US1986632A

US1986632A - Cathode ray tube oscillator

Info

Publication number: US1986632A
Application number: US418281A
Authority: US
Inventors: Clarence W Hansell
Original assignee: RCA Corp
Current assignee: RCA Corp
Priority date: 1930-01-03
Filing date: 1930-01-03
Publication date: 1935-01-01
Anticipated expiration: 1952-01-01
Also published as: DE613806C

Description

Patented Ja n. l, 1935 UNITED STATES "PATENT oral-or.

. S CATHODE RA! TUBE OSCILLATOR Clarence W. Hanseli, Port Jefferson,

signor to Radio Corporation of America, a corporation of Delaware Application January 3, 19:0, serm No. new

9 0lalms. (01. 260-313)- I My present invention relates to oscillators, and, more particularly, to oscillator circuits emmethod of, and means foreliminating tube noises in the final output of high frequency entube noises occur because of actual irregularities in the rate of emission ofv electrons from the tubecathodes; the method disclosed permitting greater radio frequency amplification to be used so that smaller values of radio frequency energy could. be amplified successfully, Briefly, my,

above mentioned patent discloses an amplifier circuit which comprises an electron discharge tube. including a cathode, a. plurality of anodes electrostaticallyshielded from the cathode, the anodes being connected in such a manner that variations in emission from the cathode result in equal and opposite variations in the anode output circuit whereby the disturbing anode currents balance out and no noise is presentin the output'of the amplifier.

vNow,.1[ have found that this novel cathode tube lends itself very satisfactorilyto operation in an oscillator circuit, so that it is not necessary to supply an additional type of tube to be used as an oscillator in equipment where an oscillator i in .a heterodyne or super-heterodyne type of radio receiver.

Accordingly, it is one of the main objects of the present invention to provide an oscillator circuit which permits the use of the novel form kinds of equipment, and the oscillation 'frequency of which circuit maybe controlled by. 4'6 piezo-electric means, a resonant long line, or an- 1 50 rendered stable with regard. to its oscillation frenquency, the frequency stabilizing means beingautomatic in its action. I 1 r o Other objects of the invention are to improve generally the efllciency of oscillation circuits em- 55 bodying cathode ray tubes, and to, further, pro

ergy'amplifiers, it being understood that such No. 1,850,104, supra,

is required as well as amplifiers, as, for example,

' of'cathode ray tube so that a minimum numj ber of types of tube may be employed in certain vide a tube which is durable and reliable in operation, possess a high power output, a minimum of undesired reaction between the electrodes of the anode circuit'and the electrodes of the input a frequency stable oscillatory circuit.

The novel features which I believe to be char acteristic of my invention are set forth in particularity in the appended claims. The invention itself, hbwever, as to both itsorganization' and methodof operation will best be understood by reference to the following description taken in connection with the drawing in which I have indicated diagrammatically several circuit organizations whereby my invention may be carried into effect.

In the drawing, I 7

Fig. 1 diagrammatically shows an oscillatory circuit embodying the invention.

Fig. 2 shows an oscillation circuit employing an a modified form of frequency stabilizer.

Referring now to the accompanying drawing in which like reference characters indicate the same parts in the different figures there is shown in circuit, andwhich may be readily arranged in 6 Fig. 1, a cathode ray tube ofthesame construction'as disclosed in' my aforementioned Patent wherein the tube is I de-- scribed ingreat detail. Accordingly, I will, in this application, confine myself to essentials n essary only for a clear understanding of the presso ent employment of the tube. The tube cathode 1 is heated by a source A, the resulting electron stream 20 therefrom, passing between a pair of elongated electrodes 13. 13'. I

A pair of anodes 9, 9' .aredisposed within the :6 tube, and electrostatically shielded from the cathode and control electrodes by a screen grid electrode 10. The latter is supported by a metal- .lic, cylindrical envelope 11, the envelopebeing ailixed to a metallic disk-like support and shield 14.- The anodes are energized from a source 28, p v the positive terminal of the latter being connected to the anode circuit, the latter including the I inductance 20' and the variable capacity 21 shunted across the lattenwhich circuit connects thej'anodes in push-pull fashion.

A second metallic, cylindrical envelope 32 8111':-

rounds the

control electrodes

13, 13'. and is negatively biased by means of a lead 18 from the source D, the function of the envelope being to concentrate the electronic stream 20 issuing from tlie cathode 1. \T h screen grid 10 is positively biased through a lead 19 and me'mber 14, from.

a source it. .The control electrodes 13' and 13 an connected in series through an inductance 31,

' connected to any useful load may be coupled to v line type of frequency control is as follows: The

2 the midpoint of the latter being tapped and connected through a lead 32 to the negative terminal of source C, it being noted that the sources D, C, E, and B are connected and grounded between the positive terminal of source and the negative terminal of source E.

m order to feed back energy from the output circuit to the input circuit the inductance 20' is coupled to the inductance 31. Itwill, be noted that this inductive coupling will be the only source of feedback; inasmuch as there is no possibility of feedback occurring within the tube due to the electrostatic shield 10. By varying the condenser 21, it is of course, possible to vary the oscillation frequency of the circuit. A coil 40,

the inductance 20' for utilizing the'oscillations set up in the anode circuit of the tube.

The tube, arranged as shown inFig. 1, constitutes an initial source of oscillations. To stabilize its frequency piezo-electric crystal means, generally designated as 41, may be connected in the input circuit, in shunt with the inductance 31. The stabilizing action of the crystalis well known to those skilled in the art.

Again, the long line type of frequency control employing a resonant line may be employed. This'type of control is shown and-claimed in my application Serial No. 400,489 gfiled October 18, 1929, now Patent No. 1,945,546 granted February 6, 1934. I have therefore shown the resonant long line type of frequency control in Fig. 1, in diagrammatical manner, as comprising a pair of

electrical conductors

50, 51 each of which has one end connected to one side of the inductance 31. A shunting conductor 52, adjustable in the direction of the arrow, is adapted to vary the physical length of the two conductors. A capac ity 53 should preferably be shunted across the inductance 31 for rendering the input circuit more readily susceptible to resonance, phenomena.

- While the crystal control will ordinarily be employed independently of the resonant line control, they may be employed in combination, if desired. Briefly, the operation of the resonant long long,

resonant line

59, 51, 52 acts as a sharply tuned circuit having substantially uniformly distributed inductance and capacity. Standing waves are built up on the line giving it .an equivalent input reactance which is dependent solely upon the frequency, the length of the line, and independent of any reaction caused by external circuits or loads. These standing waves producedon the line,

an; applied to the oscillating tube .for controlling t nant circuit to pull the oscillator into step therewith.

Again, the line may be considered to act 'as a phase shifter, .waves from the oscillator being sent over to the line to the farend and reflected back to the oscillator, arriving back with a phase which shifts rapidly with changev of frequency and which tends to modify the oscillator frequencyto make zero difference in phase between theingoing and reflected waves at the input end of the line. That is to say, the long line acts to pull the oscillator into phasewith its own as ciliations whenever there is a shift in phase caused-bye. shift in the oscillator frequency.

- The output from the anodes 9, 9' being connected, as shown, in push-pull manner, it therefore results that the equal variations in theisaheated by source C.

I e frequency of the latter. Thus, the long line acts as a very sharply tuned reso- Y occurring at

points

54, 55 will appear on the conode currents due to the usual source of tube noise will balance out, and no noise will be transmitted with the useful'signals. 1

InFig. 2, I have shown an oscillatory circuit employing a cathode ray tube, as in Fig. 1, the circuit being modified, however, for frequency control by a long line of the. aperiodic, impedance matched type. The latter type of' control has been described, in detail, andfclaimed by J. L. Finch and J. W. Conklin'in application Serial No. 363.660 filed on May 16, 1929.

In adapting this type of long line control to the present cathode ray tube oscillation circuit, the'input and output circuits are tuned by the

variable capacities

53 and 21 respectively.

As in Fig. 1, the anodes 9, 9' are connected in push-pullto the source B. The, cathode is negative terminal of source C is connected through a resistance R, to the midpoint of the inductance 31, the the control electrodes'13, 13'. The resistance R is shunted by a radio frequency by-pass capacity 60. A pair of series connected

capacities

61, 62 are connected across the cathode and their midpoint grounded for by-passing radio frequencycurrents to ground so-that no radio frequency voltage will appear onthe cathode. I

The source D negatively biases the envelope 22, the positive terminal of the source D being connected to ground, the positive terminal of the source C, and the negative terminal of source E also being grounded. The inductance 31 leadjustably tapped by two electric conductors .50, 51, as at 50', 51, on either side of the midpoint connection. The opposite terminals are con-' nected to the anode inductance 20', as at 54, 55, through capacities 56 and '7, on either side of the source 3 midpoint connection.

Briefly, the operation of this type of control is latter being .in series withthe latter also serving to negatively bias both control electrodes. The

as follows: For the production of sustained oscillations by means of the cathode ray tube it will be necessary that the control electrodes 13 and 13' and anodes 9 and 9' fluctuate in potential 180 degrees out of phase for a desired tionship for the production of stable sustained oscillations, a long lineis connected from the points 54 and frequency. In order to cause this phase rela- 55in the output circuit of the tube to points and 51" in the input circuit thereof.

. By making the long line an odd number of half wave lengthslong at a desired frequency,

or by making it an even numberof half wave lengths long and reversing the connections at I one end, it will be seen that potential variations trol electrodes 13, 13' a certain period of time later, because of the time required to travel over the

lines

50, 51 so as to be opposite in phase to potntial fluctuations, occurring at

points

54, 55. For any other frequency of

potential fluctuationsthe lines

50, 51 will not be of the coriect.

amplified to any desired extent bythe suitable choice of the values for the electrical elements involved so that either regenerative amplification or sustained oscillations results. The anode output of the tube may potential is kept from the control electrodes by means of the blocking condensers 56, 57. The

taken from an inductance 40 which is inductively coupled to the output inductance 20', the coil it) being connected to any utilizing circuit. In order to prevent reflection, the line and 51 are tapped on in-. ductance 31 at points which cause the llnes'to be terminated by an impedance R, in the form of a resistance, corresponding in value to the surge, or characteristic impedance of the lines The exact frequency'for which the circuit oscillates readily and with maximum efilciency and stability is obtained is adjusted by varying the lengths of the

line

51, 50. While I have indicated and described several systems for carrying my invention into eflect, it will be apparent to one skilled in the art that my invention is by no means limited to the particular organizations as well as in the apparatus employed, may be made without departing from the scope of my,

invention as set forth in the appended claims. In .particular I wish to point out that the detail .proportions and construction of the cathode ray shown will undoubtand an output circuit'connected to said anodes,

both circuits being tuned oscillations,

to the frequency of the means for regeneratively coupling the input and output circuits together externallyand a plurality of anodes,

. the input of said tube, means for preventing feed-back inside said tube, and means for stabilizing the frequency of the oscillati'om by coupling to the input circuit only of the oscillator a piezo- 2. An apparatus for producing electrical oscillations comprising a cathode ray type of vacuum tube having a plurality of control electrodes means for-suitably applying direct current potentials to the control electrodes and anodes ofthe tube, input and output circuits each tuned to the frequency of the oscillations,

and output circuits. and means independent, of said output circuit comprising a sharply tuned resonant transmission line circuit'on which stationary electromagnetic waves are allowed to develop coupled to the input circuit of said oscillator for stabilizing the frequency of the oscillations, and a utilization circuit coupled tosaidoutput circuit.

3. n a paratus for producing electricaloscillations comprising a cathode ray type of vacuum tube having a cathode, a plurality of control. electrodes, and a plurality of anodes,

- means for applying a negative potential to said control electrodes and a positive potential to said anodes with respectto the cathode of said tube, input and output circuits tuned to the fre uency of the oscillations connected to said control electrodes and said anodes, respectively, and means comprising a transmission line on -shown and described, but that many modifications in the circuitiarrangementa'.

means for regeneratively coupling which standing waves are developed for regen-' eratively couplingthe output and input circuits together whereby the frequency of the oscillations is held substantially constant.

4. In oscillation generating apparatus, a 5

cathode ray electron discharge device having among the electrodes contained within its evacuated container an electron emitting cathode, a plurality of control electrodes and a plurality of anodes, an input circuit connected to the control electrodes and an output circuit connected to said anodes, said output circuit being tuned to the regeneratively coupling the input and output circuits together, an electromechanical vibrator and a resonant transmission line coupled to the input circuit of said device for stabilizing the frequency of oscillations, said vibrator acting to overcome small variations in frequency and said resonant transmission linelactingto overcome greater variations in frequency.

5. In oscillation generating apparatus, a cathode ray electron discharge device having within an evacuated container an electron emit- -tingcathode, a plurality of control electrodes frequency of the oscillations, means for and a plurality of anodes, an input circuit forsaid control electrodes and an output circuit for said anodes, said output circuit being tuned to the frequency of oscillations, means comprising a long transmission line long relative to the wave length of the working frequency for' regeneratively coupling said input and output circuits together and for controlling the frequency of oscillations appearing in said input circuit.

6. In an oscillation generator,-a cathode ray electron discharge .device having within an evacuated container a plurality of anodes, a plurality of control electrodes, and an electron emitting cathode, external; means for coupling said anodes and control electrodes together,

means for preventing internal feed-back in said device, a crystal in circuit with the control electrodes of said device, and a tunable resonant circuit connected to the anodes of said device.

. 7. In an oscillation generator, a cathode ray electron, discharge device having within an evacuated container aplurality of anodes, a plurality of control electrodes, an electron emitting cathode, a tunable input circuit connected to. said control electrodes, and a tunable output circuit connected to said anodes, and atransmission line long relative to the working wave length coupling said input and output circuits of said device for controlling the frequency of operation thereof. 1

8. In apparatus for producing electrical oscillations comprising a cathode my type of vacuum tube having a cathode, a plurality of control electrodes, and a plurality of anodes, means for suitabh applying a negative potential to said control electrodesand a positive potential to said anodes of the tube with respect tosaid cathode, tunable input and output circuits connected to said control electrodes and anodes, respectively, and means comprising a transmission line aunultiple of a half wave length long.

on which standing waves are generated for regeneratively coupling the output and input circuits together whereby the frequency of the oscillations is held substantially constant.

9. An apparatus for producing electrical oscillations comprising" a cathode ray type of vacuum tube having a plurality of control electrodes and a plurality of anodes,

means for suitably ap-' plying a negative potential on said control electrods and a positive potential on said anodes of the tube with respect to,the cathode, means to concentrate the electron stream emanating from the cathode, input and output circuits each 5 tuned to thefrequency of the oscillations, means for regeneratively coupling the input and output circuits, and means independent of said output circuit comprising a sharply tuned resonant transmission line circuit on which stationary waves are allowed, to develop coupled to the 4 input of said oscillator for stabilizing the frequency of the oscillations, and a utilization circuit coupled to said output circuit. CLARENCE W. HANSELL.