EP0926700B1 - Electrode for a high pressure discharge lamp - Google Patents

Electrode for a high pressure discharge lamp Download PDF

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Publication number
EP0926700B1
EP0926700B1 EP98310549A EP98310549A EP0926700B1 EP 0926700 B1 EP0926700 B1 EP 0926700B1 EP 98310549 A EP98310549 A EP 98310549A EP 98310549 A EP98310549 A EP 98310549A EP 0926700 B1 EP0926700 B1 EP 0926700B1
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EP
European Patent Office
Prior art keywords
electrode
vessel
current conductor
composite electrode
mixture
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
EP98310549A
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German (de)
English (en)
French (fr)
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EP0926700A2 (en
EP0926700A3 (en
Inventor
Norikazu Niimi
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NGK Insulators Ltd
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NGK Insulators Ltd
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Priority claimed from US08/998,311 external-priority patent/US6169366B1/en
Application filed by NGK Insulators Ltd filed Critical NGK Insulators Ltd
Publication of EP0926700A2 publication Critical patent/EP0926700A2/en
Publication of EP0926700A3 publication Critical patent/EP0926700A3/en
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    • 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
    • H01J9/022—Manufacture of electrodes or electrode systems of cold cathodes
    • 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
    • H01J61/0732—Main electrodes for high-pressure discharge lamps characterised by the construction of the electrode
    • 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
    • H01J61/366—Seals for leading-in conductors

Definitions

  • the present invention relates to a composite electrode for a high pressure discharge lamp, such as a high pressure sodium light-emitting lamp, a metal halide lamp.
  • such a high pressure discharge lamp comprises a vessel made of a non-conductive material (e.g. alumina) which forms an inner space filled with an ionizable light-emitting material and a starting gas, and which has opening portions at the ends thereof.
  • the high pressure discharge lamp also comprises a composite electrode having a substantially cylindrical current conductor made of a conductive material (e.g. molybdenum) with a diameter which is substantially same as that of the opening portion at one end of the vessel, and an electrode electrically connected to the current conductor. In this instance, a gap between the current conductor and the vessel is tightly sealed.
  • JP-A-2-132750 discloses a high pressure discharge lamp wherein, instead of forming the current conductor with only conductive material, the current conductor comprises a substantially cylindrical non-conductive material (e.g. alumina), which is same as that forming the vessel and coated by tungsten with a substantially uniform thickness over the surface of the non-conductive material.
  • the composite electrode is composed such that a concave portion is provided at the bottom of the current conductor and an electrode is buried in the concave portion, or the electrode is connected to the current conductor with another member such as a cap.
  • the vessel and the composite electrode have been subjected to a co-firing into an integrated body, with the current conductor inserted into the opening portion at one end of the vessel so that the electrode is exposed to the inner space with one end of the composite electrode exposed to outside of the vessel.
  • the current conductor inserted into the opening portion at one end of the vessel so that the electrode is exposed to the inner space with one end of the composite electrode exposed to outside of the vessel.
  • JP-A-7-211292 discloses a high pressure discharge lamp wherein the current conductor comprises a substantially cylindrical non-conductive material, which is the same as that forming the vessel, and covered by a layer of mixture of platinum and alumina, a layer of platinum, and a layer of a mixture of platinum and alumina, with a substantially uniform thickness and one above the other over the surface of the non-conductive material.
  • the composite electrode is composed such that a concave portion is provided at the bottom of this current conductor and an electrode is buried in the concave portion, or the electrode is connected to the current conductor with another member such as a cap. Therefore, the adverse influence of the difference in the coefficient of thermal expansion between the conductive material and the non-conductive material is made substantially insignificant.
  • JP-A-8-273616 discloses a high pressure discharge lamp wherein the current conductor is formed with the substantially cylindrical non-conductive material, which is the same as that forming the vessel material, and covered by a halide-resistant metal such as niobium, tungsten, etc., with a substantially uniform thickness over the surface of the non-conductive material.
  • the composite electrode is also composed such that a concave portion is provided at the bottom of this current conductor and an electrode is buried in the concave portion, or the electrode is connected to the current conductor with another member such as a cap. Therefore, the adverse influence of the difference in the coefficient of thermal expansion between the conductive material and the non-conductive material is made substantially insignificant.
  • the composite electrode having the current conductor metallized with tungsten whose melting point (3400°C) is higher than that of alumina (2015°C)
  • the melting point of tungsten in metallization is much different from that of alumina in metallization, so that the firing speed of tungsten is different from that of alumina.
  • the mutual wetting property of tungsten and aluminum is poor, and it is thus difficult to form a tightly metallized layer. Therefore, such a high pressure discharge lamp does not have fully gas-tight property.
  • the vessel and the composite electrode are not co-fired into an integrated body at least at one end of the vessel.
  • a stronger junction cannot be formed between the non-conductive material of the vessel and metallized layer on the composite electrode, as compared to an arrangement wherein the vessel and the composite electrode are co-fired into an integrated body. Therefore, such a high pressure discharge lamp does not have fully gas-tight property, either.
  • the composite electrodes for the high pressure discharge lamps disclosed in JP-A-2-132750, JP-A-7-211292 and JP-A-8-273616 it is preferred that the composite electrode can be easily manufactured and has a uniform thickness of the metallized layer over the surface of the current conductor.
  • the proximity of the opening portion at one end of the vessel is heated to a predetermined temperature (e.g. 1500°C).
  • a predetermined temperature e.g. 1500°C
  • the other end of the vessel is cooled in order to prevent the molecular movement of the ionizable light-emitting material and starting gas from being active such that they are prevented from leakage through the frit seal of the vessel to outside of the vessel.
  • the inner part of the vessel is still heated to a substantial temperature (e.g. 300 - 400°C) even for a limited period (e.g. 1-3 minutes).
  • a limited period e.g. 1-3 minutes
  • the composite electrode by jointing the electrode to the current conductor, it is preferable to have a high bonding strength between the electrode and the current conductor, a high corrosion resistance, and a high conductivity.
  • EP-A-0807957 describes a high pressure discharge lamp having a ceramic discharge tube with openings at both ends.
  • a plugging member is at least partially fixed in each end.
  • a conductive member made of conductive material is provided through the plugging member and gas-tightly joined to it by a metallising layer.
  • An electrode is provided on the end of the conductive member that lies inside the discharge tube.
  • a high pressure discharge lamp comprises a vessel made of a non-conductive material which forms an inner space filled with an ionizable light-emitting material and a starting gas, and has opening portions at both ends thereof; and a composite electrode according to the invention, wherein the cylindrical member has a diameter which is substantially the same as a diameter of the opening portion at one end of the vessel.
  • said non-conductive material of the mixture contains not less than 50 vol. % of a material which is the same as that forming said vessel.
  • said vessel and said composite electrode are subjected to a co-firing into an integrated body, with the composite electrode inserted into the opening portion at one end of the vessel so that the electrode is exposed to the inner space with one end of the composite electrode is exposed to outside of the vessel.
  • the non-conductive material in the vessel and the substantially cylindrical member is diffused into the layer of the mixture formed on a surface of the substantially cylindrical member so that a strong joining structure is formed between the vessel and the substantially cylindrical member.
  • the metal of the mixture coated on at least a tubular surface thereof the substantially cylindrical member to contain a metal which has melting point comparatively close to those of the nearly cylindrical member and the vessel, etc, and has enough halide resistance, and for its non-conductive material to contain a material which is the same as that forming the vessel and the substantially cylindrical member.
  • the metal of the mixture coated on at least a tubular surface of the substantially cylindrical member contains not less than 50 vol.% of molybdenum which has halide resistance and lower melting point (2623°C) than that of tungsten, and the non-conductive material of the mixture coated on the substantially cylindrical member contains not less than 50 vol.% of a material which is the same as that forming the vessel.
  • a high pressure discharge lamp has fully tight property while maintaining fully conductivity.
  • a substantially cylindrical member is understood to mean not only a cylindrical member itself but also a member in which a concave portion is provided at the bottom of the cylindrical member and a member in which the bottom of the cylindrical member is inclined to an axis thereof as described hereinafter.
  • the content of said metal of the mixture coated on said substantially cylindrical member is 30 to 70 vol.%.
  • the conductivity of the high pressure discharge lamp improves.
  • the content of the non-conductive material of the mixture becomes high, the tight property of the high pressure discharge lamp improves.
  • preferable content of the metal of the mixture is 30 to 70 vol.%.
  • said metal of the mixture coated on said substantially cylindrical member is made of molybdenum
  • said non-conductive material of the mixture is made of a material which is same as that forming said vessel.
  • the content of molybdenum in the metal of the mixture coated on at least a tubular surface of the substantially cylindrical member is as high as possible, and the content of the material which is the same as that forming the vessel in the non-conductive material of the mixture is as high as possible. Therefore, it is the most suitable for the mixture to compose of molybdenum and the material which is the same as that forming the vessel.
  • molybdenum is understood to mean not only pure molybdenum but also that containing a little impurities, and the material which is the same as that forming the vessel is understood to mean not only completely same as that forming the vessel but also that containing a little impurities.
  • a high pressure discharge lamp comprises vessel made of a non-conductive material which forms an inner space filled with an ionizable light-emitting material and a starting gas, and has opening portions at both ends thereof; and a composite electrode according to the invention, wherein the cylindrical member has a diameter which is smaller than a diameter of the opening portion at one end of the vessel.
  • the current conductor of the composite electrode and said vessel are so arranged relative to each other as to leave a gap therebetween, with the composite electrode inserted into the opening portion at one end of the vessel so that the electrode is exposed to the inner space and one end of the composite electrode is exposed to outside of the vessel, said gap being tightly sealed with a metallic layer or a layer made of a mixture of a metal and a material which is the same as that forming said vessel.
  • a high pressure discharge lamp comprises a vessel made of a non-conductive material which forms an inner space filled with an ionizable light-emitting material and a starting gas, and has opening portions at both ends thereof; a first composite electrode according to the invention having a current conductor with a diameter which is substantially same as a diameter of the opening portion at one end of the vessel; and a second composite electrode according to the invention having a current conductor with a diameter which is smaller than a diameter of the opening portion at the other end of the vessel; said vessel and said first composite electrode having been subjected to a co-firing into an integrated body, with the first composite electrode inserted into the opening portion at one end of the vessel so that the electrode is exposed to the inner space with one end of the first composite electrode is exposed to outside of the vessel; and said current conductor of the second composite electrode and said vessel being so arranged relative to each other as to leave a gap therebetween, with the second composite electrode inserted into the opening portion at the other end of the vessel so that the electrode is
  • the high pressure discharge lamp according to this embodiment has a fully tight property while maintaining fully conductivity.
  • the gap may be tight sealed with such a layer, it may be tight sealed with the frit seal as usual.
  • a high pressure discharge lamp comprises a vessel made of a non-conductive material which forms an inner space filled with an ionizable light-emitting material and a starting gas, and has opening portions at both ends thereof; and a composite electrode according to the invention having a cylindrical current conductor with a diameter which is substantially same as a diameter of the opening portion at one end of the vessel, wherein the electrode is joined by welding or metallizing at a bottom or a side of the current conductor exposed to inside of the vessel.
  • the electrode is jointed by welding or metallizing at a bottom or a side of the current conductor which is formed by a cylindrical member coated with a mixture of a metal and a non-conductive material on at least a tubular surface thereof, it is possible to coat the mixture of the metal and the non-conductive material over a surface of the current conductor with more uniform thickness than the case where the electrode is buried on the concave portion at the bottom of this current conductor, and it is possible to compose the composite electrode simpler than the case where another member such as a cap is provided.
  • a bonding area between the current conductor and the electrode or an area contacting the mixture to the current conductor and the electrode increases, so that the bonding strength between the current conductor and the electrode can further improve.
  • At least one end of the current conductor exposed to the inside of the vessel is rounded, the electrode is jointed by metallizing at the rounded end.
  • an area contacting the mixture to the current conductor is wider than the case where the rounded end is not provided, so that the bonding strength between the current conductor and the electrode can improve much more. Also, as an area which contacts the mixture using the joint of the current conductor and the electrode to the mixture coated on the cylindrical member increases, the conductivity of the composite electrode become higher. Moreover, such a rounded end prevents from a stress concentration at the proximity of the end.
  • a metal or a mixture of a metal and a non-conductive material having a higher melting point and/or a higher corrosion resistance than the metal or mixture of metal and non-conductive material which joins the electrode and the current conductor is coated on the join between the electrode and the current conductor and the proximity thereof.
  • the bonding strength between the current conductor and the electrode and/or the corrosion resistance further improves.
  • At least one end of the current conductor exposed to the inside of the vessel is rounded, the electrode is jointed by metallizing at the rounded end, a metal or a mixture of a metal and a non-conducting material having a higher melting point and/or a higher corrosion resistance than a metal or a mixture of a metal and a non-conductive material jointing the electrode and the current conductor is coated on the joint portion of the electrode and the current conductor and the proximity thereof.
  • the composite electrode may have a cylindrical current conductor with a diameter which is smaller than a diameter of the opening portion at one end of the vessel, said current conductor and said vessel being so arranged relative to each other as to leave a gap therebetween, with the composite electrode inserted into the opening portion at one end of the vessel so that the electrode is exposed to the inner space and one end of the composite electrode is exposed to outside of the vessel, said gap being tightly sealed with a metallic layer or a layer made of a mixture of a metal and a material which is same as that forming said vessel.
  • the ionizable light-emitting material and the starting gas may not leak to outside of the vessel.
  • a high pressure discharge lamp comprises a vessel made of a non-conductive material which forms an inner space filled with an ionizable light-emitting material and a starting gas, and has opening portions at both ends thereof; a first composite electrode according to the invention having a cylindrical current conductor with a diameter which is substantially same as a diameter of the opening portion at one end of the vessel, the electrode being joined by welding or metallizing at a bottom of the current conductor exposed to inside of the vessel; and a second composite electrode according to the invention having a cylindrical current conductor with a diameter which is smaller than a diameter of the opening portion at the other end of the vessel, the electrode being joined by welding or metallizing at a bottom or a side of the current conductor exposed to inside of the vessel; said vessel and said first composite electrode having been subjected to a co-firing into an integrated body, with the first composite electrode inserted into the opening portion at one end of the vessel so that the electrode is exposed to the inner space with one end of the first composite electrode is exposed to
  • the high pressure discharge lamp according to this embodiment has a fully tight property while maintaining fully conductivity.
  • tight sealing may be effected with a frit seal as usual.
  • the electrode is jointed by welding or metallizing at a bottom or a side of the current conductor which is formed by a cylindrical member coated with a mixture of a metal and a non-conductive material on at least a tubular surface thereof, the advantages and optional features described above are available.
  • the composite electrode may include a substantially cylindrical current conductor with a bottom inclined to an axis thereof.
  • the electrode may be joined by welding or metallizing to the inclined bottom.
  • an area contacting the mixture to the current conductor is larger than the case where the electrode is jointed at a bottom of the current conductor whose bottom is perpendicular to an axis thereof, so that the bonding strength between the electrode and the current conductor improves.
  • At least one end of the current conductor exposed to inside of the vessel is rounded, the electrode is jointed by metallizing at the rounded end.
  • the composite electrode may have a substantially cylindrical current conductor with a diameter which is smaller than or the same as a diameter of the opening portion at one end of a vessel with which it forms a high pressure discharge lamp.
  • a high pressure discharge lamp may include a first composite electrode having a diameter which is substantially same as a diameter of the opening portion at one end of the vessel and a bottom inclined to an axis thereof and a second composite electrode having a diameter which is smaller than a diameter of the opening portion at the other end of the vessel and a bottom inclined to an axis thereof exposed to inside of the vessel.
  • an area contacting the mixture to the current conductor is larger than the case where the electrode is joined at a bottom of the current conductor whose bottom is perpendicular to an axis thereof, so that the bonding strength between the electrode and the current conductor improves.
  • an axis of the electrode to substantially correspond to that of an electrode to be opposite to the electrode. According to the invention, as an axis of the electrode substantially corresponds to that of an electrode to be opposite to the electrode, it is possible to do good ignition of the high pressure discharge lamp.
  • a method of manufacturing a high pressure discharge lamp comprises the steps of: forming a vessel made of a non-conductive material formed with an inner space filled with an ionizable light-emitting material and a starting gas, and with opening portions at the ends of the inner space; and forming a composite electrode which has a current conductor formed by a substantially cylindrical member coated with a mixture of a metal and a non-conductive material on at least a tubular surface thereof and an electrode electrically connected to the current conductor; said metal of the mixture coating on the substantial cylindrical member containing not less than 50 vol.% of molybdenum, said non-conductive material of the mixture containing not less than 50 vol.% of a material which is the same as that forming said vessel, and said substantially cylindrical current conductor has substantially same diameter as a diameter of the opening portion at one end of the vessel; inserting said composite electrode into the opening portion at one end of the vessel such that the electrode is exposed to the inner space and one end of the composite electrode is exposed to outside of the vessel, and co-firing said
  • the high pressure discharge lamp according to the invention have fully tight property while maintaining fully conductivity.
  • the substantially cylindrical current conductor may have a smaller diameter than a diameter of the opening portion at one end of the vessel, said current conductor and said vessel being so arranged relative to each other as to leave a gap therebetween, said gap being tightly sealed with a metallic layer or a layer made of a mixture of a metal and a material which is the same as that forming said vessel.
  • the method includes the steps of:
  • the gap may be tight sealed with a frit seal as usual.
  • the electrode is joined by welded or metallizing at a bottom or a side of the current conductor.
  • the electrode is jointed by welding or metallizing at a bottom or a side of the current conductor which is formed by a cylindrical member coated with a mixture of a metal and a non-conductive material on at least a tubular surface thereof, it is possible to coat the mixture of the metal and the non-conductive material over a surface of the current conductor with more uniform thickness than the case where the electrode is buried on the concave portion at the bottom of this current conductor, and it is possible to compose the composite electrode simpler than the case where another member such as a cap is provided.
  • At least one end of the current conductor is rounded, the electrode is jointed by metallizing at the rounded end.
  • an area contacting the mixture to the current conductor is wider than the case where the rounded end is not provided, so that the bonding strength between the current conductor and the electrode can further improve. Also, as an area which contacts the mixture using the joint of the current conductor and the electrode to the mixture coated on the cylindrical member increases, the conductivity of the composite electrode become higher. Moreover, such a rounded end prevents from a stress concentration at the proximity of the end.
  • the electrode is jointed by welding or metallizing at a side of the current conductor, a metal or a mixture of a metal and a non-conductive material having a higher melting point and/or a higher corrosion resistance than a metal or a mixture of a metal and a non-conductive material jointing the electrode and the current conductor is coated on the joint portion of the electrode and the current conductor and the proximity thereof.
  • the bonding strength between the current conductor and the electrode and/or the corrosion resistance further improves.
  • the cylindrical member coated with a mixture of a metal and a non-conductive material may have a bottom inclined to an axis thereof.
  • the electrode may be joined by welding or metallizing to the inclined bottom;
  • an area contacting the mixture to the current conductor is wider than the case where the electrode is jointed at a bottom of the current conductor whose bottom is perpendicular to an axis thereof, so that the bonding strength between the electrode and the current conductor improves.
  • At least one end of the current conductor is rounded, the electrode is jointed by metallizing at the rounded end.
  • the electrode is joined by welding or metallising only at a side of the current conductor.
  • an area contacting the mixture to the current conductor is larger than the case where the electrode is jointed at a bottom of the current conductor whose bottom is perpendicular to an axis thereof, so that the bonding strength between the electrode and the current conductor improves.
  • an axis of the electrode substantially corresponds to that of an electrode to be opposite to the electrode, it is possible to do good ignition of the high pressure discharge lamp.
  • the electrode is jointed by welding or metallizing at a side of the current conductor exposed to inside of the vessel, a metal or a mixture of a metal and a non-conductive material having a higher melting point and/or a higher corrosion resistance than a metal or a mixture of a metal and a non-conductive material jointing the electrode and the current conductor is coated on the joint portion of the electrode and the current conductor and the proximity thereof.
  • the method of manufacturing a composite electrode for a high pressure discharge lamp comprises the steps of: forming a current conductor made of a cylindrical member coated with a mixture of a metal and a non-conductive material on at least a tubular surface thereof, and an electrode joined to a bottom or a side of the current conductor, said metal of the mixture coating on the cylindrical member containing not less than 50 vol. % of molybdenum, and said non-conductive material of the mixture containing not less than 50 vol.% of a material which is the same as that forming said vessel.
  • the electrode may be joined by welding or metallizing at a bottom or a side of the current conductor which is formed by a cylindrical member coated with a mixture of a metal and a non-conductive material on at least a tubular surface thereof to this case, it is possible to coat the mixture of the metal and the non-conductive material over a surface of the current conductor with more uniform thickness than the case where the electrode is buried on the concave portion at the bottom of this current conductor, and it is possible to compose the composite electrode simpler than the case where another member such as a cap is provided.
  • At least one end of the current conductor is rounded, the electrode is jointed by metallizing at the rounded end.
  • an area contacting the mixture to the current conductor is wider than the case where the rounded end is not provided, so that the bonding strength between the current conductor and the electrode can further improve. Also, as an area which contacts the mixture using the joint of the current conductor and the electrode to the mixture coated on the cylindrical member increases, the conductivity of the composite electrode become higher. Moreover, such a rounded end prevents from a stress concentration at the proximity of the end.
  • the electrode is jointed by welding or metallizing at a side of the current conductor, a metal or a mixture of a metal and a non-conductive material having a higher melting point and/or a higher corrosion resistance than a metal or a mixture of a metal and a non-conductive material jointing the electrode and the current conductor is coated on the joint portion of the electrode and the current conductor and the proximity thereof.
  • the bonding strength between the current conductor and the electrode and/or the corrosion resistance further improves.
  • the cylindrical member has a bottom inclined to an axis thereof;
  • a bonding strength between the current conductor and the electrode is higher than the case the electrode is joined at a bottom perpendicular to an axis thereof.
  • At least one end of the current conductor is rounded, the electrode is jointed by metallizing at the rounded end.
  • the electrode is joined at a side of the current conductor so that an axis of the electrode substantially matches with that of an electrode to be opposite to the electrode.
  • an axis of the electrode substantially corresponds to that of an electrode to be opposite to the electrode, it is possible to do good ignition of the high pressure discharge lamp.
  • the electrode is jointed by welding or metallizing at a side of the current conductor exposed to inside of the vessel, a metal or a mixture of a metal and a non-conductive material having a higher melting point and/or a higher corrosion resistance than a metal or a mixture of a metal and a non-conductive material jointing the electrode and the current conductor is coated on the joint portion of the electrode and the current conductor and the proximity thereof.
  • the bonding strength between the current conductor and the electrode and/or the corrosion resistance further improves.
  • an external lead; etc Mo, Ni, etc
  • an external lead; etc Mo, Ni, etc
  • Fig. 1 is a view showing first embodiment of the invention.
  • a ceramic tube 2 is accommodated within a outer tube 1 made of a quartz glass or a hard glass, and the center axis of the outer tube 1 is aligned with that of the ceramic tube 2.
  • Both ends of the outer tube 1 are gas-tightly sealed with caps 3a, 3b, respectively.
  • the ceramic tube 2 comprises a tubular vessel 4 made of a alumina, first composite electrode 6a, 6b inserted into opening portions of ends portions 5a, 5b of the tubular vessel 4, respectively.
  • the ceramic discharge lamp is held by the outer tube 2 via two lead wires 7a, 7b, and the lead wires 7a, 7b are connected to the caps 3a, 3b via foil 8a, 8b, respectively.
  • Fig. 2 is a sectional view for showing, in an enlarged scale, surrounding area around an end portion 5a of a ceramic discharge tube 2 in Fig. 1.
  • the vessel 4 has a main body 10 and a plugging member made of an alumina.
  • the first composite electrode 6a has a cylindrical current conductor 13a with a diameter which is substantially same as a diameter of the opening portion of the plugging member 11a, and a electrode 14a jointed by welding at a bottom of the current conductor 13a exposed to inside of the vessel 4.
  • the electrode 14a has a coil 15a.
  • the first composite electrode 6a has a cylindrical member, and a metallizing layer composed of a mixture of a molybdenum and a alumina.
  • a diagram representing the transition of alumina and molybdenum concentrations in the cylindrical member, the metallized layer and the vessel 4 is shown in Fig. 3.
  • the ceramic discharge tube (Fig. 1) is composed such that the vessel 4 and the first composite electrode 6a have been subjected to a co-firing into an integrated body, with the first composite electrode 6a inserted into the opening portion at one end of the vessel 4 so that the electrode 14 is exposed to the inner space with one end of the first composite electrode 6a is exposed to outside of the vessel 4.
  • Fig. 4B is a sectional view for showing, in an enlarged scale, surrounding area around an end portion 5b of a ceramic discharge tube 2 in Fig. 1, and Fig. 4B is a partial enlarged view of the sectional view in Fig. 4A.
  • the vessel 4 has a plugging member 11b made of the alumina and a capillary 16.
  • the second composite electrode 6b has a cylindrical current conductor 13b with a diameter which is smaller than a diameter of the opening portion of the plugging member 11b, and a electrode 14b jointed by welding at a bottom of the current conductor 13b exposed to inside of the vessel 4.
  • the electrode 14b has a coil 15b. Further, a gap between the second composite electrode 6b and the capillary 16 is tightly sealed with a frit seal 17.
  • the current conductor 13b of the second composite electrode 6b has a cylindrical member, and a metallizing layer composed of a mixture of a molybdenum and a alumina.
  • a diagram representing the transition of alumina and molybdenum concentrations in the cylindrical member, the metallized layer and the vessel 4 is shown in Fig. 5.
  • the high pressure discharge lamp have fully tight property while fully conductivity.
  • the electrodes 15a, 15b are jointed by welding at the bottom of the current conductors 13a, 13b which is formed by a cylindrical member coated with the mixture of the molybdenum and alumina, respectively, it is possible to coat the mixture of the metal and alumina over a surface of the current conductor with more uniform thickness than the case where the electrode is buried in a concave portion at the bottom of the current conductor, and it is possible to compose the composite electrode simpler than the case where another member such as a cap is provided.
  • Fig. 6B is a sectional view for showing, in an enlarged scale, surrounding area around an end portion of a ceramic discharge tube in accordance with the first embodiment of the invention and Fig. 6B is a partial enlarged view of the sectional view thereof.
  • a barrel-shaped vessel can be used as the vessel, and a composite electrode which has a electrode buried in a concave portion at the bottom of a current conductor can be used as the first composite electrode.
  • a composite electrode which has a electrode buried in a concave portion at the bottom of a current conductor can be used as the second composite electrode. Further, in this case, as described after, a gap between the opening of the capillary and the current conductor is tightly sealed with the molybdenum or the mixture of the molybdenum and the alumina.
  • Fig. 7 is a view for showing a second embodiment of the high pressure discharge lamp in accordance with the invention
  • Fig. 8 is a view for describing the gas-tight sealing at one end of a ceramic discharge tube for a high pressure discharge lamp. Further, in Fig. 8, as an end portion 5c has a construction which is the same as that of an end portion 5d, only the end portion 5c is described.
  • the vessel 4 has the main body 10, a plugging member made of the alumina, and a capillary 16c .
  • a composite electrode 6c has a cylindrical current conductor 13c with a diameter which is smaller than a diameter of the opening portion of the plugging member 11c, and a electrode 14c jointed by welding at a bottom of the current conductor 13c exposed to inside of the vessel 4.
  • the electrode 14c has a coil 15c. Further, a gap between the second composite electrode 6c and the capillary 16c is tightly sealed by welding.
  • the current conductor 13b of the second composite electrode 6b has the cylindrical member, and the metallizing layer composed of the mixture of the molybdenum and the alumina.
  • an ionizable light-emitting material and a starting gas may not leak to outside of the vessel.
  • Figs. 9A to 9G show another examples at the end of the vessel in second embodiment.
  • a composite electrode which has a electrode buried in a concave portion at the bottom of a current conductor is used as the composite electrode, and a gap between the composite electrode and the opening portion is tightly sealed by welding.
  • the metallizing layer is formed, and the molybdenum is provided between the composite electrode and the capillary by brazing.
  • a layer for melting is provided between an extending conductive layer for earth and the conductive layer.
  • the capillary is not provided at the end.
  • Fig. 10A is a view showing an example of an end of a vessel which is not an embodiment of the invention, but is included for information.
  • Fig. 10B is a part of Fig. 10A in enlarged scale.
  • an electrode 21 is jointed at a metallizing coating portion 24 (which is composed of molybdenum or a mixture of molybdenum and alumina, for example) coated on the proximity of an opening portion at one end of a vessel 13 with a metallizing portion 22 composed of a mixture of a metal (molybdenum, for example) and a non-conductive material (the mixture is composed of molybdenum and alumina, for example), so that the electrode 21 electrically connects to a lead 25.
  • a metallizing coating portion 24 which is composed of molybdenum or a mixture of molybdenum and alumina, for example
  • the vessel 23 and a plug 26 made of alumina whose diameter is smaller than a diameter of the opening portion at one end of the vessel 13 are so arranged relative to each other as leave a gap therebetween, with the plug 26 inserted into the opening portion at one end of the vessel 23 filled with a light-emitting material, the gap is tightly sealed with a frit seal 27.
  • Fig. 10C is a view showing another example of an end of a vessel which is not an embodiment of the invention, and Fig. 10D is a part thereof in enlarged scale.
  • a material which has a higher melting point and/or a higher corrosion resistance than the metal or the mixture of the metal and the non-conductive material which compose of the metallizing portion 22 that material is composed of tungsten or a mixture of tungsten and alumina, for example
  • the bonding strength and/or the corrosion resistance of the electrode 21 further improve(s).
  • Fig. 10E is a view showing another example of an end of a vessel which is not an embodiment of the invention, and Fig. 10F is a part thereof in enlarged scale.
  • an electrode 31 is jointed at a metallizing coating portion 34 (which is composed of molybdenum or a mixture of molybdenum and alumina, for example) coated on the proximity of an opening portion at one end of a vessel 33 with a metallizing portion 32 composed of a mixture of a metal (molybdenum, for example) and a non-conductive material (the mixture is composed of molybdenum and alumina, for example), so that the electrode 31 electrically connects to a lead 35.
  • the vessel 33 and a plug 36 made of alumina which has a substantially same diameter as a diameter of the opening portion have been subjected to a co-firing into an integrated body, with the plug 36 at one end of the vessel 33.
  • the bonding strength of the electrode improves.
  • Fig. 10G is a view showing another example of an end of a vessel which is not an embodiment of the invention, and Fig. 10H is a part thereof in enlarged scale.
  • a material which has a higher melting point and/or a higher corrosion resistance than the metal or the mixture of the metal and the non-conductive material which compose of the metallizing portion 32 that material is composed of tungsten or a mixture of tungsten and alumina, for example
  • the bonding strength and/or the corrosion resistance of the electrode 31 further improve(s).
  • Figs. 11A to 11K are view for showing a composite electrode for a high pressure discharge lamp according to the invention.
  • a rod-shaped electrode is jointed to the current conductor by welding.
  • the rod-shaped electrode is jointed to the current conductor by metallizing.
  • an electrode having a rod-shaped portion and a disk portion is jointed to the current conductor by metallizing.
  • a rod made of a niobium is jointed to the end of the current conductor.
  • a substantially cylindrical member made of a non-conductive material (alumina, for example) which is coated with a mixture of a metal and a non-conductive material (molybdenum and alumina, for example) on only a tubular surface thereof has one bottom inclined to an axis thereof, and an electrode is jointed at the inclined bottom with the mixture.
  • an area contacting the mixture at the inclined bottom is wider than the case where a bottom thereof is perpendicular to an axis thereof provided that a diameter of the substantially cylindrical member whose bottom is inclined to an axis thereof is the same as that whose bottom is perpendicular to an axis thereof, so that the bonding strength improves.
  • a cylindrical member made of a non-conductive material (alumina, for example) is coated with a mixture of a metal and a non-conductive material (molybdenum and alumina, for example) on only a tubular surface thereof, and an electrode is jointed at a side of the cylindrical member with the mixture.
  • a non-conductive material alumina, for example
  • a non-conductive material mobdenum and alumina, for example
  • a cylindrical member made of a non-conductive material (alumina, for example) is also coated with a mixture of a metal and a non-conductive material (molybdenum and alumina, for example) on only a tubular surface thereof, and an electrode 31 is jointed at a side of the cylindrical member with the mixture.
  • a part of a pointed end portion of the electrode 31 is cut off and a pointed end portion 32 which extends so as to shift a center axis of the electrode is jointed at a side of the cylindrical member.
  • the bonding strength can be higher than the case where the electrode is jointed at a bottom of the cylindrical member.
  • such an axis of the electrode 31 can easily correspond to an axis of an electrode to be opposite to the electrode 31.
  • a cylindrical member made of a non-conductive material (alumina, for example) is also coated with a mixture of a metal and a non-conductive material (molybdenum and alumina, for example) on only a tubular surface thereof, and an electrode is jointed at a bottom of the cylindrical member with the mixture.
  • a jointing portion therebetween and the proximity thereof are coated with a material 33 having a higher melting point and/or a higher corrosion resistance than the mixture (that material is tungsten or a mixture of tungsten and alumina).
  • Fig. 11I is a part of Fig. 11H in enlarged scale. In this way, the bonding strength and/or the corrosion resistance can further improve.
  • a cylindrical member made of a non-conductive material (alumina, for example) which has a rounded end is also coated with a mixture of a metal and a non-conductive material (molybdenum and alumina, for example) on only a tubular surface thereof, and an electrode is jointed at a bottom of the cylindrical member with the mixture.
  • Fig. 11K is a part of Fig. 11J in enlarged scale.
  • a bonding strength improves
  • an area contacting the mixture for jointing to the mixture coated on the side thereof increases, the conductivity improves.
  • a material having a higher melting point and/ or a higher corrosion resistance than the mixture that material is tungsten or a mixture of tungsten and alumina
  • a material having a higher melting point and/ or a higher corrosion resistance than the mixture that material is tungsten or a mixture of tungsten and alumina
  • Table 1 a relation between vol.% of the molybdenum and that of the alumina, and those conductivity and tight property is shown in Table 1.
  • 20/80 denotes that the content of the molybdenum is 20 vol.%
  • the content of the alumina is 80 vol.%.
  • a preferable volume ratio is 30/70 to 70/30.
  • the tight property is judged with a He leak detector.
  • a preferable thickness of the metallizing layer is 20 to 400 ⁇ m.
  • the main body 10 is formed.
  • a molded body formed as such is dewaxed and calcined to obtain a calcined body.
  • an alumina powder is molded to obtain a ring shaped plugging member 11a.
  • the plugging member 11a obtained as such is dewaxed and calcined to obtain a calcined body.
  • the calcined body of the plugging member 11a is inserted into an end of the calcined body of the main body 10 to set it to a certain position, and the main body 10 and the plugging member 11a are calcined to obtain a calcined body of the vessel 4.
  • the first composite electrode 6a formed as described later is inserted into the opening portion of the plugging member 11a such that the electrode 15a is exposed to the inner space of the vessel 4 and one end of the first composite electrode 6a is exposed to outside of the vessel 4, and co-firing the vessel 4 and the first composite electrode 6a into an integrated body.
  • the second composite electrode 6b is inserted into the opening portion of the plugging member 11b such that the electrode 11b is exposed to the inner space and one end of the second composite electrode 6b is exposed to outside, and the gap between the current conductor 13b and the vessel is tightly sealed with the frit seal.
  • the main body 10 is formed.
  • a molded body formed as such is dewaxed and calcined to obtain a calcined body.
  • an alumina powder is molded to obtain a ring shaped plugging member 11c and the capillary 16c.
  • the plugging member 11c and the capillary 16c obtained as such are dewaxed and calcined to obtain calcined bodies.
  • the calcined body of the plugging member 11c is inserted into an end of the calcined body of the main body 10 to set it to a certain position
  • the calcined body of the capillary 16c is inserted into an opening portion of the plugging member 11c to set it to a certain potion
  • the main body 10 the plugging member 11c and the capillary 16c are calcined to obtain a calcined body of the vessel 4.
  • the composite electrode 6c is inserted into the opening portion of the capillary 16c such that the electrode 15c is exposed to the inner space and one end of the composite electrode 6c is exposed to outside, and the gap between the current conductor 13c and the vessel is tightly sealed with the molybdenum layer and the layer of the mixture of the molybdenum and the alumina.
  • an alumina powder is mullited and press molded to obtain a molded body, and then, the molded body is cut and processed.
  • the process is mainly outer peripheral process (centerless, etc), and the cutting can be done in advance of the processing or the processing can be done in advance of the cutting.
  • a binder is removed from the molded body, and the body is calcined by request.
  • the calcined body is applied with a paste of the alumina powder and the molybdenum powder, and the body formed as such is fired or calcined.
  • the calcined body is applied with a paste of the molybdenum powder, the body formed as such and the electrode made of the tungsten are assembled into one body, and the body is fired.
  • the composite electrode according to the invention can be manufactured in accordance with a flow chart shown in Fig. 12B.
  • the cutting and processing process is done after the firing or calcining process, the mulling of the molybdenum powder is used by required in the paste applying and assembling of the tungsten electrode process.
  • the composite electrode according to the invention can be manufactured in accordance with a flow chart shown in Fig. 12C.
  • Fig. 13 is a view for describing comparison of a prior high pressure discharge lamp and a high pressure discharge lamp according to the invention.
  • a capillary 21 coated with the metallizing layer over a surface thereof is inserted into an opening portion of a tubular member 20, and the tubular member 20 and the capillary 21 are co-fired into an integrated body.
  • the following member are used as the capillary 21.
  • Figs. 14A to 14E are photomicrographs for describing comparison of a prior high pressure discharge lamp and a high pressure discharge lamp according to the invention.
  • the photomicrographs show a portion X in Fig. 13A.
  • Fig. 14A shows that the capillary i and the tubular member 20 are co-fired into an integrated body. Judging from this, it is found that a joining structure between the capillary i and the tubular member 20 is no good.
  • Fig. 14B shows that the capillary ii and the tubular member 20 are co-fired into an integrated body. Judging from this, it is found that a joining structure between the capillary ii and the tubular member 20 is good.
  • Fig. 14C shows that the capillary iii and the tubular member 20 are co-fired into an integrated body. Judging from this, it is found that a joining structure between the capillary iii and the tubular member 20 is good.
  • Fig. 14D shows that the capillary iv and the tubular member 20 are co-fired into an integrated body. Judging from this, it is found that a joining structure between the capillary iv and the tubular member 20 is no good.
  • Fig. 14E shows that the capillary v and the tubular member 20 are co-fired into an integrated body. Judging from this, it is found that the metallizing layer is discontinuous.
  • the non-conductive material composing the vessel and the cylindrical member the another non-conductive material than the alumina (e.g. cermet) is used.
  • the metal of the mixture may contain not less than 50 vol.% of the molybdenum and the non-conductive material of the mixture may contain not less than 50 vol.% of a material which is the same as that forming the vessel (in above embodiment, alumina) .
  • the gap between the second composite electrode and the vessel when the gap between the second composite electrode and the vessel is tightly sealed, instead of using the frit seal, the gap may be tightly sealed with a layer made of the molybdenum or a layer made of the molybdenum and the alumina.
  • the main body and the plugging member are calcined with the plugging member inserted into the end of the main body, a calcined body obtained as such is fired with the composite electrode inserted into an opening portion of the calcined body.
  • the plugging member and the composite electrode are calcined with the composite electrode inserted into an opening of the plugging member, a calcined body obtained as such and the main body are fired with the calcined body inserted into the end of the main body.
  • a magnesium oxide may be added to the alumina powder.

Landscapes

  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Vessels And Coating Films For Discharge Lamps (AREA)
  • Manufacture Of Electron Tubes, Discharge Lamp Vessels, Lead-In Wires, And The Like (AREA)
  • Discharge Lamps And Accessories Thereof (AREA)
EP98310549A 1997-12-24 1998-12-22 Electrode for a high pressure discharge lamp Expired - Lifetime EP0926700B1 (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US08/998,311 US6169366B1 (en) 1997-12-24 1997-12-24 High pressure discharge lamp
US998311 1997-12-24
US09/140,587 US6407504B1 (en) 1997-12-24 1998-08-26 High pressure discharge lamp having composite electrode
US140587 1998-08-26

Publications (3)

Publication Number Publication Date
EP0926700A2 EP0926700A2 (en) 1999-06-30
EP0926700A3 EP0926700A3 (en) 1999-12-08
EP0926700B1 true EP0926700B1 (en) 2006-03-15

Family

ID=26838318

Family Applications (1)

Application Number Title Priority Date Filing Date
EP98310549A Expired - Lifetime EP0926700B1 (en) 1997-12-24 1998-12-22 Electrode for a high pressure discharge lamp

Country Status (6)

Country Link
EP (1) EP0926700B1 (ja)
JP (1) JP3853994B2 (ja)
CN (1) CN100361267C (ja)
CZ (1) CZ291751B6 (ja)
DE (1) DE69833844T2 (ja)
HU (1) HU221939B1 (ja)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070024169A1 (en) * 2005-07-29 2007-02-01 Koegler John M Iii Method of forming a lamp assembly
CN101980353B (zh) * 2010-10-14 2013-04-17 杨潮平 共烧封接高效陶瓷灯及其制备方法

Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4665344A (en) * 1984-04-25 1987-05-12 Ngk Insulators, Ltd. Ceramic envelope device for high-pressure discharge lamp
US4731561A (en) * 1984-12-17 1988-03-15 Ngk Insulators, Ltd. Ceramic envelope device for high-pressure discharge lamp
JPS63160147A (ja) * 1986-12-15 1988-07-02 ジー・ティー・イー・プロダクツ・コーポレイション ナトリウム及びメタル−ハライドランプ用の改良されたインリード
CA1311012C (en) * 1988-05-13 1992-12-01 Richard A. Snellgrove Arc tube and high pressure discharge lamp including same
JPH02132750A (ja) * 1988-11-11 1990-05-22 Kyocera Corp 高圧放電灯
EP0609477B1 (en) * 1993-02-05 1999-05-06 Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH Ceramic discharge vessel for high-pressure lamps, method of manufacturing same, and related sealing material
JPH07211292A (ja) * 1994-01-19 1995-08-11 Toto Ltd 金属蒸気発光管の封止部構造
US6066918A (en) * 1995-01-13 2000-05-23 Ngk Insulators, Ltd. High pressure discharge lamp with an improved sealing system and method of producing the same
JPH08273616A (ja) * 1995-03-31 1996-10-18 Toto Ltd 金属蒸気発光管の開口部の封止部構造
JP3151166B2 (ja) * 1996-05-16 2001-04-03 日本碍子株式会社 高圧放電灯およびその製造方法

Also Published As

Publication number Publication date
HU221939B1 (hu) 2003-02-28
JPH11233068A (ja) 1999-08-27
DE69833844D1 (de) 2006-05-11
HU9802973D0 (en) 1999-02-01
HUP9802973A3 (en) 2001-03-28
HUP9802973A2 (hu) 1999-07-28
DE69833844T2 (de) 2006-10-05
CZ291751B6 (cs) 2003-05-14
EP0926700A2 (en) 1999-06-30
EP0926700A3 (en) 1999-12-08
CN1229264A (zh) 1999-09-22
JP3853994B2 (ja) 2006-12-06
CZ429698A3 (cs) 2000-05-17
CN100361267C (zh) 2008-01-09

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