WO2008139186A1 - Electrodeless bulb - Google Patents

Electrodeless bulb Download PDF

Info

Publication number
WO2008139186A1
WO2008139186A1 PCT/GB2008/001653 GB2008001653W WO2008139186A1 WO 2008139186 A1 WO2008139186 A1 WO 2008139186A1 GB 2008001653 W GB2008001653 W GB 2008001653W WO 2008139186 A1 WO2008139186 A1 WO 2008139186A1
Authority
WO
WIPO (PCT)
Prior art keywords
bulb
electrodeless bulb
stem
electrodeless
plug
Prior art date
Application number
PCT/GB2008/001653
Other languages
French (fr)
Inventor
Edwin Charles Odell
Barry Preston
Original Assignee
Ceravision Limited
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 Ceravision Limited filed Critical Ceravision Limited
Publication of WO2008139186A1 publication Critical patent/WO2008139186A1/en

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J65/00—Lamps without any electrode inside the vessel; Lamps with at least one main electrode outside the vessel
    • H01J65/04—Lamps in which a gas filling is excited to luminesce by an external electromagnetic field or by external corpuscular radiation, e.g. for indicating plasma display panels
    • H01J65/042—Lamps in which a gas filling is excited to luminesce by an external electromagnetic field or by external corpuscular radiation, e.g. for indicating plasma display panels by an external electromagnetic field
    • H01J65/044—Lamps in which a gas filling is excited to luminesce by an external electromagnetic field or by external corpuscular radiation, e.g. for indicating plasma display panels by an external electromagnetic field the field being produced by a separate microwave unit
    • 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
    • H01J61/302—Vessels; Containers characterised by the material 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
    • H01J61/36—Seals between parts of vessels; Seals for leading-in conductors; Leading-in conductors
    • H01J61/361—Seals between parts of vessel
    • H01J61/363—End-disc seals or plug seals
    • 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
    • H01J9/40—Closing vessels

Definitions

  • the present invention relates to an electrodeless bulb.
  • the object of the present invention is to provide an improved electrodeless bulb of ceramic material.
  • an electrodeless bulb of ceramic material comprising:
  • the stem and plug can be of different materials - albeit with the same coefficient of thermal expansion - normally they will be of the same materials.
  • the ceramic material can be translucent or transparent.
  • a example of the former is polycrystalline alumina and one of the latter is polycrystalline Yttrium Aluminium Garnet - YAG.
  • Other possible materials are aluminium nitride and single crystal sapphire.
  • the fill will be of a noble gas, typically xenon or krypton and a metal halide such as indium bromide. Nevertheless, other volatile substances that are known to emit light when excited as a plasma can be used.
  • a noble gas typically xenon or krypton
  • a metal halide such as indium bromide
  • the bulb Whilst it is possible to fabricate the bulb from a first tube of green ceramic providing the hollow bulb, a green plug inserted in one end thereof and a green smaller diameter tube inserted in the other, these components being fired together to unify the bulb; in the preferred embodiment, the components are moulded as one of green ceramic and then fired.
  • the moulding can be made around a lost wax core or by slip casting in a porous mould.
  • the plug can be sealed within the stem by local melting of the material of the stem and/or the plug as by a laser; preferably the plug is sealed in place with a separate fusible material having a coefficient of thermal expansion compatible with that of the material of the bulb, including the plug.
  • the fusible material can be:
  • frit glass or a mixture of metal oxides not already fused together and ground down as frit is or an inert metal such as platinum applied in powder or foil form; and can be
  • the bulb will be used in a lamp, in combination with a ceramic waveguide, in which the bulb is mounted, and a microwave radiator positioned within the waveguide and from which microwave energy is transferred via the waveguide to the bulb for its light emitting excitation in use.
  • Figure 1 is a perspective view of a bulb in accordance with the invention
  • Figure 2 is a cross-sectional side view of the bulb
  • Figure 3 is diagrammatic view of the bulb in combination with a ceramic wave guide
  • Figure 4 is a diagrammatic side view of a bulb being sealed
  • Figure 5 is a view similar to Figure 2 of another bulb of the invention.
  • a bulb 1 of polycrystalline alumina has a main bulb tube 2, an end plug 3, a neck 4 and a plug 5.
  • the pieces are all formed, as by moulding, in the green state and then fired.
  • the pieces 1 to 4 are fired after assembly together unifying them into a unitary construction, whilst the plug is fired separately.
  • the bulb is finally assembled in a chamber, not shown, which is evacuated and then filled typically with xenon or krypton.
  • An open-centred, cylinder of graphite 12 is placed around the neck.
  • the plug which has a leg 14 and a head 15 has a ring of halide resistant frit 16 - typically yttrium alumina silica (Y 2 O 3 - Al 2 O 3 - SiO 2 ) - placed on the leg against the head.
  • the leg is then inserted in the neck.
  • the graphite cylinder is encircled by an RF coil 17.
  • the latter can be provided within a quartz bell jar, not shown but provided immediately around the graphite cylinder, with the coil 17 arranged outside the bell jar.
  • the graphite absorbs the energy supplied and heats to red heat, passing radiant heat to the neck.
  • the frit melts and is drawn by capillary action into the neck along the leg 14.
  • the copper block is kept cooling by cooling water flow and cools the bulb.
  • the bulb neck cools and is sealed. This process is capable of sealing many bulbs at once, with many recesses 18 in the copper for many bulbs and many openings 19 in the graphite.
  • the bulb In use, the bulb is placed in a bore 21 in a ceramic wave guide 22, with a microwave feed 23. The sealed neck is received in a bore 24 in a back metal plate 25. On excitation, the metal halide vaporises and emits light. To allow light that is radiated from the main bulb tube, as opposed to from the end plug, to be used, the bore 21 can be slightly tapered 26 as shown or it can be a straight bore. Further as shown, the tip of the bulb can extend beyond the ceramic wave guide for enhanced usefulness of emitted light.
  • Figure 5 is shown an alternative bulb 31, sealed in the same way but having a smooth stress relieving shape produced by slip casting of the bulb in the green state.
  • the above described bulbs have advantage over our existing quartz bulbs in that they are able to operate at a higher temperature. Thus size for size they can be driven at a higher wattage - or be smaller and driven at the same wattage. Operation at a higher temperature results in a higher specific light output, i.e. a higher light output per watt of drive energy.
  • the bulb can be shaped as desired for best optical efficiency, e.g. with a lens shaped end. Also other ceramic materials are expected to be found to be suitable.

Abstract

A bulb (1) of polycrystalline alumina has a main bulb tube (2) providing a bulb envelope, an end plug (3), a neck (4) and a plug (5). The plug is sealed into the neck with a frit (16). Prior to sealing a plasma charge of indium bromide and krypton is placed in the bulb.

Description

ELECTRODELESS BULB
The present invention relates to an electrodeless bulb.
In our International Patent Application No PCT/GB05/005080, dated 23rd
December 2005 and now published under No WO 2006/070190, we have described and claimed a method of making an electrodeless bulb, the method comprising the steps of:
• providing a bulb enclosure of quartz glass, • forming an adjacent neck having a bore less than a transverse internal dimension of the bulb enclosure either:
• integrally with the bulb enclosure or
• in a branch tube opening into the bulb enclosure,
• inserting at least one pellet of excitable material into the bulb enclosure through the adjacent neck,
• evacuating the bulb enclosure through the adjacent neck and
• sealing the bulb.
The object of the present invention is to provide an improved electrodeless bulb of ceramic material.
According to the invention there is provided an electrodeless bulb of ceramic material, the bulb comprising:
• a hollow bulb envelope of ceramic material, • a stern of ceramic material extending from the bulb,
• a plug of ceramic material sealingly received within the stem and
• a charge of excitable material.
Whilst it is envisaged that the stem and plug can be of different materials - albeit with the same coefficient of thermal expansion - normally they will be of the same materials. The ceramic material can be translucent or transparent. A example of the former is polycrystalline alumina and one of the latter is polycrystalline Yttrium Aluminium Garnet - YAG. Other possible materials are aluminium nitride and single crystal sapphire.
Normally the fill will be of a noble gas, typically xenon or krypton and a metal halide such as indium bromide. Nevertheless, other volatile substances that are known to emit light when excited as a plasma can be used.
Whilst it is possible to fabricate the bulb from a first tube of green ceramic providing the hollow bulb, a green plug inserted in one end thereof and a green smaller diameter tube inserted in the other, these components being fired together to unify the bulb; in the preferred embodiment, the components are moulded as one of green ceramic and then fired. The moulding can be made around a lost wax core or by slip casting in a porous mould.
Whilst it is envisaged that the plug can be sealed within the stem by local melting of the material of the stem and/or the plug as by a laser; preferably the plug is sealed in place with a separate fusible material having a coefficient of thermal expansion compatible with that of the material of the bulb, including the plug. The fusible material can be:
• a frit glass or a mixture of metal oxides not already fused together and ground down as frit is or an inert metal such as platinum applied in powder or foil form; and can be
• inherently or compounded to be resistant to attack by halides, where the excitable material is or includes a halide, or by other excitable material used to charge the bulb; and can be
• fused by means of a laser or an inductively or resistively heated furnace.
Normally the bulb will be used in a lamp, in combination with a ceramic waveguide, in which the bulb is mounted, and a microwave radiator positioned within the waveguide and from which microwave energy is transferred via the waveguide to the bulb for its light emitting excitation in use.
To help understanding of the invention, a specific embodiment thereof will now be described by way of example and with reference to the accompanying drawings, in which:
Figure 1 is a perspective view of a bulb in accordance with the invention; Figure 2 is a cross-sectional side view of the bulb; Figure 3 is diagrammatic view of the bulb in combination with a ceramic wave guide;
Figure 4 is a diagrammatic side view of a bulb being sealed;
Figure 5 is a view similar to Figure 2 of another bulb of the invention.
Referring to the drawings a bulb 1 of polycrystalline alumina has a main bulb tube 2, an end plug 3, a neck 4 and a plug 5. The pieces are all formed, as by moulding, in the green state and then fired. The pieces 1 to 4 are fired after assembly together unifying them into a unitary construction, whilst the plug is fired separately.
With reference to Figure 4, the bulb is finally assembled in a chamber, not shown, which is evacuated and then filled typically with xenon or krypton. A pellet 6 of metal halide, typically indium bromide, possibly with traces of other halides to adjust the spectral distribution of emitted light, is deposited in the bulb. This is supported in a cooled copper block 11, with the neck protruding. An open-centred, cylinder of graphite 12 is placed around the neck. The plug, which has a leg 14 and a head 15 has a ring of halide resistant frit 16 - typically yttrium alumina silica (Y2O3 - Al2O3 - SiO2) - placed on the leg against the head. The leg is then inserted in the neck. The graphite cylinder is encircled by an RF coil 17. For compactness of the evacuated chamber, the latter can be provided within a quartz bell jar, not shown but provided immediately around the graphite cylinder, with the coil 17 arranged outside the bell jar. On excitement of the coil, the graphite absorbs the energy supplied and heats to red heat, passing radiant heat to the neck. The frit melts and is drawn by capillary action into the neck along the leg 14. To stop the metal halide evaporating prematurely the copper block is kept cooling by cooling water flow and cools the bulb. On switching off of the RF feed to the coil the bulb neck cools and is sealed. This process is capable of sealing many bulbs at once, with many recesses 18 in the copper for many bulbs and many openings 19 in the graphite.
In use, the bulb is placed in a bore 21 in a ceramic wave guide 22, with a microwave feed 23. The sealed neck is received in a bore 24 in a back metal plate 25. On excitation, the metal halide vaporises and emits light. To allow light that is radiated from the main bulb tube, as opposed to from the end plug, to be used, the bore 21 can be slightly tapered 26 as shown or it can be a straight bore. Further as shown, the tip of the bulb can extend beyond the ceramic wave guide for enhanced usefulness of emitted light.
In Figure 5 is shown an alternative bulb 31, sealed in the same way but having a smooth stress relieving shape produced by slip casting of the bulb in the green state.
The above described bulbs have advantage over our existing quartz bulbs in that they are able to operate at a higher temperature. Thus size for size they can be driven at a higher wattage - or be smaller and driven at the same wattage. Operation at a higher temperature results in a higher specific light output, i.e. a higher light output per watt of drive energy.
The invention is not intended to be restricted to the details of the above described embodiment. For instance, as shown in Figure 5, the bulb can be shaped as desired for best optical efficiency, e.g. with a lens shaped end. Also other ceramic materials are expected to be found to be suitable.

Claims

CLAIMS:
1. An electrodeless bulb of ceramic material, the bulb comprising:
• a hollow bulb envelope of ceramic material,
• a stem of ceramic material extending from the bulb, • a plug of ceramic material sealingly received within the stem and
• a charge of excitable material.
2. An electrodeless bulb as claimed in claim 1, wherein the bulb envelope and the stem are of unitary construction from a single fired moulding or casting, including a closed end opposite the stem.
3. An electrodeless bulb as claimed in claim 1, wherein the stem is an insertion sealed by firing into an end of the bulb envelope and a plug is an insertion sealed by firing into the other end thereof.
4. An electrodeless bulb as claimed in claim 1, claim 2 or claim 3, wherein the plug within the stem has a head determining its position in the stem during sealing.
5. An electrodeless bulb as claimed in any preceding claim, wherein the plug is sealed into the stem by fusing of the material of the stem and/or the plug.
6. An electrodeless bulb as claimed in any one of claims 1 to 4, wherein the plug is sealed into the stem with a separate fusible material.
7. An electrodeless bulb as claimed in claim 6, wherein the fusible material has a coefficient of expansion compatible with that of the ceramic material.
8. An electrodeless bulb as claimed in claim 6 or claim 7, where resistant to chemical reaction at elevated temperature with the charge of excitable material.
9. An electrodeless bulb as claimed in claim 6, claim 7 or claim 8, wherein the fusible material is a glass frit material.
10. An electrodeless bulb as claimed in claim 6, claim 7 or claim 8, wherein the fusible material is a mixture of previously un-fused metal oxides.
11. An electrodeless bulb as claimed in claim 6, claim 7 or claim 8, wherein the fusible material is metallic.
12. An electrodeless bulb as claimed in any preceding claim, wherein the envelope at least is of translucent ceramic material.
13. An electrodeless bulb as claimed in claim 12, wherein the translucent ceramic material is polycrystalline alumina.
14. An electrodeless bulb as claimed in any one of claims 1 to 11, wherein the envelope at least is of transparent ceramic material.
15. An electrodeless bulb as claimed in claim 14, wherein the transparent ceramic material is polycrystalline Yttrium Aluminium Garnet.
16. An electrodeless bulb as claimed in any preceding claim, wherein the charge is of metal halide and noble gas.
17. An electrodeless bulb as claimed in claim 16, wherein the metal halide is indium bromide and the noble gas is xenon.
18. An electrodeless bulb as claimed in any preceding claim, in combination as a lamp with a ceramic waveguide, in which the bulb is mounted, and a microwave radiator positioned within the waveguide and from which microwave energy is transferred via the waveguide to the bulb for its light emitting excitation in use.
PCT/GB2008/001653 2007-05-15 2008-05-13 Electrodeless bulb WO2008139186A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB0709343A GB0709343D0 (en) 2007-05-15 2007-05-15 Electrodeless bulb
GB0709343.8 2007-05-15

Publications (1)

Publication Number Publication Date
WO2008139186A1 true WO2008139186A1 (en) 2008-11-20

Family

ID=38234495

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB2008/001653 WO2008139186A1 (en) 2007-05-15 2008-05-13 Electrodeless bulb

Country Status (3)

Country Link
GB (1) GB0709343D0 (en)
TW (1) TW201015615A (en)
WO (1) WO2008139186A1 (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010094938A1 (en) * 2009-02-23 2010-08-26 Ceravision Limited Plasma crucible sealing
WO2014045044A1 (en) * 2012-09-19 2014-03-27 Ceravision Limited Crucible for a luwpl
US9552976B2 (en) 2013-05-10 2017-01-24 General Electric Company Optimized HID arc tube geometry

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111554562A (en) 2015-12-11 2020-08-18 李昆达 Electrodeless lamp
TWI596648B (en) * 2015-12-11 2017-08-21 李昆達 Electrodeless lamp

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3747173A (en) * 1969-10-15 1973-07-24 Tektronix Inc Method of sealing ceramic to nonmetalic using indium alloy seal
EP0671758A2 (en) * 1994-03-11 1995-09-13 Toshiba Lighting & Technology Corporation Electrodeless high intensity discharge lamp
EP0786798A1 (en) * 1996-01-24 1997-07-30 Matsushita Electric Industrial Co., Ltd. Electrodeless discharge lamp and the manufacturing method thereof
EP0786797A2 (en) * 1996-01-29 1997-07-30 General Electric Company Arctube for high pressure discharge lamp
US5727975A (en) * 1995-08-01 1998-03-17 Osram Sylvania Inc. Arc tube for electrodeless lamp
JP2001250512A (en) * 2000-03-07 2001-09-14 Japan Storage Battery Co Ltd Microwave driven electrodeless ceramic lamp
US20010035720A1 (en) * 2000-03-27 2001-11-01 Charles Guthrie High intensity light source
EP1616657A1 (en) * 2004-07-15 2006-01-18 Delphi Technologies, Inc. Braze alloy containing particulate material

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3747173A (en) * 1969-10-15 1973-07-24 Tektronix Inc Method of sealing ceramic to nonmetalic using indium alloy seal
EP0671758A2 (en) * 1994-03-11 1995-09-13 Toshiba Lighting & Technology Corporation Electrodeless high intensity discharge lamp
US5727975A (en) * 1995-08-01 1998-03-17 Osram Sylvania Inc. Arc tube for electrodeless lamp
EP0786798A1 (en) * 1996-01-24 1997-07-30 Matsushita Electric Industrial Co., Ltd. Electrodeless discharge lamp and the manufacturing method thereof
EP0786797A2 (en) * 1996-01-29 1997-07-30 General Electric Company Arctube for high pressure discharge lamp
JP2001250512A (en) * 2000-03-07 2001-09-14 Japan Storage Battery Co Ltd Microwave driven electrodeless ceramic lamp
US20010035720A1 (en) * 2000-03-27 2001-11-01 Charles Guthrie High intensity light source
EP1616657A1 (en) * 2004-07-15 2006-01-18 Delphi Technologies, Inc. Braze alloy containing particulate material

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010094938A1 (en) * 2009-02-23 2010-08-26 Ceravision Limited Plasma crucible sealing
US8469763B2 (en) 2009-02-23 2013-06-25 Ceravision Limited Plasma crucible sealing
TWI478206B (en) * 2009-02-23 2015-03-21 Ceravision Ltd Plasma crucible sealing and method of sealingsame
RU2551662C2 (en) * 2009-02-23 2015-05-27 Серавижн Лимитед Sealing of plasma crucible
WO2014045044A1 (en) * 2012-09-19 2014-03-27 Ceravision Limited Crucible for a luwpl
US20150221494A1 (en) * 2012-09-19 2015-08-06 Ceravision Limited Crucible for a LUWPL
JP2015529387A (en) * 2012-09-19 2015-10-05 セラビジョン リミテッド LUWPL crucible
AU2013320002B2 (en) * 2012-09-19 2017-11-23 Ceravision Limited Crucible for a LUWPL
US9552976B2 (en) 2013-05-10 2017-01-24 General Electric Company Optimized HID arc tube geometry

Also Published As

Publication number Publication date
GB0709343D0 (en) 2007-06-27
TW201015615A (en) 2010-04-16

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