US1169182A - Thermionic translating device. - Google Patents

Description

A. McL. NICOLS'ON.

THERMIONIC TRANSLATING DEVICE.

APPLICATION r1150 APR. 19, 1915.

Patented Jan. 25, 1916.

//7 1 61) for i NDER McLEAN NICOLSON, OF NEW YORK, N. Y., ASSIGNOR, BY MESNE ASSIGN- MENTS, T0 WESTERN ELECTRIC COMPANY, INCORPORATED, A CORPORATION OF NEW YORK.

Specification of Letters Patent.

THEONIC TBANSLATIN G DEVICE Patented Jain. 25, 1916.

Application filed Apr1l19, 1915, Serial No. 22,306.

ments in Thermionic Translating-Devices,

of which the following is a full, clear, concise, and exact description.

This invention relates to thermionic translating devices and in particular to vacuum tube devices in which the cathode element is heated by radiation from an adjacent heatin element, and its object is to produce a large current output with a. minimum number of electrode elements.

In a copending application I have described a form of so-called equi-potential cathode element forv use in a thermionic translating device, which element comprises a tube of quartz or similar material, the outer surface of which is 'ven a thermionically active coating, which is brought to incandescen'ce by means of an electrically heated resistance element located inside of the tube but the external outing.- The present invention contemplates the employment of this resistance or heating element as the input electrode of a translating device, and. is based on my discovery that the input electrode may be heated to incandescence Without interfering with the operation of such Figure 1 IS a device of the audion type employing the cathode and input element arrangement of this invention, and Fig. 2 illustrates diagrammatically how. the various electrodes of such a device may be connected into a typicalcircuit arrangement for the modification of telephonic or other currents.

In Fig. 1, 3 is an evacuated vessel, containing anodes or plates 4, and a plural ty of quartz tubes'5 the outer surfaces of which have thermionicall active coatings 6. A platinum spiral 7- is threaded through the tubes 5 iii-succession, as shown, and terminates on the two leading-m wires 8; The

' coating 6 is prepared as described in my copcnding application by applying a layer of platinum tetra-chlorid to the outut of electrical contact with side of the tubes 5 and baking. This produces a platinum deposit which in turn is coated by a mixture of the oxids of strontium and barium or other suitable thermionically active material. Leading-in wires 9 may be conveniently attached to the coating 6 b wrapping one end of the wire 9 about sai coating as shown at 10 and covering the joint thus formed with platinum tetrachlorid and baking. By connecting all of leading-in wires 9 to one terminal 11, the surface 6 may be made to function as a single cathode surface of large electron-emitting area,.all parts of which surface can be maintained at the same potential with respect to the anodes 4. Such a cathode is therefore what may be called an equi-potential cathode as distinguished from the-distributed potential cathode of the filamentary type customarily employed in audion devices.

In adapting such a device to use as an amplifier of telephonic currents, the terminels 8 of the platinum spiral 7 are connected to terminals of the battery 12 whose function it is to heat the spiral 7 to incandescence. The heating of this spiral causes a consequent incandescing of the cathode surfaces 6, making them thermionically active. In the diagrammatic arrangement ofFig. 2 one terminal 8 of the spiral 7 is connected to the secondary winding 13 of an input transformer 14 and serves therefore as an frequency characteristics asthe '1" ut currentimpressed on'the'winding13. t is thus seen that the arrangement. described r0 vides a thermionic translating device a ing the advantages of. an" 'equi-potential cathode with only three electrode elements, and without the necessityof cm loyin an additional heating'element for t e cat ode surface. Inasmuch as the heating element employed is used also as an input element and is not located between the cathode surface made thermionically active by heat radiation from said input electrode.

'2. In a thermionic translating device, a thermionically active cathode surface and a heated electrode adjacent said surface and serving the double purpose of an input electrode and a heater for said surface.

3. A thermionic translating device comprising an evacuated vessel, a cathode and an input electrode within said vessel and means outside. said vessel for incandescing said in'put'electrode.

4. A thermionic translating device comprising an evacuated vessel, an equi-potential cathode within said vessel, an input electrode also within said vessel and in close proximity to said cathode, and means outside said vessel for heating said input electrode and thereby rendering said cathode tllermionically active.

In witness whereof, I hereunto subscribe my name this 16th day of April, A. D. 1915.

ALEXANDER MOLEAN NICOLSON.

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