US1908920A - Thermionic valve - Google Patents

Description

May 16, '1933'. J. RoBlNsoN THERMIONIC VALVE Filed July 6, 1927 deffejo Patented May 16, 1933 UNITED STATES JAMES ROBINSON, F LONDON, ENGLAND THERMIONIC VALVE Application filed July 6,1927, Serial No.' 203,

This invention relates to thermionic valves having a. single cathode or lament, one or more control electrodes or grids and one or more plate electrodes or anodes.

According to the invention such valves are provided inside their envelopes with additional juxtaposed elements of similar physical character to the anode or grid, which are herein called grid elements and anode elements because one or other of these elements, but not both ofthem, may be an extension of or directly connected with the grid or anode of the valve, and such connection is the only permanent connection within the -valve between these additional elements and any of the valve elements. Fur ther, these elements are, by means other than screening, placed effectively or substantially outside the cathode field, that is to say there is no flow or comparatively little iow of electrons from the filament through the grid elementto the anode element, with the resultvthat these juxtaposed elements fulfill only `one of the functions Aof a valve grid L' and anode, viz. by their capacity they allow high frequency Veffects to pass between the anode and the grid circuits. When the anode element or the grid element'is an extension of the valve anode or grid respectively, only that part of the element which is outside the electron stream constitutes the anode element or the gridelement, as the case may be', in the sense in which these terms are herein used.

These additional grid and anode elements are of the same` physical character as the grid or anode of the valve, that -isto say they have extended metallicA surfaces which in their juxtaposed position constitute a cons 40 denser having a capacity of the saine order as the grid-anode capacity of the valve, and when it is desired to have these capacities exactly equal, the additional grid and anode elements are made physical duplicates of the valve grid and anode.

Such thermionic valves in one form or another are of utility as current amplifiers or as frequency multipliers, or for balancing out disturbances due to irregularities or changes of emission such as are obtained 783, and in Great Britain November 30, 1926.

when the filament is heated by alternating current. In the latter case the extra anode and extra grid, if employed, need notl be used for the high frequency or low frequency wirelesseii'ects, but will be used to 55 obtain an anode current which varies with theemisslion from the filament. This varying anode current in the second anode can n ow be employed to counteract variations y of anode current from the first anode;v or again, it may be used to vary the potential of the 0rid so as to keep the anode current in the rst anode independent of variations of emission.

The subdivision and arrangement of thefl5 elements of the various types of valves contemplated are ,illustrated diagrammatically in Figs. l to 4 ofthe accompanying drawing, while Figs. 5 and 6 illustrate also diagram- Amatically two constructions of valves of the170 type'shown in Fig. l; Fig. 7 illustrates the applicatipn of sucha valve to nigh frequency amplification; Fig. 8, a modified arrangement having the same object.

The valves shown in Fig. 7 have their 75 elements arranged in the manner shown in Fig. l, while the valve shown in Fig. 8y is of the kind illustrated in Fig. 2.

In the type of valve shown in Fig. 1, the anode is subdivided while the grid is undivided. The two portions A, A of the anode may be identical, but are not necessarily so.

In Fig. 2 the grid is subdivided, while ,the anode is undivided. As shown, the grid 85,

is divided into two portions G and G and these portions may be identical in each case, or are unequal. The filament F may be asymmetrically disposed with respect to the grid and anode. Y i

In Figs. 3 and 4 both the anodeand the grid are subdivided. These subdivisions may be equal and` symmetrically disposed with respect to eachother, but are not necessarily so.

The anode portions may be cylindersv A,

lA placed end toend as shown in Fig. 5,

or side by side Yas shown in Fig. 6, and separated fromy each other so that there is no direct electrical conduct-ion between thein,;10(E

and the lament F may be co-terminous with one cylinder, while the coil-shaped grid G, which in Fig. 6 is shown as being in two conductively connected parts, extends along the entire length of both cylinders, which may be equal and symmetrically disposed with respect to the grid. Instead of having a double or divided anode and a single grid, there may be a double or divided grid and two anodes or a single anode extending along the length of both grids, the filament being co-terminous with one grid only or with both.

Obviously more than one of such special valves can be combined in one container. In this case the filaments can be arranged to'bc in series orin parallel; for example, a convenient unit is two such special valve elements and one ordinary three-electrode element to act as a rectifier inside one glass envelope.

Valves constructed in accordance with the present invention may be employed, e. g., for vhigh frequency or low frequency emplification, and Fig. 7 illustrates diagrammatically the use of two such valves for twost-age high frequency amplication.

As shown, capacity coupling is used between the two valves, but inductive coupling can be substituted. It will be seen that the two portions of the anode A, A in each of the valves V, V `are connected with the ends of the anode inductance coil I, which is preferably tuned by a shunting condenser C. Preferably also the high tension battery is connected with the divided anodethrough a central or variable tapping point X on the anode inductancecoil I. In this case it will be noted that only one portion of lthe anode, namely A, is in the effective field of the-gridv and filament, the latter being coterminous with the anode A. v y Fig. 8 shows diagrammatically a construction of valve in which the grid is divided into two parts Gr, G', while'` the anode A which is co-extensive withthe two grids is undivided, the filament F beingco-terminus with one part of the divided grid, namely part G. The two parts'of the divided grid are connected ldirectly with the 'ends of the gridcoil K which is tuned by means of variable condenser O shunting the ends of the grid coil. A tapping Y (which 'may be central or adjustable) on the grid coil K is joinedvtofilament F through any potential device required,'as for example a battery and potentiometer.

These special valves may be combined for different purposes in various ways with each other, or with ordinary three-electrode valves. 'For instance, three valves such as shown in Fig-8 may be used for three-stage lhigh frequency amplification followed by an ordinary' three-electrode valve acting as 'a detector vand oscillator, that is' to say this of: carrying the same into practical effect,

I claim j 1. A thermionic valve having a single filament, a control electrode and plate electrode and a plurality of additional juxtaposed elements of similar physical character to the said f electrodes and disposed substantially outside the cathode field, the filamenty being asymmetrically disposed with respect to the valve electrodes and lthe additional juxtaposed elements.

2.' A thermionic value according to claim l, whereinA the additional juxtaposed ele- Vments have substantially the same reactance to high frequency currents as the grid anode capacity ofthe valve.'

3. A thermionic valve having a single filament, wherein besides the control and plate electrodes of the valve there are provided inside the envelope additional juxtaposed elements of similar lphysical character to the said electrodes of the valve, one-of which additional elements, but not both, being directly connected with one of the said electrodes of the valves, such connection being the only permanent connectiony within the valve between these additional elements and any of the valve electrodes and these additional elements being located substantially outside the cathode eld.

4. A thermionic valve according to claim l, wherein the additionaljuxtaposed elements are placed effectively outside the cathode field by an appropriate asymmetrical disposition of the cathode with respect to the valve elements and. the additional juxtaposed elements.

In witness whereof I have signed my name to this specification.

JAMES ROBINSON.

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