CA1246653A - Low wattage metal halide lamp - Google Patents
Low wattage metal halide lampInfo
- Publication number
- CA1246653A CA1246653A CA000483654A CA483654A CA1246653A CA 1246653 A CA1246653 A CA 1246653A CA 000483654 A CA000483654 A CA 000483654A CA 483654 A CA483654 A CA 483654A CA 1246653 A CA1246653 A CA 1246653A
- Authority
- CA
- Canada
- Prior art keywords
- discharge lamp
- metal halide
- halide discharge
- scandium
- arc tube
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J61/00—Gas-discharge or vapour-discharge lamps
- H01J61/02—Details
- H01J61/12—Selection of substances for gas fillings; Specified operating pressure or temperature
- H01J61/125—Selection of substances for gas fillings; Specified operating pressure or temperature having an halogenide as principal component
-
- 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
Abstract
ABSTRACT:
A low wattage metal halide discharge lamp includes a sealed outer envelope with a pair of electrical conductors passing therethrough and containing an arc tube having a pair of electrodes electrically connected to the pair of electrical conductors with a chemical fill within the arc tube including iodides of sodium and scandium of a molar ratio in the range of about 20:1 to 28:1.
A low wattage metal halide discharge lamp includes a sealed outer envelope with a pair of electrical conductors passing therethrough and containing an arc tube having a pair of electrodes electrically connected to the pair of electrical conductors with a chemical fill within the arc tube including iodides of sodium and scandium of a molar ratio in the range of about 20:1 to 28:1.
Description
6~
84-1-0~1 LOW ~ATTAGE METAL HALID LAMP
TECHNICAL Fl~LD:
This invention relate~ to low ~att,age ~etal halide la~p~
and more particularly to ~e configuration and chemical fill of low wattage metal halide lamps.
BACKGROUND ART:
Generally, metal halide disc~arge lamps av~ilable in todays market are of the intermediate or high wattage variety, i.e.. 175 to 1500 ~atts for example. Al~o, these h;gher wattage metal halide lamps have t~e higher efficacy which is directly related to efficiency and conveniently defined as the ratio of total lumen output to input power as expre~,sed in lumens per watt. Moreover, it is known that the efficacy of a lamp tend~ to decrease as the wattage decreases. Thus, it ha~
been generally presupposed that low wattage metal halide lamp6, wattages of 100-watts or le~s~ would be entirely unsatisfactory in ~o far as efficacy is concerned.
Another common practice in intermediate and rela~iYely ~igh wattage metal halide lamps is ~he provision of an iner~ fill gas in the outer envelope surrounding the arc tube.
Accordingly, it was believed that the inert fill ga~ would prevent oxidation of the metal parts located in the outer envelope and increases the breakdown voltage whereby arcing would be inhibited. However, it was ~ound that the undesired loss of heat due to on~ection currents made po66ible by the presence of the inert ga~ fiignificantly reduced the eficacy of the di~charge lamp.
Known attempts ~o reduce this undesired heat loss due to conve~tion current~ include the utilization of a gla~s cylinder surrounding the arc tube within ~he sealed ou~*r envelope.
However, structures which include ~ f ill gas in the outer envelope do have undesired convection currents. ~oreover~
these convection curren~ and ~he accompanying ~eat loss are ~, ~
pre~ent e~en though a gla~ cylinder like arrangement i6 employed.
Further, the 6mallest known dome~ti~ commerci~lized metal halide di~charge lamp i~ a Sylvania 175 watt l~mp for~ed for horizontal operation only and having a color tempera~ure of about 3000 X. Thi~ l~mp ha~ a pho~p~or-coated outer envelope which tran~for~ W radiation into visible red radi~tion thereby creating a relatively warm color appearance. However, the lamp undesirably re~uire~ a relatively large and cu~ber~ome luminaire for adequate light di~tribution control, in addition, ha~ ~e disadvantage of being operable in a horizontal po~ition only.
OBJ~CTS AND 5UMMARY OF THE INVENT ON:
An object of the present invention i~ to o~ercome the dif f icultie~ of the prior art. Another object of the invention i~ to provicle an improved me~al halide discharge lamp having relatively low wattage and reduced heat lo~es due to convection current6. Still another object of the invention is to provide a low wat~age hig~ efficiency metal halide di~charge lamp of ~mall ~ize ana having a color temp~rature of abou~
3000K. A further object of the invention i~ to provide a chemical fill for a low wat~a~e relatively high efficacy metal halide di~charge lamp.
The~e and other object~, advantage6 ~nd capabilitie~ are achieved in one a~pect of the invention by a low wattage metal halide di~charge lamp havi~g an outer glass envelope with a pair of electrical conductor~ ~ealed into and pa~sing therethrough, an arc tu~e dispo~ed wit~i~ the envelope and t~e arc tube having a pair of ~paced electrode~ with each of the elec~rode~ electrically connectea to one of the pair of electrical conductors and a chemical fill within the arc tube including ~odiu~ and ~candium iodide~ of a molar ratio in ~he range of about 20:1 to 28:1.
~".
~, ~2~6~3 ~4-1-081 BRIEF DESC_IPTION OF THE DRAWINGS:
FIG. 1 i6 a cro~-6ectional vie~ of a low wattage metal halide di~charge lamp ~f the invention;
PIG. 2 is chromaticity coordinate chart for molar ratio~ of ~odium iodide to ~candium iodide;
~ IG. ~ is a chart illu6trating the color temperature (Tc) and color rendering index ~CRI) for molor ratio~ of ~odium iodide and 6candium iodide: and ~ IG. 4 is a comparison chart illustrating the lumens per watt of low wattage metal ~alide discharge lamp~ at variou6 ~odium to ~candium iodide molar ra~io~.
BEST I~ODE FOR CARRYING OUT THE INVENTION:
~ or a better understanding of the pre~ent invention.
together with other and furt~er o~jects, adva~tages and capabilitie~ thereof, reference is made to the followin~
disclo&ure and appended claims in conjunction with the accompanying drawings.
Referring to FIG. 1 of the drawings, a low wattage metal halide a c discharge lamp 5 importantly include an evacuated outer envelope 7. Thi~ evacuated outer envelope 7 i~
her~e~ically æealed to a gla6s stem member 9 having an external base member 11 affixed thereto. A pair of elec~rical conductors 13 and 15 ar~ sealed into and pas~ through the ~tem membe~ 9 and provide acces~ for e~ergization of the di~charge lamp 5 by an external ~ource (no~ 6hown).
~ i~hin the vacuum of the evacuated outer envelope 7, a support membe~ 17 i~ affixed to o~e of ~be ~lectrical conductors 13 and extend~ ~ub6tantially parallel to the longitudinal axi~ of t~e lamp 5 and forms a circular configuration 19 near the upper portion of the enYelope 7.
Thi~ circular configuration 19 in conjunction with the upper portion of the envelope 7 tend6 to maintain ths 6upport member 17 in proper alignment and resi~tant ~o de~ormation cau6ed by external sho~k.
..~
8q-1-081 ~ irfit ~trap ~ember 21 is welded to the ~upport member 17 and e~tends therefrom in a direction normal to the longitudinal axi~ and the direction of the ~upport member 17. A domed guart2 ~leeve or ~emperature equalizing mean~ 23 ha~ a pair of sppo~i~ely di~posed notche6 Z5 and 27 on the and thereof 28 opposite to the dome portion. The~e notche6 25 and 27 are formed to ~lip over the first 6trap member 21 which 6erve~ to ~upport the domed quartz ~leeve 23. Also, a sub~ta~tially circular ~haped ~trap 29 ~urround~ the domed quartz sleeve 23 near the domed portion thereof and i~ attached to the ~upport me~bar 17.
Within the temperature equalizing ~eans or domed quar~z sleeve 23 i~ an arc tube 31 having a chemical fill including elemental ~candium and mercury, ~odium~ 6candium and ce6ium iodides and an inert gas. The arc tube 31 ha~ a pinch &e~l at opposite end6 t~ereof, 33 and 35 re~pectively. Metal foil members 37 and 39 are ~ealed into the press ~eals 33 and 35 and elec~rical conductor& 41 and 93 are attac~ed to the foil member~ 37 and 39 and extend outwardly from the pre~6 ~eal~ 33 and 35. A flexi~le support member 45 i6 affixed to one of the electrical conductor6 41 and to the ~upport member 17. Al~o, lead 47 is afixed to the other electrical conductor 43 which pa~se~ through the domed portion of t~e domed quart2 sleeve 23. ~oreov~r, a flexible spring-lika member 49 connects the lead 47 to the other one 15 of the pair of electrical conduc~ors 13 and 15. A pair of getter~ 51 and 53 are affixed to the electrical csnductor6 13 and 15 and ~ar~e to provide and maintai~ the vacuum within the e~acuated outer enYelope 7 and the domed quartz ~leeve 23.
Referring to the arc tube ~1, a preferred configura~ion, suitable or u~e in a metal halide lamp of a si2e in the ra~ge of about 40 to 150 watt~ for example, would have an inner diameter of abou~ lOmm and an arc leng~h ~etween the electrode~
Si3 84-1-o~l 41 and 43 of a~out 14~m. Also. it may be noted tbat ~ach of the end~ of the arc tube 31 immediately adjacent and including the pres~ seal~ 33 and 35 i6 coated wit~ a ~hite zirconium oxide paint in order to provide a wall temperature of i~crea~ed unifor~ity. Moreover, it ha~ been found that a wall loading in the range of about 14 to 17 watt6~m2 i~ preferable and now attainable in ~etal ~alide la~ps of a 6ize in the range o ab~ut 40 to 150-watt~, and of t~e abo~e-mentionsd configuration.
Referring to the chemical fill o-f the above-mentio~ed dixcharge lamp configuration, the comparison graph of FIG. 2 illu~trate~ ~ariou6 ratio~ of ~odium and ~candium-iodides as plo~ed on chromaticity coordinate~ (x and y) of a standard chro~aticity chart. As can readily be seen on the graph, the molar ratio of sodium to scandium iodide which most closely approaches the hig~ly desirable black body (BB) cur~e representatiYe of the output of an incandescent lamp i6 a molar ratio in the range of about 20:1 to 28:1. More specifically, a sodium to ~candium iodide molars ratio of about 24:1 appear~ to be a highly desirable fill condition for metal halide di~charge lamps. Moreover, i~ is to be noted that ~he above-mentioned highly desirable sodium to scandium iodide molar ratios a~e biased toward the red side ~below the BB curve~ which i~
preferable in terms of general illumination application~.
Al60, the color temperatures ~Tc) and general color rendering index (CRI) for the above-mentioned lamps having various molar ratios is illustrated in FIG. 3. As can be &een, the previou~ly-mentioned de~irable molar ranse of about 20:1 to 28 :1 c~f ~odium to 6candium iodide6 provide6 a desired color temperature of about 3000K within a range of not ~ore or les~
t~an about 200K. ~oreover, the 60dium to ~candium iodide molar ratio of about 24:~ appears to very clo~ely approac~ the de~ired 3000K color temperature.
84~ 81 Fur~her, t~e compari~on graph of FIG. 3 al60 illus~ra~e6 ~he cons~ant color xendering index ~C~I) at variou~ molar ra~ios of 60dium to 6candium iodide. Again, it can be seen that a molar ratio of about 24:1 appro~iches a hi~hly de~irable value of about 65.0 on t~e CRI index w.ith the ran~e of molar ratios of about 20:1 to 28~1 not varyil~g rom t~e preferred value of 65.0 by not ~ore or le~6 than about 2.0 indice~.
~ lso, the lamp ~fficiency a~ the above-mentionecl ~arying molar ratio~ of ~odium to scandium iod-;2es i~ illustrated in FIG. ~. Herein it can be ~een tha~ a sodium to scandium iodide molar ratio of about 24~1 provide~ a desirable efficiency of about 100 lumen~ per watt (LP~). Moreover, thi6 de~irable 100 LPW capability remain~ sub~tantially co~6tant over a sodium to ~candium iodide molar ratio in the range of about 20:1 to 2~:1.
Further, tests were run to determine an optimum dosage of sodium to scandium iodide at a molar ratio of about 24:1.
Employing a lamp having an arc tube volume of about 1 cm~ and varying to ~alt dosage from about 8 to 20 mg, it was found ~hat a dosage of about 12 mg/cm3 at the preferred molar ratio of about 24~1 yielded the highest lumen~ per watt ~nd color re~dering index (CRI). At do~ayes of a weight less than about 12 ~g, it wa~ found that the desired color rendering index (CRI) could not be ~ustained while dosage~ greater than abou~
12 mg resulted in poor lumen mainte~ance and a 6hortened lamp life. ~oreover, it was found that a dosage of about 12 mg~cm3 wa~ m~st appropriate for lamp~ in the range of about 40 to 150 watts.
Additionally, it ha6 been found tnat the incorpora~ion o$
cesium iodide into ~he lamp dosage enhance~ ~he starting time of the di~charge lamp. Upon the inclufiion of ce~ium iodide in ~e range of about 0.3 to 1.0 mg i~ the above-men~ioned lamp6, it was found that the lamp ~tar~ing could be reduced from an average of about one to one and one-half (1~ 2) minute~
~,,~
~4-1-081 witbout the ce~ium iodide to virtual instanta~eou6 ~tarting (less than 1-6ec) w~en a do~age of about 0.5 ~g was employed.
Lesser amounts of cesiu~ iodide provide much 6~aller improvements in starting time while greater amount~ tended ~o degrade lamp e~fi~iency and warm color ~haracteristics. Thus 7 ~he preferred dosage for a metal halide dischdrge lamp ha~i~g a volume of about 1 cm3 and a wattage in the range of about 4~
'co 150 watt6 includes about 12mg of sodium, scandium and cesium iodides in the molar ratio of about 24 :1 : O. 6.
~ n addition to the a~ove-mentioned components, it has been determined that a weight dosage of about 100 micrograms/cm3 of elemental scandium, elemental mercury in accordance with the formula:
N (Hg) (mg~cm3~ = 7.7 D 1~7 where D = arc tube diameter in millimeter~
and argon gas at a pressure of abou~ 100 torr are most appropriate ~o the above men~ioned metal halide lamps of about 40 to 150 watts. Thus, a di~charge lamp of enhanced color temperature, starting ~apability, extended life and efficiency i~ at~ainable i~ wattage~ less than preYiously known.
~ hile there has been shown and described what is at presen~
considered the preferred embodiments of this invention, it will be obvious to those skillea in ~he art t~at variou6 change6 and modifications may b~ made therein without departin~ from the invention as defined by the appended claims.
.. . .
84-1-0~1 LOW ~ATTAGE METAL HALID LAMP
TECHNICAL Fl~LD:
This invention relate~ to low ~att,age ~etal halide la~p~
and more particularly to ~e configuration and chemical fill of low wattage metal halide lamps.
BACKGROUND ART:
Generally, metal halide disc~arge lamps av~ilable in todays market are of the intermediate or high wattage variety, i.e.. 175 to 1500 ~atts for example. Al~o, these h;gher wattage metal halide lamps have t~e higher efficacy which is directly related to efficiency and conveniently defined as the ratio of total lumen output to input power as expre~,sed in lumens per watt. Moreover, it is known that the efficacy of a lamp tend~ to decrease as the wattage decreases. Thus, it ha~
been generally presupposed that low wattage metal halide lamp6, wattages of 100-watts or le~s~ would be entirely unsatisfactory in ~o far as efficacy is concerned.
Another common practice in intermediate and rela~iYely ~igh wattage metal halide lamps is ~he provision of an iner~ fill gas in the outer envelope surrounding the arc tube.
Accordingly, it was believed that the inert fill ga~ would prevent oxidation of the metal parts located in the outer envelope and increases the breakdown voltage whereby arcing would be inhibited. However, it was ~ound that the undesired loss of heat due to on~ection currents made po66ible by the presence of the inert ga~ fiignificantly reduced the eficacy of the di~charge lamp.
Known attempts ~o reduce this undesired heat loss due to conve~tion current~ include the utilization of a gla~s cylinder surrounding the arc tube within ~he sealed ou~*r envelope.
However, structures which include ~ f ill gas in the outer envelope do have undesired convection currents. ~oreover~
these convection curren~ and ~he accompanying ~eat loss are ~, ~
pre~ent e~en though a gla~ cylinder like arrangement i6 employed.
Further, the 6mallest known dome~ti~ commerci~lized metal halide di~charge lamp i~ a Sylvania 175 watt l~mp for~ed for horizontal operation only and having a color tempera~ure of about 3000 X. Thi~ l~mp ha~ a pho~p~or-coated outer envelope which tran~for~ W radiation into visible red radi~tion thereby creating a relatively warm color appearance. However, the lamp undesirably re~uire~ a relatively large and cu~ber~ome luminaire for adequate light di~tribution control, in addition, ha~ ~e disadvantage of being operable in a horizontal po~ition only.
OBJ~CTS AND 5UMMARY OF THE INVENT ON:
An object of the present invention i~ to o~ercome the dif f icultie~ of the prior art. Another object of the invention i~ to provicle an improved me~al halide discharge lamp having relatively low wattage and reduced heat lo~es due to convection current6. Still another object of the invention is to provide a low wat~age hig~ efficiency metal halide di~charge lamp of ~mall ~ize ana having a color temp~rature of abou~
3000K. A further object of the invention i~ to provide a chemical fill for a low wat~a~e relatively high efficacy metal halide di~charge lamp.
The~e and other object~, advantage6 ~nd capabilitie~ are achieved in one a~pect of the invention by a low wattage metal halide di~charge lamp havi~g an outer glass envelope with a pair of electrical conductor~ ~ealed into and pa~sing therethrough, an arc tu~e dispo~ed wit~i~ the envelope and t~e arc tube having a pair of ~paced electrode~ with each of the elec~rode~ electrically connectea to one of the pair of electrical conductors and a chemical fill within the arc tube including ~odiu~ and ~candium iodide~ of a molar ratio in ~he range of about 20:1 to 28:1.
~".
~, ~2~6~3 ~4-1-081 BRIEF DESC_IPTION OF THE DRAWINGS:
FIG. 1 i6 a cro~-6ectional vie~ of a low wattage metal halide di~charge lamp ~f the invention;
PIG. 2 is chromaticity coordinate chart for molar ratio~ of ~odium iodide to ~candium iodide;
~ IG. ~ is a chart illu6trating the color temperature (Tc) and color rendering index ~CRI) for molor ratio~ of ~odium iodide and 6candium iodide: and ~ IG. 4 is a comparison chart illustrating the lumens per watt of low wattage metal ~alide discharge lamp~ at variou6 ~odium to ~candium iodide molar ra~io~.
BEST I~ODE FOR CARRYING OUT THE INVENTION:
~ or a better understanding of the pre~ent invention.
together with other and furt~er o~jects, adva~tages and capabilitie~ thereof, reference is made to the followin~
disclo&ure and appended claims in conjunction with the accompanying drawings.
Referring to FIG. 1 of the drawings, a low wattage metal halide a c discharge lamp 5 importantly include an evacuated outer envelope 7. Thi~ evacuated outer envelope 7 i~
her~e~ically æealed to a gla6s stem member 9 having an external base member 11 affixed thereto. A pair of elec~rical conductors 13 and 15 ar~ sealed into and pas~ through the ~tem membe~ 9 and provide acces~ for e~ergization of the di~charge lamp 5 by an external ~ource (no~ 6hown).
~ i~hin the vacuum of the evacuated outer envelope 7, a support membe~ 17 i~ affixed to o~e of ~be ~lectrical conductors 13 and extend~ ~ub6tantially parallel to the longitudinal axi~ of t~e lamp 5 and forms a circular configuration 19 near the upper portion of the enYelope 7.
Thi~ circular configuration 19 in conjunction with the upper portion of the envelope 7 tend6 to maintain ths 6upport member 17 in proper alignment and resi~tant ~o de~ormation cau6ed by external sho~k.
..~
8q-1-081 ~ irfit ~trap ~ember 21 is welded to the ~upport member 17 and e~tends therefrom in a direction normal to the longitudinal axi~ and the direction of the ~upport member 17. A domed guart2 ~leeve or ~emperature equalizing mean~ 23 ha~ a pair of sppo~i~ely di~posed notche6 Z5 and 27 on the and thereof 28 opposite to the dome portion. The~e notche6 25 and 27 are formed to ~lip over the first 6trap member 21 which 6erve~ to ~upport the domed quartz ~leeve 23. Also, a sub~ta~tially circular ~haped ~trap 29 ~urround~ the domed quartz sleeve 23 near the domed portion thereof and i~ attached to the ~upport me~bar 17.
Within the temperature equalizing ~eans or domed quar~z sleeve 23 i~ an arc tube 31 having a chemical fill including elemental ~candium and mercury, ~odium~ 6candium and ce6ium iodides and an inert gas. The arc tube 31 ha~ a pinch &e~l at opposite end6 t~ereof, 33 and 35 re~pectively. Metal foil members 37 and 39 are ~ealed into the press ~eals 33 and 35 and elec~rical conductor& 41 and 93 are attac~ed to the foil member~ 37 and 39 and extend outwardly from the pre~6 ~eal~ 33 and 35. A flexi~le support member 45 i6 affixed to one of the electrical conductor6 41 and to the ~upport member 17. Al~o, lead 47 is afixed to the other electrical conductor 43 which pa~se~ through the domed portion of t~e domed quart2 sleeve 23. ~oreov~r, a flexible spring-lika member 49 connects the lead 47 to the other one 15 of the pair of electrical conduc~ors 13 and 15. A pair of getter~ 51 and 53 are affixed to the electrical csnductor6 13 and 15 and ~ar~e to provide and maintai~ the vacuum within the e~acuated outer enYelope 7 and the domed quartz ~leeve 23.
Referring to the arc tube ~1, a preferred configura~ion, suitable or u~e in a metal halide lamp of a si2e in the ra~ge of about 40 to 150 watt~ for example, would have an inner diameter of abou~ lOmm and an arc leng~h ~etween the electrode~
Si3 84-1-o~l 41 and 43 of a~out 14~m. Also. it may be noted tbat ~ach of the end~ of the arc tube 31 immediately adjacent and including the pres~ seal~ 33 and 35 i6 coated wit~ a ~hite zirconium oxide paint in order to provide a wall temperature of i~crea~ed unifor~ity. Moreover, it ha~ been found that a wall loading in the range of about 14 to 17 watt6~m2 i~ preferable and now attainable in ~etal ~alide la~ps of a 6ize in the range o ab~ut 40 to 150-watt~, and of t~e abo~e-mentionsd configuration.
Referring to the chemical fill o-f the above-mentio~ed dixcharge lamp configuration, the comparison graph of FIG. 2 illu~trate~ ~ariou6 ratio~ of ~odium and ~candium-iodides as plo~ed on chromaticity coordinate~ (x and y) of a standard chro~aticity chart. As can readily be seen on the graph, the molar ratio of sodium to scandium iodide which most closely approaches the hig~ly desirable black body (BB) cur~e representatiYe of the output of an incandescent lamp i6 a molar ratio in the range of about 20:1 to 28:1. More specifically, a sodium to ~candium iodide molars ratio of about 24:1 appear~ to be a highly desirable fill condition for metal halide di~charge lamps. Moreover, i~ is to be noted that ~he above-mentioned highly desirable sodium to scandium iodide molar ratios a~e biased toward the red side ~below the BB curve~ which i~
preferable in terms of general illumination application~.
Al60, the color temperatures ~Tc) and general color rendering index (CRI) for the above-mentioned lamps having various molar ratios is illustrated in FIG. 3. As can be &een, the previou~ly-mentioned de~irable molar ranse of about 20:1 to 28 :1 c~f ~odium to 6candium iodide6 provide6 a desired color temperature of about 3000K within a range of not ~ore or les~
t~an about 200K. ~oreover, the 60dium to ~candium iodide molar ratio of about 24:~ appears to very clo~ely approac~ the de~ired 3000K color temperature.
84~ 81 Fur~her, t~e compari~on graph of FIG. 3 al60 illus~ra~e6 ~he cons~ant color xendering index ~C~I) at variou~ molar ra~ios of 60dium to 6candium iodide. Again, it can be seen that a molar ratio of about 24:1 appro~iches a hi~hly de~irable value of about 65.0 on t~e CRI index w.ith the ran~e of molar ratios of about 20:1 to 28~1 not varyil~g rom t~e preferred value of 65.0 by not ~ore or le~6 than about 2.0 indice~.
~ lso, the lamp ~fficiency a~ the above-mentionecl ~arying molar ratio~ of ~odium to scandium iod-;2es i~ illustrated in FIG. ~. Herein it can be ~een tha~ a sodium to scandium iodide molar ratio of about 24~1 provide~ a desirable efficiency of about 100 lumen~ per watt (LP~). Moreover, thi6 de~irable 100 LPW capability remain~ sub~tantially co~6tant over a sodium to ~candium iodide molar ratio in the range of about 20:1 to 2~:1.
Further, tests were run to determine an optimum dosage of sodium to scandium iodide at a molar ratio of about 24:1.
Employing a lamp having an arc tube volume of about 1 cm~ and varying to ~alt dosage from about 8 to 20 mg, it was found ~hat a dosage of about 12 mg/cm3 at the preferred molar ratio of about 24~1 yielded the highest lumen~ per watt ~nd color re~dering index (CRI). At do~ayes of a weight less than about 12 ~g, it wa~ found that the desired color rendering index (CRI) could not be ~ustained while dosage~ greater than abou~
12 mg resulted in poor lumen mainte~ance and a 6hortened lamp life. ~oreover, it was found that a dosage of about 12 mg~cm3 wa~ m~st appropriate for lamp~ in the range of about 40 to 150 watts.
Additionally, it ha6 been found tnat the incorpora~ion o$
cesium iodide into ~he lamp dosage enhance~ ~he starting time of the di~charge lamp. Upon the inclufiion of ce~ium iodide in ~e range of about 0.3 to 1.0 mg i~ the above-men~ioned lamp6, it was found that the lamp ~tar~ing could be reduced from an average of about one to one and one-half (1~ 2) minute~
~,,~
~4-1-081 witbout the ce~ium iodide to virtual instanta~eou6 ~tarting (less than 1-6ec) w~en a do~age of about 0.5 ~g was employed.
Lesser amounts of cesiu~ iodide provide much 6~aller improvements in starting time while greater amount~ tended ~o degrade lamp e~fi~iency and warm color ~haracteristics. Thus 7 ~he preferred dosage for a metal halide dischdrge lamp ha~i~g a volume of about 1 cm3 and a wattage in the range of about 4~
'co 150 watt6 includes about 12mg of sodium, scandium and cesium iodides in the molar ratio of about 24 :1 : O. 6.
~ n addition to the a~ove-mentioned components, it has been determined that a weight dosage of about 100 micrograms/cm3 of elemental scandium, elemental mercury in accordance with the formula:
N (Hg) (mg~cm3~ = 7.7 D 1~7 where D = arc tube diameter in millimeter~
and argon gas at a pressure of abou~ 100 torr are most appropriate ~o the above men~ioned metal halide lamps of about 40 to 150 watts. Thus, a di~charge lamp of enhanced color temperature, starting ~apability, extended life and efficiency i~ at~ainable i~ wattage~ less than preYiously known.
~ hile there has been shown and described what is at presen~
considered the preferred embodiments of this invention, it will be obvious to those skillea in ~he art t~at variou6 change6 and modifications may b~ made therein without departin~ from the invention as defined by the appended claims.
.. . .
Claims (22)
1. A low wattage metal halide discharge lamp comprising:
an outer sealed glass envelope;
a pair of electrical conductors sealed into and passing through said glass envelope;
an arc tube disposed within said outer glass envelope, said arc tube having a pair of spaced electrodes therein with each electrode electrically connected to one of said pair of electrical conductors; and a chemical fill disposed within said arc tube, said fill consisting essentially of sodium iodide and scandium iodide in a molar ratio in the range of about 20:1 to 28:1, elemental mercury, scandium, and an inert gas.
an outer sealed glass envelope;
a pair of electrical conductors sealed into and passing through said glass envelope;
an arc tube disposed within said outer glass envelope, said arc tube having a pair of spaced electrodes therein with each electrode electrically connected to one of said pair of electrical conductors; and a chemical fill disposed within said arc tube, said fill consisting essentially of sodium iodide and scandium iodide in a molar ratio in the range of about 20:1 to 28:1, elemental mercury, scandium, and an inert gas.
2. The low-wattage metal halide discharge lamp of Claim 1 wherein said chemical fill further includes cesium iodide.
3. The low wattage metal halide discharge lamp of Claim 2 wherein said sodium iodide, scandium, iodide, and cesium iodide are in a molar ratio of about 24:1 : 0.6.
4. The low wattage metal halide discharge lamp of Claim 1 wherein said discharge lamp is of a size in the range of about 40 to 150 watts.
5. The low wattage metal halide discharge lamp of claim 1 wherein said discharge lamp includes an evacuated sealed glass envelope and a temperature equalizing means within said envelope and surrounding said arc tube.
6. The low wattage metal halide discharge lamp of Claim 2 wherein said cesium iodide is present in a weight dosage of about 0.5 mg/cm3.
7. The low wattage metal halide discharge lamp of Claim 1 wherein said chemical fill further includes cesium iodide, and said sodium iodide, scandium iodide, and cesium iodide are of a weight dosage of about 12 mg/cm3.
8. The low wattage metal halide discharge lamp of Claim 1 wherein said elemental scandium is present in a weight dosage in the range of about 90 to 110 micrograms/cm3.
9. The low wattage metal halide discharge lamp of Claim 1 wherein said inert gas is at a pressure of about 100 torr.
10. The low wattage metal halide discharge lamp of Claim 1 wherein said elemental mercury is present at a weight dosage in accordance with the formula:
N (Hg) (mg/cm3) = 7.7 D1/7 wherein: D = arc tube inner diameter in millimeters.
N (Hg) (mg/cm3) = 7.7 D1/7 wherein: D = arc tube inner diameter in millimeters.
11. The low wattage metal halide discharge lamp of Claim 1 wherein said discharge lamp has a color temperature of about 3000°K within a range of not more nor less than about 200°K.
12. The low wattage metal halide discharge lamp of Claim 1 wherein said lamp has a color rendering index (CRI) of about 65 within a range of not more nor less than about 2.0 indices.
13. The low wattage metal halide discharge lamp of Claim 1 wherein said arc tube has a wall loading in the range of about 14 to 17 watts/cm2.
14. A metal halide discharge lamp in the range of about 40 to 150 watts comprising:
an evacuated outer envelope;
a pair of electrical conductors sealed into and passing through said outer envelope;
an arc tube disposed within said outer envelope and having a pair of spaced electrodes with each of said electrodes electrically connected to one of said pair of electrical conductors;
a domed quartz sleeve telescoped over said arc tube within said outer envelope; and a chemical fill within said arc tube, said fill consisting essentially of elemental scandium, elemental mercury, an inert gas, and iodides of sodium, scandium, and cesium with said sodium and scandium iodides being of a molar ratio in the range of about 20:1 to 28:1.
an evacuated outer envelope;
a pair of electrical conductors sealed into and passing through said outer envelope;
an arc tube disposed within said outer envelope and having a pair of spaced electrodes with each of said electrodes electrically connected to one of said pair of electrical conductors;
a domed quartz sleeve telescoped over said arc tube within said outer envelope; and a chemical fill within said arc tube, said fill consisting essentially of elemental scandium, elemental mercury, an inert gas, and iodides of sodium, scandium, and cesium with said sodium and scandium iodides being of a molar ratio in the range of about 20:1 to 28:1.
15. The metal halide discharge lamp of Claim 14 wherein said sodium, scandium and cesium iodides are of a molar ratio of about 24:1 : 0.6.
16. The metal halide discharge lamp of Claim 14 wherein said cesium iodide is of a dosage of about 0.5 mg/cm3.
17. The metal halide discharge lamp of Claim 14 wherein said iodides of sodium, scandium and cesium are of a dosage of about 12 mg/cm3.
18. The metal halide discharge lamp of Claim 14 wherein said elemental scandium is of a dosage in the range of about 90 to 110 micrograms/cm3.
19. The metal halide discharge lamp of Claim 14 wherein said inert gas is argon at a pressure of about 100 torr.
20. The low wattage metal halide discharge lamp of Claim 14 wherein said elemental mercury is present at a weight dosage in accordance with the formula:
N (Hg) (mg/cm3) = 7.7 D1/7 wherein: D = arc tube inner diameter in millimeters.
N (Hg) (mg/cm3) = 7.7 D1/7 wherein: D = arc tube inner diameter in millimeters.
21. The metal halide discharge lamp of Claim 14 wherein said lamp has a color temperature of about 3000°K within a range of not more than or less than about 200°K.
22. The metal halide discharge lamp of Claim 14 wherein said arc tube has a wall loading in the range of about 14 to 17 watts/cm2.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US64200984A | 1984-08-20 | 1984-08-20 | |
| US642,009 | 1984-08-20 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1246653A true CA1246653A (en) | 1988-12-13 |
Family
ID=24574787
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000483654A Expired CA1246653A (en) | 1984-08-20 | 1985-06-11 | Low wattage metal halide lamp |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0173235B1 (en) |
| JP (1) | JPS6164060A (en) |
| CA (1) | CA1246653A (en) |
| DE (1) | DE3583314D1 (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA1324633C (en) * | 1988-09-12 | 1993-11-23 | Zeya K. Krasko | Metal halide discharge lamp with improved color rendering properties |
| JP2510274Y2 (en) * | 1990-01-25 | 1996-09-11 | カルソニック株式会社 | Piping joints for automobile air conditioners |
| DE4132530A1 (en) * | 1991-09-30 | 1993-04-01 | Patent Treuhand Ges Fuer Elektrische Gluehlampen Mbh | HIGH PRESSURE DISCHARGE LAMP WITH LOW POWER |
| CA2119336A1 (en) * | 1993-03-19 | 1994-09-20 | Edward H. Nortrup | Metal halide arc lamp having glass containment shroud |
| DE4317252C1 (en) * | 1993-05-24 | 1994-05-05 | Blv Licht & Vakuumtechnik | Gas discharge lamp - has breakage protection provided by grid incorporated in transparent envelope enclosing discharge vessel |
| US6376988B1 (en) | 1998-08-28 | 2002-04-23 | Matsushita Electric Industrial Co., Ltd. | Discharge lamp for automobile headlight and the automobile headlight |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL113900C (en) * | 1958-05-06 | |||
| JPS5725946B2 (en) * | 1973-07-19 | 1982-06-01 | ||
| JPS57197740A (en) * | 1982-05-14 | 1982-12-04 | Hitachi Ltd | Metal halide lamp |
-
1985
- 1985-06-11 CA CA000483654A patent/CA1246653A/en not_active Expired
- 1985-08-19 JP JP18061585A patent/JPS6164060A/en active Pending
- 1985-08-20 DE DE8585110460T patent/DE3583314D1/en not_active Expired - Fee Related
- 1985-08-20 EP EP19850110460 patent/EP0173235B1/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| EP0173235B1 (en) | 1991-06-26 |
| DE3583314D1 (en) | 1991-08-01 |
| JPS6164060A (en) | 1986-04-02 |
| EP0173235A3 (en) | 1988-10-19 |
| EP0173235A2 (en) | 1986-03-05 |
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| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |