US1853914A - Thermionic tube - Google Patents

Description

April 12, 1932. Q T` MC|| VA|NE 1,853,914

THERMIONIC TUBE Filed May 6, 1925 [mr/'entor- 10 u JTW 7| @MW y Y ttozzleys ject of the resent invention is the provision l Patented Apr. 12, 1.932

UNITED STATES y AORAAN T. MCILVAINE, EAST CLEVELAND, OHIO, AYSSIGNOR TO MCILVAINE PATENT PATENT OFFICE.

CORPORATION, F ST. CHARLES, ILLINOIS, A. CORPORATION 0F THEBMIONIC TUBE Application 'led May 6,

trons is to use a metallic fllament heated electrically, and it has always nheretofore been necessary Vto employ an absolutely steady direct current for .this purpose since any variation in the current caused similar variations in the reception wires. Thus the employment of alternating current produced a hum which obliterated all signals, and the customary mode heretofore followed has been to energize the emitting lament by the use of a primary or storage battery. The obof a tube o this character which can be connected directly to an alternatmg current supply of the requisite voltage and which will exhibit the same mode ofP operation as with a direct current source,'ent1rely without humming sounds or other noises; the provision of a new arrangement of filaments whereby variations in direction and potential of the current flow may be neutralized; while other objects and advantages of the invention will become apparent as the description proceeds. y

In the drawings accompanying and forming a part of this application I have shown specimen modes of applying my invention to a standard tube of one of the most widely known makes although it will be understood that I do not limit myself to kind, appearance, or type of tube and have chosen this solely for purposes of illustrating the essen-l tial idea of my invention without restricting y myself to the arrangement shown. Fig. 1

is a perspective view of a tube of the type described, portions of the elements being broken away in order to show the internal construction; Fig. 2 is an enlarged vie'w,of the filament and support, the plate and grid being entirely omitted; Figs. 3, 4, and 5 vare detail views showing other arrangements of 5o laments; and Figs. 6 and 7 are detail views REISSUED showing concentrated forms ofifilaments as desired for certain other types of tubes.

Practically all tubes comprise an evacuated glass globe 1, a supporting base 2, and

1925. Serial 'N0. 28,401.

certain metallic elements enclosed within'the l,

i tube and comprising in one guise or another,

a plate 3, grid 4 and filament 5, 6. Ordinarily this filament consists of a single circuit but accordingA to my invention I make said filament of even numbers of plural strands located close together and connected between the terminals of the alternating current in reversed positions, the filaments being so arranged as regards other elements that the electrostatic condition created by one lanient shall be neutralized by the other filament, with the result of producing a steady source of negative electrons.y

Thus, in the form shown in Figs. 1 and 2 the various wires are brought into the tube through a press 7 in which numerous wires are sealed such as the wires 8-8 which carry the plate, the wires 9-9 which carry the grid and the connections 10, 11, which VAcarry filaments. The connection 10, in addition to receiving` the lower end of the filament 5 also carries a bracket 12 terminating at its upper end in a hook 13 which supports the upper end of the companion filament 6. Likewise the connection 11 carries a bracket 14 which terminates at its upper end in a hook 15 to which is secured the upper end of the filament 5. Preferably in practice these brackets 12 and 14 are located outside of the tube elements as shown in Fig. 1. The filament and ,elements are connected to base contacts in the usual manner and in use the wires 10, 11 are connected to opposite ends .small voltage, the latter about 1/2 to 1 volt.

Thishas the further advantage of enabling the use of heavier and stronger filament wires than can be used in higher voltages.

If we'assume at any given instant that the =wire 10 is positive and the wire 11 negative,

due to the fiuctuations in the circuit, then the lower end of the filament 5 will be positive and the lower end of the filament 6 negative and at the same time, owing to the fact that the brackets 12 and 14 have substantially a zero resistance the upper end of the filament 6 is positive. In other words the A. C. wave starts simultaneously at opposite ends of the two filaments, and as the wave progresses, it progresses exactly the same in both laments, that point which was before highly positive gradually decreasing and that polnt which before was highly negative gradually approaching positive until the two reach the same condition, which occurs midway of the wave, after which the lower end of the filament 5 becomes increasingly negative and the lower end of the filament 6 increasingly positive. Considered in another aspect it can be pictured that alternating waves are constantly chasing each other up and down the respective filaments but are so related one to the other, that the algebraic sum o such waves at equal horizontal levels inthe respective filaments is always zero. This is readily seen at theiinstant of highest potential in one of the filaments, at which time the corresponding point in the other filament exhibits its correspondingly low potential, and if these filaments are sufficiently close together the electrostatic charge on the one exactly equals that on the other; and is likewisel true when as a result of the advance of a waved given point of one filament becomes zero relative to outside standards, at which instant the corresponding oint of the other filament should always ex ibit zero potential. As a result both wires are always maintained under sufficient temperature to produce an adequate supply of electrons, withont at -the same time causing the alternating A current of the lighting systems to infiuence the reception since a `positive condition at each point of each filament is exactly c ounterbalanced by an equivalent negative on the nearest segment of the companion filament.

These filaments may besupported and v looped in a great many modes without departure from the scope of my invention or avoiding this mode of operation. The arrangement illustrated in Figs. l and 2 is in many ways the simplest and most practical.

However, it is equally possible whenever desired to increase the number of filaments as for example by making them in small segments as shown 1n Flg. 3 1n which case the wires 10aL and 11a are provided with brackets 13', 13", 15a, 15b respectively adapted to support the segments tia-5a and 6--62 the lower ends of the segments being suitably connected to the other wires to which their respectlve upper ends were attached.

Another mode of arrangement is shown in Fig. 4 wherein the filaments 5b and 6b are connected at their upper and bottom ends to the wires 10b and 11b, these filaments being made ofv any suitable material. In the form of the invention shown in Figs. 1 and 2 I have shown tungsten wires. These may, if desired, have their emissivity increased by a lcoating of refractory earths such as thoria, and the greaterl thickness of the filaments as in Fig. 3 is intended to indicate this. In Fig. 4 I have shown these filaments 'as consisting of thin strips or ribbons of nickel, which also may, if desired, be treated superficially to increase the emissivity. In thiscase it is not necessary to keep the filaments apart at the center since this point always exhibits equal potential on the two filaments. In the form shown in Fig. 5 the filaments instead of making only one connection between the wires 10c and 11C are looped back and forth repeatedly. The forms shown in Figs. 6 and 7 are devised for a more concentrated arrangement. In Fig. 6 the supporting wires 10d and 12d are crossed but insulated from each other at the center their extremities being surrounded by filaments 5d, 6d here making a complete parallelogram; and in Fig. 7 the filaments 5e, 6e are shown as wound together into a double spiral, the ends being connected. to the terminals 10e, 11".

It is not important whether the filaments 5 and 6 be parallel to each other as they appear to be in Fig. 2 or somewhat 'inclined as in Figs. 1, 4, and 5, provided only that they be substantially parallel to the face of the anode and that they be symmetrical with respect to a straight line which is parallel to the face of said anode.- This axis of symmetry may either be vertical as in the form of Fig. 1 or transverse as in Fig. 5. Indeed in Figs. 4, 5, and 6 there are two rectangular axes of symmetry.

I have described the condition 'I have sought and here obtained by the expression that the electrostatic effect produced by one filament is neutralized by another filament, or that the combined, external, electrostatic effect of those filaments is zero. This concept possibly requires additional elucidation. It is the purpose of my invention to obtain thermal emission of negative electrons by the use of an alternating current. It has been known for many years that electrons are driven off' a metallic body by heating it. If the body be insulated from other bodies the number of electrons that can be removed is comparatively small since the abstraction of as the B battery used in radio work, especially if the other pole of the same battery be brought suliiciently near to receive the negative electrons so emitted.

When an electric current is used to heat l the body a second set of electrons is employed at the same time, the hypothesis being that this current is merely the passage of a different set of electrons through the body, and theheating electasymptom of resistance to the passage of those electrons. Although the two currents traverse the same body, namely the current which causes the heat and the current which causes the electronic emission, they are entirely separate and distinct and independent. It is hardly believed that the individual electrons which enter with the heating current always escape with that current and vice versa` any morethan the individual drops of water that enter a reservoir through two pipes leave that reservoir through any given pipes. Presumably the electrons are devoid of individuality so that it is merely requisite that the same number per second leave the body over the respective circuits as entered it by those circuits, but as long as the heating circuit lis uniform in potential its electrostatic effect can be ignored.

Now if the potential of either circuit be varied, the ratel of electronic emission must likewise vary; If the B battery be removed or made more feeble the number of electrons which can be released is likewise reduced; and if the body be heated by an alternating current its potential constantly in accordance with the phase .of the E. ML F. will vary and ordinarily tends to influence the elec-,

tron emission in like proportion. It is Jfor the purpose of neutralizing this effect that I employ plural bodies (in this case the filas ments l5, 6,) so arranged that when a given point of one shall be positive the correspondf ing point of the other shall be negative. This is expressed briefly by the statement that the combined electrostatic e'ect of the two bodies (filaments) is zero.

It appears not to .be necessary that the two bodies be so close together at every point as to effect such neutralization at every point; indeed it is arguable that this condition might cause the one which chanced momentarily to be positive to absorb all the electrons emitted at that instant by the other body. It is only necessary that their combined electrostatic effect upon adjacent bodies or elements as a whole should be neutralized, leaving the heating eiect free to release the electrons in the same manner as in the case of any other modeof heating. The fact that the result in view can be obtained by any one of the various arrangements of filaments shown here- `in indicates that it is the total summation effect which is important and not the detailed effect at `given points. This fact further indicates that numerous other detailed arrangements of laments and elements can be employed ,with successful results, wherefore I do not restrict myself to the arrangements, or designs, or connections herein shown, nor in any other manner except as recited in my several claims. .x

Having thus described my invention what l claim is: l

1. A thermionic tube having plate and grid elements therein, an even number of filaments, and'connections for conveying a heating current to said filaments, the latter being so arranged that each has a part lying substantially alongside a neighboring filament, andthe connections being so arranged that the instantaneous direction of flowin such parts ofthe two filaments is substantially opposite.

2. Avcathode structure comprising a plurality of parallel non-contiguous laments each having terminals and supporting members connected thereto adapted to conduct energy to the said filaments, adjacent terminals of the said filaments being connected to supporting members of opposite polarity.

3. A thermionic tube having therein an anode and a cathode structure and having external anodeand cathode-terminals and terminal provisions for av cathodeeenergizing circuit, said cathode-structure comprising resistance wire connected between said terminal provisions, each portion of such resistance wire being adjacent to but out of contact with another portion of such resistance 100 wire, which exhibits at every instant an opposite electric polarity from the first-named portion, whenever said terminal provisions are connected in circuit with a source of alternating electric current, whereby external 105 field effect of the cathode-heating current is neutralized.

, portions which exhibit opposite electric polarity when said terminals areconnected in circuit with the ordinary alternating current lighting system.

In testimony whereof I hereunto afiix my signature.

CRAN T. MCILVAINE.

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