US2244260A

US2244260A - Electron discharge tube

Info

Publication number: US2244260A
Application number: US214945A
Authority: US
Inventors: Power Donnell Winship
Original assignee: RCA Corp
Current assignee: RCA Corp
Priority date: 1938-06-21
Filing date: 1938-06-21
Publication date: 1941-06-03
Anticipated expiration: 1958-06-03

Description

June 3, 1941: w, POWER 2,244,260 ELECTRON DISCHARGE TUBE Original Filed Aug. 18, 1937 4 .EW J

ir rr m 2/ our/ ar g ourkur INVENT OR I p. w. POWER ATTORNEY Patented June 3, 1941 UNHTE D STAT-ES 9 F ilCE 2,244,260 ELECTRON-DISCHARGETUBE Donnell Winshiplower, Summit, NQ L, assignor to Rad o Corporation of America, a corporation of Delaware Substitute'for abandoned application: Serial. No. 159,625, August 18j1937. This application June 21,.1938,SerialNo:214,945

5 Claims". (Cl. 250 162) This invention relates-in general to electron d1scharge tubes and more particularly *to -tub'e's utilizing an electron beam for high frequency generation or power amplification and is substitutedfor application Serial No; 159,625, filed Aug ust" It has been customary to -utilize.electrostatic beam deflection in electron tubes oi -the cathode ray type wherein an electrostatic fieldis' set up by potentials impressed ontwo or morepla'tes having substantially parallel surfacesz The el'ectron beam upon entering the field betweentwd such plates having electrical potentials impressed thereon, is acted upon by the field in such aman ner as to change the direction of travel of the beam in proportion to the potential differences of the two plates.

In cathode ray tubes utilizing-this method-of beam deflection it is necessary to concentrate the beam so that it will be uniformly acted upon by the electrostatic field between the plates. If the beam is not suficiently concentrated in 'a small cross-sectional area, various'sectionsof the beam may be deflected by varying amounts causing -a distortion of the beam as it passes between the deflecting plates. overcome by using plates of larger surface area so that the electrostatic field is as uniformas possible. The use of larger'plates, howeven re sults in greater difficulty in exhausting the tube;

and also adds to the cost of producing such tubes.

Another difficulty which is incumbent-upon the present system of. deflection is the necessityfforaccurate positioning of the deflection plates.

Each plate must be so located-asto lie "equidistant This effect may be'partially' from the normal position of the undefiected beamf and if the plates are not so locatedthe beam will be displaced and will produce a pattern'on'the anode screen which is notsymmetrical with the axis of the tube. A further disadvantage'of thistype deflection is the large voltage variationrequired for a given beam deflection These difii culties are, however, not attendant upon the tube" A further object of this invention is'to' provide deflecting means for an electron beam-which will operate to sufliciently defiect'the beam at a relatively low voltage.

will= become apparentito those skilled in the artfrom the following description ofthe device 1disclosedr It-is believed" that a complete understanding of ithe=invention maybe had by reference tothe following description taken in conjunction with the accompanying drawing,.in which:

Figure '1 shows the improved cathode ray tube and deflecting means; together: with its userin a simple amplifying or relayingcircuit.

Figure 2 shows a slightlymodified form of'the' tubeas used in alcircuit for-distortionless pushpull poweriampiification."

Figure '3 shows a still further form of tube andits application in a high frequency oscillator circuit.

Referring to Figure 1,it will beseen that the tube consists of an envelope i, which may bemade' I of glass, vitreousimateria'l, metal, etc. and fromwhich the air' has; been excluded. Within the sealed envelope is 'acathode or electron'emitter 2, which may beidirectlyor indirectly heated by any appropriate and well known means. Within the tube are also positioned accelerating; and

' focusing electrodes 3 and i. The purpose of these electrodes is to draw the electrons from-the emitter and to accelerate and focus-the stream of electrons into a beam.

In the other end of the tube is located a control normallylie in-the path of the undeflected electron beam Positionedalso in this end of the tube are two anodes 6 and l whichare in the i formof concentric rings or annulusmembers.

' These anodes are preferably constructed a of a metal low in secondary electron emission qualities such as nickel, and the surface of the anodes 6 and =1 may be supplied'with a layer of carbon or lamp? black-in order to further reduce the production of' secondary emissions caused by-the impact of the primary electron beam. In order to prevent whatever secondary electrons that may be omitted fromone of the anodes from reachingtheother, the edges of each of the anodes may be turrie'd'up, as shown in the drawing: These turned-up edgesalso perform the function of providing sharp cut-off of the beam current asdeflecting r0d5. This is particularly true if thepotential of the controlrod is slightly positive.

Other objects and purposes of this invention If; however, a negative potential is applied to the electrode orrode, which isso positioned as tocontrol rod, the electron beam is caused to diverge equally in all directions forming a cone. Such a deflection will cause the electron beam to strike the anode 6, and, if a further negative potential is applied to the control rod, the beam may be s-ufficiently deflected as to contact the anode 1.

In Figure 1 the accelerating electrodes are shown as perforated plates or discs but it is not necessary that these elements be made in this form. In Figure 2 the corresponding elements 3' and d are shown in the form of cylinders or tubes and function as accelerating and focusing electrodes in a manner well known in the art. In Figure 3 the second accelerating and focusing electrode l is shown as a conducting coating on the inside surface of the tube envelope.

Returning again to the disclosure Figure .1, the source of current I3 is shown for applying the proper voltages to the accelerating electrodes and to the anodes B and l. The input signal may be applied to the control rod through a transformer 8 and a variable condenser 9 is shown in the figure. A proper lbiasing potential is applied to the control rod through the use of the battery In. As the varying potentials are applied to the control rod the electron beam is caused to be deflected or spread in such a manner as to contact either the anode 6 or the anode 1. These anodes are connected to the output of the amplifier by way of the transformer H and the condenser [2.

It is obvious from the above discussion of Figure 1 that the presence of a signal variation on the control grid 5 will cause the same variation to appear at the output of the circuit in an amplified form.

In Figure 2 of the drawing a similar circuit is shown except for the manner in which the anodes 6 and 1 are connected in the circuit. In this circuit the anodes are connected to each side of the primary of the transformer I4, the mid-point of this winding being connected to the positive source of potential. Because of such a connection, a push-pull amplification of the input signal will result. The operation of the tube in this circuit is substantially the same as that described above in regard to the circuit shown in Figure 1.

In Figure 3 a circuit is shown for producing ultra high frequency oscillations. An advantage of this tube when used in this circuit lies in its inherently low time factor for deflection. It will be noticed that the electron stream emanating from the emitter is not interrupted or reversed during its travel to the anode plates, but is merely spread by the deflector rod as it flows from the cathode and focusing electrodes to the anodes. The efiect is thus a beam, the crosssectional area of which is varied between a maximum and a minimum value in accordance with the potential applied to the control electrode. The anodes in Figure 3 are connected to an oscillating circuit I5 to which is e1ectromagnetically coupled the control rod 5. The frequency of oscillation of the system may, of course, be controlled by varying the size of the condensers It or the coupling in a well known manner.

The operation of the tube in all of the above described figures is substantially the same. The electrons emitted from the cathode or emitter are concentrated and focused into a beam by the accelerating and focusing electrodes whereupon they continue and surround the control rod 5 and, depending upon the potential of the deflecting or control rod, the electrons will be directed to and impinge upon either anode 5 or 1. For example, depending upon the potential of the biasing battery H), the deflector electrode 5 in one instantaneous condition of the input circuit will not repel the electrons and they will proceed along element 5 to the anode 6. However, as the signal voltage is varied in the primary of the transformer 8 the deflector element 5 will become more negative and repel the electrons so that instead of falling upon anode 6 they are attracted to and impinge upon anode 1. Thus, if varying potential is applied to the control rod 5 a similar potential variation will occur in the output circuit of the tube except that it will be amplified by an amount equal to the amplification constant of the tube.

It is to be understood that any of the circuits shown and described or any of their modifications may be used with any of the tubes shown, and it is immaterial whether the accelerated electrodes are in the form of perforated discs as shown in Figure 1 or are in the form of cylinders as shown in Figures 2 and 3. Furthermore, it is obvious that other forms of accelerating electrodes might well be used.

It is also to be understood that it is not necessary that the anodes 6 and 1 be in the form of concentrically arranged rings, since other forms may of course be used, and furthermore, it is not necessary that only two of such elements be used since a larger number of anodes may be provided.

Various modifications may be made in the invention and it is to be understood that any and all such modifications shall be considered as falling within the purview of the disclosed invention except as limited by the following claims.

7 I claim as my invention:

1. An electron discharge tube comprising an envelope of vitreous material, means at one end of the tube adapted to produce a single focused electron beam of substantially circular crosssection, and a control rod mounted at the other end of the tube substantially coincident with the beam axis and adapted to be charged negatively with respect to the beam producing means to cause the beam to be dispersed conically with the cone apex being located substantially on the beam axis,

2. An electron discharge tube comprising an envelope of vitreous material, means at one end of the tube adapted to produce a single focused electron beam of substantially circular crosssection, and a rod-like control electrode positioned at the other end of the tube so as to coincide substantially with the beam axis and arranged in the normal path of the beam and adapted to be charged negatively with respect to the beam producing means to cause substantially uniform radial deflection relative to the beam axis.

3. An electron discharge tube comprising an envelope, means adapted to produce a single electron beam of substantially circular cross-' section of reduced diameter, comprising an electron emitter positioned at one end of the tube, electrode means adapted to accelerate and focus the beam, an annular anode positioned at the other end of the tube in a plane perpendicular to the developed beam and axially aligned therewith, and a rod-like control electrode centrally positioned with respect to the annular anode extending in a direction toward the emitter and adapted to be charged negatively with respect to the electron emitter to produce substantially radial deflection of the electrons of the beam.

4. An electron discharge tube comprising an envelope, means for producing a single electron Y beam of reduced cross-sectional area comprising an electron emitter positioned at one end of the tube, electrode means adapted to accelerate and focus the beam, a pair of annular anodes positioned at the other end of the tube in a plane perpendicular to the beam and axially aligned therewith, and a rod-like control electrode cen- 5. An electron discharge tube comprising an envelope, means for producing a single electron beam of substantially circular cross-section and of reduced diameter comprising an electron emitter positioned at one end of the tube, electrode means adapted to accelerate and focus the beam, a plurality of concentrically arranged annular anodes positioned at the other end of the tube in a plane normal to the beam and axially aligned therewith, and a control electrode positioned at the center of the anodes and extending in the direction of the emitter adapted to be charged negatively with respect to the emitter to cause the beam to be conically dispersed whereby the beam may be caused to impinge upon different anodes.

DONNELL WINSHIP POWER.