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US3351798A - Scandium halide discharge lamp - Google Patents

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US3351798A
US3351798A US30237663A US3351798A US 3351798 A US3351798 A US 3351798A US 30237663 A US30237663 A US 30237663A US 3351798 A US3351798 A US 3351798A
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pressure
mercury
lamp
high
scandium
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Bauer Arnold
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Patent-Treuhand-Gesellschaft fuer Elektrische Gluehlampen mbH
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Patent-Treuhand-Gesellschaft fuer Elektrische Gluehlampen mbH
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    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01JELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00Gas- or vapour-discharge lamps
    • H01J61/02Details
    • H01J61/12Selection of substances for gas fillings; Specified operating pressure or temperature
    • H01J61/18Selection of substances for gas fillings; Specified operating pressure or temperature having a metallic vapour as the principal constituent
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01JELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00Gas- or vapour-discharge lamps
    • H01J61/02Details
    • H01J61/12Selection of substances for gas fillings; Specified operating pressure or temperature
    • H01J61/125Selection of substances for gas fillings; Specified operating pressure or temperature having an halogenide as principal component

Description

Nov. 7,- 1967 RELATIVE SPECTPHLJNTENS/TY ,Q

A. BAUER 3,351,798 SCANDIUM HALIDE DISCHARGE LAMP Filed Aug. 15, 1963 700 WHVELNGTH (M/LL/M/CEONS) lnvervtor:

His A t torneg AvnQL'd B uev United States Patent 3,351,798 SCANDIUM HALIDE DISCHARGE LAMP Arnold Bauer, Augsburg, Germany, assignor to Patent- Treuhand-Gesellschaft fur Elektrische Glulrlampeu mbH Filed Aug. 15, 1963, Ser. No. 302,376

Claims priority, application Germany, Aug. 22, 1962,

6 Claims. (Cl. 313-225) The present invention relates to high pressure discharge lamps having solid hot electrodes and containing a filling which includes a compound of a metal excited in the high pressure discharge.

Amongst high-pressure lamps, the one most generally used is the high pressure mercury vapor lamp. It comprises an envelope consisting generally of quartz glass which contains a starting gas and a small quantity of mercury which is completely vaporized in operation of the lamp. The arc maintained at a vapor pressure of 1 to 25 atmospheres emits, besides a relatively weak continuum, primarily a line spectrum consisting of a few very strong lines. As a result, the light output of these lamps differs very much from natural light and also from the light emitted by an incandescent solid body, and color rendition is quite unsatisfactory. In order to improve the color rendition, it is already well known to add to the mercury other metals, as zinc or cadmium, for the purpose of increasing the percentage of red light emitted from the discharge. Such additions, however, cause a substantial decrease in light output which offsets the advantage gained in respect of color rendition.

In mercury vapor lamps of former construction provided with liquid mercury electrodes, the addition of salts, e.g. of halides, by means of which the mercury arc should get a definite coloration, was also known.

It has recently been proposed to provide in high-pressure mercury vapor discharge lamps with solid electrodes, in addition to the mercury filling, halide compounds of other metals which are excited to emission simultaneously with the mercury. Mercury vapor discharge lamps manufactured according to this proposal contain in most cases an addition of sodium iodide, potassium iodide, lithium iodide or thallium iodide. They show a satisfactory filling up of the deficiency in red of the mercury are without the decrease in light output occurring in prior mercury vapor lamps upon addition of zinc or cadmium. Since however none of the excited metals emits many more lines than mercury, the visible spectrum consists notwithstanding of a few lines only and is not equivalent to daylight in respect of color quality.

There may be obtained an excellent color rendition with a high-pressure discharge lamp in which rare earths are excited because their spectra have a close sequence of lines. However rare earths have the disadvantage of a very low vapor pressure, so that in order to obtain high light output the discharge envelope must have temperatures of more 1000 C. Thus by way of example, lanthanum iodide has a boiling point of 1400 C.

Within the scope of experiments with rare earth additions, it has been surprising to find that scandium compounds hold an exceptional position as against all other metals or metal compounds hitherto used for the filling.

If scandium is excited to radiant emission with definite intensity then it emits in the visible range just as close a light spectrum as the rare earths but Without any large energy losses in the ultraviolet and infrared ranges. Besides, the vapor pressure of some scandium compounds, especially that of scandium iodide ScI sufiices for a high pressure are. Thus, high-pressure lamps containing Sccompounds have two decisive characteristic features which have hitherto, not been found simultaneously in any highpressure lamp:

(1) The addition renders a light color which is extremely similar to natural daylight, in the same fashion as the light of a high-pressure xenon discharge lamp. This may be seen from FIG. 1 which shows the spectral energy distribution of a high-pressure lamp with an addition of S013.

(2) While additions of metal halides proposed hitherto have no bad influence on light output but do not greatly increase it, now however the efiiciency is raised to 105 lumens per watt (lm./w.) by addition of a Sc-compound.

For lamps with high output concentration and resulting high wall temperature, the envelope of which consists of quartz glass or fine-crystalline, transparent aluminum oxide and in which the scandium halide vapor pressure exceeds 1 atm., a filling of $01,, by way of example, is sufiicient. For the purpose of better starting, an additional rare gas filling at 10 to mm. of mercury cold pressure is desirable.

In case of wall temperatures below 900 C. as are usual for instance in ordinary high-pressure mercury lamps, the vapor pressure of ScI is below 1 atm. Thus for instance at 800 C., it amounts to 0.1 atm. Therefore, it is desirable to fill-in additionally with a heavier buffer gas at higher pressure in order to reduce losses due to heat conduction and diffusion. The exciting voltages of Se are low, generally below 4 volts. Therefore, a suitable buffer gas is a heavy gas having exciting voltages lying above this limit. The heavier rare gases for instance meet this requirement. Generally, an addition of mercury vaporizing completely in operation will be most suitable which ensures a partial pressure of more than 1 atm., e.g. of 5 to 25 atm. The average exciting voltage of mercury lies at about 7.8 volts and that of scandium below 4 volts, and an equal number of atoms of both elements are excited with a partial pressure ratio p /p -10 Provided the above-1nentioned ratio p /p =25/0.1 =250 or less, scandium radiation predominates.

In an electric high-pressure vapor discharge lamp with solid hot electrodes comprising an envelope consisting of refractory or high-melting, light transmissive material and containing a filling including a metallic compound, according to the present invention scandium is chosen as the added compound to be excited. The scandium compound may consist of Sel ScBr ScCl or of yet other scandium compounds with sufficient vapor pressure such as Sc S In a lamp with tungsten electrodes, the preferred compound is ScI because the iodine cycle then prevents vaporized tungsten from depositing on the bulb wall. The loading of the electrodes is desirably high enough that the tips or environments of the arc appendage thereon are molten in operation of the lamp.

The present invention provides a high-pressure lamp with excellent light output exceeding even that of a highpressure mercury arc, and which has a very good color rendition comparable with that of a highpressure xenon arc. Because of the relatively high vapor pressure of scandium halides, the lamp may be rated for an operating temperature as high as is usual for the well-known high-pressure mercury lamps. These lamps may, therefore, in advantageous manner he produced according to well developed methods of manufacture.

Beside scandium halide and, if desired, a quantity of mercury which is completely vaporized in operation, the lamp contains for the purpose of better starting a rare gas filling at some 100 mm. of mercury cold pressure. A small excess of halogen over the stoichiometric ratio corresponding to the scandium halide is desirable and may be introduced into the lamp for instance in the form of mercury halide.

Owing to the fact that a discharge is scandium contracts more than a discharge in mercury, the manufacture of a wall-stabilized lamp not artificially cooled is quite difiicult. A lamp according to the invention of high wall loading which is cooled artificially can be made as a capillary lamp. The diameter of the discharge space amounts to a few millimeters at most; the length of the arc, up to some centimeters.

For cases in which artificial cooling is not desired, electrode-stabilized lamps have been made. Wall loading in these amounts of 20 to 60 w./cm. preferably 40 w./cm. The interelectrode distance or gap for projection lamps may amount to some millimeters. The lamp bulb is spherical or oval like that of well known extra high-pressure mercury lamps. If the operating mercury vapor pressure therein is higher and amounts for instance to 25 atmospheres, then with an electrode distance of 6 mm., an operating voltage of 90 to 100 volts results. In lamps not having such high efiiciency, the operating pressure of the mercury vapor need not be so high. Thus an operating voltage of 150 to 25 volts is obtained with a vapor pressure of -10 atmospheres and an interelectrode distance of 1 to 2 cm.

FIG. 1 shows the spectral energy distribution of a high-pressure lamp with an addition of S01 FIG. 2 shows by way of example a lamp embodying the invention.

As illustrated in FIG. 2, the discharge envelope 1 consists of quartz glass and encloses a volume of 27 cm. The inner diameter of the tubular envelope which is closed spherically at both ends amounts to about 30 mm. The pin electrodes 2 and 3 consist of refractory metal, preferably of tungsten wire 1.2 mm. in diameter and have the usual foil inleads 4 and 5. The electrodes may be provided with tightly fitting quartz sleeves 6 and 7 passing integrally over into the quartz envelope 1 in order to suppress the iodine cycle at cooler places on the electrodes where tungsten sputtering may occur. Any electrode activation beyond the usual thorium addition should be avoided. The rare gas filling in order to facilitate starting amounts to mm. Hg of argon. The mercury filling vaporizing completely in operation and amounting to 304 milligrams results in a vapor pressure of about 10 atms. A filling of mg. ScI does not vaporize completely in operation. An addition of 3 mg. HgI brings about better behavior during life of the lamp.

The electrical and lighting data of the lamp are:

Wattage watts 2430 Current intensity amperes 13.3 Voltage volts 240 Electrode distance cm 1.5 Wall load w./cm. Luminous flux lumen 254,000 Efliciency lm./W. 105

An increase in output may easily be obtained with this lamp type by enlarging the lamp envelope and/or by means of forced cooling. Wall loading may be increased in simple manner up to 50% to 70% by putting the lamp into a glass tube 8 arranged vertically and open at both ends. The tube may be elongated upwardly for instance a length of 40 cm. and produces a cooling air fiow by chimney effect. With this arrangement, there may for instance be converted an electric energy of 10 kw. in a quartz burner having a length of 9 cm. and a diameter of 5.8 cm.

Beside the type with short are distance there was developed another type with greater arc distance which is operated with proportionately high voltage of for instance 400 to 600 volts. It has been found that such lamps require magnetic field stabilization.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A high pressure electric discharge lamp comprising an envelope of refractory light-transmitting material having a pair of slender solid tungsten electrodes sealed therein and containing a filling of mercury providing a vapor pressure in excess of 1 atmosphere when fully vaporized in normal operation, a quantity of scandium iodide in excess of that vaporizing during operation, and a rare gas at a cold filling pressure between 10 and millimeters of mercury.

2. A high pressure electric discharge lamp as defined in claim 1 wherein the partial pressure of mercury is in the range of 5 to 25 atmospheres and the ratio of partial pressure of mercury to partial pressure of scandium during operation does not exceed 250 in order to have scandium radiation predominating.

3. A lamp as defined in claim 1 wherein the filling contains additional iodine over the stoichiometric proportion corresponding to the scandium iodide present.

4. A high pressure electric discharge device comprising an arc tube having electrodes sealed at either end thereof and a vaporizable fill of iodine, mercury and atoms of scandium; said iodine and mercury respectively being present in an atomic ratio of about 0.14 and said mercury being present in sufiicient quantities to be completely vaporized at normal operating temperatures of said are tube and to form a restricted arc therein, the atoms of said scandium being present in sufficient quantities to produce white light.

5. A high pressure electric discharge lamp comprising an envelope of refractory light-transmitting material having a pair of tungsten electrodes sealed therein and containing a filling of mercury providing a vapor pressure in excess of one atmosphere when fully vaporized in normal operation, a quantity of a scandium compound in excess of that vaporizing during operation, and a rare gas at a cold filling pressure between 10 and 100 millimeters of mercury.

6. A high pressure electric discharge lamp comprising an envelope of refractory light-transmitting material having a pair of tungsten electrodes sealed therein and containing a filling of mercury providing a vapor pressure in excess of 1 atmosphere when fully vaporized in normal operation, a quantity of a scandium halide in excess of that vaporizing during operation, and a rare gas at a cold filling pressure between 10 and 100 millimeters of mercury.

References Cited UNITED STATES PATENTS 2,673,944 3/1954 Francis 3l3228 3,234,421 2/1966 Reiling 313229 X FOREIGN PATENTS 900,200 7/1962 Great Britain.

OTHER REFERENCES PublicationReference Book of Inorganic Chemistry, Latimer and Hildebrand, published by Macmillan Co., copyright Third Edition, 1051, page 453 relied upon.

S. D. SCHLOSSER, Primary Examiner.

GEORGE N. WESTBY, Examiner.

Claims (1)

1. A HIGH PRESSURE ELECTRIC DISCHARGE LAMP COMPRISING AN ENVELOPE OF REFRACTORY LIGHT-TRANSMITTING MATERIAL HAVING A PAIR OF SLENDER SOLID TUNGSTEN ELECTRODES SEALED THEREIN AND CONTAINING A FILLING OF MERCURY PROVIDING A VAPOR PRESSURE IN EXCESS OF 1 ATMOSPHERE WHEN FULLY VAPORIZED IN NORMAL OPERATION, A QUANTITY OF SCANDIUM
US3351798A 1962-08-22 1963-08-15 Scandium halide discharge lamp Expired - Lifetime US3351798A (en)

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DE1962P0030071 DE1177248B (en) 1962-08-22 1962-08-22 Electric high-pressure vapor discharge lamp with a color-correcting additional stuffing

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Cited By (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3407327A (en) * 1967-12-21 1968-10-22 Sylvania Electric Prod High pressure electric discharge device containing mercury, halogen, scandium and alkalimetal
US3445719A (en) * 1967-05-31 1969-05-20 Duro Test Corp Metal vapor lamp with metal additive for improved color rendition and internal self-ballasting filament used to heat arc tube
US3450925A (en) * 1967-03-17 1969-06-17 Gen Electric Mercury bismuth halide photochemical arc lamp light sources
US3619682A (en) * 1969-04-01 1971-11-09 Sylvania Electric Prod Arc discharge lamp including means for cooling envelope surrounding an arc tube
US3832587A (en) * 1971-11-26 1974-08-27 Gte Sylvania Inc Heavily loaded metal halide discharge lamp
US3867665A (en) * 1973-07-05 1975-02-18 Thorn Electrical Ind Ltd Mercury discharge lamp comprising magnesium halide
US3876895A (en) * 1969-07-07 1975-04-08 Gen Electric Selective spectral output metal halide lamp
US3882345A (en) * 1971-11-22 1975-05-06 Gen Electric Metal halide discharge lamp containing tin and sodium halides
US3911308A (en) * 1974-02-07 1975-10-07 Matsushita Electronics Corp High-pressure metal-vapor discharge lamp
US4023059A (en) * 1972-06-05 1977-05-10 Scott Anderson High pressure light emitting electric discharge device
US4053805A (en) * 1974-12-09 1977-10-11 Gte Sylvania Incorporated Arc discharge lamp comprising mercury, scandium and lithium iodide, scandium emission being suppressed
US4199701A (en) * 1978-08-10 1980-04-22 General Electric Company Fill gas for miniature high pressure metal vapor arc lamp
US4237401A (en) * 1977-11-02 1980-12-02 U.S. Philips Corporation Low-pressure mercury vapor discharge lamp
US4310774A (en) * 1980-03-03 1982-01-12 Gte Products Corporation Arc discharge lamp containing scandium and scandium halide
US4605881A (en) * 1984-11-29 1986-08-12 General Electric Company High pressure sodium iodide arc lamp with excess iodine
US4682071A (en) * 1982-05-28 1987-07-21 The General Electric Company, P.L.C. Lamps and ribbon seals
US4705987A (en) * 1985-10-03 1987-11-10 The United States Of America As Represented By The United States Department Of Energy Very high efficacy electrodeless high intensity discharge lamps
US4709184A (en) * 1984-08-20 1987-11-24 Gte Products Corporation Low wattage metal halide lamp
US4783615A (en) * 1985-06-26 1988-11-08 General Electric Company Electrodeless high pressure sodium iodide arc lamp
US6545413B1 (en) * 1997-10-13 2003-04-08 Matsushita Electric Industrial Co., Ltd. Metal halide lamp
WO2006048830A2 (en) * 2004-11-03 2006-05-11 Koninklijke Philips Electronics, N.V. Quartz metal halides lamp with improved lumen maintenance

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3331982A (en) * 1964-10-20 1967-07-18 Sylvania Electric Prod High pressure electric discharge device having a fill including vanadium
US3398312A (en) * 1965-11-24 1968-08-20 Westinghouse Electric Corp High pressure vapor discharge lamp having a fill including sodium iodide and a free metal
CA989460A (en) * 1971-09-30 1976-05-18 Michael E. Fein Addition of buffering agent to gaseous medium of gas discharge device
US4387319A (en) * 1981-03-30 1983-06-07 General Electric Company Metal halide lamp containing ScI3 with added cadmium or zinc

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2673944A (en) * 1948-12-23 1954-03-30 Gen Electric Electric discharge lamp
GB900200A (en) * 1960-03-11 1962-07-04 Union Carbide Corp Improvements in and relating to electric incandescent lamps
US3234421A (en) * 1961-01-23 1966-02-08 Gen Electric Metallic halide electric discharge lamps

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Publication number Priority date Publication date Assignee Title
DE134732C (en) *
DE288228C (en) *
GB325534A (en) * 1928-11-16 1930-02-17 Standard Telephones Cables Ltd Improved method for introducing alkaline earth or rare earth metal vapours into evacuated or partially evacuated vessels
GB402747A (en) * 1931-03-03 1933-12-04 Rudolf Zaddach Improvements in or relating to electric gas and vapor arc discharge lamps
DE967658C (en) * 1949-09-04 1957-12-05 Heraeus Gmbh W C Vapor discharge lamp

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2673944A (en) * 1948-12-23 1954-03-30 Gen Electric Electric discharge lamp
GB900200A (en) * 1960-03-11 1962-07-04 Union Carbide Corp Improvements in and relating to electric incandescent lamps
US3234421A (en) * 1961-01-23 1966-02-08 Gen Electric Metallic halide electric discharge lamps

Cited By (22)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3450925A (en) * 1967-03-17 1969-06-17 Gen Electric Mercury bismuth halide photochemical arc lamp light sources
US3445719A (en) * 1967-05-31 1969-05-20 Duro Test Corp Metal vapor lamp with metal additive for improved color rendition and internal self-ballasting filament used to heat arc tube
US3407327A (en) * 1967-12-21 1968-10-22 Sylvania Electric Prod High pressure electric discharge device containing mercury, halogen, scandium and alkalimetal
US3619682A (en) * 1969-04-01 1971-11-09 Sylvania Electric Prod Arc discharge lamp including means for cooling envelope surrounding an arc tube
US3876895A (en) * 1969-07-07 1975-04-08 Gen Electric Selective spectral output metal halide lamp
US3882345A (en) * 1971-11-22 1975-05-06 Gen Electric Metal halide discharge lamp containing tin and sodium halides
US3832587A (en) * 1971-11-26 1974-08-27 Gte Sylvania Inc Heavily loaded metal halide discharge lamp
US4023059A (en) * 1972-06-05 1977-05-10 Scott Anderson High pressure light emitting electric discharge device
US3867665A (en) * 1973-07-05 1975-02-18 Thorn Electrical Ind Ltd Mercury discharge lamp comprising magnesium halide
US3911308A (en) * 1974-02-07 1975-10-07 Matsushita Electronics Corp High-pressure metal-vapor discharge lamp
US4053805A (en) * 1974-12-09 1977-10-11 Gte Sylvania Incorporated Arc discharge lamp comprising mercury, scandium and lithium iodide, scandium emission being suppressed
US4237401A (en) * 1977-11-02 1980-12-02 U.S. Philips Corporation Low-pressure mercury vapor discharge lamp
US4199701A (en) * 1978-08-10 1980-04-22 General Electric Company Fill gas for miniature high pressure metal vapor arc lamp
US4310774A (en) * 1980-03-03 1982-01-12 Gte Products Corporation Arc discharge lamp containing scandium and scandium halide
US4682071A (en) * 1982-05-28 1987-07-21 The General Electric Company, P.L.C. Lamps and ribbon seals
US4709184A (en) * 1984-08-20 1987-11-24 Gte Products Corporation Low wattage metal halide lamp
US4605881A (en) * 1984-11-29 1986-08-12 General Electric Company High pressure sodium iodide arc lamp with excess iodine
US4783615A (en) * 1985-06-26 1988-11-08 General Electric Company Electrodeless high pressure sodium iodide arc lamp
US4705987A (en) * 1985-10-03 1987-11-10 The United States Of America As Represented By The United States Department Of Energy Very high efficacy electrodeless high intensity discharge lamps
US6545413B1 (en) * 1997-10-13 2003-04-08 Matsushita Electric Industrial Co., Ltd. Metal halide lamp
WO2006048830A2 (en) * 2004-11-03 2006-05-11 Koninklijke Philips Electronics, N.V. Quartz metal halides lamp with improved lumen maintenance
WO2006048830A3 (en) * 2004-11-03 2006-06-22 Koninkl Philips Electronics Nv Quartz metal halides lamp with improved lumen maintenance

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Publication number Publication date Type
NL296907A (en) 1965-05-25 application
GB1024848A (en) 1966-04-06 application
DE1177248B (en) 1964-09-03 application

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