the oscillating electrodes of the device must be loaded through the relatively high impedances which connect these electrodes to the cathode. In designating by P the slope of the tube, by C the capacity of the anode-and elements directly associated therewith, it can be shown that the aperiodic amplilication cannot take place in the absence of reactive action of the anode circuit on the control circuit, for any frequency greater than mP/C, m being a numerical co-efcient which depends on the precision with which it is desired to obtain the aperiodicity of the amplification. l

One object of the invention is consequently to provide electron discharge tubes of which the slope is of high value by construction, although the capacity of the anode with the cathode is small so as to permit the aperiodic amplication of very high frequencies.

Another object of the invention is the obtainment of an aperiodic amplifier occupying little space and simple to mount, in the form of a ksingle electronic relay, or of a number of these which is small in respect of the amplification to be obtained.

Another object of the invention is to obtain an aperiodic amplifier Without distortion.

Another object of the invention is to ob-tain a highly sensitive oscillograph tube.

Another object of the invention is to produce currents of particular forms, such as crenellated current, saw-tooth current, etc., from relatively low alternating potentials.

Another object of the invention is the frequency multiplication and the production of intense oscillatory currents from 10W tensions and powers. Y

The invention provides in a general manner the association of the 'control ci an electronic beam by electrostatic and/or magnetic deviation, and of an electronic-optical device with a View to amplifying the displacement of the beam.

In accordance With one of its characteristics, the invention provides electronic beam apparatus or devices comprising means for generating an electron beam, means for deflecting same,

means Vfor amplifying the deflection and means for receiving said beam. 'Ihe meansfor amplifying the deection of said beam may consist of an electronic optical system placed between the deecting means (for example, delecting plates) and said beam-receiving means (for example, an electrode structure) and may consist of one or more electronic lenses.

In accordance with another characteristic of the invention, 'the electronic optical system amplifying thel deflection or deviation of said beam is adapted to amplify the said deviation either symmetrically in two directions -or in one direction only.

In accordance with another characteristic of the invention, said electronic optical rsystem amplifying the deviation of the beam is adapted to amplify said deviation in several successive degrees of amplification, according to any desired combination of symmetrical or asymmetrical amplifications in two or more directionsl or in one direction only.

In accordance with another characteristic of the invention, the said beam-deflecting means are arranged in symmetrical equilibrium with respect to a plane containing a longitudinal axis of symmetry of the receiving structure of said beam arranged so as to offer such an axis of symmetry.,

In accordance with another characteristic of the invention the deecting means of the device comprise at least two semi-cylindrical electrodes which may or may not be in balanced relation, and a cylindrical electrode of the same axis as said semi-cylindrical electrodes, connected so as to produce a first enlargement of the deflected image which may if need be, be followed by other stages of enlargement.

A device incorporating the preceding characteristics maybe used as oscillographic tube, said means for receiving the electronic beam then consisting ofY a fluorescent or luminescent screen.

In accordance With another characteristic of the invention vthe beam-receiving means may in another way consist of two output electrodes on which said beam is successively caused to fall according to the deviation imparted thereto, for example, a perforated electrode placed in front of a plate electrode, a third annular electrode possible being arranged between these two output electrodes. One of these electrodes may consist of an electrode capable of emitting secondary electrons, and Aeven be associated With anelectron-multiplier structure. In another way a single plate electrode may also be used, this electrode being provided so as to offer an emissive power of secondary electrons variable on its surface. I y

In accordance with another characteristic of the invention, an electrode of th system of generation -of the beam, acting as virtual source of the beam and/or an electrode forming a part of said receiving means, are provided in the forni of grids in such a way that the complete apparatus can operate as frequency multiplier.

In accordance with another characteristic of the invention, an electrode of the system of generation of the beam acting as virtual source of the electron beam, and an electrode of the beamreceiving structure are arranged to have openings of superposable shapes. y

In accordance with still another feature oi the invention, an electrode of said beam-generating means adapted to play the part of a virtual source of electrons and an electrode of the beam-receiving structure are provided with apertures of such relative shapes that a predetermined output wave form is obtained.

In accordance with still another characteristic of the invention, the devices incorporating features of the invention may be provided with suppressor grids on the path of the electronic beam.

The invention will be explained in detail in :D

relation to the attached drawings in which:

Fig. 1 shows schematically the general arrangement of an electronic tube in accordance with certain characteristics of the invention; and

Fig. 2 represents a schematic embodiment of the arrangement of Fig. 1;

Figs. 3 and 4 show in longitudinal and crosssecticns an electron tube giving a special embodiment in which the device for deviating the beam is combined with the electronic amplifying device;

Fig. 5 shows schematically the general arrangement of an electron tube incorporating characteristics of the invention and employing a beam-receiving structure in which amplification by secondary emission is provided; and

Fig. 6 shows schematically the general arrangement of an electronic relay tube incorporating characteristics of the invention and employing two electronic lenses inY order to supply amd plified deviation of the electronic beam.

Referring to Fig. 1, a high vacuum cathode ray tube may comprise, as shown schematically, a source of electrons I, an electronic lens 2 for concentrating the electrons emitted by the source I on the aperture of a diaphragm 3 in the form of a slot, for example. The beam passes through the diaphragm 3 and enters the deecting plates 4 and 5 (which might be replaced by any desired electrostatic or electromagnetic combination), and passes through an electronic lens indicated at 6, which gives an enlarged image of the slot of the diaphragm 3 and is adjusted so that this image is produced on the rst anti-cathode electrode I of the receiver system of the beam I--8, this iirst anti-cathode 'I playing the part of diaphragm and intercepting a portion of the electronic beam. The second anti-cathode 8 receives the remainder of the beam.

The dilerence Aof control-potential, which can then be taken extremely small, is applied between the deflecting electrodes 4 and 5, so that the displacement of the image of the slot 3 is amplified by the lens 6. If the slot is struck Ain a homogeneous manner by the electrons from the source I, and if the diaphragm 'I is composed of a plane limited by a straight line parallel to the image of the slot, the intensity of the portion of the beam intercepted by the diaphragm 'I and the intensity of the remainder of the beam received by the anti-cathode 8 both vary linearly, but in inverse direction, in terms of the control potential applied to the plates 4 and 5 as long as the image of the slot is traversed by the edge of the diaphragm 1, which prevents any distortion of the output current. This parallelism of the image of the slot and of the straight line limiting the electrode I could, moreover, be ensured by means of a special electronic lens causing the rotation of the image of said slot. so as to bring it into strict parallelism with the straight line limiting the electrode `I. If the electrode 'I consisted of a plate having an opening in order to ensure the absence of distortions it would be sufficient for the forms of this opening and of the slot of the diaphragm 3 to be superposable.

Fig. 2 shows schematically one manner in which the various elements of the electron tube structure of Fig. 1 may be carried out. The emissive cathode I0 may be heated by a filament 9. An electrode II brought to a suitable potential concentrates the electrons on the slot perforated in the anode I2. The electronic beam then passes between the deflecting elements such as the plates I3 and I4, then inside the cylinder I5 and the cylinder I6. The transition from the cylinder I5 to the cylinder I6 plays the part of a converging electronic lens if the potential of the cylinder I6 is higher than the potential of the cylinder I5. The plate I'I plays the part of the screen 'I of Fig. 1 and intercepts half the beam in the absence of deflecting tension on the electrodes I3 and I4. Behind this plate I'I is arranged another plate I8. One or other of the plates I'I and I8 corresponding to the plates 'I and 8 on Fig. 1 may be used as output electrode or the tWo plates II and I8 may be simultaneously employed, provided that the phase opposition produced by the currents which they receive be taken into account.

The anode or diaphragm I2 can with advantage be brought to a relatively ylow potential with respect to the electrodes I6, II and I8, so as to obtain a high sensitivity of the apparatus. 'I'he electrode I5 will then be brought to an intermediate potential between those of the electrodes I2 and IB. Y

There is shown in Figs. 3 and 4, in longitudinal and transverse section respectively, an embodiment of an electron discharge device particularly suitable as electronic relay and incorporating certain characteristics of the invention. The arrangements shown in these drawings comprise an envelope 50 in which vacuum has been made, terminated at both ends by two moulded feet 5I and 52, through which respectively pass the connections 53 for the cathode in the form of directly heated filament I9, 54, for the semicylindrical deecting electrodes 28 and 2| and 55 for the electronic optical elements 22 and 23, through. Ifthe moulded foot 5I, and the@ connections 56 on an output electrode 26 through another foot 52. Moreover, through the foot 5I there passes a connection 51 for an auxiliary electrode 25 of the receiver system of the beam. A lateral electrode connection 58 is provided for another electrode 24 of the electron receiving structure. Two or more longitudinal rods 59 and A{il} may be employed to maintain the various electrodes, for example, by means of insulators such as 6|, these rods being shown brought to acertain potential, which is that of the electrode 25. The electronic beam produced by the cathode I9 passes directly between the sexni- cylin'drical deecting plates 20 and 2|, then inside the cylinder 22 insulated from the cylinder 23 brought to a different potential, but mechanically connected to the cylinder 22 as shown at 62. In the same way the cylinder 22 is mechanically connected to the half cylinders 20 and 2l as shown at 63. In this way a unitary structure of deviation and amplication is obtained. `The electronic beam then passes through the first output electrode 24, in the form of a disc having a large opening, and strikes on the plate 2S. The latter in the case in which no deecting potential is applied to the plates 20 and 2i. The opening of the electrode 24 is larger than the enlarged image of the iiiament I9 given by the electronic system acting as objective 2B, 2l, 22, 23. When the electronic bundle is aperiodically divided by the potential applied to the semi-cylindrical electrodes 20 and 2|, a portion of the beam will be collected by the electrode 24 and the other portion by .the electrode 2S.

Either of the electrodes 24 and 25 may be employed as output electrode, or the two electrodes may be simultaneously employed, taking into consideration the phase opposition of the currents reaching them. A tubular electrode 25 terminated at both ends by a plate, perforated with a rather larger aperture than that of the electrode 2, separates the two electrodes 24 and 26, and prevents the harmful effects of the secondary emission of the plate 2B on the electrode 24, by being brought to a potential lower than that of these two anodes 24 and 26. For

the same reason it is well to bring the electrodes 23 to a lower potential than that of the anode 211.

In the embodiment shown, the receiving structure of the electronic beam composed of the electrodes 24, 25 and 26 has a longitudinal axis of symmetry with respect to the complete electrode structure. Moreover, the deiector system 20, 2i, has a symmetry with respect to a plane containing this axis of symmetry of the receiving structure. On account of this arrangement any retroactive action of the amplified potential in the control potential is avoided, since the rst acts in parallel to the axis of the system, while the second acts perpendicularly to the axis. Another example of an electron discharge tube incorporating characteristics of the invention is shown schematically in Fig. 5, in which, at the end of an electrode structure similar to that of Fig. 1, the anticathode 8 is covered with a substance producing secondary electrons; the cylinder 2l which serves as output electrode is brought to a higher potential than the electrode 8. The cylinder 2l only receives the secondary electrons emitted by the anti-cathode 8 and an additional amplification of the control potential is thus obtained. Several stages of secondary emission may also be employed. In another way the electrode may be employed as electrode with secondary emission. In still another manner the terminal electrode structure may consist of a single electrode, the surface of which has been sensitised in order to produce secondary electrons variable in number according to the point struck by the primary electrons.

Such electron beam devices have in particular the advantage of having a high slope and, moreover, their ouput current control potential characteristic is a straight line which intersects the axis of the abscissae at a definite point, which permits a rate of modulation in the vicinity of 100% even for extremely low potentials to be amplified, and an almost `complete absence or distortion.

Fig. 6 shows the manner in which, in accordance with one characteristic of the invention several successive electronic lenses may be employed to amplify the deflection of the beam. The lens 6 gives a nrst image of the slot of the diaphragm 3 in the plane 29. The lens 2B gives a second enlarged image of this rst image in the plane of the rst anti-cathode 'I forming a diaphragm. Behind the rst anti-cathode 'l a second anti-cathode 8 has been shown as in the case oi Fig. 1, but it is clear that any other electrode terminal structure might be employed.

The ray 30 coming from th-e plane of the slot of the diaphragm 3, and passing through the optical centre of the lens S, strikes on the screen 1. When a control potential is applied between the deecting plates 4 and 5 the ray 3l, coming from the same point as the ray 30 and passing .through the optical centre of the lens 8, strikes on the anode 8. i

It is also possible to provide, in order to amplify the deflection of the electronic beam, two or more electronic lenses between the deecting plates and the receiving structure of the beam, which may or may not be associated with a receiving cathode supplying an output current amplication by successive secondary electron emissions.

It is also clear that cathode oscillographs may be obtained in accordance with characteristics o1 the invention. The electron receiving structure will then consist of a fluorescent or luminescent screen. The deviation in accordance with two dimensions may be obtained by employing two pairs of deecting plates, for example, arranged at from each other, and a fine hole instead of the slot of the diaphragm 3. In such an oscillograph a rst virtual image is formed in a plane which is not that of the terminal screen, then an. electronic objective, inserted between the derlecting plates of the terminal screen, forms on the latter an enlarged image of this virtual image.

In this way oscillograph tubes of high sensitivity without preliminary amplification of the deecting potential and capable of faithfully following variations of very high frequencies, may be obtained.

In the tubes described and shown deflecting plates have been described by way of example as means for deecting the beam, but it is clear that other means, for example, electromagnetic means, might be employed for this deection in one or more directions.

Tubes incorporating characteristics of the invention may be arranged to be employed as frequency multipliers giving to an output electrode, for example to the electrode 24 of Figs. 3 and 4, the form of a grid. Such operation may also be obtained by providing in the generating structure of the electronic beam an electrode acting as virtual source of electrons in the form of a grid. The two electrodes may, moreover, be simultaneously provided in the form of grids.

The devices incorporating characteristics of the invention can also be provided for the production of currents of predetermined shapes. For example, the tube of Figs. 3 and 4 may be adapted to produce crenellated currents, by applying to the deecting electrodes a relatively low alternating potential, while carrying out the tube with a very fine rectilinear filament and a suiciently wide slot with respect to the image of the lament in the electrode 24. The crenellated current obtained will be of'very pure form, even with a high fundamental frequency.

In another manner, in devices incorporating characteristics of the invention, currents of any predetermined form may be obtained by providing special shapes for the slot of the diaphragm playing the part of virtual source of the electronic beam, and for the opening of the rst output electrode. Thus for example, very pure sawtooth current waves may be obtained.

'I'he electronic beam servingas intermediary to the amplification with a view to various applications mentioned in the specification will be replaced by a beam of electrified particles of any sign, positive or negative ions, giving a suitable sign to the various potentials controlling the beam.

The arrangement of the electronic lenses is only given by way of example; it is possible to employ any kind of electronic lens, either electrostatic, electromagnetic, magnetic or a combination of these various systems.

It should be noted that in tubes incorporating characteristics of the invention the slope is not limited, even with a very low capacity between oscillating electrodes, on account of the possibility of obtaining by construction an electronoptical amplication of any necessary value.

Moreover, in carrying out the tube so that. it

has between the control and output structures the symmetry indicated with regard to the embodiment of Fig. 3, the absence of retroactive coupling permits the use of such tubes at very high frequencies, without the time of transit of the electrons between the cathode and the last output anode intervening as limitation to the use of such tubes. Moreover, the signal applied to the deflecting plates will only be distorted if the time of transit of the electrons between the deflecting plates is considerable with respect to the period; consequently the length of the deecting plates will be preferably taken relatively small, and their .4

average potential will be increased when it is desired to obtain a tube for extremely high frequencies, for example up to 2000 megacycles, The displacement of the image will then be very small, but the electronic lens placed in the tubes of the invention after the deflecting plates will then be provided so as to give the eect of an electronic microscope, strengthened in order to obtain on the output structure of the tube a displacement of satisfactory magnitude.

Although the invention has been described in the case of particular embodiments it is obvious that it is in no Way limited thereto, and on the contrary, is capable of numerous modifications and adaptations Without departing from its scope.

What is claimed is:

l. Electron beam apparatus comprising means for generating an electron beam, means for shaping said beam, means for receiving said beam, means for deflecting said beam positioned between said generating means and said receiving means, and means for amplifying the deflection given to said beam by said deflecting means positioned between said deflecting means and said receiving means comprising a converging electron lens focussed on said beam at a point between said deflecting means and said generating means, said deecting means comprising two semi-cylindrical electrodes, and said electron lens comprising a cylinder, said cylinder and said electrodes being coaxial.

2. Electron beam apparatus comprising means for generating an electron beam, means for shaping said beam, means for receiving said beam, means for deecting Vsaid beam positioned between said generating means and said receiving means, and means for amplifying the deflection given to said beam by said deflecting' means positioned between said deecting means and said receiving means comprising a converging electron lens focussed on said beam at a point. between said deiecting means and said generating means. said means for receiving said beam comprising at least one anode and a layer of secondary electron emissive material on said anode, the secondary emissive power of said material being different at diierent parts of said anode.

MARGUERITE CLEMENTINE ELISE PINGUET,

ROBERT EMILE PIETRE,

Legal Administrators of the Estate of Jean Bemamont, Deceased.

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