US2236647A - Electronic tube - Google Patents

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US2236647A
US2236647A US584967A US58496732A US2236647A US 2236647 A US2236647 A US 2236647A US 584967 A US584967 A US 584967A US 58496732 A US58496732 A US 58496732A US 2236647 A US2236647 A US 2236647A
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cathode
caesium
tube
reaction
heating
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US584967A
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Oran T Mcilvaine
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J40/00—Photoelectric discharge tubes not involving the ionisation of a gas
    • H01J40/16—Photoelectric discharge tubes not involving the ionisation of a gas having photo- emissive cathode, e.g. alkaline photoelectric cell

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  • This invention relates to electronic tubes and has among its objects the provision or a device of this character wherein an increased vigor of electronic emission is secured per unit of energizing intensity, either heat or light as the case.
  • Fig. 1 is a perspective view partly in section of an unfinished tube of preferred form containing my improvements although it will be understood that the tube in question is capable of very great modifications in the shape, size, arrangement, number, position, and relation of its active elements;
  • Fig. 2 is a side elevation of a modified type of tube contain-r.
  • Fig. 3 is a section through a capsule of convenient shape together with its mounting.
  • cathode .l and anode 2 are carried by a press 3,;
  • the photoelectrode or cathode l consists of a metal plate of substantially semi-cylindrical shape having the slties tend to produce smoothly plated surfaces while high current densities tend to produce rough or mat surfaces, as is well understood by those skilled in the art.
  • the anode can be of the same substance or any other conductive material, copper or nickel being especially desirable.
  • the energizing substance consists of a caesium compound mixed with one or more elemental substances of a type which react therewith at a red or white heat, but not at a lower temperature, to reduce the caesium compound to metallic caesium with the generation of reaction-prodanode 2 substantially coinciding with its axis.
  • This plate is carried by an upright post I.
  • the cathode is preferably made, at least superficially, of silver and this preferably in a mat form. It may be a plate of pure silver, or it may equally well be a plate of base metal such as copper or nickel (or nickel-plated copper). electro-pla-ted externally with silver.
  • One well known method of accomplishing the, production of a mat surface r on an electio-plated article is by using a plating I bath of silver cyanide.
  • an important featureof my invention is the employment of such an elemental substance in combination with such a compound of caesium that the reaction shall only occur at a temperature above that necessary for the successful outgasslng otthe tubes and the metallic elements and'the energizing substance itself and this with the production of reactionproducts which are wholly solid, the ingredients also being of a non-hygroscopic nature.
  • the last-named limitat-lon essentially eliminates such metals as copper, gold platinum, silver and the iron-group metals, none of which have a strong affinity for oxygen.
  • Aluminumlles nearly on the border line, being unsatisfactory ln'that its reaction tends to begin. at too low a temperature and to proceed with undue vigor, although itcan' be employed in some cases if sufllclently diluted by restraining agents.
  • the caesium compound chosen, together with the reaction agent are mixed intimately together, preferably inthe proper molecular proportions, and introduced into the capsule I, which is made with a cavity for the purpose, the edges being closedby folding or spot-welding so as to hold the un reacted materials while allowing escape of volato a yellowish color, often streaked or discolored with brown. Carried further than this the next color produced is a brown, alsogiving good tilized caesium.
  • the various elements are introduced and sealed into the glass globe, the air exhausted by way of the pipe ll provided for the purpose, heat is applied in any suitable way to drive off the absorbed gases from the glass and from the tube elements, and a small amount of dry air (oxygen) is admitted, after which a unidirectional, high-tension current is passed be-- glass as the former permits the passage of more of the ultra violet rays than does the latter, and
  • Fig. 2 a three-element tube comtween the anode and the cathode, from an induction coil or other uni-directional source whereby all combined oxygen is removed from the anode, and the surface of the cathode is covered with oxidized silver. The gases are then exhausted with the employment of sufficient heat to outgas the glass and metal and energizing substance without however producing the re. action of such substance.
  • Sufllcient heat is then concentrated, upon the capsule to produce a reaction between the substances therein, which in the preferred case consist of caesium chromate andsiliwmthe reaction products consisting of metallic camium on the one hand and oxides of chromium and silicon on the other hand.
  • the heating may be effected by a burning glass or by a high-frequency inductionf-urnace, and requires a bright red heat. It occurs without undue vigor, although a slight intensification of redness is'visible at the instant of reaction.
  • a distinct advantage of the described composition in the case of a photo electron tube is that the glass walls are left unobscured. The tube and its contents are now al-' .lowed to cool.
  • the leading-in wires are next connected'to a suitable biasing battery in circuit with a microammeter and heat is applied. to the tube by surrounding it with an internally heated jacket or other suitable means.
  • a suitable biasing battery in circuit with a microammeter and heat is applied.
  • the tube by surrounding it with an internally heated jacket or other suitable means.
  • the purpose of the heating is two-fold: first, to volatilize the caesium which has become deposited elsewhere than 'upon the cathode, by which alone it is absorbed and retained, due to the oxidation of the silver which is supposed to react in some way with the caesium; a second object of the heating is to produce the described reaction between the metallic caesium and the silver oxide.
  • 'Ihis.re-' action apparently varies with the temperature and is signalized by a continuous change in color of the cathode, and by a constant vibration of the ammeter needle as the temperature of the tube is gradually raised.
  • the heating is stopped at the pointat which the cathode exhibits the prising a photo-electrode ii, an anode It, and a thermionic-electrode II (here consisting of an emissive element), the photo-electrode- II also constituting a grid.
  • the procedure hereabove described may be employed for energizing this tube, the grid being first plated with silver before assembling, and oxidised during the pumping operation. .Thisoxidation is confined entirely to the photo-electrode or grid by the electrical protection of the other elements. The remaining steps are similar. to those hereinbefore described.
  • light-beam will control passage of electrons from the thermionic-electrode It to the anode II in accordance with the intensity of the light-beam.
  • the process of activating a cathode of a photo-electric tube comprising the steps of electro-plating a coating of oxidizable material on the surface of a foundation structure and so controlling the electro-plating as to produce a mat surface on the coating, introducing said cathode and caesium reaction mixture into an envelope, exhausting said envelope, oxidizing the surface of said cathode in the presence of oxygen, liberating the caesium from said caesium-reaction mixture and depositing the same on the cathode, heating the cathode, and stopping the heating when the cathode shows a desired color efiect approximately between yellow and brown.
  • the process of activating a cathode of a photo-electric tube comprising the steps of coating a foundation member with silver, producing a mat silver surface on said coating by electroplating, introducing said cathode and a caesium reaction mixture into an envelope, exhausting said envelope, oxidizing the surface of the cathode in the presence of oxygen, liberating the caesium from said caesium reaction mixture and depositing the same on the cathode, heating the cathode withthe caesium deposit thereon, and stopping the heating when the'cathode' shows a color approximately between yellow and brown.
  • a photo-electric cathode comprising the steps of depositing a coating ofoxidizable material on the surface of a foundation structure and so controlling the'deposit as to produce a mat surface on the coating, oxidizing said mat surface, depositing on the oxidized surface a layer of light sensitive material, producing a chemical reaction between the oxidized surface and the light sensitive materia by applying heat to the cathode, and stopping the heating when the surface shows a color efiect approximately between yellow and brown,
  • a photo-electrio cathode comprising the steps of depositing a coating of oxidizable material on the surface of a foundation structure and so controlling the deposit as to produce a mat surface on the coatins. oxidizing said mat surface, depositing on the oxidized surface a layer of light sensitive material, heating the cathode, and stopping the heat-. ing when the surface shows a desired color effect.

Description

April 1, 1941. o. T. MCILVAINE 2,236,647
ELECTRONIC TUBE Original Fild Jan. 6, 1932 INVENTOR ATTORNEY Patented Apr. 1,1941
ELECTRONIC TUBE Oran T. Mcllvalne, Geneva, 11].
' Application January 6, 1932, Serial No. 584,967
' Renewed December 15, 1937 8 Claims. (01. 250-165) This invention relates to electronic tubes and has among its objects the provision or a device of this character wherein an increased vigor of electronic emission is secured per unit of energizing intensity, either heat or light as the case.
metric in its action; the provision of an improvedmethod of sensitizing or energizing such a tube; the provision of a new and improved composition of matter for effecting sensitization of such a tube; while further objects and advantages o; the invention will become apparent as the description proceeds.
In thedrawing accompanying and forming a part of this application Fig. 1 is a perspective view partly in section of an unfinished tube of preferred form containing my improvements although it will be understood that the tube in question is capable of very great modifications in the shape, size, arrangement, number, position, and relation of its active elements; Fig. 2 is a side elevation of a modified type of tube contain-r.
ing my improvements; and Fig. 3 is a section through a capsule of convenient shape together with its mounting.
In the particular embodiment here shown a.
cathode .l and anode 2 are carried by a press 3,;
sealed in the stem 6 of a glass-globe 5 and pro vided with leading-in wires 6. Any suitable or desirable kind of base can be employed.
In the embodiment shown in Fig. 1 the photoelectrode or cathode l consists of a metal plate of substantially semi-cylindrical shape having the slties tend to produce smoothly plated surfaces while high current densities tend to produce rough or mat surfaces, as is well understood by those skilled in the art. The anode can be of the same substance or any other conductive material, copper or nickel being especially desirable.
The energizing substance consists of a caesium compound mixed with one or more elemental substances of a type which react therewith at a red or white heat, but not at a lower temperature, to reduce the caesium compound to metallic caesium with the generation of reaction-prodanode 2 substantially coinciding with its axis.
This plate is carried by an upright post I. the
two electrodes being connected at their upper ends by a glass bridge 8 by which they are steadled, one of the parts also carrying .a tinyhollow metallic capsule 9 in which the energizing substanc or material is introduced. The cathode is preferably made, at least superficially, of silver and this preferably in a mat form. It may be a plate of pure silver, or it may equally well be a plate of base metal such as copper or nickel (or nickel-plated copper). electro-pla-ted externally with silver. One well known method of accomplishing the, production of a mat surface r on an electio-plated article is by using a plating I bath of silver cyanide. During the plating operation the current density is adjusted to the point where the desired character of surface is obtained on the plated article." Low current denucts which are wholly solid. The employment of caesium as an energizing agent is not uncommon, nor is the employment of caesium produced by-reaction, but 'a common procedure in the past has been to employs. reaction between caesium chloride and metallic calcium, thus producing calcium chloride and metallic caesium. Such mixture and reaction is unsatisfactory for two 'reasons: first, because caesium chloride tends readily to absorb water vapor whichit is'dimcult or impossible to remove completely, and because the reaction between the calcium and-the caesium chloride occurs at such low temperature as to render it impossible to heat the tube and its elements to a sufiicient temperature to remove the oocluded water vapor and other gases.
Accordingly an important featureof my invention is the employment of such an elemental substance in combination with such a compound of caesium that the reaction shall only occur at a temperature above that necessary for the successful outgasslng otthe tubes and the metallic elements and'the energizing substance itself and this with the production of reactionproducts which are wholly solid, the ingredients also being of a non-hygroscopic nature. These considerations clearly eliminate all the gaseous, liquid, and easily fusible elements, all alkaliand alkalineearth metals, all carbon, hydrogen, and halogen compounds, and leave in effect only oxygen-caeslum compounds for the subject, and the highermelting-point, oxygen-avid metals and metaloids as-the reactive agents. The last-named limitat-lon essentially eliminates such metals as copper, gold platinum, silver and the iron-group metals, none of which have a strong affinity for oxygen. Aluminumlles nearly on the border line, being unsatisfactory ln'that its reaction tends to begin. at too low a temperature and to proceed with undue vigor, although itcan' be employed in some cases if sufllclently diluted by restraining agents. Substances like boron, molybdenum,
and titanium are much better, but I prefer silicon above all; and for the caesium compound I prefer the chromate, inasmuch as it has a sufficiently high melting point, does not decompose or sublime while heating, is not hygroscopric, and produces, upon reaction with the substances mentioned, only solid non-volatile oxides. I donot limit myself to this one compound of caesium since other oxygen compounds thereof can be employed, such as the phosphate.
The preferred procedure is as -follows: the caesium compound chosen, together with the reaction agent are mixed intimately together, preferably inthe proper molecular proportions, and introduced into the capsule I, which is made with a cavity for the purpose, the edges being closedby folding or spot-welding so as to hold the un reacted materials while allowing escape of volato a yellowish color, often streaked or discolored with brown. Carried further than this the next color produced is a brown, alsogiving good tilized caesium. The various elements are introduced and sealed into the glass globe, the air exhausted by way of the pipe ll provided for the purpose, heat is applied in any suitable way to drive off the absorbed gases from the glass and from the tube elements, and a small amount of dry air (oxygen) is admitted, after which a unidirectional, high-tension current is passed be-- glass as the former permits the passage of more of the ultra violet rays than does the latter, and
I use either a vacuum or a gas-filling. Argon is good when gas is to be used, the pressures employed being up to a few mm. of mercury; 2/10 mm. pressure is very satisfactory, but either more or less canbe used.
As an example of a different arrangement I have shown in Fig. 2 a three-element tube comtween the anode and the cathode, from an induction coil or other uni-directional source whereby all combined oxygen is removed from the anode, and the surface of the cathode is covered with oxidized silver. The gases are then exhausted with the employment of sufficient heat to outgas the glass and metal and energizing substance without however producing the re. action of such substance.
Sufllcient heat is then concentrated, upon the capsule to produce a reaction between the substances therein, which in the preferred case consist of caesium chromate andsiliwmthe reaction products consisting of metallic camium on the one hand and oxides of chromium and silicon on the other hand. The heating may be effected by a burning glass or by a high-frequency inductionf-urnace, and requires a bright red heat. It occurs without undue vigor, although a slight intensification of redness is'visible at the instant of reaction. A distinct advantage of the described composition in the case of a photo electron tube is that the glass walls are left unobscured. The tube and its contents are now al-' .lowed to cool.
The leading-in wires are next connected'to a suitable biasing battery in circuit with a microammeter and heat is applied. to the tube by surrounding it with an internally heated jacket or other suitable means. As a result 'otthe chemical reaction above described the metallic caesium will have become-disseminated widely througtn out the tube and upon cooling will have condensed on all parts of the same. The purpose of the heating is two-fold: first, to volatilize the caesium which has become deposited elsewhere than 'upon the cathode, by which alone it is absorbed and retained, due to the oxidation of the silver which is supposed to react in some way with the caesium; a second object of the heating is to produce the described reaction between the metallic caesium and the silver oxide. 'Ihis.re-' actionapparently varies with the temperature and is signalized by a continuous change in color of the cathode, and by a constant vibration of the ammeter needle as the temperature of the tube is gradually raised. The heating is stopped at the pointat which the cathode exhibits the prising a photo-electrode ii, an anode It, and a thermionic-electrode II (here consisting of an emissive element), the photo-electrode- II also constituting a grid. The procedure hereabove described may be employed for energizing this tube, the grid being first plated with silver before assembling, and oxidised during the pumping operation. .Thisoxidation is confined entirely to the photo-electrode or grid by the electrical protection of the other elements. The remaining steps are similar. to those hereinbefore described. Such a tube, when subjected to. a
. light-beam, will control passage of electrons from the thermionic-electrode It to the anode II in accordance with the intensity of the light-beam.
A similar mode of operation could of course be obtained by connecting a separate thermioniceiectrode'plate to this grid either in the same or a different tube. I mention these modifications here to show the flexibility of my process, and how any element out of many ina tube can be exclusively energised. It will, be understood that the energizing substance can be diluted with other substances, either active or inactive, beneflcial or the reverse, without departing from my invention; for example a quantity of metallic chromium can be mixed with the other ingredients. Also the plating can be applied to the cathode only or to both electrodes, since'it is the oxidizingof the cathode surface and not its metallic nature which determines the selective adhesion of the caesium thereto. Other surfaces than silver are operative for the purpose, though silver due to the ease with which it is electroplated and the weakness of its aifinity for oxygen is particularly convenient. Accordingly I, do not limit myself to the forms of elements herein shown, nor the mode of connection thereof, nor the particular steps or materials described, except as the same are recited in my several claims which I desire may be construed broadly, each independent of limitations contained in other claims.
Having thus described my invention what I I maximum photo-electric'eifect; this corresponds rough surface activated by'caesium, the surface assess? 3. The art of manufacturing a photo-electric cathode comprising the steps of depositing a coating of oxidizable material on .the surface .of a foundation structure and so controlling the deposit-as to produce a mat surface on the coating, oxidizing said mat surface, depositing on the oxidized surface a layer, of light sensitive material,
heating the cathode, and stopping the heating when the surface shows a desired color effect approximately between yellow and brown.
4. The process of activating an electrode of a photo-electric tube comprising the steps of electro-plating acoating of oxidizable material on the surface of a foundation structure and so controlling the electro-plating as to produce a mat surface on the coating, introducing said electrode into an envelope,.oxidizing the mat surface of said electrode, depositing on the oxidized surface a layer of light sensitive material, producing a chemical reaction between the oxidized su1;- face and the light sensitive material by heating the electrode, and stopping the heating when the surface shows a desired color effect approximately between yellow and brown.
'5. The process of activating a cathode of a photo-electric tube comprising the steps of electro-plating a coating of oxidizable material on the surface of a foundation structure and so controlling the electro-plating as to produce a mat surface on the coating, introducing said cathode and caesium reaction mixture into an envelope, exhausting said envelope, oxidizing the surface of said cathode in the presence of oxygen, liberating the caesium from said caesium-reaction mixture and depositing the same on the cathode, heating the cathode, and stopping the heating when the cathode shows a desired color efiect approximately between yellow and brown.
6. The process of activating a cathode of a photo-electric tube comprising the steps of coating a foundation member with silver, producing a mat silver surface on said coating by electroplating, introducing said cathode and a caesium reaction mixture into an envelope, exhausting said envelope, oxidizing the surface of the cathode in the presence of oxygen, liberating the caesium from said caesium reaction mixture and depositing the same on the cathode, heating the cathode withthe caesium deposit thereon, and stopping the heating when the'cathode' shows a color approximately between yellow and brown.
7. The art of manufacturing a photo-electric cathode comprising the steps of depositing a coating ofoxidizable material on the surface of a foundation structure and so controlling the'deposit as to produce a mat surface on the coating, oxidizing said mat surface, depositing on the oxidized surface a layer of light sensitive material, producing a chemical reaction between the oxidized surface and the light sensitive materia by applying heat to the cathode, and stopping the heating when the surface shows a color efiect approximately between yellow and brown,
8. The process of manufacturing a photo-electrio cathode comprising the steps of depositing a coating of oxidizable material on the surface of a foundation structure and so controlling the deposit as to produce a mat surface on the coatins. oxidizing said mat surface, depositing on the oxidized surface a layer of light sensitive material, heating the cathode, and stopping the heat-. ing when the surface shows a desired color effect.
ORAN "1', McmvAmn.
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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2438897A (en) * 1943-08-26 1948-04-06 Bell Telephone Labor Inc Method of plating contact surfaces of magnetic reeds
US2462245A (en) * 1942-08-25 1949-02-22 Bell Telephone Labor Inc Space discharge device
US2627044A (en) * 1948-06-23 1953-01-27 Continental Electric Company Cathode for photocells
US2744837A (en) * 1951-06-01 1956-05-08 Rca Corp Photo-conductive targets for cathode ray devices
US3458408A (en) * 1962-11-16 1969-07-29 Monsanto Co Method for making an inductive heating element for zone refining apparatus
US3468806A (en) * 1965-12-06 1969-09-23 Westinghouse Electric Corp Alkali metal generator
US3468807A (en) * 1965-11-19 1969-09-23 Westinghouse Electric Corp Alkali metal generator

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2462245A (en) * 1942-08-25 1949-02-22 Bell Telephone Labor Inc Space discharge device
US2438897A (en) * 1943-08-26 1948-04-06 Bell Telephone Labor Inc Method of plating contact surfaces of magnetic reeds
US2627044A (en) * 1948-06-23 1953-01-27 Continental Electric Company Cathode for photocells
US2744837A (en) * 1951-06-01 1956-05-08 Rca Corp Photo-conductive targets for cathode ray devices
US3458408A (en) * 1962-11-16 1969-07-29 Monsanto Co Method for making an inductive heating element for zone refining apparatus
US3468807A (en) * 1965-11-19 1969-09-23 Westinghouse Electric Corp Alkali metal generator
US3468806A (en) * 1965-12-06 1969-09-23 Westinghouse Electric Corp Alkali metal generator

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