EP0110249B1 - Hochdrucknatriumlampe mit verbesserter Farbenwiedergabe - Google Patents

Hochdrucknatriumlampe mit verbesserter Farbenwiedergabe Download PDF

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Publication number
EP0110249B1
EP0110249B1 EP83111493A EP83111493A EP0110249B1 EP 0110249 B1 EP0110249 B1 EP 0110249B1 EP 83111493 A EP83111493 A EP 83111493A EP 83111493 A EP83111493 A EP 83111493A EP 0110249 B1 EP0110249 B1 EP 0110249B1
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EP
European Patent Office
Prior art keywords
sodium
high pressure
arc tube
lamp
hps
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
Application number
EP83111493A
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English (en)
French (fr)
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EP0110249A2 (de
EP0110249A3 (en
Inventor
Jack Mack Strok
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
General Electric Co
Original Assignee
General Electric Co
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Filing date
Publication date
Application filed by General Electric Co filed Critical General Electric Co
Publication of EP0110249A2 publication Critical patent/EP0110249A2/de
Publication of EP0110249A3 publication Critical patent/EP0110249A3/en
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Publication of EP0110249B1 publication Critical patent/EP0110249B1/de
Expired legal-status Critical Current

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    • 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
    • H01J61/825—High-pressure sodium lamps
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00—Gas-discharge or vapour-discharge lamps
    • H01J61/02—Details
    • H01J61/30—Vessels; Containers
    • H01J61/302—Vessels; Containers characterised by the material of the vessel

Definitions

  • This invention relates to a high pressure sodium vapor lamp utilizing alumina ceramic inner envelope and is particularly concerned with a high pressure sodium lamp having an inner arc tube of alumina ceramic operated at a relatively high pressure and having a desired color rendition which is maintained during the life of the high pressure sodium lamp.
  • High pressure sodium vapor lamps have found widespread use during the past decade for commercial lighting applications, especially outdoor lightings. Such lamps are described in U.S. Patent No. 3,248,590-Schmidt, High Pressure Sodium Vapor Lamps.
  • High pressure sodium lamps typically utilize a slender tubular inner envelope of transmissive refractory oxide material resistant to sodium at high temperatures, suitably high density polycrystalline alumina.
  • the inner envelope typically contains a gas atmosphere comprised of sodium along with a rare gas such as xenon to facilitate starting, and mercury for improved efficiency.
  • a gas atmosphere comprised of sodium along with a rare gas such as xenon to facilitate starting, and mercury for improved efficiency.
  • the partial pressure of Sodium Vapor is in the range of 3.999 ⁇ 10 3 to 1.333 ⁇ 10° Pa (30 to 1000 Torr); the fill pressure of xenon is approximately 2.666 103 Pa (20 torr).
  • the ends of the inner envelope are sealed by suitable closure members affording connection to thermionic electrodes which may comprise a refractory metal structure activated by electron emissive material.
  • the ceramic arc tube is generally supported within an outer vitreous envelope or jacket provided at one end with the usual screw base.
  • the electrodes of the inner envelope are connected to terminals of the base, that is to shell and center contacts.
  • the space between the inner and outer envelope is typically evacuated in order to conserve heat.
  • the color rendition of standard high pressure sodium (HPS) lamps may be improved by increasing the internal sodium partial pressure within the arc chamber of the inner envelope formed of polycrystalline alumina.
  • An improved color rendition of a standard HPS lamp may desire that the polycrystalline alumina arc chamber be operated with two to three times the internal sodium partial pressure relative to a conventional standard HPS lamp.
  • the wall temperature between electrode tips within the arc chamber may be increased by 100°C relative to a standard HPS lamp in order to offset the reduction of luminous efficacy which normally accompanies operation at increased sodium pressures.
  • Higher internal sodium pressures as well as higher arc chamber wall temperature typically shortens the life of improved color HPS lamps relative to their standard color, high efficacy HPS lamp counterparts.
  • manufacturers of improved color high pressure sodium lamps typically classify their products at 8,000-10,000 life hours as compared to 20,000-30,000 life hours for standard color products.
  • the life reduction of improved color HPS lamps typically occurs by the major factors of sodium losses from the arc chamber due to reactions with the inner surface of the arc chamber and through migration of the sodium through the walls of the arc chamber.
  • Sodium losses result in HPS lamp voltage rise, decrease of correlated color temperature of the HPS lamp, decrease of color rendition index and a color shift from a desired warm white color to an undesired pink color.
  • the sodium which migrates through the arc chamber deposits on the inside wall of the evacuated outer chamber where reaction with the glass and evaporation products from the alumina arc chamber cause a brownish stain on the outer chamber, which, in turn, reduces the light output of the HPS lamp. The brownish stain further aggravates undesirable lamp voltage rise of the HPS lamp.
  • objects of the present invention are to provide means for reducing the loss of sodium from an improved color HPS lamp operated at relatively high pressures contributed by the sodium within the arc chamber of the HPS lamp, and to provide such a high pressure sodium lamp having a color rendition index which remains substantially constant over the life of the improved color HPS lamp.
  • This invention is directed to an improved color rendition high pressure sodium lamp operated at increased sodium pressures having means for reducing the sodium losses typically created by the increased sodium high pressure operation.
  • a high pressure metal vapor lamp having an outer vitreous envelope enclosing an inner arc tube having thermionic electrodes sealed in its ends and containing a charge of vaporable metals having a sodium partial pressure in the range of 1.333 104 to 3.999 104 Pa (100 to 300 torr) and Xenon having a pressure in the range of 1.333 103 to 3.999 103 Pa (10 to 30 torr) is disclosed.
  • the inner arc tube has a chamber comprised of an optically translucent polycrystalline alumina ceramic chamber formed of the composition containing MgO and having an additive selected from the group consisting of Zr0 2 and Hf0 2 and mixtures thereof.
  • the high pressure vapor lamp according to the present invention has a general color rendition index in the range of 50-85.
  • FIG. 1 is a front elevational view of a high pressure sodium vapor discharge lamp according to the present invention.
  • a high pressure sodium vapor lamp 10 embodying the invention and corresponding to a conventional 400 watt size is illustrated in Figure 1.
  • the high pressure sodium (HPS) vapor lamp 10 comprises a vitreous outer envelope 12 with a standard mogul screw base 13 attached to the stem end which is shown uppermost in Figure 1.
  • a re-entrant stem press 14 has a pair of relatively heavy lead-in conductors 15 and 16 extending through the stem 14 and having outer ends of conductors 15 and 16 connected to the screw shell 17 and eyelet 18 of the base.
  • the HPS lamp 10 has inner envelope or arc tube 19 centrally located within the outer envelope 12.
  • the arc tube 19 is comprised of a length of light transmitting ceramic formed of a polycrystalline alumina ceramic which is translucent.
  • the upper end of the arc tube 19 is closed by an alumina ceramic plug 20 through which extends hermetically a niobium inlead 21 which supports an upper electrode (not shown) within the arc tube 19.
  • the lower end of arc tube 19 has a closure which comprises a ceramic plug 22 through which extends a thin-walled niobium tube 23.
  • the niobium tube 23 serves both as an inlead for arc tube 19 and a reservoir for excess alkali metal and mercury of the arc tube 19.
  • the shank of the lower electrode (not shown) of arc tube 19 projects into tube 23 and is locked in place by crimping the tube 23 about the lower electrode at location 24 as shown in Figure 1.
  • the crimping leaves restricted channels which allow passage of the alkali metal and mercury in vapor form but prevents movement of a liquid amalgam whereby the lamp may be burned not only base-up, as shown in Figure 1, but also burned as base-down.
  • the ceramic seals are described in greater detail in U.S. Patent 4,065,691 McVey, Ceramic Lamp Having Electrode Support by Crimp Tubular Inleads.
  • the arc tube 19 is of primary interest to the present invention and is illustrated in Figure 1 as respirilv broken-away so as to partially show the arc chamber 40 and the walls 42 both of arc tube 19.
  • the walls 42 have a thickness in the range 0.5 to 1.5 mm.
  • the arc tube 19 comprises an optically translucent polycrystalline alumina ceramic formed of a composition containing magnesium oxide (MgO) and having an additive selected from the group consisting of zirconium oxide (Zr0 2 ) and hafnium oxide (Hf0 2 ) and mixtures thereof.
  • the inner tube 19 is formed of 633 ppm by weight of MgO and 400 ppm of the additive Zr0 2 or Hf0 2 or mixtures thereof.
  • the HPS vapor lamp 10 of Figure 1 having the arc tube 19 has a general color rendition index in the range of 50-85.
  • the arc tube 19 formed of alumina and containing MgO, along with the additives Zr0 2 and Hf0 2 is described in U.S. Patent 4,285,732-Aluminum Ceramic, assigned to the same assignee of the present invention and herein incorporated by reference.
  • U.S. Patent 4,285,732 describes a method for producing an optically translucent polycrystalline sintered body through which light or radiation in the visible wavelengths is able to pass through sufficiently to make such body useful for optical applications such as enclosures for arc tubes such as arc tube 19.
  • an arc tube such as my arc tube 19 having the compositions described in U.S. Patent 4,285,732 has an unexpected and surprising superior characteristic of reducing the undesirable sodium losses within the arc tube 19 described in the "Background" section, which, in turn, provides a HPS lamp operable at increased pressures so as to improve the color rendition and also the color rendition of the improved lamp is maintained over increased life.
  • the standard HPS lamp of Table 1 may be of the commercially available LU400 400 watt type available from the Lighting Business Group of the General Electric Company, whereas the color improved lamp 10 of Table 1 is of a 250 watt type.
  • a comparison between the standard HPS lamp and my color improved HPS lamp both of Table 1 reveals, (1) my improved color HPS lamp 10 has a Color Rendering Index of 65, whereas, the standard HPS lamp has a Color Rendering Index of 20, (2) my improved color HPS lamp 10 has a correlated color temperature (CCT) of 2250 K, whereas, the standard HPS lamp has a CCT of 2100 K, and (3) my improved color HPS lamp 10 has a sodium pressure of 1.599 104 Pa (120 Torr) which is twice that of the standard HPS lamp having a typical sodium pressure of 7.998 ⁇ 10 3 Pa (60 Torr).
  • the standard HPS lamp with which the comparative test data was obtained was a 400 Watt rating having a typical operating sodium partial pressure of 7.998 103 Pa (60 torr) and having a general color rendition of 20.
  • a total of 10 standard HPS lamps were subjected to comparative testing.
  • the improved color HPS lamp 10 was similar to the standard HPS 400 watt lamp except that the HPS lamp 10 had the arc tube 19, previously described, having a selective additive of Zr0 2 and operated at a pressure in the range of 1.599 104 to 2.132 104 Pa (120 to 160 torr).
  • a total of 10 improved HPS lamps were subjected to the comparative testing.
  • the groups of the standard and improved HPS lamps were subjected to operation at 800 watts for a 100 hour duration. During the testing at 800 watts, both groups were determined to have an increased, relative to the 400 watt operation, general color index of approximately 65 and both groups had a maximum ceramic temperature approximately midway between the associated electrode tips of approximately 1,350°C.
  • This sodium beta-alumina is detrimental to the operation of the arc tube in that it chemically binds sodium making it unavailable for participation in the discharge condition of the arc tube and also the sodium beta-aluminum serves as a conductor path of sodium through the arc tube thereby further aggravating sodium losses and promoting arc tube jacket staining where it deposits.
  • the arc tube 19 of the improved HPS lamps of the invention showed no "white spots”.
  • a Scanning Electron Microscope (SEM) analysis on the inner surface of the arc tube 19 showed some scattered "whiskers" of sodium beta-alumina but no heavy concentrations or evidence of penetration of sodium reaction through the wall of the arc tube 19.

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  • Vessels And Coating Films For Discharge Lamps (AREA)

Claims (4)

1. Hochdruck-Metalldampflampe mit einem äußeren Glaskolben, der ein inneres Entladungsrohr umgibt, in dessen Enden thermionische Elektroden abgedichtet eingelassen sind und das eine Ladung aus verdampfbaren Metallen entält, die einen Natrium-Partialdruck im Bereich von 1,333×104 bis 3,999x104Pa (100 bis 300 Torr) und Xenongas bei einem Druck im Bereich von 1,333×103 bis 3,999x103 Pa (10 bis 30 Torr) aufweist, wobei das innere Entladungsrohr umfaßt:
eine optisch durchschneinende, polykristalline Aluminiumoxidkeramik aus einer Zusammensetzung, die MgO enthält und einen Zusatz aufweist, der aus der Gruppe bestehend aus Zr02, Hf02 und deren Mischungen ausgewählt ist,
wobei das genannte innere Entladungsrohr in Zusammenarbeit mit den angegebenen Druckbereichen von Natrium und Xenongas wirksam ist bei der Verminderung der typischerweise erwarteten Betriebsverluste an Natrium bei gleichzeitiger Erhöhung der Betriebsdauer der Hochdruck-Metalldampflampe und Schaffung einer im wesentlichen konstanten verbesserten Farbwiedergabe.
2. Hockdruck-Metalldampflampe nach Anspruch 1 mit einem allgemeinen Farbwiedergabe-Index im Bereich von 50 bis 85.
3. Hochdruck-Metalldampflampe nach Anspruch 1, wobei das innere Entladungsrohr 633 Gewichts-ppm MgO enthält und die Zusätze an Zr02 oder Hf02 oder deren Mischungen 400 Gewichts-ppm betragen.
4. Hochdruck-Natriumlamp nach Anspruch 1, wobei das innere Entladungsrohr eine Wanddicke im Bereich von 0,5 bis 1,5 mm hat.
EP83111493A 1982-11-26 1983-11-17 Hochdrucknatriumlampe mit verbesserter Farbenwiedergabe Expired EP0110249B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US44477882A 1982-11-26 1982-11-26
US444778 1999-11-22

Publications (3)

Publication Number Publication Date
EP0110249A2 EP0110249A2 (de) 1984-06-13
EP0110249A3 EP0110249A3 (en) 1985-05-08
EP0110249B1 true EP0110249B1 (de) 1988-10-19

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP83111493A Expired EP0110249B1 (de) 1982-11-26 1983-11-17 Hochdrucknatriumlampe mit verbesserter Farbenwiedergabe

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EP (1) EP0110249B1 (de)
JP (1) JPS59112563A (de)
CA (1) CA1209193A (de)
DE (1) DE3378287D1 (de)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB8725912D0 (en) * 1987-11-05 1987-12-09 Emi Plc Thorn Discharge arc lamp

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3248590A (en) * 1963-03-01 1966-04-26 Gen Electric High pressure sodium vapor lamp

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4285732A (en) * 1980-03-11 1981-08-25 General Electric Company Alumina ceramic

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3248590A (en) * 1963-03-01 1966-04-26 Gen Electric High pressure sodium vapor lamp

Also Published As

Publication number Publication date
EP0110249A2 (de) 1984-06-13
CA1209193A (en) 1986-08-05
DE3378287D1 (en) 1988-11-24
EP0110249A3 (en) 1985-05-08
JPS59112563A (ja) 1984-06-29

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