WO2002049074A1 - High pressure discharge lamp - Google Patents

High pressure discharge lamp Download PDF

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Publication number
WO2002049074A1
WO2002049074A1 PCT/IB2001/002521 IB0102521W WO0249074A1 WO 2002049074 A1 WO2002049074 A1 WO 2002049074A1 IB 0102521 W IB0102521 W IB 0102521W WO 0249074 A1 WO0249074 A1 WO 0249074A1
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WO
WIPO (PCT)
Prior art keywords
channel
lead
cross
discharge lamp
internal perimeter
Prior art date
Application number
PCT/IB2001/002521
Other languages
French (fr)
Inventor
Theodorus G. M. M. Kappen
Lucas J. A. M. Beckers
Original Assignee
Koninklijke Philips Electronics N.V.
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 N.V. filed Critical Koninklijke Philips Electronics N.V.
Priority to AU2002222367A priority Critical patent/AU2002222367A1/en
Publication of WO2002049074A1 publication Critical patent/WO2002049074A1/en

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Classifications

    • 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
    • H01J9/24—Manufacture or joining of vessels, leading-in conductors or bases
    • H01J9/245—Manufacture or joining of vessels, leading-in conductors or bases specially adapted for gas discharge tubes or lamps
    • H01J9/247—Manufacture or joining of vessels, leading-in conductors or bases specially adapted for gas discharge tubes or lamps specially adapted for gas-discharge lamps
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J5/00—Details relating to vessels or to leading-in conductors common to two or more basic types of discharge tubes or lamps
    • H01J5/50—Means forming part of the tube or lamps for the purpose of providing electrical connection to it
    • H01J5/52—Means forming part of the tube or lamps for the purpose of providing electrical connection to it directly applied to or forming part of the vessel
    • 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
    • H01J61/82—Lamps with high-pressure unconstricted discharge having a cold pressure > 400 Torr
    • H01J61/827—Metal halide arc lamps

Definitions

  • the present invention relates to a high pressure discharge lamp provided with a monolithic discharge vessel having a ceramic wall which encloses a discharge space in which an electrode is positioned and which is provided with an elongated lead-through channel with a channel wall with an internal perimeter in cross-section, in which a lead- through element is closely fitted which connects the electrode to an external conductor and which has a gas-tight connection to the channel wall close to an end of the lead-through channel.
  • Such a lamp is described in EP0926106.
  • the known lamp is a metal halide lamp.
  • An elongated lead-through channel is relevant to create the required temperature gradient across the discharge vessel during operation of the lamp.
  • the maximum permissible wall temperature of the discharge vessel should not be exceeded, while on the other hand it must be assured that both the temperature immediately behind the electrode is sufficiently high and simultaneously the temperature at the gas-tight seal is at least 50 K but preferably considerably more than 50 K lower.
  • the tight fit of the channel wall around the lead-through element is also important to limit the required fill volume of the discharge vessel to acceptable proportions.
  • 'ceramic wall' refers to a wall of gas-tight metal oxide, either monocrystalline such as sapphire, or densely sintered polycrystalline such as alumina, YAG or densely sintered gas-tight polycrystalline metal nitride such as A1N.
  • the ceramic material is translucent at least the area of the discharge space.
  • a monolithic discharge vessel is one-piece discharge vessel which therefore does not have any sintering seams. Suitable production methods include, for example, injection moulding, slip casting and gel casting. In known lamps an end of a lead-through channel often serves as a reference plane for the accurate positioning of the inner electrode.
  • the present invention aims to remedy this disadvantage. This is accomplished in that a lamp of the type referred to in the introduction is characterized, as a lamp in accordance with the invention, by the fact that the internal perimeter in cross-section of the lead-through channel locally acts as a stop for positioning the lead-through element.
  • a most suitable profile of the relevant internal perimeter of the lead-through channel of a lamp according to the present invention has been found to be a lead-through channel with a step-like constriction at the location of the stop. This makes the accurate positioning of the lead-through element relative to the monolithic discharge vessel possible.
  • the lead-through channel has a first part which connects to the discharge space with an internal perimeter in cross-section which encloses an area SI, and a second part which connects to the first part with an internal perimeter in cross-section which encloses an area S2 such that SI ⁇ S2.
  • the monolithic discharge vessel is produced by a slip casting method.
  • the slip casting method comprises injecting slip into a porous outer mould using a hollow needle extending into the outer mould and thereby forming an inner mould for the channel wall of the lead- through channel.
  • a suitable gas-tight connection between the lead-through element and the channel wall is formed by a sealing glass or sealing ceramic.
  • Another option is gas-tight sintering of the relevant lead-through element to the channel wall at the location of the gas- tight connection.
  • the lead-through element, at least at the location of the gas-tight connection shall preferably be a cermet, for example comprising Al 2 O 3 (70 vol%) and Mo (30 vol%).
  • Figure 1 schematically shows a lamp according to the invention
  • Figure 2 shows the discharge vessel of the lamp according to Figure 1 in detail
  • Figure 3 shows a cross-section of a part of the discharge vessel according to Figure 2.
  • Figure 1 shows a high-pressure discharge lamp with a monolithic discharge vessel 1 with a ceramic wall, for example aluminium oxide, which surrounds a discharge space 11 in which an electrode 5, 6 is positioned.
  • a lead-through element 56, 66 connects the electrode 5, 6 to an external conductor 7, 8.
  • the discharge vessel is surrounded by an envelope 101 at an end of which a lamp base 2 is provided.
  • a lamp base 2 is provided.
  • the lamp there is a discharge between electrodes 5, 6.
  • External conductor 7 is connected by current conductor 90 to a first electrical contact which forms part of the lamp base 2.
  • External conductor 8 is connected by current conductor 100 to a second electrical contact which forms part of the lamp base 2.
  • the lamp is a metal halide lamp whose discharge vessel 1 contains a filling which can be ionized, containing, in addition to Hg and an inert gas, one or more metal halogenides.
  • FIG 2 the discharge vessel 1 of the lamp in accordance with Figure 1 is shown in greater detail (not to scale).
  • the discharge vessel has a ceramic wall 12 and is provided with an elongated lead-through channel 50, 60 with a channel wall with an internal perimeter in cross-section.
  • Two electrodes 5, 6 are positioned in the discharge space which are connected to the external conductors 7, 8 by the lead-through elements 56, 66.
  • the lead- through elements 56, 66 are accommodated in the relevant lead-through channel 50, 60 and are closely surrounded by the channel wall 121, 122 of the relevant lead-through channel 50, 60 and, at the end and close to the end of the lead-through channel, said lead-through elements are connected in a gastight manner to the relevant channel wall by a sealing glass or sealing ceramic 15.
  • the internal perimeter in cross-section of the lead-through channel locally forms a stop 500, 600 taking the form of a step-shaped constriction to position the lead- through element 56, 66.
  • a Mo bar is particularly suitable as a lead-through element in view of the relatively high resistance against halogenide, while Nb is preferred as an external conductor in view of its relatively high ductility and attractive coefficient of expansion.
  • Figure 3 shows a cross-section of lead-through channel 50 as indicated in Figure 2 by III- III.
  • the lead-through channel 50 has a first part 51 which connects to the discharge space with an internal perimeter in cross-section Ol which encloses an area SI and a second part 52 which connects to the first part with an internal perimeter in cross-section O2 which encloses an area S2 such that SI ⁇ S2.
  • the perimeters in cross-section of the first and the second part of the lead-through channel are circular.
  • This geometry is preferable for the series production of lamps at an industrial scale.
  • other geometries, symmetric and asymmetric are equally possible. This applies equally to the constriction of the perimeter of the first part of the lead-through channel.
  • the stop can be formed by three lugs or flange elements that protrude transversely into the channel and, preferably, are rotationally symmetrically distributed along the internal perimeter.
  • a slip casting method shall be used comprising the following steps: • filling a porous outer mould with slip through a first hollow needle provided with a channel which extends partly into the outer mould, • the deposition of the slip particles against the filled outer mould,
  • Each of the needles in so far as it extends into the outer mould, forms an inner mould of a channel wall of one of the lead-through channels to be formed in the discharge vessel to be formed.
  • the body formed in this way after the removal of the hollow needles, is then sintered to a translucent gas-tight body in the usual way in a sintering kiln, after which it is used in the usual way to produce a discharge vessel to manufacture a lamp.
  • a sintering kiln After which it is used in the usual way to produce a discharge vessel to manufacture a lamp.
  • a suitable slip has the composition shown below: Alumina powder 40 vol%
  • the deposition of the injected slip particles shall occur under the influence of capillary absorption of the slip liquid into the pores of the outer mould.
  • CaSO 4 plaster
  • Another suitable option is for example to use an outer mould material of the same type as that used for the ceramic wall to be formed, such as for example Al 2 O .
  • a sintering dopant is generally added to the slip material, for example MgO.
  • a suitable material for the surface of the outer mould is a material related to the sintering dopant.
  • MgCO 3 is most suitable. The attractive property of MgCO 3 is that in water it has a solubility product which is almost identical to that of CaSO 4 .

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Vessels And Coating Films For Discharge Lamps (AREA)

Abstract

The invention relates to a high pressure discharge lamp provided with a monolithic discharge vessel having a ceramic wall, which encloses a discharge space in which an electrode is disposed. The discharge vessel is provided with a leadthrough channel having an internal perimeter in cross section, in which channel a leadthrough element is accommodated that connects the electrode to an external conductor. According to the invention, the internal perimeter in cross section of the leadthrough channel is locally provided with a stop for positioning of the leadthrough element.

Description

High pressure discharge lamp
The present invention relates to a high pressure discharge lamp provided with a monolithic discharge vessel having a ceramic wall which encloses a discharge space in which an electrode is positioned and which is provided with an elongated lead-through channel with a channel wall with an internal perimeter in cross-section, in which a lead- through element is closely fitted which connects the electrode to an external conductor and which has a gas-tight connection to the channel wall close to an end of the lead-through channel.
Such a lamp is described in EP0926106. The known lamp is a metal halide lamp. Such a discharge vessel construction is particularly suited to miniaturization and the creation of lamps with a low rated power and a high efficiency. An elongated lead-through channel is relevant to create the required temperature gradient across the discharge vessel during operation of the lamp. In addition, on the one hand the maximum permissible wall temperature of the discharge vessel should not be exceeded, while on the other hand it must be assured that both the temperature immediately behind the electrode is sufficiently high and simultaneously the temperature at the gas-tight seal is at least 50 K but preferably considerably more than 50 K lower. The tight fit of the channel wall around the lead-through element is also important to limit the required fill volume of the discharge vessel to acceptable proportions.
In this description and the claims, 'ceramic wall' refers to a wall of gas-tight metal oxide, either monocrystalline such as sapphire, or densely sintered polycrystalline such as alumina, YAG or densely sintered gas-tight polycrystalline metal nitride such as A1N. The ceramic material is translucent at least the area of the discharge space. A monolithic discharge vessel is one-piece discharge vessel which therefore does not have any sintering seams. Suitable production methods include, for example, injection moulding, slip casting and gel casting. In known lamps an end of a lead-through channel often serves as a reference plane for the accurate positioning of the inner electrode. In contrast to manufacturing methods in which two or more parts of the discharge vessel are sintered together to form a gas-tight seal, methods for the production of a monolithic discharge vessel result in less accurate external dimensions, specifically at the end of the lead-through channel. This is disadvantageous with respect to realizing the required positioning accuracy of the electrode in the discharge space.
The present invention aims to remedy this disadvantage. This is accomplished in that a lamp of the type referred to in the introduction is characterized, as a lamp in accordance with the invention, by the fact that the internal perimeter in cross-section of the lead-through channel locally acts as a stop for positioning the lead-through element.
The insight that the internal perimeter in cross-section of the lead-through channel is most suitable for forming a stop for a lead-through element leads to the idea of suitably profiling the relevant internal perimeter of the lead-through channel. In the case of a monolithic discharge vessel this is easily, reliably and reproducibly achieved, preferably, by using a suitably shaped mould during the production of the discharge vessel, thus obviating the need for further processing, such as boring the lead-through channel after producing the ceramic vessel, to ensure accurate electrode positioning. In the case a monolithic ceramic body is used, such further processing often leads to the objection referred to above, i.e. that the external dimensionals of the end of the lead-through channel are inaccurate and consequently there is no reliable reference plane to determine where or over what length such further processing should be carried out.
A most suitable profile of the relevant internal perimeter of the lead-through channel of a lamp according to the present invention has been found to be a lead-through channel with a step-like constriction at the location of the stop. This makes the accurate positioning of the lead-through element relative to the monolithic discharge vessel possible. In a further preferred embodiment, the lead-through channel has a first part which connects to the discharge space with an internal perimeter in cross-section which encloses an area SI, and a second part which connects to the first part with an internal perimeter in cross-section which encloses an area S2 such that SI < S2. In a most suitable embodiment of the lamp according to the invention, the monolithic discharge vessel is produced by a slip casting method. The advantage of this is that after forming the monolithic product it is not necessary to remove an inner mould from the discharge space. In a further improvement of the suitable embodiment, the slip casting method comprises injecting slip into a porous outer mould using a hollow needle extending into the outer mould and thereby forming an inner mould for the channel wall of the lead- through channel. The use of a hollow needle as inner mould in the lead-through channel to be formed has the advantage that there is a great freedom of shape when forming the lead- through channel, which is also substantially independent of the dimensions of the part of the discharge vessel which will envelop the discharge space.
A suitable gas-tight connection between the lead-through element and the channel wall is formed by a sealing glass or sealing ceramic. Another option is gas-tight sintering of the relevant lead-through element to the channel wall at the location of the gas- tight connection. In that case, the lead-through element, at least at the location of the gas-tight connection, shall preferably be a cermet, for example comprising Al2O3 (70 vol%) and Mo (30 vol%).
These and other aspects of the invention are apparent from and will be elucidated, by way of non-limiting example, with reference to the embodiment(s) described hereinafter.
In the drawings (not to scale):
Figure 1 schematically shows a lamp according to the invention, Figure 2 shows the discharge vessel of the lamp according to Figure 1 in detail, and
Figure 3 shows a cross-section of a part of the discharge vessel according to Figure 2.
Figure 1 shows a high-pressure discharge lamp with a monolithic discharge vessel 1 with a ceramic wall, for example aluminium oxide, which surrounds a discharge space 11 in which an electrode 5, 6 is positioned. A lead-through element 56, 66, connects the electrode 5, 6 to an external conductor 7, 8.
The discharge vessel is surrounded by an envelope 101 at an end of which a lamp base 2 is provided. During the operation of the lamp there is a discharge between electrodes 5, 6. External conductor 7 is connected by current conductor 90 to a first electrical contact which forms part of the lamp base 2. External conductor 8 is connected by current conductor 100 to a second electrical contact which forms part of the lamp base 2. In the case described here, the lamp is a metal halide lamp whose discharge vessel 1 contains a filling which can be ionized, containing, in addition to Hg and an inert gas, one or more metal halogenides.
In Figure 2 the discharge vessel 1 of the lamp in accordance with Figure 1 is shown in greater detail (not to scale). The discharge vessel has a ceramic wall 12 and is provided with an elongated lead-through channel 50, 60 with a channel wall with an internal perimeter in cross-section. Two electrodes 5, 6 are positioned in the discharge space which are connected to the external conductors 7, 8 by the lead-through elements 56, 66. The lead- through elements 56, 66 are accommodated in the relevant lead-through channel 50, 60 and are closely surrounded by the channel wall 121, 122 of the relevant lead-through channel 50, 60 and, at the end and close to the end of the lead-through channel, said lead-through elements are connected in a gastight manner to the relevant channel wall by a sealing glass or sealing ceramic 15.
The internal perimeter in cross-section of the lead-through channel locally forms a stop 500, 600 taking the form of a step-shaped constriction to position the lead- through element 56, 66.
A Mo bar is particularly suitable as a lead-through element in view of the relatively high resistance against halogenide, while Nb is preferred as an external conductor in view of its relatively high ductility and attractive coefficient of expansion.
Figure 3 shows a cross-section of lead-through channel 50 as indicated in Figure 2 by III- III. The lead-through channel 50 has a first part 51 which connects to the discharge space with an internal perimeter in cross-section Ol which encloses an area SI and a second part 52 which connects to the first part with an internal perimeter in cross-section O2 which encloses an area S2 such that SI < S2. In the case illustrated here, the perimeters in cross-section of the first and the second part of the lead-through channel are circular. This geometry is preferable for the series production of lamps at an industrial scale. However, other geometries, symmetric and asymmetric are equally possible. This applies equally to the constriction of the perimeter of the first part of the lead-through channel. For example, the stop can be formed by three lugs or flange elements that protrude transversely into the channel and, preferably, are rotationally symmetrically distributed along the internal perimeter.
Preferably, to produce a discharge vessel in accordance with the described embodiment a slip casting method shall be used comprising the following steps: • filling a porous outer mould with slip through a first hollow needle provided with a channel which extends partly into the outer mould, • the deposition of the slip particles against the filled outer mould,
• removal of surplus slip through a second identically shaped hollow needle which extends partly into the outer mould and which is provided with a channel,
• removal of the outer mould and initial firing of the body formed in this way. Each of the needles, in so far as it extends into the outer mould, forms an inner mould of a channel wall of one of the lead-through channels to be formed in the discharge vessel to be formed.
The body formed in this way, after the removal of the hollow needles, is then sintered to a translucent gas-tight body in the usual way in a sintering kiln, after which it is used in the usual way to produce a discharge vessel to manufacture a lamp. During sintering a certain amount of shrinkage will occur which is known to those skilled in the art.
A suitable slip has the composition shown below: Alumina powder 40 vol%
Citric acid 0.6 vol% Acrylcopolymer 4 vol%
Water 55.4 vol%
Preferably, the deposition of the injected slip particles shall occur under the influence of capillary absorption of the slip liquid into the pores of the outer mould. CaSO4 (plaster) forms a most suitable mould material, which exhibits most favourable demoulding properties. Another suitable option is for example to use an outer mould material of the same type as that used for the ceramic wall to be formed, such as for example Al2O . For the benefit of controlled crystal growth during sintering of the body formed by slip casting, a sintering dopant is generally added to the slip material, for example MgO. A suitable material for the surface of the outer mould is a material related to the sintering dopant. In the event that the slip contains MgO, for example MgCO3 is most suitable. The attractive property of MgCO3 is that in water it has a solubility product which is almost identical to that of CaSO4.
The scope of the present invention is not limited to the embodiments described here. The present invention relates to each new characteristic and each combination of characteristics. Reference numbers in the claims do not limit the scope of protection thereof. The use of the verb "to comprise" and its conjugations does not exclude the presence of elements other than those listed in the claims. The use of the article "a" or "an" in front of an element does not exclude the presence of a multiplicity of such elements.

Claims

CLAIMS:
1. A high-pressure discharge lamp with a monolithic discharge vessel with a ceramic wall which encloses a discharge space within which an electrode is positioned and which is provided with an elongated lead-through channel with a channel wall with an internal perimeter in cross-section, in which a lead-through element is closely fitted which connects the electrode to an external conductor and which has a gas-tight connection to the channel wall close to an end of the lead-through channel, characterized in that the internal perimeter in cross-section of the lead-through channel locally serves as a stop to position the lead-through element.
2. A high-pressure discharge lamp as claimed in claim 1, characterized in that the lead-through channel has a step-shaped constriction at the location of the stop.
3. A high-pressure discharge lamp as claimed in claim 2, characterized in that the lead-through channel has a first part that connects to the discharge space with an internal perimeter in cross-section enclosing an area SI and a second part that connects to the first part with an internal perimeter in cross-section enclosing an area S2, such that SI < S2.
4. A high-pressure discharge lamp as claimed in claim 1, characterized in that the monolithic discharge vessel is obtained by a slip casting process.
5. A high-pressure discharge lamp as claimed in claim 4, characterized in that the slip casting process comprises the filling of a porous outer mould with slip and that the filling of the outer mould is accomplished using a hollow needle extending into the outer mould and thereby forming an inner mould for the channel wall of the lead-through channel.
PCT/IB2001/002521 2000-12-14 2001-12-12 High pressure discharge lamp WO2002049074A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU2002222367A AU2002222367A1 (en) 2000-12-14 2001-12-12 High pressure discharge lamp

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP00204512 2000-12-14
EP00204512.8 2000-12-14

Publications (1)

Publication Number Publication Date
WO2002049074A1 true WO2002049074A1 (en) 2002-06-20

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WO (1) WO2002049074A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008119697A1 (en) * 2007-03-30 2008-10-09 Osram Gesellschaft mit beschränkter Haftung High-pressure discharge lamp

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4799601A (en) * 1982-04-26 1989-01-24 Toshiba Ceramics Co., Ltd. Translucent alumina ceramic tube and a process for making same
EP0333455A2 (en) * 1988-03-16 1989-09-20 Ngk Insulators, Ltd. Ceramic envelope device for high-pressure discharge lamp, and method for producing the same
US5047182A (en) * 1987-11-25 1991-09-10 Ceramics Process Systems Corporation Complex ceramic and metallic shaped by low pressure forming and sublimative drying
US5424608A (en) * 1992-05-18 1995-06-13 Patent-Treuhand-Gesellschaft F. Elektrische Gluehlampen Mbh High-pressure discharge lamp with ceramic discharge vessel
JPH09330682A (en) * 1996-06-10 1997-12-22 Toshiba Lighting & Technol Corp Ceramic discharge lamp, lamp device, lighting device, and liquid crystal projector
JPH11149902A (en) * 1997-11-14 1999-06-02 Matsushita Electric Works Ltd Metallic vapor discharge lamp
EP0926106A1 (en) * 1997-12-16 1999-06-30 Konoshima Chemical Co., Ltd. A corrosion resistant ceramic and a production method thereof
EP0954007A1 (en) * 1997-01-18 1999-11-03 Toto Ltd. Discharge lamp, discharge lamp sealing method, discharge lamp sealing device

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4799601A (en) * 1982-04-26 1989-01-24 Toshiba Ceramics Co., Ltd. Translucent alumina ceramic tube and a process for making same
US5047182A (en) * 1987-11-25 1991-09-10 Ceramics Process Systems Corporation Complex ceramic and metallic shaped by low pressure forming and sublimative drying
EP0333455A2 (en) * 1988-03-16 1989-09-20 Ngk Insulators, Ltd. Ceramic envelope device for high-pressure discharge lamp, and method for producing the same
US5424608A (en) * 1992-05-18 1995-06-13 Patent-Treuhand-Gesellschaft F. Elektrische Gluehlampen Mbh High-pressure discharge lamp with ceramic discharge vessel
JPH09330682A (en) * 1996-06-10 1997-12-22 Toshiba Lighting & Technol Corp Ceramic discharge lamp, lamp device, lighting device, and liquid crystal projector
EP0954007A1 (en) * 1997-01-18 1999-11-03 Toto Ltd. Discharge lamp, discharge lamp sealing method, discharge lamp sealing device
JPH11149902A (en) * 1997-11-14 1999-06-02 Matsushita Electric Works Ltd Metallic vapor discharge lamp
EP0926106A1 (en) * 1997-12-16 1999-06-30 Konoshima Chemical Co., Ltd. A corrosion resistant ceramic and a production method thereof

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Title
PATENT ABSTRACTS OF JAPAN vol. 1998, no. 04 31 March 1998 (1998-03-31) *
PATENT ABSTRACTS OF JAPAN vol. 1999, no. 11 30 September 1999 (1999-09-30) *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008119697A1 (en) * 2007-03-30 2008-10-09 Osram Gesellschaft mit beschränkter Haftung High-pressure discharge lamp

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