CA1037097A - Discharge lamps containing an inert gas and a metal halide - Google Patents
Discharge lamps containing an inert gas and a metal halideInfo
- Publication number
- CA1037097A CA1037097A CA228,708A CA228708A CA1037097A CA 1037097 A CA1037097 A CA 1037097A CA 228708 A CA228708 A CA 228708A CA 1037097 A CA1037097 A CA 1037097A
- Authority
- CA
- Canada
- Prior art keywords
- lamp
- metal halide
- discharge
- inert gas
- discharge lamp
- 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
-
- 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
Landscapes
- Discharge Lamp (AREA)
- Discharge Lamps And Accessories Thereof (AREA)
Abstract
ABSTRACT
A discharge lamp has an inert gas such as xenon as the primary filling gas together with a metal halide to modify the discharge, for example the iodides of thallium, sodium, gallium or indium. The lamp is operated at a current density in excess of 16 mA/sq.mm and typically above 80 mA/sq.mm, the inert gas pressure being in excess of 300 terr. The lamps thereby possess a positive differential resistance.
A discharge lamp has an inert gas such as xenon as the primary filling gas together with a metal halide to modify the discharge, for example the iodides of thallium, sodium, gallium or indium. The lamp is operated at a current density in excess of 16 mA/sq.mm and typically above 80 mA/sq.mm, the inert gas pressure being in excess of 300 terr. The lamps thereby possess a positive differential resistance.
Description
~C~37~7 The present invention rel~tes tu dlschar~e lam~s containing ~n iner~ gas such as x~non as the prima~y fillir.g gas together with a metal halide to modify tne nature of the ~-discharge.
In an article in l'Applied Optics" Vo1~ 10, ~o. 11, ~ovember 19711 pp. 2517 - 2520, C.~. Gallo has described the production of "Continuous emission spectra from long linear ~
xenon discharge lamps with metallic halide additives". ~ ~-Gallo used thallium iodide or tin iodide as the additi~e, which was present in excess as a solid mass filling the volume behind the electrodes. ~he cold-filled xenon pressure was between 25 torr and ~ 2 atm. ~nd the optimum value was found to be around 80 torr. l'he lamps had a negative dif~erential resistivit~, that is to say, the arc ~oltage dropped as the current increased, and in conseque~ce the current used by Gallo was limited to values below 140 mA at ~bout 4.5 K~. ~he lamps described by Gallo had quartz envelopes with an internal diameter of 3.5 mm, thus the current density was below 14.5 mA/sq.mm. The lamps operated in a power ran~e between a few watts per linear cm and`about 30 watts per linear cm.
- The Applicant has now found that b~ operating dis- ;
charge lamps of the kind described by Gallo at higher current densities in excess of 16 mA/sq.mm, and generally in the range of 20 mA/sq.mm to 140 mA/sq.mm or more, one obtains a .
positive differential resistivity with the arc voltage i~creasin~ with current, which allows the stabilising ballast ~-: . ~ ::
, .. . .. ..
.
~03710~7 normally used to be much reduced in size or even elimin-ated altogether s~nce the lamp becomes self-stabilising.
For optimum operation in this re~ion it is found that cold-fill xenon pressures o~ 300 to 500 torr and preferably 400 to 500 torr are desirable, in contrast to the preferred pressure of about 80 torr in Gallo's lamps. It is then possible to obtain luminous efficiencies in excess of 50 lumens/watt and under favourable conditions of 8G lumens/watt and even as high as 125 lumens/watt.
As alternatives to thallium iodide the Applicant has also used sodium iodide and gallium iodide, in each case in excess. With arc tubes of about 8 mm diameter, that is to say, somewhat lar~er than those of Gallo, and~a xènon cold-fill pressure of around L~50 torr in each case, the transition 'l5 from a negative to a positive differential reslstivity took place at about 1.3A for ~allium, 2.5A for thallium, and 4~5A
for sodium, corresponding to current densities of about 25, 50 and 90 mA/sq.mm respectively. ~he positive slope i~
steepest for ~allium and least steep for sodium. In all cases the lumi~ous efficiency rises as the current is increased on the positive side of the curve. The arc voltage for gallium iB in excess of 340 volts, and that for thallium above 145 volts, while for sodium it is above 108 volts.
In the case of lamps containing an excess of ~odium iodide, with a guart3 tube of bore diameter from 6 to 10 m~ ;
it has been found that the optimum xenon pressure lies in . .
~3~
.
'.
~ al37(3g~
the range 400 to 500 torr and is preferably about 450 torr.
With a power input of 40 W~linear cm a luminous efficiency of 125 lumens~watt has been achieved, while at a lower loading - of 25 W/linear cm the efficiency is 80 lumens/watt. The colour of the light is that of low pressure sodium, with a chromaticity of x = 0.562, y = 0.410. To provide arc ignition in the xenon fill gas it is necessary to use an ignition voltage of some 20 Kv. It is possible to operate such a lamp on the positive part of its resistivity characteristic with a lamp ballast which carries a differential of only l volt between the lamp voltage and the supply voltage.
In one specific example, the arc tubè is formed of . .
fused silica, had a bore of 8 mm diameter, and provided an ` ~ `
arc length of l9 cm. 40 Mg of sodium iodide is contained in the tube, which is filled with xenon at 450 torr. Above a current from a minimum of around 108 volts and using minimal ~` -..
impedance in series with the lamp, an 8~ rise in voltage will result in a 22% rise in wattage. To keep lamp watts within : . :.
acceptable limits it may be desirable to use a small ballast choke but this need be no more than a quarter of the weight and size o the normal choke used with a mercury-filled discharge lamp.
According to one broad àspect, the invention relates to a method of operating a discharge lamp which comprises providing a lamp having an inert gas as the primary filling gas at a cold- -fill pressure in the range 300 to 500 torr together with a metal halide to modify the discharge, and passing a current through ~
the lamp at a currenk density sufficientiy greater than 16 mA~ ``
sg.mm for the lamp to operate in a region of positive differential resistivity.
' . ' . . . ,~
-4- ~-~: ' ` ` ":
Another aspect of the invention relates to a discharge lamp having an inert gas as the primary filling gas at a cold-fill gas pressure in the range 300 to 500 torr together with a metal halide to modify the discharge such that the lamp may be operated at current densities sufficiently in excess of 16 mA/sq.mm for a region of positive differential resistivity to occur.
Figure 1 of of the drawings shows voltage~current chæ acteristic curves for two lamps each having an arc length of 75 mm and a bore of 4 mm. One lamp included an ' ~' '' .' :'':' ," ':.
, :. .
. . . : .
1(~3~
excess of indium iodide and the other an excess of sodium iodide. At currents of a little above 1 a~p (equivalent to 80 mA/sq.mm) a positive resistance characteristic is found.
~hese lamps were found to operate satisfactorily if the xenon pressure was reduced to 200 torr. 1 Mg of metal iodide or of each of the metal and iodine was sufficient for -~
these lamps. ~ ;~
- ~igure 2 of the drawings-illustrates a discharge lamp ~ -with which the invention can be employed~ It comprises a quartz envelope 10 and two electrodes 12, which can comprise .
either a pure tungsten shank or a thoriated tungsten metal.
The halides of any of the following elements can be 1: ., used to increase the slope of the resistance characteristic in an inert gas discharge lamp~ namely, sodium, lithium, ! : :
cadmium? zinc, magnesium, indium, thallium, gallium, tin, and lead. It is possible to replace the xenon in the lamp5 described wholly or partially by krypton.
. . .
` ' '`,:
:,, ~''''~"
; -, ;':
: , , ~' ', '. ' ':
..
' " ' . ' .
_5_ : . :
~ "
::
.... ...... . .
- ,.-. .
; , ' "' '~~':
:. "'.,"'.'',~,
In an article in l'Applied Optics" Vo1~ 10, ~o. 11, ~ovember 19711 pp. 2517 - 2520, C.~. Gallo has described the production of "Continuous emission spectra from long linear ~
xenon discharge lamps with metallic halide additives". ~ ~-Gallo used thallium iodide or tin iodide as the additi~e, which was present in excess as a solid mass filling the volume behind the electrodes. ~he cold-filled xenon pressure was between 25 torr and ~ 2 atm. ~nd the optimum value was found to be around 80 torr. l'he lamps had a negative dif~erential resistivit~, that is to say, the arc ~oltage dropped as the current increased, and in conseque~ce the current used by Gallo was limited to values below 140 mA at ~bout 4.5 K~. ~he lamps described by Gallo had quartz envelopes with an internal diameter of 3.5 mm, thus the current density was below 14.5 mA/sq.mm. The lamps operated in a power ran~e between a few watts per linear cm and`about 30 watts per linear cm.
- The Applicant has now found that b~ operating dis- ;
charge lamps of the kind described by Gallo at higher current densities in excess of 16 mA/sq.mm, and generally in the range of 20 mA/sq.mm to 140 mA/sq.mm or more, one obtains a .
positive differential resistivity with the arc voltage i~creasin~ with current, which allows the stabilising ballast ~-: . ~ ::
, .. . .. ..
.
~03710~7 normally used to be much reduced in size or even elimin-ated altogether s~nce the lamp becomes self-stabilising.
For optimum operation in this re~ion it is found that cold-fill xenon pressures o~ 300 to 500 torr and preferably 400 to 500 torr are desirable, in contrast to the preferred pressure of about 80 torr in Gallo's lamps. It is then possible to obtain luminous efficiencies in excess of 50 lumens/watt and under favourable conditions of 8G lumens/watt and even as high as 125 lumens/watt.
As alternatives to thallium iodide the Applicant has also used sodium iodide and gallium iodide, in each case in excess. With arc tubes of about 8 mm diameter, that is to say, somewhat lar~er than those of Gallo, and~a xènon cold-fill pressure of around L~50 torr in each case, the transition 'l5 from a negative to a positive differential reslstivity took place at about 1.3A for ~allium, 2.5A for thallium, and 4~5A
for sodium, corresponding to current densities of about 25, 50 and 90 mA/sq.mm respectively. ~he positive slope i~
steepest for ~allium and least steep for sodium. In all cases the lumi~ous efficiency rises as the current is increased on the positive side of the curve. The arc voltage for gallium iB in excess of 340 volts, and that for thallium above 145 volts, while for sodium it is above 108 volts.
In the case of lamps containing an excess of ~odium iodide, with a guart3 tube of bore diameter from 6 to 10 m~ ;
it has been found that the optimum xenon pressure lies in . .
~3~
.
'.
~ al37(3g~
the range 400 to 500 torr and is preferably about 450 torr.
With a power input of 40 W~linear cm a luminous efficiency of 125 lumens~watt has been achieved, while at a lower loading - of 25 W/linear cm the efficiency is 80 lumens/watt. The colour of the light is that of low pressure sodium, with a chromaticity of x = 0.562, y = 0.410. To provide arc ignition in the xenon fill gas it is necessary to use an ignition voltage of some 20 Kv. It is possible to operate such a lamp on the positive part of its resistivity characteristic with a lamp ballast which carries a differential of only l volt between the lamp voltage and the supply voltage.
In one specific example, the arc tubè is formed of . .
fused silica, had a bore of 8 mm diameter, and provided an ` ~ `
arc length of l9 cm. 40 Mg of sodium iodide is contained in the tube, which is filled with xenon at 450 torr. Above a current from a minimum of around 108 volts and using minimal ~` -..
impedance in series with the lamp, an 8~ rise in voltage will result in a 22% rise in wattage. To keep lamp watts within : . :.
acceptable limits it may be desirable to use a small ballast choke but this need be no more than a quarter of the weight and size o the normal choke used with a mercury-filled discharge lamp.
According to one broad àspect, the invention relates to a method of operating a discharge lamp which comprises providing a lamp having an inert gas as the primary filling gas at a cold- -fill pressure in the range 300 to 500 torr together with a metal halide to modify the discharge, and passing a current through ~
the lamp at a currenk density sufficientiy greater than 16 mA~ ``
sg.mm for the lamp to operate in a region of positive differential resistivity.
' . ' . . . ,~
-4- ~-~: ' ` ` ":
Another aspect of the invention relates to a discharge lamp having an inert gas as the primary filling gas at a cold-fill gas pressure in the range 300 to 500 torr together with a metal halide to modify the discharge such that the lamp may be operated at current densities sufficiently in excess of 16 mA/sq.mm for a region of positive differential resistivity to occur.
Figure 1 of of the drawings shows voltage~current chæ acteristic curves for two lamps each having an arc length of 75 mm and a bore of 4 mm. One lamp included an ' ~' '' .' :'':' ," ':.
, :. .
. . . : .
1(~3~
excess of indium iodide and the other an excess of sodium iodide. At currents of a little above 1 a~p (equivalent to 80 mA/sq.mm) a positive resistance characteristic is found.
~hese lamps were found to operate satisfactorily if the xenon pressure was reduced to 200 torr. 1 Mg of metal iodide or of each of the metal and iodine was sufficient for -~
these lamps. ~ ;~
- ~igure 2 of the drawings-illustrates a discharge lamp ~ -with which the invention can be employed~ It comprises a quartz envelope 10 and two electrodes 12, which can comprise .
either a pure tungsten shank or a thoriated tungsten metal.
The halides of any of the following elements can be 1: ., used to increase the slope of the resistance characteristic in an inert gas discharge lamp~ namely, sodium, lithium, ! : :
cadmium? zinc, magnesium, indium, thallium, gallium, tin, and lead. It is possible to replace the xenon in the lamp5 described wholly or partially by krypton.
. . .
` ' '`,:
:,, ~''''~"
; -, ;':
: , , ~' ', '. ' ':
..
' " ' . ' .
_5_ : . :
~ "
::
.... ...... . .
- ,.-. .
; , ' "' '~~':
:. "'.,"'.'',~,
Claims (7)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS;
1. A method of operating a discharge lamp which comprises providing a lamp having an inert gas as the primary filling gas at a cold-fill pressure in the range 300 to 500 torr together with a metal halide to modify the discharge, and passing a current through the lamp at a current density sufficiently greater than 16 mA/sq. mm for the lamp to operate in a region of positive differential resistivity.
2. A method according to claim 1 wherein the current density is greater than 20 mA/sq.mm.
3. A method according to claim 1 or 2, wherein the current density is less than 140 mA/sq.mm.
4. A discharge lamp having an inert gas as the primary filling gas at a cold-fill gas pressure in the range 300 to 500 torr together with a metal halide to modify the discharge such that the lamp may be operated at current densities sufficiently in excess of 16 mA/sq.mm for a region of positive differential resistivity to occur.
5. A discharge lamp according to claim 4, wherein the metal halide is sodium iodide.
6. A discharge lamp according to claim 4, wherein the metal halide is gallium, thallium or indium iodide.
7. A discharge lamp according to claim 4, wherein the metal halide is a halide of one of any of the following metals, viz:
sodium, lithium, cadmium, zinc, magnesium, indium, thallium, gallium, tin and lead.
sodium, lithium, cadmium, zinc, magnesium, indium, thallium, gallium, tin and lead.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB25471/74A GB1502612A (en) | 1974-06-07 | 1974-06-07 | Discharge lamps containing an inert gas and a metal halid |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1037097A true CA1037097A (en) | 1978-08-22 |
Family
ID=10228252
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA228,708A Expired CA1037097A (en) | 1974-06-07 | 1975-06-06 | Discharge lamps containing an inert gas and a metal halide |
Country Status (9)
| Country | Link |
|---|---|
| JP (1) | JPS5110682A (en) |
| AU (1) | AU501780B2 (en) |
| CA (1) | CA1037097A (en) |
| DE (1) | DE2525408C3 (en) |
| FR (1) | FR2274139A1 (en) |
| GB (1) | GB1502612A (en) |
| IT (1) | IT1038753B (en) |
| NL (1) | NL7506708A (en) |
| ZA (1) | ZA753665B (en) |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6653801B1 (en) | 1979-11-06 | 2003-11-25 | Matsushita Electric Industrial Co., Ltd. | Mercury-free metal-halide lamp |
| JPS5691368A (en) * | 1979-12-24 | 1981-07-24 | Toshiba Corp | Metal halide lamp |
| US4783615A (en) * | 1985-06-26 | 1988-11-08 | General Electric Company | Electrodeless high pressure sodium iodide arc lamp |
| EP1002450B1 (en) * | 1997-08-05 | 2002-10-16 | Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH | Method for operating a direct current metal halogen arc lamp and circuit pertaining thereto |
| EP1032010A4 (en) * | 1998-09-16 | 2001-11-28 | Matsushita Electric Ind Co Ltd | Anhydrous silver halide lamp |
| US7847484B2 (en) * | 2004-12-20 | 2010-12-07 | General Electric Company | Mercury-free and sodium-free compositions and radiation source incorporating same |
| US7825598B2 (en) | 2004-12-20 | 2010-11-02 | General Electric Company | Mercury-free discharge compositions and lamps incorporating Titanium, Zirconium, and Hafnium |
| US7928669B2 (en) | 2008-02-08 | 2011-04-19 | General Electric Company | Color control of a discharge lamp during dimming |
-
1974
- 1974-06-07 GB GB25471/74A patent/GB1502612A/en not_active Expired
-
1975
- 1975-06-04 AU AU81853/75A patent/AU501780B2/en not_active Expired
- 1975-06-05 NL NL7506708A patent/NL7506708A/en not_active Application Discontinuation
- 1975-06-06 CA CA228,708A patent/CA1037097A/en not_active Expired
- 1975-06-06 JP JP50067687A patent/JPS5110682A/ja active Pending
- 1975-06-06 DE DE2525408A patent/DE2525408C3/en not_active Expired
- 1975-06-06 ZA ZA00753665A patent/ZA753665B/en unknown
- 1975-06-06 IT IT24098/75A patent/IT1038753B/en active
- 1975-06-09 FR FR7517960A patent/FR2274139A1/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| DE2525408A1 (en) | 1975-12-18 |
| FR2274139B1 (en) | 1979-06-22 |
| NL7506708A (en) | 1975-12-09 |
| GB1502612A (en) | 1978-03-01 |
| DE2525408C3 (en) | 1980-02-28 |
| ZA753665B (en) | 1976-05-26 |
| AU8185375A (en) | 1976-12-09 |
| IT1038753B (en) | 1979-11-30 |
| JPS5110682A (en) | 1976-01-28 |
| DE2525408B2 (en) | 1979-06-21 |
| FR2274139A1 (en) | 1976-01-02 |
| AU501780B2 (en) | 1979-06-28 |
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