US1738957A - Photo-electric tube - Google Patents

Description

Dec. 10, 1929.

H. E. METCALF PHOTO ELECTRIC TUBE Filed April 16 1925 2 Sheets-Sheet l IN VEN TOR. HERBERT E. METCALFI ATTORNEYS.

1929. H. E. METCALF PHOTO ELECTRIC TUBE Filed A ril'la, 2 Sheets-Sheet 2 //\J Wu]. Z

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HERBERT E. METC'ALF'. BY

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tread This invention. relates to apparatus iior use in Wireless Wl communications and cornniercial use -for rectification, amplihlca gencrat n oi either low high k may oeil y The olo i ct or the invention is to produce at character employing a vacuum tuhe or i sell having a iihn, layer or surface ve tile material, Whicln under the action oi? light or enternal heat, will cause an emission to the anode so to inaction in the desired manner Without employing the usual hot electrode inside the tuhe or vessel.

A further ohject ol' the invention is to tacilitate the inanutacture ot a rectifier, anr plilier or oscillator at the type mentioned in carrying out these ohjects, ll employ an evacuated vessel oi? glass, quarts, or other suitahle material, which has contained therein a cathode in the term at a hint, layer or surlace ot a volatile material, such as these metals helonging' to the sodium-potassium group connected to the outside by a suitable connection. This film, layer or surface is deposited by means of condensation. There may he contained therein also an anode or collecting device. The state of the interior of the evacuated vessel may he a complete vacuum, or any intermediate stage of gaseous content, or it may be filled after pumping with a gas of the helium group in order to prevent the breaking down of the cathode.

This device is made so as to function in ractically the same manner as the wellnown two electrode vacuum tube, except that it shall not contain any filament or hot" electrode inside the tube. The emission from the active and sensitive film, la or or surface is caused either by the action 0 light fallin upon the cathode or the action of heat applie by a heater. external to the entire tube. It has been found that emission ma be obtained from the cathode to the ano e by the use of either light or heat, and that the emission may be controlled by an intermediate electrode, if desired, when the anode is kept at a positive potential. It has furthermore beeri found that in the manufacture of such a tube special care should be'taken to re'vent the contamination of the anode by t e subtlun tiled hprll l t lilo. tillltitli'ttt.

stance which is nsedas cathode in order that it inaction properly, and the present applica tiondiscloses a method whereby such con tainination eliminated.

lln the pre'lerred method of manufacture, the volatile materials, such as those metals oil the sodiumopotassirun group, are placed on the anode helore assernhly into the com" plete tuhe, and "when said anode is heated. alter asseinhly into the tuhe, the volatile mas terials thereon are vaporised and deposited. hy condensation on the Walls oi the tube or on a nearhy receptacle tor the purpose at act-'- inp later as a cathode. 'lhe cathode material is termed upon the anode and hy means oil heat applied to the anode, such material is evaporated tol'ornrthe cathode. in this manner the anode is tread train contamination hy the cathode material and at the same time the cathode is termed in the shape at a film deposited over the entire inner ,Wall oil the tuhe or other hase. lln order that the place Where connection is made through the -when-it is set, into operation only in the action' of light, a ortion ofthe walls 0 the tube may be cleans of cathode material by means of heat, thus giving. a ,window whereby light may be admitted to the interior of the tube.

In case it is desired that the tube be operated by heatonly, such awindow is not necessary and the entire tube may he laced inside a heating element which is entirely independent of any electrical connection to the tube itself. v

In the accompanying drawings- Fig. 1 shows a diagrammatic'view of the. composite filament before the same'is inserted in the vessel or tube.

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Fig. 2 shows a diagrammatic view of the composite filament in place within the vessel -or tube and before the same has been heated tube or vessel after the volatile material has been discharged from the composite filament and deposited upon the walls of the vessel.

Fig. 5 shows a diagrammatic view of a modified form wherein a cylindrical member is placed around the composite filament.

- ig. 6- shows a view of a similar form after the composite filament has been heated to cause deposition of the volatile substance upon the cylinder.

' 7 shows a modified arrangement wherein the volatile material is placed in a reservoir at one end of the vessel and heated by external means to cause deposition of the material u on the walls of the vessel.

Fig. 8 s ows a diagrammatic view of a device embodying my invention and employing an intermediate member so as to function after-the fashion of the well known threeelectrode vacuum tube.

I Referring in detail to Fig. 1 of the accompanying drawings, I show a non-volatile wire 7 upon which there has been deposited a volatile active substance 8 which is shown merely for clearness in the drawing as being in the form of nodules. It may also'be in the form of a smooth coating. Both ends of this non-volatile wire are brought out with two terminals 1 and 2. This portion is sealed into 'a vessel 10, as shown in Fig. 2. There is a connection 4 on the wall of the tube which will become the means for electrical connection to the cathode surface when it is later formed.

A battery 11 is then attached to the terminals 1 and 2 of the non-volatile wire, as shown in Fig. 3, and said non-volatile wire 7 is then heated by the passage of a current. This heat vaporizes the volatile portion 8 of the wire and such volatile material is deposited in the form of a film 5 over the inside .walls of the tube, as shown in Fig. 4, thereby forming the cathode. The cathode is then connected through the medium-of connection 4. This leaves the non-volatile ortion of the entire assembly in 'the center ree of volatile material, as indicated at 6. The two ends 1 and 2 are then joined together to make a third connection 3 which then becomes the anode lead. Referring further to Figure 4, it may be seen that the tube is complete, having a connection 4 to the active cathode surface 5,

- and" a non-volatile wire 6. in the center of the evacuated vessel forming the anode. The surfaces which are not shown covered by cathode material have been cleaned of same by heat from an outside source or by the use of shields during vaporization.

Fig. 5 shows a slightly different type where a metal base is used, whereon the active material is deposited instead of the walls of the vessel 10. This metal base is indicated at 9, being preferably in the form of a cylinder. The procedure for depositing cathode material thereon is exactly the same as already described. The anode 7 containing cathode material 8 is heated through the medium of the battery '11, as shown in Fig. 6. The active material 8 becoming vaporized is thereupon deposited upon the metal base 9 in the form of an active film or surface 5, leaving the center anode 6 free and uncontaminated from cathode material.

Fig. 7 shows a device of this sort which is made by the vaporization of active material from an outside well 8. This active material may be vaporized by the application of external heat and is deposited by condensation in the form of a film 5 on the walls of a vessel llO, the cathode connection being made at 4.

However, in making a device of this sort it is difiicult to prevent the anode 6 from being contaminated by condensed cathode material, so by making the anode 6 in the form of a loop or continuous wire, both ends being brought to the outside, the current from the attery 11 may be passed through the anode terminals 1 and 2, heating the anode 6, thereby evaporating from it and cleansing it of all cathode contamination.

Fig. 8 discloses a method whereby an intermediate member may be introduced into this evacuated vessel 10. Either or both the member 15 and anode 6 may be used to deposit the volatile active material. However, it is important that a current be passed through both the anode and the intermediate member 6 and 15, so that they may be efl'ectively cleansed of contamination by cathode material. For this purpose I show batteries 11 and 13. The evacuated vessel in this case would act practically in the same manner as the well known three-electrode vacuum tube.

Various changes in the construction and arrangement of the several parts herein shown and described may be employed without departing from the spirit of my invention as disclosed in the ap ended claim.

Having thus descri (I my invention what I claim and desire to secure by Letters Fatent 1s:

In a two-electrode vacuum tube having an evacuated vessel and double terminal anode, the latter having deposited thereon a volatile material sensitive to the action of light, the step of heating the anode to cause the volatile material to be vaporized and deposited in the form of a sensitive film upon the inner wall of the vessel, whereby to form a light sensitive cathode.

HERBERT E. METCALF.

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