EP0549056B1 - Electric discharge lamp - Google Patents

Electric discharge lamp Download PDF

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Publication number
EP0549056B1
EP0549056B1 EP19920203956 EP92203956A EP0549056B1 EP 0549056 B1 EP0549056 B1 EP 0549056B1 EP 19920203956 EP19920203956 EP 19920203956 EP 92203956 A EP92203956 A EP 92203956A EP 0549056 B1 EP0549056 B1 EP 0549056B1
Authority
EP
European Patent Office
Prior art keywords
tube
discharge vessel
lamp
wire
outer bulb
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
EP19920203956
Other languages
German (de)
French (fr)
Other versions
EP0549056A1 (en
Inventor
Henrikus Johannes Hubertus Pragt
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.)
Koninklijke Philips NV
Original Assignee
Koninklijke Philips Electronics NV
Philips Electronics NV
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 Koninklijke Philips Electronics NV, Philips Electronics NV filed Critical Koninklijke Philips Electronics NV
Publication of EP0549056A1 publication Critical patent/EP0549056A1/en
Application granted granted Critical
Publication of EP0549056B1 publication Critical patent/EP0549056B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00—Gas-discharge or vapour-discharge lamps
    • H01J61/02—Details
    • H01J61/50—Auxiliary parts or solid material within the envelope for reducing risk of explosion upon breakage of the envelope, e.g. for use in mines

Definitions

  • the invention relates to an electric discharge lamp comprising:
  • the glass tube is surrounded by a meshwork of metal wire which is fixed around the tube with metal clamping strips.
  • the clamping strips are electrically conducting and connected to a live mount which supports the discharge vessel and the tube.
  • the meshwork as a result is under electrical tension, which can lead to the disappearance of sodium from the discharge vessel if the latter contains sodium. Changes in lamp characteristics are the result of this.
  • EP-A-0 186 899 discloses an electric discharge lamp in which a rigid current conductor to an electrode has a coiled portion which encloses and supports a glass tube surrounding the discharge vessel. Thereby, said portion is current conducting, entailing the risk of causing sodium loss from the discharge vessel.
  • US-A-4 950 938 discloses an electric discharge lamp in which the discharge vessel is enveloped by a shield of metal gauze.
  • the metal gauze is mounted in an electrically floating manner in that it is secured to the current conductors by means of electrically insulating bridges.
  • the light transmitting metal part is a helically coiled metal wire which surrounds the glass tube and is supported by this tube so as to be electrically floating.
  • the wire may be fastened to the tube, for example, in that ends of the wire are fastened to the tube with cement or are fused into the tube.
  • a very attractive, convenient and reliable fastening is one in which the wire is fixed around the tube by its own clamping force.
  • the wire has in that case been coiled on a mandrel with a smaller diameter than the tube, and has been twisted, for example against its coiling direction, during assembly so as to give its turns a larger diameter. After the wire has been applied around the tube, the twisting force is released and the wire will surround the tube with clamping fit.
  • the wire provides a good electrical screening of the current conductor which runs alongside the discharge vessel and also on that account counteracts the disappearance of sodium, if this should be present in the discharge vessel.
  • the construction provides a reliable protection against damage to the outer bulb in the case of an exploding discharge vessel. The influence on the luminous flux of the lamp is very slight.
  • the electric discharge lamp has an outer bulb 1 which is closed in a gastight manner and which accommodates a discharge vessel 2 which is closed in a gastight manner and which has an axis 3 and seals 4 on its axis.
  • a glass tube 10 for example, made of quartz glass or of hardglass, axially surrounds the discharge vessel.
  • the tube has a surrounding part 11.
  • a pair of electrodes 6 is present in the discharge vessel in an ionizable medium.
  • Current conductors 7 extend from outside the outer bulb to the pair of electrodes and are connected thereto.
  • the glass tube 10 is fastened to a current conductor 7 by means of clamping strips 5.
  • the tube may have a wall thickness of, for example, 1 mm or less.
  • a helically coiled metal wire 11 surrounds the glass tube 10 and is fixed around said tube so as to be electrically floating.
  • resistance wire may be used, for example, kanthal wire or tantalum wire.
  • wire of 0.25 mm diameter is used, coiled with a pitch of 5 mm.
  • a thinner wire for example of 0.2 mm, or a greater pitch may be used, for example 7 mm.
  • the coiled wire is thin and has an open structure. Influence on the luminous flux of the lamp, therefore, is scarcely perceivable.
  • the wire 11 is fixed around the tube 10 by its own clamping force.
  • the lamp shown in a high-pressure metal halide discharge lamp which contains metal halides, mercury, and rare gas.
  • the lamp consumes a power of 70 W during operation.
  • the wire surrounding the tube is electrically floating. Disappearance of sodium, if present, from the discharge vessel is effectively counteracted by this. If an electron should be detached from the wire by UV radiation, the wire is given a positive potential which slows down further electron losses. Moreover, the wire effectively screens the current conductor extending alongside the discharge vessel from the discharge.

Description

  • The invention relates to an electric discharge lamp comprising:
    • an outer bulb closed in a gastight manner;
    • a discharge vessel closed in a gastight manner and having an axis and seals on its axis, a pair of electrodes being arranged in said discharge vessel;
    • a glass tube axially surrounding the discharge vessel;
    • a light-transmitting metal part surrounding the tube; and
    • current conductors which extend from outside the outer bulb to the pair of electrodes and are connected thereto.
  • Such an electric lamp is known from US 4 721 876.
  • In the known lamp, the glass tube is surrounded by a meshwork of metal wire which is fixed around the tube with metal clamping strips. The clamping strips are electrically conducting and connected to a live mount which supports the discharge vessel and the tube. The meshwork as a result is under electrical tension, which can lead to the disappearance of sodium from the discharge vessel if the latter contains sodium. Changes in lamp characteristics are the result of this.
  • It is an object of the construction of the known lamp to keep the outer bulb intact if the discharge vessel should explode. Explosion may occur when the lamp reaches the end of its life.
  • The construction of the known lamp is complicated. The manufacture of the meshwork, or of a braided assembly, and its manipulation are difficult. Another disadvantage is the risk of sodium disappearance.
  • EP-A-0 186 899 discloses an electric discharge lamp in which a rigid current conductor to an electrode has a coiled portion which encloses and supports a glass tube surrounding the discharge vessel. Thereby, said portion is current conducting, entailing the risk of causing sodium loss from the discharge vessel.
  • US-A-4 950 938 discloses an electric discharge lamp in which the discharge vessel is enveloped by a shield of metal gauze. The metal gauze is mounted in an electrically floating manner in that it is secured to the current conductors by means of electrically insulating bridges.
  • It is an object of the invention to provide an electric lamp of the kind mentioned in the opening paragraph which is of a simple and reliable construction.
  • According to the invention, this object is achieved in that the light transmitting metal part is a helically coiled metal wire which surrounds the glass tube and is supported by this tube so as to be electrically floating.
  • The wire may be fastened to the tube, for example, in that ends of the wire are fastened to the tube with cement or are fused into the tube.
  • A very attractive, convenient and reliable fastening is one in which the wire is fixed around the tube by its own clamping force. The wire has in that case been coiled on a mandrel with a smaller diameter than the tube, and has been twisted, for example against its coiling direction, during assembly so as to give its turns a larger diameter. After the wire has been applied around the tube, the twisting force is released and the wire will surround the tube with clamping fit.
  • In spite of the comparatively great pitch which the wire may have, for example several mm, for example 4 or 9 mm, the wire provides a good electrical screening of the current conductor which runs alongside the discharge vessel and also on that account counteracts the disappearance of sodium, if this should be present in the discharge vessel. The construction provides a reliable protection against damage to the outer bulb in the case of an exploding discharge vessel. The influence on the luminous flux of the lamp is very slight.
  • An embodiment of the electric lamp according to the invention is shown in side elevation in the drawing.
  • In the Figure, the electric discharge lamp has an outer bulb 1 which is closed in a gastight manner and which accommodates a discharge vessel 2 which is closed in a gastight manner and which has an axis 3 and seals 4 on its axis. A glass tube 10, for example, made of quartz glass or of hardglass, axially surrounds the discharge vessel. The tube has a surrounding part 11. A pair of electrodes 6 is present in the discharge vessel in an ionizable medium. Current conductors 7 extend from outside the outer bulb to the pair of electrodes and are connected thereto. The glass tube 10 is fastened to a current conductor 7 by means of clamping strips 5. The tube may have a wall thickness of, for example, 1 mm or less.
  • A helically coiled metal wire 11 surrounds the glass tube 10 and is fixed around said tube so as to be electrically floating.
  • To achieve this, for example, resistance wire may be used, for example, kanthal wire or tantalum wire. In the lamp shown, wire of 0.25 mm diameter is used, coiled with a pitch of 5 mm. Alternatively, however, a thinner wire, for example of 0.2 mm, or a greater pitch may be used, for example 7 mm. The coiled wire is thin and has an open structure. Influence on the luminous flux of the lamp, therefore, is scarcely perceivable.
  • The wire 11 is fixed around the tube 10 by its own clamping force.
  • The lamp shown in a high-pressure metal halide discharge lamp which contains metal halides, mercury, and rare gas. The lamp consumes a power of 70 W during operation.
  • During stable lamp operation, the discharge vessel was made to explode by means of a current surge. The outer bulb remained entirely undamaged during this, which proves that the construction of the lamp effectively protects the surroundings against the consequences of an explosion of the discharge vessel.
  • The wire surrounding the tube is electrically floating. Disappearance of sodium, if present, from the discharge vessel is effectively counteracted by this. If an electron should be detached from the wire by UV radiation, the wire is given a positive potential which slows down further electron losses. Moreover, the wire effectively screens the current conductor extending alongside the discharge vessel from the discharge.
  • It was found that the construction is sufficiently effective and reliable when the wire surrounds the pair of electrodes, i.e. the cavity of the discharge vessel, laterally.

Claims (3)

  1. An electric discharge lamp comprising:
    an outer bulb (1) closed in a gastight manner;
    a discharge vessel (2) closed in a gastight manner and having an axis (3) and seals (4) on its axis, a pair of electrodes being arranged in said discharge vessel;
    a glass tube (10) axially surrounding the discharge vessel;
    a light-transmitting metal part (11) surrounding the tube; and
    current conductors (7) which extend from outside the outer bulb to the pair of electrodes and are connected thereto,
    characterized in that the light transmitting metal part is a helically coiled metal wire (11) which surrounds the glass tube (10) and is supported by this tube so as to be electrically floating.
  2. An electric lamp as claimed in Claim 1, characterized in that the metal wire (11) is fastened to the tube (10).
  3. An electric lamp as claimed in Claim 1, characterized in that the metal wire (11) is fixed around the tube (10) by its own clamping force.
EP19920203956 1991-12-23 1992-12-16 Electric discharge lamp Expired - Lifetime EP0549056B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP91203379 1991-12-23
EP91203379 1991-12-23

Publications (2)

Publication Number Publication Date
EP0549056A1 EP0549056A1 (en) 1993-06-30
EP0549056B1 true EP0549056B1 (en) 1996-05-22

Family

ID=8208095

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19920203956 Expired - Lifetime EP0549056B1 (en) 1991-12-23 1992-12-16 Electric discharge lamp

Country Status (3)

Country Link
EP (1) EP0549056B1 (en)
JP (1) JPH05314952A (en)
DE (1) DE69210973T2 (en)

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5402033A (en) * 1991-12-23 1995-03-28 Philips Electronics North America Corporation High pressure discharge lamp having clamped-on containment sleeve
US5532543A (en) * 1991-12-23 1996-07-02 Philips Electronics North America Corporation High density discharge lamp with pinched-on containment shield
US6153968A (en) * 1998-10-02 2000-11-28 Philips Electronics North America Corp. Metal halide lamp with stem mounted support frame for arc tube shield
US6833677B2 (en) 2001-05-08 2004-12-21 Koninklijke Philips Electronics N.V. 150W-1000W mastercolor ceramic metal halide lamp series with color temperature about 4000K, for high pressure sodium or quartz metal halide retrofit applications
US6995513B2 (en) 2001-05-08 2006-02-07 Koninklijke Philips Electronics N.V. Coil antenna/protection for ceramic metal halide lamps
JP2006228584A (en) * 2005-02-18 2006-08-31 Iwasaki Electric Co Ltd High pressure discharge lamp
WO2007122522A2 (en) * 2006-04-21 2007-11-01 Koninklijke Philips Electronics, N.V. Discharge lamp with protective shroud
JP2008027745A (en) * 2006-07-21 2008-02-07 Osram Melco Toshiba Lighting Kk Metal halide lamp, and lighting apparatus

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA1239970A (en) * 1984-12-28 1988-08-02 Francis R. Koza Metal halide lamp with arc tube shield support
US4942330A (en) * 1988-09-30 1990-07-17 Gte Products Corporation Lamp assembly utilizing shield and ceramic fiber mesh for containment
US4950938A (en) * 1988-11-16 1990-08-21 North American Philips Corp. Discharge lamp with discharge vessel rupture shield

Also Published As

Publication number Publication date
DE69210973T2 (en) 1996-11-28
DE69210973D1 (en) 1996-06-27
JPH05314952A (en) 1993-11-26
EP0549056A1 (en) 1993-06-30

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