EP0011993A1 - Elektrische Entladungslampen - Google Patents

Elektrische Entladungslampen Download PDF

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Publication number
EP0011993A1
EP0011993A1 EP79302675A EP79302675A EP0011993A1 EP 0011993 A1 EP0011993 A1 EP 0011993A1 EP 79302675 A EP79302675 A EP 79302675A EP 79302675 A EP79302675 A EP 79302675A EP 0011993 A1 EP0011993 A1 EP 0011993A1
Authority
EP
European Patent Office
Prior art keywords
tube
lamp according
intermediate portion
lamp
closures
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.)
Withdrawn
Application number
EP79302675A
Other languages
English (en)
French (fr)
Inventor
Kenneth Edward Thorn Lighting Limited Brown
Alan George Thorn Lighting Limited Chalmers
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.)
Thorn EMI Ltd
Original Assignee
Thorn EMI PLC
Thorn EMI Ltd
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 Thorn EMI PLC, Thorn EMI Ltd filed Critical Thorn EMI PLC
Publication of EP0011993A1 publication Critical patent/EP0011993A1/de
Withdrawn legal-status Critical Current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
    • H01J61/30—Vessels; Containers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00—Gas-discharge or vapour-discharge lamps
    • H01J61/02—Details
    • H01J61/36—Seals between parts of vessels; Seals for leading-in conductors; Leading-in conductors
    • H01J61/361—Seals between parts of vessel

Definitions

  • This invention relates to electric discharge lamps and more especially to the provision of improved ceramic arc tubes for high pressure, metal halide lamps.
  • Discharge lamps operating at relatively low power but with high efficacy for example low power, high pressure metal halide lamps, have of necessity a high power loading (watts per unit arc length) and a high power density (watts per unit arc tube volume).
  • the arc tube walls consequently attain a high operating temperature and silica is not a satisfactory material for the tube if the lamp is to have a long life.
  • Ceramic materials, for example alumina can withstand a high temperature, are chemically less reactive than silica, can easily be made in small sizes and are therefore suitable for use in this type of lamp.
  • the equilibrium temperature of any part of the arc tube is determined by the balance between the inflow and outflow of heat, and in regions remote from the discharge (for example, in the vicinity of the seals, where the cool spot is usually situated) heat losses are due mainly to radiation, and increase with increasing temperature, surface area and emittance of the material employed.
  • heat losses are due mainly to radiation, and increase with increasing temperature, surface area and emittance of the material employed.
  • the large area of the pinch seals which have high emittance, limits the cool spot temperatures that can be attained.
  • cermet materials which may be used to seal the tube also exhibit high emittance, and notably a higher emittance than that of the ceramic materials themselves.
  • a further problem in ceramic lamps of small dimensions is that of making the final seal without loss of volatile fill substances. Sealing involves heating parts of the arc lamp to a high temperature, perhaps even above 1600 C, with the dose only about a centimetre away. We have found upon investigation that in the early stages of the sealing process the transfer of heat to the doses of volatile substances is mainly due to direct radiation from the heat region.
  • the present invention is concerned with the design of ceramic arc tubes in which heat losses from the tube ends are reduced and cool spot temperature increased.
  • the invention is also concerned to provide arc tubes of ceramic material in which final sealing can be accomplished without loss of volatile substances, by reducing the transfer of heat to the substances from the heated region of the seal.
  • an arc tube for a high pressure, metal halide, electric discharge lamp comprising a tube of light- transmitting ceramic having end portions which are of smaller cross-sectional area than an intermediate portion and are adapted to be sealed to end closures of compatible. cermet-of corresponding diameter.
  • the intermediate portion of the tube is substantiall cylindrical, and the end portions are substantially cylindrical and of smaller diameter, and are connected with the intermediate portion by respective integral shoulder portions.
  • the electrodes should be carried on conductive supports of such lengths that the electrodes are disposed in the vicinity of the shoulder portions of the lamp.
  • the intermediate portion has a maximum diameter in the central region of the tube and tapers inwardly in both directions respective orifices of reduced diameter at the tube ends, to which the cermet closures are sealed.
  • This tapering form of lamp'tube maintains a more nearly isothermal temperature distribution along its length.
  • the intermediate portion is substantially cylindrical, and the end portions are of integral shouldered form, terminating in respective orifices of reduced diameter to which the cermet closures are sealed.
  • the electrodes should be carried on short supports so that they are located within the shouldered end regions of the tube.
  • This form of tube requires suitably shaped end plugs of cermet material, for example as described in our German Specification OS 26 55 726, which are preferably sealed with the application of pressure in the axial direction.
  • the principles of this invention are applicable to any ceramic material suitable for the fabrication of arc lamp envelopes and to any cermet material suitable for use in end closures for such tubes.
  • suitable ceramic materials include translucent polycrystalline and single crystal alumina ceramics, such as those available under the Trade Mark "STELLOX”.
  • the arc tubes may be made in several ways.
  • the ceramic powder can be moulded and compacted to the desired shape, using a 'lost wax' process, prior to sintering.
  • a 'green-state' or partly sintered tube can be machined to shape.
  • Yet another, and simpler, method is to assemble apertured plugs at the end of a length of tube in the green state, giving a structure which will be integrated by sintering and may subsequently be trimmed.
  • Useful cermet materials which may be conductive or may include integral conductive and insulating regions, may be made by compacting and sintering granules of refractory oxide, such as alumina, which have been coated with a metal such as tungsten, molybdenum or tantalum, e.g. by rolling in the metal powder.
  • refractory oxide such as alumina
  • metal such as tungsten, molybdenum or tantalum
  • the materials of the former application are ceramic materials composed of a refractory oxide, such as alumina, with minor amounts of other oxides.
  • the materials of the latter application are halide resistant glasses based on rare earth oxides, such as lanthanum oxide, with minor amounts of boric oxide and other oxides. These materials may conveniently be preformed into elements of appropriate shape.
  • an arc tube 10 for a low power, high efficacy, metal halide discharge lamp comprises a substantially cylindrical main portion 11, which may, for example, be up to 2 cm in length. Respective cylindrical end portions 12 are connected with the main portion 11 by integral shoulders 13:
  • the arc tube is preferably composed of translucent alumina ceramic such as the 'STELLOX' material referred to above.
  • the tube may be fabricated by machining to shape a 'green' or partly sintered tube, or by a 'lost wax' type of moulding technique in which the ceramic powder is compacted round a former which is subsequently removed by heating, burning or oxidation, as described in British Patents 1 360 340 and 1 443 741.
  • FIG. 4A A simpler method of fabrication is illustrated by Fig. 4A and involves the insertion if shouldered plugs 40 of partly sintered ceramic material powder into each end of a green-state parallel tube 11.
  • the powders from which the plugs are made are chosen to ensure that the tube shrinks onto them during the final sintering process and gives a vacuum tight join, as described in British Patent 1 196 899.
  • the excess 41 at the ends of the tube can be trimmed off after the final sintering.
  • End caps 14 are sealed to the respective end portions 12 through the intermediary of a sealing composition 15.
  • the caps carry conductive electrode supports 16 terminating in arc tube electrodes 17, which may be of conventional type but preferably have a double overwind of tungsten wire (see Fig. 5), lccated in shouldered portions 13.
  • the end closures 14 carry external electrical leads 18 which are preferably connected electrically to the supports 16 through conductive cermet material constituting or included in the end closure 14 as described in our German Specification 26 55 726.
  • the sealing composition 15 may be a halide resistant sealing glass, in which case the cemet closure, the intermediary sealing material and the end of the tube are heated to a temperature sufficient to cause the glass to soften and flow over the surfaces to be sealed. Application of light pressure helps to seal the cermet squarely on the tube end.
  • the sealing composition may be a ceramic material based, for example, on an oxide such as alumina, which can be fired, ground and pressed to form an annular sealing element for application to the tube ends, as described in the British Applications referred to
  • the lower end of the arc tube may be supported in a metallic holder, for example of copper, during the sealing process, which has the effect of conducting heat away from the tube end and thereby further reducing heating of the doses of volatile substances.
  • the position of these doses in L he tube end is shown in Fig. 5, where the reference numerals correspond to those in Fig. 1.
  • the cermet closure 14 differs from that in Fig. 1 in having a boss 42, on which the doses 43 rest during the operation of sealing the second tube end.
  • the electrodes 17 have the double tungsten overwind already referred to.
  • the end portions 12 of reduced cross-section and more especially the closures 14 of. corresponding reduced cross-section reduce the radiative thermal losses from the tube ends and enable a relatively high spot temperature to be maintained. Furthermore, this structure of arc tube reduces the transfer of heat to dosed materials within the tube during the operation of sealing on the final end closure 14.
  • the arc tube 20 of Fig. 2 includes a central portion 21 of enlarged diameter which tapers towards both ends in regions 22 to terminal orifices 23 of reduced diameter. The ends are closed by cermet end caps 24 with the help of sealing material 25 and are provided with electrodes 26 and external electrical connections 27 as in the lamp of Fig. 1.
  • the materials and techniques employed in the manufacture of this lamp may be the same as for the lamp of Fig. 1, and the tube may be either machined from a solid piece or moulded by the 'lost wax' process.
  • the shape of the arc tube shown in Fig. 2 enables a more nearly isothermal temperature distribution to be maintained along the length of the tube during lamp operation.
  • the reduced diameter of the ends 23 and closures 24 have the same advantages as in the lamp of Fig. 1.
  • an arc tube 30 is substantially cylindrical throughout the greater part of its length but at its ends has shouldered regions 31 providing terminal orifices 32 of reduced diameter.
  • the tube is closed by suitably shaped end plugs 33 which are sealed to the orifices 32 with the help of sealing material 34.
  • Electrodes 35 are carried on very short supports or shanks and external electrical connections 36 are provided.
  • the tube 30 together with the shouldered regions 31 can be made by the 'lost wax' moulding process or, more simply, by inserting shaped and apertured end plugs 44 into the ends of a green-state tube prior to final sintering, as shown in Fig. 4B. After sintering, the ends can be trimmed and the external shoulder ground to a radius to follow the internal curvature.
  • the end plugs 33 In sealing the end plugs 33 to the ends of the arc tube 30, considerably greater pressure has to be applied to the cermet.
  • the end plugs are preferably sealed to the tube 30 with the help of the ceramic sealing materials and techniques described in Application 35720/78 which enable a lower sealing temperature to be employed, for example about 1200°C, while pressure is applied in the axial direction between the end plug and the arc tube.
  • the lower temperatures employed help further to reduce the transfer of heat from the region of the seal to dosed materials within the arc tube during final sealing.
  • the invention is eminently suitable for use with lower power, high efficacy, metal halide lamps.
  • the vapour fill for such lamps may be of a conventional character and thus comprise an inert gas, such as argon, mercury and at least one metal halide, as well known in the art, to provide a modified or broadened emission spectrum.
  • the halides may comprise sodium and tin halides as described in our British Patent 1 541 437 or, as an alternative, sodium and aluminium halides as described in our British Patent 1 444 023.
  • the invention is of especial interest in the production of lamps of less than 250 watts power, for example, for domestic use and more particularly below 150 watts, for example, about 100 watts.
EP79302675A 1978-12-01 1979-11-22 Elektrische Entladungslampen Withdrawn EP0011993A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB4680678 1978-12-01
GB7846806 1978-12-01

Publications (1)

Publication Number Publication Date
EP0011993A1 true EP0011993A1 (de) 1980-06-11

Family

ID=10501463

Family Applications (1)

Application Number Title Priority Date Filing Date
EP79302675A Withdrawn EP0011993A1 (de) 1978-12-01 1979-11-22 Elektrische Entladungslampen

Country Status (3)

Country Link
EP (1) EP0011993A1 (de)
JP (1) JPS5576563A (de)
AU (1) AU5329379A (de)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1995028732A1 (en) * 1994-04-13 1995-10-26 Philips Electronics N.V. High-pressure metal halide lamp
US5592049A (en) * 1993-02-05 1997-01-07 Patent-Treuhand-Gesellschaft Fuer Elektrische Gluehlampen Mbh High pressure discharge lamp including directly sintered feedthrough
WO1997032334A1 (en) * 1996-02-28 1997-09-04 Philips Electronics N.V. Metal halide lamp
EP0954007A1 (de) * 1997-01-18 1999-11-03 Toto Ltd. Entladungslampe verfahren und vorrichtung zur abdichtung einer entladungslampe
EP0912993B1 (de) * 1997-04-09 2004-08-18 Koninklijke Philips Electronics N.V. Metallhalogenidlampe

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5914245A (ja) * 1982-07-14 1984-01-25 Ngk Insulators Ltd 高圧放電灯用セラミツク発光管
JPS6037645A (ja) * 1983-08-10 1985-02-27 Toshiba Corp 金属蒸気放電灯
JPS6081757A (ja) * 1983-10-11 1985-05-09 Toshiba Corp 金属蒸気放電灯
JPH01186545A (ja) * 1988-08-13 1989-07-26 Ngk Insulators Ltd 高圧放電灯用セラミック発光管

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL6701941A (de) * 1967-02-09 1968-08-12
NL7005546A (de) * 1969-04-18 1970-10-20
DE2152888A1 (de) * 1970-10-27 1972-05-04 Westinghouse Electric Corp Bogenentladungs-Rohrkörper und Verfahren zu dessen Herstellung
NL7202270A (de) * 1972-02-21 1973-08-23 Philips Nv
DE2401947A1 (de) * 1973-01-17 1974-07-25 Itt Ind Gmbh Deutsche Entladungslampe und verfahren zur herstellung derselben
NL7309859A (nl) * 1973-07-04 1975-01-20 Nikex Nehezipari Kulkere Werkwijze voor de vervaardiging van lichtdoorla- tende, compacte polykristallijnealuminiumoxyde-sintervoowerpen in het bijzonder voor lichtbuizen.
US3907949A (en) * 1970-10-27 1975-09-23 Westinghouse Electric Corp Method of making tubular polycrystalline oxide body with tapered ends
NL7613722A (nl) * 1975-12-09 1977-06-13 Thorn Electrical Ind Ltd Cermetten, de vervaardiging en de toepassing daarvan.
NL7608688A (nl) * 1976-08-05 1978-02-07 Philips Nv Samengesteld lichaam.

Patent Citations (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH471465A (de) * 1967-02-09 1969-04-15 Philips Nv Längliche Hochdruck-Quecksilberdampfentladungslampe
NL6701941A (de) * 1967-02-09 1968-08-12
NL7005546A (de) * 1969-04-18 1970-10-20
DE2017854A1 (en) * 1969-04-18 1970-11-19 Seals between sintered ceramic parts
DE2152888A1 (de) * 1970-10-27 1972-05-04 Westinghouse Electric Corp Bogenentladungs-Rohrkörper und Verfahren zu dessen Herstellung
US3907949A (en) * 1970-10-27 1975-09-23 Westinghouse Electric Corp Method of making tubular polycrystalline oxide body with tapered ends
GB1382934A (en) * 1972-02-21 1975-02-05 Philips Electronic Associated Highpressure discharge lamp having a metal lead-through conductor
NL7202270A (de) * 1972-02-21 1973-08-23 Philips Nv
DE2307192A1 (de) * 1972-02-21 1973-08-30 Philips Nv Hochdruckentladungslampe mit einem metallenen durchfuehrungsleiter
FR2173092A1 (de) * 1972-02-21 1973-10-05 Philips Nv
DE2401947A1 (de) * 1973-01-17 1974-07-25 Itt Ind Gmbh Deutsche Entladungslampe und verfahren zur herstellung derselben
NL7309859A (nl) * 1973-07-04 1975-01-20 Nikex Nehezipari Kulkere Werkwijze voor de vervaardiging van lichtdoorla- tende, compacte polykristallijnealuminiumoxyde-sintervoowerpen in het bijzonder voor lichtbuizen.
NL7613722A (nl) * 1975-12-09 1977-06-13 Thorn Electrical Ind Ltd Cermetten, de vervaardiging en de toepassing daarvan.
FR2334644A1 (fr) * 1975-12-09 1977-07-08 Thorn Electrical Ind Ltd Cermets et procede pour leur fabrication
NL7608688A (nl) * 1976-08-05 1978-02-07 Philips Nv Samengesteld lichaam.
DE2734015A1 (de) * 1976-08-05 1978-02-09 Philips Nv Zusammengesetzter koerper
FR2360535A1 (fr) * 1976-08-05 1978-03-03 Philips Nv Corps compose

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5592049A (en) * 1993-02-05 1997-01-07 Patent-Treuhand-Gesellschaft Fuer Elektrische Gluehlampen Mbh High pressure discharge lamp including directly sintered feedthrough
US5810635A (en) * 1993-02-05 1998-09-22 Patent-Treuhand-Gesellschaft Fuer Elektrische Gluehlampen Mbh High-pressure discharge lamp, method of its manufacture, and sealing material used with the method and the resulting lamp
WO1995028732A1 (en) * 1994-04-13 1995-10-26 Philips Electronics N.V. High-pressure metal halide lamp
AU687174B2 (en) * 1994-04-13 1998-02-19 Koninklijke Philips Electronics N.V. High-pressure metal halide lamp
US5751111A (en) * 1994-04-13 1998-05-12 U.S. Philips Corporation High-pressure metal halide lamp
WO1997032334A1 (en) * 1996-02-28 1997-09-04 Philips Electronics N.V. Metal halide lamp
EP0954007A1 (de) * 1997-01-18 1999-11-03 Toto Ltd. Entladungslampe verfahren und vorrichtung zur abdichtung einer entladungslampe
EP0954007A4 (de) * 1997-01-18 2000-07-19 Toto Ltd Entladungslampe verfahren und vorrichtung zur abdichtung einer entladungslampe
EP0912993B1 (de) * 1997-04-09 2004-08-18 Koninklijke Philips Electronics N.V. Metallhalogenidlampe

Also Published As

Publication number Publication date
AU5329379A (en) 1980-06-05
JPS5576563A (en) 1980-06-09

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

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Owner name: THORN EMI LIMITED

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Inventor name: BROWN, KENNETH EDWARDTHORN LIGHTING LIMITED

Inventor name: CHALMERS, ALAN GEORGETHORN LIGHTING LIMITED