US2616043A - Electronic oscillatory device - Google Patents

Description

Oct. 28, 1952 H. M. O'NEILL 2,616,043

ELECTRONIC OSCILLATORY DEVICE Filed Feb. 16, .94s 2 saEE'rs-sl-lEET 1 Oct. 28, 1952 H. M. O'NEILL 2,616,043

ELECTRONIC OSCILLATORY DEVICE Filed Feb. 16, 1946 2 SHEETS-SHEET 2 Patented Oct. 28, 1952 UNITED STATES PATENT OFFICE 2,616,043 a I v ELECTRONIC QSCILLAIQIQY. DEVICE.

Henry Murray: QNeill, Pompton lilains N. J; Application February 16, 19.46, Scria1N0- 68,l2.

4 Claims.

This invention relates to the utilization of the oscillatory activity of electrically-charged particules in avacuum.

It isan object o-f my invention'to provide an electronic oscillatory device having a vacuum tubelin which electrons may be. held initially in static equilibrium within the evacuated space, andso arranged as to number and distribution that, when the device is acted upon'by alternating; voltages, the electronic space charge will be set into oscillation in such amanner that the device will display to the alternating voltages the properties of a parallel-resonant circuit and, alternatively, the properties of an amplifier of the, alternating voltages.

This invention further contemplates the generation of alternating voltages.

Other objects and advantages of theinvention will become apparent as the description proceeds. Reference will now be made to the accompanying drawingswherein like reference numerals indicate like parts.

Figure 1 is a simplified schematic view of a.

basic former invention as an electronic oscillatory device.

.Fig u re 21s a simplified schematic view of a modified form of the invention as a push pull amplifier. v

Figure 3 shows a fragmentaryipartly cross-sectionallviewof one form-of electronic .tube which,

may .be .used to realize the advantages of this invention.

Figure 4 shows an elevation view of another form of tube which may be used.

Figure 5 shows .afragmentary partlycross-sectional view of still another form ;of electronic tube which maybe used.

Referring toFigur-e 1, an-evacuated envelope or tube is-rshown -at I, which maybe of glass or other insulating material. In the end regionsof tube .lare cathodes 3- and -5 activated by power sources J and, 9,v preferably through variable resistances 1.8 and in. Electrically connectedto cathodes.3.and5-are reflectors H and I3. It is notessentialthat tube I have two cathodes, but it is recommended that both reflectors H and l 3' b e provided. An anode 2i :to be describedlater, .-is shown in the central region of tube I and ;D,.;.C'. source I5 is connectedto reflectors--,ll and -I3 through choke coils H and 1 9 and to anode; 24 infillch armannerthat reflectors 3H and Iii-are normally at a potential negative with respect to ground. The purpose of the-elements justdescribed is to produce a charge o r-electrons inside .tube land to hold the-charge of electrons normally-in equilibrium between reflectors ll and I3. With electrons thus held in equilibrium in the,central region of tube .Lreflectors {I l and 13 maybe .actedpn by. oscillation generator 21;. cone nected to .theureflectors through ;D. C. blocking 2. condens Z an 3t h ha ge of e rons. may thus be made to oscillate in response'to the alternating voltage suppliedby oscillation gen; erator 2:1. 1

Anode -21 has been referred to above. In one fIorm as shown in Figures 3 and 5 anode M will be an annulus so placed. that its inner surface. lies in contact with the evacuated space but slightly .depressedwith relation to the innersure faceof the glass envelope, to the end thateliec trons passing through the central region will have. alow component of velocity towards the anode. Anode 2 i is ccnnectedto resistance -23 which may be either fixed'or variable and which in turn connected to the grounded or ungrounded positive side of 13-0. source 1.5. Reference character 25 designates a capacitance connected acrossresistance 23. In Figure 1, ifoscillati on generator zlris inactiv bu ca e 'fiand 5 a e ctie vetted by po r ource 1 a 9 1, C: our-9e 4. will cause a current to flow from the D. vC. source to cathodes ,3 and 5 to anode-2-l and thence baclg; to D, C'. source I15 through resistance 23. i'lc sustain the currentagainst the negativepotential of anode- 21- caused by the voltage dropacrcss resistance 23 and against the repulsionef -elece trons further, advanced along the path to the anode, an electronic space charge will 110 the central region cf tube Y I f =the rate of elect on flow uwardsthe tral reg-ion of tube; I is li-mited by 1 ilament satu;-. tion i t e cathq e .32 and 5 orv b. t e ut er: pe -ti u :oi .-1. eeat e1y-b ase rids in the clue: nicpeth the; anode. or by ether-me ns; the n gative v ltag a pl ed t0 reflectors H and 3 may be so adjusted hat the s ace charge w 1 -c0 ist of a small number .u h h welucity ectr n in heflr g sof the ua hudes a a. r t-n mber ufi-el ctrous movi h t en u ty nea -theauode. o at ofhe es n dis ussi o t e uveutiuni he pri c pal ma s o the ele t n e regarded ing held in tat c qu br um. y. the-neg t towards the less negative reflector. This movement is an electric current which will set up a magnetic field in which energy is stored while the electrons are being accelerated, to return it to them in support of their velocity when they begin to slow down. The amplitude of the current is determined by the number and velocity of the electrons.

The standard definition of electric current defines a-flow and not a velocity. The definition is satisfactory for closed metallic circuits where the positive charge produced by the departure of an electron from an atom is neutralized by the arrival of a following one, so that all of the free electrons present may take part in the movement around the circuit as a cohesive mass, but is less applicable where the electrons must be regarded as a limited number of discrete particles.

In the invention, for instance, all of the electronsof the space charge might, by some means, be compacted into a single plane and the plane caused to'osclllate back and forth. Then, except for the very end regions of their path, the electronic flow past every point would be the same, but the velocity of the electrons in the center of the path might be vastly greater than where they come to rest. Since the intensity of the magnetic field surrounding an electron is proportional to its velocity and in a metallic circuit the magnetic field is proportional to current, the difficulty with the standard definition of current is apparent.

Since, by definition, an electric current is a flow, the expression for the energy stored in a magnetic field involving current and inductance can be reconciled with a similar expression for the invention involving the number and velocity of the electrons only if, in the latter, the number of electrons is inversely proportional to their inductance. That this is true may be shown by a simple explanation.

If two electrons having the same velocity and direction are moving in tandem, their inertia will be due to the magnetic field of each referred only to its own electron, and to the gravitational mass of the electrons. If the two electrons are moving as a pair, however, their two magnetic fields will interlink and each electron will tend to force the other in the opposite direction whenever any change in their velocity takes place, thus giving to both an inertia not due to an increase in the total energy stored in the magnetic fields and hence more nearly gravitational in effect. It follows that, in the invention, the more the electrons are compacted towards the central region, that is,

the greater their inductance, the smaller will be the number required to produce a specified total of electrical inertia, but with a corresponding reduction in electromagnetic action, when the mass moves with a given velocity, either in free space or in any following circuit.

With no space charge present, the reflectors II and I3 will have a definite capacitance to the treminals of generator 27 which will be unaltered by the negative voltage applied thereto, although this voltage will apply a negative charge to each of the reflectors I I and I 3 upon which any charge from the generator will be superimposed. When the space charge is introduced, the repulsion of its negative charge will reduce the negative charges on the reflectors I I and I3 and make their relative magnitudes dependent upon the position and symmetry of the space charge. Movements of the space charge can therefore produce a charge and discharge of the reflectors I I and I3 which is not necessarily in phase with the charge and discharge of the conventional capacitance produced by the generator voltage. If blocking condensers 29 and 3E, and choke coils I1 and I9 are adequate to their respective purposes, this electronic capacitance will react only on the generator; and if for some frequency the two capacitive reactions are equal and opposite. the reflectors II and I3 will be non-reactive to the generator, provided any variations in cathode to anode direct electronic flow are small enough to be neglected.

In the resistanceless case if the circuit from generator 21 to the reflectors II and I3 is closed at the instant when its alternating voltage is at a peak, the space charge will begin immediately to move towards the reflector to which the positive peak of alternating voltage is applied, driving electrons freely out of the latter towards the positive terminal of the generator, with a reciprocal action occurring at the opposite reflector. Being unopposed, the space charge will be continuously accelerated until the instantaneous alternating voltage difference between the reflectors I I and I3 falls to zero, with energy being stored by the space charge throughout this time interval to sustain its velocity after the acceleration ceases.

When the generator voltage begins to go negative to the nearer reflector, it will begin to resist the free flow of electrons therefrom. The effect of this is to build up a force of repulsion between the reflector and space charges which is directly proportional to their product and is an inverse function of the distance between their electrostatic centroids. If the alternating voltage is low enough, but within certain limits imposed by the device, the moving space charge will have enough energy stored by it to continue driving electrons away from the reflector until the associated generator terminal reaches a negative peak of voltage. At this instant, because the line integral of the force opposing the motion is now equal to that which produced it, the movements both of the space charge and the electron flow with respect to the reflector must reverse themselves.

Because of its displacement from the position of central equilibrium the space charge will be more rapidly accelerated on its return journey than during the initial quarter-cycle with the result that, during this or a subsequent movement, it will reach its maximum velocity at the instant when it is again symmetrical about the central anode and moving in the direction of the reflector then about to go negative to the alternating voltage, and the instantaneous alternating voltage difierence between the reflectors, of necessity, is zero. Considerations of symmetry will show that for any frequency steady state oscillations will be possible only under these last conditions. Therefore, the charge and discharge of the electronic capacitance of the reflectors, Whenever the space charge is acted upon by a single alternating force, will always be diametrically opposed to that of their conventional capacitance and hence the effect of the former is that of an inductive reactance.

The reactance of the device will be purely inductive for low frequencies. As the frequency is increased, however, the displacement of the space charge and hence of the reflector charge in phase with it will decrease while the charge and discharge of the conventional capacitance per cycle remains constant. Therefore, at some creasing: with increasing frequency. These arev the conditions which obtain in a parallel-rescham-network.

If the cathode to anodedirect currentsdo not vary during the operating-cycle, they will not affect f. resonance regardless of j their amplitude.

If they do va'ry, they will cause a charge and diseharge ot thereflectors which, if diametrically cppcsed to that tending to be produced by the generator voltage, will serve to increase the inductive current and resonant frequency. If the phase relation-is other than this, the space charge will shift the phase of its oscillations to respond: to-the-resultant, the efiect being that of adding series capacitance tothe parallel network. Whenresistance is present, the initial displacement of the central space'char'ge will fall short of wh'at it should beandthespace charge will turn back before the charge of the reflectors by the generator is complete. Whensteady stateoscillations have beeh attained,the charge and discharge of. the reflectors willremain out of phase with thegenerator voltage-and thus replenish the energy being lost by the spacechar'ges.

Thespace charge may also be set into oscillatien byan alternating field cou led to it either from-a metallic circuit or asimilar' space charge; In this case thecharge and discharge of the reflectors caused by the movements of the space charge -will' produce currents and voltages 'for the-operation of a following network. Furthermore, in view-of the facts that the proportions of the electromagnetic and-inductive inertias of the space charge-can bevaried while maintaining the total constant and'tha't only the electromagnetic inertia will afiect a coupled circuit, the degree-of coupling can be altered simply by varying the D. C. potentials applied to reflectors andanode without affecting resonance.

When the space charge is moving with high velocity; few electrons willhe absorbed by anode 2! because their velocity parallel to its surface w-ill'be high compared to thatnormal to it. Capacitance 25 is intended to maintain the potential of the anode reasonably constant during the cyclic variation in electronic absorption. Anode 2| may be completely external to the evacuated spacepf the invention and both re- Sistance 23 and capacitance 25 dispensed with; but tnthis form of the invention the number and-- distribution of the electrons in the space chargewould be more diiflcult to control. If grids are-interposed between cathodes and anode forthe purpose, their effectiveness will be limited unless a variable impedance network is used to divide the-output voltage'of generator 21 between reflectors and grids.

-Two effects pertaining to inherent properties of theinvention will now be discussed. The first arises from the fact that thespace charge is not a 'rigid mass but is capable of compression within itself. The second is'the modification of the action of the space charge which will take place ifxuseis made :of :an external .positively charged anode.

- Compression within the. central space charge will. vary as it "approaches or leaves a; reflector depending on how loosely the electrons are compacted initially. This will produce an effect equivalent to that of the distributed capacitance of aooil. As is. well known, distributedxcapaciage charge write 6'. taince can produce the effect of parallelareso nance in a coil without the aid of any other capacitance. Consequently, in the invention; even though the inter-reflector capacitance were negligible, resonance could occur. resonance seems to require that groups of elec-' trons in the end regions become motionless while:

oscillations continue in the more central region;

This can: happen because the reflector charge with its fixed location but variable number. of electrons can-exactly counterbalance theeifect; ona nearby group :of space electrons, of the r8139. tively fixed number of electrons but variable position of the central part of the /space charge As the frequency is increased above resonance; the electrons in the end. regionsof space will begin to movecounter to the direction ofthe. more central mass, thus making the net effect of the space charge, as seen. from the reflectorsm'ae pacitive rather. than inductive as. hitherto de-s scribed. l

The action considered above is progressive v'rthv frequency, the three groups of space electrons tending to sub-divide into five, with the two new groups taking both from the central mass and the first two end groups and the overall efiect'becom ing oncemore resonant and thenagain inductive. to the reflectors in a manner analogous to thesuccessive resonant points of a metallic'antenna. This theory is subject, .of course, to "the modifications introduced by :the fact that changes .;in-. velocity :of electrons. are not transmitted. from; oneto. another instantly but with :the speed-of: light.

The "capacitance established by the dimensions. and spacinglof the reflectors was shown-to be resonantefrequency determining quantity; .This ca'pacitancecanbe .increasedby extending the: reflectors externally to the evacuated spacetand reinforced wh'ererdesiredby additional fixedfor variable capacitance 'across' the reflectors. Skim. effectrwill. cause the space charge, when in mo-f tion,..to press-against the inner surface-of the tube I :and thus produce what may prove :toxbe, insome applications, Ian objectionable power loss. One means .of 'focussing the selectronsmore'ztm wardsthe 'axisof their movement is toydivide the reflectors concentrically to :this axis, in: the region'of'theglass Wall..'of the envelope. The two parts may then have difierent negative voltages applied to. them through separate choke :coils, withzithe "more negative voltage applied touthe outer ring, but may be capacitively coupled :for unity ofv action with respect toan alternating voltage...

For :simplicity and economy in: design, the invention may be modified byhaving ,a-cathode;at onlyrone end of tube 1, with a-reflector alone at the other end. Neither the symmetry of the spacecharge nor the-theory of operation -.will.be appreciably affected by this change. Two-or more anodes in regions approaching thereflectors andcontrolledv as to potential either separately-or together, with the space charge extendinglto wards the central region as before, are also contemplated. It is. intended that tube .1 may have anydesirable form whatsoever, and more particularly arform which'will facilitate the estab lishment of 'atlarger space charge, such as one havingya larger cross-section in the central region than in the end regions, as shown in Figure 4. Also, the use-of a double-walled tube withrthe evacuated space between the walls is envisaged, as shown in Figure 5, where theouter wall is, denoted :by la and the inner wall by lb;

Space charge The reflectors may in this construction be divided into two portions, annular portion Ho and cylindrical portion Ilb.

Thus either by the mechanical restrictions imposed by walls of glass or other insulating material or by the action of axially graded electric fields or both, it is possible to confine the space charge, when at rest, within the ring-shaped or other zone normal to it when in motion.

The invention originated in an extended search for a short device to replace the long wires used for the radiation and reception of electric waves. The amount of energy supplied to the radiation field, in either case, will depend solely on the number and velocity of the electrons producing the field, with a reciprocal relationship for reception. In a metal wire antenna the active electrons are so strung out along its length that their inductive effect upon one another may be small and their number large as compared with the H closely compacted electrons of the invention. On the other hand, the velocity of the electrons will be checked only by the losses of power either by radiation or internal or local to the radiator. As a conductor of electrons, evacuated space is so nearly lossless compared with any metal that the possibility of high efficiencies of radiation and reception is apparent even with much higher relative inductances.

Referring now to Figure 2 of the drawing, this differs from Figure 1 principally in that grids 33 and 35 negatively biased with respect to ground through choke coils 31 and 39 by D. C. Voltage source 4 l are shown interposed between cathodes and anode. applying its voltage to grids 33 and 35 instead of to the reflectors II and I3, this is an alternative and not an essential change. The principal difference in operation is that, in the form shown in Fig. 2, the cathodes are required to supply eleccharge back and forth by electronic impulsion.

With these differences in view the space charge may be regarded as being established substantially so described for Fig. 1, but with the cathode to anode currents determined by the magnitudes of the space charge and the negative charges of cathodes reflectors and grids.

If, now, grids 33 and 35 are excited by an alternating voltage from generator 21 which never exceeds the cut-off value for the cathode to anode currents, the total electron flow towards the anode will remain the same as for the steady grid voltage but will vary cyclically in volume from one end region to the other, thus creating an alternating force against the space charge which will depend on the instantaneous differences in the number, velocities and positions of the electrons moving towards the space charge from the two end regions. This force will cause the space charge to oscillate at the frequency of the alternating grid voltage.

The area of the grids 33 and 35 is assumed to be so small that their electronic charge is not a resonance-determining quantity, while the inter-reflector capacitance is not, as in Fig. 1, connected across generator 21. Each of the reflectors,

however, in addition to the inter-reflector ca- P Although generator 21 is shown as 8. coils l1 and I9 tending to maintain the direct electron flow constant, there will be a charge and discharge of these capacitances reciprocal to the amplitude. of the cathode to anode electronic flow. The movement of the space charge will be towards the cathode whose charge with that on its associated reflector is increasing and will continue, due to the momentum imparted to its mass, after the electronic impulse from the opposite cathode has ceased. The space charge will turn back when the electrostatic centroid of the reflector charge and its projection towards the space charge due to the release of electrons through the grid is close enough to that of the space charge to bring it to a halt. The space charge will oscillate with maximum amplitude and present the effect of a pure resistance in the cathode to anode circuits, when it is so proportioned to the reflector charges that the space charge comes to rest at the instant when the electronic current towards it is at a maximum, that is, when the grid reaches its positive peak of alternating voltage.

Since the momentum imparted to the space charge depends on the instantaneous difierence between the two cathode to anode currents, it is desirable that the current from each cathode be cut oil during at least a half-cycle of each alternation. If the grids are so biased. resistance 23 may be readjusted to establish resonance for a new average rate of electron flow, but variations in the amplitude of grid excitation will detune the space charge. This can be prevented by maintaining the voltage of anode 2| substantially at the value negative with respect to ground required for resonance by means of a direct current through resistance 23 provided by any power source through a suitable choke coil. Electrons will then be taken from the space charge only when the electronic pressure on the anode raises its voltage to or slightly above the value determined by the power source. This connection will improve the power efiiciency of the device itself but apparently not that of the circuit as a whole. Furthermore, since the negative voltage of anode 2| is a resonance-determining quantity, the invention can be frequency-modulated, either in an oscillator or otherwise, by applying an audio or other frequency voltage from a generator suitably connected across resistance 23.

In a conventional vacuum-tube amplifier, most of the momentum of the electronic impulses is abrupty lost as heat to the anodes where, in addition to the heating problem, the discontinuity in velocity coupled with the uni-directional conductivity of the anodes leads to transit time difficulties at high radio frequencies. In this invention, the anodic effect of th space charge is completely bi-directional; there is no discontinuity in the velocity of the electrons because the momentum of the electronic impulses is gradually imparted to the space charge; and comparatively little heating will occur within thedevice because the electrons leaving the space charge ordinarily fall through a very small voltage difference in striking the anode. While heating will occur in resistance '23, this element is external to the device where the problem of heat dissipation is more easily solved.

A contributing factor to the amplifying properties of the device of Figure 2 of the drawing is that the charge and discharge of the reflectors act in synchronism with the grid voltage varia-' tions to determine the magnitude of the electronic impulses towards the central space charge.

If the inter-reflector capacitance is great enough, the oscillatory activity of the space charge will be reinforced until it takes control and the device becomes self-oscillatory.

Generator 2! may then be dispensed with and the grids used only as negatively charged elements to aid in controlling the duration but not directly the frequency of the electronic impulses towards the central region. As a simplification the grids themselves may be eliminated and the form of the oscillator reduced to that of Figure 1 of the drawing.

It is to be noted particularly that in these simplified oscillators the varying reflector charge need not reside in the metal of the reflectors but may be in the adjacent evacuated space, as discussed in connection with Figure 1 of the drawing. The oscillatory activity will then take place entirely in space, with the metal members serving only as boundaries to this activity and as carriers of the constant amplitude direct currents which provide the driving power of the oscillator. It is at once apparent that since the metal members do not limit the upper frequency, generation and utilization of waves of extremely short length is possible.

The description discloses an electronic counterpart of the metallic tuned circuits used in the radio and allied arts. In a usual form it provides a charge of electrons held in space in neutral or unstable equilibrium to two other countervailing and mutually opposing charges; but by a transition of values it can graduate to a charge of electrically-charged particles held in space in stable equilibrium to an external positive charge. The invention is capable of replacing coil and condenser circuits, line tanks, cavity and wire resonators in a wide variety of combinations and applications of which only the most fundamental are described herein.

In a useful form, the invention displays the characteristics of a parallel-resonant circuit but it goes far beyond this. Modifications in the internal activity of the space charge or changes in the direction from which its electrical characteristics are explored can cause it to assume many other manifestations. If, when the space charge of electrons is acted upon by an oscillating electric force, it possesses in relation to the activating force the electrical equivalent of inertia, it is this invention. Where the expressions electric force or electric field are used in the specification and claims, they are intended to include any and all electromagnetic and electrostatic phenomena which may be applicable. Also where the device is referred to as a radiator of electric waves, its properties as a receiver of electric waves are intended to be included.

It will be observed that the invention in its basic forms has an outward appearance of great simplicity; but in the electronic art, invention may reside in the physical quantities which are the numbers, positions, velocities and directions of motion of electrons in free space, equally as well as in the metallic electrodes and other more easily represented parts of a circuit. So it is in the present invention. For these spatial activities, theories of performance rather than concrete physical representations have been referred to in the description. The intent of the inventor is to be held to the truth of matters of theory only to the extent that the essence of the invention will stand or fall thereby.

What is claimed is:

1. An electronic network comprising an evacuated envelope, electron emitting means within I said envelope, electron reflecting means in said envelope, anode means having at least one surface thereof exposed to the inside of said envelope, a current source attached to said electron emitting means, said electron reflecting means and said anode means, the negative side of said current source being attached to said reflecting means through R. F. blocking means and the positive side being attached to said anode means through impedance means.

2. An electronic resonator comprising an elongated evacuated envelope, electron emitting means within said envelope, a plurality of electron re-flecting plate means at least partly inside said envelope and disposed perpendicularly to the length of said elongated envelope, anode means having at least one surface exposed to the inside of said envelope and a current source connected to said electron emitting means, said electron reflecting plate means and said anode means with such polarity that electrons tend to move from said electron emitting means toward said anode means, and oscillation generating means connected to said electron reflecting plate means.

3. An electronic network capable of amplifying signals applied thereto or of producing oscillations comprising an evacuated envelope, electron emitting means within said envelope, a pair of substantially parallel electron-reflecting plates at least partly inside said envelope, and at least one of said electron reflecting plates being connected to said electron emitting means, anode means disposed between said electron reflecting plates, a current source connected to said electron emitting means, said electron reflecting plates and said anode means in such relationship that electrons tend to move from said electron emitting means toward said anode means and said electrons are repelled from opposite directions by said electron reflecting plates, the said current source being connected to said electron reflecting plates through R. F. blocking means.

4. A push-pull amplifier comprising an evacuated envelope, electron emitting means in said envelope, and anode having at least one surface thereof exposed to the inside of said envelope, two electron control means disposed substantially symmetrically about said anode, two electron reflecting plates disposed substantially symmetrically about said anode, at least one of said electron reflecting plates being connected to said electron emitting means, a current source having its positive side connected to the anode and its negative side connected to the electron reflecting plates through R. F. blocking means, the input to the said push-pull amplifier being received between said two electron control means.

HENRY MURRAY ONEILL.

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

UNITED STATES PATENTS Number Name Dat 1,128,279 Arnold Feb. 16, 1915 1,662,846 Clark Mar. 20, 1928 1,768,660 Brockett July 1, 1930 1,960,349 Schaberle May 29, 1934 2,005,782 Hansell June 25, 1935 2,079,248 Fritz May 4, 1937 2,123,242 Hollmann July 12, 1938 2,141,292 Clovier Dec. 27, 1938 2,300,052 Lindenblad Oct. 27, 1942 2,463,617 Hartley Mar. 8, 1949 2,476,765 Pierce July 19, 1949

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