US2106172A - Vacuum tube - Google Patents

Description

Jan. 25, 1938. HAFFCKE 2,106,172

VACUUM TUBE Filed July 30, 1936 4 Sheets-Sheet l INVENTOR PHILIP M. HAFFCKE ATTORNEY Jan. 25, 1938. R M HAFFCKE 2,106,172

VAQUUM TUBE Filed July 30, 1936 4Sheets-Sheet 2 INVENTOR PHILIP M. HAFFGKE P. M. HAFFCKE 2,106,172

VACUUM TUBE Jan; 25, 1938.

Filed July 30, 1936 4 Sheets-Sheet 3 INVENTOR PHILIP M. HAFFOKE 5 as v ATTORNEY Jan. 25, 1938. p M HAFg-CK 2,106,172-

VACUUM TUBE Filed Jilly 30, 1936 4 Sheets-Sheet 4 INVENTOR PHILIP M. vHAFFCKE ATTORNEY Patented Jan. 25 193 8 UNITED s'rzrrlars PATENT OFFlCE 27 Claims.

(Granted under the act of March 3, 1883, as

amended April 30, 1928; 370 0. G. 757) I ,the electron stream within it to reduce the output of energy to a..predetermined value;

To provide a tube that may be so operated that the output thereof will be reduced substantially to zero automatically when energy of excessive amplitudes is impressed thereon;

To provide a tube that will, under certain conditions of operation, generate harmonics that will be eliminated in the following tuned circuits for the duration of excessive amplitudes of received energy;

To provide in a vacuum tube means to absorb energy from the electron stream in the tube, which absorption is a function of the amplitude of the energy impressed upon the tube;

To provide a method of and means for automatically eliminating from a radio receiving system the effects of static.

In the drawings: i

Fig. 1 is a side view, with parts broken away, of the electrode assembly of a tube according to my present invention;

Fig. la is an end elevation thereof;-

Flg. 2' is a schematic diagram of a circuit that includes a tube having the electrode arrangement shown in Fig.' 1;

Fig. 3 is a schematic diagram of a circuit having in' it a tube like that in Fig. 1 modified by the addition of an electrostatic shielding electrode:

Figs. 4 and 4a are respectively a partially broken side view-and an end elevation of the modified tube used in the circuit of Fig. 3;

Figs. 5 to 8 illustrate various circuit arrangements for utilizing thenovel characteristics of my new tube.

The standard types of vacuum tubes are so constructed and operated that the major portion of the current flowing through the cathode is that of the anode or output circuit, whereas under the practice of the present invention the tube is so designed and connected in the circuit that the major portion of the current through the cathode is, under certain conditions, automatically derived from elements other than the anode for the duration of those conditions. As disclosed in Figs. 1 and 1a, the signal input grid or control grid 9 is placed close to the cathode or electron emissive body In to exercise a high controlling factor upon the stream of electrons emitted from the cathode. Disposed between control grid Band plate H, is a foraminous metallic interceptor gri'd. l2, which may be of mesh or other construction, and a second like interceptor grid 13 is interposed'between interceptor grid l2 and plate I I. As will hereinafter appear, the ffunction of grids l2 and I3 is to intercept electrons from the electron stream to prevent their reaching plate ll,'and the term interceptor is therefore applied to distinguish them from the control grid, electro static shielding grid and suppressor grid of the prior art.

Fig. 2 shows a tube and. associated network incorporating my present invention. The inductive coupling I4 is connected to control grid ii of tube It having the usual cathode l1 and anode l8 with interceptor grids l2 and I3 interposed between control l5 and plate l8. Interceptor grids l2 and I3 are connected through series resistances l9 and 20 to the same positive potential as is platesupply lead 2|, these resistances having values of from 100,000 ohms up to several me'gohms, depending upon the use to which the tube I6 is put and the critical working limits desired.

The positive bias on grid l2 will attract electrons of the stream in the tube and-a portion'ot them will be intercepted and absorbed while the remainder will pass through the mesh of the grid. Those that pass will be attracted by grid l3, where again a portion will be intercepted and those that pass through will reach the anode to furnish the output current. In the space between grids I2 and I3 there will be two forces acting upon the electrons-an accelerating force due to grid l3 and anode I8 and a decelerating force due to grid 12. The acceleration will ordinarily predominate but the deceleration will aid in the interception of electrons by grid l3 by detracting from the forces tending to move them to the plate. The same condition will obtain betweeen grid l3 and anode l8, and will tend to prevent secondary emission. The electrons intercepted by grids i 2 and 'l 3 will set up currrents through these grids and the cathode l1 and the potential drop due to these currents traversing resistances I9 and 20 will reduce by so much the tion of electrons. It is apparent that there will arise-a condition of equilibrium whereby the output of tube IE will substantially follow the fluctuations of control grid l5 so long as the ampli-' .tudes are within the normal working range.

However, as the voltage of grid l5 swings positive above the. critical value the depression of .the potentials on interceptor-grids l2 and I3, by

the flow of the increased currents through resistors l9 and 20, will cause the plate output to reach saturation quickly and the curve of plate current will level off and undergo no further increase of noteworthy magnitude even though the grid I5 is swung strongly positive, so that the Er-Ip curve is very flat over aewide range. Moreover, by proper choice of resistor and voltage valuesthis curve may be made to return to zero for strong positive swings of grid I 5 due to static surges above normal amplitude, thereby substantially completely interrupting the output current. The resistances l9 and 20 are preferably of values comparable to the impedance in tube I 6 between therespective grids l2 and IS on the one hand and cathode l1 on the other, at no signal. Condensers should not be used in the circuits of the interceptor grids in order that the exterior circuits may be as nearly as possible replicas of those inside the tube and to avoid the introduction of time constants.

A receiving system that includes a stage using one of my novel tubes as above described 'gives very definitely improved performance over sets not having such a tube. For example, it has been used in the second detector position of a code receiver and gave a high percentage of readable copy from weak, distant stations, whereas a duplicate set having a standard screen grid tube in the second detector position was so blanketed by atmospherics that the signals were barely audible and the received signals were hopelessly unreadable by the operator. Tube IS in the second detector position was followed by an audio tone filter to remove the harmonics gen erated thereby.

Where the internal capacity between plate I! and interceptor grid I3 is detrimental, the modifled tube ii of Fig. 3 having an electrostatic shielding grid 22 is used. When this tube is in the radio frequency stages, grid 22 is grounded through bypass condenser 23.

Fig. 5 illustrates my novel tube serving as an output limiting device in a radio frequency stage. The grid I3 is grounded through condenser 24 and has the function of an electrostatic shielding grid. When so connected, grid l2 tends to offer a partial counterphase action in relation to the excitation from the input on control grid l5, when the input swing exceeds the critical value, and the change in the voltage on interceptor grid l2 resulting from the iiow of current through resistor l9 compensates to a large degree for the change in potential on grid Is. This has a tendency to hold the response within fairly close Tube l6 may be employed as a delayed volume control, one method of which is shown in Fig. 6. The time values are determinedby resistor t8 and condenser 25 and may be made of the order of 0.01 second if it precedes a static suppressing stage in broadcast reception. This will hold a program at substantially a constant amplitude and will aid vthe followingstatic suppressing" 2,106,172 resultant voltage on the grids and thereby (11 stage to operate most efiiciently, the time constant being longer than the duration of the average crash of heavy static. As in Fig. 5, bias on the signal grid l5 may be used, but excellent results are also obtained on moderate to strong signals when a resistor 26 is connected between input l4 and grid IS. The resistor 26 shows a definite drop of voltage when excessive surges'arrive and the grid current values are held down on the positive half of the cycle when the tube will rectify and pass considerable current in the grid input circuit. However, for most cases resistor 26 is not required as the impedance of the tube is much lowered during rectification and tends to load the input source heavily, a condition not detrimental to code reception, especially when the rectification does'not occur while the grid is op erating on the steep part of the Eg-Ip curve. Distortion in the output of the stage is harmonics, which are eliminated in the following tuned circuits. The condenser 21 is of relatively large capacity.

My novel tube' may be successfully operated without applied plate voltage, the signal being induced upon the plate by the electrons that approach it with suflicient velocity to strike the plate and impart their charges thereto, and the energy thus transferred may be utilized for special purposes, such as high fidelity receivers.

, A network so operating is shown in Fig. 7, the plate [8 being left floating without applied D. C. potential and the condenser 28 acting as a coupling between plate l8 and the following transformer primary 29. The momentum acquired by the electrons in the potential zones set up by grids l2 and I3 is suflicient to carry to the plate l8 those electrons that pass through both of the interceptor grids. In some cases, it is found advantageous to connect the radio frequency choke 39 between the plate I8 and ground, or a leak resistor 34 may be so connected as an alternative to using the choke 3|.

Where direct connection to the grid of a following tube is used in high fidelity amplifiers, it is desirable to connect a leak resistor 32 to the lead between plate l8 and the following tube 33, as

shown in Fig. 8. In this case the interceptor grids l2 and I 3 are excited from a source of constant high potential without series resistors to give adequate acceleration to, the electrons in order to progressively increase their velocity and efiect a greater transfer of energy to plate 18. The resistor 32, which may be several megohms, prevents blocking of the tube,. and may be replaced by either a tuned or an untuned impedanoe for special purposes.

In general, the higher the value of resistors l9 and 20, the lower the critical value of the input voltage swing that is required to cause the transconductance of the tube to fall to zero. Also, the lower the applied plate voltage, the closer the operating limits of signal input swing.

It is apparent from the foregoing that I have devised a vacuum tube whereby voltages may be applied to act upon the electron stream in a plurality of zones between the control grid and the output electrode which aifords effective automaticcontrol over the energy transmitted by the tube to prevent undesirable eifects of static surges tied to correspond, and used in a transmitter to avoid overloading the following input circuits.

The invention described herein may be manufacturedand used by or for the Government of the United States of America for governmental purposes withoutthe payment of any royalties thereon or. therefor.

I claim:

.. 1. A method of operating a vacuum tube, comprising applying a signal voltage to control an electron stream in said tube, intercepting from said stream at each of a plurality of spaced zones a portion of the electrons to set up a current through each zone separate from the current in the output signal channel, and utilizing the said currents to efiect a decrease of potential in the respective-zones, whereby increase of electron flow due to increase of signal voltage results, in

increase in said currents and greater decrease of potential in each said zone and a corresponding decrease in the proportion of the total stream passing all of said zones.

2. A method oi operating a vacuum tube, comprising applying a signal voltage to control an electron stream in said tube, intercepting from said stream at each of a plurality of spaced zones a portion of. the electrons to set up a current through each zone separate from the current in the output signal channel, and utilizing the said currents to effect a decreaseof potential in the respective zones, whereby increase of electron flow due to increase of signalvoltage results in increase in said currents and greater decrease of potential in each said zone and a corresponding decrease in the proportion of the total electron stream passing all of said zones until such condition is reached that increase in the signal voltage does not augment the stream passing all of said zones.

3. A method of operating a vacuum tube, comprising applying a signal voltage to control an electron stream in said tube, intercepting from .said stream at each of a plurality of spaced zones a portion of the electrons to set up a current through each zone separate from the current in the output signal channel and utilizing the said currents to efiect such decrease of potential in the respective zones that flow of electrons bethe electron stream, passes through elements in' said tube other than said anode'when the input yond' said zones is prevented when said signal voltage is above a predetermined value.

4. A method of operating a vacuumtub'e hav-- ing a cathode, an anode, a control grid, and a plurality of other electrode elements, which comprises so-adjusting exterior circuit values aflecting said tube that at least a major portion of the current through the cathode, deriving from signal voltage is of greater-than a predetermined value.

5. A method of operating a vacuum tube hav ing at least one electrode element in addition to a cathode, an anode and a control grid, which comprises so adjusting exterior circuit values affecting said tube that at least a considerable portion of the current through the cathode, deriving from the electron stream, is diverted from the circuit that includes said anodewhenj the input signal value exceeds a predetermined value.

6. A method-of operating a vacuum tube having at least one electrode element in addition to a cathode, an anode and a control grid, which cornprises so adjusting exterior circuit .values affecting said tube that all of the current through the cathode, deriving from the electron stream,,

is diverted from the circuit that includes said anode when the input signal value exceeds a predetermined value.

7. An electron tube network, comprising a vacuum tube having a cathode, a control grid, an

anode, and a plurality of mesh interceptor electrodes between said grid'and said anode, an output circuit includingsaid cathode and said anode, and means including an impedance connected. to each of said interceptor electrodes to connect said interceptor electrodes into respective circuits with said cathode in parallel with said output circuit, said impedance and'said anode being connected to a positive biasing potential.

8. An electron tube network, comprising a vacuum tube having a cathode, a control grid, an anode, and a plurality of interceptor electrodes between said grid and said anode, an output circuit including said cathode and said anode, and means including an impedance connected to each of said interceptor electrodes to connect said interceptor electrodes into respective circuits with said cathode in parallel with saidoutput circuit,

said impedance and said anode being connected to a positive biasing potential. V I

9. An electron tube network, comprising a vacuum tube having a cathode, a control grid, an

anode, and a plurality of interceptor electrodes uum tube having a cathode, a control grid, an.

anode, and a plurality of interceptor electrodes between said grid and said anode, anoutput circuit including said cathode and saidanode, means including an impedance comparable to the internal impedance of the tube at no signalconnected toeach of said-interceptor electrodes to connect said interceptor electrodes into re--- spective circuits with said cathode in parallel with said output circuit, said impedance andsaid anode being connected to a positive biasing potential,

and an electrostatic shielding grid between said interceptor electrodes and said anode, said shielding grid having impressed thereon a constant'potential;

, '11. An electron tube network, comprising a vacuum tube having a cathode, a control grid, an

anode, and a. plurality of interceptor electrodes between said grid and said anode, an output circuit. including said cathode and said anode,

including an impedance comparable to the internal impedance of the tube at no signal coiibectedto each of said interceptor electrodes t6 connect said interceptor'electrodes into respective circuits with said cathode in parallel with said output circuit, said impedance and said anode being connected to a positive biasing potential-,an electrostatic shielding grid between saidiinter'ceptor electrodes and said'anode, said shielding grid having impressed thereon a constant potential, and a condenser connecting said shielding grid to ground.

l2.-.An electron tube network, comprising an I electron tube havinga cathode, a grid ,'an anode,

an interceptor ,electrode', and. an electrostatic shielding-grid; an input circuit including said grid, said cathode, and means to limit the eflect upon said grid of a positive swing of energy in said input circuit, an impedance in series with said interceptor electrode, a condenser connected to said cathode and to a point between said interceptor electrode and'said impedance, and a condenser connecting said shielding grid to ground; said electrode, said shielding grid, and said anodehaving positive potentials impressed thereon.

. '13. A method of operating a high vacuum electron discharge tube having a cathode, an anode, and a control grid between said cathode and said anode, which comprises applying accelerating forces in a plurality of zones between said grid and said anode to the electrons emitted by said cathode, the transfer of electrons to said anode being effected solely! bythe velocity of emission and the velocity imparted by said for 14. A method of operating anelectron discharge device, which comprises controlling the electron stream therein by a signal input, and absorbing in a plurality of zones between the zone of said signal control and the output of ,the .tube a considerable portion of the electrons in .said stream, and applying in channels in parallel with the signal output channel, the currents derived from the absorbed electrons to effect further control of the electron stream.

15.A method of operating an electron discharge'device, which comprises controlling the electron stream therein by a signal input, and absorbing in at least one zone between the zone of said signal control and the output of the tube a considerable portion of the electrons'in said stream, and applying in channel in parallel with the signal output channel, the currents derived from the absorbed electrons to effect further control of the electron stream.

16. Amethod of operating an electron discharge device, which comprises controlling the electron stream therein bya signal input, and

absorbing in at least one zone between the zone .of said signal control and the output of the tube a considerable portion of the electrons in said stream, and applying the currents derived from the absorbed electrons to effect further control of the electron stream to reduce the output of the tube substantially to zero betweenage being a function of the number of electrons absorbed and the impedance offered to the flow of said electrons.

18. A method of operating an electron discharge tube, which comprises subjecting the signal controlled electron stream therein to combined accelerating and decelerating action in a plurality of zones between the zone of said signal control and the ouput of the tube with concomitant variable absorption of significant portions of the said stream in each of said plurality of .zones, within predetermined limits of said signal control,said variable absorption and said acceleration and deceleration being functions of the respective currents through said zones due to the absorption and to the impedances through which said currents respectively pass, the currents due to such absorption being kept out of the signal output channel.

19. A vacuum tube comprising an envelope, a

heated emitter, a grid having a controlling factor upon the electron stream, a signal output anode having higher internal impedance to the emitter than does any other electrode therein, and at least one electrode between said grid and said anode having a high' factor of absorption for electrons approaching the same, the currents due to such absorption being kept out of the signal output channel. I

20. A vacuum tube comprising an envelope, a heated emitter, a grid having a controlling factor upon the electron stream, an output anode having. higher internal impedance to the emitter.

than does any other electrode therein, a first electrode between said grid and said anode having a high factor of absorption for electrons approaching it, and a second electrode between said first electrode, and said anode likewise having a high factor of absorption for electronsapproaching it, the said electrodes mutually counteracting to a degree the action of each other upon the electron stream, the currents through said electrodes being kept out of the signal output channel. I 21. Amethodof operatinga vacuum tube. hav

ing an emitter of electrons and an anode which comprises accelerating in a plurality ofzones in said tube the electrons of the'electron stream, and the potential on said anode being derived solely from the electron stream.

22. A method of operating a vacuum tube having an emitter of electrons and an anode which comprises accelerating in a plurality of zonesin said tube the electrons of the electron stream, the electrons being carried to said anode solely by the momentum derived from said accelerating forces.

23. A method of operating a vacuum tube hav-. ing an emitterv of electrons, 'a control electrode and an anode, which comprises acting upon the electrons by drifting potentials in a plurality of zones between the control electrode and the anode, whereby the effect of the potential on the control grid and the effect of said drifting po-' tentials are complementary when said signal control potential exceeds a predetermined value.

24. A method of operating a high vacuum electron discharge tube having a cathode, an anode, and a control grid between said cathode and said anode, which comprises app y automatically variable accelerating forces in a plurality of zones between said grid and said anode to the electrons emitted by said cathode, the transfer of electrons to said anode being effected solely by the velocity of emission and the velocity imparted by said forces.

25. A method of operating a high vacuum elecanode, and a control grid between said cathode and said anode, which comprises applying ac 27. An electron tube network constituting a delayed volume control, comprising a tube having a cathode, a controlgrid, a first electrode, provided with spaces through which electrons may pass, a second electrode likewise provided with spaces, and an anode, in the order named, a resistive impedance connected in series' with said control grid and said cathode in an input circuit, an impedance-connected in serieswith the said first electrode, a condenser between said first electrode and said cathode, and-a condenser of relatively large capacity connected between said 5' second electrode and ground whereby an excessive positive swing of signal will cause a potential drop across said resistive impedance which drop is impressed on said grid and current is diverted through the input circuit by rectification. 10

the time constant being fixed by said condenser and said impedance inserles with said first electrode.-

i PHILIP M. m.

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