US2453647A - Electric discharge tube with deflection control - Google Patents

Description

Nov. 9 1948. A. J. M. VAN QVERBEEK 2,453,647

ELECTRIC DISCHARGE TUBEWITH DEFLE CTION CONTROL filed May 2, 1946 f If [I ATMRA/[x Patented Nov. 9 1948 UNITED STATES O F CE I a -2,45a6 f sLaoraicmsoHA G TUBE W g anemones contact Ad ianne, Johannes I w Marie ran beek, ,Eirrd hoyen, Netherlands, assignpr,

d trustee i,

s gjmnents, toHartford National Bank u liii ipany, Hartfotd," C n -J a Application has @1946, seem No. 2666,655 sInrtheNethei lands August 15, 194% inte t;

This invention relatesto an electric discharge tube in which an electron beams "controlled by deflection and in such 'a tube.

It is known in electric'dis'charge tubes comprising at least two anodes to group the electrons in beams and to transmit these beams by means of deflecting plates :to one of thetwo anodes in accordance with the voltage between the :de'flecting plates. Various kinds of such tubes are known, it being possible for a tube to be con structed iin such manner that the electrons traverse substantially straight paths from which they only deviate by reason of :the contro l vol tage of the deflecting ,platesandaccording to a further construction o'fthe discharge tube the electrons are so influenced by particular shapes and bias voltages of-the deflecting plate lfOf them will traverse curved paths'wi'thout depending on the control voltage of the deflecting plates. These electron paths are more or less curved by means of the control voltage of the deflecting plates so that, in consequence, the electrons will impinge on one or the other anode in accordance with the said control voltage.

Especially the latter construction is of very great advantage for tubes with double control in which the density of the electron beam is controlled by a control electrode which is nearer to the cathode than the deflecting control electrode since in such discharge tubes electrons which have arrived in the second control space are prevented by the tube construction itself from returning to the first control space so that these two spaces are well separated and the tube is thus adapted to perform two separate operations. One limitation of such tubes with deflection control is, however, that the gain and consequently the sensitivity is comparatively small.

Now, this difiiculty may be obviated by the use of an electron discharge tube according to the invention in which the electrons traversing curved paths are controlled by deflection by means of two or more deflecting members that have a curved surface whose hollow side is nearer to the flow of electrons. By means of this subdivision of the deflecting member into a plurality of parts of given shape it is possible to control the potential along the surface of the said member in such manner that greater sensitivity compared with the known constructions is obtained. Preferably, such voltages are applied that throughout the member a regularly varying potential is set up whose gradient varies along the surface of the deflecting members. The influence addition to a'e'ircuit includin agram 5;Gla/ims. (Cl. 250%1593 of the potential variations of "portions of the deflecting member aiccord-ing to the invention on the electron "paths will be set outmore 'ful'ly hereinafter-by referenceto the accompanying drawing and by a comarisen with the influence of is yar ied relatively 'tothe cathode or to the point from which the electron beam proceeds its insilence on the rays of electrons is similar to that of a displacement of the member parallel to itself. The influence of a' variation of the potenttal gradient along the deflecting member on the paths of electrons may be compared with that of a rotation of this member. It may be seenJirom the drawing that the control in the second manner results in a far greater deviation of the beam of electrons than in the first manner. Referring to Fig. 1 the curve I represents the electron path associated with a position of the deflecting member 131 which is designated by a full line. If the potential of the deflecting member rises its action corresponds to a displacement of the deflecting member to the positicn D11 shown in dotted lines and for this purpose the electrons will traverse a path according to the dotted curve II. The deviation from the electron'path at the point A is consequently through a distance a. Fig. 2 shows different electron paths III, IV and V for the case of the potential gradient along the deflecting member D being varied. If the position DIII of the deflecting member corresponds to the case of the potential along this member being constant, the lines DIV and UV will show the positions that correspond to potential difierences along the deflecting member, position DIV corresponding to the case of the left hand part of the member having a negative potential relatively to the right hand part, whereas this is reversed for position By. The variation of the electron paths for the various positions of the deflecting member are designated by the curves III, IV and V, It is obvious that the deflections b and c at the point A are substantially larger than the distance a of Fig. 1.

In a construction according to the invention the varying potential along the deflecting member is carried into practice in a simple manner. The simplest manner may be dividing the deflecting member of cylindrical shape by severing it along a straight line into two parts between which a control voltage is placed, Fig. 3 diagrammatically shows an arrangement in which this means is made use of. The electrons entering from the cathode K into the deflecting space are sent by variation of the varying potential that prevails along the deflecting member by means of the control voltage Vd either towards the anode A1 or towards the anode A2. It is obvious that this manner of deflection control may be used irrespective of the manner in which the electrons enter into the deflection control space.

The described simple manner of obtaining a variable potential gradient along the deflecting member may have the disadvantage that a sufficient gradual transition is not obtained. A much more uniform potential distribution is obtained, for example, if the severing line of the two parts has a shape curved or broken in a definite manner. It is advantageous, for example, to shape this line in zigzag fashion as shown in Fig. 4. This figure is a plan of a deflecting member which is divided into two parts I and 2 along a zigzagshaped line of demarcation. It is also possible to divide the deflecting member into more parts, it being also possible for the severinglines to have different shapes. In this case the parts may have fixed voltages relatively to eachother, for example by means of a potentiometer circuit as shown in Fig. 5. The controlling deflection voltage Va is placed across a potentiometer P to which parts of the deflecting member are connected at various points. The electrons proceeding from the cathode K are thus controlled so as to be able to reach either the anode A1 or the anode A2.

What I claim is:

1. An electric discharge tube comprising a cathode for generating an electron stream, a pair of anodes, a deflecting member for deflecting the electron stream to one or the other of the anodes according to the potential on said deflecting memher, said member comprising a plurality of spaced parts which jointly form'a curved surface whose concave side faces the path of the deflected e1ectron stream, and in which a describing line of the enveloping surface of the member forms a right angle with the direction of deflection.

, 2. An electric discharge tube as claimed in claim 1, wherein the line of demarcation of the various parts of the deflecting member has a curve or broken shape.

3. An electric discharge tube as claimed in claim 1, wherein the line of demarcation between two various parts of the deflecting member is zigzag-shaped.

REFERENCES CITED The following references are of record in the file of this patent:

' UNITED STATES PATENTS Number Name Date 2,161,466 Henneberg June 6, 1939 2,332,876 Uhlmann Oct. 26, 1943 FOREIGN PATENTS Number Country Date 115,986 Australia Oct. 22, 1942 851,534 France Jan. 10, 1940

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