US2453753A - Method of manufacturing cathodes of electric discharge tubes - Google Patents
Method of manufacturing cathodes of electric discharge tubes Download PDFInfo
- 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
- discharge tubes
- 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
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J9/00—Apparatus 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
- H01J9/02—Manufacture of electrodes or electrode systems
- H01J9/04—Manufacture of electrodes or electrode systems of thermionic cathodes
- H01J9/042—Manufacture, activation of the emissive part
Definitions
- 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.
- cathodes which are manufactured otherwise, for example by application and dissociation of an alkaline earth carbonate
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
Landscapes
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Gas-Filled Discharge Tubes (AREA)
- Physical Vapour Deposition (AREA)
Applications Claiming Priority (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 (es) |
BE (1) | BE457760A (es) |
CH (1) | CH258433A (es) |
DE (1) | DE803919C (es) |
FR (1) | FR936339A (es) |
Cited By (1)
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)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
NL203172A (es) * | 1954-12-31 | |||
NL101810C (es) * | 1955-02-12 |
Citations (3)
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 |
-
0
- BE BE457760D patent/BE457760A/xx unknown
-
1946
- 1946-09-07 CH CH258433D patent/CH258433A/fr unknown
- 1946-11-27 FR FR936339D patent/FR936339A/fr not_active Expired
-
1947
- 1947-02-08 US US727303A patent/US2453753A/en not_active Expired - Lifetime
-
1948
- 1948-10-26 DE DEP19567A patent/DE803919C/de not_active Expired
Patent Citations (3)
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)
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 |
---|---|
FR936339A (fr) | 1948-07-16 |
DE803919C (de) | 1951-04-12 |
BE457760A (es) | |
CH258433A (fr) | 1948-11-30 |
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