US2006560A

US2006560A - Electron discharge device

Info

Publication number: US2006560A
Application number: US423934A
Authority: US
Inventors: Warley L Parrott
Original assignee: Westinghouse Lamp Co
Current assignee: Westinghouse Lamp Co
Priority date: 1930-01-28
Filing date: 1930-01-28
Publication date: 1935-07-02
Anticipated expiration: 1952-07-02

Description

y 2, 1935. w. L. PARROTT 2,006,560

ELECTRON DISCHARGE DEVICE Filed Jan. 28, 1930 INVENTOR WL. PflRRorr.

ATTORN Y Patented July 2, 1935 ELECTRON DISCHARGE DEVICE Warley L. Parrott, East Orange, N. L, assignor to Westinghouse Lamp Company, a corporation of Pennsylvania Application January 28, 1930, Serial No. 423,934

3Claims.

This invention relates to electron discharge devices and more particularly relates to electron discharge devices incorporating an electron emitting hot cathode of the indirectly heated type,

5 the heater element of which is energized by the passage of an alternating electric current therethrough, and is more particularly an improvement in the invention set forth in copending applications Serial No. 292,116 filed July 12, 1928 and 372,331 filed June 20, 1929 by John W. Marden'and Ernst Anton Lederer, and application Serial No. 402,559 filed October 20, 1929 by Warley L. Parrott which applications are assigned to the same assignee as the present invention. The Warley L. Parrott of the above identified copending application is the same Warley L. Parrott of the present invention.

In copending applications Serial No. 292,116 and 372,331 is disclosed an electron discharge device comprised of an enclosing glass envelope,

an electron emitting cathode of the indirectly heated type, at least one concentrically disposed cooperating electrode, said cathode being comprised substantially ofa tubular metal sleeve member exteriorly coated with electron emitting material, refractory insulating end plug members, lead wires extending through the end plug members, and an interiorly disposed coil type heater-element electrically connected to the lead wires. To prevent deleterious electrical discharges from the lead wires to the cooperating electrodes of the device when the heater element is energized by alternating electric current a. dielectric shield member is interposed between the lead wires and the cooperating electrode; to eliminate deleterious electrical effects caused by thermionic electron emission from the incandescent heater element, the heater element is designed to operate at a temperature substantially below the temperature of active electron emission.

In copending application Serial No. 402,559 by Warley L. Parrott is disclosed an improvement over the two first identified Marden and Lederer applications, wherein the coil type heater element of the Marden and Lederer applications is replaced by a non-inductively wound coil type heater element, whereby a substantial elimination of the deleterious electrical efiectscaused by the induced electrical currents in the heretofore employed coil type filaments resulting in the socalled hum characteristic of the device is substantially eliminated, and a relatively closer and more accurate spacing of the elements of the device is thereby-obtained. The features of the prior art device of the. Marden and Lederer applications Serial No. 292,116 and Serial No. 372,331 of electrically shielding the lead wires of the heater element from the cooperating electrodes and of operating the heater element at a temperature substantially below the temperature of active electron emission are substantially retained in this copending Parrott application above identified.

It is one of the objects of the present invention tate the mounting of the elements in an elec- 15.

tron discharge device incorporating an electron emitting cathode of the indirectly heated type.

Another object of this invention is to improve and facilitate the manufacture of such devices.

Another object of this invention'isto provide an electron discharge device employing an electron emitting cathode of the indirectly heated type, the heater element of which is to be energized by alternating electric current, which device may be rapidly assembled and manufactured by modern radio tube machine assembly and manufacturing methods.

Other objects and advantages will become apparent as the invention is more fully disclosed.

In accordance with the above objects I have found that the dielectric shield member and the cathode sleeve end plug members of the above identified Marden and Lederer copending applications may be entirely dispensed with and that a small compact simplified assembly of elements supported on lead wires extending from a common stem provided, which may be rapidly and accurately assembled, and 'the device thus assembled may be subsequently put through the high speed mechanical manufacturing operationsof modern radio tube assembly with high manufacturing efliciency.

Before further disclosing the nature of my invention reference should be had to the accompanying drawing wherein,

Fig. 1 illustrates in enlarged detail a non-inductively wound cathode heater element, such as is set forth and claimed in copending application Serial No. 402,559 above identified;

Fig. 2 is a view partly in cross-section of an electrode assembly of an electron discharge device mounted in accordance with the present invention;

Fig. 3 is a top view of the electrode assembly illustrating one feature of the present invention: and

Fig. 4 is a side elevational view of an electron discharge device with the enclosing glass envelope broken away to show the assembly of elemen therein.

Referring to Fig. 1 the non-inductively wound cathode heater element is comprised of a noninductive coil type filamentary conductor I, comprised of a refractory metal such as tungsten, and a refractory core member 2 which is comprised substantially of electrically insulating material such as aluminium oxide, magnesium silicate, magnesium oxide and the like refractory materials, the exterior surface of the assembly being coated with refractory electrically insulating material 3, in accordance with the practice set forth in my copending application Serial No. 402,559 above identified.

The process of assembling this heater unit briefly stated comprises first shaping the twin coil heater element about a mandrel of the desired diameter replacing the mandrel with the refractory core member, annealing the shaped twin coil helix in hydrogen to about 1400 C. to set the coil turns on the core member, exteriorly coating the assembly with refractory insulating materials such as aluminium oxide, talc, magnesium silicate, and the like which are non-deleterious with respect to the heater element wire and again baking the assembly to consolidate and cement the exterior coating of refractory material to the surface of the coiled heater member I and to the refractory core member 2.

By the practice of this invention a rigid cathode heater assembly is obtained wnich is substantially self supporting when

terminals

4 and 5 are electrically connected, as by spot welding to leading in support wires Ii and 1 in Fig. 2.

In accordance with the present invention this cathode heater assembly is first inserted in a metal tubular sleeve member 8 having a diameter slightly greater than the overall diameter of the heater assembly, and a length appreciably greater than the overall length of the same, the exterior surface of the sleeve member having been previously coated in any desirable manner at least in part with thermionically active material such as admixtures of alkaline earth metal compounds which may be thermally decomposed into alkaline earth metal oxides when desired.

The

terminals

4 and 5 of the heater element 1 are then electrically united to the leading-in support wires 6 and I (Fig. 2) of the mount assembly of the electrical device incorporating the same.

The mount assembly typical of the present invention is shown in Fig. 2 and is substantially that which is employed in radio receiving tubes known in the trade as UY 227 tube. This type tube comprises essentially in a centrally disposed electron emitting cathode of the indirectly heated type the heater element of which is energized by alternating electric current, such as is shown in Fig. 1, and concentrically arranged control and anode electrodes, the latter of which is preferably comprised of perforated or meshed metal materials which have high heat radiating and low heat reflecting capacities, for the purpose of preventing the heating up of the internally situated grid or control electrode to such temperatures at which the electrode itself would tend to emit thermionic electron emission.

The method of mounting the electrodes in accordance with the practice of the present invention is substantially as follows: The non-inductive heater element prepared in accordance with the teachings of United States Patents No. 1,865,422 issued July 5, 1932 and No. 1,972,162 issued September 4, 1934, is first mounted in the usual manner on the filament lead wires 5 and I. The cathode sleeve member is then placed in position therearound and electrically connected by means of metal strip 28 to lead wire 29.

The grid (I1) and anode (I6) electrodes are next placed in position and electrically united to support wires 9 and III as by welding thereto. An electrically insulating spacer member 22 which may be comprised in the present example of sheet mica of approximately 10 m.m. width by 20 mm. length, having five properly spaced holes is then threaded down over the end of the two main support wires 9 and III, the grid posts l8 and I9 and the cathode sleeve member 8, in a manner as indicated in Fig. 2.

The mica spacer member is shown in more particularity in Fig. 3, which is a top view looking down on the spacer member in position as in Fig.

2. It is preferable to rigidly engage the spacer member to support wires 9 and In which is accomplished in the present illustration by means of

eyelets

23 and 24 the collar of which eyelet is integral with the spacer member 22 and the sleeve of which is rigidly united to the support wires 9 and ID in any convenient manner as by frictional engagement or by spot welding the sleeve thereto. 30

The final stp of the mounting operation consists in the closing up or pinching together of the open end of the cathode sleeve member 8 projecting above the spacer member 22 through the central opening 25 in the manner shown in Fig. 3. This pinching together serves a two fold purpose, first in serving to position the sleeve member in the assembly and restrain the same from relative displacement and secondly, the closure of the end of the sleeve member substantially prevents the escape of heat energy and prevents deleterious electrical discharge from the incandescent alternating current energized heater element and the cooperating electrodes of the device as a result of the differences or variations in electrical potentials therebetween.

In accordance with the teachings of copend ing application Serial No. 372,331, the operating temperature of the heater element is maintained substantially below the temperature of active thermionic emission either from the heater element wire itself or from the associated refractory insulating materials.

The remaining elements of the device are substantially as heretofore disclosed by the art in that the lead support wires 6, I, 9, l0 and 29 are electrically connected through press II to exterior

electrical conductors

25, 21, l2, l3 and 30 in the usual manner by dumet seals l4. Means are provided for cleaning up residual gases such as by getter l5, mounted on getter helmet 2i and supported by means of support wire 20 integral with main support wire ill in a position such that the vaporized getter material does not deposit across press II to cause deleterious electrical leakage.

The compact completed assembly comprising the enclosing glass envelope 3|, a base member 32, the cathode, cooperating electrodes, and the like elements of the device may be noted in Fig. 4 wherein a 227 type tube constructed in accordance with the present invention is shown. The enclosing glass envelope is broken away.

It may be noted that the compactness and simplicity of the assembly as compared to prior with electron emitting material and an interiorly' devices is marked. This results in minimum costs of production with a maximum conservation of time and labor. The device may be readily manufactured by high speed sealing in and exhaust methods and the resultant manufacturing efficiency is relatively high.

A 227 receiving tube device constructed in accordance with the present invention eliminating the dielectric shield members and the cathode end plug members of the prior devices, has a hum value resulting from deleterious electrical leakages of less than one millivolt as compared to Z to 3 millivolts of the prior art devices, and a maximum heating up time of cathode not to exceed substantially 7 to 8 seconds as compared to 14 to 20 seconds of the prior artdevices. Moreover the method of rigid assembly and positioning of elements results in a substantially 11onmicrophonic structure, and a device having highly uniform electrical characteristics.

Having broadly and specifically disclosed the nature of my invention it is apparent that there may be many variations and departures made of the specific embodiment herein disclosed, and such variations and departures are anticipated as may fall within the scope of the following claims.

What is claimed is:

1. An electron discharge device comprising an enclosing glass envelope, cathode, grid and anode electrodes supported from a common press and maintained in spaced relationship by means of a spacer member secured to the support wires of said press, lead Wires extending through said press and electrically connected to said electrodes, said anode electrode comprising a meshed plate material of relatively high heat radiating capacity and relatively low heat reflecting capacity', and said cathode electrode comprising a tubular metal sleeve member exteriorly coated positioned non-inductively wound coil type heater element having the terminals extending from one end thereof, said sleeve member being substantially sealed at the end remote from the common press of the device and supported thereby by means of said spacer member secured to the support wires of the said common press.

2. In an electron discharge device the combination of an electron emitting cathode of the indirectly heated type, the heater element of which. is energized by the passage of an electric current therethrough, a meshed plate anode electrode and a control electrode, supported from a common press concentric to said cathode electrode, the heater element of said cathode being comprised of a substantially noninductive coil type refractory metal filament operating at a temperature substantially below the temperature of active electron emission, the terminals of said coil extending from one end thereof, an electrically insulating spacer member, and the electron emitting element of said cathode being comprised of a tubular metal sleeve member substantially closed at one end and supported thereby by means of said electrically insulating spacer member fixed in position with respect to said anode and control electrodes at a point remote from the common press of the device.

3. A radio tube includingan anode plate, a grid, a tubular cathode element, together with an insulating plate at the top of said anode plate positively engaging all three elements to maintain them in proper spaced relation with respect to each other, the tubular cathode element passing through an opening in the top insulating plate and having a projecting end crimped to anchor it to said insulating plate.

"WARLEY L.