US1733603A - Electron-discharge device - Google Patents

Description

Oct. 29, 1929. J JOHNSON 1,733,603

ELECTRON DISCHARGE DEVICE Filed July 2, 1925 lm emor: Ja/m .5. Job/20m Patented Oct. 29, 1929 uni-Tan snares JOHNiB. JOHNSON,',OF ELMHURST," NEVJ YORK, ASSIGNOR' TOWESTERN ELECTRIO COMQ PANY, INCORPORATED, 0F-NEW YORK, N. Y., A CORPORATION OF NEW- YORK? I 'nnncrnon-nrsormnen DEVICE Application filed July 2,

This invention'rel'ates to electron discharge devices an'd circuits employing the same, and particularly electron discharge devices employing thermionic cathodes and circuit arrangements for heating the cathodes with fluctuating current.

One ofthe'olijectsgof the invention is'to improve the action'oit an electron discharge devise;

A furtlierohject of the invention is to prevent" disturhancesfinfthe output of an electrondiscliarge device due to'vari'ations in the cathode heating current. i

It is often desirable toheat' thecathode of electron discharge devices bymeans'oitv current from an a'lternating or varying-source ofipotential. \Vhen this is: done, however, the potential het'weentlie cathode and control electrode and between the cathode and anode varies in accordance With the voltage impressed on theYcat'hode, thus producing fluctuations A in a the output current, ofthe devicei I In accordance with this invention; the oath- OdE control electrode. and' anodie'are arranged in parallel relationship Within an enclosing vessel and taps Brought out from both ends oi each. electrode, so that a voltage equal to that impressed on the" cathode for heating maybe impressed on both the control electrode and the anode. Adjacent pointsonjthe three electrodes are thereby maintained at the same potential irrespective of variations in the cathode heating current and no changes Willhe' produced in thespa'cecurrent thereby. I VlZhen the cathode oit' 'an electroirdischarge device is heated by means of an electric current flowing therethrough the two terminals of the' cathode Will be at different potentials duertotheRI drop; i Vhen theordinarytype of anode is employed and this anode main.- tainedat a definitepotential With respect to the cathodeby' means of" anexternal source, the; anodecathode potential will vary at differentp'oints' along the'cathode; As is Well recognizediirthe art the output of an electron discharge device is Within certain limits dependent noon the anode-cathode potential. Therefore, if the external source is adiustod to such a value as to give maximum efficiency 1925. Serial. No. 41,051.

PATENT oFFrc-Ej l of oneration other points on thecathode' will i be operating'at ineiiicient potentials'and the entire area of the'catliode Will not be used to the greatest advantage; Theideleterious results of. this effect Willhe most pronounced in devices provided With cathodes of? considre erahle length Where a large cathode area is desirable for giving, a, high energyioutput'.

The arrangement" of this invention. above described Which the three electrodes-Tare arranged parallel and the same long tudinal potential impressed" thereon. to maintain ad jacent pointsat the same potential? makes'it possible to maintain allpoints onithe cathode A three-electrode vacuumtubeg 3;- having-a I filamentary cathode 4, agcontrol electrode or grid 5 and ananode6 arrangedfa'ccording to this lIlVentlOIllS showninan" ainp hhercircu t equipped with means for heating the, 'cath-l ode with alternating current, the electrodes are merely shown diagrammatically as any particular form" is notmaterial to the inv'ention. The grid and anode are arranged parallei toone another and to-thecathodeand each is, provided with terminals at both ends. WVhile it is preferahl'e to make the electrodes of parallel wiresarranged non-inductively so as not to introduce any magnetic "fields which \vould'afiect the electron stream, the grid and anodemay readily be con structed of parallel plane, cylindrical? or other suitable shape.

The grid and anode must be of comparatively high resistance so as not to be heated when a voltage equah to thecath'ode voltage is impressecha'long them, While the cathode is made in the usual manner so that it is heatedto incandescence to give *oifflelectrons.

Filament heating current-is supplied from 9 an alternating current source 'Z; through a transformer-8 which is provided with a p'ri' mary Winding 9 connected to the source Tthrough a rheostat 10. A secondary Winding 11 of tlietran'sformer is c'onneote'dlto'the cathode 4 for supplying current thereto. Two other secondary windings 12 and 18 are also provided for applying equal voltages across the grid 5 and the anode 6. These windings each have the same number of turns and'are wound in the same direction as the winding 11, so that equal voltages of the same phase are impressed on the electrodes to maintain adjacent points on all three at the same potential. By connecting the rheostat in the primary circuit the filament current can be controlled without affecting the equality of the electrode voltages.

The tube is associated with the other apparatus in the amplifier circuit in the usual manner, the connections to the electrodes preferably being made at the electrical centers of their respective transformer windings so as to keep the inductive coupling'between the input and output circuits at a minimum. Thus the secondary winding of the input transformer 14 is connected in series with the grid biasing battery 15 to the mid-points of the grid winding 12 and the cathode winding 11 while the receiver 16, representing the output circuit, is connected in series with the plate battery 17 to the mid-points of the anodewinding 13 and the cathode winding 11. If it is desired, the mid-point of the cathode winding may be grounded by means of a connection 18. r

The invention has been described with respect to an audio frequency amplifier circuit but may obviously be applied to other circuits such as detectors, high frequency amplifiers oreven oscillators if desired.

- -What is claimed is:

1. An electron discharge device comprising a thermionic cathode, a control element and an anode arranged in parallel space relationship, means for supplying alternating heating current to said cathode, and means 7 ing current thereto, andmeans for impressing an equal fluctuating potential from the same source on said control electrode to prevent fluctuations in said heating current from producing disturbancesin the space current of said device.

4. An electron c ischarge device comprising a thermionic cathode, a control electrode, and

an anode arranged in parallel space relation- 7 I cathode heating current.

ship, means for supplying fluctuating cur-' rent for heating said cathode, and means for impressing current from the same source on said control electrode and anode to always maintain adjacent points on said three electrodes at the same potential with regard to the cathode heating current.

5. An electron discharge device comprising an enclosing vessel containing a thermionic cathode, a control electrode, and an anode arranged in parallel space relationship, means for impressing alternating current on said cathode for heating the same and means for impressing alternating current of the same potential and phase on said control electrode and anode to maintain adjacent points on said three electrodes at the same potential.

6. In combination, an electron discharge device having a thermionic cathode, a control electrode and an anode arranged in parallel space relationship and eachprovided with terminals at both ends, a source of alternating current and a transformer having a primary winding connected to said source, a secondary winding connected to the terminals of said cathode for. supplying heating current and two other secondary windings having the same number of turns as said first secondary winding connected to said control electrode and anode, respectively, for impressing thereon a potential of the same phase and equal to the potential impressed on the cathode to maintain adjacent points on saidthree electrodes at the same potential with regard to the 7 An electron discharge device comprism a filamentary cathode, a control electrode,

an anode, said control electrode and anode being arranged parallel to one another and to said cathode and being of comparatively high resistance so as not to be heated to incandescence when a voltage equal to the oathode voltage is impressed thereon, means for supplying an alternating current to said cathode for heating and means for impressing an alternating current of the same phase and voltage on said control electrode and anode to maintain adjacent points on said three electrodes at the same potential.

8. An electron discharge device comprising a thermionic cathode, a control electrode, an anode, a source of alternating current, and means for heating the cathode by said alternating current and for impressing alternatingcurrent from said source in the same phase

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