US2453753A - Method of manufacturing cathodes of electric discharge tubes - Google Patents

Method of manufacturing cathodes of electric discharge tubes Download PDF

Info

Publication number
US2453753A
US2453753A US727303A US72730347A US2453753A US 2453753 A US2453753 A US 2453753A US 727303 A US727303 A US 727303A US 72730347 A US72730347 A US 72730347A US 2453753 A US2453753 A US 2453753A
Authority
US
United States
Prior art keywords
cathode
electric discharge
tube
cathodes
film
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US727303A
Inventor
Loosjes Robert
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hartford National Bank and Trust Co
Original Assignee
Hartford National Bank and Trust Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to BE258433X priority Critical
Application filed by Hartford National Bank and Trust Co filed Critical Hartford National Bank and Trust Co
Application granted granted Critical
Publication of US2453753A publication Critical patent/US2453753A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Classifications

    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01JELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J9/00Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
    • H01J9/02Manufacture of electrodes or electrode systems
    • H01J9/04Manufacture of electrodes or electrode systems of thermionic cathodes
    • H01J9/042Manufacture, activation of the emissive part

Description

Patented Nov. 16,1948
, Marne!) oFMANUFAoTURING cArHoDEs j or ELECTRIC DISCHARGE TUBES] V .Robert Loosjes, Eindhoven, Netherlands, assig'nor to Hartford National Bank and, Trust Com:
- "pany, Hartford,- (;onn., as trustee No Drawing. Application February 8,1947, Se-
rial No. 727,303. In Belgium November 4, 1944 Section 1, Public Law .690, August 1 v Patent expires November 4, 1964 3 Claims.
In the manufacture of cathodes for electric discharge tubes, it is sometimes desirable to incorporate a method which permits of the cathode being manufactured outside the tube itself and of being exposed to the atmosphere for some time. This necessity particularly occurs in the case of cathodes that are manufactured, for example by the well-known azide-treatment as described in the Netherlandish Specification 19,215, more generally speaking in those methods, in which an alkaline earth metal is precipitated from the vapour phase, since in such cases there is the risk that the barium which evaporates from the azide or other compound or mixture would become deposited not only on the cathode but also on other areas or parts inside the tube and causes undue emission phenomena from those areas or parts, and in certain cases even cause short circuits. Also in the case of cathodes which are manufactured otherwise, for example by application and dissociation of an alkaline earth carbonate, it is important to incorporate a method in which the cathode is first manufactured in a separate space, in order to avoid the generation of large quantities of carbonic acid in the tube which must then be removed.
Th object of the present invention is to provide a method of manufacturing a cathode of an electric discharge tube, which consists in that an oxide cathode manufactured in any way in a separate space is coated with a copper, silver or gold film, is then removed from this space and finally incorporated in the actual tube, where the protecting outer layer is then vclatilized from the cathodes by heat.
This method provides a means of keeping the cathode for any length of time, for example in air, and in such cases it is not essential that the cathode should be manufactured inside of the tube in which it is to be used ultimately. It is desirable to use a protective layer which has no detrimental effect during volatilisation. Thus, for example, the protective metal films made of copper, silver or gold have advantages over the well-known layers made of a hydrocarbon, such as parafiin, polystyrene and similar substances, because the latter substances produce harmful gases during volatilisation, whereas the metals according to the invention practically have no detrimental effect. It is in many cases, even advantageous when a grid or an anode is coated with a copper, silver or gold film. The coating with copper, silver or gold can be readily effected by volatilization from a Wire Which is arranged in the proximity of the cathode. The protective film need only have a thickness of some few microns.
In order that the invention may be clearly understood and readily carried into effect, it will now be set out'more fully with reference to two embodiments, given by way of example, in which methods according to the invention are described in detail.
Barium-azide is heated and dissociated in a separate, exhausted space; next barium is volatilized and the vapour produced deposited on a core body, the surface of which is constituted by nickel oxide or copper oxide; an emissive layer of barium oxide is then formed by heat. Next, the barium oxide has a protective copper film applied to it by volatilization in the same space and the cathode, after being kept in the air for any length of time, is incorporated in the actual tube, the protective copper film being removed by volatilization.
In an alternative embodiment of the method according to the invention, a cathode core body is coated in known manner with a layer of a mixture of bariumand strontiumcarbonate; these carbonates are then dissociated, the carhome acid formed is pumped off and the alkaline earth oxide left on the core is coated with a silver film. The cathode is then removed from this space and after being kept in air for any length of time, is incorporated in the actual tube, the silver film being removed by volatilization.
What I claim is:
1. A method of manufacturing a cathode of an electric discharge tube, which comprises treating a cathode core with an alkaline earth material in an evacuated space to provide a layer of an alkaline earth metal oxide, coverin the layer with a film of a metal selected from the group consisting of copper, silver, and gold, removing the cathode thus formed from that space and disposing the cathode in the tube in which it is to be used, sealing the tube and removing the metal film from the cathode by volatilization of the metal.
2. A method of manufacturing a cathode of an electric discharge tube as claimed in claim 1, including heating and dissociating an alkaline earth metal azide in an exhausted space separate from the tube in which the cathode is to be used, depositing the alkaline earth metal vapour thus produced on a cathode core having a surface of nickel oxide or copper oxide, and then coating this body with a metal selected from the group consisting of copper, silver and. gold film, then removing the cathode thus obtained from the 3 said space and housing it in the actual tube where it is to be used, and then volatilizing the metal film.
3. A method of manufacturing a cathode of an electric discharge tube as claimed in claim 1, including the step of applying an alkaline earth carbonate to a cathode core body, then heating and dissociating the carbonate in an exhausted space separate from the tube in which the oathode is to be used, coating thealkaline earth oxide with a film of metal selected from the group-consisting of silver, copper and gold, removing the body thus obtained from the said space and housing it in the actual tube, and then removing the protective metal film by volatilization.
ROBERT LOOSJES.
REFERENCES CITED The following references-are of record in the file of this patent:
UNITED STATES PATENTS Number Name Date 1,936,334 Miesse Nov. 21, 1933 1,936,419 Asao et a1 Nov. 21, 1933 FOREIGN PATENTS Number Country Date 255,090 Great Britain June 9, 1927
US727303A 1944-11-04 1947-02-08 Method of manufacturing cathodes of electric discharge tubes Expired - Lifetime US2453753A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
BE258433X 1944-11-04

Publications (1)

Publication Number Publication Date
US2453753A true US2453753A (en) 1948-11-16

Family

ID=3866700

Family Applications (1)

Application Number Title Priority Date Filing Date
US727303A Expired - Lifetime US2453753A (en) 1944-11-04 1947-02-08 Method of manufacturing cathodes of electric discharge tubes

Country Status (5)

Country Link
US (1) US2453753A (en)
BE (1) BE457760A (en)
CH (1) CH258433A (en)
DE (1) DE803919C (en)
FR (1) FR936339A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2750528A (en) * 1955-02-17 1956-06-12 Sylvania Electric Prod Electronic tube element protective coating

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL203172A (en) * 1954-12-31
NL101810C (en) * 1955-02-12

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB255090A (en) * 1925-07-13 1927-06-09 Gen Electric Improvements in or relating to methods of manufacturing electrodes for electron discharge devices
US1936419A (en) * 1930-06-03 1933-11-21 Gen Electric Photo-electric tube
US1936334A (en) * 1929-01-31 1933-11-21 Gen Scientific Corp Electrode

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB255090A (en) * 1925-07-13 1927-06-09 Gen Electric Improvements in or relating to methods of manufacturing electrodes for electron discharge devices
US1936334A (en) * 1929-01-31 1933-11-21 Gen Scientific Corp Electrode
US1936419A (en) * 1930-06-03 1933-11-21 Gen Electric Photo-electric tube

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2750528A (en) * 1955-02-17 1956-06-12 Sylvania Electric Prod Electronic tube element protective coating

Also Published As

Publication number Publication date
CH258433A (en) 1948-11-30
DE803919C (en) 1951-04-12
FR936339A (en) 1948-07-16
BE457760A (en)

Similar Documents

Publication Publication Date Title
US2842706A (en) Cold cathode vacuum tube
US2041802A (en) Electron emitter
US3563797A (en) Method of making air stable cathode for discharge device
US2453753A (en) Method of manufacturing cathodes of electric discharge tubes
US2887413A (en) Thermionic cathode for electron tubes and method for producing same
US2159774A (en) Secondary electron emitter and method of making it
US2620287A (en) Secondary-electron-emitting surface
US2700626A (en) Secondary electron emissive electrodes
US2154131A (en) Getter
US3121182A (en) Cathode ray tube, getter, and method of gettering
US2185410A (en) Metal compositions
US3666533A (en) Deposition of polymeric coatings utilizing electrical excitation
US2464874A (en) Method of manufacturing an oxide cathode for an electric discharge tube, and discharge tube made according thereto
US3553521A (en) Indirectly heated cathode for an electron discharge tube with an insulated heating element
US2798010A (en) Method of manufacturing indirectly heated cathodes
US1921066A (en) Cathode for electron discharge devices and method of making the same
US2585534A (en) Secondary electron emissive electrode and its method of making
US2112975A (en) Photoelectric tube
US2864024A (en) Glow-discharge tube
US2464702A (en) Process for manufacturing cathodes for electron discharge tubes
US1837746A (en) Photo-electric tube
US3666547A (en) Photo-cathodes for electronic discharge tubes
US2554257A (en) Protection of phosphors from attack by alkali vapors
US2924737A (en) Glow discharge tube
US2488727A (en) Electrode for electric discharge devices