CA1205843A - Compact fluorescent lamp with copper-arc excitation - Google Patents
Compact fluorescent lamp with copper-arc excitationInfo
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- CA1205843A CA1205843A CA000407024A CA407024A CA1205843A CA 1205843 A CA1205843 A CA 1205843A CA 000407024 A CA000407024 A CA 000407024A CA 407024 A CA407024 A CA 407024A CA 1205843 A CA1205843 A CA 1205843A
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- lamp
- arc tube
- arc
- copper
- disposed
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
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- Vessels And Coating Films For Discharge Lamps (AREA)
- Discharge Lamp (AREA)
Abstract
COMPACT FLUORESCENT LAMP WITH
COPPER-ARC EXCITATION
Abstract of the Disclosure A fluorescent lamp comprises a small arc tube in which copper, produced by vaporization of a copper halide, radiates in the near ultraviolet region to excite phosphors on an outer jacket. High efficiency results from the conver-sion of copper resonance radiation at 324.7 and 327.4 nano-meters to visible light by the phosphor material. The use of copper halides in small arc tubes makes possible a compact efficient lamp capable of operating in horizontal and vertical positions.
, ..
COPPER-ARC EXCITATION
Abstract of the Disclosure A fluorescent lamp comprises a small arc tube in which copper, produced by vaporization of a copper halide, radiates in the near ultraviolet region to excite phosphors on an outer jacket. High efficiency results from the conver-sion of copper resonance radiation at 324.7 and 327.4 nano-meters to visible light by the phosphor material. The use of copper halides in small arc tubes makes possible a compact efficient lamp capable of operating in horizontal and vertical positions.
, ..
Description
COMPACT FLUORESCENT LAMP WITH
C~.PP.~-ARC EXCI~ATION
Back~round of the ImTention This invention rela~es ~o fluorescent lamps and more parti::ularly to fluorescen~ lamps corltainiTIg an interior arc discharge tube. Moreove~, the present in~ention also 0~ relates to a combination fluorescent and arc discharge lamp in which the l~ght ou~put may be var;ed as between light from ~che arc an~ light from the p~osp~o~.
At present) much of present-day lighting needs axe supplied throu~ the use of iFIefficient incandeseent la~ap~.
While these lamps are relatively in~cpensive and are produced~ in large quantities with knowrl technolo8;y, nonet:hele~s the increasing cost of electric energy has, in rece~ years, chaDged the econo~nic situation. In particular, i the cost of operating ~ncandescent lamps is considered, along with their relat~vely short lifetimes, the incandescen~
~ may be uneconomical in certain situations parti ularly those in which they are compared agalnst long life, high effi-ciency lamps. A number of different kinds of lamp geometries and designs have at~empted to ulill this need, Conventional fluoresee~t lamps, in wh~eh the vi~ible radiation is prod~ced by a phosphor coating on the nterior of a partially evacuated disrharge tube, are eficient and long lived but lack the geometry necessary or use in standard luminaires and fixture~s, ~' ""~, :llZ()5~3 Another potential incandescent lamp replacement is the solenoidal elec~cric field lamp (Sl:F ~ amp) which is similar in operation to a fluorescent lamp but in which an electronic ballast drives a ferrite core disposed wi~hin 05 an arc discharge medium to produce ultraviolet radia~ion which impi~ges upon a phosphor coate~ upon the 1æmp tu~P
w~ll S9 as to produce the des~red radiation. Ihese lamps are smallt c~mpact and, with an appropriate electronic ball~st, easily replace the con~entisnal incandescent lamp in most fixture~/ It is not, h~wever, an arc lam~ in which the prlmary llght source ls from the arc discharge, Rather, it is a fluorescent lamp in which the primary light source i5 a phosphor material.
Another s~ cant candidate for a lamp ~o replace the incandescent ~ulb is the ~ ~ developed by ~he pre~ent assignee. ~ ~ is a trad~ark of the General Electric Company, Cleveland~ OH, In this lamp, the light output is provided solely by the ~islble electromagne~ic radlation frGm the arc discharge tube itself, which is 20 surrounded by an outer jacket for protectiorl and for the~nal insulation purposes. In ~he HALARC~) lamp, the ra~ed ou~pu~
color spectra is a function solely o~ the arc tube ingredien~s and the operating conditions, Lastly, another possible replacemen~ ~or the 25 in andescent lamp lncludPs such lamps as the folded discharge l~mp, in which a converltional fluorescent lamp is desi~ned and built with a long discharge path length formed by folding or otherwise reconfiguring the discharge ~ube, .
~)S ~ ~3 A signific.ant difference between ~he lamp of ~he present invention and other lamp designs is that, in the lamp of the presen~ invention, ~he arc discharge ultraviolet source is physically isolated from the phosphor as opposed ~o 05 conventional fluorescent lamps where the glow discharge ultravioLet source is in contact wi~h the phosp~or.
Accordingly, the glass part of a convelltional 1uorescen~ l~mp may be best be described as a discharge envelope. The glass employed in such a lamp ~s not cri~ical. Howeve~, in lamps which produc~. their prlmary ~isible light output f~om an arG
discharge, rather than from a phosphor, the arc tube mNs~
typically be operated at relatively high temperature rangin~
for example, from approximately 400 C to approxim~tely 900 C. For sueh high ~emperatures hard glasses may be-required, particularly for temperatures in ex~ess of approximately 700C, At lower opera~ng temperatures, say for example 600 C, a softer, less expensi~e glass may be ~mployed for the arc tube~ ~dditionally, con~entional fluoresce~lt l~mps generally operate at a total internal vapor pressure of less than 3 torr, This vapor pre~sure ar~ses fr~m a partial pressure o~ less than approximately 3 ~orr for argon and a partial pressure of mercury of between 1 a~d 10 millitorr. In contrast, l~mps of the presen~ i~ven~ion pre~erably operate with total arc tube vapor pressure of between app~ox~ma~ely 1~0 and approx~mately 3000 torr. This ~o~al pre~sure arises from partial pressures o argon, mercury and copper halide.
~ 3 Ano~her lamp ha~in~ a structure resembling the present invention ls the so-called color-corrected mercury lamp. In this lamp at least 80 percent of the light ou~put is from a mercury arc. There is also presen~ some light output 05 fr~m a phosphor coatlng an exterior enclosing envelope.
Ho~ever, in such l~mps only about 10 to 15 pereent of the light output is due to the phosphor coating. Such lam~s use ~he phosphor to ~odify the color perception of the light produced by the arc. In such lamps the ultra~iolet ou~p~ttfrom 10 the arc tube i5 low. In contrast, the ultraviole~ ou~pu~
of the present invention is enhanced and controlled to produce ul~ra~iolet radiation having ~pecific wavelengths (typically ln excess of 300 nanometers) to promote transmissi~ity thro~gh glas~, notably the harder glasses. This pr~motes con~rollable light production fr~m the phosphor and from the arc ~oo.
~ nother si~nificant fact concerning ~he presen~
~nYention is that glass is ~ften not vei~ tran~missi~e for ultra~lole~ radiation. Accordingly, thç selection o radiating discharge medium species which may be ineluded in the arc tu~e is not trivial. Not only ~st the species radia~e a~ the proper wa~elength to assure opt~mum ~rans-mi~sivity throùgh the arc tube, but it should a~so radiate in a fairly narrow band of the spectrum in order ~o provide higher e~flciencies. Further more, the discharge medium mNst be easy to work with and nonreacti~e with the arc ; tube material e~ployed. Furthermore, the ~apor pres~res o the radiating species employed should have desir~ble values within the range of operating temperatures employed.
~ Z~5 8 ~ ~
Summary of the Invention In accordance wq~h a preferred embod~ment of the present in~ention a fluorescent arc lamp c~mprises a gas~
tight, ultraviolet-transmissive arc tube wl~h electrodes 05 dlsposed in either end, and an exterior visible-light ~ransmis-siYe gas-tight en~elope en~losing the arc tube; the envelope, having an ultraYiolet ~ensitive phosphor eoated thereon w~th conductors disposed through the envelope for electrical eonnection between said electrodes and an ex ernal s~uroe of electrical energy. F~rthermore? in accordance with this embodiment the arc tube has disposed therein a vaporizable discharge medi~m camprising materials selected from the halides of copper, silver, and rhenium.
Furthenmore, in accordance with a furthe~ em~odimen~
of the present invention, mercury is also disposed within the arc tube. The use of varying proportions o mercu~y within the arc tube permits the construction of an e~tire range of combination "fluorescent/arc-discharge lamps in which the visible radiation is pr~duced not only from the phosp~or, but also from the arc discharge wi~hin the arc ~u~e itself. By increasing the pro~o ~ ion of mercury wi~hin the arc ~ube, the lamp of the present i~vention tends to exhibit lamp eharaeteristics more closely assoelated with lamps whose sole visible light outpu~ ar Pes from the arc discharge itself.
~ ccordi~gly, it is an object of the pre~ent inYPntion to pro~de an efficient re~lacement for the incan-d~cent lam~.
~ ~05 ~ 3 .
It is a further object of the prese~t inventisn to provide 8 combination fluorescent and ~rc discharge lamp in which the arc discharge is physically isolated from the phosphor.
05 . It is also an object of the prese~t in~ention to providP a range of lamp~ in which the proportion of li~h~
produced by the arc dlscharge as compared to the portion produced by ~he radiating phosp~or, can be varied.
Las~ly, in sum it is an object o~ the presen~
~- 10 invention to produce an eficient long life l~mp, operable ~n a~y position.
Descripti n of the Fi~u~es The subjec~ matter which is regarded as the in~ention i9 particularly pointed out and dis~inctly claimed in ~he ~15 concluding portion of the specification. The inven~ion, b~t~ as to organization and method of practice, together with further objec~s and advantages thereof, ma~ besll: be unders~ood by reference t~, the following description ~aken in connection with the accompanying drawings in which:
FIGURE 1 is a partial cross-sec~ional side eleYatio~
vi~w of a la~..p ~.anufactured in aecordance with the pre3en~
~vention.
. FIGUR~ 2 is a partial cross-sectional side elevation vlew lllustrating a detailed view o the arc tube ~wn in FIG. 1.
.
FIG. 1 illustrates one embodimen~ of the present ~nvention in ~hich the outer jacket 12 and a~c tube 20 are conigure~ ln the general size and shape of the above-described HALAR ~ lamp. ~owever, the lamp of the pre3en~
` inven~ion may a~sume a lar~e range of sîzes and shapes.
~ . .
-~L~O~ 3 - In FI(:. 1, lamp 10 is seen to possess an outer jacket or envelope 12 having interior phosphor coat 14. The exterior e~velope 12 is gas-tight and transmissive to light at visible waveleng~hs, at ~east in those embodiments of 05 the present i~vention in which phosphor 14 is disposed on the interior of the envelope. Outer jacke~ 12 m~y be co~veniently fastened to base 17, Envelope 12 surrounds arc tube 20, which is more particularly described and discuss~d in FIG. 2 below.
Arc tube 20 is a source of radiation at specific ultraviolet wavelenths and m~y comprise either relatively hard or relati~ely soft glass depending upon the operating temperature of the lamp. Arc tube 20 is supported within jacket 12 by means o~ stiff electrode lead~ 18 and 19, as shown in F~G. 1.
Leads 18 and 19 are also electrically and mecha~ically connected to leads 16, which pass through the w~ll of jacket 12.
In a preferred embodimen~ of the presen~ in~ention jacke~ 12 .. . . ., ......................................... . .. _ _ include~ a relatively thiek glass base 17, through whl~h elect~ode leads 16 pass and which also serves as a stable
C~.PP.~-ARC EXCI~ATION
Back~round of the ImTention This invention rela~es ~o fluorescent lamps and more parti::ularly to fluorescen~ lamps corltainiTIg an interior arc discharge tube. Moreove~, the present in~ention also 0~ relates to a combination fluorescent and arc discharge lamp in which the l~ght ou~put may be var;ed as between light from ~che arc an~ light from the p~osp~o~.
At present) much of present-day lighting needs axe supplied throu~ the use of iFIefficient incandeseent la~ap~.
While these lamps are relatively in~cpensive and are produced~ in large quantities with knowrl technolo8;y, nonet:hele~s the increasing cost of electric energy has, in rece~ years, chaDged the econo~nic situation. In particular, i the cost of operating ~ncandescent lamps is considered, along with their relat~vely short lifetimes, the incandescen~
~ may be uneconomical in certain situations parti ularly those in which they are compared agalnst long life, high effi-ciency lamps. A number of different kinds of lamp geometries and designs have at~empted to ulill this need, Conventional fluoresee~t lamps, in wh~eh the vi~ible radiation is prod~ced by a phosphor coating on the nterior of a partially evacuated disrharge tube, are eficient and long lived but lack the geometry necessary or use in standard luminaires and fixture~s, ~' ""~, :llZ()5~3 Another potential incandescent lamp replacement is the solenoidal elec~cric field lamp (Sl:F ~ amp) which is similar in operation to a fluorescent lamp but in which an electronic ballast drives a ferrite core disposed wi~hin 05 an arc discharge medium to produce ultraviolet radia~ion which impi~ges upon a phosphor coate~ upon the 1æmp tu~P
w~ll S9 as to produce the des~red radiation. Ihese lamps are smallt c~mpact and, with an appropriate electronic ball~st, easily replace the con~entisnal incandescent lamp in most fixture~/ It is not, h~wever, an arc lam~ in which the prlmary llght source ls from the arc discharge, Rather, it is a fluorescent lamp in which the primary light source i5 a phosphor material.
Another s~ cant candidate for a lamp ~o replace the incandescent ~ulb is the ~ ~ developed by ~he pre~ent assignee. ~ ~ is a trad~ark of the General Electric Company, Cleveland~ OH, In this lamp, the light output is provided solely by the ~islble electromagne~ic radlation frGm the arc discharge tube itself, which is 20 surrounded by an outer jacket for protectiorl and for the~nal insulation purposes. In ~he HALARC~) lamp, the ra~ed ou~pu~
color spectra is a function solely o~ the arc tube ingredien~s and the operating conditions, Lastly, another possible replacemen~ ~or the 25 in andescent lamp lncludPs such lamps as the folded discharge l~mp, in which a converltional fluorescent lamp is desi~ned and built with a long discharge path length formed by folding or otherwise reconfiguring the discharge ~ube, .
~)S ~ ~3 A signific.ant difference between ~he lamp of ~he present invention and other lamp designs is that, in the lamp of the presen~ invention, ~he arc discharge ultraviolet source is physically isolated from the phosphor as opposed ~o 05 conventional fluorescent lamps where the glow discharge ultravioLet source is in contact wi~h the phosp~or.
Accordingly, the glass part of a convelltional 1uorescen~ l~mp may be best be described as a discharge envelope. The glass employed in such a lamp ~s not cri~ical. Howeve~, in lamps which produc~. their prlmary ~isible light output f~om an arG
discharge, rather than from a phosphor, the arc tube mNs~
typically be operated at relatively high temperature rangin~
for example, from approximately 400 C to approxim~tely 900 C. For sueh high ~emperatures hard glasses may be-required, particularly for temperatures in ex~ess of approximately 700C, At lower opera~ng temperatures, say for example 600 C, a softer, less expensi~e glass may be ~mployed for the arc tube~ ~dditionally, con~entional fluoresce~lt l~mps generally operate at a total internal vapor pressure of less than 3 torr, This vapor pre~sure ar~ses fr~m a partial pressure o~ less than approximately 3 ~orr for argon and a partial pressure of mercury of between 1 a~d 10 millitorr. In contrast, l~mps of the presen~ i~ven~ion pre~erably operate with total arc tube vapor pressure of between app~ox~ma~ely 1~0 and approx~mately 3000 torr. This ~o~al pre~sure arises from partial pressures o argon, mercury and copper halide.
~ 3 Ano~her lamp ha~in~ a structure resembling the present invention ls the so-called color-corrected mercury lamp. In this lamp at least 80 percent of the light ou~put is from a mercury arc. There is also presen~ some light output 05 fr~m a phosphor coatlng an exterior enclosing envelope.
Ho~ever, in such l~mps only about 10 to 15 pereent of the light output is due to the phosphor coating. Such lam~s use ~he phosphor to ~odify the color perception of the light produced by the arc. In such lamps the ultra~iolet ou~p~ttfrom 10 the arc tube i5 low. In contrast, the ultraviole~ ou~pu~
of the present invention is enhanced and controlled to produce ul~ra~iolet radiation having ~pecific wavelengths (typically ln excess of 300 nanometers) to promote transmissi~ity thro~gh glas~, notably the harder glasses. This pr~motes con~rollable light production fr~m the phosphor and from the arc ~oo.
~ nother si~nificant fact concerning ~he presen~
~nYention is that glass is ~ften not vei~ tran~missi~e for ultra~lole~ radiation. Accordingly, thç selection o radiating discharge medium species which may be ineluded in the arc tu~e is not trivial. Not only ~st the species radia~e a~ the proper wa~elength to assure opt~mum ~rans-mi~sivity throùgh the arc tube, but it should a~so radiate in a fairly narrow band of the spectrum in order ~o provide higher e~flciencies. Further more, the discharge medium mNst be easy to work with and nonreacti~e with the arc ; tube material e~ployed. Furthermore, the ~apor pres~res o the radiating species employed should have desir~ble values within the range of operating temperatures employed.
~ Z~5 8 ~ ~
Summary of the Invention In accordance wq~h a preferred embod~ment of the present in~ention a fluorescent arc lamp c~mprises a gas~
tight, ultraviolet-transmissive arc tube wl~h electrodes 05 dlsposed in either end, and an exterior visible-light ~ransmis-siYe gas-tight en~elope en~losing the arc tube; the envelope, having an ultraYiolet ~ensitive phosphor eoated thereon w~th conductors disposed through the envelope for electrical eonnection between said electrodes and an ex ernal s~uroe of electrical energy. F~rthermore? in accordance with this embodiment the arc tube has disposed therein a vaporizable discharge medi~m camprising materials selected from the halides of copper, silver, and rhenium.
Furthenmore, in accordance with a furthe~ em~odimen~
of the present invention, mercury is also disposed within the arc tube. The use of varying proportions o mercu~y within the arc tube permits the construction of an e~tire range of combination "fluorescent/arc-discharge lamps in which the visible radiation is pr~duced not only from the phosp~or, but also from the arc discharge wi~hin the arc ~u~e itself. By increasing the pro~o ~ ion of mercury wi~hin the arc ~ube, the lamp of the present i~vention tends to exhibit lamp eharaeteristics more closely assoelated with lamps whose sole visible light outpu~ ar Pes from the arc discharge itself.
~ ccordi~gly, it is an object of the pre~ent inYPntion to pro~de an efficient re~lacement for the incan-d~cent lam~.
~ ~05 ~ 3 .
It is a further object of the prese~t inventisn to provide 8 combination fluorescent and ~rc discharge lamp in which the arc discharge is physically isolated from the phosphor.
05 . It is also an object of the prese~t in~ention to providP a range of lamp~ in which the proportion of li~h~
produced by the arc dlscharge as compared to the portion produced by ~he radiating phosp~or, can be varied.
Las~ly, in sum it is an object o~ the presen~
~- 10 invention to produce an eficient long life l~mp, operable ~n a~y position.
Descripti n of the Fi~u~es The subjec~ matter which is regarded as the in~ention i9 particularly pointed out and dis~inctly claimed in ~he ~15 concluding portion of the specification. The inven~ion, b~t~ as to organization and method of practice, together with further objec~s and advantages thereof, ma~ besll: be unders~ood by reference t~, the following description ~aken in connection with the accompanying drawings in which:
FIGURE 1 is a partial cross-sec~ional side eleYatio~
vi~w of a la~..p ~.anufactured in aecordance with the pre3en~
~vention.
. FIGUR~ 2 is a partial cross-sectional side elevation vlew lllustrating a detailed view o the arc tube ~wn in FIG. 1.
.
FIG. 1 illustrates one embodimen~ of the present ~nvention in ~hich the outer jacket 12 and a~c tube 20 are conigure~ ln the general size and shape of the above-described HALAR ~ lamp. ~owever, the lamp of the pre3en~
` inven~ion may a~sume a lar~e range of sîzes and shapes.
~ . .
-~L~O~ 3 - In FI(:. 1, lamp 10 is seen to possess an outer jacket or envelope 12 having interior phosphor coat 14. The exterior e~velope 12 is gas-tight and transmissive to light at visible waveleng~hs, at ~east in those embodiments of 05 the present i~vention in which phosphor 14 is disposed on the interior of the envelope. Outer jacke~ 12 m~y be co~veniently fastened to base 17, Envelope 12 surrounds arc tube 20, which is more particularly described and discuss~d in FIG. 2 below.
Arc tube 20 is a source of radiation at specific ultraviolet wavelenths and m~y comprise either relatively hard or relati~ely soft glass depending upon the operating temperature of the lamp. Arc tube 20 is supported within jacket 12 by means o~ stiff electrode lead~ 18 and 19, as shown in F~G. 1.
Leads 18 and 19 are also electrically and mecha~ically connected to leads 16, which pass through the w~ll of jacket 12.
In a preferred embodimen~ of the presen~ in~ention jacke~ 12 .. . . ., ......................................... . .. _ _ include~ a relatively thiek glass base 17, through whl~h elect~ode leads 16 pass and which also serves as a stable
2~ pla~f~rm for fixedly mounting arc tube 20 wlthin jacke~ 12.
As is conventionally known in the art, elèctrodes 16 ~yp~cally co~prise or are coated with a meta~ composition.
such a to which the glass in platform 17 is particularly adherent. In this way the gas-tlght integrity of ou~er en~7elope 12 is maintained. As is also well-known in the l~mp arts, electrodes 16 are coupled in a conv~entional manner to an appropriate electronic ballast which opera~e~
~o supply starting and running voltage for ~hé lamp.
8'~3 A number of phosphors might be employed as an interior coating on ~acket 12. The principle requirement for these phosphors is that they absorb radiation in the ultraviolet region and reradiate visible light. For example, 05 but without limitation, these phosphors may include such compounds as yttrium vanadate doped with europium (YV04:Eu), zinc silicate-germanate doped with manganese ~n2(SiGe)O4:Mn, and magnesium germanate doped with manganese (MgGeO4:Mn).
Space 15 between arc tube 20 and outer envelope 12 preferably comprises a vacuum for the above-mentioned phosphor ma-terials.
A vacuum is also preferred whenever a phosphor coating 14 is employed in which the phosphor is most efficient when operating at or near room tempera-~ure. In other embodiments of the invention in which phosphor coatings 14 are employed for which the phosphor exhibits higher efficiencies at elevated temperatures, space 15 preferably includes inert gas such as nitrogen or argon so that some convective and/or conductive heat flow may be provided to the phosphor coating to permit arc tube 20 to provide the desired operating temperature for the phosphor coating.
FIG. 2 more particularly describes the construction of arc tube assembly 20 which preferably comprises a gas-tight ultraviolet transmissive tube 22 with an interior space 28 having electrodes 24 exposed at either end thereof.
Electrodes 24 may actually comprise enlargements of the ends of electrode leads 18 and 19 which are disposed -through the arc tube 22. In order to provide a gas-tight seal, a portion of leads 18 and 19 is a foil of metal 21 which is specifically chosen to form a gas-tight adhesive bond both to the metal of the ~ 3~'~3 electrode leads and to the glass of the arc tube. Such foil 21 typically comprises molybdenum.
A significant aspect of the present invention ls the inclusion within the arc ~ube of an appropria~e ~mount 05 o a vaporiza~le discharge medium. For ex~ple, ~his medium may.be disposed within the arc tube 20 as a pe~let 30. In accordance with a preferred embodiment of ~he present inven~ion the discharge medium comprises either copper hal~de, rhenium halide, or silver halide. Howe~er~ co~per halide is ~he preferred choice since rhenium and silver are no$ as easy to work with in their halides forms. ~owever, ei~her copper bromide or copper iodide may be e~ployed to produce the desired ultraviolet ou~put from arc ~ube 20. Copper ro~ the halides exhib~ts a s~rong and efficien~ ou~pu~
at a wavelength of 327.4 and 324.7 nan~metexs. Furthermore, e~en though ~heir halide~ may be dificult to work with, bot.h rh~nium and silver exhibit ultraviolet radiation at appropriate ~avelengths and may be employed in the lamp of the prese~t inve~tion, In particular~ rhenium exhibi~ ul~ra~
vlolet radiation ha~ ng a wavelength of 346.5 nan~meters.
Likewlse, silver exhibits ultraviolet radiation at a wave length of 328 nanometers. Magnesium has been sugges~ed in ~he past as a radiating species; howe~er~ magnesium has a s~rong resonance line at 285.2 naometers, bu~ this radia~ion is absorbed by mos~ plastics and glasses m~king i~
ess desirable for the use in ~he present inven~ion.
For example, i copper iodide is em~loyed in pellet 30, and if the lamp is operated at a reservoir temperature between approximately 500 C and approx~m~ely S8~3 900C, the copper iodide exhibits respectively correspondiny vapor pressures of between approximately 1 and approximately 100 torr. However, the preferred operating temperature of the present lamp is approximately 600C. At this temperature 05 an arc tube comprising relatively expensive fused quartz is not required and a less expensive, hard glass may be used for arc tube 20.. Additionally, it is also desirable to add small amounts of argon or other noble gas to arc tube 20 for the purpose of facilitating lamp starti~g. However, such noble gases may be added for other purposes and in amounts which vary according to the function desired.
I~ one preferred embodiment of ~he pxesent inve~-tion, copper halide is added to arc tube 20-along or with small amounts of noble gases. In such an embodiment, arc tube 20 generates ultraviolet radiation at a wavele~gth which readily passes through the glass of arc tube 20 to impinge upon phosphor 14 on the inner wall of jacket 1~. Accordingly, in this embodiment all of the vi~ible waveleng~h outpu~ is du~
to-the phosphor. However, i~ should be appreciated that the lamp of this embodiment is not only a fluorescent lamp but it is also, in fact, an arc discharge lamp and is thus re~erred to herein as a fluorescent~arc-discharge lamp.
.. In accordance with another significant embodiment of the present invention, arc tube 20 m~y also contain small r ~ 25 am~unts of mercury, such as may be supplied by droplet 26 disposed within arc tube 20. The amount of mercury chosen is generally sufficient to maintain a partial mercury vapor pres-sure of from about 0.1 to 10 atmospheres at operating temper atures. m e use of mercury as an added species in the S !3~3 discharge medium significantly alters the nature of the lamp.
In particular, with increasing amounts of mercury disposed within arc tube 20, more and more visible wavelength rad-iation is produced within the arc tube. ~hus it has been 05 found that under certain operating conditions and proportions of ccpper iodide and merc~lry, significant amounts of visible radiation come from mercury in the discharg~, as well as from surrounding phosphor 14. Under other conditions, the mercury radiation may be suppressed, resulting in behavior . 10 re closely resembling that o~ a conventional fluorascent lamp rather than in behavior describable as a combination fluorescent and arc.lamp. Thus based on arc tube ingredients and operating conditions, a whole range of lamps combining light output from arc and phosphors excited from ultraviolet radiation from the arc is possible. Near tha arc-end o~ this range of lam~ behaviors, lamp~ of the present invention become similar to color-corrected mexcury lamp5 in which about 10 to 15 percent of the light output arises from the pho~phor. In the present lamp, however, at least 20% of the ~- ~O vt~ible light output is derived from the phosphor. At ~h other end of this behavior range is the above-described embodi-ment of the present invention in which only silver, copper, or rhenium halides are employed as ultraviolet radiating species.
In the lamp~ of the present invention, the copper, rhenium or silver halide is added in a quantity, depending on volume, sufficient to produce a partial vapor pressure of ~ from about 1 to about lO0 torr corresponding to reservoir ; operating temperatures between about 500 to about 900~C, ~LZ~)S~3~3 typically between about 0.05 mg/cc and 2 ms/cc of arc tube volume. If mercury is used as an additive, it is chosen to be present in an amount t~ produce a partial vapor pressure between about 0.1 and about 10 atmospheres~ For argon9 vapor 05 pressures of from about 2 to about 100 torr are employed for the purpose of improved lamp starting characteristics, as is conventionally known.
While the preferred embodiment of the present invention disposes phosphor 14 on the interior of jacket 12, it is also possible to employ a phosphor coating on ~he exterior of jacket 12. If such a configuration is employed~
it is~ of course, d2sirab1e that the glass of envelope 12 be transmissive to the ultraviolet radiation from arc tube 20.
Moreover, in this con~iguration it is also desirable th~t ~ 15 some form of protective coating, such as clear plastic or glass, be disposed over the phos~hor.
There are a number of features of the present invention which provide significant improvement over o~her : light sources. In particular, the arc from the copper halides . 20 produces resonance radiation very efficiently~ The o~her copper radiation lines are very feeble compared to the reso-nance lines at wavelengths of 324.7 and 327.4 nanometers.
Additionally, the vapor pressures of copper iodide and copper bromide are several torr at 600~C and thus the arc tubes o~
the present invention may be operated at this temperature rather than the 750C temperature usually re~uired for meta~
halide lamp~. This lower temperature further serves to reduce the loss caused by infrared incandescence of the axc tube. In particular ! in the present invention this loss is ~ ~ S ~ ~ 3 cut in half. Moreo~er, the lower operating tempera~re permits the use of a softer ~lass, such as borosilica~e glass, in place of a ~used quar~z arc tube since this and simila~ glasses may be used at temperatures up to abou~
05 700Q C. At the same t~me, these glasses transmit the relatively long waveleng~h ultraviolet at approxima~ely 32S
nanometer with negligible at~enustion. ~he use of these glasses in place of fused quartz reduces bo~h ~aterial a~d abrica~ion costs. Also, the lower heat loss reduces io heating of adjacent electronic components w~ich may be employed in an attached ballast assembly. ~fficiency is - also ~mproved over conventional fluorescent l~mps because the energy lost in conver~ing a 326 nanome~er light qu~tum to a 555 nan~meter visible light quantum is only 1.2 electron lS vol~s as compared to the 2,1 eleetron volt loss incurred in converting 254 nanometer wavelengths to visible radia~ion, Whlle theconcept of employing longer wavelength ul~raviole~
rad~a~ion sources to reduce quantum lo~s ha3 been proposed be~ore, i~ has also been shown that the propo~ed use of cadmium to effect this reduction actu~lly results in no impro~ment in efficiency because long waYele~gth ult~aviolet is only a small part of the radiated output for cadmium, See the article titled '~ow-Pressure High-Current Cadmium Vapor Discharge in the Middle Ultraviolet" in Yolume 49, page 553 of the Journal o~ Applied Physics ~1978), by Peter D. J~hnson.
:
In the present invention, since the required vapor pressure of copper halide is easy to attain and ~he arc is based on a single radia~ing component system, ~he output of the lamp is independent of operating position.
~5 Furthermore, copper halides are che~ically ~able and do not react with arc tube components. Additionally, they are non-h~groscopic which simplifies l~mp fabrication. A further improvement ~co be noted in the copper fluorescent arc lamp is ~he fact ~hat the pho~phor is isolated rom the discharge.
10 As opposed to conventional fluorescent lamp~, the environment of the phosphor, vacuu~ and inert ga~ can be selected independently thereby eli~ nating phosphor de~eriora-tion due to the presence of mercury atoms or ions, electron~, or very short wavele~gth ultrav~olet radi~tion, From the abo~e it may be apprecia~ed that ~he lamp of the presen~ invention provides a unique and no~el l~mp whic~ acts as an efficient, long lived replacemen~ for the conventional incandes ent lamp. ~oreover, t~rough the add~-t~-on of varying amo~nts of mercury wi~hin the arc ~u~e, a whole range of lamps may be fabrica~ed in accordance`with ~he present inven~ion.
. While the invention has been described in detail herein, in accordance with cer~ain preferred embodime~ts thereof, many modifications and changes therein may ~e effected by those ~killed în the art, Accordingly, it is intended by the appended claims to cover a~l such modifications and change~ as fall withi~ the true spirit of the in~en~ion.
.. .
As is conventionally known in the art, elèctrodes 16 ~yp~cally co~prise or are coated with a meta~ composition.
such a to which the glass in platform 17 is particularly adherent. In this way the gas-tlght integrity of ou~er en~7elope 12 is maintained. As is also well-known in the l~mp arts, electrodes 16 are coupled in a conv~entional manner to an appropriate electronic ballast which opera~e~
~o supply starting and running voltage for ~hé lamp.
8'~3 A number of phosphors might be employed as an interior coating on ~acket 12. The principle requirement for these phosphors is that they absorb radiation in the ultraviolet region and reradiate visible light. For example, 05 but without limitation, these phosphors may include such compounds as yttrium vanadate doped with europium (YV04:Eu), zinc silicate-germanate doped with manganese ~n2(SiGe)O4:Mn, and magnesium germanate doped with manganese (MgGeO4:Mn).
Space 15 between arc tube 20 and outer envelope 12 preferably comprises a vacuum for the above-mentioned phosphor ma-terials.
A vacuum is also preferred whenever a phosphor coating 14 is employed in which the phosphor is most efficient when operating at or near room tempera-~ure. In other embodiments of the invention in which phosphor coatings 14 are employed for which the phosphor exhibits higher efficiencies at elevated temperatures, space 15 preferably includes inert gas such as nitrogen or argon so that some convective and/or conductive heat flow may be provided to the phosphor coating to permit arc tube 20 to provide the desired operating temperature for the phosphor coating.
FIG. 2 more particularly describes the construction of arc tube assembly 20 which preferably comprises a gas-tight ultraviolet transmissive tube 22 with an interior space 28 having electrodes 24 exposed at either end thereof.
Electrodes 24 may actually comprise enlargements of the ends of electrode leads 18 and 19 which are disposed -through the arc tube 22. In order to provide a gas-tight seal, a portion of leads 18 and 19 is a foil of metal 21 which is specifically chosen to form a gas-tight adhesive bond both to the metal of the ~ 3~'~3 electrode leads and to the glass of the arc tube. Such foil 21 typically comprises molybdenum.
A significant aspect of the present invention ls the inclusion within the arc ~ube of an appropria~e ~mount 05 o a vaporiza~le discharge medium. For ex~ple, ~his medium may.be disposed within the arc tube 20 as a pe~let 30. In accordance with a preferred embodiment of ~he present inven~ion the discharge medium comprises either copper hal~de, rhenium halide, or silver halide. Howe~er~ co~per halide is ~he preferred choice since rhenium and silver are no$ as easy to work with in their halides forms. ~owever, ei~her copper bromide or copper iodide may be e~ployed to produce the desired ultraviolet ou~put from arc ~ube 20. Copper ro~ the halides exhib~ts a s~rong and efficien~ ou~pu~
at a wavelength of 327.4 and 324.7 nan~metexs. Furthermore, e~en though ~heir halide~ may be dificult to work with, bot.h rh~nium and silver exhibit ultraviolet radiation at appropriate ~avelengths and may be employed in the lamp of the prese~t inve~tion, In particular~ rhenium exhibi~ ul~ra~
vlolet radiation ha~ ng a wavelength of 346.5 nan~meters.
Likewlse, silver exhibits ultraviolet radiation at a wave length of 328 nanometers. Magnesium has been sugges~ed in ~he past as a radiating species; howe~er~ magnesium has a s~rong resonance line at 285.2 naometers, bu~ this radia~ion is absorbed by mos~ plastics and glasses m~king i~
ess desirable for the use in ~he present inven~ion.
For example, i copper iodide is em~loyed in pellet 30, and if the lamp is operated at a reservoir temperature between approximately 500 C and approx~m~ely S8~3 900C, the copper iodide exhibits respectively correspondiny vapor pressures of between approximately 1 and approximately 100 torr. However, the preferred operating temperature of the present lamp is approximately 600C. At this temperature 05 an arc tube comprising relatively expensive fused quartz is not required and a less expensive, hard glass may be used for arc tube 20.. Additionally, it is also desirable to add small amounts of argon or other noble gas to arc tube 20 for the purpose of facilitating lamp starti~g. However, such noble gases may be added for other purposes and in amounts which vary according to the function desired.
I~ one preferred embodiment of ~he pxesent inve~-tion, copper halide is added to arc tube 20-along or with small amounts of noble gases. In such an embodiment, arc tube 20 generates ultraviolet radiation at a wavele~gth which readily passes through the glass of arc tube 20 to impinge upon phosphor 14 on the inner wall of jacket 1~. Accordingly, in this embodiment all of the vi~ible waveleng~h outpu~ is du~
to-the phosphor. However, i~ should be appreciated that the lamp of this embodiment is not only a fluorescent lamp but it is also, in fact, an arc discharge lamp and is thus re~erred to herein as a fluorescent~arc-discharge lamp.
.. In accordance with another significant embodiment of the present invention, arc tube 20 m~y also contain small r ~ 25 am~unts of mercury, such as may be supplied by droplet 26 disposed within arc tube 20. The amount of mercury chosen is generally sufficient to maintain a partial mercury vapor pres-sure of from about 0.1 to 10 atmospheres at operating temper atures. m e use of mercury as an added species in the S !3~3 discharge medium significantly alters the nature of the lamp.
In particular, with increasing amounts of mercury disposed within arc tube 20, more and more visible wavelength rad-iation is produced within the arc tube. ~hus it has been 05 found that under certain operating conditions and proportions of ccpper iodide and merc~lry, significant amounts of visible radiation come from mercury in the discharg~, as well as from surrounding phosphor 14. Under other conditions, the mercury radiation may be suppressed, resulting in behavior . 10 re closely resembling that o~ a conventional fluorascent lamp rather than in behavior describable as a combination fluorescent and arc.lamp. Thus based on arc tube ingredients and operating conditions, a whole range of lamps combining light output from arc and phosphors excited from ultraviolet radiation from the arc is possible. Near tha arc-end o~ this range of lam~ behaviors, lamp~ of the present invention become similar to color-corrected mexcury lamp5 in which about 10 to 15 percent of the light output arises from the pho~phor. In the present lamp, however, at least 20% of the ~- ~O vt~ible light output is derived from the phosphor. At ~h other end of this behavior range is the above-described embodi-ment of the present invention in which only silver, copper, or rhenium halides are employed as ultraviolet radiating species.
In the lamp~ of the present invention, the copper, rhenium or silver halide is added in a quantity, depending on volume, sufficient to produce a partial vapor pressure of ~ from about 1 to about lO0 torr corresponding to reservoir ; operating temperatures between about 500 to about 900~C, ~LZ~)S~3~3 typically between about 0.05 mg/cc and 2 ms/cc of arc tube volume. If mercury is used as an additive, it is chosen to be present in an amount t~ produce a partial vapor pressure between about 0.1 and about 10 atmospheres~ For argon9 vapor 05 pressures of from about 2 to about 100 torr are employed for the purpose of improved lamp starting characteristics, as is conventionally known.
While the preferred embodiment of the present invention disposes phosphor 14 on the interior of jacket 12, it is also possible to employ a phosphor coating on ~he exterior of jacket 12. If such a configuration is employed~
it is~ of course, d2sirab1e that the glass of envelope 12 be transmissive to the ultraviolet radiation from arc tube 20.
Moreover, in this con~iguration it is also desirable th~t ~ 15 some form of protective coating, such as clear plastic or glass, be disposed over the phos~hor.
There are a number of features of the present invention which provide significant improvement over o~her : light sources. In particular, the arc from the copper halides . 20 produces resonance radiation very efficiently~ The o~her copper radiation lines are very feeble compared to the reso-nance lines at wavelengths of 324.7 and 327.4 nanometers.
Additionally, the vapor pressures of copper iodide and copper bromide are several torr at 600~C and thus the arc tubes o~
the present invention may be operated at this temperature rather than the 750C temperature usually re~uired for meta~
halide lamp~. This lower temperature further serves to reduce the loss caused by infrared incandescence of the axc tube. In particular ! in the present invention this loss is ~ ~ S ~ ~ 3 cut in half. Moreo~er, the lower operating tempera~re permits the use of a softer ~lass, such as borosilica~e glass, in place of a ~used quar~z arc tube since this and simila~ glasses may be used at temperatures up to abou~
05 700Q C. At the same t~me, these glasses transmit the relatively long waveleng~h ultraviolet at approxima~ely 32S
nanometer with negligible at~enustion. ~he use of these glasses in place of fused quartz reduces bo~h ~aterial a~d abrica~ion costs. Also, the lower heat loss reduces io heating of adjacent electronic components w~ich may be employed in an attached ballast assembly. ~fficiency is - also ~mproved over conventional fluorescent l~mps because the energy lost in conver~ing a 326 nanome~er light qu~tum to a 555 nan~meter visible light quantum is only 1.2 electron lS vol~s as compared to the 2,1 eleetron volt loss incurred in converting 254 nanometer wavelengths to visible radia~ion, Whlle theconcept of employing longer wavelength ul~raviole~
rad~a~ion sources to reduce quantum lo~s ha3 been proposed be~ore, i~ has also been shown that the propo~ed use of cadmium to effect this reduction actu~lly results in no impro~ment in efficiency because long waYele~gth ult~aviolet is only a small part of the radiated output for cadmium, See the article titled '~ow-Pressure High-Current Cadmium Vapor Discharge in the Middle Ultraviolet" in Yolume 49, page 553 of the Journal o~ Applied Physics ~1978), by Peter D. J~hnson.
:
In the present invention, since the required vapor pressure of copper halide is easy to attain and ~he arc is based on a single radia~ing component system, ~he output of the lamp is independent of operating position.
~5 Furthermore, copper halides are che~ically ~able and do not react with arc tube components. Additionally, they are non-h~groscopic which simplifies l~mp fabrication. A further improvement ~co be noted in the copper fluorescent arc lamp is ~he fact ~hat the pho~phor is isolated rom the discharge.
10 As opposed to conventional fluorescent lamp~, the environment of the phosphor, vacuu~ and inert ga~ can be selected independently thereby eli~ nating phosphor de~eriora-tion due to the presence of mercury atoms or ions, electron~, or very short wavele~gth ultrav~olet radi~tion, From the abo~e it may be apprecia~ed that ~he lamp of the presen~ invention provides a unique and no~el l~mp whic~ acts as an efficient, long lived replacemen~ for the conventional incandes ent lamp. ~oreover, t~rough the add~-t~-on of varying amo~nts of mercury wi~hin the arc ~u~e, a whole range of lamps may be fabrica~ed in accordance`with ~he present inven~ion.
. While the invention has been described in detail herein, in accordance with cer~ain preferred embodime~ts thereof, many modifications and changes therein may ~e effected by those ~killed în the art, Accordingly, it is intended by the appended claims to cover a~l such modifications and change~ as fall withi~ the true spirit of the in~en~ion.
.. .
Claims (15)
1. A fluorescent/arc-discharge lamp comprising:
a gas-tight, ultraviolet transmissive arc tube having electrodes disposed therein at either end thereof;
an exterior, visible light transmissive, gas-tight envelope enclosing said arc tube, said envelope having an ultraviolet sensitive phosphor disposed thereon and electrical conductors disposed therethrough and connected to said electrodes; and A vaporizable discharge medium disposed within said arc tube, said medium comprising material selected from the group consisting of copper halides, rhenium halides and silver halides.
a gas-tight, ultraviolet transmissive arc tube having electrodes disposed therein at either end thereof;
an exterior, visible light transmissive, gas-tight envelope enclosing said arc tube, said envelope having an ultraviolet sensitive phosphor disposed thereon and electrical conductors disposed therethrough and connected to said electrodes; and A vaporizable discharge medium disposed within said arc tube, said medium comprising material selected from the group consisting of copper halides, rhenium halides and silver halides.
2. The lamp of claim 1 in which said material selected is a copper halide and said copper halide is selected from the group consisting of copper iodide and copper bromide.
3. The lamp of claim 2 in which said copper halide is present in amounts from between about 0.05 mgms/cc and about 2 mgms/cc of arc tube volume.
4. The lamp of claim 1 in which said discharge medium further includes mercury.
5. The lamp of claim 4 in which the amount of mercury added is sufficient to produce a partial mercury vapor pressure of between about 0.1 atmosphere to about 10 atmospheres at operating temperatures between about 500°C
and about 900°C.
and about 900°C.
6. The lamp of claim 1 in which said phosphor is disposed on the inner wall of said outer envelope.
7. The lamp of claim 1 in which said outer envelope comprises ultraviolet transmissive material.
8. The lamp of claim 7 in which said phosphor is disposed on the outer wall of said outer envelope.
9. The lamp of claim 1 in which said discharge medium produces ultraviolet radiation at about 324.7 and 327.4 nanometers.
10. The lamp of claim 1 in which the region between said arc tube and said outer envelope is partially evacuated.
11. The lamp of claim 1 further including an inert starting gas within said arc tube.
12. The lamp of claim 1 in which the region between the said arc tube and said envelope is filled with an inert gas.
13. In a fluorescent/arc-discharge lamp, having an inner arc tube and an outer phosphor-coated envelope, a method of controlling the proportion of visible radiation produced by the arc and by the phosphor, comprising:
disposing a finite amount of a vaporizable discharge medium within said arc tube, said medium including copper halide; and adding an amount of mercury to said arc tube, whereby the amount of visible radiation from said arc is increased.
disposing a finite amount of a vaporizable discharge medium within said arc tube, said medium including copper halide; and adding an amount of mercury to said arc tube, whereby the amount of visible radiation from said arc is increased.
14. A fluorescent/arc-discharge lamp comprising:
a gas-tight, ultraviolet transmissive arc tube having electrodes disposed therein at either end thereof;
an exterior, visible light transmissive, gas-tight envelope enclosing said arc tube, said envelope having an ultraviolet sensitive phosphor disposed thereon and electrical conductors disposed therethrough and connected to said electrodes, said phosphor producing at least 20 percent of the visible light output from said lamp; and a vaporizable discharge medium disposed within said arc tube, said discharge medium comprising material selected from the group consisting of copper halides, rhenium halides and silver halides.
a gas-tight, ultraviolet transmissive arc tube having electrodes disposed therein at either end thereof;
an exterior, visible light transmissive, gas-tight envelope enclosing said arc tube, said envelope having an ultraviolet sensitive phosphor disposed thereon and electrical conductors disposed therethrough and connected to said electrodes, said phosphor producing at least 20 percent of the visible light output from said lamp; and a vaporizable discharge medium disposed within said arc tube, said discharge medium comprising material selected from the group consisting of copper halides, rhenium halides and silver halides.
15. A fluorescent/arc-discharge lamp comprising:
a gas-tight, ultraviolet transmissive arc tube having electrodes disposed therein at either end thereof;
an exterior, visible light transmissive gas-tight envelope enclosing said arc tube, said envelope having an ultraviolet sensitive phosphor disposed thereon and electrical conductors disposed therethrough and connected to said electrodes;
a vaporizable discharge medium disposed within said arc tube, said discharge medium comprising material selected from the group consisting of copper halides, rhenium halides and silver halides in sufficient quantity to ensure that said phosphor produces at least 20 percent of the light output from said lamp when said lamp is energized.
a gas-tight, ultraviolet transmissive arc tube having electrodes disposed therein at either end thereof;
an exterior, visible light transmissive gas-tight envelope enclosing said arc tube, said envelope having an ultraviolet sensitive phosphor disposed thereon and electrical conductors disposed therethrough and connected to said electrodes;
a vaporizable discharge medium disposed within said arc tube, said discharge medium comprising material selected from the group consisting of copper halides, rhenium halides and silver halides in sufficient quantity to ensure that said phosphor produces at least 20 percent of the light output from said lamp when said lamp is energized.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US28882281A | 1981-07-31 | 1981-07-31 | |
| US288,822 | 1981-07-31 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1205843A true CA1205843A (en) | 1986-06-10 |
Family
ID=23108786
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000407024A Expired CA1205843A (en) | 1981-07-31 | 1982-07-09 | Compact fluorescent lamp with copper-arc excitation |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1205843A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1187173A2 (en) * | 2000-09-08 | 2002-03-13 | Philips Corporate Intellectual Property GmbH | Low pressure gas discharge lamp with a copper-containing gas fill |
-
1982
- 1982-07-09 CA CA000407024A patent/CA1205843A/en not_active Expired
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1187173A2 (en) * | 2000-09-08 | 2002-03-13 | Philips Corporate Intellectual Property GmbH | Low pressure gas discharge lamp with a copper-containing gas fill |
| EP1187173A3 (en) * | 2000-09-08 | 2005-08-31 | Philips Intellectual Property & Standards GmbH | Low pressure gas discharge lamp with a copper-containing gas fill |
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