US3054014A - Electrode for high-pressure electric discharge lamps - Google Patents

Electrode for high-pressure electric discharge lamps Download PDF

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Publication number
US3054014A
US3054014A US39408A US3940860A US3054014A US 3054014 A US3054014 A US 3054014A US 39408 A US39408 A US 39408A US 3940860 A US3940860 A US 3940860A US 3054014 A US3054014 A US 3054014A
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United States
Prior art keywords
rod
crystals
thorium oxide
electrode
cathode
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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
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US39408A
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English (en)
Inventor
Gemsa Johannes
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.)
Osram GmbH
Original Assignee
Patent Treuhand Gesellschaft fuer Elektrische Gluehlampen mbH
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Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00—Gas-discharge or vapour-discharge lamps
    • H01J61/02—Details
    • H01J61/04—Electrodes; Screens; Shields
    • H01J61/06—Main electrodes
    • H01J61/073—Main electrodes for high-pressure discharge lamps
    • H01J61/0735—Main electrodes for high-pressure discharge lamps characterised by the material of the electrode

Definitions

  • This invention relates to electrodes for high-pressure electric discharge lamps comprising a sealed envelope containing an ionizable gaseous or vapor atmosphere. These electrodes are produced by pressing a mixture of tungsten powder and small additions-of thorium oxide to slug form, sintring the slug form to provide a strongly coherent body, swaging and sometimes drawing said'body to rod form having a diameter of, for instance, aboutone or several millimeters. Said rods are divided into portions of suitable length, and one end of each rod portion is tapered.
  • such a thoriumoxide-containing tungsten rod is, usually, inserted in a metallic block or cylinder of, for instance, sintered tungsten or it is enclosed or supported by other metallic parts.
  • Another'objectof the-present invention is'the provision of an electrode for a high-pressure electric discharge lamp so designed as to guarantee always silent burning of the discharge arcand have also a sufficient long life.
  • an electrode composed of a solid massive rod having a tapered tip portion and consisting of tungsten and a small addition of thorium oxide, said rod comprising interlocking crystals elongated longitudinally throughout said rod, the length of said crystals amounting at least to several millimeters, the width of said crystals amounting at least to several tenths of millimeters, said rod comprising beside said crystals a plurality of particles minute compared with said crystals, consisting of said thorium oxide and 'being distributed uniformly throughout the whole volume of said rod and enclosed tightly within said coarse crystals.
  • process steps for manufacturing the electrodes whichprocess steps include an annealing procedure for the rod.
  • the present invention represents a surprise because, as is well known, for thorium oxide-containing tungsten cathodes of electronic discharge tubes a micro-crystalline structure is required in the grain boundaries of which the activating material is concentrated. Such a structure only guarantees in electronic discharge tube cathodes for a longer time a stability between the number of activated atoms passing out from the surface per unit of time and those atoms supplied to the surface in the same time.
  • any impoverishment in respectof thorium oxide by diffusion of the thorium oxide particles 'in the electrode and evaporation toward outside is restrained so much that after a longer burning period a loss in thorium oxide may be observed in a very narrow edge zone of the electrode point only.
  • An impoverishment of "the electrodes in respect of thorium oxide is, obviously, restrained by means of a tight enclosure and uniform dis tribution of the particles in the coarse crystals.
  • FIG. 1 shows an etched ground section of a thorium oxide-containing tungsten rod in a preliminary state of cathode manufacture in about tenfold enlargement
  • FIG. 2 shows an etched ground section of a finished cathode according to the present invention in about tenfold enlargement.
  • FIG. 3 shows a cutout of an etched ground section-of a cathode without any features of the invention after 152 operating hours which cutout is taken from a range somewhat remote from the point in about two hundredfold enlargement.
  • FIG. 4 shows a cutout in about seventy five-fold enlargement of a non-etched longitudinal groundsection "of a cathode according to the invention after 900 operating hours.
  • FIG. 5 shows a cutout in about seventy five-fold enlargement of a non-etched longitudinal ground section of a cathode without any features of the invention after 152 operating hours.
  • FIG. 6 shows a cutout in about two hundredfold enlargement from the cathode shown'in FIG. 4 which cutout is taken from a range somewhat rem'ote'from the point.
  • FIG. 7 shows a corresponding cutoutfrom the'cathode shown in FIG. 5.
  • All the tungsten rods shown in the drawings have a thorium-oxide content of about 5% by weight.
  • Thorium oxide-containing tungsten rods may be manufactured in such a manner that some thorium oxide powder or powdered metallic thorium is admixed to the tungsten powder and that this mixture of powders is pressed, sintered, swaged and, if desired, drawn according to well-known methods.
  • a. thorium compound in dis-solved form already to the tungstic acid the starting material for the manufacture of tungsten.
  • the swaged rod represented in FIG. 1 shows clearly perceivable crystals 1 deformed by the swaging procedure and more or less elongated in the direction of the rod axis.
  • the proportionately short rod is tapered for the appendage of an arc discharge at 2.
  • FIG. 2 shows the finished cathode according to the invention.
  • the number of reference 3 designates the partly represented cathode body of sintered tungsten into which the thorium oxide-containing tungsten rod 4 is inserted. The latter was annealed for about 15 minutes in a high-temperature furnace provided with a tube in which the tungsten is annealed in a hydrogen-nitrogen stream at 2800" C. Thereby, the swaged structure shown in FIG. 1 changed by means of complete recrystallization into a coarse crystalline structure with interlocking Crystals 5 elongated longitudinally throughout rod 4, the length of crystals 5 amounting at least to several millimeters, the Width of crystals 5 amounting at least to several tenths of millimeters.
  • a plurality of particles 6, minute compared with crystals 5, consisting of said thorium oxide, is distributed uniformly throughout the Whole volume of rod 4 and enclosed tightly within the coarse crystals 5.
  • FIG. 3 shows the structure of a cathode of a lamp burning with unsilent are. It shows small polygonal crystallites 7 only somewhat elongated in longitudinal direction which meet with plain grain boundaries. A bad operating behavior was observed also with electrodes having other fine crystalline structures in which the fine crystals were elongated in axial direction.
  • FIG. 6 represents a very much enlarged cutout of a cathode according to the present invention and shows still better than FIG. 2 how the thorium oxide particles 6 penetrate in uniform distribution the entire coarse crystalline structure. There the particles 6 have a round shape. But they may also be elongated in longitudinal direction of the rod.
  • FIG. 7 shows a cathode without any features of the invention; there the thorium oxide is embedded in the grain boundaries only of the crystallites 7 in a lineor punctiform manner as it may be seen if compared with FIG. 3.
  • the thorium oxide particles are found not only in the grain boundaries but project also into the fine crystals elongated in axial direction. It is quite clear that the thorium oxide particles 10 in both these cases under the effect of the discharge are escape in a quicker and more violent manner from the metal than in case of an enclosure within the coarse crystals 5.
  • the numerous, interconnected grain boundaries of the crystallites 7 form, so to say, a network-type structure of smallest capillaries leading to the surface whereby a quick impoverishment in respect of thorium oxide is supported on the cathode.
  • the thorium oxide particles 10 will vaporize the quickest at this place.
  • FIG. 5 it follows therefrom a quick thorium oxide loss on the cathode point and the formation of pores which are formed in the soft tungsten, partly heatedup on certain places to the melting point, by means of the vaporizing thorium oxide.
  • An electrode for a high-pressure electric discharge lamp composed of a solid massive rod having a tapered tip portion and consisting of tungsten and a small addition of thorium oxide, said rod comprising interlocking crystals elongated longitudinally throughout said rod, the length of said crystals amounting at least to several millimeters, the Width of said crystals amounting at least to several tenths of millimeters, said rod comprising besides said crystals, a plurality of particles minute compared with said crystals, consisting of said thorium oxide and being distributed uniformly throughout the whole Volume of said rod and enclosed tightly Within said coarse crystals.

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  • Discharge Lamp (AREA)
US39408A 1959-07-08 1960-06-28 Electrode for high-pressure electric discharge lamps Expired - Lifetime US3054014A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DEP23114A DE1088155B (de) 1959-07-08 1959-07-08 Elektrode fuer elektrische Hochdruckentladungslampen

Publications (1)

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US3054014A true US3054014A (en) 1962-09-11

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US39408A Expired - Lifetime US3054014A (en) 1959-07-08 1960-06-28 Electrode for high-pressure electric discharge lamps

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US (1) US3054014A (zh)
DE (1) DE1088155B (zh)
FR (1) FR1262280A (zh)
GB (1) GB962651A (zh)
NL (2) NL253509A (zh)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4117367A (en) * 1974-05-13 1978-09-26 U.S. Philips Corporation High-pressure discharge lamp
FR2490005A1 (fr) * 1980-09-05 1982-03-12 Philips Nv Lampe a decharge dans la vapeur de sodium a haute pression
US4628225A (en) * 1982-11-02 1986-12-09 W. C. Heraeus Gmbh Electrode for laser stimulation lamps
US4906895A (en) * 1987-07-14 1990-03-06 Patent Treuhand Gesellschaft Fur Elektrische Gluhlampen M.B.H. High-pressure discharge lamp with stabilized arc
US5629585A (en) * 1994-09-21 1997-05-13 Patent-Treuhand-Gesellschaft F. Elektrische Gluehlampen Mbh High-pressure discharge lamp, particularly low-rated power discharge lamp, with enhanced quality of light output
WO2008074361A1 (de) * 2006-12-18 2008-06-26 Osram Gesellschaft mit beschränkter Haftung Elektrode für eine entladungslampe
JP2012109180A (ja) * 2010-11-19 2012-06-07 Yumex Inc ショートアーク放電灯用電極及びその製造方法
CN107785230A (zh) * 2017-11-02 2018-03-09 常州玉宇电光器件有限公司 高触发性阴极及其制作工艺

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3328623A (en) * 1964-03-02 1967-06-27 Sylvania Electric Prod Surge arrestor having electrodes containing a low resistivity metal
US3789255A (en) * 1972-01-12 1974-01-29 Westinghouse Electric Corp Non-sag incandescent tungsten filament for an incandescent lamp
DE102004043247B4 (de) * 2004-09-07 2010-04-15 Osram Gesellschaft mit beschränkter Haftung Elektrode für Hochdruckentladungslampen sowie Hochdruckentladungslampe mit derartigen Elektroden
JP5024466B1 (ja) * 2011-03-10 2012-09-12 ウシオ電機株式会社 ショートアーク型放電ランプ

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1082933A (en) * 1912-06-19 1913-12-30 Gen Electric Tungsten and method of making the same for use as filaments of incandescent electric lamps and for other purposes.
US1461118A (en) * 1917-12-19 1923-07-10 Westinghouse Lamp Co Filament
US1569095A (en) * 1926-01-12 laise
US1723862A (en) * 1920-05-07 1929-08-06 Gen Electric Process for the manufacture of drawn tungsten wires
GB573141A (en) * 1940-11-12 1945-11-08 Siemens Electric Lamps & Suppl Improvements relating to electric discharge lamps
US2716713A (en) * 1950-03-22 1955-08-30 Gen Electric Cold electrode pulse lamp structure

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB569651A (en) * 1939-01-27 1945-06-04 Siemens Electric Lamps & Suppl Improvements in or relating to electric discharge lamps

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1569095A (en) * 1926-01-12 laise
US1082933A (en) * 1912-06-19 1913-12-30 Gen Electric Tungsten and method of making the same for use as filaments of incandescent electric lamps and for other purposes.
US1461118A (en) * 1917-12-19 1923-07-10 Westinghouse Lamp Co Filament
US1723862A (en) * 1920-05-07 1929-08-06 Gen Electric Process for the manufacture of drawn tungsten wires
GB573141A (en) * 1940-11-12 1945-11-08 Siemens Electric Lamps & Suppl Improvements relating to electric discharge lamps
US2716713A (en) * 1950-03-22 1955-08-30 Gen Electric Cold electrode pulse lamp structure

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4117367A (en) * 1974-05-13 1978-09-26 U.S. Philips Corporation High-pressure discharge lamp
FR2490005A1 (fr) * 1980-09-05 1982-03-12 Philips Nv Lampe a decharge dans la vapeur de sodium a haute pression
US4628225A (en) * 1982-11-02 1986-12-09 W. C. Heraeus Gmbh Electrode for laser stimulation lamps
US4906895A (en) * 1987-07-14 1990-03-06 Patent Treuhand Gesellschaft Fur Elektrische Gluhlampen M.B.H. High-pressure discharge lamp with stabilized arc
US5629585A (en) * 1994-09-21 1997-05-13 Patent-Treuhand-Gesellschaft F. Elektrische Gluehlampen Mbh High-pressure discharge lamp, particularly low-rated power discharge lamp, with enhanced quality of light output
EP0703600A3 (de) * 1994-09-21 1998-05-06 Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH Hochdruckentladungslampe
WO2008074361A1 (de) * 2006-12-18 2008-06-26 Osram Gesellschaft mit beschränkter Haftung Elektrode für eine entladungslampe
US20100039035A1 (en) * 2006-12-18 2010-02-18 Adam Kotowicz Electrode for a Discharge Lamp
CN101536141B (zh) * 2006-12-18 2011-07-27 奥斯兰姆有限公司 用于放电灯的电极
US8138662B2 (en) 2006-12-18 2012-03-20 Osram Ag Electrode for a discharge lamp
JP2012109180A (ja) * 2010-11-19 2012-06-07 Yumex Inc ショートアーク放電灯用電極及びその製造方法
CN107785230A (zh) * 2017-11-02 2018-03-09 常州玉宇电光器件有限公司 高触发性阴极及其制作工艺
CN107785230B (zh) * 2017-11-02 2024-06-04 常州玉宇电光器件有限公司 高触发性阴极及其制作工艺

Also Published As

Publication number Publication date
FR1262280A (fr) 1961-05-26
NL253509A (zh)
NL109963C (zh)
DE1088155B (de) 1960-09-01
GB962651A (en) 1964-07-01

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