US2597571A

US2597571A - Cathode-ray wave generator

Info

Publication number: US2597571A
Application number: US29860A
Authority: US
Inventors: Carmen L Cuccia
Original assignee: RCA Corp
Current assignee: RCA Corp
Priority date: 1948-05-28
Filing date: 1948-05-28
Publication date: 1952-05-20
Anticipated expiration: 1969-05-20

Description

May 20, 1952 C. l.. CUCCIA cATHoDE-RAY WAVE GENERATOR Filed May 28, 1948 .5J Fly; fi: i ff L] iff" 11,5:

ZJ y

Il j] j# Z j? INVENTOR f4 Fg i5 f7 Patented May 20, 1952 cannone-RAY WAVE' GENERATOR Carmen-L. Cuccia Irinceiaix'n` 1N, J., assigner, tc'

Radio .L Corporation voiwiimerca', l.acorporation of Delaware:

Application Ml 428, 1948,` Serial No. 29,860v

This inventionrrelates to `multivikuators-and Wave generators, and moreM particularly 'to such devices for operation at very-highifrequencies.

t has been customoryinsuch'devicestoeme ploy tuned circuits `or time-constant"circuits to determine the operating fre'quencywhich; therefore, has an upper limit due tothe reactive components in such circuits.

The main objects of this inventionare toiexa tend the operating'limit to very-high frequencies and to simplify the circuits `of multivibratoi'sy as such, and as frequency controls 'for 'wavegenerators. Broadly, these Vobjects `'are laccomplished by using interele'ctro'de capacities forreactance in combination with `resistance in external'cire cuits, and electron beam dee'ctionfor"switching.

Another object is to vary .and'controT the frequency by simple adjustment of resistance:y

A related object is `to 'generate Yvvavescf desired shape at the multivibrator frequency'orya mul;- tiple thereof.

A further Objectis to'providea 'variableefrequency Wave generatoithat does notuse'tuned circuits.

Other objects and advantages of "th'e'zinvenation Will become apparent from. the"follwing description in connection with vtheaccompanying drawing in which: Fig. 1 illustrates a multivibrator'according'to the invention;

Fig. 2 illustrates a multivibrator-Wave-'gener'e ator according to the' invention; and

Figs. 3 to 7 show various anode arrangements that may be used in the generator ofFig'. 2.

In the several gures like yreference characters indicate corresponding parts.

Referring to Fig. 1 reference character vIt) represents an evacuated envelope for an electron tube in which are disposed an electron emissive cathode -ll partly surrounded by a shield -|2to which it may be electrically connectedandprovided With a lead I3 extending through the wall of the envelope. Adjacent the A open part of shield I2 are accelerating electrodes 15,116y provided with leads l1 `and VI8 .respectivelypftill further from'the cathode .lzl are "defiecting electrodes and 2l provided with leads 22 and 23 respectively. Reference characters -landv2-6- iiidicate anodes disposed so that a .beamfoffelecitrons from' the cathode vIl may strike either of V50 them. Leads 21 and 28 provide separate eX ternal connections for the anodes 25 land A shield 29 of mica or othersuitable material may be disposed between said `anod'es fifldesiredv-.ig

External circuits: interconnectingEikel?elec-f 2. trodes`-abcve described may-comprise a source 'of potential Vsuch as batteries 3l! and 3l connected in series, the negative terminal being connected to 'cathode lead I3. The positive terminalv of battery 3G isconnected to leads Il `and i8 for supplying-a relativelypositivepotential vto the electrodes -|5and 16; The positive terminalfof batteryi-Il is connectedwto

anodes

25 and 26 through separate circuits,` one of which `comprises` a load -32 in` series with an adjustable resistance' connected toV lead 21 andthence to anode L25.- The otherfY anode circuit comprises load 35 connected through adjustable resistance 35 to lead 28 and thence to anode 2S. Anradjustable tap 3'! on resistance 36 is connected,` to onerendof a-poten-tiometer 38, the other Vend of Whichis 'connectedtocathode lead I3.v The lead 23 :makes adjustable contact with potentiometer A38 'for adjusting the potential of electrode. 2|. Similarly, an adjustable tap 40 on resistance 33 is connected -to one end of .a Apotentiometer 4|, the other end ofwhich is connected to cathode lead-lfa 'contact on said potentiometer being connected to -lead- 22l --for adjusting the potential-ofelectrode129;`

'Ihjarrangementfet Fig.- A1 is a multivibrator which'operates as Ifollows. Cathode Il may be heated known-manner and electrons emitted thereby-are directed toward the anodes 25,` 26 by the shield 12"which1prevents electrons -from being 'emitted-'exceptfrom its open portion.- The positive potential applied Ato electrodes l5, I5 fromthe battery 30 accelerates the electronsand thefelectrostatic linesof force -thereby set up in theregion between said electrodes andlshield l2 concentrate thelelectrons in Aa. vbeam which, .in a balanced condition, projects `in vthe Adirection of ther-tube axis. The .beam-forming members may bencailed an lelectrostatic lens. .Thebeam normally.wouldbe...split5iby.the shieldZS and the electrons wouldzbe dividedbetween'the anodes 25 and'ZE. However, there is usually some unbaiance hwhich; for finstanceycauses most; or Vat least; a preponderance, ofthe electrons to strike vanode'tlvandthereby setup an anode current fronrthe batteresS, `lftlnough load 32, resistance A33, lead 2l, 'to anode 25, and thence to cathode Il. This anode current causes a potential drop `in resistance' 33 "which reducesv the potential of electrodef according to the position of tapm VInasrnuchras the anode '26 is receiving veryxfewor noI electrons, there Will be'very little or'rnozanode icurrent inresistance 35 and the 4potential loffcthefcorresponding .deflectingl elec- ,trodezfZl' will bewdetermined'prirnarily or .solely beam across the anode 45.

by the position of lead 23 on potentiometer 38. The potentiometer is so adjusted that the positive potential of electrode 2l is sufficient to deiiect the electron beam to the anode 25 without attracting the beam to itself. Hence, the reduction of the potential of deflecting electrode 25 as described above, permits the higher potential of electrode 2| to deiiect the beam from anode 25 to anode 25. The resulting anode current through resistance 36 reduces the potential on electrode 2l and at the same time the potential on electrode is restored to the value determined by the position of lead 22 on potentiometer 1li. This relatively higher potential on electrode 25 causes deflection of the beam back to anode 25. The beam is thus deflected alternately between

anodes

25 and 26 at a frequency which is determined by the circuit parameters, such as the interelectrode capacities and the adjustments of

external resistances

33 and 36 and potentiometers 38 and 4l. The oscillations thus set up by the multivibrator may be utilized in the

load circuits

32 and 35.

Referring to Fig. 2 a similar multivibrator is provided with an envelope l0, cathode Il, shield I2, deflecting electrodes 20 and 2|, anodes 25 and '26, and external circuits comprising a resistance for each anode and a potentiometer for each deiiecting electrode, as described in connection with Fig. 1. In the Fig. 2 arrangement the electrodes l5 and I6 and battery 30 have been omitted so that deflecting electrodes 20 and 2| also function as beam concentrating accelerating electrcdes.

A separate anode is provided in the arrange- `source of variable anode potential 48 and ammeter i9 which is connected to cathode lead i3. The output circuit just described utilizes oscillations generated by the sweep of the electron This sweeping Vor switching action is obtained by the multivibrator action of

anodes

25 and 26 and their associated electrodes and circuits as described in connection with Fig. l. The frequency of the oscilla- -tions thus generated is determined by the frequency of the multivibrator and the wave shape is determined by the conguration and `relative disposition of

anodes

25, 26, and 45.

Fig. 3 illustrates an arrangement in which a separate or additional anode 50 is disposed further from the cathode than the

anodes

25 and 26 and receives the beam of electrons through the space 5I between said anodes. This arrangement provides a sharp cutoif for the edges of the beam and is useful in generating square waves.

Fig. 4 shows another arrangement wherein an anode 52, having a relatively small cross-section perpendicular to the beam, is disposed closer to the cathode than the

anodes

25 and 26 and preferably is in alignment with the space 5l therebetween. If the anode 52 is made very narrow, such as in the form of a ne Wire or thin strip, the generator will produce an output wave consisting of sharp pulses, the Width of which is determined primarily by the width of the electron beam.

Fig. 5 illustrates another modification in which a number of small cross-section anodes 54 are disposed between the cathode and the

anodes

25 and 26. The anodes 54 preferably are spaced equa1 distances apart and connected to a common lead 55. The connections should be made at the extreme ends of said anodes so that lead sov 55 will not be struck by the electron beam and thereby act as an anode. In this arrangement a pulse is generated as the beam passes each of the anodes 54 and thus produces successive pulses having a frequency which is a multiple of the beam deflection frequency. Hence, with the anode arrangement of Fig. 5, the tube and circuit arrangement of Fig. 2 becomes a multivibratorfrequency multiplier.

Another anode arrangement is illustrated in Figs. 6 and 7, the former being an edge view and the latter being a perspective view. The anodes 57 and 58, which correspond in function to

anodes

25 and 25, have disposed therebetween an additional anode 60 which may have such configuration that it will produce a desired wave shape when the electron beam sweeps across it. The anodes 51 and 58 are cut out as shown at 6I and 62 toaccommodate the shape of anode G. As the electron beam sweeps from left to right it will first strike entirely on anode 58 and then the beam will be divided between anodes 56 and 60 according to their relative configurations. In the region 63 between anodes 51 and 58, the anode 65 will receive substantially all of the beam electrons and thereafter anode 5l will receive a greater and greater proportion thereof according to the relative configurations of anodes 60 and 5l. The process and wave shape are reversed when the beam sweeps from right to left.

The above arrangements provide both a multivibrator and a wave generator which latter may be also a frequency multiplier. Very high frequencies are obtainable with the arrangements disclosed due to the small reactance of the interelectrode capacities and the use of resistances in the external circuits. Obviously, the arrangements can be used for lower frequencies by providing inductance or lumped capacity in the external circuits.

The invention described above has general application to multivibrators and wave generators and, therefore, many changes may be made in the arrangements and modifications selected as examples for describing and illustrating the invention.

What is claimed is:

l. A wave generator comprising in combination an evacuated envelope, an electron gun mounted in one end of said envelope, said electron gun having a cathode and being adapted to project a continuous ribbon beam of electrons, a rst target and a second target mounted so as to intercept said beam of electrons, a first deflection plate and a second deflection plate mounted on either side of the neutral position of said beam, said deflection plates being adapted to deflect said beam along a line that is perpendicular to the plane of said ribbon beam, la source of potential having positive and negative terminals, a first resistance connected between said first target and said positive terminal, said first deflection plate being coupled to said resistor, a second resistor coupled between said second target and said positive terminal, said second deliection plate being coupled to said second resistor, a third target mounted between said first and second targets so that the electron beam strikes it as it moves back and forth l between the first and second targets, a load and a source of fixed potential connected in series between said third target and the cathode of said electron gun.

2. Wave generating apparatus comprising in combination an evacuated envelope, an electron gun having a cathode. and adapted to project a continuous flat beam of electrons, a first deection plate, a second deection plate, said plates being mounted on either side of said beam and so as to be parallel to the beam, a source of xed potential having positive and negative terminals, said negative terminal being coupled to said cathode, a first target and a second target, said targets being mounted so as to be capable o1' intercepting said beam of electrons at its extreme point of deection, a first resistor connected in series between the positive terminal of said source of xed potential and said rst target, asecond resistor connected between said positive terminal and said second target, a third resistor connected between said cathode and a point on said rst resistor, a fourth resistor connected between said cathode and a point on said third resistor, said first deflection plate being connected to a point on said third resistor and said second deection plate being connected to a point on said fourth resistor, a third target mounted between said rst and second targets, and a load impedance connected between said third target and said positive terminal.

3. Apparatus as described in claim 2 wherein said deection plates are adapted to focus the beam of electrons projected by said gun at said targets.

CARMEN L. CUCCIA.

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

UNITED STATES PATENTS Number Name Date Re. 20,506 Soller 1 Sept. 25, 1934 1,613,626 Van Der Bijl Jan. 11, 1927 2,011,920 Terry Aug. 20, 1935 2,096,653 Soller Oct. 19, 1937 2,165,308 Skellett July 11, 1939 2,190,069 Hollmann Feb. 13, 1940 2,239,407 Wagner Apr. 22, 1941 2,241,027 Bumstead May 6, 1941 2,247,350 Colberg July 1, 1941 2,256,301 Wagner Sept. 16, 1941 2,257,795 Gray Oct. 7, 1941 2,294,659 Herold Sept. 1, 1942 2,407,297 Skellett Sept. 10, 1946 2,475,644 Soller July 12, `1949