EP0299230B1 - Kathode für eine Hochdruckentladungslampe - Google Patents

Kathode für eine Hochdruckentladungslampe Download PDF

Info

Publication number
EP0299230B1
EP0299230B1 EP88109786A EP88109786A EP0299230B1 EP 0299230 B1 EP0299230 B1 EP 0299230B1 EP 88109786 A EP88109786 A EP 88109786A EP 88109786 A EP88109786 A EP 88109786A EP 0299230 B1 EP0299230 B1 EP 0299230B1
Authority
EP
European Patent Office
Prior art keywords
cathode
tip
cone
carbide layer
carbide
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
EP88109786A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0299230A1 (de
Inventor
Wolfgang Dr. Pabst
Manfred Dr. Rehmet
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
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
Application filed by Patent Treuhand Gesellschaft fuer Elektrische Gluehlampen mbH filed Critical Patent Treuhand Gesellschaft fuer Elektrische Gluehlampen mbH
Publication of EP0299230A1 publication Critical patent/EP0299230A1/de
Application granted granted Critical
Publication of EP0299230B1 publication Critical patent/EP0299230B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • 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

  • the invention relates to a cathode for a high-pressure discharge lamp according to the preamble of claim 1.
  • an electrode for high-pressure discharge lamps with gas or steam filling is known, which is made of a thorium dioxide-containing tungsten rod. Since these lamps are preferably used in devices with an optical beam path, the problems of arc disturbance and intensity fluctuation, associated with the premature destruction of the tip of the electrode serving as the cathode, occur more frequently than electrodes for electron tube construction. In recent years, increased demands have been placed on such lamps in this regard. Among other things this is due to the development of new areas of application.
  • the invention has for its object to reduce the intensity fluctuations of the arc, to contain the uneven arc and to prevent premature destruction of the cathode tip.
  • a region at the tip of the cathode can be particularly advantageously completely free of carbide.
  • Such cathodes are used in short-arc lamps (high-pressure xenon lamps and high-pressure mercury lamps), which may have temperatures in the area of the cathode tip which exceed the melting temperature of tungsten carbide (2710 ° C.). If tungsten carbide were present in this area, this would lead to a partial melting of the tip. The result would be a difficult post-diffusion of thorium and an increase in the work function, combined with an increase in the uneven arch.
  • GB-PS 929 668 and DE-OS 32 05 746 are generally concerned with electrodes for electron tube construction.
  • These electrodes consist of a high-melting material, usually tungsten, which is doped with an electron-emitting material, usually Th0 2 .
  • the proportion of Th0 2 can vary within wide limits (0.1-5% by weight) depending on the application.
  • elemental emitter material is formed due to the high temperature, which migrates to the surface preferably by diffusion along the grain boundaries. This process is crucial for the quality of the electrode and can be influenced by various measures.
  • the grain structure can also be changed by further doping (e.g. potassium, aluminum) so that the grain boundary diffusion is further facilitated.
  • further doping e.g. potassium, aluminum
  • FIG. 1 schematically shows a xenon short arc lamp 1 operated with direct current and having a low wattage (e.g. 150 W), which e.g. is used as a projection light source and in spectrophotometers and color reproduction devices.
  • the elliptical discharge vessel 2 made of quartz glass is filled with xenon (operating pressure approx. 50 bar).
  • the anode 3 and the cathode 4 are arranged axially in the discharge vessel at a distance of approximately 2 mm from one another.
  • Each electrode has a shaft 5.
  • the electrical supply takes place in a known manner via molybdenum foils 6, which are connected to the metal sleeve bases 7 via pins.
  • the molybdenum foils 6 are sealed in a vacuum-tight manner in the two ends of the discharge vessel 2.
  • another technique e.g. Rod melting or cup melting can be used.
  • the anode 3 is made as a solid cylinder block from hammered tungsten and has a wide, slightly bevelled end face.
  • the comparatively small cathode 4 is made of tungsten which is doped with 0.4% by weight Th0 2 . It is shown enlarged in FIG. 2 (but not to scale).
  • the cylindrical base body 8 of the cathode 4 tapers in the manner of a cone 9, the tip 10 of which is truncated.
  • the cone forms an opening angle a of 25 ° and has an overall length of approximately 4 mm.
  • the cone 9 is surrounded by a layer 11 of tungsten carbide over two thirds of its length. The layer thickness is approximately 10 ⁇ m.
  • the remaining third of the cone length is kept free of carbide.
  • the minimum width of the free zone at the cathode tip is 0.7 mm. This minimum width is essentially determined by the temperature distribution at the cathode tip. This free zone ensures that the tip cannot melt due to the lower melting temperature of the tungsten carbide layer compared to tungsten.
  • the carbide layer is produced by separating carbon from a carbon-containing gas, for example CH 4 (CVD process). To achieve a layer thickness of 10 ⁇ m, egg Maintain a gas flow of approx. 1 l / min over 10 minutes at 2100 ° C. The zone to be kept clear at the top of the cone is covered by depressions in the batch carrier. In this process, the cylindrical body is also partially covered with a carbide layer. However, this is meaningless for the essence of the invention.
  • a carbon-containing gas for example CH 4 (CVD process
  • lamps which were equipped with these cathodes were able to keep the luminance fluctuation caused by the uneven arc below 4% and the intensity drift occurring in continuous operation below 1% per hour. Premature failures due to melting of the tip were not observed.
  • the entire cone is covered by a carbide layer, the thickness of the layer continuously decreasing from the base to the tip of the cone. This can be done by dipping, brushing, spraying or the like. achieve, with adequate measures (drainage, etching) ensuring sufficient thinning towards the tip.
  • the shape of the cathode can be designed differently; e.g. can instead of a cone a hemisphere or similar be used.

Landscapes

  • Discharge Lamp (AREA)
EP88109786A 1987-07-14 1988-06-20 Kathode für eine Hochdruckentladungslampe Expired - Lifetime EP0299230B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3723271 1987-07-14
DE19873723271 DE3723271A1 (de) 1987-07-14 1987-07-14 Kathode fuer eine hochdruckentladungslampe

Publications (2)

Publication Number Publication Date
EP0299230A1 EP0299230A1 (de) 1989-01-18
EP0299230B1 true EP0299230B1 (de) 1990-09-12

Family

ID=6331556

Family Applications (1)

Application Number Title Priority Date Filing Date
EP88109786A Expired - Lifetime EP0299230B1 (de) 1987-07-14 1988-06-20 Kathode für eine Hochdruckentladungslampe

Country Status (4)

Country Link
US (1) US4906895A (enrdf_load_stackoverflow)
EP (1) EP0299230B1 (enrdf_load_stackoverflow)
JP (1) JPS6424355A (enrdf_load_stackoverflow)
DE (2) DE3723271A1 (enrdf_load_stackoverflow)

Families Citing this family (25)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3904552A1 (de) * 1989-02-15 1990-08-16 Patent Treuhand Ges Fuer Elektrische Gluehlampen Mbh Hochdruckentladungslampe fuer den betrieb mit wechselstrom
US5107165A (en) * 1990-11-01 1992-04-21 General Electric Company Initial light output for metal halide lamp
US6243057B1 (en) 1990-11-16 2001-06-05 Digital Projection Limited Deformable mirror device driving circuit and method
US6561675B1 (en) 1995-01-27 2003-05-13 Digital Projection Limited Rectangular beam generating light source
US5420477A (en) * 1993-01-15 1995-05-30 Welch Allyn, Inc. Electrode for metal halide discharge lamp
DE9415217U1 (de) * 1994-09-21 1996-01-25 Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH, 81543 München Hochdruckentladungslampe
EP0714118B1 (en) * 1994-11-25 2002-07-24 Ushiodenki Kabushiki Kaisha Metal halide lamp of the short arc type
DE19738574A1 (de) * 1997-09-04 1999-03-11 Patent Treuhand Ges Fuer Elektrische Gluehlampen Mbh Elektrode und Verfahren sowie Vorrichtung zur Herstellung derselben
US6215247B1 (en) * 1997-10-03 2001-04-10 Orc Manufacturing Co., Ltd. Construction of electrode for high pressure discharge lamp and process for producing the same
AU2956899A (en) 1998-03-20 1999-10-18 Hamamatsu Photonics K.K. Discharge tube for light source
DE19835476A1 (de) * 1998-08-06 2000-02-10 Patent Treuhand Ges Fuer Elektrische Gluehlampen Mbh Elektrode für eine Hochdruckentladungslampe mit langer Lebensdauer
NL1010374C2 (nl) * 1998-10-22 2000-04-26 Orc Manufacturing Co Constructie van elektrode voor hogedruk ontladingslamp en werkwijze voor de vervaardiging daarvan.
JP2000306546A (ja) 1999-04-21 2000-11-02 Ushio Inc ショートアーク放電ランプ
JP2000323091A (ja) 1999-05-12 2000-11-24 Hamamatsu Photonics Kk 光源用放電管
JP2005108435A (ja) * 1999-06-30 2005-04-21 Hamamatsu Photonics Kk フラッシュランプ
JP2001319617A (ja) * 2000-05-08 2001-11-16 Ushio Inc 超高圧水銀ランプ
JP3596453B2 (ja) * 2000-09-28 2004-12-02 ウシオ電機株式会社 ショートアーク放電ランプ
JP3926211B2 (ja) * 2002-05-29 2007-06-06 日本碍子株式会社 高圧水銀灯および高圧水銀灯用封止材
JP4295527B2 (ja) * 2003-02-27 2009-07-15 株式会社アライドマテリアル 放電ランプ及びその電極構造
DE102006023970A1 (de) * 2006-05-22 2007-11-29 Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH Elektrode für eine Entladungslampe sowie ein Verfahren zum Herstellen einer derartigen Elektrode
DE102008014096A1 (de) 2008-03-05 2009-09-10 Osram Gesellschaft mit beschränkter Haftung Wolframelektrode für Hochdruckentladungslampen und Hochdruckentladungslampe mit einer Wolframelektrode
JP5293172B2 (ja) * 2008-12-26 2013-09-18 ウシオ電機株式会社 放電ランプ
JP5299132B2 (ja) * 2009-07-07 2013-09-25 ウシオ電機株式会社 デジタルプロジェクター用キセノンショートアークランプ
CN102366837A (zh) * 2011-08-10 2012-03-07 厦门虹鹭钨钼工业有限公司 一种高压气体放电灯用钍钨-钨复合电极的制作方法
JP6493796B2 (ja) * 2015-04-06 2019-04-03 ウシオ電機株式会社 ショートアーク型放電ランプ

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL253509A (enrdf_load_stackoverflow) * 1959-07-08
GB929668A (en) * 1960-09-28 1963-06-26 Gen Electric Co Ltd Improvements in or relating to electrodes for electric discharge apparatus
JPS5572352A (en) * 1978-11-28 1980-05-31 Ushio Inc Anode for electric discharge lamp and its production method
JPS579044A (en) * 1980-06-19 1982-01-18 Mitsubishi Electric Corp Electrode for discharge lamp
DE3205746A1 (de) * 1982-02-18 1983-08-25 Philips Patentverwaltung Gmbh, 2000 Hamburg Thermionische kathode und verfahren zu ihrer herstellung
JPS60131751A (ja) * 1983-12-20 1985-07-13 Hamamatsu Photonics Kk 光源用放電管

Also Published As

Publication number Publication date
DE3723271A1 (de) 1989-01-26
JPH0586026B2 (enrdf_load_stackoverflow) 1993-12-09
US4906895A (en) 1990-03-06
JPS6424355A (en) 1989-01-26
DE3860599D1 (de) 1990-10-18
EP0299230A1 (de) 1989-01-18

Similar Documents

Publication Publication Date Title
EP0299230B1 (de) Kathode für eine Hochdruckentladungslampe
DE3716485C1 (de) Xenon-Kurzbogen-Entladungslampe
EP0703600B1 (de) Hochdruckentladungslampe
EP1481418B1 (de) Kurzbogen-hochdruckentladungslampe
EP0536609A1 (de) Hochdruckentladungslampe
DE10291427B4 (de) Halogen-Metalldampflampe für einen Kraftfahrzeugscheinwerfer
DE2641880C2 (enrdf_load_stackoverflow)
DE102010011980A1 (de) Entladungslampe vom Kurzbogentyp
DE69125272T2 (de) Verbesserte elektrode für metallhalogenidentladungslampe
DE69731374T2 (de) Niederdruckentladunglampe
DE69502581T2 (de) Entladungslampe
DE102006024238A1 (de) Hochdruckentladungslampe
DE2920042A1 (de) Kurzbogenentladungslampe
DE3429105A1 (de) Metalldampfentladungslampe
EP1481417A1 (de) Quecksilber-kurzbogenlampe mit lanthanoxid-haltiger kathode
DE102006052715B4 (de) Verfahren zur Herstellung einer quecksilberfreien Bogenentladungsröhre mit jeweils einem Einkristall an den Elektrodenspitzen
EP0472100A2 (de) Hochdruckentladungslampe
DE69032825T2 (de) Niederdruckedelgasentladungslampe
EP0825636A2 (de) Hochdruckentladungslampe
DE3240359C2 (enrdf_load_stackoverflow)
DE2656264C3 (de) Leitungseinführung für eine Hochdruck-Dampfentladungslampe
DE60022428T2 (de) Elektrode für eine Metall-Halogenlampe
DE880360C (de) Elektrische kugelfoermige Hochdruckentladungslampe
DE748762C (de) Elektrische Hochdruckentladungslampe mit flachem Entladungsrohr
DE3037223A1 (de) Entladungslampe

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): DE FR GB IT

17P Request for examination filed

Effective date: 19890208

RAP3 Party data changed (applicant data changed or rights of an application transferred)

Owner name: PATENT-TREUHAND-GESELLSCHAFT FUER ELEKTRISCHE GLUE

17Q First examination report despatched

Effective date: 19900103

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): DE FR GB IT

REF Corresponds to:

Ref document number: 3860599

Country of ref document: DE

Date of ref document: 19901018

ET Fr: translation filed
ITF It: translation for a ep patent filed
GBT Gb: translation of ep patent filed (gb section 77(6)(a)/1977)
PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed
ITTA It: last paid annual fee
REG Reference to a national code

Ref country code: GB

Ref legal event code: IF02

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: GB

Payment date: 20050607

Year of fee payment: 18

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: FR

Payment date: 20050617

Year of fee payment: 18

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20060620

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: IT

Payment date: 20060630

Year of fee payment: 19

GBPC Gb: european patent ceased through non-payment of renewal fee

Effective date: 20060620

REG Reference to a national code

Ref country code: FR

Ref legal event code: ST

Effective date: 20070228

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DE

Payment date: 20070822

Year of fee payment: 20

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: FR

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20060630

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: IT

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20070620